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COMM-T-95-002 C2

BIOLOGICAL STUDY

NONINDIGENOVS AQUATIC IN A :

A CASESTUDY OF THE BIOI OGICALINVASIONS OF THE SAN H4%NCISCO BAY AND DELTA

Andrew N. Cohen Energyand ResourcesGroup University of at Berkeley Berke!eyCaliforrua 94720

JamesT. Carlton Maritime Studies Program Williams College Mystic Seaport Mystic Connecticut06355

A Report for the UNITED STATESFISH AND WILDLIFESERVICE, WASHINGTON D. C. and THE NATIONAL SEA GRANT COLLEGEPROGRAM CONNECTICUT SEA GRANT U NOAA Grant MLunberNA36RG0467!

December 1995 .'.' l997

NtLTIGHALSU GIANTOEPOSggf PEll USRARYBOIUNg um HARIVlalLNSGTtNY Cg+g IEL CN82 Executive Suxrurtary

1 THESAN FRANCISCO BAY AND DELTA REGION IS A HIGHLYINVADED ZCOSYFIK4L TheSan Francisco Estuary can now be recognized asthe most invaded aquaticecosystem inNoxth America. Now recognized inthe Estuary are 212 introducedspecies: 69 percent of theseare invextebrates, 15percent are andother vertebrates, 12 percent are vascxxlar plants and 4 percentare protists. ~ In theperiod since 1850, the Bay and Delta repon has been invadedby an average of one new species every $6 weeks. Since 1970, the ratehas been at least one aew species every 24 weeks: the first coBection recordsof over50 non-nativespecies ia the Estuarysince 1970 thus appear to reflecta significantnew pulse of invasions. ~ In additionto the212 recognised introductions, 123 species are coasidered ascryptogenic not clearly native or introdxxced!, andthe total number of cryptogenictaxa in theEstuary might weil be twice that. Thus simply reportingthe documented intxoductions andassuming that aH other species in a regionare na tix~s virtuallyall previous studies have done severely underestimatesthe impact of marineand aquatic invasions on a region's biota. Nonindigenousaquatic and plants have had a pi'ofoundimpact on theecology of thisxegion. No shallow water habitat aow remains uninvaded byexotic species and, in some regions, it is difficult to find any native species in abundance.In someregions of theBay, 100@ of the coinmonspecies are introduced,creating "introduced communities." In locations ranging from freshwatersites in the Delta,through Suisun and SanPablo Bays and the shallowerparts of the CentralBay to the SouthBay, intmduced species accountfor the majorityof thespecies diversity.

2. A VAST AMOUNT OF ENERGY NOW PASSESTHROUGH AND IS UlKEKD BY THE NONINDIGKhJOUS BIOTA OF THE ESTUARY. IN THE 1990S, INTRODUCED SPECIES DOMINATE ANY OF mEESTUARY'S FOOD WEBS. ~ The majorblooxn-creating, donunant species are cxyptogenic. Becauseofthe poor state of taxonomic and biogeographic know'ledge, it remainspossible that many of theEstuary's major primary producers that providethe phytoplankton-derived energyfor andfilter feeders,are in fact introduced. ~ Introduced speciesare abundant ind doniinantthroughout the benthic and fouliagcouimunities of SanFrancisco Bay. Theseindude 10 speciesof introducedbivalves, most of whichare abxxndant to extremelyabundant, Intmducedfilter-feeding worms and may occur by the thousandsper squaremeter. Oa subhttoralhard substxates, the Mediterraneanmussel Mytttlls gallopomsciNIis is abundant,while float fouliaycommunities suppoxt large populations ofintxoduced filter feeders, includingbryoxoaas, and seasquirts. The holisticmle of the entire nonindigenousfilter-feeding guild iadudingdams, mussels, bryozeans, barnacles,seasquirts, spionid worms, serpulid worms, sponges, hydroids, andsea anemones in alteringand controlling the trophic dynamics of the Bay-Deltasystem remains unknown. The potenbal role of just one species, theAtlantic ribbed mussel Arcuafstla dern issa, as a biogeochemical agentin theeconomy of Baysalt isstriking. ~ Introducedclams are capable offiltering the entire volume otthe South Bay andthe northern estuarine regions ! once a day:indeed, it now appearsthat the primary inechanism controHing phytopiankton duringsummer and fall in SouthSan Francisco Way is "' filter feedingby the introduced Japanese clams Vetrerupis and hfrtscsdistN and the Atlanticclam Gejurna. This remarkable process has a significantimpact on thestanding phytoplankton stockin the South Bay, and since this isnow utilized almost entirely by introduced filter feeders, passing the energythrough a non-native benthic fraction ofthe biota may have fundamentallyaltered the energy available for native biota ~ Droughtyear control ofJrhytopiankton byintroduced clams resultina in the failureof the summer bloom to appear ln thenorthern reach of the Estuary is a remarkablephenonienon. the introducedAtlantic soft-shell clamsQLfya! alone were estiinated tobe capable attimes of filtering atl of the hytoplanktonfromthe onthe order ofonce pei day. hytoplanktonblooms occurred only during higher flow years, when the populationsofMya and other introduced benthic filter feeders retreated downstreamtosaltier parts of theEstuary. Phytopianktonpopulations inthe northern reaches ofthe Estuary maynow' becontinuously andpermanently controlled byintroduced clams.Arriving byballast w'ater and first collected i»the Estuary in1986, by 198S the Asian clamPotamocorbula reached and has since sustained average densities exceeding2,000/m2, Since the appearance ofPofamocorbda, thesummer diatombloom has disappeared, presumably because ofincreased filter feedingby this new invasion. The Poftun ocorbtda population inthe northern reachesofthe Estuary can Filter the entire water column over the channels morethan once per day and over the shallows almost 13times per day, a rate offiltration which exceeds thephytoplankton's specificgrowth rate and approachesorexceeds thebacterioplankton's specificgrowth rate. ~ Further,the Asian clam Pottrrtt ocorbda feeds atmultiple levels inthe ,consuining bacterioplankton, phytoplankton, andzooplankton !,andsomay substantially reducecopepod populations bothby depletionofthe copepods' phytoplankton foodsource andby direct predation.Inturn, under such conditions, thecopepodwating native opossumshrimp Ncortrysis maysuf fer a near-completecollapsein the northernreacIL Itwas during onesuch pattern thatmysid-eating juvenile stripedbasssuffered theirlowest recorded abundance. Thisexample and thelinkages between introduced andnative species mayprovide a direct andremarkable example ofthe potential iinpact ofan introduced specieson the Estllalys foodwebs. ~ Aswith the guild offilter feeders, theoverall picture ofthe impact of introducedsurface-dwelling andshallow-burrowing inggrazers anand d eliosit 't f eedersinthe Estuary isincompletely known. The Atlantic mudsnail Executive Summary

17yanassaislikely playing a significant if notthe mast ixnportant role in alteringthe diversi', abundance, size distribution, and recruitment of xnany specieson the intertidalmudflats of SanFrancisco Say. ~ The arrivaland establishment in 1989-90of theAtlantic green CNrciens xnaenasin SanFrancisco Bay signab a newlevel of trophicchange and alteration.The pee» crabis a foodand habitat generalist, capable of eating an extraordinarilywide variety of anixnaisand plants, and capableof inhabitingmarshes, rocky substrates, and f ouhngcoxnmunities. European, SouthAfrican, and recent Californian studies indicate a broadand striking potentialfor this crab to signi6cantly alter the distribution, density, and abundanceof preyspecies, and thusto profoundlyalter community struchire in the Bay.

~ Nearly 30 speciesof introducedmarine, brackishand freshwaterfish are now ixnportantcarnivores throughout the Bayaxld Delta. Easternand centralAmerican fish ,mosquito6sh, , , bluegilis, inlandsilverside, layemouth and , and striped bass are amongthe xnost significant predators, competitors, and habitatdisturbexs thmughout the brackishand freshwater reachesof the Delta, with often concoxnitantimpacts on native fish communities.The intmduced cray6sh Procambarusand Facifastecxxsmay play an importantrole, w hendense, in regulatingtheir prey plant and animalpopulations. Nativewaterfowl in theEstuary consume some introduced aquatic plants suchas brassbuttons! and native shazebirds feed extensively on introduced benthic invertebrates.

3. INTRODUCED SPECIESMAY 8E CAUSING PROFOUND SHtUCTULQ, CHANGES TO SOME OF THE ESTUARY'S HA8rrATS. ~ The Atlanticsalt-xnarsh cordgrass Spartxna eltcnijlora, which has converted 100sof acresof mudflatsin WiliapaBay, Washington, into grassislands, has becamelocally abundant in SanFrancisco Bay, and is competingwith the nativecordgrass. Spartinn alteruijlota has bmad potential for alteration.Its lazger and more ripd stexns, greater stem density, and higher rootdensities may decrease habitat for nativew etlandanimals and infauna. Densestands of S.altrmijfora may cause changes in sedimentdynamics, decreasesin benthic algal production became of lower light leveb below the cordgrasscanopy, and loss of shorebirdfeeding habitat thmugh colonization of xnudflats TheAustralian-New Zealand boring isopod S'phseronxN qaroylnem creates characteristic"Splxacroma topography" on many Bay shores, with many linear metersof fringingmud banks riddled with its haM~ntixneterdianieter holes. Thisisopod may axguably play a major,if not thechief, mle in erosionof intertidalsoft rock terraces along the shore of SanPablo Bay, due to their boringactivity that weakens the mck and facilitates its removal by wave action.Sphmxanl has been burrowing inta Bay shores for over a century, andit thusmay be that in certainzegions the iandtwater margin has retreatedby a distanceof atleast several metezs due to thisisopod's boring activities. ExccutiocSummery

4. HiMLli NO INTRODUCIION IN THE ESTUARYHAS UNAMBIGUOUSLY CAUSED THE EXTINCTIONOF A NATIVESPECIES, IMIODUCrIONS HAVELED TO THE COMPLZIX HABTI'AT OR REGIONAL BllTIRPATION OF SPECKS, HAVE CONTRIBUTED TO THE GLOBAL EXACTION OF A CALIFORNIA FRESHWATER FIS+ AND ARENOW SHtONGLYCONIIBUTING TO THEFURTHER DEMISE OF ENDANGERED MARSH BIRDS AND MAM54QS ~ Introducedfreshwater and anadromous fish have been directly implicated in theregional reduction and ,and the global extinction, of four nativeCalifornia fish. The ,green sun&eh, , striped bass,and black bass, through predation aud through competition for food andbreeding sites, have all beenassociated with theregional elimirLation of thenative Sacramento from the Delta. The introducedinland silversidesmay be a significantpredator on the larvaeand eggsof the native .Expansion of the introducedsmaBmouth bass has been associatedwith the decline in the native hardhead.Predation by largemauth bass, smallmouthblack bassand stripedbass may havebeen a majorfactor in the global extinctionof the thicktaiichub in Calif orni.

~ The situationof the California clapperrail may serveas a modelto assess howan may be affected by biological invasions. The rail sufferspredatron by introducedNorway rats and red fax;it mayboth feed onand be killed by introducedmussels; and it mayfind refugein introduced cordgrass,although this same cordgrass may compete with native cordgrass, perhapspreferred by the rail. Other potenbal model study systems include rntroducedcrayfish and their displacementof nativecrayfish; introduced gobiesand their relationship to the tidewater gaby; and the combined role that introducedgreen sunfish, bluegill, largemouthbass, and American bullfrogmay have played in thedramatic decline of nativered-legged and yellow-legged frogL

5 . THOUGH THE ECONOMIC IMPACIS OF INIIIODUCED ORGANISMS IN THE SAN FRANCISCOESTUARY ARE SUBSTANDARD THEY ARE POORLY QUAÃTII'IED. Althoughsome of the fish intentionally introduced into the Estuary by overnmentagencies supported substantial commercial food , these isheriesall declinedafter a timeand are now closed The , Pacifastacur, from , whose exact means of introductionis unclear, supportsthe Estuary's only remaining commercial food based ou ao introducedspecieL ~ The stripedbass sport fishery has resulted in a substantialtransfer of funds fromangl ers to thosewho supply inglers' needs, variously estimated, betweenX962 and 1992, between $l millionand $4S million per year. However,striped bass populations and the striped bass sport fishery have declineddramatically in recentyears. ~ Governmentintroductions of organisms for sport , as and for biocoutrolhave frequently not produced the intended benefits, and have sometimeshad harmful "side effects," such as reducing the populations of economicallyimportant species. ~ Fewnonindigenous organisms that were introduced tothe Estuary by other thangovernment intent have produced economic benefits. The clams Mye Execeh'vs S unsmary

and Vcnerepis,accidentally introduced with Atlaaticoysters, have supported commercialharvesting in the Bay or elsewhereon the Pacificcoast, aad a smallamount of recreationalharvesting in the Bay thoughthese claxns may have,to someextent, replaced edible native clams!; the Asianclam Corbicxdw is commerciallyharvested for foodand bait ia CaHforaiaon a sxnallscale; the Asianyellowfin goby is coxnxnercialiy harvested for bait: muskrat are trapped for furs;and the SouthAfrican marsh plant brassbuttons provides food for watexfowLThexe do not appear to be anyother significant econouuc benefits thatderive f rom nongovernmental oraccidental introductions tothe Estuary. ~ A singleintroduced organism, the shipworm Tcredo xxNoalis, caused $615 million6n 1992dollarsl of structuraldamage to maxitimefacilities in 3 years in the earlypart of the20th centuxy. Theeconomic impacts of hull foulingaad othership fouling axe dearly very large,but arenot documentedor quantifiedfor theEstuary. Most of the foulingincurred in theEstuary is dueto noaiadigenousspecies. Indirect impactsdue to theuse of toxicaati-fouling coatings may also be substantiaL Waterwayfouling by introducedwater hyacinth has become a problexnin theDelta over the last fifteen years, with other introduced plants beginning toadd to the problem in recent years. Hyacinth fouli~ hashad sigaxficant economicimpacts, including interference with navigaboa. ~ Perhapsthe greatest economic ixnpacts may derive from the destabilixingof theEstuary's biota due to the introductioaaad establisbxnentof an average of onenew species every 24 weeks.This phenomenalrate of species additionshas contributed to the failureof waterusers and regulatory agenciestomanage the Estuary so as to sustain healthy populations of anadromousand nativefish, resulting in iacreasinglimitabons and threats of limitationson waterdiversioas, wastewater discharges, channel , maintenance, construction and other economic activities in and near theEstuary, with implicationsfor thewhole of California'seconomy.

RESEARCH NEEDS

Muchrexnains unknown in termsof the phenomena,patterns, and pxocesses of invasionsin theBay and Delta, and thus large gaps remain in theknowledge neededto establisheffective management plans. The followingare examples of importantreseaxch aeeds aad directions:

1. EXPER114IENTAI. ECOLOGY OE INVASIONS Onlya fewof thehundreds of invadersin theEstuary have been the subject of quantitativeexperimental studies elucidating theix roles ia the Estuary's ecosystexnand their impactson native biota. Suchstudies should receivethe highestpriority.

2, REGIONAI. SHII' STUDY Uxgeatlyrequired is a SanFrancisco Bay Shipping Study which both updatesthe 1991data base available and expands that database to aII Bay and Kxccvtivc Summary

Delta ports.A biological and ecologicalstudy of the natureof ballast watezbiota arrivinginthe Bay/Delta system isurgently required. Equally pressing isa studyof thefouling organxsms entezing the Estuary on ships' hulls and in ships'seachests, in orderto assess whether this mechanism isnow becoming ofincreasing importanceand in ordezto moreadequately define the unzque role of ballastwater, A RegionalShipping Study would provide critical data for management plans.

3. INTRAIKGIONAL HUIKLN-MEDIATED DISPERSAL VECIQRS Studiesare required on the mechanisms andthe temporal and spatial scales of the distribution of zntroducedspecies by human vectorsafter they have become established.Such studies will be of particularvalue in light of any future introductionsof nuisanceaquatic pests.

4. STUDY OF THE BAITWORM AND LOBSTER SHIPF NG INDUSlMES This study has identified a znajor,unzegulated vector for exoticspecies invasionsin the Bqr: the constant release of invertebrate-laden seaweeds from New' England in associatronwith bait worm and lobster!importation. In. addition a new trade in exoticbait has commenced,centered around the importationof living Vietnamese nereid worms,and both the worms and their substratedeserve deta Hed study.These studies are urgently needed to addressthe attendantprecautionary managementissues at hand.

5. MOLECULAR GENErIC STUDIES OF INVADERS The applicationof modernmolecujar genetic techniques has already revealedthe crypticpresence of previouslyunrecognized invaders in theBay: the Atlanticclam MNca¹I¹ petals, theMediterranean mussel My tilesgalloprooi¹ciglis, andthe Japanese A¹zeliN "a¹rzte." Molecular genetic studies of the Say's newgreen crab Carci¹¹s!population may be of criticalvalue in resolvingthe crab's geographicorigins and thus the mechanism that brought it to California.Molecular geneticstudies of wormsof thegenus Glyoera and Nereisin the Baymay clarify if New Englandpopulations have or arebecoming established in the regionas a result of ongoinginoculations vta the bait wormindustry. Molecular analysis of other invasionswill doubtlessreveal, as with Macomaand Mytil¹s, a number of heretof ore unrecognizedspecies.

6. INCREASED UTILGMTION OF EXOTIC SPECIES Fishery,bait, and other utilization studies should be conducted on developingor enlargingthe scope of fisheriesfor introducedbivalves such as Mya, Ve¹er¹pis,and Cotbic¹la!,edible aquatic plants, smaller edible fish suchas Aca¹thagobi¹s!,and Carci¹srsand &iochcir!.

V. POTKNIlAL ZEBRA MUSSEL INVASION Studiesare neededon thepotential distribution, abundance and impacts of sebraznussels Drowse¹¹ poly¹zorpha andjor D. b¹ge¹sis!in California,to support e8oztsto controltheir introductionand to designfacilities such as water intalces andfish screens!that will continueto functionadequately should the mussels become established. CONTENTS

1. Introduction.,

2. Methods.,

3. IntroducedSpecies in the Estuary .10

4. CryptosenicSpecies in the Estuary 149

S. Results By TaxonomicGroup 154 By Native Region. 155 By Time Period.. 157 By Transport Mechanism 160

6. Discussion 167 Ecological Impacts. . 167 Economic Impacts,. , 190 Future Invasions ,202

7. Conclusions 210 Major Findings, . .210 Research Needs. .215

References.. 218

Appendix 1A. Introduced Terrestrial Plants, Birds and Reported from the San Francisco Estuary Appendix 1B. Descriptions of Introduced Terrestrial Plants Reported froTn the San Francisco Estuary Appendix 1C. Descriptions of Introduced Terrestrial Mammals Reported from the San Francisco Estuary Appendix 2. Earlier Inoculations into the San Francisco Estuary and Nearby Waters Appendix 3. Descriptions of Introduced Plants and Invertebrates in Areas Adjacent to the San FranciscoEstuary Appendix 4. Introduced Organisms in the Northeastern Pacific Known only from the San Francisco Estuary or its Watershed Appendix 5. Introduced Marine, Estuarineand Aquatic Organismsin Four Regional Studies TABLES AND FIGURES

Table 1. Introduced organismsin the SanFrancisco Estuary

Table 2. Cryptogenicspecies in the SanFrancisco Estuary

Table 3; Treatment of introduced speciesas marine or continental, for analysis by native region

Table 4. Associations of introduced speciesin the San FranciscoEstuary

Table 5. Patterns of invasion along the salmity gradient in the San Francisco Estuary and the adjoining coast

Table 6. Positive economic impacts of marine, estuarine and aquatic organismsintroduced into the SanFrancisco Estuary

Table 7. Negative economicimpacts of introduced marine,estuarme and aquatic organisms

Table 8. Recent records of nonindigenous speciesin the San Francisco Estuary whose establishment is uncertain

Table 9. Introduced speciesin adjacentareas with the potential to invade the San FranciscoEstuary

Table 10. Examplesof ongoinginoculations of nonindigenousspecies into the San Francisco Estuary

Figure 1. The San FranciscoEstuary

Figure 2. Invasions by taxonomic group: lower-level aggregation

Figure3. Invasionsby taxonomicgroup: higher-levelaggregation

Figure 4. invasions by native region

Figure 5. Invasions into the San FranciscoEstuary by period

Figure 6. Invasions into the Northeastern Pacific by period

Figure 7. Invasions by type of transport mechanism

Figure 8. Someexamples of damagecaused by thewood-boring shipworm Teredo rravalis in the San Francisco Estuary ACKNOWLEDGMENTS

Scores of individuals, scientists,agency representatives and xnembersof the publicassisted us with the compilationof the speciesrecords in this report.We gratefullyacknowledge these workers for their contributionsin the appropriate portion of the text. Membersof the First October1993! and SecondQuly 1994!San FranciscoBay Expeditions john Chapman,Jean Chapman, Sarah Cohen, Terry Gosliner, Claudia Mills, Luis Solarzanoand John Rees!were of inestimable help in our field and subsequent systematicwork. John Chapman spent many hours working over recentcollections of SanFrancisco Bay peracaridcrustaceans to resolve the status of numerous axnphipods and isopods. Gretchen Lambert identified several sets of ascidiansfrom the Bay, and William Santa and Marianne DiMarco-Temkin aided with the identification of bryozoans. Gary Gillingham Kinnetic Laboratories, Inc., Santa Cruz!, Mike Kellogg City and County of San Francisco!, Heather Peterson California Department of Water Resources!and Jan Thompson U. S. GeologicalSurvey! provided extensivespecies list from benthic surveysunder their respectiveaegises. Jaxnes Orsi California Departmentof Fish and Gaxne!provided assistancein our researchon zooplanktonand Sloan University of CaMornia! on foraminifera. S. ECONOMIC IMPACTS OF WOOD BORKRS AND FOULING ORGAMSMS The econoinicimpacts of w ood-boringorganisms bhipworms and gribbles! andof foulingorganisms ou commercial vessels, on recreationalcraft, in portsand marinas,and in water conduits! are clearly very large in theSan Francisco Estuary, but remainlargely undocumented and entirelyunquantifiecL A moderneconomic studyof thisphenomenon, including the economic costs and ecologicalimpacts of controlmeasures now in placeor forecast,is criticallyneeded.

9. ECONOMIC, ECOLOGICAL AND GMKDGICAL IMPACTS OF BIOERODING NOMNDIGENOUS SPECKS Largelyqualitative data suggest that the economic, ecological, and geological impactsof theguild of burrowingorganisms that have been historically and newly introducedhave been or areforecast to potentially be extensive in the Estuary. Experimental,quantitative studies on theiinpacts of burrowingand bioeroding crustaceansand muskratsin the Estuaryare dearly now needed to assessthe extentof changesthat have occurred or arenow occurring, and to fornithe basisfor predicting future alterationsin the absenceof controlmeasures.

10. POST-lNVASION CONTROL MECHANISMS Whilepriinary attention must be paid to preventing future invasions, studies shouldbegin on examining the broad suIte of potentialpost-invasion control mechanisms,including biocontrol, physical containment, eradication, and related strategies.A RegionalControl Mechanisms Workshop for pastand anticipated invasions could set the foundation for future research directions. Pagt 1

CHAPTER 1. INTRODUCTION

Over the pastfour centuriesthousands of speciesof freshwater, brackish water and salt water animals and plants have been introduced to the United States dalton,19S8; Carlton, 1979a, 1989, 1992b; Moyle, 1986;Hickman, 1993; Carlton 8z Geller,1993!. In someregions, such as the HawaiianIslands, aboriginal introductions date back more than two millennia Mooney k Drake, 1986!. The taxonomic, habitat and trophic range of this vast nonindigenous biota is impressive ranging from exoticflatworms Rectocephalaexofica! in the lily of Washington,D. C., to Mexicancrabs Ptatychirograpsusspectabitis ! in Florida , to aquaticrodents such as the SouthAmerican nutria Myocustercoypu! in the southern United States. The human role in changing the face of , in terms of the abundance and diversity of the animals and plants of lakes,rivers, , marshes, and coastlines, has been demonstratively profound: ~ Sea lampreys Petromyzorjmarinus! invaded the Great Lakes, destroying extensive native fisheries; the Eurasian carp Cyprinus carpi'!, released in in 1831,is now a national pest; Nevada's Ash Meadows kil1ifish Empetrichthys merriami! became extinct at the hands of introduced Inosquitofish,mollies, crayfish, and bullfrogs; and scoresof exotic fish species now dominate aquatic habitats from Florida to New York and from the Atlantic drainage to California. ~ Asian clams Corbiculafluminea! spread acrossall of North America in only 40 years,moving from west to east from the Columbia to California and then quickly acrossthe southern United Statesto the Atlantic seaboard,a dramatic and startling invasion of this - and pipe-fouling clam McMahon, 1982!. Fifty years later, European zebra mussels Dreissena polymorpha and Dreissenabugensis! are similarly spreading across North America this time from east to west, from the Great Lakes to the Mississippi and into Oklahoma. Alien plants including the spectacularly successfulpurple loosestrife Lyfhrum saticaria!,Eurasian watermilfoil Myriophyllum spicatum!and water chestnut Trapa natans! are now the dominant, and at times the only, vegetation, for hundreds of square miles of aquatic and marsh habitats in North America. Despite these many invasions, there are with rare exception no synthesesof the spatial and temporal patterns, mechanismsor impacts of these norundigenous aquatic and estuarine organisms. For the great majority of invasions, records are scattered among thousands of scientific papers and buried in general monographs, student theses, government reports, consultant studies and anecdotal accounts. While a comprehensive review of freshwater and marine invasions would be extraordinarily useful, an initial approach to understanding the ecological and economic impacts of nonindigenous aniznals and plants in U. S. aquatic and marine environments may be attained through case studies: the assessmentof the role of invasions in defined geographic regions, focusing on historical and modern-day Page 2 Jn troduction dispersalpathways, onthe biological, ecological and economic consequences pf invasions,and on prospectsfor future invasions. Wepresent here such a regionalstudy, focusing on one of the largest freshwaterand estuarine of the United States: the and Deltaregion, a regionknown to have sustained numerous invasions for over a century.

Q! PRIOR STATE OF KNOWLEDGE At thetime of ourstudy there was no synthesis available of the diversity and impactsof the nonindigenous aquatic and estuarine species ofthe San Francisco Bay andDelta region, an area that extends from the inland port cities of theCentral Valleyto thecoastal waters of the Pacific Ocean at theGolden Gate. Thisregion includes examples ofmost of the common aquatic habitats found throughoutthe warm and cool temperate climates ofthe United States and, as such, representsanideal theater for assessing thediversity and range of effects ofaquatic invasions.Within the Bay-Delta Region are fresh, brackish, and salt water marshes, sandflatsand mudQats, rocky shores, benthic sublittoral habitats of a widesediment range,eelgrass beds, emergent aquatic macrophyte communities, planktonic, nektonic,and neustonic communities, extensive fouling assemblages, and communitiesof burrowing and boring organisms in claysand wood. Also representedisa vast range of habitat disturbance regimes. Over a 140-yearperiod of substantialhuman commercialand other activities since about 1850 a minimum ofmore than 200 plants, protists and animals from the aquatic and coastal habitats of easternNorth America, Europe, Asia, Australia, and South America have invaded these ecosystems. Priorlists or descriptionsof the introduced freshwater, anadromous and estuarinefish faunain theSan Francisco Bay-Delta region were provided by Moyle 976b!and McGinnis 984!; of freshwatermollusks by Hanna966! and Taylor 981!;of marinemollusks by Nicholset al.986!; and of introducedmarine and estuarineinvertebrates by Carlton 975, 1979a,b!, supplemented by Carlton et al. 990!.Silva 979! andJosselyn k West 985! noted some introductions of marine andbrackish seaweeds, but no comprehensiveassessment of possibly introduced seaweedshad been made. Atwater et al. 979! provideda listof introducedvascular plantsin SanFrancisco Bay salt marshes, butappear not to have distinguished betweenaquatic plants that are characteristically found within marshes and essentiallyterrestrial plants that are occasionally found at theedges of or within marshes.During our study the Bay-Delta Oversight Committee ofthe California DepartmentofWater Resources produced a briefing paper summarizing some of thepreviously published information on introduced fish, wiMlife and plants of the Bay-Deltaregion BDOC, 1994!, and Orsi 995! published a list of introduced estuarinecopepods and mysids. No information had beencompiled on possibleintroductions among freshwaterinvertebrates including species of freshwatersponges, jellyfish, flatworms,oligochaete and polychaete worms, snails, clams, crustaceans, and introduction Page3

bryozoans!,freshwater macroalgae, or fresh, brackish or saltwater phytoplankton. Protozoanintroductions had been similarly neglected. Basedon the informationavailable prior to our study,and on consideration of extantlists of aquaticor marineintroductions in otherregions Leppakoski, 1984; den Hartog, 1987;Mills et al., 1993,1995; Jansson, 1994!, we had estimatedthat the numberof aquaticand estuarine introductions in theBay-Delta system could exceed 150invertebrate species, 20 fish species, 10 algal species, and 100 vascular plant species.

8! CONTRIBUTlONS OF THE PRESENT STUDY

Thepresent work is thefirst regionalcase study in theUnited States of the diversityand ecological and economic impacts of nonindigenousspecies in aquatic andestuarine habitats. Previous studies Mills et al.,1993, for theGreat Lakes; MiOs et al.,1996, for theHudson River! have largely concentrated onspecies check-lists with a minimalreview of ecologicalor economiceffects of theexotic biota. We intendthe present study to bea coinprehensivesynthesis which may serve as a comparative model for other regional studies in U. S. waters. Thepresent study also sets forth detailed and clear criteria for determining whichspecies are present and established within the study zone. Prior regional surveysof aquaticintroductions have implied but rarelydefmed these criteria, a situationthat impedes ready quantitative comparisons between regions. We include Chapter 5! a supplementallistof vascularplant species based upon criteria whichwe judge to approximatethecriteria in priorregional surveys of aquatic introductionsin theUSA, in orderto facilitatesuch comparisons. Thepresent study is alsothe first regionalsurvey of introductionsto mclude a listing{although preliminary! of cryptogenicspecies species which are neither demonstrablynative or introduced Chapter 4!. As discussedby Carlton996a!, the developmentof such lists is a necessaryfirststep in correctingprior tendencies to profoundlyunderestimate the potential extent of biologicalmvasions and in providinga morecomplete basis for understandingthe sources, characteristics and frequencyof successof biologicalinvaders. Botholder {Elton, 1958! and newer e. g. Mooneyk Drake,1986; Drake et al., 1989!reviews of biologicalinvasions propose a numberof theoreticalmodels to explainthe success of and plant invasions in regionswhere they did not evolve.However, for mostsuch studies, comprehensive data sets on the diversity of invasions,temporal patterns of mvasion,and ecological impacts have not been availableby whichto testthe applicability or robustnessof invasion theory. The presentstudy provides an extensive review of anintroduced biota exceeding 200 taxain a definedgeographic region, and thus provides a raredata set with whichto test invasion models. Page4

CHAPTER 2. METHODS

Aj DEHNITIONS

1. STUDY ZONE Thestudy zone for thisreport is definedas the estuarine and aquatic habitats thatare within the normal range of tidalinfluence in SanFrancisco Bay, the Sacramento-SanJoaquin Delta and tributaries, and referred to herein as the San FranciscoEstuary or theEstuary Fig. 1!. The primary data set Chapter3 andTable 1! containsall demonstrablynonindigenous organisms that are characteristically found in estuarineor aquatichabitats including marshes, , etc.!, and for whichthere is significantevidence supporting their establishment within the study zone.

2. PlUMARYDATA SEF.' INTRODUCED SPECIES IN THESAN FRANCISCO ESTUARY Inclusionin theprimary data set thus requires evidence demonstrating that theorganism in questionis ! notnative to theEstuary, and ! currently established in the Estuary. Wedefine native organisms as those organisms present aboriginally, which for theBay-Delta region means prior to 1769when the first European explorers enteredthe area.The types of evidencethat we utilized to determinethe native versusintroduced status of aquaticand estuarine organisms, as discussed by Carlton 979a! and Chapman k Carlton 991, 1994!, include: ~ globalsystematic evidence involving taxonomic information from both morphologyand molecular genetics! and biogeographic evidence, including the globaldistribution of closelyrelated species; ~ theexistence of identifiablemechanisms of human-mediated transport; historical evidence of presenceor absence; ~ archaeologicalevidence of presenceor absence; ~ paleontologicalevidence of presenceor absence; ~ the extentto whichdistribution can be explainedby naturaldispersal mechanisms; ~ rapid or sudden changesin abundanceor distribution; ~ highly restrictedor anornalouslydisjunct distributions in comparisonto distributions of known native organisms!; occurrencein assemblageswith other known introducedspecies; and ~ for parasitesor commensals,occurrence on introducedorganisms. Wedefine established organisms as those orgarusans present and reproducing "in the wild" whosenumbers, distribution and persistence over time suggestthat, barringunforeseen catastrophic events or successfuleradication efforts, they will continueto be presentin the future."In the wild" impliesreproduction and persistenceof the population without direct human intervention or assistance such Methods Page 5

Figure1. The San FranciscoEstuary Methods Page6 asreproductive assistance via hatcheriesor periodicrenewal of thepopulation throughthe importationof spat!,but mayinclude dependence on human-alteredor createdhabitats, such as water bodies warmed by the cooling-watereffluent from powerplants, pilings, floating docks, and salt ponds or othermanipulated, semi- enclosedlagoons. The types of evidencethat we usedto assessestablishment include: population size; ~ persistenceof the populationover time; ~ distribution broad or restricted! of the population, and trends in distribution; ~ for speciesdependent on sexualreproduction, the presence of both malesand females,and the presenceof ovigerousfemales; and ~ the agestructure of the populationas an indicatorof successfulreproduction.

3. OTHER DATA SKIS Beyondthe primary data set, we consideredand compiled information on severaladditional categoriesof organisms,including: ~ cryptogenicorganisms, that is, organismsin theEstuary that are neither demonstrablynative nor introduced Table2!; ~ nonindigenousorganisms that havebeen reported from or were intentionallyintroduced to the Estuary,but whichdid not becomeestablished or for which there is inadequateevidence regarding their establishment Table 8 and Appendix 2!; ~ nonindigenousorganisms which are establishedin aquaticenvironments tributary to or adjacentto the Estuary,and which may in the future extend their rangeinto the Estuary Table9!; ~ nonindigenousorganisms which are not characteristicallyfound in estuarine or aquatichabitats but which havebeen occasionally reported from or may make occasionaluse of the Estuary Appendix 1!. Probablythe largestand most difficult "grayzone" between the primary data set and organismsin theseadditional categoriesinvolves those nonindigenous plantsreported from coastalor freshwaterwetlands for whichspecific information on occurrencewithin the tidal boundaries of the Estuary is not available. Although previousregional studies of aquaticinvasions Mills et al., 1993,1995! have included many suchgray-zone plants, we limited inclusionin our primary data set to those that both: a! have habitat descriptions indicating that they are primarily marsh plants,and not primarilyterrestrial or moistground plants occasionally found in or nearmarshes; and b! havebeen reported specifically from the Delta,and not just from the CentralValley or the Bay Area generally.Similar questions arose, though less commonly, with other types of organisms,to which we applied similar logic. Those candidate organismswhich are not listed in Table 1 becauseof criterion a!, are instead listed in Appendix l. Adding the plants in Appendix 1 to the organismsin Table1 would producea list of nonindigenousorganisms for the Estuary comparablethose produced for the Great Lakes Mills et al., 1993!and the Hudson River Mills et al., 1995!,as discussedfurther in Chapter 5, Candidate organismswhich failed to meetcriterion b! arelisted in Table9. Even following these restrictive criteria, we may have included in Table 1 some plants that are foundin theDelta region m rnarshesor dikedponds, but not in tidalwaters.

8! DATA SOURCES AND PRESENTATION

Initial lists of taxa in the above-describedcategories were compiledfrom the prior studiesdiscussed in theintroduction and from a reviewof theregional biologicaland systematic literature including regional monographic studies, keys, fieldguides and checklists; from published mainly in thegray literature! and unpublishedspecies lists generated by public agencies and private consultants; and from discussionswith taxonomists,field biologists,refuge managers and consultants familiar with the region. Furtherinformation on the speciesthus identifiedwas developedthrough a reviewof the pertinentcurrent and historical biological literature, museum records andspecimen collections, and interviews with biologists. We also undertook limited field work in order to checkthe presenceor distribution of certain species, andto checkfor thepresence of previouslyunreported species in somerarely sampledhabitats. This information was used to developthe following species hsts: Table1, listingintroduced species in the Estuary; ~ Table2, listing cryptogenicspecies in the Estuary; ~ Table8, listing species recently recorded from the Estuary but whose establishment is uncertain; ~ Table9 andAppendix 3, listing introduced species in adjacentaquatic habitats; Appendix1, listing terrestrial species that may occasionally befound in the Estuary; ~ Appendix2, listing older inoculations of nonindigenous species that did not become established; and Appendix4, listing introduced species in thenortheastern Pacific known only from the Estuary. Foreach species listed in Table1 wedetermined where possible: the date of first collectionor observationor planting in the Estuary, in California and in northeastern Pacific waters or coastal states or pro>aces; and where this was unavailable,the date of the first written accountof the organismin the area; the native range of the species; the immediategeographic source of' the introduction; ~ the transport mechanism; ~ theorganism's current taxonomic status, most frequently utilized synonyms, and common names; and its currentspatial distribution and abundance in the Estuary- We includedcommon names from Turgeonet al. 988! andCarlton 992! far mollusks,Cairns et al. 991! for coelenterates,Williams et al.989! for Methods

decapods,Gosner 978! for otherinvertebrates, Robins etal. 991! for fish and Hickman983! for higher plants. Thedata are presented inthe species descriptions inChapter 3 and summarized inlarge part! in Table 1.Some ofthese data are also provided forthe specieslisted m Tables8 and 9 andthe appendices. Wealso reviewed theavailable iMpanationonthe ecological roles and economic impacts ofindividual introduced speciesand of introducedspecies assemblages. Thisinformation issummarized in thespecies descriptions ~ Chapter 3and discussed inChapter 6.

C! ANALYSIS Theprimary data set in Chapter 3 and Table 1 wasquantitatively analyzed withregard to taxonoinic groups, native regions, timing and transport mechanisms. Theresults are presented in Chapter5.

TAXONOMY Thenumbers of speciesper taxonomic group were tabulated attwo levels of aggregation.A first tabulatian was done at the taxonomic levels of order for vertebrates!,phylum for invertebrates!,subkingdom forplants! and kingdom for protozoans!.A semnd, more highly-aggregated,tabulation was done at thelevels of class vertebrates!, atraditional, non-phyletic grouping invertebrates!, andkingdom plants and protozoans!.

2. NATIvE REGION Thenumbers of species per native region were tabulated with regard to elevenmarine regions and five continentalregions. The marine regions consist of theeastern and western portions of theNorth and South Atlantic oceans and the Northand South Pacific oceans, the Indian Ocean, the Mediterranean Sea, and the Blackand Caspian Seas. The Western South Pacific region consists primarily of watersaround Australia and NewZealand. The five continental regions consist of North America,South America, Eurasia, Africa, and Australia/New Zealand. Wherean organism's native range included more than one region, that orgazusm's count was split proportiona-lly-

3. QMING Weanalyzed the timing of introductionsin termsaf boththe date of first recordin the~tuary an+ &e datepf firstrecord in thenortheastern Pacific. Tlute numbersofspecies were tabulated infour 30-year periods with the first beginning in 18%and the last ending in 1969and one 26-year period 970-1995!. Inthe few cases wherean organism's date of firstrecord was a periodthat spanned parts of two tabulationperiods, that org+zdsm'scount was proportionally divided between the periods. Methods Page 9

We distinguishedtwo different typesof datesof first record.The first and preferredtype is the dateof initial plantingor first observationor collectionof the speciesin the area.Where this was unavailable, we reportedthe earliest date available date of writing, submissionor publication! of the first written accountof thespecies in the area.In Table1, dates of first writtenaccount are preceded by the symbol'<', meaningthat thedate of first planting,observation or collectionwas on or before in some cases,perhaps a considerabletime before! the indicated date. Dates of first written account were excluded from the quantitative analysis. We also excluded from the analysis those dates of first record that we judged to be a clear artifact of collecting bias, or a fortuitous discovery of a speciesin a restrictedhabitat or locality, and whoseinclusion would have contributed to a misleadingpicture of the temporalpattern of invasionsin the Estuary.This is discussedfurther in ChapterS under"Results." These dates are markedby asterisks '! in Table 1.

4. TRANsFoRT MEcHANksMs We analyzedthe stocksof organismsthat havebern introducedto the Estuary in terms of the transport mechanisms also called "transportvectors," "means of introduction" and "dispersalmechanisms"! that brought them to the northeastern Pacific.We utilized thirteen categoriesof mechanisms,as definedin Table l and discussedin Chapter5 under "Results."Where multiple possibletransport mechanismswere determinedfor an organism,that organism'scount was divided proportionally among the possiblemechanisms. Page10

CHAPTER 3. INTRODUCED SPECIES IN THE ESTUARY

PLANTS

SEAWEEDS

Bryopsissp. [CODIALKS] Silva979! reportedan unidentifiedspecies of Bryopsiswhich only reproducesasexually in theBay and which he described as exhibiting weedy behavior:developing explosively and frequently being cast ashore in large quantities,creating a nuisanceasit decomposes.It has been observed in theBay sinceat least1951, from to Richmond on the shore and at Point, Bryopsisoccurs in ship fouling pers.obs.! and, in concertwith the other introducedseaweeds, we tentativelysuggest ship fouling as the mechanism of introduction.

Codr'umfragilk tomkntosoidks suringar, 1867! Hariot, 1889 [CoDIALEsj

DEAD MAN'S FINGERS,SPUTNIK WEED, OYSTERTHIEF

Codiumfragile is native to the northern Pacific,and is found in North Americaon exposed coasts from to BajaCalifornia Abbot & Hollenberg, 1976!.The weedy subspecies C.f. tomentosoiCksisnative to Japan where it iseaten! andwas introduced toEurope in thenineteenth century and to New York, probably asship fouling,around 1956, subsequently spreading north to Maineand south to NorthCarolina Carlton k Scanlon,1985; includes discussion of coastal transport mechanisms!,It was first collected in San Francisco Bay in 1977,probably introduced asship fouling Carlton et al., 1990!, and as of 1985not reported from any other site in the northeasternPacific Carlton & Scanlon,1985!. In SanFrancisco Bay C. f. tomkntosor'desis common intertidally and subtidallyattached to rocks,seawalls, piers and floating docks. Josselyn & West 985! reportit ascommon found 60-100% of the time! at Coyote Point, and frequent0-60%! atRedwood City, Palo Alto. In 1993-94 wefound it on floating docksin theEast Bay from Richmond to SanLeandro and at Pier39 in San Francisco.

Sargassummuticum Yendo, 1907! Fensholt, 1955 [FUCALES] Sargassummuticum is a Japanesespecies which was first collected in North Jntroduced Species Page 11

Americain 1944in , apparentlyintroduced in shipmentsof Japaneseoyster spat Crassosfrea gigas!, and subsequently spread both north and southinto protected waters. It wasreported from Coos Bay in 1947,Crescent City in 1963and SantaCatalina Island in 1970,and is now found at scatteredsites from Alaskato Baja California Abbott & Hollenberg,1976; Silva, 1979!. It was introduced toEurope in the early 1970s, apparently also in shipmentsof Japanese spat Druehl,1973; Critchley, 1983; Danek, 1984!. S. modicumwas first observedin SanFrancisco Bay by Silva on the riprap at theentrance to theBerkeley Marina in 1973It hasbeen reported on the pilings of theGolden Gate Bridge, in the San Francisco Yacht Harbor, on the inside breakwater atFort Baker, at Angel Island, Sausalito and the Tiburon Peninsula, onthe east side of YerbaBuena Island, at CrownBeach in Alameda,and froxnAlbany and Richxnond Silva, 1979; Danek, 1984!. Josselyn & West 985! found it commonly0- 100/o of the time!at TiburonPeninsula and infrequently -30'/o! at Twin Sisters. In SanFrancisco Bay S. muticum appears to berestricted to low intertidal areaswith hardsubstrate and moderate to high salinity.Germlings grow at salinities downto 10ppt to20 ppt according toNorton 977!!, but maxixnum survival is at 25-30ppt salinity. Low salinities and storms eliminated the Tiburon population in thewinter and spring of 1983 Danek, 1984!. S. muticum was more abundant at CrownBeach, Alameda during the droughtyears of 1990-91than it is at present pers.obs.!. Bothlateral branches and fertilefronds of S.m~ticxxm break off regularlyand floatand disperse by currents and wind drift, surviving afloat for up to 3 months, andcan initiate new populations Danek, 1984!. Danek 984! reportsthat "in Britain S.muticum has become the dominant species at low tidelevels, and is a successful competitoragainst indigenous species such as Cystoseira andLaminaria...it forms largefloating mats Fletcher & Fletcher, 1975! causing problems for fishermen and smallboat navigation." An eradicationprogram in Englandwas "largely unsuccessful" Silva, 1979!. In Canada,Druehl 973! considersit to be replacing populationsofZostera in some places, and Dudley & Collins995! report that it has becomea dominantintertidal species in the ChannelIslands and Santa Barbara area. However,Silva 979! statesthat "thereis no evidencethat S. muticumis displacing the native biota of San Francisco Bay."

Callithamnianbyssoides Arnott [CERAMIALESj Callithamniorrbyssoides is native to the northwesternAtlantic from Nova Scotiato Florida Taylor, 1957!. It was not listed in Silva's979! review of Central Baybenthic algae, but Josselyn Q West 985! found it attached torocks "near MLLW throughoutthe northern and southern reaches of the bay" in collectionsbetween 1978and 1983. They report it asfrequent found 30-6 P/oof the tixne! at Redwood City,Palo Alto and Camp, and infrequent -30/a! at Tiburon Peninsula, Point Irttrodueed Species Page12

Pinole and Crockett. Callithamnion species are common fouling species W+Qi, 1952!.C. byssoidesmay havebeen transported to SanFrancisco Bay as ship fouling, or possiblywith the algaeused to packNew Englandbait worms or lobster.

Polysiphoniadenttdata Dillwyn! Kutzing [CERAMlALES]

Polysiphoniadenttdattt is native to the Atlantic coast from Prince Edward Island to Florida and the tropics, commonly occurring in pools and in shallow baysattached to rocks,shells and wharves Taylor,1957!. It wasnot listed by Silva 979! in his reviewof CentralBay benthicalgae, but Josselynk West 985! reported it as a "common drift algae during summer months, especially in South San FranciscoBay" citing Cloem, pers. cornIn.!, and as drift or epiphytic in both San PabloBay and SouthBay in collectionsbetween 1978 and 1983.Mey further suggest that "the extensive decaying mats observed by Nichols 979! in Palo Alto during the summer of 1975" may have been P. denttdattLWe OTC! observed a sometimes abundant Polysiphonia,which we presume to have been P. dt.nudafa,in , Oakland in 1963-64. Polysiphoniaspecies are common fouling speciesor artificial structures, including ships WHOI, 1952;Fletcher et al., 1984!,and a speciesof Polysiphoniawas the organism most tolerant of copper- and mercury-based anti-fouling compounds in tests in Florida Weiss, 1947!, suggesting that P. den~dataprobably arrived in San FranciscoBay as hull fouling, although introduction by ballast water is possible. Josselynk West 985! reportedP. denudutaas frequent0-60% of the time! at Point Finole, and mfrequent -30%! at stations on the western shore of the South Bay, on the Marin shore, and at Crockett. It apparently reproducesasexually in San Francisco Bay, and is not reported from other Pacific coast estuaries M. Josselyn,pers. comm., 1985}.

VASCULAR PLANTS

Chenopodittrnmacrosperetttm J. D. Hooker var. halophilum Philippi! Standley [CHENOPODIACEAE] SYNONYMS:Chenopodittm macrospermttm J. D. Hooker var. farinosum Watson! Howell

Probablynative to SouthAmerica, this plant is found in wet placesand marshesat low elevationsbetween Orange County and Washingtonstate, including the coastalCalifornia Munz, 1959!the SanFrancisco Bay Area and the Delta Hickrnan, 1993!. Introduced Species Page13

Cotulacoronopifolia Linnaeus, 1753 [ASTERACEAE]

BRASS BUTTONS

Brass buttons is a native of South Africa that has become established along the pacific coast from California to British Columbia, and is reported as adventive in NewEngland Peck, 1941; Muenscher, 1944; Steward et al., 1963!. In 1878,Lockington 878! reportedit asan introducedplant common in wet placeson the SanFrancisco peninsula.As it waslikely to havespread to theBay's littoral zone by aroundthat time, we have taken 1878as the date of first observation in the Estuary. It was probablyintroduced in ships'ballast assuggested by Spicherk Josselyn,1985!. In California brassbuttons has variously been reported as common in salt and freshwaterrnarshes along the coast Robbinset al., 1941;Mason, 1957; Munz 1959; Hickman,1993!, as presentin SanFrancisco Bay saltmarshesOepson, 1951!, as commonin wet placesnear high-tide levelsin the tidal marshesaround SuisunBay Atwater et al., 1979!,and as uncommonin the Delta MadroneAssoc., 1980; Herbold k Moyle,1989!. A 1981aerial survey of SuisunMarsh classified 3/00 acres,or 5%of- the areasurveyed, as Cotvla habitat tN'ernette,1986!, and in 1989it was found at 18 of 48 sites.Along with alkali bulrush, saltgrassor fat hen, brassbuttons comprised theprincipal vegetation at two sitesin eachof 1987,1988 and 1989 Herrgeseli, 1990!. Waterfowlfrequently graze on brassbutton seeds,and the diked,brackish marshes aroundSuisun Bay are managedin part to promoteits growth Oosselyn,1983!.

Lepidiumlatifolium Linnaeus [BRASSICACEAE]

BROADLEAF PEPPERGRASS,PERENNIAL PEPPERWEED, TALL VMITXTOP

Broadleafpeppergrass is a nativeof Eurasia,where it is reportedfrom Norway to North Africa and east to the Himalayan region. It has been introduced to many parts of the United States,Mexico and Australia,and is found on beaches,tidal shores, saline soils and roadsides throughout most of California Hickman, 1993; Youngk Turner, 1995;May, 1995!.Suggested mechanL~zns of transport to North America along the coast prior to 1924include transport in gluestock animalbones! shipped from Europe,the seedsadhering to scrapsaf tissue or burlap sacking Morse,1924, cited in May, 1995!;with materialshipped to a dyeand licorice works Eames, 1935,cited in May, 1995!;and clinging to the wool of sheep Rollins, 1993,cited in May, 1995!. Broadleafpeppergrass was discoveredin Montanain 1935,and in California near Oakdale, StanislausCounty in 1936,possibly having been transported with beet seed May, 1995!.By 1941it was reportedfrom SanJoaquin and Yolo countieson the edgeof the Delta Robbinsef al., 1941!.Herbarium specimens exist from collected in 1960!,Antioch Dunes 977! and the Bay shoreline at Martinez and Point Pinole 978!. It was reported as common in the tidal marshes of the San FranciscoEstuary Atwater et al., 1979!,and uncommon in the Delta Madrone Assoc.,198G, Herbold R Moyle,1989! Recentlyit hasbeen reported as invasiveand IntroducedS peer'es Pagel4 spreadingin shallowponds and adjacent moist uplands in theCentral Valley refuges, and in high tidal marsh areas and diked seasonalwetlands in SuisunMarsh wherehundreds of acreson Grizzly Island are affected!and throughoutthe Bay Trurnbo,1994; Dudley k Collins,1995; Malarnud-Roam, pers. comm., 1994;May, 1995!. Broadleafpeppergrass produces large amounts of seed,can reproduce asexuallyby spreadof rhizomesections, and is tolerantof a broadrange of environmentalconditions Trumbo,1994; May, 1995!.It oftenbecomes established ondisturbed, bare soils, and was also observed in pickleweed Salicornia! plains and amongSnrpus spp. May,1995!. May 995! reportsthat it maybe intolerantof frequentor prolongedflooding, and our observationssuggest that it is limited to the upperedge, or often abovethe upperedge, of tidal inundation. Trumbo994! suggeststhat at SuisunMarsh peppergrass first gotestabbshed in agriculturalareas, then as farms closed during the 1950s expanded rapidly "uncheckedby frequent cultivationsand crop competition"and invaded wildlife areasof the marsh.He claunsthat it competeswith pickleweed,thereby reducing habitatfor theendangered saltmarsh harvest mouse, and that its densegrowth is unsuitablefor useas nesting cover by waterfowl,although May 995! reportsthat waterfowlnests have been observed in rnonotypicstands of peppergrass.BDQC 994! statesthat it mayoutcompete and displacecertain rare native marsh plants, such as Litaeopsismasoni and Cordylanthus mollis moltis. CDFG has tested burning,discing and herbicide treatments as control measures for pepper grass, which is ranked as a "B"-levelplant pestby the California Departmentof Food and BDOC, 1994!.

LimOSeoaSubulata IveS, 1817ISCROPHULARIACEAEj

A WL-LEAVED MUDWORT

Limose/Iassbulata is native to Europe or the east coast of North America, and found in southernBritish Columbiaand in fifteen westernstates. It is reported from muddy and sandy intertidal flats in the Delta Muenscher, 1944; Munz, 1959; Atwater et al., 1979;Herbold ik Moyle, 1989;Hickrnan, 1993!.

Lythrum saticariaLinnaeus [LYTHRACKAE!

PURPLE LOOSEST$HFK

Native to Europe, purple loosestrife is invasive worldwide. It was introduced to North America by the early 1880s,either as seedsin solid ballast or in the wool of sheep,or as a cultivatedplant. It cangrow in monospecificstands, competes with cattails and other marsh plants Mills et al., 1993!,and is listed as a noxious weed in California Hickrnan, 1993!. Page15 Introduced Spectes Purpleloosestrife wasreported byMunz 968! in Nevada andButte counties butnot mentioned byMunz 959! or Mason 957!. It isnow found in low elevationmarshes, ponds, streambanks andditches throughout much of California, includingtheSacramento Valleyand the Bay Area Hickman, 1993!. Myriophyllumaquaticum Velloso! Verde. [HALORAGACEAE]

PARROT'S FEATHER SYNONYMS:Myriophyllrrm brasiliense Cambess. A SouthAmerican native, parrot's feather isfound in ponds, ditches, andlakes inwarm temperate andtropical regions throughout theworld. Escaped fromcultivation inCalifornia andreported from six counties from Humboldt to SanDiego "set outin these areas bydealers inaquatics forthe purpose ofmarket propagation;"Mason,1957!,from the Coast andCascade rangesand from central westernCalifornia Hickman, 1993!, and from tidal rnarshes andsloughs inthe Delta Atwater etal., 1979; Madrone Assoc., 1980!. BDOC 994! reports thatparrot's feather"provides excellent habitat," andthat the USDA hasinvestigated theuse of herbicidaland biological controls.

Myriophytlumspicatum Linnaeus [HALORAGACEAEj

EURASIAN MILFOIL SYNONYMS:Myriophyllum exatbescens in part Eurasianmilfoil isa nativeofEurasia and North Africa that has invaded lakesin the eastern United States and Canada. Itsfirst documented occurrence in NorthAmerica was in the Potomac River, Virginia in1881, though it is thought to havearrived much earlier Reed, 1977, cited inMills et al., 1993!. Inthe early 1970s it reportedlymadeupover 90percent ofthe plant biomass inLake Cayuga, NewYork, whereitmay have been eventually controlled byan exotic moth, Acentria niveous Anon.,1994! Control efforts have also included cutting, water drawdown and herbicideapplications Millset al., 1993!. Eurasian milfoil reportedly canoutcompete nativeplants through shading, clogpipes andentangle boatpropellers, andfoul beacheswithdecaying matsof dead plants. Itspreads asdiscarded material from aquariaandentangled onboats andtrailers moved between watersheds MiQsetal., 1995!. Hickman993! reports this plant as uncommon inditches and lake margins inthe Bay Area and the , andBDOC 994! reports itfrom the Delta.Munz 959! reported Myriophytlum spicutum ssp. exalbescens common throughoutcismontane California inquiet water below 8,000 feet, Atwater etal. 979!reported M.s. ssp. exalbescens inSnodgrass Slough onthe Introduced Species Page 16

in the Delta in 1976,and MadroneAssoc. 980! reportedwater milfoil as M. s. var. exalbescensand M. exalbescens!common in the Delta. Hickman 993! statesthat M s. ssp. exalbescenswas misapplied to M. sibiricum, which he treats as a native butwhich we consider cryptogenic Table 2! basedon itsreported range which includesPacific coastal and easternNorthern America and Eurasia!. Based on reported distribution and abundance,we considerMunz's 959! exalbescensto be M. sibiricumand the Delta reports of exalbescenssince 1976 to refer,at least in part, to M. spicatum.

Polygonumpatulum Bieberstein [POLYGONACEAEJ

SMARTWEED

Native to easternEurope, Polygonum patulum is reportedas uncommonin andaround salt marshes in the Bayand Delta area Munz1959; Hickman, 1993!. It belongsto a closelyrelated andpossibly hybridizing! group of introducedor cryptogenicspecies, often found in or adjacentto freshor salinewetlands, mcluding Polygonumaviculare cryptogenic!, argyrocoleon Asian!, prolificum easternNorth America! and punctatum cryptogenic!.

Rorippanasturtium-aquaficum Linnaeus! Hayek fBRASS1CACEAE]

WATERCRESS

SYNONYMS:Nasturtium Officinale R. Br. Radicula nasturtium-aquaticum Linnaeus! Britt k Rendle Rorippa nasturtium Rusby Sisymbrium nasturtium-aquaticutn

Watercressis a perennialaquatic plant native to Europewhich hasbeen widelycultivated for its ediblegreens, and which has escaped and become common throughoutNorth America in rnarshes,in slowlyflowing creeks, around seeps, on wet banks,etc. Though probably presentearlier, established populations were first reportedfrom North Americanear NiagaraFalls in 1847and at Ann Arbor, Michiganin 1857 Gray, 1848;Green, 1962; Mills et al., 1993!.Peck 941! reportedit widely distributedin Oregonand Muenscher944! reportedit from 41states including California, Oregon and Washington. Watercressis found in the Delta Munz, 1959;Herbold k Moyle, 1989!.Most authors e. g. Jepson,1951; Munz, 1959;Mills et al., 1993,1995; BDOC, 1994!consider this plant to be an introductionfrom Europe, although Hickman 993! treatsit asa native plant of temperate world-wide distribution. Introduced Species Page 17

Salsolasoda Linnaeus [CHENOPODIACEAE] Native to southern Europe,Salsota soda is found on mudflats, in open areas andamong pickleweed in saltmarshes, and on berms,among riprap and in open areasat and abovethe high tide mark at scatteredsites in SanFrancisco Bay Hickman,1993; pers. obs.!. It was first collectedin July 1968at the west end of the DumbartonBridge in the SouthBay Thomas,1975!, It has sincebeen found at severalsites in the SouthBay from CandlestickPark to the SanFrancisco Bay National Wildlife Refuge,and on the Alameda shore;from EmeryvilleMarina to HoffmanMarsh, Richmondand at RichardsonBay in the CentralBay; and at ChevronMarsh, Richmond,at Pinole and at in SanPablo Bay Thomas,1975; Tamasi, 1995; pers. obs.!. At the Pinoleshore it appearsto be successfullycompeting with pickleweed Salicornia virginicu in thehigh marsh, and likepickleweed isattacked by the parasitic plant Cuscufa salina pers. obs.!. A few plantswere observed on a mudflatin BodegaHarbor in thesummer of 1994but not in 1995 Connors,1995; C. Daehler,pers. comm., 1995!. Its mechanismof introductionis somethingof a mystery,as no known moderntransport vector excepting the unlikely possibility of its use andescape! as an ornamental plant appears to apply.

S pergutariamedia Linnaeus! Grisebach [CARYOPHYLLACEAE]

SAND SPURREY

SYNONYMS: ria media Hickman 993! noted that "Spergutaria marifima AII.! Chiov. may prove to be the correct name" for this species.

Sand spurrey is native to coastal Europe and has been introduced to South America, eastern North America and Oregon. It is found on salt flats, in and borderingsalt marshes,and on sandybeaches in Marin and ContraCosta counties Munz, 1959;Hickrnan, 1993!.Atwater et al. 979! bsted it as common in tidal rnarshesof the San FranciscoEstuary.

algeriadensa Planchon [HYDROCHARITACEAE]

ELODEA, EGERIA, BKMILIAW WATERWEKD

SYNONYMS:Elodea densa Planchon!Caspary Anacharis densa Planchon! Marie-Victorin 1ntroducedSpecies Page1B Elodeaisa highlyinvasive from South America that clogs waterwaysand interferes with navigation. In 1944 Muenscher reported it as a recentlyestablished introduction in six eastern states from Massachusetts toFlorida andin California,Steward etal. 963! reported it from Oregon, ancl it hasalso becomeestabhshed inEurope Hickman, 1993!. It is widely used in aquaria and ornamentalpools,and was probably introduced asdiscarded material oras an escape Muencher,1944; Munz, 1959!. InCalifornia it was reported asinfrequent atscattered locationsbyMason 957!, and is now found on both sides ofthe , in theSan Joaquin Valley, and in the San Francisco Bayarea Hickman, 1993!. Elodeaisreported ascommon in waterways throughout the Delta and in the ContraCosta Canal Atwater etal., 1979; Herbold 6zMoyle, 1989; Holt, 1992! It was foundat 8 of10 sites in the Delta surveyed forlittoral zone vegetation in1988-90 IESP,1991!. In the1990s it has spread tonew areas and deeper water in the Delta and becomemore abundant, perhaps due to lower summer water levels and warmer watertemperatures Holt, 1992; Thomas, pers. comm.!. Although elodea provides shelterfornewly hatched fish, it alsoclogs channels andberths, gets caught inwater intakeof engines,and fouls propellers. Management ofthis species included the use ofan aquatic weed killer on about 35acres ofDelta waterways in1991 Holt, 1992!. Fieldtests are being conducted onthe use of Komeen, a copper-based herbicide, and biocontrolagents are being investigated Rubissow, 1994, BDOC, 1994!.

Eichhorrjiacrussipes Martius! Solms-Laubach, 1883fPoNTEDERIACEAEJ

WATER HYACINTH Waterhyacinth, "perhaps the world's most troublesome aquatic weed" {Hickman,1993! isa nativeoftropical South America that has spread tomore than 50countries onfive continents, andhas become a massive problem inwaterways in bothAfrica and Southeast Asia Barrett, 1989!. Itsair-filled tissue aerenchyma! enablesit to floatand spread rapidly within and between connected water bodies. It reproducesasexually bybreaking apart into pieces each of which develops into a separateplant. This results in a rapidmcrease in biomass,and continuous mats of livingand decaying water hyacinth upto two meters thick covering thewater surfacehave been reported Barrett, 1991!. Waterhyacinth was introduced to NorthAmerica in 1884via theCotton StatesExposition inNew Orleans. The plant was displayed inornamental ponds anddistributed assouvenirs tovisitors, with the excess dumped into nearby creeks andlakes Barrett, 1989; Joyce, 1992!. It spreadacross the southeastern U.S. to Florida,where a 1895invasion ofthe St. Johns River produced floating mats of waterhyacinth up to 40kilometers long Barrett,1989!, and in severalsoutheastern sitesblocked the passage ofsteamboats andother vessels by1898 Ooyce, 1992!. AccordingtoJoyce, these problems led to thepassage of the River and Harbor Act in 1899,authorizing the U. S. Arxny Corps of Engineerstomaintain navigation channelsin these areas. Control efforts included the spraying ofsodium arsenite, whichpoisoned applicators and livestock Ooyce, 1992!. introduced Species Page19

The1884 Cotton States Exposition was probably also the initial sourceof the waterhyacinth that was reported from the Sacramento River near Clarksburg, California,in 1904 Thomas & Anderson,1983; Thomas, pers. comm., 1994!. In California,water hyacinth spread gradually for manydecades. Robbins et al. 941! reportedit from the in FresnoCounty and Warner Creek in San BernardinoCounty. It reachedthe Delta by thelate 1940s or early1950s, where the federalBureau of Reclamationtried controlling it with herbicidesaround 1957 Thomas& Anderson,1983; L. Thomas, pers. comm., 1994! In 19S9Munz reported it asoccasionally established in sloughs and sluggish water in theSacramento antiSan Joaquinvalleys and the system. In1972 the U. S. Army Corps of Engineersinvestigated water hyacinth on the and determined that it wasnot a floodhazard Thomas& Anderson,1983; L. Thomas,pers. comm., 1994!. Atwateret al. 979! listedit ascommon in tidal marshes,presumably in theDelta. MadroneAssoc. 980! reportedit asseasonally common in thesouthern and central Deltaand clearing in thewinter, when coot and other waterfowl fed on thedead plants. Startingin the1980s water hyacinth became a seriousproblem in theDelta watershed,blocking and waterways, fouling irrigation pumps, shutting down marinas,blocking sahnon migration and, by 1982-83,blocking ferry boats at Bacon Islandand preventing the island's produce from being shipped to market CDBW, 1994;L. Thomas,pers. comm., 1994!. The plant's abundance may have been drought- related,with plantdensities building up whenlow riverflows were unable to Gush theyear's growth out of theDelta. Qn the other hand, when a wetyear arrived in 1993the higher rainfall "washed surplus plants from the upstream channels into theDelta where it createda majorproblem by earlysurnrner, and it alsoappeared to triggerunprecedented seed growth." High flows also lowered chloride levels enablingplants to grow in partsof thewestern Delta that had previously been clear CDBW, 1994!. On June14, 1982 California Senate Bill 1344became law, directingthe CaliforniaDepartment of Boatingand Waterways CDBW! to controlwater hyacinth in the Delta.CDBW set up barriersto keeplarge masses of floatingplants out of navigationchannels and sprayed the herbicides Weedar ,4-D!, Diquatand Rodeo glyphosphate!,at a costthat roseto about$400,000 annually. program Supervisor LarryThomas claims that if herbicideshad not beenused in 1986-1991,"water hyacinthwould have shut theDelta down" L. Thomas,pers. comm., 1994! In someareas mechanical harvesting has been used to controlhyacinth, but this is expensive typically around $1+00 to $3,000per acre! and disposal of the hyacinthcan be a problem.Because of the cost, CDBW does not use mechanical harvesting L. Thomas,pers. comm., 1994!, In 1982and 1983 CDBW, working with the U. S.Department of Agriculture, importedand released three insects from South America as biological controls, the moth Sameodesalbiguttatis which did not survive!and the weevilsNeochetirra bruchiand N. eichhorrtiae.Although the two weevilsbecame established in the Delta, there is no evidencethat they control water hyacinth Thomas& Anderson, 1983;L. Thomas,pers. comm., 1994!. Introduced Species Page20

Of thethree flowering forms of waterhyacinth, only medium-style plants havebeen found in Californiaeven though these plants are heterozygous for style lengthThis suggests that water hyacinth does not reproduce sexually in California. Conditionspreventing sexual reproduction may include a lackof effectiveinsect pollinatorsforaging in hyacinth although honeybees Apis mellifera may be effectivewhere they visit hyacinth!,and a lackof openshallow water or saturated soil siteswhich areneeded for germinationand seedling establishment Barrett, 1980, 1989!. Todaywater hyacinth is locallyabundant in ponds,sloughs and waterways in theCentral VaHey, the Bay Area, and the southern Coast and Peninsular ranges Hickman,1993!, and very densein many waterwaysin the Delta.In 1988-1990it was foundin 4 of 10sites in the Deltasurveyed for littoral zonevegetation IESP, 1991!. In 1993hyacinth again became very dense in partsof theDelta and the San Joaquin Valleydrainage, despite herbicide treatment of around1,500 acres CDBW, 1994!. In the , the leaves of this troublesome weed are sold as a market vegetableunder the nameof "waterlilly" or "" Ladinesik Lontoc,1983!.

Iris pseudacorusLinnaeus [IRIDACEAE]

YEI.LOW FLAG, YELLOW IRIS A nativeof Europe,Iris pseudacoruswas a populargarden flower that escaped from cultivation. The first populationsreported in North Americawere from near Poughkeepsie,New York in 1868,from a swampnear Ithaca,New York in 1886and from Massachusettsin 1889,and it wasfirst reportedfrom Canadaat Ontarioin 1940 Mills et al., 1993,1995!. It is now widespreadeast of theRocky Mountains Hickman, 1993!. Jepson951! did not mentionIris pseudacorus,but Mason957! reported that it "hasescaped in MercedCounty and is apparentlymoving down the watercourses."It has sincebeen found in irrigation ditchesand marginsin the SanFrancisco Bay area, in the southernSan Joaquin Valley, and in SonomaCounty Munz, 1968;Hickman, 1993!.Atwater 980! found it wasthe only common introduced plant on Delta islets, reportmg it from the banks of 4 out of 6 islets surveyed in 1978-79.

Polypogonelongates Kunth, 1815 fPOACEAEJ

Native to South America, this plant is found in salt marshes and on sand dunesin the Bay Area, including ContraCosta County, and in the southernCoast Range Munz, 1959,Hickman, 1993!. Introduced Species Page 21

Potamogetoncrispits Linnaeus, 1753 [POTAMOGETONACEAEj

CURLY-LEAF PONDWEED,CURLY PONDWEED Thispondweed is nativeto Europeand now found more-or-less worldwide, includingAtlantic North AmeriCa,, California and Oregon Steward et al.,1963!. The earliest verified records in North America are from Delaware and in the1860s, although reports of it dateback to 1807.It wasdeliberately introduced into partsof the Great Lakes basin to providefood for waterfowl, and is associatedwith fishhatcheries having perhaps been accidentally transported between watersheds in conjunctionwith fishstocking activities Mills et al.,1993 citing Stuckey, 1979!. It reportedlycan grow in fresh,brackish or saltwatei' Mills et al.,1995!. It is uncommonin shallow water, ponds, reservoirsand streamsacross most of cismontaneCalifornia including the Bay Area and the Central Valley Munz, 1959;Hickman, 1993!. In 1988-90it wasfound in 2 of10 sites surveyed for littoral zonevegetation in theDelta IESP,1991!.

Spartinualterniflora Loiseleur-Deslongchamps [POACKAE]

SMOOTH CORDGRASS,SALT-WATER CORDGRASS Spartinaalterniflora is native to the coastof easternNorth Americafrom to Texas Muenscher,1944! and hasbeen mtroducedto PadiilaBay 910!, ThorndykeBay 930!, Camano Island and Whidbey Island in Washington;the SiuslawEstuary in Oregon;and New Zealand, England 922! andChina 977! Chung,1990; Callaway, 1990; Cailaway & Josselyn,1992; Ratchford, 1995!. Most literature statesthat S. alterniflorawas first introducedto the northeasternPacific in WillapaBay, Washington, but both the dateand mecharusmof introductionto this site areunclear, In a briefnote Scheffer945! reportedfirst becomingaware of a cordgrassin WillapaBay "about seven years ago" thus about1938 that was identified as S. alterniflorain 1941.An oystermanreported first seeingthe plants "about1911," and Scheffer,believing that the first Atlantic shippedfrom RhodeIsland! had been planted in WillapaBay about 1907, concluded apparently basedon the coincidencein dates!that thecordgrass had been introducedwith the oysters. Sayce988! pointedout that Schefferwas mistaken about the initial dateand originof Atlanticoyster shipments to WillapaBay, reporting that in factthe first shipment,of 80barrels of oystersfrom estuariesnear New York City and ChesapeakeBay, occurred in 1894,and that therewere no subse

allernifloraor S.patens. S. parenshas not beenfound in WillapaBay. Either viable seedsor rhizomesof S partinaalterniflora were in thepackmg material." Nearly all subsequentauthors have followed Sayce in reportingthat S. alterniflora arrived in Wiilapa bay in 1894as packing materialfor oysters.However, we havefound no recordof cordgrass ever having been used as packing material for any oyster shipments,nor is thereany reason to thinkthat hard-shelled oysters packed in barrelswould need or benefitfrom additionalpacking. Thus, there is no basisfor concludingthat S. alterniflora was introduced to WillapaBay in 1894. Accordingly,we consider the first record of S.alterniglora in Willapa Bay to be "about1911," and suggest solid ballast as the likeliest transport mechanism. Moleculargenetic comparisons with east coast populations may clarify the source of theS. alterniflora stock in WillapaSay as has been done for San Francisco Bay S. alterniflora;C Daehler,pers. comm., 1995!, providing additional information to resolvethe probablemeans of transport. Sparfinaalfernif10ra was separately introduced to SanFrancisco Bay in. the early1970s by theU. S.Army Corps of Engineersas mitigation for destroyedin the constructionof the New AlamedaCreek Channelor asan experimental planting anecdotal accounts and genetic analysis both indicating thatthe stock originated from Maryland;C. Daehler,pers. comm., 1995!. It was plantedat Pond3 atthe Coyote Hills Regional Shoreline. One source reported that afterplantings of thenative cordgrass S.foliosa did poorly,the area was replanted with the more robust S. alterniflorato producea "successful"restoration. S.alterniflora froxn Coyote Hills waslater transplanted to SanBruno Slough nearthe San Francisco Airport by theCaltrans agency, either as mitigation for the SamtransBus Terminal or for erosioncontrol. It xnayalso have been planted in the ElsieRoexner Wildlife Refuge on thesouthwest shore of AlamedaIsland as part of yeaanother "restoration" project in 19S3or 1984,or for erosioncontrol by theCity of Alaxneda,It was found in HaywardMarsh in 1989 Spicher tk Josselyn, 1985; Calloway,1990; Kelly, pers. comm., 1992; Faber, pers. comm., 1993; Taylor, pers. comm., 1993;Cohen, 1993!. In SanFrancisco Bay S. alternifloruis foundboth within existingsalt marshes andextending into lower elevationmudflats. Comparing aerial photographs of the xnouthof CoyoteHills Slough,Callaway 990! sawno S.alterniflora in 1981but counted31 round patches in 1988and 146 patches in 1990.Daehler k Strong994! foundthat "although some dense monocultures have formed," xnost S. alternif1ora wasgrowing in discretecircular patches separated by openmud, determinedby isozymeanalysis to consistof individual geneticclones. There are now a total of about 1,000round or donut-shapedpatches at southwesternAlameda Islan.d and northeasternBay Farm Island, SanLeandro Bay, Hayward Marsh,Alaxneda Creek andCoyote Hills Slough New AlamedaCreek!, and San Bruno Slough nearthe SanFrancisco Airport!. Smalleramounts are reported from the Estudillo Flood ControlChannel south of the SanLeandro Marina, the SanFrancisco Bay National Wildlife Refugeand the Cargill salt ponds near Newark, and the National Wildlife Refugenear Alviso M. Taylor,pers. coxnxn., 1993; J. Takekawa,pers. conun., 1994; C. Daehler, pers. comm., 1995!. Page23 Introduced 5pecies Newpatches of S. alternigora areestablished both from seed and vegetative fragments Daehler & Strong, 1994!. The cordgrass apparently arrived inHayward as floatingrhizornes M.Taylor, pers. coxrun., 1993! and may be spread bydredges withinthe Cargill salt ponds D. Strong, pers. comm., 1993!. Daehler & Strong994! observedabout 75 percent of patchessetting very little seed in 1991-1992,and germinationratesranging from zero to 59 percent, andsuggested thata fewclones maybe producing most of the seeds. Onthe other hand, Callaway 990! found higherseed production ,475 vs. 371 seeds/m2!, higher seed viability 9T/< vs. 67 /0! andhigher germination rates average germination percentages of77/o vs. 49/o in freshwater,and 37% vs. 14'/o in 25ppt salinity! for S.alterniflora than for thenative cordgrassSpartina fotiosa in SanFrancisco Bay. S partinaalterniflora grows both higher and lower in theintertidal zone than S.fotiosa Calloway, 1990; D.Strong, pers. comm., 1993; inWillapa Bay its total verticalrange is atleast 66 percent ofthe tidal range, Sayce, 1988!, and can accrete sedimentata rapidrate Sayce, 1988; Josselyn etal., 1993!. By growing ata lower elevationit may reduce the area of mudflats in San Francisco Bay as it hasin WillapaBay, Washington, whereit has turned an estimated 1,800-2,400 acres-6 percent!ofWillapa Bay's rnudflats into cordgrass islands Ratchford, 1995!. Callaway & Josselyn992! listed potential adverse impacts as:competitive replacement of nativecordgrass; altered habitat for native animals because oflarger and morerigid stems and greater stem densities; altered habitat for infauna because of higherroot densities; changed sediment dynamics; decreased benthic algal productionbecause oflower light levels below cordgrass canopy; andloss of shorebirdforaging habitat through colonization of mudflats. In British estuaries, the invasionofmudflats by Spartina angh'ca has produced adverse effects on shorebirds Goss-Custard& Moser, 1990; Callaway, 1990!. Thepotential loss of native cordgrass is of particular concern, because it provideshabitat for the severely endangered California clapper rail, Rallies longirosfrisObsoletus. Onthe other hand, S. allerniflora could possibly provide moreand better cover and thereforebetter protection for the rail, which is threatenedbypredation by theintroduced red fox, Vutpes vulpes P. Kelly, pers. comm., 1992;Cohen, 1992, 1993!, In SanFrancisco Bay, S. alterniflora is attacked by the sap-feeding planthopper Proketisiarnarginata atdensities ranging from 116 to 332 insects per inflorescence! muchhigher than typically observed onthe Atlantic coast, and by the sap-feeding rniridbug Trigonohjtus uhleri. However, this does not appear to affect growth rates, seedproduction or germinationrates Daehler & Strong,1994, 1995!. TheCalifornia Department of Fish and Game elirnmated S.alfernifloru from HumboldtBay in about5years by constructing a dike around a clump"the size of a house"and covering it with black plastic, ata costof $30,000 to$40,000 h4. Taylor, pers.comm., 1993; D. Strong, pers. comm., 1993!. Burning and herbicides have been triedin GreatBritain P. Kelly, pers. comm., 1992!. After trying weed eaters and. burning,the East Bay Regional Park District's current control strategy atHayw'ard Marshis to coverwith black plastic. The herbicide Rodeo glyphosphate! hasbeen usedat San Bruno Slough. Smooth cordgrass has now so thoroughly clogged the NewAlameda Creek Flood Control Channel the projectfor whichthe plant was Introduced Species Page24

originally introduced as mitigation! that the Army Corps has proposed 5 years of helicopter-spraying Rodeo in the channel P. Baye,pers. comm., 1994!.

Spartinaartglica C. E. Hubbard, 1968[POACEAEj

ENGLISH CORDGRASS

The western Atlantic cordgrass Spartinaalternigora n=62!was introduced in ship ballast to Southampton Water on the south coast of England, where it was collected in 1829.S. alterrriflora there hybridized with the British cordgrass S. maritima n=60!, producing a sterile Fl hybrid known as S. townsendii or S. x totvnsendiin=62! which was first collectedin 1870near Southampton,though not recognizedas a hybrid until 1956.Chromosome doubling in this hybrid produceda fertile form n=l20-124!, probablypresent by the late 1880sas evidencedby a marked expansion of range, and collected in 1892.S. marital'madisappeared from Southampton and nearby areas as the new form multiplied Marchant, 1967!. In 1968Hubbard recognizedthis form as a separatespecies and namedit S. anglica.This new specieshas proved to be an effectiveinvader of both formerly unvegetated rnudflats and of ,and, through a combinationof transplantingsfor marsh reclamationpurposes, vigorous clonal growth and natural dispersal,it now occupies 10,000hectares 5,000 acres!of the Britishcoast Spicher& Josselyn,1985; Thompson, 1991!. Another dimensionto this story is provided by Chevalier'ssuggestion 923; reported by Marchant, 1967! that S. maritimais itself not native to Great Britain, but was introduced there with shipping possibly in solid ballast! from Africa. S. anglicawas reported from Franceby 1894,where it spreadrapidly Marchant,1967!. To controlshoreline and create salt marshes,S. anglica has beenexported from Englandto many partsof the world, including Germany, Denmark, the Netherlands, China where it now occupies over 36,000hectares, almost entirely derived from 21 plants introduced in 1963!,Australia and New Zealand in 1930,where it was later declareda "noxiousweed"! Hedgpeth,1980; Spicher& Josselyn,1985; Chung, 1990; Callaway, 1990; Callaway k Josselyn,1992!. Chung 990! listed as additional reasonsfor planting S.artglica in Chinathe accretionof land for reclamation;the ameliorationof salinesoils; the production of greenmanure; the provision of pastureand fodder for sheep,goats, mules, donkeys, horses, pigs, cattle, dairy cows, buffalo, rabbits and geese;the production of feed for tilapia, grass carp and other farmed fish; the increasedproduction of nereid worms for export sale and of other invertebrates;the creation of biomass for fuel production; and the production of raw materialfor paper-making. In 1961or 1962the U. S. Department of Agriculture and Washington State Uruversity introducedwhat was then known as S. townseediiinto PugetSound, Washington.Ramets of theseplants were introducedinto SanFrancisco Bay at CreeksidePark Marsh,Marin County,as part of a marshrestoration project in 1977. Botanistsrealized these plants werein fact S. artglicawhen they floweredin 1983 Spicher & Josselyn,1985; Callaway, 1990!. Page 25 Introduced Species

In EnglandS,anglica has haxnpered shorebird movement and feeding and correlateswith a declinein dunlin Catidrisalpitta! numbers Goss-Custard& Moser,1990!, and has reduced macroinvertebrate densities Callaway, 1990!. S.angtica has proved to behighly invasive in manyparts of theworld e. g. southernGreat Britain, new Zealand and China!, and Thompson991! arguedthat S.anglica was a moresuccessful invader in Europethan the similar S. alternif1ora becauseof greater vigor and selective advantages conferred by allopolyploidy. However,in SanFrancisco Bay S. alterniflora is the aggressiveinvader while S. angelicahasnot spread from the marsh where it wasoriginally planted Spicher & Josselyn,1985!. Daehler pers. comm., 1994! suggests that the Bay is near the equatoriallimit of S.angelica's potential range, a suppositionsupported by S. anglica'sproduction of only 20% viable seeds in 1983and failure to flowerin 1984 Spicher& Josselyn,1985!.

Spartirta dertsiflora Brongniart [POACEAE!

DENSE-FLOWERED CORDGRASS Spartinadettsiflora isnative to Chileand was introduced to Humboldt Bay in thernid-nineteenth century, probably in theshingle ballast of lumberships returningfrom Chile a mechanismalso thought to beinvolved in thetransport of the shorehopperTransorchestia enigmatica to San Francisco Bay!. S. densiflorawas transplantedfrom Humboldt Bay to CorteMadera Marsh in 1976as part of a restorationproject at a timewhen it wasthought to be an ecotype of thenative S. foliosa. Spicher & Josselyn,1985; Callaway, 1990; Faber, pers. comm., 1993!. It is currentlyfound in saltmarshes at Creekside Park, Corte Madera Creek, Muzzi Marsh and GreenwoodCove, all in southeasternMarin County SpichertIc Josselyn, 1985!.

Spartit

SALTMEADOW CORDGRASS,SALT HAY Saltmeadowcordgrass is nativeto the easternUruted States from Maineto Texasand reported rarely from inland marshes in NewYork and Michigan. Meadowsof thiscordgrass were sometimes harvested for hayused in packingand bedding material Muencher,1944!. Munz 968! listedSpartina patens as "reportedfrom SouthamptonBay in a marsh,northwest of Benicia,Solano County, befall." Atwater et al. 979! referredto "R,E. Mall's report of salthay at SouthamptonBay" but couldnot find it thereor elsewherein theestuary. In 1985Spicher k Josselynagain found "an existing patch" of theplant in SouthamptonMarsh which "does not appear to have spread from its originallocation," and in 1993Josselyn etal. listed it fromSan Bruno Slough in the

Introduced Species Page 27

- 'vi Pr to ns Trocharttmina hadai Uchio This brackish water, benthic foraminifer is native to Japan.It has been found in sediznentcores collected in 1990-93frozn six stations in the South Bay and from threestations m the CentralBay near the Marin Countyshore. It has not beenfound in over 140sediznent samples collected in 1964-70and 1980-81from throughout the Bay D. Sloan,pers. comm., 1995; McGann, 1995; McGann k Sloan,1995!, suggesting that the introduction occurred in the 1980s. Furthermore,where it is presentT. hadaiappears to be abundantin the upper sections of cores, less abundant in lower sections, and absent at depth. For example, in a corefrozn the South Bay,T. hadaiaccounts for 52,2%%dof the benthic foraminifera in the top 2.5 cm, 8.8'/oat 8-10cm depth,0.7'/o at 18-20cm depth,and is absentfrom the next 33 sections examined down to 352 czn depth McGann, 1995!.In a core taken from RichardsonBay in the Central Bay,T. hadaiaccounts for 16/oof the foraminifera at 0-2 czn from the surface, 38 /o at 20-22 on, 26'%%dat 40-42 cm, 23'%%dat 60- 62 cm, 18'/aat 80-82cm, 2'/oat 100-102cm and less than 1'Yoat 120-122cm D. Sloan, pers.cornzn., 1995!. This pattern of depthdistribution is likely dueto bioturbationor other types of sedimentdisturbance znixing foraminifer testsfrom recently- deposited,near-surface sediments downward into deeperand earlier-deposited sediments.T. hadai'sdepth distribution may thus provide a meansof measuring thephysical and biological processes that mix sediznentsin differentparts of the Bay, which, aside frozntelling us somethingabout thoseprocesses, wiH be critical to efforts to use sedimentcores to decipherthe Bay'senvironznental history. Althoughforaminifera have sometimes been observed in sometypes of fouling WHOI,1952; ANC, pers. obs.!, transpacific transport in ship foulingseems unlikely for thisbenthic organism. Bottom sediments and presumablybenthic foraminifera as well are soznetimeschurned up by wind turbulence or ship activity and takenin alongwith waterinto ballasttanks; and foraminifera have been reportedfrom ballastwater, though rarely Carltonk GeHer,1993!. A benthic foraminifer could readily be transportedwith commercialshipments of oysters,but therehave beenno sigzuficantplantings of Japaneseoysters in SanFrancisco Bay sincethe 1930s Carlton, 1979a!.A possiblemechazuszn is transportin mud on anchorsor on anchorchains in chain lockers,as discussedby Schormannet al. 990!.

-a 't s Ancistrocontapelseneeri Chatton k Lwoff, 1926

SYNONYMs:Parachaenia myae This ciliate was describedas Parachaeniatnyae by Kofoid and Bush 936! fromthe pericardial region and excurrent siphons of theintroduced clam Mya arenariain SanFrancisco and Tomalesbays. Kozloff 946! subsequentlyreported it frozn another introduced clam, balthica, and from several native clams in Irrfroduced Species Page28

San Franciscoand Tornales bays, and synonymized it with the Atlantic ciliate Aneisfracomapelseneeri, described from Macomabalthica in Europe.

Ancisfrum cyctidioides Issel! Kozloff946! recordedthis Europeanciliate fram the introducedclam Mya arenaria in San Francisco Bay.

Boveria teredinidi Nelson, 1923

Pickard927! recordedthis Atlantic protozoanfram the gills ctenidia! of the introducedAtlantic shipworrnTeredo navalis in SanFrancisco Bay.

Sphenophyradosiniae Chatton k Lwoff, 1926

This European ciliate was reported by Kozloff 946! from the introduced clam Mya arenariaand the native clam Cryptomyacalifornica in San FranciscoBay.

Cofhurnia limnoriae Dans, 1927

This peritrich protozoan is found on the joints of the legs of the introduced wood-boringisopod Limnoria Mohr, 19S9! in SanFrancisco Bay, as discussed elsewhere,only non-nativespecies of this gribble occur!.It was reportedfrom San FranciscoBay by Kofoidk MiHer927, p. 330,as Cothurnia sp.!, although it may havebeen present since Limnoria's introduction about 1870.Although first describedfrom Europe,and later reportedfrom southernCalifornia Mohr, 1951!,its origins, like those of its host, are not known.

Lobochormprorates Mohr, LeVeque 8z Matsudo, 1963

This chonotrichprotozoan occurs on the bristles setae!of the gills pleopods! of the introducedwood-boring gribble Limnoria;as with other gribble associatesand the host speciesdiscussed here, the origin is not known. Lobachonaprorates was reportedby Kofoid 8zMiller 927, p. 330,as Spirochonasp.; seeMohr, 1966,p. S39! from SanFrancisco Bay, but mayhave been introduced about 1870 with the isopod itself. It is widely reported from harbors Carlton, 1979a!. In troducedSpecies Pagr 29

Mirofolliculinalimnoriae Dons, 1927

SYNONYMS:Fotliculina sp. Thisheterotrich protozoan lives on the back of the pleotelsonof the introducedgribble Limnoria. As with theother Limnoria associated ciliates, it is undoubtedlyintroduced, but its originsremain unknown. It wasreported from San FranciscoBay by Kofoid &cMiller 927, p. 330,as Fotlicutina sp.!,

INVERTEBRATES

PORtFERA Cliona sp.

BORING While the specieslevel of this yellow,shell-boring sponge remains unresolved,Ctiona is almost certainly representedby one or moreintroduced speciesin SanFrancisco Bay. Bay populations are likely to be referableto oneor more of the commonCliona found on oystersin Atlantic estuaries;these include Ctionacelafa Grant, 1826 and Ctiona lobataHancock, 1849 Carlton, 1979a,p. 218!. Japanesespecies or genomes!may also be present.Atlantic Cliona were introduced with Atlanticoysters. The first recordis that of Townsend893!, who observedthat in 1891large numbers of oystershells in theBay "were found honeycombed by the boring sponge."

Halichondria bowerbanki Burton, 1930

BOWERBANK'S HALICHONDRIA

SYNONYMS: Halichondria coatifa

This Atlantic sponge,known from both Europeand Atlantic America,was reportedfrom thePacific in SanFrancisco Bay in theearly 195Qs Carlton, 1979a!, and later from other sitesincluding Humboldt Bay S. Lamed, pers.comm., 1989! and CoosBay Hewitt,1993!. It waseither introduced with Atlanticoysters, with which it occurs pers. obs.!or as a fouling organism.In 1993-94we found Halichondriaon mostfloating docks and with otherfouling in the South,Central and San Fablo bays, though not on docks near the . introduce'd Species Page30

Haliclona laosanoffi Hartman, 1958

LOOSANOFF'S HALICLONA

SYNONYMS:Haliclona sp. B of Hartman, 1975 Haliclona ecbasis de Laubenfels, 1930 Wenewly follow andextend Van Soest 976! in designatingSan Francisco BayHatictona as the Atlanticnative Haliclona loosanoffi although the recognition of this speciesin the Baydoes not precludemore than one species being present!. 'Iousis a commontan, yellow, and orange sponge of Bayfouling communities.This is the samespecies referred to as Huticlovasp. B by Hartman975!, and is also the samespecies reported by Fell 970! as Haliclonaecbasis from BerkeleyYacht Harbor, St. FrancisYacht Harbor, RedwoodCity and CarmeLVan Soest 976! noted that Fell's970! descriptionof H. ecbasiswas very close to H. loosanofjin all characters, includingdetails of thelife cycle,but cameshort of designatingthe Baypopulation as the Atlantic speciessolely becauseit was in the Pacific Ocean Van Soestnot consideringthe possibility that it wasintroduced!. Haliclona, possibly including this species,have been reported from PugetSound, Coos Bay, Bodega Harbor, and severalbays in southernCalifornia Carlton,1979a, p. 216!. Haliclonaloosanoffi is a commonspecies of oyster communitieson the New Englandcoast pers. obs.!, and mayhave been introduced to the Baywith Atlantic oysters,although the earliestrecords are only from 1950 Hartrnan,pers. comm., 1977!.Its presencein foulingcommunities, however, means that it mayhave been introduced by ships as well. In 1993we foundHaliclona on mostfloating docks in the CentralBay and the seawardparts of Southand SanPablo bays. We did not find it in 1994and 1995.

Microciona protifera Ellis and Solander, 1786!

RED BEARD SPONGE

This large,common Atlantic spongeis known from Canadato South Carolina.It wasfirst found in SanFrancisco Bay in themid- to late-1940sby Woody Williams it wasnot notedby Light,1941!, who showed photographs to M. W. de Laubenfels who initially identifiedit as the nativeMicrocionu microjoanma; Hartman,pers. comm., 1977!. W. Hartman pers.corrun., 1977! found large colonies at RedwoodCity in 1950,and transplanted some of thesefor experimentalpurposes to BerkeleyYacht Harbor where it subsequentlybecaxne establishecL Its bright orange-redSinger-like colonies are unmistakable in the fouling communities aroundmuch of theBay. In 1993-95we observedit on several floating docks in the SouthBay, the eastern shore of theCentral Bay, and the southern part of SanPablo Bay. Onlytwo other populations are known on thePacific coast, from Willapa Bay Carlton,1979a, p. 215!and Humboldt Bay S.Lamed, pers, comm., 1989!. Introduced Species Page31

Microcionacould have been a late introduction with Atlantic oysters along with the crabRhithropanopeus harrisii and the whelk Busycotypuscanaliculatus whichwere first found in SanFrancisco Bay at aboutthis time,Microciona has been collectedfrom Atlantic oyster beds Wells,1961; Maurer & Watling,1973!. Since it is a commonfouling organism ANC & JTC,pers. obs.!, it couldalso have been introduced in ship fouling.

Prosuberites sp. This undescribedAmerican Atlantic sponge Hartrnan,pers. comm., 1977! wasfirst collected in theBay in 1953on Angel Island Carlton, 1979a, p. 217!.It may havebeen introduced to SanFrancisco Bay with Atlanticoysters or in shipfouling.

CNIDAlUA COKI.KNTK14%TA! Hy4xmm Numerousspecies ofhydroids have been introduced to the Bay since the GoldRush. We treat 13 species here. Campanutaria gelatinosa and Halocordyle dislicha =Pen@aria tiarella! may stiU be present in the Bay,but thereare no recent records, and we thus list them in Appendix 2.

Btackfordiavirginica Mayer, 1910 ThisSarrnatic hydroid, native to the Black and Caspian Seas, was first collectedin 1970in the NapaRiver and again in 1974in the PetalumaRiver. lt remainedmisidentified as a speciesof Phialidiu~!until 1993 Mills & Sommer, 1995!,when we collected medusae in bothrivers. In SanFrancisco Bay Blackfordia jellyfisheat copepods, nauplii, and barnacle nauplii Mills & Sommer, 1995!, Blackfordiamay have been introduced in ships'fouling or in ships'ballast water.The presence of widely scattered populations in theAtlantic Ocean ChesapeakeBay,Brazil, France, and Portugal! and in Indiaand China means that thesource of theBay's population is unknown,although it is possiblethat if other populationshave diverged genetically, candidate source regions could be identified. Theintroduction into theBay in the1980s-1990s of the clams Potamocorbula and Theora,the mitten crab Eriocheir,seven species of copepods,and other crustaceans, all fromAsia, might suggest a Chinese origin. Indeed, it is possiblethat the recent populationsof Blackfordia in the Bay represent a reintroduction of the species. 1ntrodueed Species Page 32

Cladonema uchidai Hirai, 1958

This Japanesehydroid was first collected in San FranciscoBay in 1979 Rees, 1982!,although the polyps and medusaethat have beenstudied to datehave originated from laboratory or home aquaria containing fouling organisms from San FranciscoBay. The polyps in the laboratory were smail .5 mm height! as were the medusae .5 mm height!, and little remains known of this hydrozoan in the Bay. Introduction with ship fouling or ballast water is possible, although earlier introduction with Japaneseoysters may have occurred if Cladonema'shabitat in Honshu includes oyster communities.

Clavtt multicornis Forskaal, 1775!

CLUB HYDROID

SYNONYMS:Clava IeptostylaAgassiz, 1862of northeastern Pacific authors; see Austin, 1984

Reesand Hand 975! noted that this northwestern Atlantic hydroid forms "large pink patches on pilings in estuaries."It was first collected in the Bay in 1895 Carlton, 1979b,p 229!, no doubt originating from ship introductions from the New England coast, where it is common. Fraser 937! describedits widespread distribution throughout the Bay as documented by Albatrosscollections in 1912-13.

Cordylophoracaspia Pallas, 1771!

FRESHWATER HYDROID

SYNONYMS:Cordytophora lacustris Allman, 1844

This brackish and freshwater Sarmatic hydroid, native to the Caspian and Black Searegions, was first found in the Bay in the SanJoaquin River at Antioch. Specimensdiscovered in 1950were considered to have been collected "20 to 40 years" previously Hand k Gwilliam, 1951!;we choosea dateof 1930as a first record, It was also collected at a similarly early but uncertain date from Lake Uruon in Seattle, and has now been reported from several sites between San Francisco Bay and VancouverIsland, British Columbia Carlton,1979a, p. 230!.It is sufficiently widespread around the world Hand k Gwiiliam, 1951!,a distribution perhaps achievedcenturies ago, as to make the origin of the Bay'spopulations unknown, It was likely introduced in ship fouling WHOI, 1952! or ballast water. Cordylophorais common in the Delta Hazel k Kelly, 1966! and on the concretesides of the Delta- Mendota water delivery canal Eng, 1979!,and has also been collected in San Francisco'sLake Merced Miller, 1958!. Page33 Introduced Species

Cary trtorpha sp. Thistiny estuarine, orange-tinted hydroid was collected from soft mud bottomson theeastern share of the Bayat PointRichmond 955-56! and in Oakland'sLake Merritt 967! Carlton,1979a!. It appearssimilar to the European Corymorphattutans M. Sars, 1835, but the species-level taxonomy remains unresolved C. Hand, pers. corrun., 1967!. No similarhydroid has been reported fromelsewhere on the Pacificcoast. In LakeMerritt it occursin samplesotherwise composedentirely of introduced species. This facies, the absence ofany similar Pacifictaxon, and its similarity to anAtlantic species, leads us to consider it to be introduced,either via oystershipments, ship foulingor ballastwater.

Garveiafrartciscarta Torrey, 1902!

SYNONYMS:Bittteria frartciscarta Thishydroid, often considered under the Bittteria, is common in the Bayand reported to be one of theprimary food sources of the introduced Asian isoppdSynidotea laevidorsalis Carlton, 1979a!. Possibly native to northernIndian Oceanestuaries, it has been introduced in shipfouling and, in lateryears, possibly by ballastwater, to many harbors and ports around the world. It hasbeen reported from westernAfrica, northwestern Europe, eastern North America, the Gulf of Mexico and Australia Carlton, 1979a,p. 225!. Garveiawas first collectedby Torreyin 1901 Torrey, 1902; Vervoort, 1964! in SanFrancisco Bay, its only confirmed location on the Pacific coast. In 1993-95we foundit in densemasses under floating docks at somesites in SanPablo Bay, coated with the introducedbryozoan Cortopettm tertuissimum and crawlingwith Syrtidotea.We consider it a shipfouling introduction.

Gottofhyraeaclarki Marktanner-Turneretscher,1895! Thiswell-known North Atlanticfouling hydroid was first collectedm San FranciscoBay in "OaklandCreek" in 1895and again at various stations around the Bayby the Atbatross in 1912 both are unpublished NMNH records!. Graham h Gay 945!recorded it again in fromthe based upon their 1940-42 studies.Rees k Hand975! notethat it is "oftenvery common on harborfloats" in centralCalifornia. In 1995we collected it fromfloats at theGrand Street Oakland Estuary!,Emeryville and Coyote Point marinas in SanFrancisco Bay, and from IsthmusSlough in Coos Bay. Since Gortothyraea canbe clearly distinguished from Obeliaonly if gonozoidsare present K. Kozloff, pers. comm., 1995!, some Pacific coastrecords of Obeliamay actually refer to Gonofhyraea.Gortofhyraea species have beenreported from ship fouling WHOI, 1952!, and it waslikely introduced either in fouling or with oysters. Jntroduced Species Page34

Maeotias inexspectata Ostroumoff, 1896 AnotherBlack Sea native, Maeofias was first foundin the turningbasin of thePetaluma River in 1992,and became sufficiently abundant by thesuxnmer of 1993to attract public attention Mills & Sommer, 1995!. Outside of the Black Sea it was previously known froxn two regions on the Atlantic American coast ChesapeakeBay and South Carolina!and France Mills & Soxnmer,1995!;the source of the Baypopulations is as yet unknown.In the PetalumaRiver these jellyfish eat primarily barnacle nauplii, copepods,zoea larvae of the introduced Atlantic crab Rhithropanopeusharrisii, tanaids and other invertebrates, and in thelaboratory tolerated salinities up to 13 ppt Mills & Sommer, 1995!, Mills & Sommer995! concludedthat the Maeotiaspopulation in the PetalumaRiver appears to havebeen introduced as polypsrather than xnedusae, sincethe medusae population in theRiver is entirelymale and therefore incapable of reproduction.A polypisolated froxn the Maeolias population, however, readily reproducedasexually in the laboratory,creatmg numerous new polyps which then producedmale medusae. Both polyps bothunattached and on floatingdebris! and medusaeof hydroidsare known froxn ballast water, making this or ship fouling the probable means of introduction.

Obelia?dichotoma Linnaeus, 1758! and Obelia?bidentataClark, 1876 Weconsider these two speciesof Obeiia,described from Europeand New Englandrespectively, asintroduced, and provisionally use the naxnes adopted by Cornelius975!. Obeiiadichotoma was collected in 1894and later years identified asO. commissuralis!and in 1899and later years identifiedas O. lorrgissima!froxn theBay unpublishedNMNH records!. Obelia biderxfata was collected in theBay in 1912 identified as O. bicuspidata! Fraser, 1925, and unpublishedNMNH records!. Obeiiaspp. occur throughout the Bay's fouling communities, although in relatively low numbers. Kofoid 915! early on referred to the "contamination" of Pacific coast harbors by ship-introduced"tubularian and campanularian hydroids." Obelia species have frequentlybeen reported froxn ship fouling WHOI,1952!, and thereis little doubt thatObelia from around the world were a commonelexnent of ships'fouling communitiesbrought to the Bayfrom the GoldRush era on. Obeliamay have commencedits world journeyson shipbottoms in the 13thcentury, making identificationof original sourceregions difficult. Obeliahas no doubt been introducedinto the Baycontinuously over the years in ship fouling,with commercialoysters both from theAtlantic whereit occursin oysterbeds; Wells, 1961;Maurer & Watling,1973! and from Japan, and in recenttixnes in ships'ballast water, primarily as hydromedusae. The native nudibranchDoto kya and the introducednudibranchs Eubranchusmisakexxsis andTeneBia edspersa apparently feed upon Obelia in San FranciscoBay Behrens,1971, 1991; Carlton, 1979a. Jaeckle, 1983!. introducedSpecies Page 35

Sarsiatubulosa M. Sars,l835! SYNONYMS;gyncoryne mirabilis >gas or ne rosariaAgassiz, 18 B y ~ gory' ros«y sc e o ~ Atl ti hydroidscollec ed y g 6 e late 1850s.He coHected~ y CQ lurnbi a 1860 Carlton. 19 i P' matters P f th d ys of woodenships;" theprobable means of dispel o d d f orn Alaska to southern Califo more th~ one sP ~es ~ »

Tubularia crocea Agassiz, 1862! SYNONYMS:Parypha microcephala Agassiz, 1S65 Tubularia elegansClark, 1876 Petersen990! proposesthat Tubularia croceabe transferredto the genus Zctopleura. This commonAtlantic fouling hydroid, known from Newfoundlandto Florida and the Gulf of Mexico and frequently reported from ships' fouling communities WHOI, 1952!,was introduced by Gold Rush ships to the Bay. It was first collected in 1859by Alexander Agassiz who mistakenly describedit as a new species,Parypha microcephala; Carlton, 1979a, p. 238!"attached to floatinglogs round the wharves of San Francisco."It has since been collected from the Gulf of Alaska to Tubularia croceahas been frequently munities, although somelater introductions may have oc ~ ith AQ oysters.with whichit occurson the Atlanticcoast ~eg ]96/ ~ ' " ' ~a rickettsi Sa+rae0Iis e~osimm Tenelliaadsp~rsa repo rtedly feed upon Tubular+ m S F ' o B C 1979a;Behrens, 1984, 1991!,

Mggh

MOON JELLY Introduced Speer'es Page36

SYNONYMS: Aurelia labiata

Greenberg 995! reports that a sometimesdense population of Aurelia auriga in Foster City on the San Mateo side of the South Bay!, present since at least around 1989,is geneticallysimilar basedon allozymecomparisons! to Aurelia from Tokyo Bay,Japan and unlike Aurelia from MontereyBay and VancouverIsland. Differencesin the structureof the radialcanal further distinguish the Japanese and SanFrancisco Bay from the northeasternPacific stocks. Aurelia has been seasonally abundantin recentyears in FosterCity Lagoonand RedwoodCreek, both on the southwesternshore of SanFrancisco Bay g. Thompson,pers. comm.!. We know of no earlier reportsof Aurelia m SouthBay ,although there are recordsof swarmsin TomalesBay Rickettset al., 1985;T. Gosliner,pers. comm.,1995! of this specieswhich is normally found offshorein centralCalifornia latitudes Rickettset al., 1985;E. Kozloff, pers. comm,, 1995!. The SanFrancisco Bay population mayhave been introduced as larvae knownas ephyrae! in ballastwater, since we have found live scyphozoanephyrae in theballast water of freightersarriving at CoosBay, Oregon from Japan. Ricketts et al. 985! describeAurelia polyps as "extraordinarily tough and resistant,"so transportacross the Pacificas ship fouling would alsobe possible. As Aurelia aurita was first described from North Atlantic waters, and since thereis evidenceof bothgenetic and morphological differentiation, the species-level taxonomy of the group may require revision.

haihazaa Diadurnene ?cincta Stephenson, 1925

ORANGE ANEMONE

Betweenthe mid-1950s Hand, 1956!and early 1970swhen it wasfirst collected no exactdate is availableas of this writing!,a fourthspecies of Diaduntenewas introducedinto SanFrancisco Bay Carlton,1979a!. Its morphologyand distribution in the Bay were extensivelystudied by T. Blanchard,whose work and taxonomic conclusionsremain unpublished, but who felt that there was a "strongcase for conspecificity"with the European primarily British! Diadumenecincta. We tentativelyuse that name for thisanemone, to which it is morphologicallyvery similar. Diadumenecincta occurs in Britainboth on openmarine shores and in estuaries, tidal creeks,and harbors Manuel, 1981!,Blanchard also found the same speciesin Humboldt Bay T. Blanchard,pers. comm., 1988!. Blanchard pers. comm., 1988! has provided the following information about this anemonein SanFrancisco Bay. Diadumene?cinctahas a column diameter of about15-20 mm anda columnheight of up to five or moretimes the width. The mostcommon variety of Diadumene?cincfaondock floats is solidorange, but pmk formsalso occur, most commonly sublittorally on pilingsand in themid to low intertidalzone in protectedlocations. Specimens also occur sublittorally on shells Introduced Species Page 37 partially buried in sediment.White markingson the oral disk are commonon the pink forms,but have not beenobserved on orangespecimens. The anemone commonlyforms clonal aggregationsof up to 200individuals in fouling, a character typicalof the EuropeanD. cincta Manuel, 1981!; it mayalso occur singly. As this anemoneis not described in Hand 975! nor in other guides to Pacific coast , it maybe mistakenfor Diadumeneteucotena or stripelessHaliplanella lineafa. We tentativelyassign an Atlantic origin to this species.It was probably introduced either in ship fouling or ballast water.

Diadumenefranciscana Hand, 1956

SAN FRANCISCO ANEMONE Thisusually white-striped introduced anemone of unknownorigin hasbeen reportedfrom San Francisco Bay before1941!, Morro Bay 973! Carlton,1979a, p. 250!and MissionBay 977-78! Dygert,1981!, and we collectedit in TomalesBay in 1995 identified by C. Hand!.Carlton 979a! suggested that it mayoriginate from the southern Pacific or Indian Oceans,rather than from the Atlantic, where the anemonefauna is better known. As the anemone fauna of Japan is also relatively well studied,oyster transplantation from either the Atlantic or fromJapan is not the likely mechanismof mtroduction.As it is a commonfloat andpiling fouling organismlocally in SanFrancisco Bay, it mayhave been introduced as hull fouling, or elsein ballastwater. Diadumenefranciscana can be very commonin the warm marginsof the Baywhere other species, such as thetubeworm Ficopomatus enigmaticusand the barnacleBalanIts amphitriteamphitrite of known warm-water origin are also common.Its presencein warm-waterthermal effluentsin Morro Bay to whereit waslikely introducedfrom SanFrancisco Bay! is alsosuggestive of a warm temperate or subtropical origin. The first record of this anemoneis that of Light 941, as a "double-striped anemone"from !,whose records were basedupon his field observationsmade in the Bay since the 1920s.

Diadumene leacolena Verrill, 1866!

WHITE ANEMONE This Atlantic anemone,occurring from at leastCape to South Carolina, was first reportedfrom the OaklandEstuary by Sander936!, althoughit may have beenpresent in theBay since the 19thcentury. Hand 956! describedit in detail from the Bay.It is commonto abundantalong the Bay margin,in foubng communities,under rocks,and on oystershells, and may havebeen introduced with oystershipments it is xmordedfrom Atlantic coast oyster beds; Wells, 1961!, as shipfouling or in baUastwater. It hasalso been reported from southern California bays and from CoosBay, Oregon Carlton, 1979a,p. 248!. Introduced Species Page38

Diadumene lineata VerriH, 1873!

ORANGE-STRIPED GREEN ANEMONE

SYNONYMS:Haliplanella lineafa Haliplanella luciae VerriH, 1898! Diadu mene luciae Aipfasiornorpha luciae

This abundant, often orange-striped anemone,known in most hterature as Haliplanellaluciae VerriH, 1898!,was first collectedin SanFrancisco Bay in 1906 Davis, 1919!,and has since been collected from bays and harbors from Newport Bay to British Columbia Carlton, 1979a,p. 253!. It is now one of the most common anemonesalong the marginsof SanFrancisco Bay, occurring in habitats ranging from fouling communities to bits of shell on open mudflats to channels.A native of Japan,it hasbeen widely dispersedaround the world by both shippingand by the movement of commercialoysters, either or both af which mechanisms could have brought it to the Bay. That it may have arrived with the large volumes of Atlantic oysters brought to the Bay in the 1890sis suggestedby its late appearancein New England892; Verrill, 1898!and its presencein Atlantic coastoyster beds WeHs,1961; Maurer k Watling, 1973!,and it may thus be another example of the many specieswhose arrival in one region in this case San Francisco Bay! was contmgentupon its introduction to anotherregion New England! thus interfacing with an ongoing transport vector and dispersal corridor the commercial oyster industry!. Haliplaneilahas the ability, perhapsunique ainong the anemones,to encyst, leaving behind upon excystment a tough capsule Kiener, 1972!. This remarkable characteristichas likely conferredupon Haliphnellaan unusual ability to survive ]ong-distance transport under severe conditions Carlton, 1979a!.The introduced percafeeds upon Hali planella in the Bay McDonald, 1975; Carlton, 1979a!.

ANNxuDA

Of all the common macroinvertebrates in San Francisco Bay, the oligochaetes are perhaps the poorest known relative to the comparative diversity of native versus introduced species.We recognize here eight introduced oligochaetes and list four others as cryptogenic Chapter 4!, although the latter are frequently abundant and embedded in communities otherwise composedof non-native species.Annelid taxonomy is widely recognized as a difficult and complex field; and although we know relatively little about the Bay's ,we know even less about its oligochaetes Page39 Introduced Species Eachof thefollowing species ofoligochaetes could have been present in San FranciscoBayfor many decades, if not since the 19th century, before they were first collectedin the 1950s and 1960s. We thus regard the dates of first collection ofmost of thefollowing species asartifacts ofthe collecting effort. The decades- tocentury- longuncertainty inthe actual dates ofintroduction makes it hard to determine transportmechanisms. Wegenerally consider ships' solid baHast andwater baHast, shipmentsofcommercial oysters, andshipments ofaquatic plants tobe possible vectors.

Branchiurasoverbyi Beddard, 1892 [TUBIFICIDAK] Thisoligochaete, native to tropicaland subtropical Asia , Burma!,Java, China, Japan!, was first collected in1892 from the mud of the Victoria regiatank in the garden ofthe Royal Botanic Society inRegent's Park, London. Over thenext 30 years it was collected from other warm-water tanks in botanic gardens at Hamburg,Dubijn, Kew and Oxford. Bythe late 1950s it had been found "in the wild" in theRhone River and elsewhere in southern France, in theThames River below Readinginwater warmed byeffluent from a powerstation, and in unheated waters in theKennet and Avon Canal and in theBradford River Avon in England Mann, 1958!.It has also been reported from north and west Africa Brinkhurst, 1965!. It wasfirst collected in North America in centralOhio in 1930 Spencer, 1932!, andspread tothe Great Lakes by 1951 Mills et al., 1993! and to a totalofeighteen statesby1966 Brinkhurst, 1965;Cole, 1966!. InCalifornia it was coHected fromthe SanJoaquin River in 1950,from the Tuolomne River near Modesto in 1952 Brinkhurst,1965!, and from the Delta in 1963 specimen atCASIZ!. The CaHfornia DepartmentofWater Resources hascollected it throughout most of theDelta since samplingstarted in 1977 from the western Delta upstream tothe ,Courtland on the Sacramento River, and Stockton on the !, atdensities ofup to 823/m2 Markmann, 1986; DWR, 1995!. We found no other recordsof 8ranchiuraonthe Pacific coast. Branchiura could have been transported to Californiain ships'solid or waterbaHast or onornamental aquatic plants.

Limnodrilus mortofhecus Cook, 1974![TUBIFICIDAK] Althoughfirst described from Bahia de San Quintin, Baja California based uponspecimens coHected in1960 Cook, 1974!, Erseus 982! demonstrated thatthis marineand estuarine species is widely distributed from the mid-Atlantic coast to the Gulfof Mexico,and was only found in threestations in BritishColumbia, southern California,and Bahia de San Quintin on thePacific coast. Nichols 8z Thompson 985!record it from their south San Francisco Bay stations, where they treatedit as cryptogenic. It appears, however, tobe an Atlantic species introduced to westcoast estuaries. It could have arrived in ships'solid or waterballast or in shipmentsof commercialoysters. IntroducedSpecies Page 40

Paranaisfrici Hrabe, 1941[NAIDIDAE]

Brinkhurst & Cook 980! regard the fresh and brackish water P.Pici as a European Sarmatic! species introduced into North America. Brinkhurst & Simmons968! found it to be oneof two abundantoligochaetes in SuisunBay in 1961-62. It was collected in the eastern Delta Mokelumne River! in 1977-79, and in the westernand centralDelta in 1980-95,at concentrationsup to l>96/m2. Brinkhurst & Coates 985! also report it horn Newport Bay, California and Fraser River, British Columbia, and note that it has been further reported from Africa and South America. It could have arrived in California in ships' solid or water ballast or on ornamental aquatic plants.

Potamothrix bavaricus Qschman, 1913! [TUBIFICIDAE]

This freshwater Eurasian specieswas regarded as "possibly" introduced to eastern North America by Brinkhurst 965!, who further recorded a population collected by R. Whitsel, no date given! from Coyote Creek, in Santa Clara County. We tentatively regard it as introduced, if the identification is correct. It has been reported from the central and western Delta since 1991,at concentrationsup to 415/m2 DWR, 1995!. It could have arrived in California in ships' solid or water ballast or on ornamental aquatic plants.

Tubificoides apectinatus Brinkhurst, 1965! ITUBIFICIDAE]

This common North Atlantic coast marine oligochaete Brinkhurst, 1981, 1985! was found to be abundant in South SanFrancisco Bay sediments in 1961-62 collections Brinkhurst 8x Simmons, 1968, as Peloscolexapectinatus!. It could have arrived in ships' solid or water ballast or in shipments of commercial oysters.

Tubificoides brownae Brinkhurst k Baker, 1979 [TUBIFICIDAE]

S~o~s: Peloscolexgabriellae of authors

This North Atlantic marine oligochaete described from Delaware, and known from other Atlantic coastalsites as well as Europe! was treated by Brinkhurst k Simmons 968! as Peloscolexgabriellae in part!, from the South Bay Brmkhurst, 1986!.I't is also known from CoosBay, Oregon Brinkhurst,1986!. Nichols 8z Thompson985! reportedit as a cryptogenicmember of the SouthSan Francisco Bay rnudflat community. We regard it is as introduced basedupon its broad Atlantic distribution and its apparently restricted distribution m the Pacific Ocean.It could have arrived in California in ships' solid or water ballast or in shipments of commercial oysters. Irr trod~ced Species Page41

Brinkhurst & Simmons968! examinedspecimens collected in 1961-62. Brinkhurst965!, underthe name Peloscolex gabriellae, records material from 1957 collectedby M.Jones! from Point Richmond, but it is notclear if thesespecimens arereferable to T. brownaeor to T. wasselli below!. The California Department of WaterResources reports T. brownae collected in smallnumbers from and Pt. Finole since 1987 DWR, 1995!.

Tubipcoideswasselli Brinkhurst & Baker,1979 [TUBIFICIDAK] ThisAtlantic marine tubificid is knownfrom Delawareto the Gulf of Mexico Brinkhurst,1986!. San Francisco Bay populations collected in 1961-62 and identified byBrinkhurst & Simmons 96S! as a paplllateform of Peloscolexgabrielhre arenow consideredto be this species Brinkhurst, 1986!. It is otherwiseknown from Victoria, BritishColumbia Brinkhurst, 19S6!. It couldhave arrived in Californiain ships' solid or waterballast or in shipmentsof comxnercialoysters.

Vart'chaetadrilusangustipenis Brinkhurst & Cook,1966! [TUBIFICIDAK]

SYNONYMS:Lirnnodrilus angustipenis Thiseastern United States species Brinkhurst, 1971; Strayer, 1990; Krseus et al.,1990! occurs widely in theSacramento-San Joaquin Delta in freshwatermuddy sediments.It wascollected by the CaliforniaDepartment of WaterResources at least asearly as 1982 in stationsnear the western end of ShermanIsland Hymanson et al. 994! reportedthat it wasone of thenumerically dominant species at thesesites from1982-86, concluding that it andLirnnodrilus hogneisteri here treated as cryptogenic!"are among the few native benthic organisms that have maintained their numerical dominance and broad distribution..." V. angustipeniscould have arrived on the Pacificcoast in ballastwater or on ornamental aquatic plants.

5@r~a~ Boccardiellaligerica Ferronnikre,1898! [SPIONIDAB]

SYNONYMS;Boccardia ligerica Ferronniere, 1898 Boccardia nr. ancata Polydora uncata Polydora redeki Horst %Msspionid worm is nativeto thebrackish waters and mudflats of France, Hollandand Germany. A singlespecimen identified as Boccurdiella ligerica was collectedfrom Newport Bay in 1935 Kudenov, 1983!. B. ligerica was collected from tntroduced Species Page42

San FranciscoBay in the San Pablo Channel by 1954 and from the Delta-Mendota Canal, in , in 1973 Light, 1977;Carlton, 1979a,p. 30S!.It was also collected from freshwaterin the New River and the Alamo River in Imperial County in southeasternCalifornia in 1979,and from a canalin Mar Chiquita, Argentina with the Australian serpulid worm Ficopomatusertigmaticus Kudenov, 1983!. Boccardiellaligerica may have been introduced with ships' ballast water, perhaps during World War II or the Korean War. Spionid larvae are among the most abundant and frequently encountered groups of organisms in ballast water Carlton k Geller, 1993!. B. tigericawas one of the most common benthic organisms collected by CDFG near Martinez in 1975-1981,and was found upstream as far as Collinsville in the western Delta Markman, 1986!.In 1976,a dry year, Siegfried et al. 980! found B. ligerica to be a dominant species at their upstream stations near Collinsville in the late summer and fall, with peak densities of around 20,000individuals/m2, and Markman 986! similarly reported an increase in B. ligericaupstream in the dry year of 1981.Light 978, p. 201! summarizing recent studies showed 8. 1igerica collected only from the ends of the Bay: at the southern end of the South Bay and from Martinez to the in the northern Bay.

Ficopomatusenigmaticus Fauvel, 1923! [SERPULTDAE]

AUSTRALIAN TUBEWORM

SYNONYMS:MercieretIa enigrnatica

Ficopomatusenigmaticus is an Australian worm that builds and lives in a white, calcareoustube, the tubes forming large agglomerate masseswhen the worm is abundant. Reported from ships' hulls WHOI, 1952! and probably transported as hull fouling, it has becomeestablished in many parts of the world including the Black, Caspian and Mediterranean seas,northern Europe, Uruguay, Argentina, Hawaii, Japan and the Gulf of Mexico. It was first reported in San FranciscoBay from Lake Merritt, a tidal lagoon on the East Bay shore, in a 1921article in the Oakland Tribune headlined "Coral Reefs Spreading in Lake Merritt." The "reefs" had been first noticed by park officials about a year earlier. It was also in 1921that F. enigmaticuswas discovered and described in France, and discovered at the London docks Carlton, 1979a!. F. enigmaticus apparently requires water temperatures of at least 18'C to breed Obenat k Pezzani, 1994!, and in Europe it frequently lives in water heated by the cooling water effluent from power plants Vaas; 1978!. In the Netherlands its colonies have interfered with operations Vaas; 1978!. F. enigmaticushas beencollected from many sitesin the South,Central and San Pablo bays, sometimes in densemasses, especially from enclosedlagoons or protected waters. Thesesites include Aquatic Park Lagoon in Berkeley first appeared between 1942and 1946,and still abundant!, Alameda Lagoons abundant in 1971, scarcein the 1990s!,Berkeley Yacht Harbor 969!, San Rafael and Corte Madera Page43 Introduced Species Creek970!, Palo Alto Yacht Harbor and China Camp 974!, Foste Ci y Lgoons andBelvedere I.agoons before 1979!, and the Turning Bsin abundantin 1993' see Carlton, 1979a, p,331., for references onthe other records!. It is lessabundant now in LakeMerritt than it wasin the1920s and the 1960s-70s. Newman's963! report of a serpulidworm "comparable toMerciere/ta enigmatica"inthe seawater system ofa navalvessel docked inSan Francisco Bay suggeststhat it mayhave been introduced more than once.

Heteromastusfilifonnis Claparede, 1864! [CAPITELUDAE] Heteromastusfiliforrnis isnative to the Atlantic coast ofthe United States fromNew England tothe Gulf of Mexico, and has also been reported from Greenland,Sweden, theMediterranean, Morocco, South Africa, the Persian Gulf, NewZealand, Japan, and the Bering and Chukchi Seas. The wide temperature range coveredbythese locations suggests thatmore than one species maybe involved. In CaliforniaHeterornasfus wascollected from San Francisco Bay in 1936,from Morro Bayin1960, possibly fromsouthern California by1961, and from Bolinas Lagoon by 1969.It was collected from Vancouver Island in 1962,from Coos Bay, Oregon in 1970 pers.obs.!, and from Grays Harbor, Washington by1977 Carlton, 1979a, p.322!. Aswith other polychaetes firstcollected onthe Padfic Coast inthe 1930s by QlgaHartman including Polydora ligniand Sfrebfospio benedicti inSan Francisco Bay!,Heterornastus fitiformis may have been. present but undetected formany decadesdue to the lack of earlier investigations ofintertidal polychaetes onthis coast.Thus this mud-dwelling capitellid worm may have been introduced toSan FranciscoBayin the late nineteenth orearly twentieth century with Atlantic oysters, withwhich it occurs;Wells, 1961!, ormay have been an early ballast water introduction.Heteromastusfiliformis is commonlycollected from the far South Bay to the westernhalf of Suisun Bay at concentrations of 10to 4000 per square meter, and has beencollected upstream toPittsburg Hopkins, 1986; Markmann, 1986!. It is one of themost common benthic organisms in the shallows of SanPablo Bay and the channelsof the SouthBay Nichols& Thompson,1985a!.

Manayunkr'aspeciosa Leidy, 1858 [SABBLLIDAEJ SYNONYMS;Manayunkia eriensis Krecker, 1939! Manayunkiaspeciosa is a freshwaterpolychaete native to eastern North Americafrom the westernmost Great Lakes, New York and Lake Champlain in Vermontsouth to theSavannah River in SouthCarolina Klemm, 1985!. It was collectedfrom two small, shallow lakes in northern Alaska in1961 and 1964, and fromSevenmile Canal in Klarnath County, Oregon in 1964 Hazel, 1966; Holmquist, 1967;Croskery, 1978!. It was first collected inCalifornia from the Mokelumne River nearNew Hope Landing inthe eastern Delta in 1963 Hazel, 1966! Hartrnan's 969! Introduced Species Pttge 44

report of this speciesfrom SanPablo and Suisunbays appears to be basedon a misreading of earlier reports. Thistube-dwelling, colonial worm has neither a restingstage nor a planktonicor swimmingstage that mightaid dispersalor transportin water youngworms mature within the parentaltube and emerge as small, crawling adults to build tubesnearby Holmquist, 1967; Croskery, 1978!. However, transport in detrituscarried in watermay be possible.Hazel 966! suggestedthat M. speciosa arrived in the Delta in the water in which freshwatergamefish from the eastern UnitedStates were transported. Hazel 966!, citingSmith 896!, notedas pertinent the fact that white catfish Ictalurtts now Ameittrus! catus introduced to the Delta in 1874were taken from the SchuylkillRiver, Pennsylvania, the type localityfor M. speciosa.However, although Smith 896! describesthese as "white catfish or Schuylkillcatfish," he clearlystates that the fish transportedto Californiawere taken from the RaritanRiver, New Jersey.Thus "Schuylkill" appears to bepart of a commonname for thesefish, ratherthan the site from whichthey werecollected Although most or all of the introduced to California from the northeasternUnited Statesappear to havebeen planted in the late nineteenthor early twentieth century Table 1! and Manayunkiawas not discoveredin California until 1963,it is possiblethat this smallpolychaete was present and overlookedfor a longtime Holmquist,1967; Mackie k Qadri,1971!. Alternatively, it may have been transported in detritus floating in freshwater ballast. Martayttnkiuis the fourthmost numerous benthic invertebrate collected by the California Departmentof Water Resourcesin the Delta,with densitiesin the interiorof theDelta of 2,000to 50,000individuals/m2. It apparentlyrequires fresh waterand silty substrates,and is foundin theeastern portions of theDelta downstreamto Frank'sTract and Rio Vista, with questionablerecords from * few stationsfurther downstream Markmann, 1986; Herbold k Moyle,1989; Hymanson et al., 1994!.

Marenzelleria viridis Verrill, 1873!tSPIONIDAE]

SYNONYMS:Scolecolepis viridis Scolecolepis ten@is Scolecolepides vi ri dis

Marenzelleria viridis is native to the northwestern Atlantic and was collected in Germanyin 1983,probably havingbeen introduced via ballast water Essink8c Kleef,1993!. It spreadthough western and northern Europe and into theBaltic Sea, where it is now extremely abundant. It was first collected on the Pacific coast in Nov. 1991 at Collinsville on the SacramentoRiver, at which station it has been found most consistentlyand abundantlyat up to 1700worms/m2. It has sincebeen collectedfrom Frank's Tract and the Old Riverin theDelta downstream to Grizzly Bayin 1992,in SanFablo Bay in 1995,and in thefar SouthBay M.Kellogg, pers. comm,1995; W. Fields,pers. comm., 1995; DWR, 1995!. It probablyarrived in ballast water. Page45 Introduced Species

Marphysasanguinea Montagu, 1815! tEUNICIDAE] Marphysasattgttinea isregarded asa singlecosmopolitan species,but likely consistsofseveral difficult-to-distinguish butdistinct taxa. It isreported from Europe from Great Britain tothe Mediterranean!, thewestern Atlantic Massachusettstothe West Indies, the Gulf of Mexico, Bermuda andthe Bahamas!, Japan,China, and from Australasia tothe Red Sea and Africa, Inthe eastern Pacific it hasbeen known from San Francisco Bay since 1969, and from various sites betweenLosAngeles andPanazna Carlton, 1979a, p.302!. The San Francisco Bay populationmayhave been introduced fromthe Atlantic with shipments ofoysters, withwhich it occurson the Atlantic coast Wells, 1961!, or it mayhave been introducedHopkins in ballast969! water.reported M.sattgttinea ascommon atconcentrations of10-200 persquare meter, but found only in the South Bay south ofHunters Point, and most commonlyin the channels.

Nereissttccirtea Frey & Leuckart,1847! [NEREIDAEj

PILE WORM

SYNONYMS: Nean thes sttccirtea Nereis saltorti Hartman, 1936 Nereis limbata Webster, 1879 Thiseuryhaline "pile worm" lives in a varietyofhabitats; under rocks, in mudand sand, in oysterbeds and in foulingcommunities. It isreported from locationsaround the world, including the eastern Atlantic and the Mediterranean; thewestern Atlantic from the Gulf of St.Lawrence to theWest Indies, Gulf of Mexicoand South America; West Africa and South Africa; and the tropical eastern Pacificfrom the Gulf of Californiato Colombia Carlton, 1979a, p. 295!.These reports mayinvolve a singlespecies transported synanthropically aboutthe globe, or multiple, closely-relatedspecies. In Californiait hasbeen collected from San Francisco Bay earliestrecords from1896!, the Salton Sea from 1935!, 941!, several southern Californiabays from 1952!, and in Oregonfrom Netarts Bay 976! Carlton,1979a! andCoos Bay 986; pers. obs.!. The San Francisco Bay population probably originatedinthe western North Atlantic and arrived inshipments ofAtlantic oysters with which it occurs onthe Atlantic coast; Wells, 1961; Maurer k Watling, 1973!or in shipfouling. It may have been independently introduced tosouthern Californiabays in baUast water or as fouling, or secondarily introduced from San FranciscoBay by coastalshipping. Nereissttccinea is commonin SanFrancisco Bay in watersof lessthan two metersdepth, generally atconcentrations of 10-400 individuals/m>. It has mainly beencollected in the northern Bay from to Antioch,and in thefar SouthBay below the Durnbarton Bridge Hopkins, 1986!. It is one of thedominant Introduced Species Page 46 benthicorganisms in SuisunBay Nichols k Thompson,1985a!. As discussedby Oglesby 965!, the native worm Nereis vexillasaoccupies more marine waters in the Central Bay and the native Nereis limnicola occupies fresher waters in the Delta. Nereissuccirtea may thus have squeezedin betweentwo existing pile worm populations,with eachpopulation restrictedby a combinationof physiological limitations and competition with its neighbors. Recher 966! noted Nereis succirtea in the diet of shorebirds in the South Bay, and Oglesby965b! reportedon infectionby the trematodeparasite Parvatrerrta borealisalong the East Bay shore. Carlton 979a! summarizes other research on the worm's physiology and ecology.

Polydoraligrti Webster, 1879 [SPIONIDAE]

MUD WORM

SYNONYMS:Polydora amarincola Hartman, 1936

Polydora ligrti is native to the northern Atlantic where it is found in mudflats,fouling including ship fouling; Hartman,1961! and oysterbeds, sometimesforming thick mud bedsthat causeextensive oyster mortalities.In the Pacific it was first collected in Ladysmith Harbor, British Columbia in 1932 " on [oyster]cultch sacks"!,in SanFrancisco Bay in 1933 redescribedas Polydora amarincola!,and in False Bay on San Juan Island, Washington in 1937.It has since beenreported from otherbays and harbors in BritishColumbia, Washington and Oregon,and from DrakesEstero, Bolinas Lagoon, Elkhorn Slough, Morro Bay, Mugu Lagoon,Santa Monica Bay,/LongBeach Harbors, Alamitos Bay, Anaheim Bay, SantaCatalina Island, Mission Bay and the SaltonSea in California seeCarlton, 1979a, p. 306,for references!.There are a fewrecords, questioned by Carlton 979a!, from Mexico, As with Heteromastttsfiliformis, Polydoraligrti could have been transported to the Pacific coast with Atlantic oysters decadesearlier and overlooked, or transportedin ballast water larvaeof Polydoraspecies have been found to survive transportin ballasttanks; Carlton, 1985,p. 345!,or possiblyin ship fouling. Considerablemovement between embayments along the coast may have occurred with shellfishtransplants or coastalshipping. In SanFrancisco Bay it hasbeen collectedfrom the far SouthBay to CarquinezStrait Light, 1977,1978!, and is oneof the more commonbenthic organisms in the shallowsof SanPablo Bay and the channelsof the SouthBay {Nichols & Thompson,1985a!.

Potamilla sp. [SABELLIDAE] This worm was first collected in June 1989at ShermanLake in the western Delta by the California Department of Water Resources.It has been found from Frank'sTract and the Old River in the Deltadownstream to Grizzly Bay,and is most commonat or just upstreamof the confluenceof the Sacramentoand SanJoaquin Page47 Introduced Species

Rivers,where it hasreached densities of over 16,000/m2 W. Fields, pers. comm., 1995;DWR, 1995!. Its absencefrom Delta samplings in previousdecades suggest a relativelyrecent introduction. It was probably introduced inballast water.

Pseudopolydorakempi Southern, 1921! [SPIONIDAE] SYNONYMS:Neopygospio laminifera Berkeley & Berkeley,1954 Pseudopolydorakempi californica Light, 1969 PseudopoIydorakempijaponica Imajima & Hartman,1964 Thisspionid worm has been reported from Mozambique, India,Japan and the KurileIslands, in watersranging from marine salinities down to 6 ppt Light,1969!. It wasfirst collected in the eastern Pacific in 1951at Nanaimo, British Columbia, and laterfrom False Bay, San Juan Island 968! in WashingtonandYaquina Bay 974!, NetartsBay 976! and Coos Bay 977; JTC, pers. obs.! in Oregon.InCalifornia it appearedinMorro Bay 960!, Bolinas Lagoon 967!, San Francisco Bay972!, and BodegaHarbor, Tomales Bayand Anaheim Bay 975! references inCarlton, 1979a, p.310!. Many of these sites have received shipments ofthe oyster Crassosfrea gigas fromJapan, possibly containing thisworm. Alternatively it couM have been transportedin ballast water or shipfouling. Light969! found that the California specimens more closely resembled Indianthan japanese P.kempi. In CaliforniaP. kempi occurs intertidally and subtidallyonmud and sand. It has been collected inSan Francisco Bayfrom the far SouthBay to thewestern end of CarquinezStrait Light, 1977, 1978!.

Pseudopolydorapaucibranchia$a Okuda, 1937! [SPIONIDAE]

SYNONYMS:Polydora paucibranchiata P,paucibranchiata wasdescribed from Japan. It was first reported from Australiain 1973 Carlton, 1985! may also be present in NewZealand. It was reportedfrom Los Angeles Harbor in 1950and thereafter from other southern Californiasites: Newport Bay in 1951,San Diego Bay in 1952,Alamitos Bay in 1958, AnaheimBay and Santa Barbara in 1975,and Mission Bay indensities up to 60,000 individuals/m2!by1981 Carlton, 1979a; Levin, 1981!. It was collected in South San FranciscoBay Hunters Point and Oakland Inner Harbor! in 1973,Elkhorn Slough, BodegaHarbor and Tomales Bay in 1975 where it "may be the dominant spionid polychaeteonmany sand flats," Blake, 1975!, and Netarts Bay, Oregon in 1976 Light, 1977;Carlton, 1979a,p. 312!. Summarizingrecent studies, Light 978, p. 200!showed P. paucibranchiata collectedfrom the South Bay to thewestern end of CarquinezStrait. It mayhave beenintroduced to the northeasternPacific in ballastwater or in fouling on ships, possiblyrelated to increasedship traffic during or afterthe Korean War, or with japanese oysters, Introduced Species Page 48

Sabacoelongatus Verrill, 1873! [MAI.DANIDAEj

BAMBOO WORM

SYNONYMS:Asychis elongata Asychisarnphiglypta Ehlers! Maldane elongata Maldanopsiselongata Brachioasychis colmani Brachioasychis americana

This common"bamboo worm" is native to the westernAtlantic from Maine toFlorida, the Gulf of Mexicoand British Honduras Light, 1974!. It wasfirst reportedfrom south San Francisco Bay in 1960 Berkeley & Berkeley, 1960! and probablycollected in the 1950s Carlton, 1979a, p. 324!.It isnow extremely common, typicallyfound in concentrationsof 10-1,000individuals/m~ at moststations from the far SouthBay to mid-SanPablo Bay, and in concentrationsof 1,000-5,000 individuals/m2alongthe eastern shore of the Central Bay. It isnot found upstream of SanPablo Bay Hopkins,1986!. Light974! suggested that Sabaco was introduced with Atlantic oysters. As therehad been no systematic subtidal benthic sampling inSan Francisco Baysince the 1912-13Albatross survey, it is conceivablethat it wasa lateintroduction with oystersin the 1920s or 1930sand overlooked for 30 years. Alternatively, it may have been introduced with ballast water.

Streblospiobenedicti Webster, 1879 [SPIONIDAEj

SYNONYMS:Streblospio lutincola Hartman, 1936 Sfreblospiobenedicti is common in thewestern Atlantic, ranging from the Gulfof St.Lawrence to theGulf of Mexicoand Venezuela, and is alsofound in northernEurope and the Mediterranean andBlack seas. It was collected atBerkeley in SanFrancisco Bay in 1932,in Tomales Bay and Bodega Harbor by 1936,and in subsequentyears in severalother estuaries south to Newport Bay and north to Grays Harbor,Washington records in Carlton, 1979a, p. 314!.As with Polydora ligni, the otherspionid discovered inSan Francisco Bayin the1930s, Streblospio could have beenintroduced with Atlantic oysters with which it occurson the Atlantic coast; Wells,1961; Maurer & Watling,1973!, in ballastwater, or possibly in shipfouling, andmoved along the Pacific coast with shellfish transplants or coastal shipping. In SanFrancisco Bay Streblospiobenedicti has been collected from the far SouthBay to Antioch,commonly at densitiesof 1-10,000individuals/m in the channelsand up to 50,000or moreindividuals/m2 in near shore areas, especially in constrictedcmbayments Light, 1978; Hopkins, 1986!. It is oneof themost common benthicorganisms inthe shallows ofSan Pablo Bay and the channels ofthe South Bay Nichols & Thompson,1985a!.

MOLI.VSCPa GASmar OD Busycotypuscanaliculatus Linnaeus, 1758! [MELONGENIDAE]

CHANNELED WHELK SYNONYMS:Busycon canalicutatum Busycon pyrum Thechanneled whelk, a nativeof thewestern Atlantic from Massachusetts to Florida,isnow by far the largest snail inSan Francisco Bay.As discussed byCarlton 979a!,Stohler 962! stated that the whelk was first collected inthe Bay at Alameda in1948, but specimens from Berkeley atthe California Academy ofSciences may havebeen collected asearly as 1938. There are records and frequent observations of thewhelk on the eastern shore of theBay from Alameda and Bay Farm Island to Berkeley,andon the western shore from toCandlestick Point.One specimenwascollected in1953 from the Tiburon Peninsula inMarin County Stoh]er,1962, Carlton, 1979a, p. 397!. Thechanneled whelk feeds on bivalves, It produces distinctive strings of egg casesthat release crawling nonplanktonic! snails. Natural dispersal may be achievedby floating egg cases, one string of which was collected atBolinas Lagoon. Thewhelk may have been introduced toSan Francisco Baywith some of the later andsmaller shipments ofAtlantic oysters with which it occurson the Atlantic coast;Wells, 1961; Maurer & Watling1973!, but could also have been released from a private or schoolaquarium.

Cipangopatudinachinensis matteata Reeve, 1863! [VIVIPARIDAE]

CHINESE MYSTERY SNAIL

SYNONYMS;Vivi parus malleatus Cipangopaludina matteafa V ivipar us stelmap hor us Bourgui gnat A longhistory ofrevisions anddisagreements overidentification, reviewed herewith regard to Bay and Delta area specimens, leaves it unclear whether one or two or possibly more! species ofJapanese orChinese viviparids have been introduced into California. In 1S92Wood reported buying live snails from Japan ata Chinesemarket in SanFrancisco, ata priceof tencents per dozen, and found "that each specimen containedinside, from twelve to eighteen young shells." The snails were identified Introduced Species Page50

by W. J. Raymondas Palttdina japonica Martens. Wood's specimens were later separatedby Tien-ChienYen at theCalifornia Academy of Sciencesinto threelots identified as Vivipttrus japonictts,Viviparus japorticus inakarva and Viviparus stelrrtaphorus.The last of theseis accomparuedby Wood'sbusiness card with the notation:"Bought alive for 10cents a dozenat a Chinesevegetable store on Wed. morning, Nov 18/91- Camefrom China."Stearns 901! describedWood's snails as "being part of the first lot brought alive from Japan,where they arecollected in the rice-fields near Yokohama, and are sold for a few cents a quart." Sorenson950! recalled purchasingViviparus tnalleaftts in Fresno's Chinatownin 1895which "had beenimported from Chineserice fields to Fresnofor the thousands of Chinese vineyard workers there." In 1901Stearns reported receivinga few snailsfrom the SanJose or Mt. Hamilton area"a year or more ago." One living specimenwas examinedand identifiedby Pilsbry as "Vivipara steltrtaphoraBgt. =V. malleataRve.!." Later Hannibal 908! found no viviparids in the Mt. Hamilton area, but between San Joseand San FranciscoBay collected snails identified by Dali as Viviparalecythoides Bensen. He reported theseas "introduced by the Chinesefifteen or twenty yearsago" and "cornrnonwhere planted,but spreadsslowly." A few yearslater, Hannibal 911! reportedthat on re-examination both these snails and Wood's snails in Raymond's collection were Viviparrts rnalleatusReeve, which he said were "brought from Yokohama and originally plantedbetween Alameda and Centervilleta small town 18 miles eastof Fresno]to supply the markets of San FranciscoBay...whence colonies have been distributed to a numberof points in the Sacramento-SanJoaquin Valley as well. This is verified by specimensfrom an irrigating ditch near Fresno."However, Hannibal reported that he also found Vivipara japonica, "readily distinguished from malleafus," in an irrigation ditch at Hanford, about 30 miles southeastof Fresno. The first record of introduced viviparids within the study zone consists of five shells at the California Academy of Sciences,labeled as malleata,collected from a sloughnear Holt in the Delta in 1938.Other specimensfrom within or near the Delta include eight snails collected from a canal north of Stockton in 1933,three snails from Victoria Island in 1941,eight snails from SycamoreSlough in 1946, and two undated snails from a slough near Stockton, all labeled as rnalleata.Greg 948! reported finding a few live and many broken shells of Vivipara malleatain irrigation ditches near Stockton, speculating that muskrat may have been eating the snails. Sorenson 9SO! reported collecting Viviparus rttalleatusfrom an irrigation canal 60 miles northwest of Fresno in 1948. Also, the wet collections at the California Academy of Sciencesinclude two viviparid snails labeled Bellamya japo»ica that were collected at Stockton in 1968. Hanna 966!, referred all existing western North America records to Viviparus stelmaphorus,based on finding enoughvariation in shell morphology in specimensfrom a singlelocality to encompassrecords that had beenreported as rnaileata,japonica, irvakawa or lecythoides.He reported that the snailswere still for sale in San Franciscomarkets and very abundant throughout the Delta and in irrigation canals, and in Mountain Lake and Stow Lake in San Francisco. Taylor 981! assignedthese various California records to two species, Bellamyajaponica including Wood's1891 market specimens,Hannibal's 1911 Page51 Introduced Species Hanfordrecord, and records from Mountain Lake! and Cipangopaludina chinensis rnalleata apparently including allother California records known tohim!, which helisted as occurring in irrigation ditches, sloughs and ponds from the Central Valleyand San Francisco Bayarea to southern California. Hereported both species presentin Californiasince 1891. Basedupon these records, weconclude thatthe Chinese mystery snail is establishedin the study region. The current distribution and status of theJapanese mysterysnail placed inBellamya byTaylor 981! and in Cipangopaludina by Turgeonetal, 988!! remains tobe determined in the Bay area. Viviparidsnails from these one or more species have been reported from manyother North American locations, including: theChinese market atVictoria, BritishColumbia Pilsbry k Johnson,1894!; Muddy River in Boston'sFenway from 1914to at least1942!; Worcester, Massachusetts 917!; Philadelphia 925!, at St. Petersburg,Florida and near Niagara Falls 942!; Ottawa, Sioux City, Iowa and Seattle943!; near Agassiz, British Columbia collected by1948, but reportedly plantedin1908!; Lake Erie 940s!; Jefferson County, Washington 964!;and Hawaii by1976! La Rocque, 1948; Abbott, 1950; Mills et al., 1993; and specimens atthe CaliforniaAcademy ofSciences!. These snails are both used as food items and commonlysoldby dealers ofaquarium fish, which has Undoubtedly helped to spreadthem La Rocque, 1948; Abbott, 1950!. They were reportedly introduced to SanduskyBay, Lake Erie to feed channel catfish in the 1940s, and became so abundantbythe 1960s that they were a nuisancetocommercial seine fisherman, whoreported sometimes catching two tons in a singleseine haul Wolfert & Hiltunen, 1968!.

Crepidttlaconvexa Say, 1822 [CALYPTRAEIDAE]

CONVEX SLIPPER SHELL

SYNONYM[:Crepidula glauca Say, 1822 Thisslipper shell is native to the western Atlantic, where it isfound from NovaScotia to Floridaand Puerto Rico. It wasfirst collectedin SanFrancisco in 1898,from oyster beds, and was almost certainly introduced inshipments ofAtlantic oysters with which it occurs onthe Atlantic coast; Wells, 1961!. InSan Francisco Bay Hopkins986! reported Crepidula spp. mainly from the South Bay, where C. canvexais commonly found on shells of thenative oyster Ostrea Iurida and the Atlanticmudsnail Ilyanassa obsaleta. It is notknown from any other Pacific coast site Carlton, 1979a,p. 370!.

Crepidulaplana Say, 1822 [CAI.YPTRAEIDAE]

EASTERN WHITE SLIPPER SHELL introducedSpecies Page52

Crepidulaplana is nativeto the western Atlantic with a recordedrange from PrinceEdward Island to SouthAmerica. It wasfirst reported on the PacificCoast fromthe eastern shore of San Francisco Bay in 1901,where it wasprobably introducedwith shipmentsof Atlantic oysters with which it occurson the Atlantic coast;Wells, 1961!, and was found in WillapaBay and Puget Sound in the 1930sand 1940s Carlton, 1979a, p. 376!.C. plana is similar to and may be mistaken for the nativeflat slipper shells C. perforansand C. nummaria,and in factwent unreported in theBay, though occasionally collected and misidentified or unnoticed,for many decadesafter its initialsighting. It is foundconsiderably further into the estuary than thenative slipper shells which are restricted tothe outer, more marine portions of theCentral Bay. On boththe Atlantic coast and in SanFrancisco Bay, C. plana is commonon the insideof hermitcrab-occupied snail shells,

Ilyartassaobsoleta Say, 1822! [NASSARIIDAE]

EASTERN MUDSNAIL

SYNONYMS: Rassarius obsolefus

This mudsnail is native to the westernAtlantic from the Gulf of St. Lawrence toFlorida, It wasintroduced tothe Pacific Coast with shipmentsof Atlantic oysters it isreported from oyster beds on the Atlantic coast; Wells, 1961!, and was first collectedin SanFrancisco Bay in 1907from beds of Atlanticoysters at Alameda. Carlton979a! suggeststhat it wasprobably introduced between 1901 and 1907, as its presencein the Baywas unlikely to have been missed for very long due to the intensiveactivities of shellcollectors in thearea beginning in the1890s. Ilyartassahas also established breeding populations in Willapa Bay, Washingtonand Boundary Bay, British Columbia, first reported in 1945and '1952 respectivelybut possiblypresent for a considerabletime earlier,It hasalso been reportedfrom but apparentlynot established populations in five additionalPacific Coastsites, as discussed byCarlton 979a, p. 404!:Tomales Bay 920s-1930s?!, "BolinasBay" 920s or earlier!, Humboldt Bay 930!, Birch Bay, British Columbia 950s!,and one specimen from 968!. Ilyanassaistoday the dominant mudflat gastropod inSan Francisco Bay Nichols& Thompson,1985b!, and is also sometimesabundant m salt marshesand marshsloughs and on pilings. Hopkins 986! reported it mainlyfrom the southern partof theSouth Bay and from San Pablo Bay, and we havealso seen it abundantat Alameda.Although intensively studied in theAtlantic with, for example,studies demonstratingsignificant effects on mudflat community structure and sediment composition Grant, 1965; Sibert, 1968!!, there has been relatively little work on the PacificCoast. Ilyanassa is listed or mentionedin many faunal surveys and checklists andbird diet studies e. g. Painter 966! lists it an important food of diving ducks, butWilliams 929! and Moffitt 941! found it tobe a minorornegligible food for Californiaclapper rail!, and a fewstudies contain brief notes on its ecology Carpelan,1957; Filice, 1959a; Quayle, 1964a; Vassallo, 1969!. Itsdistributional ecology Page53 Introduced Species inLake Merritt is the subject ofan unpublished master s thesis Gilmore, 1935!. GrodhausandKeh 959! found it to harbor five species oftrematode flatworms, includingtheschistosome Austrobilharria variglandis whichis responsible for "swimmers'itch." Race 979, 1982! demonstrated competitive displacernent and predationofthe native hornsnail Cerithidea califorrtica, asdiscussed inChapter 6.

Lit farinasaxati lis Olivi,1792! [LITTQRINIDAE]

ROUGH PERIWINKLE Thiscommon north Atlantic snail was first collected inSan Francisco Bayby J.Carlton inMay of 1993 onthe shore ofthe Emeryville Marina. Thissite is adjacent toa publicboatramp and dock, and L.saxatiIt's waslikely introduced inthe seaweed usedtopack live marine baitworms shipped fromMaine and discarded byanglers. Wehave repeatedly found live L. saxatitis inthe seaweed Ascophyllum rtodosum andoccasionally otherfucoid seaweeds! packing baitworms shipped toNewport Bay andSan Francisco Bay Carlton, 1979a; Lau, 1995; ANC, pers. obs.!. As many as over a millionMaine baitworms areshipped tothe Bay Area each year Lau, 1995! packed inseaweed containing many millions ofliving invertebrates frommany phyla, so thatthis may be a transportvectorof some significance alsosee Miller, 1969!. Wehave irregularly visited and collected a total ofabout 100 live Littorina saxatifisfrom the shore ofthe Emeryville Marina, where the snails were abundant intertidallyin1993 and 1994, andscarce in1995, inthe crevices ofrocky debris along about10 meters ofshoreline. They have not been observed. elsewhere in the Marina orthe Bay. They produce "crawl away" larvae, andcould spread aseggs orsnails on rafting seaweed.

Melanoidestuberculata Miiller, 1774! [THIARIDAE]

RED-RIM MELANIA

SYNONYMS:Thiara tuberculata Melanoidestuberculata is a freshwatersnail native to theregion from Africa tothe East Indies. It was introduced tothe United States through theaquarium trade andwas first reported from California in1972 from adrainage ditch in Riverside County Taylor, 1981!, TheCalifornia Department ofWater Resources hascollected it fromseveral sites in theDelta since December 1988, atdensities ofup to 754 snails/m2 DWR, 1995!.

Urosalpinxcinerea Say, 1822! [MURICIDAE!

ATLANTIC OYSTER DRILL IntroducedSpecies Page54

Urosalpinxcirterea is nativeto the northwesternAtlantic from the ;ul f of St. Lawrenceto Florida.It was introducedin shipmentsof Atlanticoysters to San FranciscoBay, where it wasfirst collected from oyster beds at Belmontm 189p Steams,1894!. It hasbeen collected from many other bays in thenortheastern Pacific,and is currentlyestablished in BoundaryBay, British Columbia first record 1931!,southern Puget Sound 929!, WillapaBay 948!, TamalesBay 935! and NewportBay pre-1940s?! Carlton, 1979a, p. 384!.As Urosa/pirtx's larvae are not pelagic,most of thesesites represent either independent introductions from the Atlanticor intracoastal,human-aided transfers from other bays, including commercialshipments of oystersand other bivalves along the coast.Within San FranciscoBay, Hopkins 986! reportedUrosalpinx only from the SouthBay. Urosalpirtxeats barnacles, mussels and bryozoans as well as oysters.Although in some studies the drill has apparently preferred barnaclesor musselsto oysters Haydock,1964; Carlton, 1979a!, its impactson oysters,especially on oysterspat, can be substantial Haydock, 1964!.

Booneabisufuralis Say, 1821![PYRAM!DElLIDA]

TWO-GROOVE ODOSTOME

SYNONYMS: Merjesfho bisufuralis Odostomia bisufuralis Odostomia fetella

Boo@ca bisufuralis is native to the western Atlantic from the Gulf of St. La~ rence to Delaware,where it is an ectoparasiteboth of the Atlantic oyster Crassosfreavirginica and of a number of bivalvesand gastropodsthat were transported to San FranciscoBay with shipmentsof Atlanticoysters. It was reported in San FranciscoBay in 1977associated with the Atlantic rnudsnailIlyanassa obsoletaand the native hornsnailCerithidea californica on the Fremont shore Race,pers. comm.!, and reportedas commonon a far SouthBay mudflat Nichols & Thompson, 1985b!. Odosfomiafetella reported from SanPablo Bay Filice, 1959! and Suisun Bay Markman, 1986!may also be this species,Carlton 979a, p. 435! arguesthat Bootteabisuturalis was probablyintroduced with oystershipments in the 19th or early 20th century, and remainedunreported because of incomplete systematic work on the Odosfomiacomplex in the northeasternPacific. He predicts that early collections of Bootteabisuturalis and possiblyother speciesof Atlantic odostomids will be found when unsorted, unidentified or misidentified material in museum collectionsis systematicallyworked up by specialists. Although, basedon its associations, was probably an introduction with oyster shipments that remained unrecognizedfor many year's, it might possibly have been a later introduction in ballast water. Introduced Species Poge55

Catriortarickettsi Behrens, 19S4 [TERGIPEDIDAE] SYNONYMS:Trinchesia sp. Behrensh Tuel, 1977 Catrionarickettsi was first collectedin SanFrancisco Bay from Pete's Harbor, SanMateo County in 1974,where it isassociated with and presumably feeds on the hydroidTubularia crocea Behrens iceTuel, 1977; Behrens, 1984!, and was subsequentlycollected from La Jolla Behrens, 1980!. In1995 it was collected on Tubulariamarina on the oceanside of theUmpcIua River jetty in Oregon0. Goddard,pers, comm., 1995!, The most likely means introduction isin ballastwater or transportedaseggs on ship fouling. Its origin is unknown.

Cuthonaperca Marcus, 1958! [TERGIPEDIDAE]

LAKE MERRITT CUTHONA In California,Cuthona perca is knownonly from Lake Merritt, where it feeds onthe introduced Japanese anemone Hatiptarteita lineata Carlton, 1979a, p. 431,as Trinches~'asp.!It is reported from Brazil, Jamaica, Miami, Barbados, NewZealand andHawaii Behrens, 1991!, The most likely mechanisms of transport are either in ballast water or as eggson ship fouling,

Eubra<1chusmisakiensis Baba, 1960 [EUBRANCHIDAE]

MISAKI BALLON AEOLIS Eubra>fichusmisakensis was describedfrom Japanin 1960and collected at the SanFrancisco Municipal Marina in !962 Behrens, !97!; Gosliner, 1985!. It occurs on boatfloats and docks and silty-clay bottoms throughout the Bay, where it isfound withand apparently feeds on the hydroid Obelia, Carlton, !979a, p.433; Behrens, 1971,1991!. It tnay have been introduced inballast water or as eggs on ship fouling, orpossibly with shipments ofJapanese oysters and overlooked fora few decades.

Okeniapla~ia Baba, 1960 [GONIODORIDIDAE]

FLAT OKEIVIA Page56 Introduced Species

Okeniawas f'rst ~eported from San Francisco Bay by Jom Steinberg in 1960 thes meye r itwas described from Japan!, based on coi}ectior in the195ps. It has ahobeen rePorted from San Qnofre, Qrange County Goslmer, 1995!. It occurson floatsand pilings among fouling and with egg cases on a membraniporidbryozoan tentativelyide tifiedas Conopeumterruissimum!, on rock on mudflats,an ubtidallyinSan Francisco Bay,where it hasbeen reported f om the South Bay palo AltoYa&t Harbor, Crown Beach in Alameda!,Central Bay Berkeley pier anc} Yacht Harbor,San Francisco Yacht Harbor! and San pablo Bay Pont Richmond and China Camp! Carlton, 1979a, p.425' ANC, pers. obs.!. Carlton 979a! suggests that it was Probab}ymtro«~ withshiPPing from Japan, either in ballast water or as eggs on fouling,PehaPs related toincreased trans-Pacific shiptraffic during and after the KoreanWar. Alternativelyit coulcihave been introduced with shipmentso japaneseoysters and overlooked for a coupleof decades

Philirte auriformis Suter, 1909 [PHII INIDAE]

TORTELLINI SNAIL Philirteauriformis is native to NewZealand and possibly southern Australia, and was first identified from San FranciscoBay in july, 1993.It had beencollected fromthe South Bay for about a yearprior to itsrecognition as an introduced species i.e.since about the summer of 1992!in trawlsby theMarine Science Institute of RedwoodCity, USGS and CDFG K. Grimmer,J.Thompson and K. Hieb,pers. comm,!,By 1994 it wasregularly collected in ottertrawls and benthic samples from theCentral Bay P,Donald, pers comm.;ANC, pers. obs.!, and snails and. egg masses whichsuccessfully hatched in the laboratory!were collected from intertidal mudflatsin BodegaHarbor, 120 km northof theentrance to SanFrancisco Bay, in April,1994. As it isnot known from fouling, Philine was probably introduced to California via ballast water Gosliner, 1995!. All specir.;enswere taken from fine,silty mud, Stomachs contained fragmentsof bivalveshells, Nutricula =Transennella!tarttilla artd N. confusein BodegaHarbor and possibly the introducedbivalve Gemma gemma in San FranciscoBay Gosliner,1995!.

Sakuraeolisenosimertsis Baba, 1930! [FACELINIDAE]

WHITE-TENTACLEDJAPANESE AEOLIS SYNONYMS:Coryphella sp. Behrens,1980 Sakuraeolisertosimertsis is native to japan and was first collectedin FranciscoBay in 1972,It is commonand widespread in the southern portions of San FranciscoBay Gosliner,1995!, where it feedson thehydroid Tubularia crocea Introduced Species Page57 growingon boat docks Behrens, 1991!. It couM have been introduced in ballast wateror as eggson fouling.

Tenelliaadspersa Nordmann, 1845! ]TERGIPEDIDAE]

MINIATURE AEOLIS

SYNONYMS: pallida Alder & Hancock,1854! Fmbletoniasp. Alder & Hancock,1851 Tenelliaadspersa is widespread in Europeanand Mediterranean waters and recentlyreported from Chesapeake Bayand Brazil, with a single2 mm specimen reportedfrom Japan Carlton, 1979a!. Itwas first collected from the Pacific Coast of NorthAmerica at PointRichmond in SanFrancisco Bay in 1953,and laterfrom the Richmondand Berkeley Yacht Harbors, Lake Merritt, , Sausalito andSouth Beach Harbor, San Francisco Carlton, 1979a, p. 428;Jaeckle, 1983; ANC, pers.obs.!. It is now known from Coos Bay to Long Beach Gosliner, 1995!. In Europeit is reported torange from waters ofocean salinity to"quite fresh water"and feedsvoraciously on a varietyof hydroidsincluding the freshwater hydroidCordylophora caspia Roginskaya, 1970!, which is introduced toand commonin theDelta. In SanFrancisco Bay Tenellia adspersa apparently feeds on theintroduced hydroids Tubularia crocea Carlton, 1979a; Behrens, 1991! and Obelia dichotoma Jaeckle, 1983!. Carlton 979b! suggested that it wasprobably introduced fromEurope by shipping,either in ballast water or as eggs on fouling.

~ulmonata Ovatellamyosatis Draparnaud, 1801! [MELAMPIDAE]

SYNONYMS:Alexia sefifer Cooper, 1872 Alexiasetrfer var. tenuis Cooper,1872 Phytia myosotis Ovatellamyosotis occurs on both coasts ofthe north Atlantic, but may have beenintroduced to the westernAtlantic in the late18th or early19th century Berrnan& Carlton,1991!. It wasfirst collected from San Francisco Bay in 1871, probablyintroduced with Atlantic oysters, although possibly carried inwet ballast or wedgedinto holes or cracks in the wooden hulls of sailing vessels. Failure tofind it earlierin SanFrancisco Baydespite intensive prior sheU collecting in the area, plus theinitiation of Atlanticoyster shipments with the completion ofthe transcontinentalrailway in 1869, suggests that Q. myosotis wasintroduced notlong beforeits discovery,probably in 1869-1871. 0, myosotiswas collected inHumboMt Bay in 1876, in San Pedro Harbor in southernCalifornia in 1915,and in Washingtonstate in 1927.It hasnow been Introduced Species Pnge58 recordedfrom numerous Pacific coast bays and estuaries horn Boundary Bay, Britis ColumbiatoScammons Lagoon, Baja California Carlton, 1979a, p. 414!-Since 0 osotislac s planktoruclarvae. theseadditional sites resulted from transport eitheron coastalshipping or in replantingsof oysters,or fromseparate introductions from the Atlantic. 0 myosotisis absent from Pacificcoast Pleistocene deposits but thereis one anomalous report by Gifford916! of thissnail in anaboriginal shellmound on the shoreof SanFrancisco Bay. Carlton 979a!doubts this is pvatella,and Gifford's material has been lost. 0, myosotisis euryhalineand livesunder boards and debris near the high- tideline of saltmarshes and protectedbeaches in lagoonsand bays. The snail has beenstudied in Europebut largely ignored in NorthAmerica. On thePacific coast it hasbeen reported from the stomachsof willets Catoptrophorussemjpalmatus! Stenzelet al., 1976!.Carlton 979a! notedthat its co-occurrence in variousPacific coastsites with severalspecies of nativeand introduced snails provided suitable systemsfor the study of competitiveinteractions between native and introduced species.Herman and Carlton991! founddietary overlap with the nativesnails Assimirteacalifornica and Littorina subrotundatain CoosBay, Oregon, but no evidenceof competitivesuperiority by O. myosotis,and concluded that its establishment was not at the expense of the nativesnails,

MOLLUSCA: Arcuafulademissa Dillwyn, 1817! [MYTILIDAEf

RIBBED MUSSEL, RIBBED HORSE MUSSEL

SYNONYMS: lschadium demissum Modiolus demissus Geukensia demissa Volsella demiss us Brachidontes dernissus Modiolus plicatulus Lamarck, 1819

Arcuatula demissa more commonlyknown as Ischadjumdemjssum on the Pacific coast and as Geukensia demissaon the Atlantic coast! is native to the northwestAtlantic, commonly found in saltmarshes from the Gulf of St. Lawrence to North Carolina, Southward it is replacedby a subspecies,Arcuatula demissa granossisjmum.It wasfirst collected in the Pacificfrom south San Francisco Bay in 1894 Stearns, 1899!, probably introduced with Atlantic oysters small Arcuatula are commonlyfound on oystersm the Atlantic;Wells, 1961; Maurer 8z Watling, 1973!. It has sincebeen collected from four othersites: Newport Bay first collectedin 1949!, AlamitosBay 957! andAnaheim Bay 972! Reish,1968, 1972; Carlton, 1.979a, p. 440!.Questionable or probably adventitious specimens from other Pacific coast bays arediscussed by Carlton979a!- Introduced Species Page 59

Arcuatulahas becomeone of the most abundantbivalves in San Francisco Bay.De t root927! reported that "countless millions of thesesmall mussels cover theedges and sometimes theentire bottoms ofthe gutters and creeks ofthe west Bay marshes."Pestrong 965! found in thePalo Alto area that they "effectively rip-rap channelbanks when they form in largecolonies, as is oftenthe case."Carlton 979a,b!found Arcuatula lining the base of concreteretairung walls at LakeMerritt, a brackishlagoon in Oakland.Arcuatmla is common and often abundant in salt marshesfrom the South Bay to San Pablo Bay, where it frequentlylies embedded withits posterior margin protruding above the mud. This"endobyssate" habithas resulted in a curiousreported effect on the endangeredCalifornia clapper rail Rallieslongirostris obsoletus!. UeGroot 927! reportedthatthe toes orprobing beaks ofrails are caught and clamped between the exposed,slightly gaping valves ofthe mussel. Hereported thatalmost every rail examinedover the preceding twenty years was missing one or moretoes, presumablyfromthis cause, that others had had their beaks clamped shutand died of starvation,and estimated that an average of oneor two chicks per brood were caughtby mussels and drowned bythe incoming tide. More recent observers note thatclapper rails in SanFrancisco Bay are frequently missing one or more toes Moffitt,1941; Josselyn, 1983; Takekawa, 1993!, and Takekawa 993! reported that a railcaptured inthe Palo Alto marshes with a musselclamped onto its bill subsequentlylostpart of its bill, On the other hand, Moffitt 941! found that Arcuafala formed 57 percent byvolume ofthe total food in 18 clapper rail stomachs thathe examinedin 1939,and Recher 966! andAnderson 970! recorded Arcr~afulafrom the stomachs of willet anddunlin in the SouthBay.

Corbicnlafluminea Muller, 1774! [CQRBICULIDAE]

ASIAN CLAM, ASIATIC CLAM

SYNONYMS:Carbicula fluviafalis Muller, 1774! Corbicularnanilensis Philippi, 1841!, Corbicula leana Prima, 1864! and Corbiculasinensis as reportedin NorthAmerica, and many other namesin Asia;see Prashad 929!, Morton979!, Britton& Morton 979!, andWoodruff et al.993! for extensive synonymies This freshwaterclam is nativeto China,Korea and the UssuriBasin in southeasternSiberia Ingram, 1948!, with closely related and possibly conspecific populationsinJapan Britton & Morton, 1979!. The earliest North American record consistsof three shells collected on thebeach at Nanaimo,British Columbia in 1924, thoughno further specimens have been reported from Canada Counts, 1981!. Corbiculawas next collected from the mouth of theColumbia River in 1938 McMahon,1982!. It was reported from the Delta in 1945 Hanna, 1966! and v idespreadthereby 1948 Ingram, 1948!, and reached theImperial Valley in southeasternCalifornia by 1952 McMahon, 1982!. Introduced Species Page 60

From southernCalifornia Corbicula spread eastward to Arizona by 1954 Ingram,1959!, and to nearEl Pasoin westTexas by 1964 McMahon,1982!, Meanwhile,Corbicrtla was collected from the Ohio River near Paducah, Kentucky in 1957,which McMahon982! suggestsinitiated a secondzone of dispersalirt North America.By theend of the 1960sCorbicula had spread through the lower Mississippiand Ohio river valleys, into southeastTexas and Oklahoma, and along the Gulf coast from Louisiana to southern Florida, and by the mid-1970shad spread up theMississippi Valley to northernIowa andalong the Atlantic coast from Florida to New Jersey.By the early 1980s,Corbtcula was found in 35 of the United Statesand in northernMexico McMahon,1982!. Corbicrtla was reportedfrom South America,France and Portugalin 1981,and a specimenwas collectedfrom a in Oahu, Hawaii in 1992 Araujo et al., 1993;Burch, 1994!. Althoughfor many yearsthe Corbicttlain North Americawere describedas belongingto at leastthree different species, in 1979Britton 6 Morton argued that only one species is involved, the highly variable Corbicttlaflutrtirtea, a view that has generally been acceptedsince. Corbicuiafrom California, Texas, Arkansas, Tennesseeand South Carolina showed no genetic variation between populations at 18 loci, 14 of which were polymorphic in some Asian Corbicttla Smith et al., 1979!. SinceCorbicrtla are cultivatedand soldas food in many Asian countries, many researchershave suggestedthat it wasdeliberately introduced to establisha food resource e. g. Ingram, 1948;Hanna, 1966;Britton k Morton, 1979;McMahon, 1982!,or possiblyintroduced throughthe aquariumtrade Ingram et al., 1964!.Some researchershave suggestedthat it was introducedwith Japaneseoysters Burch, 1944; Hill, 1951;Filice, 1959!,but sinceCorbicrtla is mainly a freshwaterorganism, this seems unlikely. Corbicrtla'sspectacular spread within and betweenwatersheds in North America may have resultedfrom transportfor useas bait, food or aquariumpets, or in river gravels dredged for use as aggregate Ingram et al., 1964!,although McMahon 982! argues that natural meansof dispersalwere paramount,including passivedownstream transport of juvenilesin currents,upstream transport in fish stomachs,and upstream or between-watershedtransport on birds. Corbiculaare fairly hardy,tolerating several months without food Hanna,1966! and 7-27 days out of water McMahon,1979!. One specimen was mailed, dry, in an envelopefrom Pennsylvaniato Washingtonstate for identificationand mailed back without ill effect McBane,pers. comm., 1995!. The use of Corbiculain aquacultureor for wastewaterclarification, in either commercial or experimentalapplications as on St, Croix, Virgin Islands Haines, 1979!, may serveto introducethe clam to new locationsin the future. Corbiculais today the mostwidespread and abundantfreshwater clam in California, found throughoutlower elevationwaters, the dominantmollusk and the third most abundantbenthic organism in the Delta, and one of the most commonly identifiedbenthic organisms in fish stomachs Gleason, 1984; Herbold & Moyle,1989!. Densities of 2,000young clams/m2 are common, and range up to 20,000/m-'.Spring flows carry young Corbicrtla down to Suisun Bay where they are sometimescollected as far westas Martinez,but high fall salinitiesappear to prevent Page6I Introduced Species theestablishment oflarge adult populations evenin the western Delta Hazel & Keliey,Populations1966; Evans ofetCorbicttlaal., 1979; withMarkmann, typical 1986!.densities of10,000 to20,000 clams/m2 witha maximumof131,200/m ! trapped sediment andformed extensive barsin theCentral Valley Project's Delta-Mendota Canal,reducing delivery capacity and. requiringexpensive dewatering andthe dredging ofover 50,000 cubicyards ofclam- bearingmaterial. Onebar was described asfilling the bottom ofthe canal from 0.3-1.0 meterdeep for3 kilometers Hanna,1966; Eng, 1979!. Ingram 959! reported the clamasan economic pestofwater delivery systems inCalifornia, infesting and impairingoperation ofunderground pipes,turnout valves, laterals andagricultural sprinklersystemsin the Coachella andImperial valleys, andplugging thetubes of condenser-coolerunitsat the federal government's TracyPumping Plant in the Delta.Corbicula isfrequently citedas a significantproblem infouling irrigation systems,municipal watersystems, powerplant steam condensers, emergencyreactor coolingsystems andservice water systems elsewhere inthe country e.g. Ingram et al.,1964; Sinclair, 1964;Hanna, 1966; Goss k Cain, 1977; McMahon, 1977,1982; Mattice,1979; Goss et al., 1979; Parsons, 1980!. Corbiculaisalso reported torender river sand and gravel unfit for use as aggregate,andtooutcompete nativeunionid andsphaeriid clams McMahon, 1982!. Bluecatfish, Jctalurtts furcttttts, were introduced tosome California waters inpart to controlUpperCorbicu!a, salinity buttolerances without success forCorbicttla Gleason, flumittea1984!. havebeen reported at14 ppt Gainey,1978!, 13-17 ppt Morton h Tong, 1985!, andabout 10ppt without acclimationand22-24 ppt with acclimation Evanset al,, 1979!. Sparse populations of Corbictilahave been observed in the San Francisco Estuary near Martinez at17 ppt, andabundant populations inareas subjected todaily salinities of10 to 12 ppt Evans et a l1979!.Corbiculaflttmitrea areviviparous, releasing benthic pediveliger larvae or planktonicveligers thatbecome benthic within 48 hours Eng, 1979!. There are typicallytw;ospawning periods peryear, with one study reporting peakproduction ofover 300 larvae/clam/day andan average of1,140,820 larvae/m>/year. Biomass productivityrateswere the highest everrecorded fora freshwaterbivalve,and higherthan most marine bivalves Aldridge & McMahon, 1978!, InCalifornia there are modest market sales ofCorbicula both for bait and for food Gleason, 1984;commercial harvesting forfood isallowed only in inKern County!. Itwas noncommercially harvestedfrom the Delta for food atleast asearly as 1946 Hanna, 1966!,

Gemmagemma Totten, 1834! [VENERIDAEj

AMETHYST GEM CLAM

SYNONYMS:Gemma purpttrea Lea, 1842! Page62 Introduced Species Thissmall, viviparous clam, native to thenorthwestern Atlantic from Nova Scotiato Floridaand Texas, was first reported from the Pacific coast as 42 specimens recoveredfrom the crop of a duckbought in a SanFrancisco market in 1893.It was collecteddirectly from the Bay in thelate 1890s, from Solinas Lagoon in 1918 and fromthree other nearby embayments Bodega Harbor, Tomales Bay and Elkhorn Slough in the1960s and 1970s Carlton, 1979a, p.490!. Earlierobservations of Gemmagemma in theseembayments could have goneunremarked because ofconfusion withthe small native venerid Transenttella tantilla.The early records from San Francisco Bay noted above were originally identifiedas Trartsertrtella, andmany later reports of Gemmagemma from various Pacificcoast embayrnents andoffshore sites were based on material that on re- examinationturn out to beTransettrtella or one of twoother native clams Carlton, 1979a!.Gemmagemma was probably introduced with Atlantic oysters, which it commonlyoccurs on the Atlantic coast Wells, 1961; Maurer & Watling,1973!. It is abundanton theintertidal mudflats from the far SouthBay through San Pablo Bay whereit is oneof themost common benthic species, in placesreaching rnidsumrner densitiesof over 400,000 individuals/m2 Nichols & Thompson,1985a, 1985b! and is occasionallyfound up through Suisun Bay Hopkins, 1986!. It has been found in the stomachsoften species ofshorebird in San Francisco Bay Recher, 1966!, ofwhite sturgeon McKechnie 8zFenner, 1971!, and possibly ofthe introduced nudibranch Philitteouriformis Gosliner, 1995!, isreported asan important food of diving ducks Painter,1966!, and is undoubtedly eaten by many other organisms. Oglesby 965! suggestedthatGemma gemma may be the first intermediate hostof the trematode Parvatremaborealis. The trematode makes characteristic pits in theshell of Gemma gemma,and such pits have been found in shellsfrom San Francisco Bay, Bolinas Lagoonand Tomales Bay Carlton,1979a!.

Lyrodttspedicella.'its Quatrefages, 1849! tTEREDINIDAEj

BLACKTIP SHIPWORM SYNONYMS:Teredo diegensis Bartsch, 1916 from SanDiego Teredotorortsertdi Bartsch, 1922 from San Francisco Bay manyother synonyms from other parts of the world Turner, 1966! Lyroduspedicellatus is a warm-temperate andsubtropical wood-boring shipwormthat requires temperatures of14 to 24'C and salinities ofat least 29 ppt to breed Eckelbarger & Reish, 1972!. It has been reported from many parts of the world the easternand western Atlantic, the Indo-Pacific region, Australasia, South Africa,Japan and Hawaii and its origin is unknown, having been early and widely distributedeither by drifting wood or in thehulls of ships.It hasrepeatedly been "discovered"and described asa newspecies: 12times in theAtlantic, and 21 times in the Pacific Turner, 1966;Carlton, 1979a,p, 551!. Page63 Introduced Species A shipworm,apparently Lyrodus, w~ reportedfrom Wil ingtonHarbor nowpart of the Los Angeles-Long BeachHarbor system! in1871 and following years,and Lyrodus wascollected fromSan Diego Harbor by1876. Itwas subsequently veryabundant inthese harbors Miller, 1926!. It was collected from San Bruno Sloughinsouth San Francisco Bayin 1920, from Klkhom Slough in1935, and from severalsouthern California bays and ports beginning in the 1940s Carlton, 1979a!.

Macomapetafum Valenciennes, in Humbold & Bonpland, 1821! []

BALTIC CLAM SYNONYMS:Macoma balthica of SanFrancisco Bay authors Macomaincartspicua of SanFrancisco Bay authors ThisMacoma species in SanFrancisco Bay has heretofore been known as Macomabatthica. In recent decades, M balthicahas generally been regarded as a singlespecies with a circumboreal/arcticdistribution, withrecords from central Californianorth to Alaskaand the Bering Sea, the Okhotsk and Japan seas, the Beaufortand Siberian seas, the Barents and White seas, northern Europe, the mid- Atlanticstates north to westernGreenland, Hudson Strait, Hudson Bay, and BathurstInlet in theCanadian Archipelago. However, the analysis of shell characteristicsandgrowth rates Beukema & Meehan, 1985! and allozymes Meehan, 1985;Meehan et al., 1989! clearly indicates the existence of twospecies, one native to thenorthv estern Atlantic herecalled Macoma petalum!, the other native to the northeasternAtlantic and northern Pacific Macomabalthica!. Basedon recentstudies, the smallpink Macomaof SanFrancisco Bay, long thoughttobe native Macoma balthica, appears rather to be M. petalum introduced from the northwesternAtlantic. Tested at elevenloci, the allelefrequencies of San FranciscoBay specimens closely resembled those of northwestern Atlantic M. petalum Nei's 978! unbiased genetic identity of 0.943!,and differed sharply from thoseof M. balthicafrom Alsea Bay and Coos Bay, Oregon genetic identity of 0.394- 0,461! Meehan et al., 1989!. Genetic identities >0.9 are generally thought to occur amongconspecific populations, of0.5-0,8 among sibling species, and of <0.5among non-siblingspecies Meehan et al., 1989!. Theearly history of Macoma battbica and petalum in SanFrancisco Bay remainsto be workedout. Shells identified as M. balthicahave been recovered from 2,000-6,000year old sedimentsunder San Francisco Bay. It maybe that Macoma balthicathen died out in the Bay, as Meehan etal. 989} argued based on the lack of recordsfrom later sediments and aboriginal shell middens in theregion. Clams, apparentlyreferable toM, balthica orpetalttm, were collected inthe Bay by the UnitedStates Exploring Expedition in 1841and by variousparties in the1860s Carpenter,1857, 1864; E. Coan, pers. comm., 1995!. They were found to be common in all partsof theBay in theAlbatross survey of 1912-13 Packard, 1918}. Clamscollected prior to 1850could represent Macoma balthica native to the Bay,if an aboriginalpopulation persisted despite Meehan et al.'sarguments; or Page64 IntroducedSpecies couldrepresent M,balthica fromfurther northan the Pacific coastor M. pefalutrt fromthe northwestern Atlanticintroduced insolid ballast. Clams collected after 1850transplantscould inofadditionthe native representoyster OstreaM balthicacortchaphila from northern =lttrida!. baysClamsintroducedcollected with after 1869could inaddition represent M.petatttm introduced withshipments afthe AtlanticoysterCrassostrea virginica.Morphologic Beukmak Meehan, 1985!or geneticTheanalysiscurrent of museumdistributional specimenspatternmight ofMacorrtasort some balthica ofthese and possibilitiesMacorrta petalttrnout. inthe northwestern Pacific,particularly betweenSan Francisco Bayand Coos Bay, alsoremains tobe determined. SouthofSan Francisco Bay,there are records of shellsandpossibly livespecimens of"Macama batfhica" as far south asSan Diego, butthese appear tobe sporadic occurrences, probablyrelated toanthropogenic transport,Macomaratherpetatum than establishedor batthica haspopulations.been collected throughout SanFrancisco Bay upstreamtoCollinsville, especiallyinthe shallows wheredensities havereached over'1,000 individuals/m~ Siegfriedetal., 1980; Hopkins, 1986;Markmann, 1986!, and Nicholshas been& aThompson, dominant 1985a!.benthicItcan organismbe an importantin South Bayfood andof fish,Suisun divingBay ducksshallows and clapperrail Williams, 1929;Painter, 1966!,and formed 8percent ofthe volume of foodin18 clapper railstomachs Moffitt,1941!. In San Francisco BayMacorrta feeds onboth planktonic andbenthic rnicroalgae, andThompson & Nichols988! found supplythattheandtiming highand mud-flatrate of growthair! temperatures,of intertidal andpopulationsindependent wasofcontrolled salinity averby fooda 0-31 ppt range,Itwas recently determined thatMacotna balthicafrom both Vancouver Island andthe Baltic Seahost thesame three species ofdigenean flatworms Pekkarinen k Ching,1994!,It would beof interest todetermine whetherMacortta pefatumfrom SanFrancisco Bayand the northwestern Atlantichost the same ordifferent parasites.

Musctdistasenhousia Benson, 1842! [MYTIUDAE! SYNONYMS:Muscutus senhottsia Modiolusdemisstts of Filice 959! NativetoJapan andChina, thissmall mussel wasintroduced toWashington andcentral California withJapanese oysters Crassostrea gigas!,with which it has beenWashington,found inonincoming beds ofJapaneseseed Kincaid, oysters1949!.in1924, Itwas and collectedat Olympia inSamish in1959. Bay,In central Californiaitwas collected fromTomales Bayin1941, Bolinas I.agoon in1944, San FranciscoBayin1946, Elkhorn Slough in1965 and Bodega Harbor in1971. Itwas collectedfromMission, SanDiego andNewport baysin southern California, and PapiloteBay near Ensenada! m BajaCalifornia inthe 1960s and1970s Carlton, 1979a,p.449!, probably transported inballast water oron ship orboat fouling. Inthe Page65 introduced Species 1970sitappeared inNew Zealand andAustralia andin the 1980s m the Mediterranean,Inthe western paclfrc Mrrscrrtrsfa I s been reported atdensrtres ofUp to 28,650 juveniles/m~settledoneelgrass or2,500-2,800 adults/mjust buried inthe mud of thetidal flats, where theclams build nest about them ofbyssal thead, mucus and sediment.Musculista isused as food inChina and as fish bait and as feed for cultivatingshrimpand crab inJapan Morton, 1974;Carlton, 1979a!. Onthe bottom ofLake Merritt, a shallow, brackish Lagoon onSan Francisco Bay,Musculista occursindense byssal matsthat can bepulled from the bottom in sheets,andas individuals among thefouling onpilings and floats. AtAlameda individualsarefound nesting inthe sediment orattached tothe base of eelgrass plants.Mrrsculista hasbeen collected atdensities ofup to 1,000-2,000 clams/m~from theSouth Bay to San Pablo Bay, where it has frequently beenone of the most commonbenthic organisms, andoccasionally collected upstream toHonker Bay Nichols& Thompson, 1985a,Hopkins, 1986;Markrnann, 1986!.Crooks 996! has investigateditsecology andbiology inMission Bayin southern California.

Myaarenaria Linnaeus, 1758 [MYIDAE]

SOFT-SHELL CLAM SYNONYMS:Mya hemph ill ii Newcomb,1874 Myaarenaria isnative tothe American Atlantic coast and from Alaska north ofthe Aleutian Peninsula, although its distribution north of British Columbia isnot wellknown. It has been introduced into western and northern Europe. Although recordedfrom Miocene and Pliocene deposits on the Pacific coast, ithas not been foundin Pleistocenedeposits orin aboriginalshell middens south ofthe Bering Sea, andhad not been encountered bynumerous collectors on the Pacific coast prior to 1874 Stearns, 1881!. Inthat year itwas collected inSan Francisco Bay Newcomb, 1874!,almost certainly transported there in the transcontinental shipments of Atlantic oysters that began in 1869. Thislarge, edible clam was soon transplanted toother Pacific Coast sites e. g. CoosBay, Oregon by1880, Santa Cruz, California by1881, Willapa Bay and Puget Soundin Washington by1884 and 1888-89; also note Stearns' 881! exhortation that "itwould be a wise, public spirited act if thecaptains ofour coasting vessels would takethe trouble and incur the slight expense attending theplanting ofthis clam at suchpoints as their vessels touch atin the ordinary course ofbusiness"!, andmay havebeen distributed to others with transplantings ofoysters from these sites or withfresh introductions ofoysters from the Atlantic. It is less likely, though possible,thatMya arenaria's appearance insome locations resulted from deliberate introductionsfrom the Atlantic which Rathbun 892!, Heath 916! and Coe 956! claimwas attempted oroccurred!, orfrom the transport ofsmall clams in ship fouling.Although some workers have suggested thatsome orall of Mya arenaria's northwardmovement was due to natural dispersal e.g. Quayle,1960!, Carlton 1ntroducedSpecies Page 66

979a! concludesthat "there is littlehard data that Mya hasever spread naturally anywherealong the Pacific coast." Mya arenaria does not appearto havebecome establishedsouth of Monterey, despite a planting of about 2,000clams in Morro Bay in 19IS and occasional,probably erroneousreports of Mya arenariafrom southern California reviewed in Carlton, 1979a!. By the 1880sMya arenariawas reported as the mostcommon clam sold in San FranciscoBay area markets Stearns, 1881! But the commercialharvest declined from500-900 tons per year in 1889-1899,to generallyabove 100 tons per yearin 1916- 1926,to nothingafter 1948, possibly due to overharvesting,habitat loss,pollution or a decline in the market due to an increasing harvest of Verterupis phillipinarum Skinner,1962; Herbold et al,, 1992!.Today, noncommercial harvest of Mya continuesfor food and bait Sutton,1981; Herbold et al., 1992!.It hasbeen collected throughoutthe Bayas far upstreamas Collinsville and Sherman Lake, frequently at densitiesover 100 and sometimesover 1,000clams/m2, and hasbeen one of the dominantbenthic organisms in theshallows of the SouthBay and SuisunBay Nichols k Thompson, 1985a;Hopkins, 1986,Markrnann, 1986!. Severalworkers reported that Mya arenariareplaced populations of the native clam Macoma rtasutain San FranciscoBay, at least in regularly harvested clambeds e. g. Fisher,1916!. Clam beds encompassing from a few to hundredsof acreswere established from the SouthBay to theNapa Riverand Martinez, some of thempublic and someprivately owned, with some fenced to keepout batrays and fiounder Bonnot,1932!, Predators of Mya arertariaon the Pacificcoast include rays, , flounder, ducksand shorebirds.Five speciesof nativepinnotherid crabs are recordedas living in Mya arenaria'smantle cavity referencesin Carlton, 1979a!.

Mytilus galloprovirtcialis Lamarck 1819 [MYTILIDAE]

MEDITERRANEAN MUSSEL

SYYONYMS;the taxonomy of the Mytilus "edulis" complexis reviewedby Koehn 991! and Seed 992!

The cosmopolitan Mytilus "edulis" speciescomplex was variously grouped into one or severalspecies by differentauthors until electrophoreticevidence published in the late 1980sand 1990sled to the generalrecognition of threespecies: M. edulis from northern Europe and easternNorth America;M. galloprovirtcialis from the Mediterranean Sea,various sites on the Atlantic coastof Europe,South Africa,California, Japan, Hong Kongand eastern China, Australia, Tasmania and New Zealand; and M. trossulus from the northwestern Pacific, Siberia, eastern Canadaand the BalticSea McDonaldet al., 1991;Koehn, 1991; Seed, 1992!, although frequenthybridization between these forms may raisedoubts about their specific status Seed,1992!. Mussels from Chile,Argentina, and the Falklandand Kerguelen islandscontain alleles characteristic of all threegenotypes but havebeen tentatively assignedto M. edulis McDonald et al., 1991!, Page67 IntroducedSpecies Thetwo species present inthe northwest Pacific have been differentiated on thebasis pf rnorphornetricanalysis Sarver & Foltz,1993; mussels from San FranciscoBaycollected in1990!, starched gelelectrophoresis at8-1S allozyme loci McDonald0 Koehn, 1988, using mussels collected in 1985-87; Sarver k Foltz, 1993!, andthe sequencing ofmitochondrial 16Sribosomal DNA Geller etal., 1993. 1994!. Allmethods agree in finding predominantly orpurely M trossulustype from Eureka,California north to Alaska; a hybridization zoneincluding Westport, TomalesBay, San Francisco Bayand Monterey Bay where sites contained various mixturesof M. frossulus,M. galloprovinciafis andtheir hybrids; and high proportionsofM. galloprovitrciafis atsites south ofMonterey toSan Diego. However,these methods differed in theirconclusions about how dominant M.galfoprovincialis issouth of Monterey, withallozyme analyses showing almost pureM. gafloprovitrciaiis genotype and DNA analysis showing a roughly equal mix ofM. galloprovincialis-M. trossulus genotypes. Geller et al. 994! suggest that this couldresult fram the introgression of the M. trossulusmitochondrial genome into individualswith M. gaOoprovincialisnucleic genome. Since mitochondrial DNA is mainlytransmitted maternally inMytilus species, such introgression could be producedby repeatedcrossings with M galloprovitrcilismaleswith a fernaleM. trossulusand her female descendants. Thepattern of occurrenceof these species suggests that M. Irossulus is a cold- ternperatespecies native to thenorthern Pacific, and that M. galfopravirtciahsisa warm-temperatespecies native to theMediterranean and introduced to California, Japan,China and South Africa Koehn, 1991; Seed, 1992!, as well as Australia, Tasmaniaand New Zealand.DNA analysisof rnuseurnspecimens indicates that M. galloprovincialisarrived in southernCalifornia between 1900 and 1947, probably as shipfouling or aslarvae in ballastwater, displacing M. trossulusg. Geller in Culotta, 1995!. DNA analysisalso showsthat viableM. galloprovincialislarvae are continuallydischarged in largenumbers into Coos Bay, Oregon in theballast water fromJapanese ships, though no adultM. galloprovincialisorhybrids were found in the bay Geller et al., 1994!. ln SanFrancisco Bay, bay mussels are found mainly from thenorthern South Bayto southernSan Pablo Bay, and occasionally as far upstreamas Martinez Hopkins, 1986!.Distribution af M, trossulusand galloprovincialis at four sitesas indicatedby allozymefrequencies show a heterogeneousmixof speciesand hybrids that follows no obvious environmental cline, with M. frossulusstrongly dominating at both the most upstreamand most seawardsite, andM. galioprovi~ciafisless strongly dominating at sitesbetween Sarver 5 Foltz,1993!. On the Pacificcoast these two difficult-tp-distinguishspecies have long been consideredone species and have been frequently used for thebiomonitoring of pollutantsin the CaliforniaMussel Watch program and other studies. Recent indicationsthat separate species in theMytilus "edulis"complex exhibit different growthrates anddifferent concentrations of various elements when grown in the samehabitat Labelet al., 1990!suggest that conclusions about the relative contaminationof varioussites based on comparativebioassays of baymussel specimensincorrectly assumed to belongto a singlespecies may be invalid.Other studiesha> e founddifferent species within thecomplex to havedifferent levels of Jntrpduced Species Page68

ectionby parasit~, spawning periods, fecundity and strength of byssal attachment Seed, 1992!.

Petrrcolar

FALSE ANGELWING

SYNONYMS:Petricola pholadtformfs

The false angelwing is native to the northwesternAtlantic, rangingfrom the Gulfof St.Lawrence to the Gulf of Mexicoand possibly to Uruguay, andhas been introducedto Europe Carlton, 1979a, p. 515!.It wascollected in southSan Francisco Bayin or before1927 Grant 8zGale, 1931!, from Willapa Bay in 1943 Kincaid,1947! andfrom Newport Bay in 1972,Reports of P. pholadtIormisRom "nearMonterey" andfrom Scammons Lagoon, Baja California are probably erroneous Carlton, 1979a!.It is a borerinto clay, peat,mud, sand and other soft sediments, and has been recordedfrom oysterbeds on the Atlanticcoast Wells,1961!. Though it was most likely introducedto the Pacific in shipmentsof Atlanticoysters, it is puzzling that it was reportedfrom the Pacific relativelylate. It is a strikingshell that would not likely havebeen overlooked by collectors.It is possiblyan early ballastwater introduction. In Willapa Bay a spionid polychaete,a Corophiumamphipod and a nereid polychaeteare often associatedwith P. pholadiformis.In San FranciscoBay, Bush 937! reportedthat about90 percentof theseclams collected from sandybeaches near the Oakland Airport host the ciliate Ancistruminakofoidi. This protozoan is knownonly fromP. pholadiform'rsfrom San Francisco Bay, and is presumedto be native to the Atlantic and introducedalong with the clam.

Potamocorbiilaamierensis Schrenck, 1867! [CORBULIDAE]

AMUR RIVER CORBULA, ASIAN CLAM

In October1986, a collegebiology class dredged three email and unfamiliar clamsfrom the bottom of SuisunBay, These were subsequently identified as Potamocorbulaamurensis, a native of estuariesfrom southern China 2 latitude!to southernSiberia 3' N! andJapan, which was likely transportedto Californiaas larvae in ballast water. By the summerof 1987 Potarnocorbulahad becomethe most abundant benthic organism in thenorthern part pf theBay, carpetingthe bottom at densitiesof over16,000 juvenile clams meanshell length of 1,7mm! per square meter Carlton e't al., 1990; Nichols et al-, 1990! It seemslikely thatPotamocorbula arrived in theBay very shortly before its discovery,because it v asnot collectedearlier despite regularbenthic sampling, encl becauseall specimenscollected through March 1987 were less than 11 ~rn long,and therefore probablyless than a yearold Carltonet al,, 1990!. Jn traducedSpecies Page 69

An intensivebenthic survey of thenorthern Bay in 1990found Potamocctrbrrlavery commonfrom San Pablo Bay through Suisun Bay, and most abundantin theSuisun Marsh region with mean concentrations of up to 19/00 clams/m2and a mediansize of 2-3 mm.Median sizewas 10-11mrn in SanPablo Bay,and S-6 mrn and 8-9 rnm in theshoals and channel ofSuisun Bay Hymanson, 1991!.Potamocorbtela isnow abundant in parts of theSouth and Central Bay, and hasoccasionally been collected in the western Delta as far upstream asRio Vista, overa rangeof salinities from 33 ppt to less than 1 ppt.At thesesites it wouldbe exposedtotemperatures ranging from 8' C onsubtidal bottoms in the winter to23' C onintertidal flats in the summer,within the temperaturerange of 0-28 C suggestedbyits latitudinal range in Asia. It livesboth subtidally and intertidally on all soft-bottomsubstrates, where it typicallysits with one-thirdto one-halfof its lengthexposed above the sediment surface Carlton et al., 1990!. Priorto 1986,the benthic species composition and abundance in the northern Baychanged markedly from year to year, with freshwater species declining during dryperiods and more numerous, higher-salinity species dominated bythe clam Mytrarertaria, theamphipods Corophittm acherusicum andAmpelisca abdita, and thepolychaete Streblospio benedictt, allintroduced organisms invading the area Nichols,1985!. Pofarrtocorbuta's arrivalin theBay followed a majorflood in the springof1986, and its increase andspread coincided with a multi-yeardryperiod thatbegan in mid-1986,The 1986 flood left the benthic community nearly depauperateinthe Suisun Bay area, probably facilitating Potatrtocorbula's establishment.Thiscornrnunity failed to return during the subsequent dryperiod, presumablydueto Potamocarbttla's presence. Themechanisms bywhich Potamocorbtelaexcluded these organisms arenot known, but could include the depletionoffood resources seebelow! orfeeding byPotamocorbula onthe larvae of theseorganisms Nichols etal., 1990!. Patamocorbula hasmaintained substantial populationsinthe northern Bayeven after the end of the drought andthe return of normalfiows 0, Thompson,pers. cornrn., 1994!, and thus appears tohave permanentlychanged benthic community dynamics inthis part of the Bay Nichols et al., 1990!. Examinationof fecesfrom specimens collected in the Bayshow Potamocorbrelaingesting both planktonic Coscirtodiscrts spp.and Skeletortema cosfatum!and benthic Navicula spp.! Carlton et al, 1990!.Werner k, Hollibaugh993! found that Potamocorbuta filtersbacterioplankton aswell as phytoplankton,thoughatlower efficiency, andassimilates bothwith high efficiency. Theycalculate thatat present densities inthe northern Bay >2,000 clams/rn2! Potttmocarbtelacouldfilter the entire water column over the channels more than onceper day and over the shallows almost 13times per day, a rateoffiltration whichexceeds thephytoplankton's specific growth rate and approaches orexceeds thebacterioplankton's specificgrowth rate, Thus Potamocorbrtla maypermanently reducethephytoplankton standingstock in the northern reachof the Bay. Alpine & Cloern992! described thepre-Potamocorbuta regimeasone in which phytoplanktonbiomassand production wereregulated byriver-driven transport whenbenthic grazers were few, but limited by grazing pressure when grazers were introduced Species Page70 ab~~dant.With Potamocorbulain the Bay,grazing pressure may be permanently h'gh, andphytop]ankton biomass and pmductlvie permanently low I" laboratoryexperiments Kirnmerer 991! found that potamocorbufareadily consumednauplii of the copepodEuryfemora afjinis, but not the introduced copepodPseudodiaptomus sp. Kimrnerer et a].994! arguedthat an observed declinein the abundanceof threedominant copepod taxa p. affinis,Sinoca]anus doer"'i,and Acartia spp. that coincidedwith the spreadof pofarrtocorbu]ain the northernreach of theBay resulted from direct predation on cppepods by Potamocorbula rather than from food limitation due to the decline in phytoplankton. Furthertrophic changes may be expected to resultfrom the reductionin zooplanktonand the build-up of potamocorbu]a,including declines in the organismsthat feedon zooplankton,and increases in organismscapable of feeding on Potamocorbula Carlton et al., 1990!.Potamocorbula has been found in the stomachsof diving ducksand sturgeonin theBay Nicholset al., 1990!,and in aquariais readily consumedby the introducedgreen crab Cohen et al., 1995!. Investigatinga]]e]e frequencies at eight ]oci, Duda 994! found high genetic diversity in the SanFrancisco Bay population polymorphicat 75 percentof sites with a meandirect-count heterozygosity of 0.295!,with little geneticdifferentiation between sites within the Bay.

Teredonavafis Linnaeus, 1758 [TEREDINIDAEJ

NAVAL SHIPWORM

SYNONYMS: Teredo beacbi Bartsch, 1921 Teredo diegensis in part! Teredojaponica Clessin, 1893 othersynonyms are reviewed by Turner966!, andthe historypf taxonomicdebate regardingSan Francisco Bay shipworrns is reviewed by Carlton 979a, pp. 558-S60! Theearliest northwest Pacific record of thisglobally-distributed, temperate water shipworm is from San Francisco Bay in 1913,and it has also estab]ished populationsin Willapa Bay, Washington first reportedin 1957!,in pendre]] Sond British Columbia 963!, and possibly in Los Ange]esHarbor 927! and other southernCalifornia bays Barrows,1917; Kofoid k Miller, 1927;Reish, 1972; Carlton, 1979a,p, 556!.It undoubtedly arrived in the hu]ls of ships. When CommodoreJohn Sloatarrived on the Pacificcoast in 1852in searchof a suitable location for the Navy Department's western shipyard, his orders directed him to pick a sitethat was "safe from attackby wind, wave,enemies, and marine worms" Lott, 19S4!.He chose the eastern shore of in the northern upstreamreach of SanFrancisco Bay, where low salinities kept the regipnfree pf marinewood-boring organisms and where marinefacilities such as wharves and Introduced Species Page71 ferryslips could consequently be built on untreatedwooden pilings, It w» in wooden structures at Mare Island that Teredortavalis, which readily tolerated much fresher water than did the existing marine borers in the Bay thriving down to 9 ppt andsurviving indefinitely down to 5 ppt;Miller, 1926!,was first noticedin 1913.By 1919-1920,possibly aided by a dryspell that brought higher than average salinities, Teredonavahos was found from the South Bay to Suisun Bay and had grown so abundantas to destroyvirtually all thewooden structures in thenorthern part of theHay, with damageestimated at overhalf a billiondollars in currentdollars McNeily,1927; this paper, Chapter 6!. This destruction led to the formation of the SanFrancisco Bay Marine Filing Committeewhich produced a seriesof reports annualreports in 1921,1922 and 1923,and the FinalReport in 1927!covering the activitiesand management of a varietyof marinewood-borers in San Francisco Bay and elsewhere in the Pacific. Theparticipants in the Committee's investigations later published several additionalpapers on. the biology and morphology of Teredonavalis references in Carlton, 1979a!. The evidence that Teredorravafis is not native to San FranciscoBay is reviewedby Harrows917, p. 29!, Kofoid 921, pp. 43-44!, Kofoid & Miller922, pp. 81-82;1927, pp. 206-207, 246-247! and Carlton 979a, pp. 560-563!. This evidence includesthe absenceof anyknown damage from marineborers in the northernpart of theBay prior to 1913,the lack of anyprior record of Teredonavalis on the Pacific coastdespite extensive collecting by nineteenthcentury conchologists, and the failure to find Teredonavalis in an investigationof shipwormsconducted for the United States Forest Service in 1910-1911. Althoughthe specific source of theshipworms introduced to SanFrancisco Bayis unknown,Carlton 979a! suggests that Teredo navalis is nativeto the Atlantic.A shipworm,probably Teredo navafis but possiblyNotateredo rtrjrvegica Turner,1966!, was known. from Europe since at leastthe start of the 17thcentury andwas apparently mentioned by Pliny,Cicero, Theophrastus and others in ancient times Moll, 1914!.Teredo rtavalis was reported from Europe in 1731by a Dutch commissiondescribing a "horribleplague" of shipwormsthreatening to destroythe dikesthat protected the lowlands of Holland,and by Sellius in 1733Teredo navalis wasalso present in Japanat least since the 1890s, though it appearsto havebeen absent from Australia at that time Carlton, 1979a!. Althoughthere has been little noticetaken of shipwormsin SanFrancisco Bayin recentyears, New York City has apparently experience a resurgence of shipwormactivity reportedly resulting from a cleanerharbor or, less likely, from shipworrnsdeveloping a tolerance to creosote!. When city officials visited the BrooklynArmy Terminal in thespring of 1993to inspectshipworm damage they foundthat one of thepiers had collapsed the previous night. The city spent $100 millionto protectits piers against woodborer damage Gruson, 1993!.

Theorafragilis A. Adams,lSSS [SEMELIDAE]

ASIAN SEMELE Tntrad~eed species Page 72

SYNONYMS: Theora lubrica Gould, 1861 Theorafragilis is a small,mud-dwelling clam native to Japan,China, the Indo-West Pacific and New Zealand. It first appearedin the northeastern Pacific in southern California, where it was collected from Anaheim Bay in 1968-69,from Newport Bayin 1971-73,and in largenumbers from Los AngelesHarbor in 1973 Seapy,1974, Carlton, 1979a, p. 517!.It wasprobably introduced in ballastwater, possibly from ships returning from SoutheastAsia during the VietnamWar. Theorafragilis larvaehave been collected from the ballastwater of Japanesecargo shipsarriving at CoosBay, Oregon and rearedto juverulestages Carlton et al., 1990, p 85!. Theorawas first collected in San FranciscoBay in 1982at Islais Creek, San Francisco Carlton et al., 1990!.It occurs in small numbers through much of the Bay, the California Department of Water Resourceshas collected it at Point Pinole at densitiesof up to 127/m2since sampling began in 1991 DWR,1995!, and it was one of the most common benthic organisms collected at the Alameda Naval Air Station in 1993 G. Gillingham,pers, comm.!. It is absentfrom SuisunBay accordingto U. S. GeologicalSurvey sampling records Carltonet al., 1990!.

Venerupis philippinarum Adams & Reeve, 1850! []

JAPANESE LITTLENECK CLAM, MANILA CLAM

SYNONYMS:Tapes japonica Deshayes,1853! Tapes semidecussafaReeve, 1864 Tapes philippi naram Ruditapes philippinarum Paphiabifurcata Quayie, 1938

Ve»erripis philippinarum, known until recently as Tapesjaponica, is an Asian clam that was introduced with shipments of Japaneseoysters to the northeastern Pacific, where it has become establishedin numerous bays from British Columbia to central California and is the numerically dominant clam in many of them. It was first noticed in planted oyster beds in SamishBay, Washington in 1924 Kincaid, 1947!,and in a shipment of Japaneseoysters arriving at Elkhorn Slough in 1930 Bonnot, 19351!,However, the first record of an establishedpopulation on the North American coast is from Ladysmith Harbor on the eastern shore of Vancouver Island, British Columbia in 1936 Quayle, 1938!.Northward spread from that site, and later northward spread from Barkley Sound on the west side of Vancouver Island to Venerupis'northernmost record in HecateStrait, appearto have been due to the transport of larvae by currents, but the clam's spread southward to California is probably due in large part to new introductions in oyster shipments from Japan, to the transplanting of oysters along the coast, and to intentional transplants some probably not recorded! of Venerupis, Page73 introducedSpecies Verterupiswasfound inPuget Sound in1943, inWillapa Bay and San FranciscoBayin 1946, inBodega Harbor and Elkhorn Slough in1949, inTomales Bayin 1955, inHumboldt Bayand Grays Harbor in1964, and in Bolinas Lagoon in 1966.It had entered the commercial market by 1941, which encouraged laboratory aquacultureeffortsand reseeding andreplanting programs inthe Pacific northwest, someofwhich continue, Efforts were made to establish Venerupis inMorro Bay, NewportHarbor andthe Salton Seain 1953, inthe Queen Charlotte Islands in1962, andin Yaquina andTillamook baysin 1965, allof which failed. However, itwas successfullyestablished inNetarts Bay,Oregon inthe 1970s Carlton, 1979a, p.502!. InSan Francisco Bay, Verterupis iscommonly found at concentrations upto 2,000clams/m2 from the South Bay through SanPablo Bay, where itis one of the mostcommon benthic organisms, andhas on occasion been found as far upstream asChipps Island Nichols k Thompson, 1985a;Hopkins, 1986!. Inthe Bay itis collectednoncommercially bothfor food and bait Sutton, 1981; ANC, pers. obs.!. InSan Francisco Bayand elsewhere, Venerupis co-occurs withvarious native clams,including thesimilar native littleneck clamProtothaca starninea. Although a fewauthors have stated that Verterupis displaces thenative littleneck, others have seenlittle evidence ofcompetition between them, with Venerupis living higher in theintertidal zone or closer tothe surface than Protothaca seeCarlton, 1979a!. However,the question hasnot been effectively studied. A varietyoforganisms feedon Venerupis onthe Pacific coast, including the rnoonsnailPolinices tewisii, sturgeon, willet, gulls, ducks and raccoons Glude, 1964; Painter,1966; McKechnie & Fenner, 1971;Stenzel etal,, 1976; Carlton, 1979a!, and undoubtedlymany others.

ARTH ROPODA: CRUSTACEA

Erisarsietlazostericola Cushman, 1906!

SYt ONYttS: Sarsiella zostericola Sarsiefla fricosiata Jones, 1958 Thiswestern Atlantic ostracod occurs from Maine to Floridaand in the Gulf of Mexico.It is known on the Pacific coast only from San Francisco Bay, where it was firstcollected in 1953 at Point Richmond Carlton, 1979a, p.573!, It iswidely distributedinthe Bay on soft substrates inshallow water. It has also been introduced toEngland, where itoccurs onlyin regions where Atlantic oysters wereplanted. Thoughnotrecorded fromSan Francisco Bayuntil the 1950s, thisminute, ben.thic crustaceancouldhave been long present butgone unnoticed orunrecognized, and thusmay have been introduced withAtlantic oyster shipments. Sinceostracods otherthan holoplanktonic ostracods! haverarely been collected fromballast water samples e.g. Carlto~ k Geller, 1993!, ballast water seems a less likely transport mechanism, liitroduced Species Page74

~Coi~eisa Acarfiella sinensis

This copepod,native to the subtropicalto tropicalwaters of the China coast, wascollected in SuisunBay in 1993,1994 and 1995. It isfound in thevicinity of the entrapmentzone and doesnot extendupstream as far as the easternDelta Orsi, 1994,1995; J. Orsi, pers.comm., 1995!. It was probablyintroduced in ballastw-ter.

Limnoifhona sinensis Burkhardt, 1912!

SYNONYMS: Oithona sinensis

This copepodhas been collected from the brackishand freshwaters of the YangtzeRiver Changjiang!inland to at least300 km and fromnearby lakes and canalsin 1898,in 1906and prior to 1962.It wascollected from the SanFrancisco Estuaryfor firsttime in 1979,by CDFGfrom the San Joaquin River near Stockton Ferrari& Orsi,1984!. Herbold & Moyle989! suggest that a declinein zooplankton abundancein the Deltaprior to 1979may have facilitated L. sinensis'establishment. It has beencollected throughout the Delta where it is more abundantin the San- Joaquinthan in theSacramento River! and downstream to Suisun Bay, though apparentlyrestricted to watersof lessthan 1.2 ppt Herbold& Moyle,1989!. It has beenmost abundant in Oct./Nov.and scarcest in Mar./Apr., with a maximum recordedabundance of 71,176individuals/m2 in Aug., 1981near Stockton Ferrari & Orsi,1984!. In 1993-94it wasreplaced over its entire range by Limnoifhonafefraspina J, Orsi, pers. comm.,1995! The lack of any recordof thiscopepod in theeastern Pacific prior to 1979,and earlyrecords of it fromthe YangtzeRiver area, suggest that L. sinensisisa recent introductionto the San Francisco Estuary Ferrari & Orsi,1984!. It wasmost likely transportedacross the Pacificin ballastwater oithonidcopepods have been found to survive transportin ballasttanks; Carlton, 1985,p. 346!.

Li m noithcna f etraspi na Thiscopepod, native to theYangtze River, was first found in theEstuary in 1993at in SuisunBay and at Collinsvilleand Hood on the SacramentoRiver. By 1994 it hadreplaced Limnoithona sinensis and, reaching densitiesgreater than 40,000/m3, had become the mostabundant copepod ever seen in theEstuary Orsi, 1995; J. Orsi, pers, comm., 1995!. It wasprobably introduced in ballast water. Page75 1mtraduced Species

Mytilicolaorientalis Mori, 1935

PARASITICCOPEPOD SYNoNYMs:Mytilicola ostreae Wilson, 1938 Thissmall red copepod livesin the intestine orrectum, orrarely inthe digestived,iverticulae, ofoysters and other mollusks. Itis native tothe western Pacificandwas introduced tothe northeastern Pacificwith shipments ofthe JapaneseoysterCrassostrea gigas,ltwas first collected fromWillapa Bay, Washingtonin1938, and subsequently frommany bays and estuaries from VancouverIsland, British Columbia toMorro Bay, California, including San FranciscoBayin 1974 where it was discovered inthree out of 30 native oysters Ostreacortchaphi7a fromthe , Bradley k Siebert, 1978;Carlton, 1979a,p.577!. These various sitescould have received Mytilicola directlywith shipmentsofoysters fromJapan, withoysters transplanted fromother eastern Pacificbays, or with rnussels fouling coastal ships. Onthe Pacific coast Mytilicola hasbeen found in inaddition toJapanese oysters!theintroduced slippershell Crepidula fornicata one record fromPuget Sound!,andseveral native bivalves, including theoyster Ostrea conchaphila, the musselMytilus californiartus, andthe clams Protothaca staminea onerecord from PugetSound!, Saxidomus giganteusand Cfirtocardircm rtuttallii one record each fromBritish Columbia!. It hasalso been found inthe native mussel Mytifus trossulus northern records reported asM edttlis! and possibly theintroduced musselM.gal1aprovirtcialis orin hybrids San Francisco Bayrecord reported asM. edulis;see Sarver k Folz,1993! Carlton, 1979a!. Carlton979a! notes that the data for sites and for hosts may be selective as "allbays that have been searched, andmost if not all mollusks thathave been examined,havebeen found tohave Mytilicola." Healso notes that due to the copepod'sendoparasitic habitand a lackofexploration andearly collecting, Mytilicolacould have been inthese bays long before itwas first observed. Katanskyetal. 967! and Bradley 6 Siebert 978! summarize thebiological researchon Mytilicalain theeastern Pacific.

Oithona davisaeFerrari & Orsi, 1984 Thiscopepod wasfirst collected ineastern Suisun Bayin 1979, and described byFerrari &Orsi 984!. Ithas been collected fromthe South Bayto San Pablo Bay, andupstream toChipps Island inwaters of12 ppt. Copepods thatwere collected fromSan Pablo Bay in the winter, spring and fall of 1963 and identified asOithorta sp.may also have been Oitharta davisae Ferrari k Orsi, 1984!. Ambleret al. 985!found Oithorta davisae to be one of themost common copepodsinthe Bay in1980, InJune toDecember ofthat year, atsites from theSouth BaytoCarquinez Straititwas found in25-48 percent ofthe samples collected, and Jntrodueed Species Page76

reachedpeak abundances of 22,ppp-44,pppindividuals! m2 in theSouth Bay in October and November. Ferrarik Orsi984! argued that the lack of any record of this copepod in the Bayprior to 1979, and the fact thatsome distinctive morphological characters are sharedexclus'vely with Indo-WestPacific oithonid copepods, suggests that Oitporta davisaewas a recentintroduction to theSan Francisco Estuaqr from the western Pacific.It wassubsequently found in Japanesewaters, where it isfrequently abundantin eutrophicembayments Uye > Sano,1995!, and considered to be of Asianorigin Flerninger & Kramer, 1988!. It hasalso been reported from southern Chile Carlton,1987!. Oithona species have been found to survivetransport in ballasttanks Carlton, 1985, p. 346!,and this one was most likely transported across the Pacific in ballast water.

Pseudodiaptomusforbesi Poppe & Richard,1890!

Pseudodiaptomusforbesi is native to the fresh and brackish waters of the YangtzeRiver Changjiang!, China, usually restricted to waters of lessthan 8 ppt.It was first collected outside of China in 1987in fresh water in the eastern and southernDelta. By thefollowing year it wasfound throughout the Delta and downstreaminto Suisun Bay up toa salinityof 16ppt, in whichareas it wasthe most abundantcalanoid copepod in the fall of 1988and in 1989.The maximum abundancerecorded was 22,408 individuals/m~ in fresh water in theSan Joaquin Rivernear Stockton in earlyJune, 1988 Orsi, 1989; Orsi & Walter,1991!. Varioushypotheses have beenproposed to explainthe recentdramatic shifts in theabsolute and relative abundanceof Pseudodiaptomusforbesi and other copepodsin thenorthern reach of theEstuary, including competition between nativeand introducedcopepods, differential predation by introducedfish and clams ondifferent copepods, and predation by copepods on other copepods. Herbold et al. 992!, implying competitionas the relevantmechanism, reported that the "invasionsof the westernDelta and SuisunBay by Sinocalanusdoerrii in 1978and by Pseudodiaptomusforbesi in 1987were followed by declinesin abundanceof Eurytemoraaffinis and the almostcomplete elimination of Diaptomus spp." On the otherhand, Kimmerer 991! reportedthat the cryptogenic copepod Eurytemora affiniswas not food-limited irt theEstuary so that competition with recently introduced copepodscould not accountfor its decline. Orsi989! noted that striped bass appeared tobe more effective predators on Eurytemorathan on P. forbesi, and Meng & Orsi991! found that striped bass larvae in laboratoryfeeding experiments selected native copepods Cyclops sp, and cryptogenicEurytemora present in the Estuarysince at leastthe 1912-13Albatross survey;Esterly, 1924! over the recently introducedcopepods P. forbesi and Sirtocalanusdoerri, and suggested that differences incopepod and escape behaviorscould account for the differentialpredation. Kimrnerer 991! reported that in laboratoryexperiments the introducedAsian clam Potamocorbula artturensis consumedEurytemora but not Pseudodiaptomusspecies, and Kirnmerer et al. ]994! arguedthat the decline in Ererptemorawas caused by Potamocorbula preying on its IntroducedSpecies IPagc77 nauplii.Orsi 995! suggestedthat, in additionto predationby Potamocorbula,the declinemay have been partly due to competitionwith P.forbesi, noting that Kurytemoracontinues to be seasonallypresent in winterand springwhen P. forbesi is scarce,both within and upstreamof Potamocorbula'srange. Orsi 995! also suggestedthat predation by theintroduced copepod Tortanus sp. may account for a declinein Pseudodiaptomusin westernSuisun Bay in 1994.

Pseudodiaptomusmarinus Sato, 1913!

Pseudodiaptomusmarinus is native to China, Japanand PacificRussia, and has beenintroduced to Hawaii and MauritiusO'ones, 1966; Grindley k Grice, 1969; Orsi et al., 1983!.It was collectednorth of SanDiego in MissionBay in 1986and in AquaHedionda Lagoon in May 1987 Flemingerk Kramer,1988!. It wasfirst collectedin the SanFrancisco Estuary from westernSuisun Bay in 1986,and has beencollected from there upstreamto Collinsvilleon the SacramentoRiver, in waters with surfacesalinities ranging from about 2 to 18 ppt. It hasalso been collectedfrom TomalesBay Orsi 8eWalter, 1991!. Pseudodiaptomusmarirtus may have been introducedto San FranciscoBay in ballast water, to the southernCalifornia bays or TomalesBay in oystershipments, and movedbetween bays by coastalcurrents Fleminger 8z Kramer, 1988; Orsi k Walter,1991!, Heminger & Krarner{19SS! suggested that the native copepod P. euryhalirtusmay havebeen displaced by P. marirtusin southernCalifornia embayments,and calledfor moresampling to determinewhether P. euryhalinus was in fact absent or confined to sites where P. marinus had not become established.

Siuocalauus doerrii Brehm, 1909!

SYNDNYMS:Sinocalartus mystrophorus Burckhardt, 1913

Thiscalanoid copepod is nativeto the riversof mainlandChina, and like the otherpelagic copepods described here was probably introduced in ballastwater. It wasfirst collectedfrom theEstuary near Pittsburg in 1978and soon became from 1979to the early1980s! the most abundant copepod in the Delta,with maximum densitiesof over10,000 individuals/m2 and greatest densities from June to September.It has been collected from throughout the Delta upstream to Hoodon the SacramentoRiver and Stocktonon the SanJoaquin River, and downstream to SanPablo Bay, generally at salinitiesbelow 5 or6 pptbut on occasion up tonearly 15 ppt.Its downstream limit xnay be regulated by both salinity and the location of the entrapmentzone Orsi et al.,1983; Ambler et al.,1985; Herbold & Moyle,1989; Orsi, 1995}.It wasnot collected in 1994,but reappearedin 1995Q. Orsi, pers- comm, 199'!- Five speciesare recognizedin the genusSittocalarrus, all from the northwestern Pacific. As 5. doerrii had not been collectedin regularplankton surveysin theEstuary in 1963and from 1972-78, it was probably introduced shortly before1978 via ballastwater Orsiet al,,1983!. Orsi et al.suggest, based on the Introduced Species Page 78

apparentpattern of spreadin 1978-79,that thesite of introductionwas in the Pittsburg-Antiocharea near where S. doerrii was first collected.They further suggest that waterpumped out of the Deltainto the CaliforniaAqueduct will carryS. doerrii to waterproject near Los Angeles, and that theColumbia River and Puget Soundare likely sitesfor secondaryintroductions via the ballastwater carried by coastal ships. Several researchers have considered interactions between Sinocalanus doerrii and other copepodsin the northernestuary someof which are discussedabove under PseudodiaptomusIorbesi!. Orsi et al. 983! noted that competition between Sinocalanusand the cryptogenic copepod EurytemoraafPnis was unlikely because their preferredsalinity rangesdiffered, and suggestedthat competitionand/or predationbetween Sinocalanus and the freshwatercopepods Cyclops and Diaptomuswas a stronger possibility and should be investigated. Ambler et al. 985! questionedwhether there is competitionfor food, at leastin yearswith average river dischargeand diatom blooms in Suisun Bay. Meng & Orsi 991! found that striped basslarvae in laboratory feeding experimentsselected Cyclops sp. and Euryfemora over Sirtocalartus. Herbold et al, 992! reported that the introduction of Sinocalanusand of Pseudodiaptomusforbesi in 1987 was followed by declines in Euryfemora and the almost complete elimination of Diaptomusspp., although Herbold & Moyle 989! had earlier suggestedthat declines in Delta zooplankton prior to 1979may have facilitated Sinocalartus'establishment. Kimmerer 991! reported laboratory studies indicating that although Sinocalartusmay be food limited in the estuary in some years, Eurytemorais not and so competition with recently introduced copepods could not account for Eurytemora'sdecline. Orsi 995! suggestedthat Sirtocalanus had "apparently slipped into an unoccupied niche" between Euryfemora downstream and Diaptomus speciesupstream in the San Joaquin River, but noted that Diaptomus abundance fell when Sirtocalanusspread upstream. Herbold k Moyle 989! had noted that the invasion of the SacramentoRiver by Sirtocalanus coincided with a reduction in the relative abundanceof chlorophyll in the north Delta.

Tor tan us sp.

This large calanoid copepod of unknown origin was collected in Suisun Bay in the fall of 1993and in 1994 Orsi, 1994,1995; J. Orsi, pers. comm., 1995!.It preys on other copepodsand Orsi 995! suggeststhat it may have causeda decline in Pseudodiaptomusin western Suisun Bay in 1994.Its prior absencein this well- studied region of the Bay suggeststhat it was introduced in ballast water. fntroduced Species Page79

Qg~ Balanusamphitrife Darwin, 1854

STRIPED BARNACLE

SYNONYMS:Bafanus amphifrife amphitrife Darwin, 1854 Balanus amphitrife hawaiiensis Broch, 1922 Balanus amphifrife denficufafa Broch, 1927 Balanus amphitrife her@iRogers, 1949 Balanus amphitrifefranciscanus Rogers, 1949 Balanus amphifrife salfonensisRogers, 1949 Thissubtropical and warm-temperate barnacle is nativeto the Indian Ocean but hasbeen distributed widely. In perhapsthe earliest scientific recognition of the phenomenonof marine introductions, Darwin 854, pp, 162-163! noted that Balanusamphitrife, B. improvisusand a fewother barnacles "which seem to range overnearly the whole world excepting the colder seas!" may have been transported to partsof theirreported range as foulingon ships. B.amphifrife was collected in Hawaiiin the early1900s. In Californiait was foundin La Jollain 1921,in SanDiego in 1927,in SanFrancisco Bay in 1938-39,and in theLos Angeles/Long Beach area in 1940 Zullo et al., 1972; Carlton, 1979a, p. 585!. In 1945it was found in the SaltonSea, probably introduced from SanDiego Bay attachedto "navyplanes, boats, buoys, ropes, or othermarine equipment that was transferredin large quantity to thesea for training purposes" Carlton, 1979a!. It was first collected from the Gulf of California and the west coast of Mexico in 1946,and appearedon theAtlantic coast of NorthAmerica after World War Il, AlthoughBalanus amphi rifetolerates water temperatures down to 12'Cit requiresat least18'C to breed. It maythus be restricted to warmersites within San FranciscoBay, where it hasbeen collected from scatteredlocations in the northern SouthBay, Central Bay and San Pablo Bay Newman,1967!. In Britainand the Netherlandsit livesin areasheated by the outflow from power plants Vaas,1978; Carlton, 1979a!.

Balanus improvisus Darwin, 1854

BAY BARNACLE Balanusimprovisus, a nativeof the North Atlantic,is themost freshwater- tolerantof thebarnacles and has been widely introduced around the world. It is also the earliestknown introduction to SanFrancisco Bay, having been identified from a musselshell in U. C, Berkeley'sMuseum of Paleontologythat wascollected from the harborof SanFrancisco in 1853 Carltonk Zullo, 1969!.This early introduction wasprobably the resultof transportas fouling on ship hulls. B. improvisusis nextknown in SanFrancisco Bay from specimenson the shellof an Atlanticoyster, Crassostrea virginica, collected at SanMateo in 1900,and introduced Species Page80 thebarnacle then appears in collectionsfrom every decade of the twentiethcentury, oftenon oysteror musselshells Carlton k Zullo,1969!. A secondintroduction and possiblyadditional introductions! of B.improvisus, with shipmentsof Atlantic oystersthat began in 1869thus seems possible. It is notknown whether the 1850s population,introduced by shipping,persisted or diedout. B. improvisuswas collected from MontereyBay in 1916,from the Los Angeles/LongBeach area in 1932,and from San Simeon Point and San Diego in 1939.Despite these records from the 1930s, B. improvisus does not appear to be established in southern California. There are other reports from the tropical or subtropicalPacific, though actual collections are few: the Gulf of CaliforniairL 1889, 1941and 1967;the west coast of Mexico in 1960-1968;Colombia in 1854;Ecuador in 18S4,1934, 1963 and 1966;and Peruin 1926.The identificationof someof these populationsas Balanusimprovisus may bearreexamination. B itnprovisusis likely establishedin baysto the north of SanFrancisco Bay, perhapsin somefrom whichit hasnot yet beenreported. It wascollected from VancouverIsland and Willapa Bay in 1955,from the ColumbiaRiver in 1957 on the shell of the crayfishPacifastacus trorvbridgii!, and from CoosBay in 1978.Since World War II, it has alsobeen reported from Japan, and Australia Carlton, 1979a!. In SanFrancisco Bay its physiologyand behavior were investigated by Newman 967! who found that it tolerated dilution to 3 percent seawater,and that, surprisingly,it wasan osmo-conformerwith its bloodremaining nearly isotonic with its environment.It is the only barnaclefound upstreamof CarquinezStrait in the northernpart of theestuary. At Antiochit livesin freshwaterfor ten monthsof the year.A populationwas found in December1962 living on the concretewalls of the Delta Mendota Canal in essentially fresh water, although there is no evidence that barnaclesin the canal reproduce successfully Zullo et al., 1972!.

F.pjneba1iasp,

This unidentified nebaliid was collected on muddy bottom by John Chapman in Aquatic Park Lagoonin Berkeleyin 1992,and we found it commonat Richmond in 1993and Lake Merritt in 1993and 1994.G. Gillingham pers. comm., 1995! reports "Nebalia pugettensis"collected at the Alameda Naval Air Station in the spring of 1993.The prior absenceof reportsof any nebaliidfrom SanFrancisco Bay, and specifically the absenceof a nebaliid from the East Bay shore in the 1960s-1970s, suggeststhat all thesespecimens are an introducednebaliid rather than the native N. pugettensis.Although largely benthicorganisms, nebaliids could easilybe transported by baHastwater in suspendedsediments swept up from the bottom while the ship is baHasting. Introduced Species Page81 hlyadam Acanthomysisaspera li, 1964 Thisplanktonic Japanese mysid was found in the northernpart of the San FranciscoEstuary in 1992and was still present,though not abundantin 1993-94.It wasprobably introduced inballast water T. W. Bowman, in litt. to J.J. Orsi; Orsi, 1994, 1995!.

Acanthomysis sp. An undescribedspecies of Acanthomysis,resembling A. sirtertsis T. W. Bowman,in litt, 23Mar. 1994to J. J. Orisi!, was collectedin SuisunBay in 1992,and was more abundant than the common native opossum shrimp Neomysis mercedis by 1994Q. Orsi, pers. comm., 1995!. Because its morphologyresembles that of westernPacific mysids and is unlikethat of easternPacific species, it is probably nativeto the westernPacific and was transportedto Califorruain ballastwater Orsi, 1994; T. W. Bowman, in litt.!.

Deltamysisholmqttistae Bowman & Orsi, 1992 Deltamysishoimqttistae was first collected and described from the San FranciscoEstuary in 1977.Bowman & Orsi992! reportthat it hasbeen collected everyyear since, ranging from one specimen in 1984to 39in 1987.Most were collectedfrom to theDelta, with onetaken in SanPablo Bay during thehigh spring outflow of 1983.They were found mainly in salinitiesof '1-2ppt at theupstream edge of theentrapment zone, but rangedfrom 0-19 ppt. Deltamysisis in the tribe Heteromysinialong with mysidsthat are commensalor epibenthic,or that swimamong sea grass plants, and this could accountfor the small numbersof Deltamysiscollected in openwater trawls. That Deltanrysiswas not collected until 1977despite sampling for rnysidssince 1963, and thatit hasbeen collected regularly if sparselysince 1977, strongly suggests that it is introduced,probably in ballastwater, There are no known mysid species that closely resembleit Bowman& Orsi,1992!, but targetedsearches in westernPacific estuaries thatare the originof otherrecent zooplankton introductions could be fruitful.

sumac~ NippoIeucort hirtttmertsis Gamo, 1967!

SYNONYMS: Hemilettcort hin ttmertsis Thiscumacean is nativeto Japanand was introduced to thenortheast Pacific in ballastwater. The Califorrua Department of WaterResources has collected it in Introduced Species Page B2

SanFrancisco Bay in the westernDelta and Grizzly Bay since1986, and at densitiesof hundredsor thousands/m> with a maximumof over 12,000/rn! it was one of the three numerically dominant speciesin theseareas from 1988to 1990.It has also been collected at Pt. Pinole in San Pablo Bay since sampling started there in 1991 Hymansonet al., 1994;DWR, 1995!.We collectedit from the ,San Pablo Bayand the South Bay in 1993-94.It was collected in Oregonfrom CoosBay in 1979, from the UmpquaRiver in 1983,from YaquinaBay in 1988,and from the Columbia River 0. Chapman, pers. comm.; JTC, pers. obs.!.

IliQQKLL Dynoidesdentisinrrs Shen, 1929 Wecollected this isopod, known previously from Japan and Korea, in fouling from the Oakland Estuaryin 1977and from the RichmondMarina in 1994.It was probablytransported in shipfouling or ballastwater.

Errrylanaarcrrata Hale, 1925!

SYNONYMS: Cirolana arcuata Cirolana concinna Hale Cirolana robrrsta Menzies, 1962 Errrylarraarcuata was collected in SanFrancisco Bay on eight occasions in 1978 and1979 from the cooling water intake screen of a powerplant at Rodeoin San PabloBay, including brooding females and juveniles Bowman et al.,1981!. We collectedit from floating docks on in theOakland Estuary in 1993 and 1994, Errrylanaarcrrata was first described from Australia, but has not been reported fromthere since It wasreported from New Zealand, where it is widespreadand abundant,in 1961,and from severaldistant sites in Chile asCirolana concinna and C,robusta! since 1962. It is not known which of theseis its native region. It was likelyintroduced to SanFrancisco Bay in foulingor ballastwater Bowmanet al., 1981!. lais californica Richardson, 1904! laiscalifornica is a smallcommensal isopod that is generallyfound clinging to theventral surface of theintroduced burrowing isopod Sphaerorna quoyanrrrrr. It wasdescribed from San Francisco Bay in 1904,but was presumably introduced along with Sphaeromain ship fouling by 1893.lais was reported from New Zealand and Australiain 1956.In California,lais has been collected in most of thebays and harborswhere Sphaerorna is found, and from none where Sphaerorrra is absent Introduced Species Page S3

Carlton,1979a!. In 1995we foundit onSphaeroma burrowing in floatingdocks on IsthmusSlough in CoosBay. laisscavenges food from the mouthparts and the burrow walls of its host, and isprotected from predators and adverse conditions both by Sphaeroma's burrow and S phaeroma'shabitof curling into a ballwhen disturbed. lais is occasionally found on the nativeisopod Grtorimosphaeroma oregorrertsis when the latter live in Sphaeromaburrows. Unlike Sphaeroma, Gnorimosphaeroma will actively remove lais Rotrarnel,1975b!. These commensal relations have been studied by Rotrarnel 972, 1975b!and Schneider976!.

Limnoriaquadripunctata Holthuis, 1949 and Lirrrnoriatripunctata Menzies, 1951

GRIBBLE Limrjoriaare small wood-boring isopods that arewell-known for attacking anddamaging ships' hulls, pilings and other wooden structures in contactwith sea water Kofoid,1921; Hill & Kofoid,1927!. Many species of Limnoriahave been described,some of them morphologicallyvery similar. Somereported distributions arewide to circumglobalor strikinglydisjunct, and undoubtedly complicated by centuriesof transoceanicand interoceanic travel in the hulls of wooden ships. Prior to the 1950s,all Limnoria on the Pacific coast were assignedto Limrtoria /igttorurn,a species which is possiblynative from Alaska to HumboldtCounty, but not knownfrom San Francisco Bay. A Limnoriaspecies was reported from Los Angelesin 187!and San Diego in 1876 Carlton, 1979!. Limrtoria was not mentioned in 1855,1863 and 1869 reports on shipwormdamage to pilingsin SanFrancisco Bay Ayres& Trask,1855; Harris & Ayres,1863; Neily, 1927!, but was described as "recentlyappeared" on the SanFrancisco waterfront probablyL. quadripunctata, basedon currentdistribution and thermalrequirements! in 1873 Arnold, 1873!,and reportedfrom the Oakland Estuary probably L. tripurrctata!in 1875 Merritt, 1875!. L. quadrjpunctatahas since been collected from numerousembayrnents from La Jolfa to Humboldt Bay,and L. tripunctatafrom Port Huenemein VenturaCounty, Californiato Mexico,with the tripunctatapopulation in the warm-watermargins of SanFrancisco Bay remainingas an isolatednorthern outpost Carlton,1979!. Carlton 979! hasargued that the Limnoriareported from northernOregon, Washington and BritishColumbia as tripunctata Quayle, 1964b! is probablya differentspecies. Thenative regions of L. quadripurtctataand tripurtctataare not known.They weretransported to thePacific Coast in thehulls of woodenships, and dispersed alongthe coast in ships'hulls, log booms,log shipmentsor driftingwood.

Paranthura sp. In 1993we collecteda speciesof Parartthurathat had not previouslybeer reportedfrom San Francisco Bay g, Chapman,pers. comm., 1995!. The isopod w» verycommon in foulingon floatingdocks from theSouth Bay and Central Bay and PageB4 Introduced Species northto Richmondin 1993and 1994, but was not observed in 1995.Irutial examinationsuggests strong affinities with western Pacific species Q.Chapman, pers. comm.,1995!, Introduction has likely been by ship fouling or ballast water.

Sphaeromaquoyanum Milne-Edwards, 1840 SYNONYMS;Sphaeroma pentodon Richardson, 1904 Sphaeromais a burrowing, filter-feeding isopod native to NewZealand, Tasmaniaand Australia, and was collected in SanFrancisco Bay in 1893,probably havingbeen introduced via ship fouling. It spread widely in Californiaand was collectedin HumboldtBay, Tomales Bay, Los Angeles-Long Beach Harbors, and San DiegoBay in thelate 1920s and early 1930s, and in severalintervening bays and in SanQuintin Bay, Baja California since the 1950s Carlton, 1979a!. In 1995we found it burrowingin floatingdocks on Isthmus Slough in CoosBay. Sphaeromaisreported as common and frequently abundant throughout San FranciscoBay at leastas far upstreamas Antioch Kofoid & Miller,1927!, though we did not find it on docksin the seawardportion of theCentral Bay. It burrowsinto all typesof softsubstrate, including clay, peat, mud, and soft or decaying wood, andwood that hasbeen bored by shipwormsand gribbles.It is frequently found riddlingthe styrofoamfloats underneath docks, and is sometimesabundant in fouling accumulations.Carlton 979a,b! suggested that Sphaeroma'sburrowing couldbe responsiblefor substantialerosion of intertidalsediments, which he estimatedas possibly amounting to theloss of tensor scoresof metersof land along manykilometers of shorelinein SanFrancisco Bay. However, no measurementsof Sphaeroma'stopographic impact have ever been made. Studies of its biologyin central California include those of Harrows 919!, Rotramel 972, 1975a,b!and Schnei der 976!.

Synidotea laevidorsalis Miers, 1881!

SYNONYMS:Synidofea laticauda Benedict, 1897 Synidotealaticauda was described from San Francisco Bay oyster beds in 1897. It is commonlyfound in theBay on thebottom and on buoys,floating docks and pilings amongmasses of the introducedIndo-Pacific hydroid Garveia franciscana uponwhich it is thoughtto feed!and the introducedAtlantic bryozoan Conopeum tenuissimum Carlton, 1979a!. S. laticaudawas long consideredto be a native species restrictedto the Bay,and its distribution and that of two other northernPacific Synidoteaspecies was explainedby a modelinvolving Pleistoceneclimate changes, range constrictionsand expansions,isolation and evolution, and competition Miller, 1968;Menzies & Miller, 1972!. Chapman& Carlton 991, 1994!identified S, Iaticaudafrom Willapa Bay and synonymizedS. laticaudawith S. marplafensisand S. brunneaof easternSouth IntroducedSpeci<5 Page85

America whereit wasfirst collected in 1918!under the Asianname S. laevidorsalis. Theyconcluded that the species is native to Asia and was transported to San FranciscoBay among hydroids and bryozoans fouling the hulls of ships probably fromChina!, transported by similarmeans to SouthAmerica probably from San FranciscoBay!, and transported to WillapaBay either from San Francisco in ship foulingor withcargoes of thenative oyster Ostrea conchaphfla! or Asia in ship fouling or withcargoes of theJapanese oyster Crassostrea gigas!. Synidotealaevidorsalis is reported to be a commonbenthic organism from thefar SouthBay to Pittsburgin SuisunBay, and less common in theCentral Bay andupstream to Antioch.It wascollected in boththe shallows and the channels,at concentrationstypically up to 100/m2 Hopkins,1986; Markrnann, 1986!. In 1993-95 we foundit commonto abundanton floatingdocks and buoysin San PabloBay and theNapa River, It is saidto be an important food of diving ducks and fish Painter, ].966!.

~aiba Si nel 0 bussp.

This abundant tanaidwas first reportedfrom SanFrancisco Bay by Miller 968, asTanais sp.! based upon materialcollected from a navigationbuoy in San PabloBay in 1943,and laterby Miller 975, asTanais sp., cf. T. Mnis!and Carlton 979a, as Tanaissp., cf. T. vanis,and 1979b,as Tartais sp.!, based upon specimens collected in Lake Merritt, Oakland by Carlton commencingin 1963.Carlton 979a! further reportedspecimens collected in 1965from CorteMadera Creek in Marin County from the stomachof the native sculpin Cottusasper. Theonly other recordsappear to be from Humboldt Bay asTartais sp.; S. Lamed,pers. cornrn., 1989!, and from several estuaries in BritishColumbia as Tnnaisstanfordi; Levings k Rafi, 1978!where it occurredin densitiesup to 17,400 per0.25 square meter in muddy sedimentsover a salinityrange of 3.7to 22.7ppt, and in 7 out of 21 planktontow stations.Levings & Rafi 978! notedthat therewere no previous records of stanfordi from the west coastof North America. Sieg980! and Sieg& Winn981! consideredthe report and figure of Miller 968! to belongto Sinelobusstanfordi Richardson,1901!. They further synonymizedthe earlier report of Menziesk Miller954! of a "Tanaissp." from centralCalifornia with Sinelobusstanfordi, but thatrecord is basedon material collectedon theouter rockyshore Light, 1941,p. 92!and no doubtrefers to a different species. Sineiobusstanfordr' was described from the GalapagosIslands, and has subsequentlybeen reported from "Arctic cold, north Pacifictemperate, southern temperatewaters, tropical warm Pacific, tropical Indo-West Pacific, tropical Indian, and tropicalwarm Atlantic"waters Sieg,1986!. Localities include Brazil, West Indies,the Mediterranean,Senegal, South Africa, Tuamotu Archipelago, and Hawaii, as well as the borealKurile Islands,and Holdich& Jones983! added England,Reported habitats include fresh, brackish, marine and hypersaline v ater. Introd" eed S pecies Page86

Gi enthis bro ad distribution, it is probable that a speciescomplex isinvolved includingtaxa which have been dispersed synanthropicaiiy!, andwe are hesitant to applythe name of a warmtropical tanaid described f om the Galapagos hinds to theSan Francisco Bay population. Though this population was earlier identified as Tarial'svarils Miller, 1940. this is analgal-dwellmg species of Hawaiian fring g coral reefs Carlton, 1979a! and thus also not likely to be the species in gm FranciscoBay. Thissmall cn stacean is widespreadthroughout the estuarine margin of the Bay,and s beencollected upstream at leastas far as Chipps I imd piegfriedet a 1980!.It is replacedby thecryptogenic and more marine tanaid L tocgeliadubia in themiddle and outer bay regions.Iaddition to thebent}uc habitat noted by Levings & Rafi978! in BritishColumbia, in SanFrancisco Bay it occurscorrunonly in fouling communitiesamong masses of the introducedtubeworrn Ficopomafus an iumb«ingalong in intertwinedmats of thegreen algae Uiva and Cladophora,often in associationwith the introduced amphipodsMelita and Corophium,It occurs commonlyin habitatswhere all other peracaridsare introducedor cryptogeruc. W'eregard Sirielobiessp. of San FranciscoBay as introduced;the origin of these populations remains unknown, Introductionwas possiblyvia ship fouling or ballast water,

Ampelisca abdifa Mills, 1964

SYNONYMS:Ampelisca milleri of San FranciscoBay authors, not of Barnard, 1954 Ampelisa milleri of' Dickinson, 1982 Dillon Beach record!

Ampeliscaabdita is native to northwest Atlantic from Maine to the eastern Gulf of Mexico.It wascollected on the Pacificcoast from SanFrancisco Bay in 1954, fromTomales Bay in 1969,and from BolinasLagoon in 1971 Carlton, 1.979a, p. 64$; Chapman, 1988!, On the Aiiantic coast,Ampelisca abdita often occursin oyster beds and forms extensive mats of silt tubes which provides stable substrate for numerous other organisms.As A. abdita is a small amphipod,Chapman 988! arguesthat it could have been present in the Bay for a long time before the 1950sand not been noticed dueto a combinationof the urideveloped taxonomy of smallarnphipods up to that time and the use of sieves with mesh openings of at least 1 rnm which retain few A. abdita!in early surveys.Thus it could havearrived with shipmentsof Atlantic oysters in the late nineteenth or early twentieth century. SinceA. abdita sometimes migrates mto the water colurnri Chapman, 1988!,it could also have arrived later in ballast water. Ampeliscaabdifa is now a verycommon and abundant benthic organism in SanFrancisco Bay, recorded at virtuallyall sitessurveyed from far SouthBay to CarquinezStrait, with concentrationscommonly of 1,000-50,000/squaremeter. It is lessabundant in westernpart of Central Bay,and lesscommon and less abundantin Suisun Bay, although collected upstream to Antioch Hopkins. 1986!. Its abundance 1ntroduced Species page87 varies annually, peaking around October, although Ampeljscamay be e»minated from largeregions of the Bayby floods,either becauseof salinity changesor . When abundant, it may interfere with the recruitment of Macoma petalum Nichols t|r Thompson,1985a!.

Ampithoe valida Smith, 1873

Ampithoevalida is native ta the northwest Atlantic from New Hampshire to ChesapeakeBay Bousfield,1973!. It hasbeen collected on the centralCalifornia coast from San Franciscoand Tomalesbays first records in 1941!,Morro Bay 960!, BodegaHarbor and BolinasLagoon 975! Carlton,1979a, p. 649!,and HuznboldtBay S. Lamed,pers. comm.!. There are singlerecords from Newport Bay in southern California 942!, Coos Bay, Oregon 950! Carlton, 1979a!and severalother records from Oregonto southernBritish Columbiasince the late 1960s Conlan & Bousfield, 1982;Chapman, pers. comm.!. Ampithoe valida builds and lives in tubes on algae and eelgrass,and has been found on oysterbeds on the Atlantic coast.It could havebeen mtroduced to San FranciscoBay with Atlantic oystershipments and remainedundetected for decades, or arrived in hull fouling or ballast water. In 1993-94we collected it at several stations in SanPablo Bay, at Coyote Point in the South Bay, and at Pier 39 m San Francisco.

Caprella mutica Schurin, 1935

SYNONYMS:Caprella acanthogaster of Pacific coast authors e.g., Carlton, 1979a, 1979b!,not of Mayer, 1890 Caprella acanthagasterhumboldtiensis Martin, 1977

SKELETON SHRIMP

This caprellidshrimp, a nativeof the Seaof Japan,has been collected in Humboldt Bay about1973-77!, San Francisco Bay 976-1977!,Kikhorn Slough 978- 1979!and CoosBay, Oregon 983! Martin, 1977;Marelli, 1981;JTC, unpublished!. Marelli 981! concludedthat Martin 977! had incorrectlydescribed this Japanese species*om Humboldt Bay as a new subspeciesof Caprellaacanthogaster which is a speciesdistinct from C. mutica!,It wasreported as comprising40 percent of the caprellidsat Field'sLanding in Humboldt Bay Martin, 1977!and 90percent of the caprellidsin the OaklandEstuary D. Cross,pers. comm., 1977!. Based on its recent dateof discoveryon the Pacificcoast, may havebeen introduced to Humboldt Bay with shipmentsof Japaneseoysters, which occurredfrom 1953 through the 1970s,and secondarilyintroduced to SanFrancisco Bay; or it may have beenintroduced to either or both baysin ballastwater Caprellaspecies have been found to survive transport in ballast tanks; Carlton, 1985,p. 346!. Jntroduced Species PageSH

Chelura terebransPhilippi, 1839

Cheluraterebrans lives in burrows in wood in associationwith wood-boring isopodsin the genusLimnoria, and reportedlyfeeds upon Limnoria'sfecal pellets Kiihne 6zSeeker, 1971!. It has undoubtedly been transported around the world with Limnoria in the hulls of wooden ships. It is reported from the Atlantic on both the American and European coasts,the Mediterranean and Black seas,and froxn French West Africa and South Africa. In the western Pacific it has been collected in Australia, New Zealand and . Its area of origin is unknown. The absenceof Chelurafrom Limnoria-boredwood in San FranciscoBay, MontereyBay and SantaBarbara County wasnoted by the marine piling surveysof the 1920s Kofoid, 1921;Atwood k Johnson,1924; Hill k Kofoid, 1927!,although Carlton 979a! arguesthat due to the patchydistribution of Chelurapopulations it could have been present and overlooked. Chelurawas not recorded from the northeastPacific until 1948at HuntersPoint Naval Shipyard in SanFrancisco Bay USNavy, 1951,p. 185!,followed by collectionsfrom LosAngeles Harbor {1950!and GraysHarbor, Washington 959-1960! Carlton,1979a, p. 650!.

Corophium acherusicumCosta, 1857

Corophiumacherusicum has been reported from baysand harborsm the Atlantic,Pacific and Indian oceans, though which of thesemay be its nativeregion is unknown.On the Pacificcoast it hasbeen collected from numerous bays and harborsranging from British Columbia and possiblyAlaska! to BajaCalifornia. Earlyrecords are from Yaquina Bay, Oregon 905!, SanFrancisco Bay {1912-13 Albatrosssurvey!, PugetSound, Washington 915!, VancouverIsland, British Columbia{1928!, and Newport and Anaheimbays in southernCalifornia {1935-36! Carlton, 1979a,p. 653!. Corophiumacherusicum is a commonfouling organismon floatsand pilings,has been reported from oysters,and reported from ship hullson several occasions references in Carlton,1979a!. It wasprobably introduced to the Pacific Coasteither as ship fouling or possiblyin shipmentsof Atlanticoysters. In SanFrancisco Bay Corophium acherusicum has been collected upstream to Collinsville,and is amongthe most common species in the Departmentof Water Resources'benthic samplesat Carquinez Strait. In 1993-94we collected it at stations in SanPablo Bay and in the PetalumaRiver. It establishedhigh densitiesin Suisun and Honker baysduring the 1977drought Markmann,1986!.

Corophium afienenseChapman, 1988 Corophiumalienense was first collectedin SanFrancisco Bay in 1973and is probablynative to SoutheastAsia, based on its morphologicalsimilarity to other SoutheastAsian Corophium Chapman, 1988!. It wasmost likely introducedto San Page89 Introduced Species FranciscoBay in ballastwater Corophium areknown to migrateinto the water columnat night, and ballast water often contains amphipods; Carlton R Gentler, 1993!,possibly in or onnaval ships returning from Vietnam Carlton, 1979a, as Corophiurnsp.;Chapman, 1988!. It has become abundant in many parts of the Bay fromthe South Bay to the Delta, and is especially abundant onshallow subtidal and intertidalmuddy sand Chapman, 1988!. In 1993-94wecollected it at scattered sites fromTiburon upstream to Rodeo and the Napa River, It wasalso found in abundancein Bodega Harbor in 19920, Chapman,pers. comm.!.

Corophium heferoceratumYu, 1938 Corophiurnheteroceratum wascollected from San Francisco Bay at leastby 1989 Chapman k Cole, 1994! and possibly asearly as 1985 or 1986 Chapman, pers. comm.,1995!, and from Los Angeles Harbor in 1990.Outside of California,the only recordsare the type specimens collected in 1929 from a tidepool in Tangku Tanggu!,China, in the northwestern Yellow Sea. C. heteroceratum isprobably nativeto Asia,as it is morphologicallysimilar to otherAsian species of Coraphium Chapmank Cole, 1994!. In SanFrancisco Bay, Coraphfurn heteroceraturn is found on silty sediments atlow intertidal or subtidaldepths at salinitiesover 15 ppt, frequently co-occurring with theintroduced Atlantic amphipod Ampelisca abdita. It is widespreadand locallyabundant inthe Bay, especially atsalinities >20 ppt and temperatures >16'C, reachingdensities ofup to 9,600/m2, andhas been collected atleast from the northernSouth Bay to northern San Pablo Bay Chapman k Cole, 1994!, with a few recordsfrom Grizzly Bay DWR, 1995!, We tentatively assign a firstdate of collection ofthis amphipod in San Francisco Bayas 1986, based upon the arguments presented byChapman k Cole 994! and upon probable circa-1986 specimens received byJ. Chapmang. Chapman, pers. comm., 1995!, In 1993-94,we collected C heteroceratum at Tiburon and at two stationsin San Pablo Bay. AsCoroplrium heteroceratum hasbeen found exclusively on soft-bottom, not onhard substrates or buoy fouling in SanFrancisco Bay, it is unlikelyto havebeen transportedin ship fouling Chapman & Cole,1994!. Ballast water transport seems likely,as Corophium areknown to migrateinto the water column at night Chapman,1988!, and ballast water often contains demersal plankton benthic organismsthat migrate into the water column!, including amphipods Carlton k Geller, 1993!,

Corophiuminsidiosum Crawford, 1937 Corophiuminsidiosum is a NorthAtlantic species known from both the Europeanand American coasts Bousfield, 1973!, and introduced toboth Chile by 1947!and Hawaii by 1970! Carlton, 1979a, p. 657!.The first Pacific record is a specimentaken from the stomach ofa bird,a greaterscaup, collected atOyster Bay, Washingtonin 1915. In 1931Corophium insidiosum was collected in Lake Merritt IntroducedSpecies Page90 in SanFrancisco Bay, where it wasthought to be a newspecies. It wasfound in four southernCalifornia bays from 1949-1952,in TomalesBay, Monterey Harbor, Bolinas Lagoonand Elkhorn Slough between 1961 and 1977, in theStrait of Georgiain British Columbia in 1975 Carlton, 1979a!,and on a wooden ship in Humboldt Bay, in 1987 Carlton k Hodder, 1995!.It is commonlyfound in fouling, and wasprobably transportedto the northwesternPacific in shipfouling or with shipmentsof Atlantic oysters. Corophiumirtsidiosttm has remainedabundant in Lake Merritt where we collected it in 1993-94,as well as at several sites from the mouth of the Bay upstream to Martinez, at Coyote Point in the South Bay, and at Aquatic Park in Berkeley.

Gammartts daibert Bousfield, 1969

Gammarus daiberi is native to the northwestern Atlantic in estuaries and soundsfrom Delaware and Chesapeakebays to SouthCarolina Bousfield,1973!. In theselocations it attainsits highestdensities in salinitiesof 1-5 ppt, but is found seawardto 15 ppt. It was collectedin the centralDelta in 1983,and since1986 has beenregularly collected in the centraland westernDelta and SuisunBay Hymanson et al., 1994!.In 1993-94we collectedit from in the Delta and from Martinez, It is eatenby young stripedbass Hymansonet al., 1994!. On the Atlantic coast it is describedas mainly pelagic, though also commonly collected on the bottom and in fouling E. L. Bousfield in litt. to W. C. Fields, Jr., 1991!.We considerit to be probablya ballast water introduction, and lesslikely a ship fouling introduction.

Grartdidierellajaponica Stephensen, 1938

This tube-dwellingamphipod is native to Japan. It was collected from San FranciscoBay near Vallejo a.ndin Lake Merritt, Oakland,in 1966,from TomalesBay in 1969,from BolinasLagoon in 1971,from DrakesEstero in 1972-73 Chapman& Dorrnan, 1975;Carlton, 1979a,p. 662! and from Coos Bay, Oregon since 1977QTC, pers. obs.!, lt has been establishedin southern California bays since at least the early 1980sQ. Chapman, pers.comm.!. It is typically found on muddy or mud-sand bottom, sometimes in oyster beds, and sometimesin fouling. It was introduced with commercial oyster transplants from Japan,with ship fouling or in ballast water. Grandidierellajaponica has beencollected from all parts of San FranciscoBay, from the SouthBay near Redwood City upstreamto Antioch.It is oneof the most commonbenthic species in San PabloBay and CarquinezStrait Chapman& Dorrnan,1975; Nichols k Thompson, 1985a;Markmann, 1986!.In 1993-94we collectedit from severalstations in SanPablo Bay upstreamto Martinez,Napa and Petaluma,from CoyotePoint in the SouthBay, and from l.ake Merritt and Berkeley's Aquatic Park in the EastBay. Introduced Species Page 91

In BolinasLagoon it has been recorded from the stomachs ofleast and westernsandpipers, dunlin, black-bellied plover and willet Page& Stenzel,1975; Stenzelet al., 1976!.

Jassamarmorata Holmes, 1903 SYNONYM:Jassafalcata of Pacific coast authors in referenceto bay or estuary populations,not of Montagu,1808 see Conlan, 1990!. ThisAtlantic fouling arnphipod is nowwidely spread on both sides of the NorthAtlantic, in the Mediterraneanand on the Pacificcoast of North America, andreported from other locations aswell. Carlton 979a! predicted thatthe bay and harborpopulations of so-called " falcata" represented "an introduced taxon." Conlan in litt.,7 Oct.1986 to JTC and in litt.,5 Aug.1986 to J.W. Chapman! noted thatbased on her systematic revision of the genus Jassa and her field work on the Pacificcoast, she "found the distribution of [Jassa] tobe as predicted by" Carlton 979a!:endemic species occurred on the exposed outer coast, and the Atlantic Jassa marmoratato be harbor-restricted.Conlan in litt.; alsosee Conlan,1988! statesthat Jassamarmorafa is "the mostrecently derived of all speciesof Jassa,"that it originatedin theNorth Atlantic and specifically onthe "Atlantic North American coast,"and thatit is introducedto Europe,the Mediterranean, the Pacific Ocean China,Japan, USSR, Chile, and Pacific North America!, the South Atlantic Brazil, WestAfrica, andSouth Africa!, the Indian Ocean Zanzibar!and Australia and New Zealand.It ranges in theWestern Atlantic from Newfoundland toTexas and Cuba. On thePacific coast I, rrtarmoratahas been collected from Alaska onelocality, Point Slocum!and BritishColumbia VictoriaHarbor, Bamfield! and thenfrom CoosBay, Oregon to Bahiade Los Angeles, Baja California Conlan, 1990!. Additionalharbor records cited by Carlton979a, pp 667-668!may also include Jassa ma rmorata. Theearliest San Francisco Bay record appears to be material collected in the OaklandEstuary in 1977 Carlton, 1979a!. That Jassa marrnorata isa 20thcentury ratherthan a 19thcentury introduction is suggested by the relativelylate reports of estuarinemembers of theJassa falcata group from the eastern Pacific in 1941from Esterode San Antonio,75 km north of SanFrancisco, and in 1942from Magdalena Bay,Baja California; Carlton, 1979a!. Both Carlton 979a! and Conlan 988! have declinedto acceptBarnard's 969! proposalthat "Podoceruscalifornicus," described by Boeck872! from California,is "Jassafalcata." Jassamarmorata occurs in foulingcommunities and on ship hulls Bousfield, 1973!and with oysters Wells, 1961, as ""!. It has also been collected from theballast tanks of a cargoship arriving m CoosBay, Oregon after a 15day trip from Japan,in water thathad been taken aboard in Kobeon the Mand Seaof Japan specimensidentified by K. Conlan,in litt, 4 Aug.1988!. Lack of early reports of this nowlocally commonspecies suggests ship foulingor ballast water as the primary mechanism of transport. introducedSpecies Page 92

Leucofhoe sp.

We regard the endocornmensalamphipod found inside the introduced tunicatesCiona and Ascidiain SanFrancisco Bay as an introducedspecies. It may belongto the speciescomplex bearing the names Leucothoe spinicarpa Abildgaard, 1789!and Leucothoe alata Barnard, 1959 J. Chapman, pers. comm., 1995!. Nagata's 965! illustrations of "Leucothoealata" from Japan,which may not be the sameas Barnard's original material of this species,appear close to if not identical to San FranciscoBay specimens J. Chapman, pers, comm., 1995!. In 1993-94we collectedthis amphipodin Cionaand Ascidia at CoyotePoint in theSouth Bay and Coast Guard Island in theOakland Estuary. It waslikely introducedinside a tunicatetransported either in ship foulingor possiblywith oyster shipments. While the first actual collection record that we have found is materialcollected in 1977from the OaklandEstuary, this leucothoidmay have been present in the northeastern Pacific since the introduction of Ciona which was collectedin SanDiego Bay in 1897and in SanFrancisco Bay in 1932!.

Melita nitida Smith, 1873 Melitanitida is nativeto thenorthwestern Atlantic, ranging from the Gulf of St.Lawrence to theYucatan Peninsula. It was first collected from San Francisco Bay in 1938,from HoweSound in BritishColumbia in 1973,from Elkhorn Slough in 1975,and in Oregonfrom Yaquina, Coos and Alsea bays in 1986-87 Carlton, 1979a, p. 672; Chapman, 1988!. On the Pacificcoast Meh'ta nitida is commonlyfound in fouling,under intertidal rocks and debris,and in Enteromorphaor diatom mats on mudflats, in salinities from 0 to 25 ppt Chapman, 1988!.On the Atlantic coast it has been reportedfrom similar habitatsas well as from oysterbeds. Melita nitjdacould have beentransported to thePacific coast in shipfouling, in transcontinentalshipments of Atlantic oysters, or possibly in solid ballast or ballast water. It could have been transportedbetween bays in foulingor ballast,or with shipmentsof oystersor the introducedsoft-shell clam Mya arenaria. In SanFrancisco Bay it hasbeen collected fromLake Merritt, Point Richmond, Rodeo, Petaluma, Martinez and Grizzly Bay, andfrom Collinsville on theSacramento River at densitiesof up to 355/rnid Chapraa,1988; DWR, 1995; and 1993-94 survey!.

Melita sp.

In 1993we collectedan amphipodin thegenus Melita, distinct from Melisma nitida,that had not been previously reported from San Francisco Bay 0. Chapman, pers.comm., 1995!. While its originis unknown,introduction via shipfouling or ballast water are the most probable mechanisms. 1ntroducedS pecies Page 93

Paradexamine sp. In 1993-94we collectedan amphipod in thegenus Paradexam'me thathad not beenpreviously reported from San Francisco Bay0. Chapman, pers. comm., 1995!. Introductionwas probably by ship fouling or ballast water.

Parapleustesderzhavini Gurjanova, 1938! SYNONYMS:¹opleustes derzhavini Parapleusfesderzhavini makik' rBarnard, 1970 Parapleustesderzhavi»i is known as a rarespecies from among intertidal and subtidalalgae in thewestern Pacific inJapan and Russia. It has also been collected fromHawaii, where it isprobably an introduction. In the northeastern Pacific it was collectedfrom San Francisco Bay in 1904 discovered among USNM campanularid hydroidspecimens byJ. W, Chapman!, Tomales Bayin 1970,Coos Bay in 1986and YaquinaBay in 1987 Carlton, 1979a; Chapman, 1988!, InSan Francisco Bayit has beencollected from San Mateo Point in the SouthBay to GrizzlyBay, and upstream asfar as Collinsville on theSacramento River in the1977 drought Chapman, 1988; DWR,1995!. It wasprobably introduced in ship fouling. On thePacific coast P. derzhavinihas been found at salinitiesof 6 to32 ppt., abundanton hydroids in fouling but rare on algae. Specimens from brackish water on the Pacificcoast identified as Parapleustes pugettensis may in factbe P. derzha vi »i.

S te»othoe valida Dana, 1852 Ste»othoevalida has a widespread,mainly tropical distribution. It hasbeen reportedfrom only four Pacific coast embayments: SanFrancisco Bay first collected in 1941!,Los Angeles Harbor 950-51!, Newport Bay 951! and Bahia de San Quintin,Baja California 960-61! Carlton, 1979a, p. 677!. It iscommonly found amongfouling, especially inhydroids, and was probably introduced either in ship foulingor in ballastwater. In 1993-94we collected Stenothoe valida, identified byJ. W. Chapman,at sitesall aroundthe CentralBay.

Tra»sorchestioerrigrnatica Bousfield 8z Carlton, 1967!

SHORE HOPPER

SYNONYMS: Orchesfia enigmatica Introduced Species Page94

This beach-dwelling amphipod was first collected in Lake Merritt, Oakland a brackish lagoon! by JTC in 1962,and is known only from the Lake and rarely! from the channel connecting to the Oakland Estuary. A closely related or possibly identical! species,Transorchestia chilensis, is reported from Chile and New Zealand Like other talitrid amphipods,T. enigmttticacannot survive long immersionin water, and its likeliest meansof introduction is in solid ballast i. e. sand, stones and detritus from beaches!that was in commonuse by woodencargo ships Up until the 1920s.There was substantial trade between California ports and Peru and Chile from thelast half of the 19thcentury to the 1920s,with shipsgoing south carrying grain or lumber and returning in ballast Carlton, 1979a!.

P~ai~od Carcinus maenas Linnaeus, 1758!

GREEN CRAB

This common Europeanshorecrab was introduced to the Atlantic coast of NorthAmerica by 1817 Say, 1817!, to southernAustralia by 1900 Fulton 5 Grant, 1900!and to SouthAfrica by 1983 Le Rouxet al., 1990!.It wasfirst collectedin Californiain the EsteroAmericano, Solano County, in 1989,and in SanFrancisco Bayby a baittrapper in RedwoodShores Lagoon, San Mateo County in thesurnrner of 1989or 1990.It wasprobably transported toSan Francisco Bay in ballastwater, althoughother possible mechanisms include shipment in algae used to pack shipmentsof live New England bait worms Nereis virens and Glycera dibranchiata}or lobsters Homarus americanus!, release as discardedresearch material,or transportin a ship'sseawater pipe system Cohen et al., 1995;Carlton & Cohen, 1995!. In SanFrancisco Bay it hasbeen collected from the South Bay from south of theDumbarton Bridge to Beniciain theCarcluinez Strait, where it is found intertidallyand subtidally to10 meters deep, and in lagoonsaround the Bay. It is commonlycaught in trapsset for baitfish gobiesand cottids!, sornetirnes with hundredsof crabs filling each trap, and in shrimpnets. In 1993it wascollected from DrakesEstero, Tomales Bay and Bodega Harbor Grosholz k Ruiz, 1995!, in 1994 fromElkhom Slough T, Grosholz, pers, comm., 1994!, and in 1995from Humboldt Bay T, Miller, pers.comm., 1995!. Carcinustolerates salinities from 4-52 ppt and temperatures down to around 0 C,and can reproduce attemperatures upto around 18-26'C. In favorable conditions,females can up to 185,000 eggs at a time.Invarious parts of the worldit hasbecome common invirtually all types of protected andsemiprotected marineand estuarine habitats, including habitats with mud, sand or rock substrates, eelgrassbedsand cordgrass marshes. Itswide environmental tolerances suggest that onthe Pacific coast it could eventually range from Baja California toAlaska Cohen et al 1995;Carlton & Cohen,1995!. Introduced Species Page95

In field observationsor laboratory experiments,Carcinus has been seento eat an enormousvariety of preyitems, including organisms from at least104 families and158 genera in 5 plantand protist and 14 animal phyla. In analysesof stomach contents,dominant prey at differentlocations have included mussels, clams, snails, polychaetes,crabs, isopods, barnacles andalgae Cohen etaL, 1995!. In California, Carcirruswas observed to significantlyreduce the density of thesmall clams Nufricuia Transennella ! spp., the cumacean Cumeila vulgaris, and the amphipod Corophiumsp. Grosholz k Ruiz, 1995!, and in thelab also consumed themussel Mytilussp., the Asian clams Potamocorbula amurensis and Venerupis philippinarurn,andthe native crabs Hemigrapsus oregorrensis andCancer magister Dungenesscrab! at up to its own size Cohen et al., 1995; Grosholz 8zRuiz, 1995!. Carcinusis fishedcommercially for food and bait in Europe,though its relativelysmall size has prevented its enteringthe commercial market in the UnitedStates. Through its predatory activities, it is generallycredited with the destruction of soft-shellclam fisheriesin New Englandand Canadain the 1950s, wherecontrol effortshave included fencing, trapping and poisoning, with varying success Cohen et al,, 1995!.

Eriocheir sinensis H. Milne-Edwards, 1854

CHINESE MITTEN CRAB Chinesemitten crabsare native to Koreaand China from the Yellow Sea to southof Shanghai.They spend most of theirlives in the rivers and migrate to the estuariesto reproduce.Most authorities have recognized four species ofmitten crabs,including Eriocheir sinensis and E. japorricus which are distinguished byclear andconsistent morphological differences Sakai, 1939; Dai & Yang,1991!. Recently 1i et al.993! foundsmall genetic distances between these two forms suggestive ofa singlespecies, but confirmed the existence ofmorphological distinctions which theydescribed asecophenotypic, although the differences appear tobe more simply explainedasthe expression ofgenetically different populations and their hybrids!. Dai993! andChan et al. 995!have proposed other modifications to the arrangementofspecies within the genus. In lightof this unstable taxonomy, we continue to treat the Chinesemitten crab,E. sirtensis,as a distinctspecies. A Chinesemitten crabwas collectedin the Aller River, Germanyin 1912, generallypresumed tohave been introduced inballast water Panning, 1939!. Mitten crabsspread through the Netherlands andBelgium tonorthern France by 1930 Hoestland,1948!, eventually reaching the west coast of France and, via the Garonne Riverand the Canaldu Midi, the Mediterraneancoast by 1959Pioestland, 1959; Zibrowius,1991!. They became phenomenally abundant inGermany in the mid- 1930s,v'ith massesofcrabs migrating up the main rivers, piling up against , climbingspillways and swarming over the banks onto shore, sometimes wandering ontocity streets and entering houses. Government authorities operated barrel and pit trapsthat caught tens of millions ofcrabs each year in order to prevent damage to banksand the crabs dig burrows over half a meterdeep in mudbanks! and IntrodateedSpecies Page96 reduce interference with trap and net fisheries Panning, 1939!.A "plague o f mitte~ crabs" was similarly rePorted from the Netherlands in 1981. Ingle, 1986!. Hundredsof adult mitten crabshave been collected along the shoresaf the Baltic Sea,but as the Baltic'ssalt contentis too low for successfulspawning these are generallythought to be individuals transportedby ship from the North Sea Haahtela, 1963;Rasmussen, 1987!. Occasional mitten crabs, including a few ovigerous females, have been collected in England since 1976,though it is unclear whether breeding populations are establishedthere Ingle, 1976!. A Chinese mitten crab was collected in the North American Great Lakes in 1965 and nine or ten additional adult crabs were collected between 1973 and 1994, all but one of which were taken from western Lake Erie Nepszy & Leach, 1973;J. Leach, pers. comm.!. As in the Baltic, the Great Lakes are too fresh for mitten crabs to spawn, and eachindividual is thought to have arrived as a larva or juvenile in ballast water from Europe. A single adult mitten crab was collected from the Mississippi River delta in Louisiana in 1987,with none reported since Howarth, 1989;D. Felder, pers. comm.!. In November, 1994a crab caught in a shrimp net in the southern end of San FranciscoBay was identified as Zriocheirsinerisis by Robert Van Syoc of the California Academy of Sciences.Shrimp trawlers report that they have occasionally caught such crabs, many of them carrying eggs,in the South Bay since 1992and in San Pablo Bay since the summer of 1994.Of 75 crabs collected from San Francisco Bay, 24 were female, and all but 5 of thesewere carrying eggs.Several ovigerous females collected in the winter of 1994-95were maintained in aquaria by the Marine ScienceInstitute of Redwood City, California, and hatched active zoeaeby the first week of February. In 1995Katie Halat found juvenile mitten crabs to be common in burrows in the upper parts of sloughs at the southern end of the South Bay. Mitten crabs could either have arrived in San FranciscoBay in ballast water from Asia or Europe, or been intentionally planted in the watershed as a food resource. In 1978Dustin Chivers of the California Academy of Sciencesnoted that live mitten crabscould be importedinto Californiafrom firms in Hong Kong and Macao. In 1986the California Department of Fish and Game found live mitten crabs, bound with twine, offered for sale in Asian food markets in San Francisco and Los Angelesat pricesof $27.50to $32.00per kilogram.Although the importing of live mitten crabswas bannedby the Californiagovernment in 1987and the United States governmentin 1989,the high price they commandhas encouragedcontinuing efforts to import them through official or unofficial channels.On 11 occasionssince 1989,U. S. Fish and Wildlife inspectorsintercepted batchesof 10-28mitten crabs hand-carried by travelers from Asia disembarking at the San FranciscoAirport during the winter H. Roche,pers, comm.!, and crabs have been intercepted at Los Angelesand Seattleas well M. Osborneand M. Williams,pers. comm.!. In 1994an Asian businessmanlobbied the Californialegislature for permissionto import and raise mitten crabsin California T. Gosliner,pers. comm., 19'94!- With its establishmentin SanFrancisco Bay, the mitten crab is one of the few catadomousorganisms living in freshwater and breedingm salt! in North America.Studies on thesecrabs in Asia and Europeindicate that they hve in burrows dug in river banksor in Asia! in rice paddiesin coastalareas. Some Page97 Introduced Species migratefarupstream, andare recorded fromthe Changjiang Yangtze! Riverover 1,250kmfrom the sea, Inthe late fall and winter adult crabs -2years old in China G.Li, pers. comm., 1995!; 3-5years old in Germany Panning, 1939!!migrate to coastalwaters where they mate, spawn and die. Each female produces from 250,00p to1 million eggs, which hatch inlate spring orearly summer. Thelarvae develop throughfiveincreasingly stenohaline andeuhaline zoeaeand a moreeuryhaline andmesohaline megalopa. Afterthe final larval molt the juvenile crab settles tothe bottomandbegins itsmigration upstream Panning, 1939;Ingle, 1986; Anger, 1991!. Theban on importing live mitten crabs was enacted due to concern over potentialdamage fromits burrows tolevees orrice fields inthe Central Valley, and becausethecrab isa secondintermediate hostof a humanparasite, theoriental lung flukeparagonimus tvesfermanii. ArmandKuris and Mark Torchin ofU. C. Santa Barbarafound noparasites ofany kind in 25 mitten crabs from San Francisco Bay A. Kuris,pers. comm., 1995!. However, sincesuitable firstintermediate snailhosts are presentinCalifornia oradjacent states T. Gosliner, pers.comm.!, establishment of thefluke ispossible, which could lead to infections ofhumans, ormore likely, other mammals,Thepotential ecosystem impacts oflarge numbers ofriver crabs, where none now exist, are unknown.

Orconectesvirilis Hagen, 1871!

VIRILE CRAYFISH

SYNONYMS; Cambarus virilis Thiscrayfish isnative toIndiana, and other midwestern states.It was introducedinto California waters atChico in Butte County between 1939 and !941, fromcrayfish that were being held in ponds foruse as laboratory specimens atChico StateCollege. It has since been reported atthe edges ofthe Delta in thelower CosumnesRiver, in and in drainageand irrigation ditches inYolo County,and further north in Butte and Colusa counties where it digs burrows in ricefields and eats rice shoots and is considered a pest by farmers Riegel, 1959; Herbold et al,, !992!. TheU. S.Fish and Wildlife Service proposed listing the native Shasta crayfishPacifasctacus fortisas an endangered speciesbecause ithad been extirpated fromhalf its range between 1978 and !987, in large part due to competition from Orconectesvirilis and another introduced crayfish, p. lertiusculus, for food and space Anon., 1987!.

Pacijnstacusleniusculus Dana, 1852!

SIGNAL CRAYFISH

SYNONYMS; Astacus leniusculus tnrrartuced Specres Page98

It is unclearwhen the signal crayfish Pacifastacus leniusculus, native to Oregon,Washington and British Columbia, was first introduced toCalifornia. Osborne977! statedthat it was introducedto LakeTahoe in the 19thcerttury as foragefor . Kimsey et al. 982; repeated by Herbold& Moyle,1989, and Herbold et al., 1992!reported that it was found in SanFrancisco County in 1898. Riegel959!, however, speaking about the introduction of thisspecies to California, reportedthat in 1912signal crayfish from the Columbia River "were shipped in largebatches to the BrookdaleHatchery of theCalifornia Fish and Garne Commissionin Santa Cruz County [in order] to determinetheir depredatory effects uponyoung . Later, many were released into the SanLorenzo River near Santa Cruz,and about 200 were shipped to NevadaCounty, California, and released in a privatepond on the ShebleyRanch between Colfax and Grass Valley. They were thriving18 years later," Bonnot 930! reportedit asimported "in timespast for culinary purposesand as biologicalmaterial." Signalcrayfish are now widely distributed throughoutthe Delta and Bay Area and centralCalifornia, north to SiskiyouCounty and southto MontereyCounty Riegel,1959; Hazel & Kelley,1966!. They are the main crayfishtaken from the Delta, wherea commercialharvest began in 1970with a catchof 50 tonsand produced annual landings of 250 tons by the 1980s Osborne,1977; Herbold & Moyle, 1989!. Commonly found in streams,large rivers,lakes and sometimesmuddy sloughs, Riegel959! reportedit collectedon one occasionfrom dilute brackish water, and Kimseyet al. 982! reportedthat it toleratessalinities up to 17 ppt. Pacrfastacuslerriusculus may have contributedto the extinctionof the native sooty crayfish, Pacifrrstacusnigrescerrs, which in the 19th centuryhad been abundant in creeksaround San Francisco Bay Riegel,1959; Kimsey et al., 1982!.In 1987the U. S. Fishand WildlifeService proposed listing the nativeShasta crayfish Pacifasctacus fortisas an endangered species because it had been extirpated from half its range between1978 and 1987,in large part due to competition from P. lerriusculusand anotherintroduced crayfish, Orconectes virilis, for foodand space Anon., 1987!. Pacifastacu:leniusculus has also beenintroduced to northern Europe,with populations establishedin Sweden introducedfrom Lake Tahoein 1969;Osborne, 1977!,Finland, Lithuania and Poland McGriff, 1983!.In Swedenthe introductionof P. !erriuscrrlusand a North Americancrayfish fungus have been described as the main causeof the decimationof the noblecrayfish Astacus astacus Oansson, 1994!.

Palaerrrorrrrracrodactylus Rathbun, 1902

ORIENTAL SHRIMP, KOREAN SHRIMP, GRASSSHRIMP

This shrimp is native to Korea, Japanand northern China and was first collectedin SanFrancisco Bay in 1957,in LosAngeles Harbor in 1962,in Santa MonicaBay in the1970s, in CoosBay in 1987,and in HumboldtBay in 1995 Ne»man, 1963; Carlton, 1979a, p 687;T. Miller,pers. comm., 1995!. It is distributed » idelythroughout San Francisco Bay and upstream into the Delta, especially in dry Introduced Species Page99 years,and has been collected inthe Delta-Mendota Canal. It is frequently abundant inbrackish lagoons such as Lake Merritt in Oakland and Aquatic Park in Berkeley Carlton,1979a!, In 1993-94we collected it from among the fouling on docks at severalsites in theBay and upstream inthe Napa River to John F. KennedyPark andin the PetalumaRiver to the City of Petalurna. Palaernon'sappearance in the Bay around the mid-1950s may be related to increasedshipping with South Korean and Japanese ports related to theKorean War.It waslikely transported inballast water or possibly, asNewman 963! argued, withinthe fouledseawater system of a ship. Palaernonis a hardyand eurytopic organism tolerating a wide range of salinitiesdown to 1-2 ppt and water of low quality. As discussed byNewman 963! andCarlton 979a!, although Palaernon's geographic distribution within the estuaryoverlaps with that of native crangonid shrimp, it is unlikely tosubstantially competewith them due to differences inhabitat use. In the Delta Palaemon mainly eatsopossum shrimp Neornysis rnercedis Herbold et al., 1992!. Palaemon hasbeen foundin thestomachs ofwhite sturgeon, white catfish and striped bass Gannsle, 1966;Thomas, 1967; McKechnie k Fenner, 1971!, and is used as sturgeon bait Herbold et al., 1992!.

Procambarusclarkii Girard, 1852!

RED CRAYFISH

SYNONYIvtS:Cambarus clarkii Girard, 1852 Thered swamp crayfish isnative to Louisiana,Texas and other southern states,where it is themain cultivated crayfish due to its rapid growth, reaching a marketable size of 7.5 cm in three months Herbold et al., 1992!,Holmes 924! reportedthat it wascollected from a streamnear Pasadena in the summer of 1924 Skinner962! andBDOC 994! statingthat it wasintroduced from the Midwest in 1925!Riegel 959! reported that the crayfish was imported in 1932by a frogfarmer in Lakeside,San Diego County for use as food, but that it mayhave already been presentin California before then. Its initial appearance inCalifornia probably resultedfrom an intentionalimportation for commercialuse or as a foodresource, followed by an intentionalor accidentalrelease Thered swamp crayfish is now widely distributed throughout the central part of thestate and is theonly crayfish found south of theTehachapis Riegel, 1959!. It hasbeen taken regularly inthe Delta Hazel & Kelley,1966!, and in 1995we found it at ShellMarsh east of Martinez.BI3OC 994! reportsthat it is fishedcorrunercially andrecreationally inthe Estuary for food and for scientific use, although Kirnsey et al. 982!. reportedonly incidental take of thisspecies for bait and sport. Thered swamp crayfish prefers warmer water than does the signal crayfish, survivesin stagnantwater by usingatmospheric oxygen, and tolerates salinities up to 30ppt. It is frequentlyfound in ricefields and sloughswith abundant emergent vegetation,It is regardedas a pestin rice fields and irrigation clitches because it eats Introduced Species Pagel00 young rice shootsand digs burrowstwo inchesin diameterand as muchas 40 inches deepinto leveesand banks Riegel,1959; Kimsey et al., 1982;Herbold et al., 1992!, and Skinner962, p. 124!described it as "mechanicallydestructive to dikes and levees."At CoyoteHills Marsh in Alameda,a freshwater/brackishwetlands on the eastern shore of south San FranciscoBay, red swamp crayfish have been shown to reducethe abundanceof sagopondweed, Potamogetort pectitratus and are preyed upon by raccoon,Procyon lotor. The reductionor elimination of submersed macrophytesby grazing crayfishmay reducemarsh diversity and secondary productionby eliminating habitat for epiphytic organisms,and on the other hand may benefitvector control effortsby reducinglarval mosquitohabitat Feminella& Resh, 1989!

Rhithropanopettsharrisii Gould, 1841!

HARRIS MUD CRAB

Rhithrapartopeusis native to the northwest Atlantic from New Brunswick to Florida and from Mississippi to Vera Cruz, Mexico, in upper estuarine areas in fresh and brackish water. It was introduced to Europe, presumably among ship fouling, by 1874, and was collected in the Panama Canal in 1969. The first records of Rhithropanope> froms the Pacific are specimenscollected from Lake Merritt, Oakland in 1937.It was subsequentlycollected from Oregon in Coos Bay in 1950,in Netarts Bay in 1976,and in Yaquina Bay and the Umpqua River in 1978 Carlton, 1979a,p. 697!. In the Atlantic Rhithropanopeusis commonly found in oyster beds Ryan, 1956,Wells, 1961;Maurer & Watling, 1973!,and it may have been introduced to San Francisco Bay with shipments of the Atlantic oyster Crassostreavirginica, which was still being imported from the Atlantic in small quantities in the 1930s.It could also have been introduced via ship fouling or ballast water. Though Rhithropatmpettshas apparently been absent from Lake Merritt since at least the 1960s,we have found it common in similar habitat among massesof the tubes of the Australian serpulid worm Picopomatusenigmatica in the Petaluma River at Petaluma, and on the shore under rocks at low tide in Carquinez Strait associated with the native shorecrabHemigrapsus oregorrensr's!. It is reported as present to abundant from San Pablo Bay to the Delta, is regularly collected at the Central Valley Project pumps at Tracy in the south Delta S. Siegfried, pers. comm., 1994!, and has been found in the Delta-Mendota Canal Carlton, 1979a!. It has recently been collected in the upper parts of sloughs in the far South Bay, syrnpatric with juveniles of the recently introduced catadromous mitten crab Eriocheir sinensis K. Halat, pers. comm., 1995!.Rhithropartopeus' planktonic larvae are caught in Suisun Bay and to a much lesser extent in San Pablo Bay, and the abundanceof theselarvae is inverselycorrelated with high outflows during the summer Herbold et al., 1992!. Jones940! suggestedthat Hemigrapsuswould be likely to outcompete Rhithropanopeuswhere their distributions overlap in SanFrancisco Bay, and Page1OI Introduced Species Jordan989! found that the distribution ofRhithropanopeus isrestricted by HemigrapsusinCoos Bay, Oregon. Inthe Delta, Rhithropanopeus iseaten bywhite sturgeon,whitecatfish andstriped bass Stevens, 1966;Turner, 1966a; Thomas, 1967; McKechnie& Fenner, 1971!.

ARTHRopoDA:INSKcTA Artisolabis rrtaritirna Gene, 1832!

MARITIME Thispredaceous maritime earwig isnative tothe North Atlantic region and hasbeen reported from Japan, Formosa andNew Zealand. It was first collected in theSan Francisco Estuary in1935, where it has been found from San Pablo Bay to CarquinezStraitbut not along the ocean coast inthis area Langston, 1974!.It was alsoreported from Nanaimo in.British Columbia in1920!, and from Laguna Beach 921!and Costa Mesa 944! in southern California, butthere are no subsequent recordsfrom these areas Carlton, 1979a, p. 702!.Reports ofthis otherwise knownonly from the seashore, typically near the high-tide level from shipments of dahliasand crysanthernums arriving insouthern California probably refer to anotherspecies. It may have been transported tothe Pacific coast insolid ballast in thelate 19th or early20th century, and remained unrecognized forsome years.

Neochetinabrttchr' Hustache and Neochetirtaeichhorrtiae Warner In aneffort to controlwater hyacinth, Eichhorrtia crassi pcs, the U S. Departmentof Agriculture introduced into Florida two weevils from Argentina, Neochetinaeichhorniae in 1972!and N, bruchi in 1974!.Both weevils were subsequentlyestablished inLouisiana andTexas, and have been introduced tomany otherparts of the world N, eichhorniae toZambia 971!, Zimbabwe 971!, South Africa974!, Australia 975!, Fiji 977!, Sudan 978!, Indonesia 979!, 979!,Egypt 980!, Myanmar 980!, Solomon Islands 982!, India 983!, 983!,Vietnam 985!, Papua New Guinea 985!, 988! and Honduras 990!;and N. bruchito Panama 977!, Sudan 979!, India 984!, South Africa 989!, Australia990! andHondura.s 990!! Qulien,1992!. TheCalifornia Department ofBoating and Naterways and the USDA, respondingtoa build-upofwater hyacinth, released N. bruchi into the Sacramento- SanJoaquin Delta beginning inJuly 1982, and N. eichhorrtiaein1982 or 1983. Althoughboth weevils have become established inthe Delta, there is no evidence thatthey have reduced water hyacinth there Thomas & Anderson, 1983; L. Thomas, pers, comm., 1994!. Introduced Species Page202

Trigonotylusuhleri Reuter

The mirid bug Trigonofylusuhleri is native to the Atlantic coastof +orth America,where it is anherbivore specialist on cordgrass Spartina spp,! commonly found on the smoothcordgrass S. alterniflora.It was first collectedon the pacific Coastby CurtisDaehler and Donald Strong in SanFrancisco Bay m 1993 DaeMer & Strong,1995!. In San FranciscoBay, where 5. alterniflarawas introducedfrom the Atlantic in theearly 1970s, Trigonotylus achieves higher densities on S. alterniflorathan is typicallyobserved on the Atlantic Coast, exceeding 10 individuals per culm about 3,000/m2!.These high densities, however, appear to have little impact on the plant's vegetativegrowth, lateral spread, inflorescence or seed production. Trigonotylus is alsofound on the native Pacific cordgrass S.foliosa Daehler & Strong,1995!. Trigonotylusseems likeliest to have beentransported to the Pacificcoast with cordgrassplants imported for erosioncontrol ar marshrestoration, possibly with the Spartinaalterniflora introduced to San Francisco Bay, if thatstock was imported as plants rather than seed.

ENTO PROCTA Barenfsia benedeni Foettinger, 1SS7!

SYNONYMS:Barentsia gracilis of Mariscal, 1965 SeeCarlton, 1979afor other synonyms,

The distributionof this Europeanentoproct in the northeasternPacific is poorlyknown, as it haslong been confused with the nativeBarentsia gracilis. B. benedenihas been recorded from San Francisco Bay since 1929 as Ascopodaria gracilis, "Barenfsia =Pedicellina!", and Barentsia gracilis!, at LakeMerritt, Palo Alto YachtHarbor and Berkeley Yacht Harbor Mariscal, 1965; Carlton, 1979a, p. 704!.It wasalso collected in Australiain the 1940s Wasson & Shepherd,1995!, from the SaltonSea in southernCalifornia in 1977 Jebram & Everitt,1982!, from Coos Bay, Oregon since 1988 Hewitt, 1993!,and in the westernAtlantic from Massachusettsin 1977-78Uebram & Everitt,1982!. Barentsiabenedeni was probably introduced to San Francisco Bay in ship fouling,or possiblyas fouling on oysters shipped from Japan, where it hasbeen reportedin MatsushimaBay Toriumi,1944!. Barentsia does not have planktonic larvaeand have not beenreported from ballast water e. g. Carlton& Geller,1993!, althoughtransport of adults on floating debris in ballast tanks might be possible.

Urnatella gracilis Leidy, 1851

Urnatellagracilis, the world's only freshwater entoproct, is nativeto North America from the northeastern and midwesternUnited Stateswest to Texas and introduced Species Page103

Oklahoma.It was first found in Europein 1939in Belgium,and later reportedfrom a few siteseastward to westernRussia, perhaps derived from a secondintroduction via the BlackSea Lukacsovics8z Fbcsi, 1967!. It hasalso been reported from India redescribed as Urnatellaindica!, Uruguay, central Africa, and Japan Eng, 1977; Emschermann,1987! and in a Floridacanal in 1977 Hull et al., 1980!. Urrtatellawas first found west of the RockyMountains in 1972-74in the Delta-Mendotairrigation canal in the SanJoaquin Valley Eng,1977!. The canalruns southfrom the Delta, and Urpatella colonies were observedlocally encrustingthe concreteside-lining at 64 km and southwardfrom the Delta. In earth-linedreaches Urnatellawas found encrustingthe shells of the Asian clam Corbiculaflaminea, pebblesand debris,and rarely attachedto the BlackSea hydroid Cordylophoracaspia. Unattachedsingle entoproct stalks, an asexualdispersal stage, were occasionally found in bottom sedimentsthroughout the concrete-linedreaches. Markmann 986! indicatedthat Urnatellawas collectedin the Deltabetween 1982 and 1984. Ernschermann987! reported that Urnafellaproduces heavily cuticularized segmentsthat under disadvantageous conditions, such as in a lowoxygen or low temperatureenvironment, act as restingbuds or hibernacula.The entoproctrarely reproducessexually, but relieson asexualproduction of specialpropagation brancheswhich, breakingoff, serveas a free-living,creeping and floating migratory life stage.Since Urnatella frequently colonizes the shellsof freshwatersnails and bivalves Lukacsovics& Pecsi,1967; Eng, 1977, Hull et al., 1980!and the surfaceof someplants, suchas cattails and reeds Lukacsovics& Pecsi,1967; Hull et al., 1980!,it was likely transportedto Californiawith aquariummaterials or ornamentalplants.

BRYozoA Alcyonidiurn polyoum Hassall, 1841!

SYYOKYMS:Alcyont'dium mytili O'Donoghue, 1.923

In California Alcyonidium polyoum has been reported from Tamales Bay Osbum, 1953!,from San FranciscoBay on shells of the introducedAtlantic mudsnail llyanassaobsoleta in 1951-52,Filice, 1959!,and in BerkeleyYacht Harbor Banta, 1963!.We alsoobserved it at Crown Beachin Alameda in 1995!and on shells of the introducedAtlantic oysterdrill Urosalpinxcinerea in FosterCity Lagoon in 1992!. In the Atlantic A. polyoumhas been reportedfrom northernLabrador and to ChesapeakeBay, and from Brazil Osburn,1944!. It hasbeen collected on Ilyanassashells in DelawareBay oysterbeds Maurer & Watiing, 1973! and in North Carolina oysterbeds Wells, 1961!.Specimens also referredto A. polyoum have been recorded from cold boreal waters. In the Pacific Ocean these records are mainly from PugetSound northward, including such locations as the offshore watersnear PointBarrow, Alaska, It seemslikely that two speciesare involved,and we considerthe shallow, estuarine records in SanFrancisco and Tomales bays to represent an Atlantic bryozoan.Alcyonidium specieshave planktotrophiclarvae, Page104 Introduced Species whichhave been found inballast water after a 14-daytransoceanic voyage0TC unpublished!.Alcyonidium species,including A.polyotem asA, mytih'!, havealso beenre orted from fouling onships WHOI, 1952!. Thus this bryozoan couldbe eitherap ballastwater introduction, ora late introduction withoyster shipments or ship fouling,

Angufnellapalmata van Beneden, 1845

AMBIGUOUS BRYOZOAN In 1993-95we found an arborescent, silt-covered ctenostome bryozoan inSan FranciscoBaywhich was tentatively identified asAnguinella palmata byWilliam Banta.We collected it frotn underneath floating docks at several locations Paint SanPab}o Yacht Harbor and Loch Lomond Yacht Harbor in San Pablo Bay; San LeandroMarina, Mission Rock, Coyote Point and Pete's Harbor in theSouth Bay!, andintertidally onrocks on the east side of Bay Farm Island inthe South Bay. A. palmataisan Atlantic species known from England, Netherlands, Belgium, France, fromMassachusetts to Florida, Puerto Rico and Brazil, and has been found in salinitiesranging from 13 to 32 ppt Osburn,1944; Prenant &Bobin, 1956!. In 1953 Osburnreported the first collections ofA. palmata from the Pacific, made by the VelcroIll in 1933-42,from Zorritos Light, Peru; Panama City, Panama; Isabel Island, Mexico;and Newport Harbor and Seal Beach, California. It has also been reported from New Zealand Gordon,1967!. Ar>gtiinellapalmata has been reported from ship hulls WHOI,1952!, and was probablytransported from the Atlantic in shipfouling. As it haslecithotrophic larvae,which spend but a brieftime in theplankton, it is unlikely to have been introduced by ballast water.

Bowcrbanki a g rac;iis Leidy, 1855

CREEPING BRYOZOAN

SYr;-ovYMS: ?! Bowerbankiagracilis of authors in referenceto certainPacific coast estuarinepopulations!; not ?!of Leidy,1855 authorof gracilis,not O'Donoghue,1926 as given in Souleet al., 1975! ?! Bowerbankiaimbricata of authors in referenceto certainPacific coast estuarinepopulations!; not ?! of Adams,18GO

We tentativelytreat here the cosmopolitanfouling bryozoanBowerbankia graci/isas introduced,Occurring in the westernAtlantic from Greenland to South America Osburn& Soule, 1953!in salinitiesdown to 10 ppt Osburn,1944!, to which region it may be native,it hasbeen reported from many other parts of the world including Hawaii,India, Englandand Saudi Arabia Soule& Soule,1977, 1985!. A number of subspeciesand varietieshave been described and these may either Page105 introduced Species representa single variable species orsome number ofdistinct species. Forexample, underthe varietal names typica, caudata andaggregata, O'Donoghue 8zO'Donoghue 923,1926! reported B.gracilis from a numberofBritish Columbia stations from. the intertidalzone to 50 meters. Soule et aL9SO! report B. gracifis as occurring from PugetSound toBaja California. Records north of central California, however, appeartobe restricted toPuget Sound asingle collection ofunreported date Osburn & Soule,1953! and Coos Bay since 1970; JTC unpublished; Hewitt, 1993!!. Osburn k Soule953! report it from collections likelymade inthe 1940s! inTornales Bayand- LosAngeles Harbor; it remains abundant inLos Angeles andMonterey Harbors Souleetal. 1980; Haderlie, 1969!. Jebrarn k Everitt 982! report a ctenostomeas "Bowerbankiacf.gracilis" from the SaltonSea. AlthoughLight 941! while reporting onencrusting estuarine communities in centralCalifornia did not mention Bowerbankia, Smith et al. 954! found it "extremelyabundant onpilings" inthe same region which, based onknowledge of Smith'susual sampling sites, probably refers toSan Francisco Bay!,and Banta 963! recordedit specifically fromSan Francisco Bay.Light and his students may have overlookedthisorganism, butperhaps a more likely scenario isits introduction into TomalesBaywith oyster shipments afterthe collecting reported byLight in 1941 or intosome other less well examined bay with oysters or in shipfouling anytime fromthe 19th century onward!, followed byintroduction intoSan Francisco Bay again,after the collecting reported. byLight! via coastal shipping orcoastwise transportoffisheries products e.g. with bait, or oysters shucked ata bayside restaurantwith the shells discarded inthe Bay, or spoiled oysters orcrabs we found Bowerbankiaonthe shell of a livecrab in HumboldtBay! dumped in the Bay!. Bowerbankiagracilisis common onoyster beds in the western Atlantic Wells, 1961; Maurer& Watling,1973! and has been reported from ships' hulls WHOl, 1952!. IntroductionsofB, gracilis may continue with fisheries products Miller, 1969, found aBowerbankia sp.on seaweed shipped with lobsters toSan Francisco! and conceivablyassmall colonies onfloating debris inballast water. Itslecithotrophic larvaeare only briefly planktonic, andthus not likely to be successfully transported in ballast water.

Bugula"neritina Linnaeus, 1758!" Thisconspicuous red-purple arborescent bryozoan hasa broadglobal distributionintemperate, subtropical andtropical waters, including Japan, Hawaii, Australia,New Zealand, both coasts ofPanama, Florid, North Carolina, the Mediterranean,andin the heated effluent from power plants in southern England whereit was introduced before 1912 Okada, 1929; Gordon, 1967; Ryland, 1971; Mook, 1976;Carlton, 1979a; Vail & Wass,1981!. Robertson 905! and Osburn 950! reportedit asabundant andconspicuous insouthern California witha northern limitin Monterey Bay, Carlton 979a! reported itsPacific coast range as Panama to MontereyBay,and Ricketts etal. 985! reported it infouling from Monterey south. However,itsrange appears tohave recently expanded northward. Kozloff 983! reportedit inSan Francisco Bay,stating that itwas not native tothe region, andwe Page106 Introduced Species commonlyobserved it there in1993 and 1994. It has also been found on the hull of a woodenship in Humboldt Bay Carlton 8cHodder, 1995!, inCoos Bay, Oregon Hewitt,1993! and in FridayHarbor, Washington M. DiMarco-Temkin, pers. comm., 1994!. Bugularteritirta has been reported asa commonmember of fouling communitiesin harbors and bays, but has also been collected from offshore waters andopen coast beds on the Pacific coast. It seems likely that two or more species of red-purpleBugula are present, including both a nativewarm-water, open coast speciesand an introducedharbor fouling species. Theorigin of thisspecies isunknown, but it wasmost likely transported to the northeasternPacific in hull foulingBugula rterifirta has been frequently collectedfrom ships' hulls WHOI,1952; Millard, 1952; Ryland, 1970!, and is highly tolerantof mercury-basedanti-fouling compounds Weiss, 1947!. Less likely, it mighthave alternatively been introduced with the few shipments of Atlantic oystersmade to southernCalifornia in the 19th century Carlton, 1979a, p. 97!, as it hasbeen reported from oyster beds in theAtlantic Wells, 1961!. Transport in ballast wateris unlikely,since Bugula neritina, in commonwith otherBugula species, has coronatelarvae that typicallyspend less than 10 hours in theplankton before settling Souleet al,, 1980;Woollacott et al.,1989!, though transport as tiny colonies attachedto floatingmaterial in ballasttanks, or ascolonies attached to' the sides of ballast tanks, might be possible.

Buguta stolonifera Ryland, 1960 SvNo~vM: Bugulacatifornica of Pacificcoast authors in referenceto certainharbor populations seebelow!

The history of this North Atlantic bryozoan remains to be worked out in San FranciscoBay. Soule et al. 980! reported that "the Bugutacaliforrtica reported as a fouling organism from ports such as San FranciscoBay and Los Angeles Harbor has recently been recognized as B. stolortifera.Although very similar to B. californica,B. stolottiferais grayish and lacks the distinctive, whorled colony patterns." Soule & Soule, 1977 writing in 1975-1976!specifically do not list B. stolortiferafor southern California stations,!Okamura 984! reportedB. stotottifera,identified by J. Soule, collected in 1982from the BerkeleyMarina, Bugula catiforrticaRobertson, 1905, remains a distinct species,apparently of more open marine conditions Soule et al., 1980!,and we thus take Robertson's905! reportof B. califorrticafrom "LandsEnd, San FranciscoBay," which is locatedon the oceanside of San Francisco,to refer to B. calr'fornicarather than B. stofortifera. We tentativelytake Soule et aL 980; writing in 1978!as the first record of B. sto1artiferafrom SanFrancisco Bay, pending the re-examinationof museum collections,A bryozoanreported as B. califorrticawas present in NewportHarbor on dockpiles at leastby the1940s Osburn, 1950!, while Reish 972! reportedB. ca!ifornicato bewidespread through Los Angeles-Long Beach Harbors, Alarnitos Bay,Marina del Rey,Huntington Harbor, and Newport Bay, based upon collections tnrroduced Species Page107 datingback to 1962.If Bugulastolonifera has not been present an unrecognized in SanFrancisco Bay for many decades, then it mayhave first become established in southernCalifornia harbors and enteredthe Bay regionin the 1970svia coastalship traffic. Bugulastolorrifera appears to be nativeto thenorthwestern Atlantic and has beenintroduced to Europeand the Mediterranean Ryland, 1971!, Panama Souiek Soule,1977! and Saudi Arabia Soule8x Soule, 1985!. Records of BugulacaIiforrrica in estuarinefouling communities elsewhere in theworld suchas Brazil, Hawaii, andJapan Marcus, 1937; Soule 6r Soule, 1967; Mawatari, 1956! likely refer to Bugula stoloniferaaswell. Soule k Soule967!, in reportingB. califorrricafrom the Hawaiian Islands,noted it was "commonas a foulingorganism on dock pilingsand boathulls and! it couldpresumably be spreadby boatsor floatinglogs." Bugula caIifornicain theGalapagos Islands may represent a mixture of boththe native marine speciesand 8. stoIarrifera. We regardB. stoloniferaas a probableship foulingintroduction. As discussed underB, "neritirra,"Bugulas are unlikelycandidates for introductionin ballast water.

Corropeumten uissimum Canu, 1908! SYYOVYMS:probably include Corropeum comrrrensale of Filice, 1959 and of Aldrich, 1961 north Bayestuarine stations! Thisvery commonwestern North Atlantic bryozoan occurs in fouling communities,on oystershells, eelgrass, and many other estuarine substrates from DelawareBav to the Gulf of Mexico Dudley, 1973!.It was first describedas a Holocenesubfossil from Argentina Dudley, 1973! and has also been recorded from WestAfrica Cook,1968! and Sydney, Australia Vail & Wass,1981!. On thePacific coastConopeum tenuissimum has beenidentified by PatriciaCook from San FranciscoBay collectedsince 1951-52; Carlton, 1979a,b! and from Coos Bay, Oregon {collectedsince 1970;JTC, unpublished!. Light's 941! record of "Membranipora"as a summer invader of Lake Merritt, Oakland,could referto eitheror both of C. tenuissimumand the cryptogenicspecies C. reticulrirn,as couMthe U. S. Navy's 951! reportof "Electrasp." on fouling panels at MareIsland in 1944-47and at Port in 1945-47. We collecteda Corropeumthat we tentativelyidentify as terruissimum on docksin the brackishnorthern part of SanFrancisco Bay in 1993-1994,where it was particularlyconspicuous overgrowing masses ofthe introduced hydroid Garveia frarrciscarra,and in scattered,small colonies on docks throughout the northern, centraland southern parts of theBay after the wet springof 1995. Crrrropeumtenuissimum has planktotrophic larvae and thusmight have beenintroduced in ballastwater Alternatively it could have been introduced in shipfouling or with Atlantic oysters with which it occurs;Maurer & WatlirLg,1973!, perhapsas early as the 19thcentury. Introduced Species Page108

Cryptosulapallasiana Moll, 1803!

ThisAtlantic bryozoan has been reported in theeastern Atlantic from Norwayand Great Britain to Moroccoand in the Mediterraneanand Black Seas Osburn,1952; Ryland, 1971, 1974!, in thewestern Atlantic from Nova Scotia to NorthCarolina Osburn, 1952! and Florida Winston, 1982!, and has been introduced tojapan Mawatari, 1963!, New Zealand Gordon, 1967! and Australia Ryland, 1971; Vailk Wass,1981!. Osburn 952! noted that it was not recorded byearly Pacific coast bryozoanworkers except fora singlequestionable 1925record from , Alaska!. Between1943and 1972 itwas reported from various southern California bays, from offshoresouthern California waters to35 meters depth, and from Mexican waters. It wascollected from Monterey Bay in 1952,Vancouver Island, British Columbia in 1970,Bodega Harbor in1975 {Carlton, 1979a, p.720! and Coos Bay, Oregon in1988 Hewitt,1993!. The U. S. Navy 951! reported aCryptosttla sp. presumably pallasiana!from Hunters Point Shipyard inSan Francisco Bayin 1944-47, Banta 963!reported C.pallasiana fromthe Berkeley YachtHarbor in1963 believing itto bethe first central California record!, and we observed small colonies onshells and floatingdocks ata fewscattered sitesin San Francisco Bayin 1994-95. Cryptosrtlawaslikely introduced tothe eastern Pacific either ashull fouling orwith shipments ofAtlantic oysters, with which it occurs on the Atlantic coast Wells,1961!. It has lecithotrophic larvaethat spend avery short time in the plankton,and thus is a poorcandidate forinteroceanic transport byballast water.

Schizoporellaunicornis Johnston, 1847! SYNONYMS:Sebi zopodrella unicornis Thisconspicuous, orange-colored, westernPacific encrusting bryozoan was notreported onthe eastern Pacific coastby early bryozoan workers, asnoted by Osburn952!. It has been reported invarious embayrnents andshore locations in Washingtonstatesince 1927, inCalifornia since1938, inBritish Columbia since1966 {Carlton,1979a, p.723!, and inCoos Bay, Oregon since1986 QTC, unpublished!. S. unicornishasalso been reported fromBaja Calif'ornia andthe Galapagos, andfrom offshoresitesin southern California, butas discussed byCarlton 979a!, these and someother southern California records maybe properly referred tothe Atlantic speciesS,errata, or to a thirdSchizoporella species. InSan Francisco BaySchizoporella unicorniswas recorded fromthe Berkeley YachtHarbor in1963 Banta, 1963!, and we collected it from various locations inthe Bayin1970 and 1993-95. Though wenever found itabundant, Kozloff983! describedit asthe most common encrusting bryozoan inthe Bay. Itis often found encrustingonshells and has been frequently reported asfouling onship hulls WHOI,1952!, and thus may have been introduced tothe northeastern Pacificeither withshipments ofJapanese oysters Crassostrea gigas!orashull fouling. Likemany Pagel09 Introduced Species otherbryozoans, ithas lecithotrophic larvaewitha briefplanktonic phase,and is unlikelytohave been carried across thePacific inballast water.

Victorellapavida Kent, 1870 This"cosmopolitan" bryozoanhas been reported from xnany, widely- dispersedsitesand from the bottoms ofvessels. Reviewing itsglobal distribution, Carlton979a! suggested thatitwas native tothe Indian Ocean andintroduced via hullfouling toEurope firstreported inthe late 1860s!, eastern North America by 1920!,Japan by1943! andeastern SouthAmerica by1947!. A 1955 record froxnthe SaltonSeahas now been recognized byJebram & Everitt 982! as representing a distinctItspecies,was collected Victorella inLake pseudoarachnida. Merritt inSan Francisco Bayin 1967, though relatively inconspicuousmatsofVictorella couldhave been present formany years before theywere noticed. Thusthis introduction. couldhave resulted fromthe ixnportation ofJapanese oysters in the 1930s!, fromthe importation ofAtlantic oysters fromthe 1870stothe 1930s!, orfrom transport ashull fouling ithas been reported fromthe bottomsofboats; Osburn, 1944!. Transport inballast water isunlikely, asVictorella's lecithotrophiclarvae are only briefly planktonic.

Watersipora"subtorquata d'Orbigny, 1852!" Sincethe 1960s two species ofWatersipora haveappeared inCalifornia where nonewere previously known. These species aredistinguished fromeach other by theshape ofthe proximal border ofthe aperture, withthe border curving intothe apertureinW. arcuata =rrigra! andcurving outward toform a sinusinW, "sabtarquata."Theidentification ofthe latter species rernams uncertain theone or morespecies witha sinusoidaperture havebeen variously referred toW. subtorcjaata,subovaidea, cucultata, atrafusca, aterrima andedmundsi! dueto the variabilityinthe characters usedtodistinguish sinusoid species andthe unstable taxonomyofthe genus Gordon 989!, forexample, referred toit as "a taxonomic 'can of W. worms"'!.arcaata was collected in southern California embayrnents fromSan Diego toSanta Monica beginning in1964 although thefirst collection isreported inthe literatureas1967; W.Banta, pers. comm., 1994!. W."sabtorquata" wasfirst collected insouthern California in1963 although thefirst clear report ofits collection inthe literatureis1989; W.Santa pers. corxun., 1994!, inDrakes Estero in1984 0.Goddard, pers.comm., 1995!and in Coos Bay, Oregon in1990 C.Hewitt, pers. comm., 1990! where,however, wedid not find it in1995!. Wefound W. "subtorquata" inSan FranciscoBayin 1992, and in Bodega Harbor, Tornales Bay,Half Moon Bay, Moss LandingHarbor and Monterey Harbor in1993-95. InSan Francisco Bayit was commonasflat circular colonies ondocks and rocks in the South and Central bays andthe southern partof San Pablo Bay, and growing in10 cm thick "reefs" ondocks Introduced Species Page110 near the mouth of San Francisco Bay in 1993and 1994.After an unusually wet spring,we found only dead or dyingcolonies in SanFrancisco Bay in 1995. Watersiporaspecimens with a sinusoidaperture, belonging to oneor more species,have been reported from many parts of theworld. Thenative region of W. "subtorquata"is thus unknown, although its distributionand spread suggests the northwestPacific as the likeliestorigin, with populationsintroduced if theseare the samespecies! to AmericanSamoa, Hawaii, the Galapagos Islands, western Mexico, Australia,New Zealand,the Carribean,Brazil, the Mediterranean,the Red and Arabianseas and the Atlantic coastof France.Watersipora species have coronate larvaewhich remain in theplankton for lessthan a daybefore settling Mawatari, 1952;Wisely, 1958!, and thus couldnot havebeen transported long distancesas larvae in currentsor in ballastwater. Transportas foulingon ship hulls seemsmost likely, as Watersiporahas been frequentlyfound both in fouling and on ship bottoms WHOI, 1952;Ryland, 1970!, and is highly tolerantof copper-basedanti- fouling compounds Weiss, 1947;WHOI, 1952;Allen, 1953;Ryland, 1970!,

Zoobotryon verticillafum Delle Chiaje, 1828!

SYNONYMS:Zoobotryott pellucidtttrt

The origin of this subtropicalctenostorne bryozoan is unknown.Alice Robertson905! reportedit in japan, Hawaii and in abundancein MadrasHarbor, India, and noted that it occurredin abundancem SanDiego Bay in the summer of 1905,where, "in water of 10 or 12 feet deep, it grew in luxuriant massesof a green tint, the whole resembling clumps of freshly hay" Robertson,1921!. Such large colonial masses to 1 m x 2 m! canstill be found in San Diego and Mission bays, colonized by anemonesand shading out and killing eelgrass A. Sewell, pers. comm.,1995!. Osburn 940; cited in Osburn, 1953!described it as circumtropical, and added records from the Mediterranean, Bermuda, Florida, Puerto Rico, the Gulf of Mexico and Braz'.. Souleet al. 980! reportits northeasternPacific ranges as extending from San Diego to the Gulf of Californiaand CentralAmerica, and "in recent years"in harborsnorth to Los Angeles.It has also been collected in New Zealand Gordon, 1967! and Australia Vail & Wass, 1981!. Zoobotryonwas collectedin RedwoodCreek in SouthSan FranciscoBay in 1993,where it was abundantand producingactive larvae K. Wasson,pers. comm.!. It is a common hull fouling organismin warm waters WHOI, 1952;Ryland, 1970!, which was its likely mechanismof introductionto California.

CHORDATA: TUNICATA Ascidia sp.

This introduced tunicateof unknown originhas been collected off and on since1983 in harborsfrom SanDiego to LosAngeles G. Lambert,pers. comm., 1995!, Page III Jntrgduced Species andin 1993-94we found it identifiedby G.Lambert!, sometimes very abundant in foulingon floating docks, from Richmond toSan Leandro onthe east shore and fromRedwood Creek to Pier39 on the west shore of SanFrancisco Bay. We know of onlyone earlier record ofan Ascidia species inSan Francisco Bay,which was collectedatTiburon and possibly in theBerkeley Marina in 1981 B Okamura,pers. comm.,1995!. The specimens, nolonger extant, were identified atthe time as the nativespecies A ceratodes. Ascidiaspecies have been reported from ship fouling Stubbings, 1961! which mayhave been the transport mechanism forthis species. Alternatively, it may have arrivedvia ballast water, since some solitary ascidians have planktonic stages from fertilizedegg through tadpole! that last two weeks or more as discussed below underCiorta intesfinalis!. In San Francisco Bay we sometimes found the amphipod Leucathoesp.,here considered tobe introduced, living within the body cavity of this Ascidia.

Botryllusschlosseri Pallas, 1774! Botryllvsaurantius Oka, 1927 =Botrylloides violaceus! Botryllussp, largezooid! ,=Botrylloidessp.! Weconsider at leastthree species of botryllidascidians to beintroduced into SanFrancisco Bay. All threeare locally common to abundantmembers of Bay foulingcommunities, sometimes forming extensive gelatinous masses. The genus- andspecies-level systematics ofthe common, harbor-dwelling, fouling botryllids are mattersof considerablecomplexity Carlton, 1979a; Monniot k Monniot,1987; Monniot,1988! and the species-level identification of all threeof the species treated here remainsuncertain or unknown. Most Americanliterature refers the common foulingspecies to twogenera, Botryllus and Botrylloides. Monniot k Monniot987! andMonniot 988! have,however, discussed the purporteddistinctions between thesetwo genera and offer compelling reasons why Botrylloides should be synonymizedunder Botryllus, an approachwe follow here. A commonbotryllid of SanFrancisco Bay with star-shaped oroval clusters of zooidswe tentativelyrefer to asBotryllus schlosseri, a common North Atlantic specieswhich Van Name 945! regarded asnative to Europeand introduced to the westernAtlantic in shipfouling. This species has up to about20 functional zooids arrangedin stellateclusters around a central,common exhalant opening. Morphologically,it is virtually identical to theB. schlosseri of Sound QTCpers, obs.; C. Hewitt, pers.cornrn., 1992!. A secondbotryllid found in SanFrancisco Bay, also with star-shaped or oval clustersof zooids,keys out to Botryllustubrratus Ritter & Forsyth,1917 S. Cohen. pers.comm., 1994!. Van Name 945! reported this species, described from Santa Barbara,to be confinedto southernCalifornia. Abbott 4 Newberry980! reportedits occurrencefrom Bodega Bay to SanDiego and in Japan,in thePhilippines, cn the Asian mainland,and on severalPacific islands. We considerthis botryllid, at leastin central California, to be cryptogenic. Introduced Species PageII2

Yet anotherbotryllid, alsovery commonin SanFrancisco Bay, has dozensof small zooidsarranged in meandering serpentine! chains and appearsidentical to CoosBay material that Hewitt 993! referredto the Japanesenative Botrylloides violaceusOka, 1927.Boyd et al. 990! also identified MontereyBay material as Botrylloidesviolaceus. Monniot 988, p. 169!has noted that the name "violaceus" for a botryllid is preoccupiedat leasttwice beforeOka's usage, and that the proper name for this speciesis Botryllusaurarttius. This speciesis illustrated in Morris et al. 980!, figure 12.30,based upon a slidetaken by JTC "J.Carlson"! at Nahcotta, Willapa Bay, Washington. Finally, we collectedanother botryllid with chain zooidsin SanFrancisco Bay in 1993and 1994,but with each zooid typically twice the size of those in B. aurantius. This appearsto be a fourth species S. Cohen,pers. comm., 1993!.It is illustrated in Kozloff 983; plate 29, as Botrylloides!based upon material from San Francisco Bay. The failure of Van Name 945! to record any botryllid sea squirt north of southern California, and its absence from all faunal accounts of the marine invertebrate biota of the Pacific coast from Monterey Bay north until the rnid-1940s, suggeststhat these now extraordinarily abundant sea squirts have been introduced. Botryllusschlosseri was first recordedin SanFrancisco Bay from fouling panels at the Mare Island and Hunters Point naval basesin 1944-1947 US Navy, 1951!, although it evidently remained sufficiently rare or localized in the Bay to escapethe attention of Smith et al. 954!. Botryllus aurantius was present in San Francisco Bay by at least 1973 JTC, pers. obs,!. Botryllus sp, " large zooid"! was photographed at the Berkeley Marina by EugeneKozloff in the late 1970sor early 1980s Kozloff, 1983, plate 29; E. Kozloff, pers. comm., 1994!. Botryllus specieshave frequently been reported from ship fouling WHOI, '1952!.Botryllus schlosseriwas introduced to the Bay either with Atlantic oysters or on ship fouling. Botryllus aurarttius may have been introduced with Japanese oysters or on ship fouling although the latter would not have been a likely. mechanism from Japan until after World War II, further suggesting a post-1940s arrival if with ships!. Botryllus sp. may also have entered with Japaneseoysters or ship-fouling. No similar large-zooid botryllid is known from the American Atlantic coast. The distribution of all three of thesespecies remains to be worked out on the Pacific coast. similar to Botryllus schlosseriare known from at least Monterey Bay to British Columbia Boyd et al. 1990;Carlton, 1979a;Hewitt, 1993;JTC, pers. obs.!. Tunicates similar to Botryllus aurantius are known from Monterey Bay to British Columbia Boyd et aL, 1990;Carlton, 1979a;JTC, pers. obs.! and may now be present in southern California as well Carlton, 1979a!.The large-zooid Botryllus is at present known only from San FranciscoBay and Pillar Point Harbor in Half Moon Bay, San Mateo County.

Ciona intestinalis Linnaeus, 1767! SEA VASE

Cionaintestinalis is one of the most widely distributed ascidiansin the world, recorded from the tropics to the subarctic.It was first described from Europe and Introduced Species Page113 appearstobe native to one or both sides of the North Atlantic Ocean. It was reported in thenortheastern Pacific at SanDiego in 1897,fonowed decades later by collections in SanFrancisco Bay in 1932,Newport Bay in 1934,several other southern Californiabays from the 1950s to the1970s, and Monterey Harbor in 1974 Carlton, 1979a,p. 732!.There are interznittent records from Vancouver Island, British Columbiain 1908-09,the 1930s Carlton, 1979a! and in recentyears G. Lambert,pers. comm.,1995!. As discussed byCarlton 979a!, there are no records of C.intestinalis fromOregon, and the few Washington and Alaska records are doubtfuL Cionaintestinalis is a commonfouler of ships WHOI, 1952; Stubbings 961! providesa photograph ofa ship indrydock whose hull is completely covered byC. intestinatis!,which was probably the initial means of transportto thePacific coast. Later introductionscould haveoccurred via ballastwater: althoughthe ascidian larvalphase, known as a tadpole,typically lasts only a fewhours, some solitary ascidiansincluding Ciona intestinalis have total planktonic phases from release of gametesthrough settlement of tadpole! that can last two weeks or more.Carlton & Geller993! foundascidian tadpole larvae in theballast water of fiveJapanese wood chipcarriers that had completed transpacific voyages of 13 to 16days, some of which werereared to Cionasp. OTC, unpublished!. Carlton & Geller993! alsofound metamorphosedascidians settled on floatingwood chips in theirballast water samples. In SanFrancisco Bay we havefound the amphipodLeucothoe sp., here consideredto be introduced,living within the body cavity of Ciona.

Ciona savignyi Herdman, 18S2 In our surveyof SanFrancisco Bay fouling in 1993-94we found both Ciona savignyi identified by G. Lambert!and C. infestinatis,the formerdistinguished fromthe latterby thepresence of flecksof whiteor yellowpigment in thebody wall and the absenceof any red pigment at the end of the vas deferens.Like Ciona intestinalis,C. savignyiwas likely transportedto SanFrancisco Bay as shipfouling or in ballastwater. It hasbeen collected from LongBeach and other southern Californiarnarinas by C. Lambertsince 19S6, when it alreadywas abundant, and is now found from SanDiego to SantaBarbara. It is probablynative to Japan G. Lambert, pers. comm., 1995!.

Molgula manhattensis DeKay, 1843!

This occurs on both sides of the North Atlantic Ocean, from Maine to Louisiana Van Name,1945! and from northern Norway to Portugal Millar, 1966!. Van Name 945! reportedit as the commonestsolitary tunicateon the coast betweenMassachusetts and Chesapeake Bay. It was first recordedin the Pacificfrom TomalesBay in 1949,was "widespread in SanFrancisco Bay in the 1950s,"and collectedin CoosBay, Oregon in 1974,and in BodegaBay Abbott & Newberry,1980!. As notedby Carlton979a!, thereis alsoa questionablerecord from SanFelipe in introducedSpecies Page114

the Gulf of Mexico.It hasalso been introduced to Europefrom the White Sea to the AdriaticSea, northwestern Africa, Japan and Australia Abbott & Newberry,1980!, In SanFrancisco Bay, Molgula has been collected from the South Bay, along theeastern shore of theCentral Bay, in SanPablo Bay and upstream to Martinezan GrizzlyBay, at concentrations ofup to 100-2,400/square meter Hopkins, 1968; Markmann,1986!. Ganssle 966! reported it asM. verrucifera!m 1963-64 as "so abundantin SanPablo Bay bottom tows that it wasimpossible to haul the trawl aboardby hand." It isapparently the most low-salinity-tolerant tunicate m theBay: it rangesfurther upstream than the others and was virtually the only tunjcate we collectedin the Bay in thesummer of 1995following an unusually wet spring. It is alsoreputed to behighly tolerant of municipaland industrial pollution Van Name, 1945;Carlton, 1979a; Abbott & Newberry,1980!. Molgulacould have been transported to central California in shipfouling fromwhich it hasbeen frequently reported; WHOI, 1952!, with oyster shipments Wells961! andMaurer & Watling973! reportedMotgula manhatfensis from Atlanticoyster beds, and we have often found it attachedtoshells dredged from the bottomof San Francisco Bay; eastern oysters Crassotrea virginica! were being plantedin bothTomales and San Francisco bays in the 1940s!,or, asdiscussed above under Ciona intesfinatis, in ballast water.

Styela clava Herdman, 1881

SYNONYMS:Sfyela barnharfi

Styetaclava is native to the westernPacific from the Sea of Okhotsksouth to Shanghai,and thoughpresent in Californiasince at leastthe 1930swas not recognizedasthe Asian species until the 1970s. It was collected atNewport Bay in 1932-33,inElkhorn Slough a single small specimen! in1935, in San Francisco Bay in 1949,in MissionBay in 1959,in Monterey Harbor in 1961,in severalbays from SanDiego to MorroBay in theearly 1970s, in Coos Bay, Oregon in 1993-94 R. Emlet, A. Moran,pers. comm,!,and in 1994-95at a marinanorth of Nanaimo,British Columbia,but notat othersites on theeastern shore of VancouverIsland G. Lambert,pers. comm., 1995!. It hasalso been introduced to northwestern Europe, northeasternUnited States and Australia Abbott k Newberry,1980!. Styelaclava is a commonfouling organism in harbors and may have been transportedto thePacific coast as ship fouling. However, since it hasalso been reportedfrom foulingassociations in Japanese oyster farms Carlton, 1979a! and Japaneseoysters Crassosfrea gigas! were planted in ElkhornSlough from 1929-1934 Bonnot,1935b!, it couldhave crossed the ocean with oyster shipments and been transportedto NewportBay with coastal shipping. As noted above under Ciona irtfesfirralis, it could alsohave beenintroduced in ballastwater. Styetacfava is harvestedand eaten in southernKorea, where it is called "mideuduck."In Japanit hasbeen blamed for an asthmatic condition in oyster shuckers,apparently caused by an allergeruc reaction when -fouled oysters are hammeredopen in poorly-ventilatedwork areas. Abbott & Newberry,1980!. PageI15 I" troduccdSpecies

VERTEBRATES

FISH Acanthogabiusflavimanus Ternrninck & Schlegel, 1845! [GOMlDAE]

YELLOWFIN GOBY, MAHAZE Theyellowfin goby is native to Japan, South Korea and China where it ranges frommarine into fresh water near sea level Brittanet al.,1963; Haaker, 1979!. It is reportedlycatadromous inJapan, moving downstream onto saline mudflats to spawn Herbold & Moyle 1989!. Thefirst yellowfin goby in Californiawas collected inJan, 1963 in a midwater trawlin theSan Joaquin River off Prisoners Point, Venice Island. The fish measured 155mrn total length, and was estimated tobe entering its second year Brittanet al, 1963!.Brittan et al,963! suggestedthat the goby was transported across the Pacific in thefouled seawater system of a ship,and Haaker 979! suggested the possibility of transportaseggs laid on fouling organisms onships' hulls. Eschmeyer et al. 983! proposedtransport in ballastwater or with live seed oysters presumably aseggs! However,except for occasionalexperimental plants, Japanese oysters have not been plantedin SanFrancisco Bay since the 1930s Carlton, 1979a!. Thegoby waswidespread throughout the Bay and Delta area by 1966 Brittan et al., 1970!and is now well establishedin centraland southernCalifornia Eschmeyeret al., 1983!.Common throughout the Bayand Delta, it hasbeen collectedfrom: lagoonsaround the Baysuch as Foster City Lagoon, Berkeley Aquatic Parkand Lake Merritt, and the salt pondsat Alviso;the Delta north to the SacramentoShip Charnel almost to the Port of Sacramento,and south to the Tracy PumpingPlant and the StocktonDeepwater Channel; the Delta-MendotaCanal at Newman, and the San Luis Reservoirin Merced County;and Contra Lorna Reservoirin ContraCosta County Brittan et al., 1970;McGinnis, 1984; ANC & JTC, pers.abs.!. It wasreported from Elkhorn Slough Kukowski, 1972! and TomalesBay andEstero Americano Miller & Lea,1976!, and onespecimen was collected from BolinasLagoon Brittan et al., 1970!.McGinnis 984! reportedthat it was expanding its range in central coastalCalifornia. In southernCal.ifornia the yeilowfingaby was photographed in LosAngeles Harboron Sept.22, 1977and collectedfrom Long BeachHarbor on Mar. 29, 1978.It hasalso been collected from upper NewportBay and the SanGabriel River »»« 1979!,and south as far as SanDiego and perhaps into Mexico Courtenayet al.,1986!. The largest specimen reported in California, with a total length of 234 mm. w» takenfrom Berkeley Aquatic Park Brittanet al,,1970!. The goby has also been introducedto SydneyHarbor, Australia Miller & Lea,1976!. 1ntraduced Species Page116

Thegoby is considereda delicacyin Japan Eschmeyer et al.,1983!, but in the BayArea it is knownto be usedonly for bait,primarily for stripedbass. It supportsa commercialtrap fishery,and individualanglers catch it by hook-and-line.

Alosa sapidissima Wilson, 1811![CLUPEfDAE]

AMERICAN SHAD, ATLANTIC SHAD

SYNONYMS:Clupea sapidissima

Shad are native to the Atlantic coast from Labrador to Florida Page BzBurr, 1991! Theywere the first fish successfullyintroduced into California.In June1871, about 10,000Hudson River shadfry, which hadbeen carried across the country in four 8-gallonmilk cansby SethGreen of the CaliforniaFish Commission, were planted in the SacramentoRiver at Tehama Lampman,1946!. A secondshipment was lost in June 1873when a railroad bridge over Nebraska'sElkhorn River collapsedand the aquariumcar wasdestroyed. A third shipmentof 35,000fry was successfully planted on July 1873.The U. S. Fish Commission made several other shipments from 1876to 1881,with all the fry, totaling 829,000,planted in the Sacramento River at Tehama Skinner, 1962; Stevens, 1972; Nidever, 1916, and Shebley,1917, report the total as 619,000!,A few mature shad were taken from San FranciscoBay by 1873,and shad were found in the Columbia River by 1876. Nidever, 1916;Shebley, 1917!.The population spread rapidly to other estuaries from Baja California to Alaska and as far away as Kamchatka,through a combination of ocean migration and intentional transplants Herbold et al., 1992!. Severalresearchers have suggestedthat shad and striped bass did well in the Delta watershed in the late 1800sbecause their drifting eggswere not smothered by sediment from gold mining operations,as presumably were the sinking or attached eggs of native fish; and becausethey spawned in the main river channelswhile the native salmonid= spawned in smaller tributary streams that were more extensively disruptedby mining activities Herboldet al., 1992;Blount, 1994!. In any eventby 1874shad were numerousenough to supporta smallcommercial harvest, and by 1880 the "catch had to be curtailed to keep from glutting the market" Skinner, 1962!, Between1900 and 1945the catchwas frequentlyover a million pounds,peaking at 5.7 million pounds in 1917 Skinner, 1962,Herbold R Moyle, 1989!.By 1953, however,Roedel described the shadas a minor commercialspecies taken with gill and trammel nets with Pittsburgaccounting for most of the landings,which totaled about 0.4-1.3million pounds annually during the 1950s Skinner, 1962!.It is unclear, however,whether the reducedcatch was due to a decliningstock or a weakmarket. Most of the sport fishing at that time was done with dipnets, and was referred to as the "bump net" fishery. The commercialfishery was eliminatedin 1957when the California legislaturebanned gill-net fishing within the GoldenGate to avoid competition with sportfishing. In the early decadesof the fisheryvirtually all of the shad weresold in local freshmarkets. Then for a whileafter 1912 most of the fishwere salted and exported Pagelid Introduced Species toChina Nidever, 1916!. By the 1950s most of themeat was again sold fresh, though themain value of thefishery was in theroe, which was salted, canned or soldfresh Roedel,Today, 1953!.spawning runs are found on the Sacramento, Feather, Yuba, American,Mokelumne, Stanislaus andSan Joaquin rivers in theDelta watershed, andin theRussian, Eel and Klamath rivers in northernCalifornia. There are also shadin MillertonLake in FresnoCounty, San Luis in MercedCounty, andin otherwaters of theCentral Valley irrigation. system McGinnis, 1984!. Stevens972! reported "crude" estimates ofover 750,000 shad running on the SacramentoRiver based on trap data, and between 2 and 4 millionfish based on past commercialcatch records. Herbold et al. 992! reported estimates of 3.04 million fish in 1976and 2.79 million in 1977on theSacramento River, with populations probably2-3times aslarge early in the century. Emmett etal. 991! estimated the combinedrun in all Deltatributaries at 0.74.0million shad per year, Studieshave shown adult shad to be wide-ranging travelers, with some individualscaught 3,000 km from the tagging site Emmett etaL, 1991!, but little is knownof theirlife in thePacific Ocean. The males usually mature in threeyears andthe females in four. The mature fish migrate upstream between February and June,with the peak migration occurring inMarch or April. Before the construction of theRed Bluff in 1967,some shad traveled more than 300 miles up the SacramentoRiver Nidever, 1916; Smith k Kato,1979!. Most spawning takes place betweenApril and June, with temperatures generally between 14'and 24'C, althoughspawn survival ispoor at the higher temperatures. Onthe Pacific coast mostadults die after spawning, which may be related to highwater temperatures Stevens,1972; Moyle, 1976a; Ernmett et al., 1991!. Moyle976a! reports that spawning females release 30,000-300,000 eggs on theAtlantic coast, shad are reported asspawning 116,000 to 4,680,000 eggs Skinner, 1962!j.The eggs can tolerate 7 5-15 ppt salinity depending ontemperature, with optimaltemperatures of16-27'C., and hatch in 3-6days Emmett etal., 1991!. Juvenilesarefound in abundancein the Delta in latesummer and fall, with most movingdownstream intobrackish water by the winter Skinner, 1962; Moyle, 1976a!,Youngshad are reported tofeed on zooplankton, primarily cladocerans and copepods,withadults in the Delta feeding onNeomysis mercedis, along with cladocerans,copepods and amphipods, andan occasional clam or larval fish. The adultscease feeding once they enter the main rivers Stevens, 1972; Moyle, 1976a!. Thestomachs of coastalshad were found to containanchovies and euphausids Skinner,1962!. Juvenile shad are prey for salmonids, striped bass, other fish, birds and harbor seals Emmett et al., 1991!. Curtis942! stated that "no detrimental effects are reported for this fish...It seemstobe possible topoint to thisspecies asthe one case which has caused no complaintfrom any quarter. It has apparently found an ecological niche which was notonly completely unoccupied but also large enough to accommodatean enormouspopulation." Ernrnett etal. 991! concluded thatthe introduction ofshad "doesnot appear to havedisplaced natives, but competition may occur." Introduced Species Page118

Ameiuruscatus Linnaeus,1758! [ICTALURIDAEj

MrHITE CATRSH, SCHWA!%KILLCAT, FORKED-TAIL CATFISH, CQMMQN CATFISH

SYNONYMS; Icfalurus catus

Whitecatfish are native to coastal streams from New York to Mississippi Pagek Burr, 1991!.In 1874Livingston Stone of the U. S.Fish Commission planted 54 or 56!large white catf'ish from the Raritan River, New Jersey along with l8 unidentifiedcatfish from the ElkhornRiver in Nebraska!in the Sa.nJoaquin River near Stockton Smith, 1896;Shebley, 1917!. In 1875,the California Fish Commission reportedthat these fish had grown rapidly and spawned, and predicted that they wouldbe numerous enough to supporta commercialfishery by the followingyear. By 1877the Commissioners reported that the descendants "already furnish an importantaddition to thefish food supply of thecity of Sacramento"and had 8,400 of them distributed to water bodies in 13 counties.In 1879,the Commissioners reportedthat white catfishhad increasedto the millionsand furnished "an immensesupply of food,"and they had 39,000of them distributedto 22 counties Smith,1896!. By 1900the fisherywas large enough to shipcatfish to Mississippi Cohen,1993!. The commercialfishery wasabolished in 1953when the catfish populationappeared to be overfished Miller, 1966a; Borgeson & McCammon,1967!, Thewhite catfish occurs in SanDiego County and possibly other parts of southern California, and in Clear Lake, and is common in warm water lakes and slowmoving areas of largerivers in theCentral Valley Curtis,1949; McGinnis, 1984!.It issaid to bethe most popular warmwater sportfish in California Herbold & Moyle1989!, with the anglingeffort in theDelta in 1962-1963estimated at almost 450,000angler days Miller, 1966a!.It is themost abundant species of catfishin the Delta,accounting for 97% of 26,000 catfish collected in the Delta in 1963-1964.Young white catfishwere taken mainly in channelsin thesouthern and easternDelta; adultswere most abundant in dead-endsloughs, flooded islands, and the San JoaquinRiver below Stockton Turner, 1966a!. The white catfish also occurs downstreamtoSuisun Bay in salinitiesof8 ppt Ganssle,1966; Herbold & Moyle 1989!. Whitecatfish collected from Clear Lake in 1943had eaten hitch, sculpin, bluegill,tule perch, black crappie, , insects, clams, and the remains of carp and coot Miller, 1966a!.The stomachsof white catfishcollected in 1953-1'954from the Deltacontained Corophium, American shad, plant and animal debris, unidentified fish,insects, clams, the crayfish Pacifastacus, andNeomysis Borgeson @ McCammon, 1967!.The stomachsof catfish collected in 1963-1964from the Delta containedseveral introduced fish and invertebrates threadfin shad, American shad, stripedbass, bluegill, Corbiculafluminea, Rithr0partopeus harrisii! and other interestingfood items terrestrialslugs, earthworms, small birds and mammals,a lizard,a pair of cootfeet! Turner,1966a!. Curtis 942! described the white catfish andthe brown bullhead as"scavengers andto some extent predators upon the eggs Introduced Species Page1 19 andyoung ofmany other fish." He and Smith 896! noted that some believed them responsiblefor the decline inSacramento perch which others have blamed on introducedstriped bass, black bass or sunfish!, and that they inhibit trout populationsinhigh mountain waters. BDOC 994! noted that white catfish can destroythe spawning sites of native fish by preying on eggs, larvae and juveniles.

AmeiurusrneIas Rafinesque, 1820! [ICTALURIDAE]

BLACK BULLHEAD Synonyms.'Ictalurtts rnelas Blackbullhead originally ranged from southern Saskatchewan andMontana tothe upper tributaries ofthe St. Lawrence River and Hudson Bay, and south to Texas,northern Mexico and Alabama Page k Burr,1991!. They were probably introducedto California along with several other species ofcatfish in 1874 Miller, 1966c;Moyle, 1976b!. They are present inmost major rivers and in some low and rniddle elevationreservoirs in California,often in shallowand silty water, includingthe Colorado, Kern and Kings rivers Curtis, 1949; Miller, 1966c; McGinnis,1984!, and are reported as common in theDelta Herboldk Moyle,1989!. In 1963-1964only 100 out of 26,000catfish .4%! collectedin theDelta were black bullhead,with mostof themtaken from the quiet waters of dead-endsloughs in the easternand southwesternDelta Turner, 1966a!;one was collecteddownstream in HonkerBay Ganssle,1966!. Black bullhead are exceptionally tolerant of highwater temperatures,,low oxygenand high carbon dioxide levels. They eat insects, crustaceans,worms, mollusks, fish eggs, fish and plants Miller,1966c; McGinnis, 1984!.

Ameir

YEL1 OW BULLHEAD

Synonyms: Ictatt

Ameirus nebulosus Lesueur, 1819! [ICTALURIDAEJ

BROWN BULLHEAD, COMMON BULLHEAD, HORNED POUT, HORNPQUT, SQUARE-TAIL CATFISH, BULLHEAD CATFISH

Synonyms: Ietalurus nebulosus

Brown bullhead originally ranged from southern Saskatchewan,the Great lakes,Hudson Bay and Nova Scotia south to Louisianaand Florida Page& Burr, 1991!,and have been introduced widely in westernNorth America Emig,1966e!, In 1874Livingston Stone of the U, S. FishCommission planted 70 brown bullhead from Lake Charnplain,Vermont in ponds and sloughsnear Sacramento Smith, 1896;Shebley, 1917!. In 187Sthe CaliforniaFish Commissioners reported that these fish hadbecome so abundantthat the population could not be exhaustedby fishing, andthey had nearly a thousandof themcaught and transplanted to otherwaters Smith,1896!, Within a fewyears they had spreadthroughout the Delta Emig, 1966e!. In 1963-1964,only 89 out of 26,000catfish .3'lo! collected from the Delta were brownbullhead, with mostof themtaken from the quiet waters of dead-endsloughs in the southwesternand easternDelta Turner, 1966a!;one was collected downstreamin GrizzlyBay Ganssle,1966!. Today brown bullhead are found in warm water habitatsthroughout California Emig, 1966e;McGinnis, 1984!, and are reportedas common in theDelta Herbold& Moyle1989!. Pat O'Brien of CDFGreports that 2 to 3 high elevationlakes in California are takenover each year by illegallyplanted brown bullhead and golden shiner. Curtis 942! describedthis catfishand the white catfish as "scavengers and to someextent predatorsupon the eggsand young of many other fish." He noted that some believedthem responsible for thedecline in Sacramentoperch whichothers have blamedon introducedstriped bass, black bass or sunfish!,and that theyinhibit trout populations in high mountain waters.

Carassiusauratus Linnaeus,1758! []

GOLDFISH

The goldfish, native to China, was the first exotic fish to be introduced into North America, some time in the late 1600s.It has been collected in the wild from everystate except Alaska, and is clearlyestablished in 27states and 2 Canadian provinces Courtenay et al., 1986!,It was introduced to California waters some time after1900, probably as a releasedpet Moyle,1976b; McGinnis, 1984!. Goldfish may be found in any low or medium elevationhabitat in California,and somesmall lakes, suchas Lake Temescal, Alameda County, have been completely overrun by goldfish McGinnis,1984!. Goldfish are common in theDelta Herbold& Moyle1989!, where theymade up 420of 12,400cyprinids /a! collectedin 1963-1964.These were mainly Introduced Species Page121 takenin Indian Slough and at Mossdale onthe San joaquin River Turner, 1966c!, butthey have been occasionally caught downstream toHonker Bay Ganssle, 1966!. Mostof the goldfish inthe Delta migrate upriver tofresher water to breed Herbold k Moyle, 1989!. Goldfishgrow to 40 cm, and females may lay up to 15,000 eggs per year. They primarilyfeed on plankton and bottom organic debris, and thus compete forfood withfry of other species McGinnis, 1984!.

Cyprirtuscarpio I-innaeus, 1758 [CYPRINtDAE]

COMMON CARP Carp,native to Eurasia, were first introduced into North America in the HudsonRiver in 1831 Courtenay et al.,1986!. In 1872Julius Poppe imported 5 carp fromHolstein, Germany and, stocking them in hispond in SonomaCounty, "did a thrivingbusiness fora numberofyears, selling their progeny for purposes of propagation."In1877 the California Fish Commission traded trout eggs for 88 young carpfrom the Japanese government, andbegan its own carp rearing program. In 1879the U. S.Fish Commission shipped 298 carp to California,planting 60 in SuttervilleLake and the rest in a privatepond in AlamedaCounty to be "at the disposalof the State Commission" Smith, 1896!. These fish may have come from a carprearing program in Washington, D.C. which, beginning with 338 carp from Germanyin 1877 and accompanied bya nationaladcampaign, supplied carp to governmentagencies throughout the country see McGiruus, 1984, for a description of"carp fever"!. In 1882the U. S.Fish Commission began delivering carp to private applicants,and in 1883the California Fish Commission purchased 600 German carp fromJ. V. Shebley,a fish-culturalistin NevadaCounty, and planted them in the SacramentoRiver near Sacramento Shebley, 1917; McGinnis, 1984; Herbold et al., 1992!. Bythe early 20th century, carp were reported from "nearly all publicand privatewaters of thestate" Shebley, 1917!. Today they are present in most freshwaterhabitats in Califorruaother than the Klarnath River drainage McGinnls, 1984!,and are abundant in theDelta Herboldk Moyle1989! where they arefound downinto brackish water in SuisunBay, being tolerant of salinitiesup to 4.5 ppt eggs!or 6 ppt youngfish! Ganssle,1966; Burns, 1966b!, Of 12,400cyprinids collected in theDelta in 1963-1964,84 percent were carp Turner,1966c!. Most of theDelta carp migrateupriver to fresher water to breed Pierbold & Moyle,1989! A largefemale maylay over 2,000,000 eggs per year. The largest carp reported from California weighed 26.3 kg McGinnis, 1984!. Carpfeed by "grubbing" in bottom sediments in shallow water, which digs up thebottom, destroys aquatic plants, and muddies the water, rendering potentially productiveareas unsuitable for use as spawning or nursery areas by other fish species McGinnis, 1984!. Smith 896, citing Jordan and Gilbert, 1894! reported that thecarp's destruction of water celery Val/isrteria might have reduced the population of canvasbackand other ducks that feed on it, Shebley917! reportedthat carp lntrodvced Species Page 122

"probablyhave been the principal cause of destructionof the Califorrua [Sacramento]perch, by eatingthe eggs and digging up thenests" as Jordan & Gilbert 894, cited in Smith, 1896!similarly reportedfrom ClearLake!, Shebley believed thatcarp were the main food of blackand striped bass, and that this outweighed the destructionof nativeperch. Burns 966b! however,found carp to be of little forage value becausethey grow largetoo rapidly. Smith 896! reportsthat both muskellungeand sealions were introduced into Lake Merced, San Franciscoin order to eliminate carp. Shebley 917! says of the introductionof carp to Californiathat "at the time theseplants were madethe carp was one of the most popular of ;they wererecommended as valuablefood fish that would thrive in all of the warmer lakes, ponds and streams of California. Much hasbeen said for and a greatdeal more againstthe introductionof carp into California...Intime, asother speciesbecome more scarce, the carp will probably become one of the state's most valuable food fishes..."However by 1942Curtis reportedthat carp"had become the most unpopular fish everbrought into California.It standsas Public EnemyNo. 1 onthe fisherman'sbooks" for preying on the spawnof other fish, muddyingthe waterand destroyingplants. BDOC 994! reportedthat considerable effort is expendedon controllingcarp in somewaters and that their spread should be prevented. Carp havesupported small commercial fisheries in Clear Lake,Lake Co. and in San Luis Reservoir, Merced Co. McGinnis, 1984!,with statewide landings in the 1960sof about300,000 pounds per yearvalued at $15,000 Davis, 1963; Burns, 1966b!.

Dorosomapetenense Gunther, 1867! [CLUPE1DAEj

THREADFIN SHAD, MISSISSIPPI THREADFIN SHAD

SYh:ONYMS:Signatosa petenertSiSatrhafaytae

Threadfin shad are native to the Gulf coast from Florida to Guatemala, north to Indiana and Illinois Page & Burr, 1991!.The California Department of Fish and Game planted 314 threadfin shad from Tennesseeinto four ponds in San Diego in 1953 Kimsey, 1954!.In 1954and 1955,1,020 of their progeny were planted in Lake Havasu on the Colorado River, and by the end of 1955"appeared to be in every habitable part of the Colorado River from Davis Dam to the Mexican border, and in adjacent irrigation ditches, canals,settling basins and the Salton Sea" Shapovalov et al., 1959!,In 1959 threadfin shad were introduced into Central Valley reservoirs as a forage fish for largemouth bass, and spread downstream to the Delta by 1961 Burns, 1966a;Turner, 1966d;Moyle, 1976b;McGinnis, 1984;Herbold et al., 1992! Though mainly found in freshwater, threadfin shadare occasionallyfound in the sea off California and Oregon. They have been taken in Long BeachHarbor, SanFrancisco Bay, Drake's Estero and HumboldtBay, and they grew well but did not spawnin the SaltonSea Burns,1966a; Miller & Lea,1972; Kschmeyer & Herald, 1983!.They are present in most lower and middle elevation freshwater habitats in California, including nearly all warm water reservoirs, and are abundant Page123 le trodaeed Species throughouttheDelta McGinnis, 1984;Herbold & Moyle 1989;Herbold etal., ]992!, Theyhave been caught atevery Department ofFish and Game sampling station in theDelta, with few were taken in the western Delta, Turner, 1966d!. They were the mostabundant species offish caught atstations east of Chipps, Island in the DepartmentofFish and Game's FailMidwater Trawl Survey for1967-1988, andwere usuallyfound east ofSherman Islandexcept during high outflow Herbold etal., 1992!. Threadfinshad are most abundant in September andleast abundant in January,sothat heavy mortality must occur during the winter months. Young Corbicula,less then 1 rnmin length,are common in stomachs in the spring Turner,Burns 1966d!.966a! and McGinnis 984! reported threadfin shad as an important foragefishfor striped bass, but Moyle 976! found them tobe a "relativelyminor componentofstriped bass diet." According toTurner 966d!, its "importance asa foragefishin the Delta may be limited because itis abundant onlyinrestricted areas ofquiet water." McConneil & Gerdes 961!found that threadfin shadfailed to provideadequate foragefor largemouth bassandblack crappie, possibly because of rapidgrowth byshad after a short spawning period,and that they may compete with thebass and crappie forcladocerans. Burns966a! reported threadfin shad asa majorfood of salmonids inlake Shasta andwhite catfish inPine Flat Reservoir McGinnis984! suggested, based onits feeding habits and its abundance in inshorezones, that threadfin shad compete forfood with the fry of striped bass and othergame fish in the San Joaquin Riverand in reservoirs Turnerargued thatsuch competitionwaslimited, because inthe summer andfall young striped bass are in thewestern Delta eating Neomysis andCorophium whilethreadfin shad are in the restof the Delta eating copepods andcladocerans. "Before thethreadfin shad was introducedinto the Central Valley of California, Kimsey 958! expressed concern overthe possibility thatthread finshad and small striped bass would compete for foodin theDelta. I donot believe that competition between the two species is severe...Relativelyfewyoung bass of this age inhabit the areas inthe Delta where threadfinshad have become abundant" Turner, 1966d!. Von GeMern & Mitchil 975,cited in Moyle, 1976b! reported thatin many reservoirs threadfin shad reduced thepopulations ofmany game fish, including largernouth bass,through competition.

Gamb@sicaffinis Baird & Girard,1853! tPOECILIIDAE]

WESTERN MOSQUITOFISH Mosquitofisharenative tocoastal drainages fromNew Jersey toMexico, and tothe Mississippi River basin north to Indiana and Illinois Page & Burr,1991!. They wereintroduced to Californiain 1922either from the southeastern United States accordingtoMoyle, 1976b! orfrom the southern Midwest according toMcGinn 1984!to controlmosquitoes. Theyare now found in nearly every low and middle elevationfresh and brackish water habitat, and may be the most widely distributed IntroducedSpectes Page 124 and numerous freshwater fish speciesin the state McGinnis, 1984!.We QTC! collected it in Lake Merritt in 1964-65,and it is today common in sloughs around the Bayand a commonanadromous or residentfish in theDelta Herboldk Moyle, 1989!. Mosquitofish are tolerantof what arenormally consideredunfavorable water conditions,including high pesticidelevels. Females produce up to 300live young per birth McGinnis,1984!. Mosquitofish compete with fry that occupyshallow shore edgeenvironments, and reportedlyprey on Californiared-legged frogs Anon., 1993!.They also eat adult Cyprtnodottsp.!, and may have contributedto the decline of a number of endemic pupfish in southern California Moyle, 1976b; McGinnis, 1984; BDOC, 1994!.

Ictaturusfurcatus Lesueur,1840! [ICTALURIDAE]

BLUE CATFISH

Blue catfish are native to coastaldrainages from Alabama to Mexico, the MississippiRiver basin north to southernSouth Dakota and westernPennsylvania, and the Rio Grande drainage Page& Burr, 1991!.In 1969,1,758 blue catfish were flown from Stuttgart, Arkansas to San Diego County and planted in Lake Jenrungs on an "experimentalbasis" Richardsonet al., 1970!,and later planted in a few other lakesin SanDiego County Taylor,1980!. Blue catfish were known to feed on the introduced clam Corbiculaflumirteawhich was "abundant and a nuisance in many southern California waters but is virtually unutilized by present game fish," and, as the largest American catfish, they were expectedto "enhanceour fisheries by providing another trophy sized fish" Richardson et al., 1970!. In 1978a 4-pound blue catfish was caught in the SanJoaquin River near Mossdale, the possible source of the specimenbeing one of 18 fish breeders in the Central Valley licensed to raise blue catfish Taylor, 1980!,Herbold & Moyle 989! report that blue catfish first appearedin the Delta in 1979,and that young-of-the-year were found in Clifton Court Forebayin 1986,but that they remain rare in the Delta.

Ictaturus punctatus Rafinesque,1818! [ICTALURIDAE]

CHANNEL CATFISH, SPOTTED

Channelcatfish originally rangedfrom the Gulf Statesand northern Mexico northward to Hudson Bay, the Great Lakes and Manitoba Pagek Burr, 1991!. It is unclear just when the channel catfish was first introduced or becameestablished in California. Shebley 917! reports it introduced in 1874,and Smith 896! reports that in that year Livingston Stone introduced some catfish, which could have been channel catfish, from Nebraska's Elkhorn River into the San Joaquin River near Stockton. Curtis 949! states that this catfish was introduced to the Sacramento River systemin 1891,but unnoticedfor manyyears. Smith 896! saysthat 250 Page125 introduced Species yearlingseachwere planted inthe tributary tothe Sacramento! and LakeCuyamaca inSan Diego County! in1891, and that 10 fish were planted inthe BalsaC}uco Bolsa C&ca?! Rtver m 1895.Moyle 976b! I~ted xt as successfully introducedaround 1925. Herbold k Moyle 989! say that it became established only afterseveral attempts tointroduce it,and was first recorded fromthe Delta in the 1940s.Miller 966b! reports that channel catfish were planted inthe Colorado River atan unknown date and have been taken from there since 1920; and that the first authenticatedcapture inthe Central Valley was in 1942. ln 1963-64only 571 out of 26,000 catfish %! collectedfrom the Delta were channelcatfish, with most taken in swifter water in channels upstream from the centralDelta Turner, 1966a!. They are now found in warm, low elevation rivers andlakes in California, butin some places will not spawn and must be maintained byhatchery stocking McGinnis, 1984!.They are common inthe Delta, especially in thechannels ofthe Sacramento River Herbold L Moyle, 1989!. BDOC 994! noted thatchannel catfish can destroy the spawning sites of native fish by preying on eggs, larvae and juveniles. Channelcatfish live up to 39 years, and grow up to 1 meterin length and 20 kgweight. A singlefemale may lay up to 70,000 eggs. They are the only warm water foodfish that is reared commercially in the state, with farms in theCentral Valley and elsewhere McGinnis, 1984!.

Lepomiscyantellus Rafinesque, 1819 [CENTRARCHIDAEj

GREEN SUNFISH Greensunfish originally ranged on the Gulf coast from Florida to northern Mexiconorth to Ontarioto Montana,and have been introduced to muchof the UnitedStates Page & Burr,1991!. In 1891afew unidentified sunfish from Quincy, Illinoiswere accidentally introduced with other fish into Lake Cuyamaca near San Diego,and green sunfish were taken from that lake by 1895. Another 36sunfish fromIllinois, possibly including green sunfish, were planted inElsinore Lake and the BalsaChico Bolsa Chica?! River in 1895 Smith, 1895; Shebley, 1917; Curtis, 1949!, Todaythey are present inmost low and middle elevation freshwater habitats in California,except in theKlamath River drainage, and are reported as common andwidely distributed in the Delta McKechnie & Tharratt, 1966; McGinnis, 1984; Herboldk Moyle,1989!. However, in1963-64, only 15 of 11,750centrarchids collected in theDelta .1%! weregreen sunfish Turner, 1966b!, Greensunfish are tolerant of hightemperatures, lowoxygen and high alkalinity,and are territorially aggressive McGinnis, 1984!. They often hybridize with bluegill, producingsterile crosses Curtis, 1949!. Predationby greensunfish nearly eliminated the California roach, Hesperoleucussymrttetricus, from the upper San Joaquin, Fresno and Chowchilla rivers Moyle,1976b!. Along with , the green sunfish competes with anotherCalifornia endemic, the Sacramento perch Archopfites interruptus!. In IntroducedSpecies Pagel26 someareas the introducedsunfish exclude the native perchfrom feedingsites, and mayhave been contributed to the perch'sextermination from its nativewaters in the Delta McGinnis,1984!. Predation by greensunfish may have alsocontributed to declines in red-legged and yellow-legged frogs BDOC, 1994!.

Lepornisgulosus Cuvier, 1829![]

WARMOUTH

SYNONYMS:Chaerrobryt tus gutosus

Warmouthare native to coastaldrainages from Virginia to Texas,the Mississippi River basin north to Pennsylvania, the Great Lakes and Montana, and the Rio Grande upstream to New Mexico Page& Burr, 1991!, and have been widely introduced elsewhere in the West Hubbell, 1966!. In 1891 the U, S. Fish Commission planted 400 yearling warmouth from the fish station in Quincy, Illinois into I.ake Cuyamaca in San Diego County, and 100 yearlings into the Feather River near Gridley, in Butte County. In 1895another 12 warrnouth were delivered to the Sissonhatchery, but died before spawning Smith, 1895;Shebley, 1917; Curtis, 1949!.They were first recorded in the Delta after 1921 Herbold & Moyle, 1989!. Warmouth are present in the Colorado River and present though rarely abundant in many parts of the Central Valley and Delta, usually in warm waters with little gradient, soft bottom, and abundant cover Hubbell, 1966;McGinnis, 1984!.In the Delta they are largely restricted to dead-endsloughs of the eastern Delta Herbold & Moyle, 19S9!.Only 240of 11,750centrarchids collected in the Delta in 1963-64 '/

Lepomis macrochirusRafinesque, 1819 [CENTRARCHIDAEj

BLUEGILL, BLUE BREAM

Bluegill are native to drainages from Virginia to northern Mexico, the Mississippi River basin north to Quebec,the Great Lakes and Montana, and the Rio Grandeupstream to New Mexico Page& Burr, 1991!.They may have first been introducedto Californiaalong with greensunfish in 1S91 Smith, 1895; Shebley, 1917!,but the first unequivocal reports date from 1908when the U. S. Fish Commission shipped bluegill from Meredosia, Illinois to California Curtis, 1949!. These were planted in Honey Lake in LassenCounty, various lakes in Placer County, ClearLake in LakeCounty, Buena Vista Lake in Kern County,Russells Lake in VenturaCounty, and the Feather,Sacramento, San Joaquin, Kings and Kern rivers,including the San Joaquin River near Stockton Vogelsand, 1931; Moyle, 1976b!.Bluegill today are widely distributed in warm freshwater habitats and are the Page127 IntroducedSpecies mostabundant sunfish inCalifornia McGinnis, 1984; Herbold & Moyle,1989!. They arecommon inthe Delta, where they accounted for26 percent of11,750 centrarchids collectedin 1963-64 Turner, 1966b!, and have been collected downstream inSan PabloBay in thewinter Ganssle, 1966!. Bluegillhave been known to spawn as yearlings, and females produce 2,000 to 50,000eggs per spawning. Inmany areas, overpopulation hasproduced populations of stuntedfish Emig,1966c; McGinnis, 1984!. 'Iheelimination ofthe Sacramento perch from its native range in theDelta hassometimes been attributed tocompetition forfood and breeding sites by the moreaggressive bluegill Moyle, 1976b; McGinnis, 1984;BDOC, 1994!, but competitionfromgreen sunfish andpredation bystriped bass and largemouth bass havealso been cited as contributing factors. Bluegill eat bass eggs McGinnis, 1984!, andmay have contributed todeclines inred-legged andyellow-legged frogs Anon., 1993;BDOC, 1994!.

Lepomisrnicrolophus Giinther, 1859! [CENTRARCHIDAE]

REDEAR SUNFISH Redearsunfish are native to the southeastern United States, ranging from the Carolinasand Florida to Missouri and Texas, and north in theMississippi River basinto southern Indiana and Dlinois Page & Burr,1991!. They were first introducedinto California in 1948 or 1949 Emig, 1966d; Moyle, 1976b}. In 1954, 3,960 redearfingerlings from the federal hatchery inDexter, New Mexico were planted in pondsinsouthern California, andin the fall of 1956 some ofthe southern California fishwere sent to ponds inthe San Joaquin Valley and the Central Valleys Hatchery. Theprogeny from these fish were then distributed toother water bodies inthe state Shapovalovetal., 1959!. Herbold &Moyle 989! report that redear sunfish were first introducedor captured in theDelta after 1949. Todayredear are present inwarm, freshwater habitats ofsouthern andcentral California McGinnis, 1984!, including a fewstreams in theSan Joaquin River drainage Brown &Moyle, 1993!. They are uncommon inthe Delta, where they are mainlyfound in the channels ofthe Sacramento River Herbold & Moyle, 1989!. Noneof the 11,750 centrarchids collected inthe Delta in 1963-1964were redear sunfish Turner, 1966b!.' Theredear isa deep-waterbottom feeder, and is less prolific than the bluegill, producingonly about 2,000 eggs per spawning McGinnis, 1984!,

Lucaniaparva Baird, 1855! [CYPRISODONTIDAE]

SYNONYMS:Cypri nodort parvus Lucania ven @sfa Lucania affinis seeHubbs & Miller965! for a detaileddiscussion of synonymy Introduced Speeres Page12B

RAINWATER KILLIFISH

The rainwater killifish is native to Atlantic coastal regions from Massachusettsto northeastern Mexico, and the Rio Grande drainage. It mainly inhabitsprotected salt and brackish waters, penetrating into fresher waters in the southernpart of its range,and up theRio Grande into the highly mineralized lower portionof thePecos River in Texasand New Mexico. It wasfirst collectedwest of thisregion in SanFrancisco Bay at Aquatic Park, Berkeley "not later than the spring of 195S,"followed by collectionsat Richmondand in CarteMadera Creek in Marin County958!, LakeMerritt, Oakland 961! andPalo Alto YachtHarbor 962!. It has alsobeen introduced into YaquinaBay, Oregon first collectedin 1958!,Timpie Springs959! and Blue Lake 961! in northwesternUtah, and Irvine Lake in southern California 963! Hubbs & Miller, 1965!. Hubbs& Miller 965! provideevidence indicating that the killifish was probably introducedto Utah and southernCalifornia with shipmentsof gamefish bluegill, largemouth bass,black crappie or bullhead! from fishery stations on the PecosRiver. They suggestthat it was transported to San Franciscoand Yaquina bays as eggs in shipments of which continued into the 1940s!,or possibly in ballast water. However, the nearly simultaneous discovery of this fish in five separate water bodies in the West suggeststhat a single transport mechanism was at work. Hubbs & Miller rejected the possibility of accidentaltransport with New Mexico gamefish planted in the San Franciscoand Yaquina bay areasbecause they could find no records of such plantings. For example,they quote from a letter Dec. 17, 1959! from Leo Shapovalov of the California Department of Fish and Garne that he had "not been able to locate any definite information on shipments of fish into Californiafrom the U. S. Fish and Wildlife Servicehatchery at Dexter,New Mexico, in relation to the appearanceof Lucartiain the SanFrancisco Bay area."However Shapovalovet al. 959! reportedthat redearsunfish fingerlings from the Dexter hatchery were planted in southern California ponds in 1954,that the redear sunfish from theseponds were then planted in SanJoaquin Valley ponds and brought to the Central Valleys Hatchery in the SanFrancisco Bay watershed! in 1956,and that between1956 and 1959 redear sunfish from thishatchery were planted into "a number of waters"in California.Given the apparentimportance of the Dexter hatchery in the 1950sas a sourceof gamefishstock for western states,and the frequentshipments of gamefishto andbetween hatcheries, private ponds and public waters with many of thesetransactions apparently never recorded!, it seems likely that transport with gamefish was responsiblefor all five introductions of killifish. Hubbs & Miller 965! discussmorphometric and meristic evidence to supporttheir contention that the Utah and southern California killifish populations originatedfrom New Mexico while the San Francisco Bay and Yaquina Bay populationsoriginated from the Atlantic coast, but thecorrelations they provide are weakat best, and are as readily explained by ecophenotypicvariation e. g. fish inhabitinginterior waters versus fish inhabiting tidal waters!.We predict that btrradaeed Species Page 129 moleculargenetic analysis would show all five introduced populations to be more closelyrelated toNew Mexico than Atlantic coast stocks.

Merridiaberyltirra Cope, 1866! [ATHERINtDAE j ,MISSISSIPPI SILVKRSIDE Synonyms:Merr idia auderrs Theinland silverside is nativeto coastaldrainages from Massachusetts to Texas,the Mississippi River and major tributaries tosouthern illinois and eastern Oklahoma,andthe Rio Grande inTexas and southeastern NewMexico Page & Burr,1991!. Inthe fall of 1967, the California Department ofFish and Game and the LakeCounty Mosquito Abatement District planted about 9,000 young-of-the-year silversides from Oklahoma intoUpper and Lower Blue Lakes and Clear Lake in LakeCounty, California, tocontrol gnats and midges andto reduce nuisance blooms ofgreen algae, although thesilverside's abilityto control either gnats oralgae had notbeen demonstrated Moyle,!976b!. The stocking intoClear Lake was apparently alsodone without the permission ofthe California Fish and Garne Commission or the"official endorsement" ofthe California Fish and Game Cook k Moore,1970; McGinrus,1984! The silverside population exploded inClear Lake, such that silversideswerethe most abundant species taken inseine hauls by the fall of 1968 oneyear after the introduction ofless than 3,000 fish!, with up to 2,500 silversides ina single haul Cook & Moore, 1970!,Silversides becamethe dominant inshore fishin thelake and, according toMcGinnis 984!, provided "the final competitive blowfor the extinction of thenative Clear Lake splittail." Inlandsilversides fromClear Lake were introduced intothree ponds in Santa ClaraCounty m 1968andtwo lakes inAlameda County in1969 and 1970, and unauthorizedtransplants, possibly occurring when these fish were used asbait, were subsequentlymadeto other water bodies inthese counties Moyle etal., 1974!. Silversideswere collected in the San Joaquin River near Manteca in 1971, and becamethe dominant inshore species there by 1976. By 1980 itwas one of the most numerousfishin the Delta system. Itscurrent distribution includes Clear Lake, CacheCreek, Putah Creeks, throughout theDelta downstream toAntioch, andin thetributary rivers and associated reservoirs ofthe San Joaquin Valley, and it continuestospread Meinz & Mecum,1977; McGinnis, 1984!. Mandsilversides tolerate a wide range ofwater conditions, including high temperatures,lowoxygen andmoderate organic poBution. Females mayspawn up to15,000 eggs per year. Inland silversides feedon zooplankton andsmall, bottom- dwellinginvertebrates inthe inshore zone,and thus may not be very effective at gnatand midge control {McGinnis, 1984!. inlandsilversides maycompete with striped bass in the Delta. McGinnis 984!found that in the rniddle SanJoaquin RiverNeomysis mercedis isthe preferredfoodofboth inland silversides andstriped bass,Silversides mayalso be a significantpredator ofthe larvae andeggs ofthe endangered Deltasmelt BDOC, introduced Species Pagel30

1994;Moyle, pers. comm.!. Li et al.976! discuss data suggesting that silversides competewith and caused a decline inthe growth rate of black and white crappie in Clear Lake.

Micropferusdolomieu Lacepbde, 1802 [CENTRARCHIDAE]

SMALLMOUTH BASS,SMALLMOUTH BLACK BASS

Synonyms:Micropterus dolomieui

The srnallmouthbass is nativeto the HudsonBay, Great Lakesand MississippiRiver drainages from southern Quebec to NorthDakota, south to northernAlabama and Oklahoma Page8z Burr, 1991!.In 1874 LivingstonStone planted73 full-grown smallmouth bass from Lake Champlain, Vermont, in Napa Creek, and 12 small bassfrom the SaintJoseph River, Michigan in . Bassapparently reproduced in both creeks, but the Napa Creek population was fishedout by 1878while the Alameda Creek population grew large enough to stock other streams.Sometime before 1879, Seth Green imported a shipmentof black bass, eithersmallmouth or largemouth,for the Sportsmen'sClub of SanFrancisco and plantedthem in I.akeTemescal in Oakland.In 1879Livingston Stone planted another22 full-grownsmallmouth bass in CrystalSprings Reservoir in SanMateo County.These increased rapidly and their progeny were planted around the state, with much of the distributionduring this perioddone by private partiesand never recorded,ln 1887black bass were reportedin the RussianRiver apparently stocked by privateparties! and by 1894anglers were illegally harvesting bass from the river with seinehauls and dynamite.From 1889to 1895state authorities engaged in a major redistributionof black bassin the state,taking many of them from the San AndreasReservoir in San Mateo County and the RussianRiver where 9,350 were collectedin 1894and 25,600fry in 1895!and plantingthem in watersfrom San Diego County to Butte County, includingthe AmericanRiver and the SanJoaquin River in FresnoCounty. At this time blackbass were alsoreported from the Sacramento River at Colusa Smith, 1895;Shebley, 1917!. Curtis 949! reportedsmallmouth bass in PutahCreek and the Russian, Feather, American,Tulomne, Stanislaus, Merced, San Joaquin,Kings and Kern rivers, with 1,890,000black bass bothsmallrnouth and largemouth!caught by anglers in 1948.Smallmouth bassare now presentin many rivers and lower and rnid-elevation lakes in California McGinnis,1984!, thoughuncommon in the Delta where they are largelyrestricted to dead-endsloughs Herbold& Moyle 1989!. None of the 11,750 centrarchids collected in the Delta in 1963-64 were smallmouth bass Turner, 1966b!. Brown & Moyle 993! reportthat a declinein nativehardhead Mylopharodon conacephalus!in streamsof the San JoaquinRiver drainage was associatedwith an expansionof smallmouthbass. Introduced Species Page131

Micropterussalmoides Lacep6de, 1802! [CENTRARCHIDAEJ

LARGElvIOUTHBASS, LARGEMOUTH BLACK BASS

SYNONYMs; Huro salrnoides Largemouthbassare said to be "the most popular warm-water game fish in NorthAmerica" McGinnis, 1984!. They are native to the Hudson Bay, Great Lakes andMississippi River drainages from southern Quebec toMontana, south to Louisiana,and coastal drainages from North Carolina to northernMexico Page k Burr,1991!. Although a pre-1879 private stocking of"black bass" inLake Temescal in Oaklandmay have involved either largemouth orsmallmouth bass, and largemouthbasswere planted in Washington state in 1890, the first unequivocal plantingoflargemouth bassinto California occurred in 1891, when the U. S, Fish Commissionplanted 620 yearlings in the Feather River near Gridley and 2,000 yearlingsinLake Cuyamaca inSan Diego County. In1895 the California Fish Commissiontook delivery of 2,500 fry which they raised in theSisson Hatchery and distributedthe progeny throughout the state. As noted above under srnallmouth bass,there was also considerable redistribution of black bass around the state at this time Smith,1895; Shebley, 1917!. Curtis949! reported largemouth bass to becommon throughout the Sacramento-SanJoaquin river system and in southernCalifornia, with 1,890,000 blackbass both smallmouth and largemouth! caught by anglers in 1948. Largemoutharereported ascommon in the Delta, especially indead-end sloughs Herboldk Moyle,1989!, although only 34 of 11,750centrarchids collected inthe Deltain 1963-64.3%! werelargemouth bass Turner, 1966b!. ln theDelta, predation by largemouthbass and striped bass may have been a keyfactor in theglobal extinction ofthe crassicauda! andin the eliminationof the Sacramentoperch Archopfitesinterruptus! from its nativerange in theDelta Moyle,pers. comm., 1993!, though competition from introduced sunfishis alsosaid to bea causeof theperch's decline McGinnis, 1984!. Predation by largemouthbass may also have contributed tothe decline ofnative red-legged and yellow-leggedfrogs BDOC, 1994!. In eastern California, predation bylargemouth basswas probably a major cause of the near extinction ofthe Owens pupfish, Cyprinodonradiosus Moyle, 1976; Wilcove etal., 1992!. Curtis 942! reported that troutdeclines in somewaters are caused by black bass, It isinteresting to note that evenas they made the initial plantings, fishery agents were aware of the bass' potentialtoreduce native fish populations. AsSmith 896! reported, "State fish commissionershave refrained from depositing fryor yearling bass in watersalready stockedwith salmonor trout,but haverestricted the distribution to lakes, reservoirs,ponds, and rivers in which the predaceous bass could do no damage. It seemsonly a questionoftime, however, when the bass will naturally find their way intoand become abundant in all thoserivers in whichthey have not already been planted." Largemouthbass have also been introduced toEurope and Africa Emig, 1966a!. IntroducedSpecies Page132

Morone saxatitis Walbaum, 1792! [PERCICTHYIDAE]

STRIPED BASS, STRIPER, ROCK BASS

SYNONYMS: Roccus saxatilis, Roccus lineatus

The striped bassis native to the Atlantic coastfrom the St. LawrenceRiver to northern Florida, and the Gulf coast from western Florida to Louisiana Robins & Ray,1986!. In 1879Livingston Stone planted about 135 fish from a shipmentthat startedas 132fish, 1.5to 5 incheslong, plus 30 medium-sizedfish! from the NavesinkRiver, New Jerseyin CarquinezStrait at Martinez,In 1882,a little over 300fish {from a shipmentthat startedas 450fish, 5 to 9 incheslong! from the ShrewsburyRiver, New Jerseywere plantedin CarquinezStrait at Army Point, Benicia.By 1889,hundreds were being sold in the SanFrancisco markets Shebley, 1917!.Several workers have theorized that conditions in the late 1800s"probably favoredstriped bass and Americanshad reproduction,because their semi-buoyant eggswould not be smotheredby silt from gold mining operations"{Herbold et al., 1992!,unlike the eggs of many native fish that are laid in the bottom gravel or attached to submerged vegetation or other substrate. Striped bass are present today in the Sacramento-SanJoaquin river system, in San Antonio Reservoir, in Lake Mendocino and in the lower Colorado River McGinnis, 1984!.Unsuc«essful attempts were also made to establish striped bass in the Salton Sea Roedel, 1953!. Land-locked populations exist in Millerton Reservoir in Fresno County a self-sustaining population! and San Luis Reservoir restocked continuously by means of water imported from the Delta, which entrains young bass!. Striped bass were' propagated in hatcheriesby the California Department of Fish and Game and annually released to the Delta from 1982to 1992,when stocking was curtailed due to concern over predation on the endangeredwinter-run chinook {BDOC, 1994!.An estimated 80 million fry were entrained by State Water Project pumps eachyear, and 165million fry a year by the cooling water intakes for the PG&E power plants in Antioch and Pittsburg. The striped bass population dropped from an estimated4 million fish in 1960,to 2 million in 1970,to 1.million in 1980{McGinnis, 1984!. Herbold et al. {1992!reported the populationin the Estuary at 1,480,000to 1,880,000prior to 1976,and 520,000to 1,160,000after 1977. Striped bass were the most common fish collected in trawls of sloughsin 1979-86 Brown, 1987!.They werereported as abundant in the Delta {Herboid & Moyle, 1989!,and common to abundant in San FranciscoBay Emmett at al,, 1991!,Striped basswere also reported as common in Tomales Bay, and in Coos Bay,the Uinpqua River and the Siuslaw River in Oregon.They havebeen reported north to British Columbia and south into Mexico, but populations in the southern bays are not self-sustaining Emmett at al., 1991!.Striped bass from the San Francisco Bay watershedhave been captured from centralOregon to southernCalifornia, but most travel no further than 40 km from the Golden Gate Herbold et al., 1992!, Page133 bit roducedSpecies

Meanfecundity for striped bass has been reported at243,000 eggs for 4-year- olds!to 1,427,000 eggs for 8-year-olds andolder!. A 5-poundfishspawns upto 25,000 eggs,a 12-pound fishup to 1~0,000 eggs, and a 75-poundfishup to 10,000,000 eggs CDFG1987; Exnmett atal., 1991!. Herbold etal. 992! reported that "females commonlybroadcast froxn500,000 to4.5 million eggs Hassler 1988!, although estimatesrange from 11,000 Moyle 1976! toa highof5.3 xnillion Hollis 1967; Hardy 1978;Wang Striped 1986!."bass eggs are found from fresh water to salinities of11 ppt with optimalsalinities between 1.5and 3.0 ppt! and tolerate temperatures of12-24 C with anoptixnuxn of18'C!. Larvae occur in both freshwater andoligohaline water. Juvenilesandadults are found in allparts of the estuary. Most males mature in their2nd or 3rd year, females intheir 4th or 5th year. Maximum reported age is over 30 years,Stripedbass fry are pelagic carnivores feeding on small invertebrates. Juvenilesandadults are epibenthic andpelagic camivores, thejuveniles feeding on theyoung ofsmall fish and larger invertebrates, whilethe adults are prixnarily piscivorous McGinnis, 1984; Emmett atal., 1991!. Thecomxnercial catch in 1899,2 decadesafter introduction, was 560 tons and usuallyexceeded 450tons up to 1915. Comxnercial fishingin the Estuary was banned in 1935to avoidcompetition with the sport fishery. Although there is nolonger a commercialfishery, "each year thousands ofkilograms of illegal striped bass are believedto maketheir way to restaurantsand fish markets in thegreater San FranciscoBayarea. Some ofthese come from massive nighttime netting operations in thelower Delta area. Small time operators, however, simply use standard sport fishingtechniques tocatch far more than the legal limit and then proceed directly to soxnelocal buyer" McGinnis,1984!. Stripedbass isthe principal sport fish caught inSan Francisco Bay,and the economicallyxnostimportant fishin the Delta. The sport catch ranged from 107,000 to403,000 fish in 1975-78 Emxnett atal., 1991!. ln 1980 California anglers took about 1 xnillionbass, spending about $7 million in theprocess McGinnis, 1984!. 'The subsidiaryindustries surrounding striped bass fishing boats, marinas, and paraphernalia!areestimated tobring $45 million into the local economies" HerboldStriped et al.,bass 1992!. were the most numerous predator atthree saxnpled locations in theDelta Pickard etal,, 1982!. Moyle has suggested thatstriped bass and largexnouth basspreyed on and contributed tothe global extinction ofthicktail chub Gila crassicauda!,andthe elimination of Sacramento perch Archoplites interruptus! fromits native waters in theDelta Moyle, pers. comm., 1993!, though competition withintroduced sunfish has also been raised as a factorin the decline ofthe perch McGinnis,1984!. Striped bass have been reported asa majorpredator ofsalmon fingerlingsinthe Delta USBR, 1983!, though formed only a minor componentofthe stomach contents ofsubadult andadult striped bass collected in theDelta in 1963-64 Stevens, 1966!. BDOC 994! noted that few young salmon are eatenbystriped bass inthe Estuary except atsalmon stocking sites and !,butsometimes form a substantialpartof the diet of striped bass upstream Pagel34 Introduced Species in theSacramento River, and concluded that striped bass predation reduces salmon abundanceby an unquantifiedamount.

Noterrtigonuscrysoleucas Mitchill, 1814! [CYPRINIDAK]

GOLDEN SHINER Thegolden shiner is native to coastal drainages from Nova Scotia to Texas, andthe Hudson Bay, Great Lakes and Mississippi River drainages west to andOklahoma, and "widely introduced via bait buckets! elsewhere in U. S." Page 4 Burr,1991!. It wasimported into southern California in 1891, and was widespread in theSacramento-San Joaquin River system by 1964 Kimsey & Fisk,1964!, probably distributedasbait releases byanglers Herbold k Moyle 1989!. In 1963-64,212 of 12,400cyprinids 'Io! collected in theDelta were golden shiner, mainly taken in dead-endsloughs Turner, 1966c!. They are reported as widely established in California Moyle, 1976b; McGinnis, 1984! and common in theDelta Herbold8z Moyle, 1989!. Thegolden shiner is one of threelegal freshwater bait fishes in California the others,also nonnativefish, are red shinerand fatheadminnow!, supportinga "ratherlucrative small industry"of bait fishpropagation and leadingto its wide distributionin the state.It is a popularbait for stripedbass McGinnis,1984!. Goldenshiner reportedly compete with both native cyprinids and the fry of somegamefish McKechnie, 1966b; McGinnis, 1984!. Trout production in somelakes hasbeen reduced by competitionbetween trout parr and golden shiner McGinnis, 1984!.Pat O'Brien of the CaliforniaDepartment of Fishand Game reportsthat 2 to 3 high elevationlakes in Californiaare takenover eachyear by illegally planted brown bullheadand golden shiner.

Percina niacrolep;ia Stevenson, 1971[PERCIDAEj

BlGSCALE LOGPERCH

SYNONYMS:Percirta caproles

The native range of the bigscalelogperch runs from the SabineRiver in Louisianato the Red Riverin Oklahoma,the Rio Grande drainage in Texasand New Mexico,and Mexico Page& Burr,1991!. It wasaccidentally introduced from Texasin 1953in an airplaneshipment of largemouthbass and bluegill that was plantedin Miller, Blackwelderand Polk lakes at BealeAir ForceBase, Yuba County, by theU. S.Fish and Wildlife Service. The lakes are in theYuba River drainage, a tributaryof theSacramento, and regularly overflow Shapovalov et al., 1959; Moyle, 1976b;McGinnis, 1984!- By 1972-73the logperch was established in the lower SacramentoRiver and the Delta Moyleet al.,1974!, and are now widespread throughoutthe Sacramento-SanJoaquin river system Moyle, 1976b; McGinnis, Introduced Species Page135

1984!and common in theDelta Herbold8z Moyle, 1989!. They are also abundant in LakeDel Valle in AlamedaCounty, probably pumped in from the Delta via the State WaterProject pumps and the South Bay Aqueduct Moyle et al.,1974!.

Pimephalespromelas Rafinesque, 1820 [CYPRINIDAE]

FATHEAD Thenative range of thefathead minnow runs from Quebec to theNorthwest Territoriesand southto Alabama,Texas and New Mexico Page& Burr, 1991!.The first recordof it in Californiais from a baittank nearthe ColoradoRiver in 1950.In 1953,40,000 were imported by a fishbreeder in Turlock.The California Department of Fishand Game purchased 1,000 of thesefish, spawned them at the Central Valleys Hatchery,and planted the progeny in variouswater bodies as forage fish Shapovalovetal., 1959!. The fathead minnow is oneof California's three legal freshwaterbait fish, and it hasbeen further spread through the state as bait releases byanglers McGinnis, 1984; Herbold & Moyle,1989!. Herbold & Moyle989! report it firstappearing inthe Delta in the 1950s, where it is now occasionally collected and commononly in localizedpatches, generally in smallcreeks. Thefathead minnow is tolerantof high temperatures,low oxygenand organicpollution McGinnis, 1984!. It hasthe potential to competewith the ecologically-similarnative, the California roach Hesperoteucus symmetricus, whose distinctforms may actually be separate species Moyle, 1976b!. McGinnis 984! warnedthat its "abilityto establishpopulations readily in poolsof intermittent streamsand backwaterareas in Californiaposes a seriousthreat to severalnative cyprinidsadapted to suchhabitats."

Pomoxisannutaris Rafinesque, 1818 [CENTRARCHIDAE]

WHITE CRAPPIE Pomoxisrtigromaculatus Lesueur, 1829! [CENTRARCHIDAE]

SYNONYMS;Pomoxis sparoides

BLACK CRAPPIE,CALICO BASS, STRAWBERRYBASS Theblack crappie isnative to theeastern United States from Virginia to Texas andnorth through the Mississippi River basin to theGreat Lakes. The white crappie'snative range runs from the Gulf coast between Alabama and Texas north throughthe Mississippi River basin to the Great Lakes and Hudson Bay Goodson, 1966a;Page & Burr,1991!, The history ofthe introduction andspread ofthese fish in Californiais uncertainbecause there were numerous attempted introductions, both IntrodNcedSpecies Page236 successfulandunsuccessful, andbecause some authors failed to distinguish or confused!the two fish. Thefirst recorded introduction ofthese fish on the Pacific coast was near Seattle,Washington in1890. In1891, 285 yearling black and white crappie from the V.S. Fish Commission station atQuincy, Illinois were planted inLake Cuyamaca nearSan Diego. Vogelsang 931! and Goodson 966a! state that this introduction wasunsuccessful. In 1895 a secondshipment, of50,000 fry, was sent to the Sisson Hatchery,but none survived Smith, 1895; Shebley, 1917; Curtis, 1949!. Goodson 966a!states that another unsuccessful attemptwas made in1901 citing Vogelsang 931!who, however, makes noreference toa 1901 attempt!. In1908, crappie from theIllinois station were planted inHoney Lake in Lassen County, Vera Lake in NevadaCounty, Clear Lake in Lake County, insloughs and tributaries ofthe Feather,Sacramento, SanJoaquin, Kingsand Kern rivers including theSan Joaquin Rivernear Stockton inthe Delta!, and possibly atother sites in southern California Shebley,1917;Vogelsang, 1931;Goodson, 1966a!. Ofthis effort, Vogelsang 931! impliesthatboth species ofcrappie wereintroduced Vogelsang introduces hispaper asan account of"the first successful introduction ofthe crappie, calico bass [=respectively, thewhite crappie andthe black crappie; Smith 896! and Shebley 917!use the same nomenclature!, bluegill and green sunfishes andthe yellow perch"intoCalifornia, although inthe rest of the paper heonly refers to"crappie"!, Shebley917! states only that the white crappie was introduced, andGoodson 966a!argues that probably only the black crappie was introduced, since white crappiewere not reported north of theTehachapi Mountains until 1951. Goodson966a! reports the introduction of16 crappie from an unknown sourceinto a pondinSan Diego County in1917, and the subsequent stocking ofnine SanDiego County reservoirs fromthat pond. Since only white crappie have since beenreported from these reservoirs, heargues thatthe original plant of16 fish were allwhite crappie, and that all white crappie inCalifornia aredescended fromthose 16fish. Curtis 949! reported thewhite crappie surviving onlyin the San Diego area andthe Colorado River drainage, andthe black crappie widespread inthe state. Nearly3 million crappie were caught inthe state in 1948, mainly insouthern California,In1951 white crappie fromone ofthe San Diego reservoirs wereplanted ina reservoirin Colusa County, and subsequent plants were made in other Californiawaters Goodson, 1966a!. Moyle{1976b!, more-or-less consistentwith Goodson, liststhe black crappie as introducedin1908 citing Vogelsang, 1931!and the white crappie asintroduced, fromIllinois, in1917 citing Curtis, 1949, who, however, describes bothspecies as introducedin 1891!. Herbold k Moyle 989! list the "year of introduction orfirst capture"inthe Delta as1908 forthe black crappie and1951 forthe white crappie. We reliedon Moyle's dates for our analysis. Blackcrappie are today present inlow and middle elevation reservoirs and slowstreams McGinnis, 1984!.They are common inthe Delta, accounting for71'/o ofthe 11,750 centrarchids collectedin the Delta in1963-1964 Turner, 1966b!, and haveon occasion been collected downstream toMartinez Gannsle, 1966!. McGinnis 984!reported thewhite crappie's distribution asthroughout southern California andin Clear Lake. Itis apparently uncommon inthe Delta, with only one white Page137 Introduced Species crappieoutof 11,750 centrarchids collectedthere in 1963-1964 Turner,1966b!. A largecrappie canproduce morethan 200,000 eggsper spawning McGinnis, ! 984!»study oftheir feeding habits inthe Delta, black crappie mainly ate threadfinshadand striped bass,along with small numbers ofchinook salznon, Delta smeltand other fish Turner 1966b!, Curtis 949! reported thatcrappie compete with bass for food.

Tridertfigerbifasciatus Steindachner []

SHIMOFURI GOB Y It wasdiscovered in1994 that the introduced gobies inCalifornia called chameleongobiesconsisted oftwo different species. Theshimofuri goby, native to JapanandChina, isadapted tofresher water than the chameleon gobyand was first recordedin!985 from Suisun Bay, having probably arrived inballast water. By1989 it wasthe most abundant fishin Suisun Bay, and by 1990 the most abundant larval fishin the upper Estuary. By1990 ithad also been transported 5 kmsouth viathe CaliforniaAqueduct toPyramid Reservoir, andthence into Piru Creek by1992 MaternExperiments& Fleming,indicatein prep.!. thatif theshimofuri goby disperses tocoastal waters harboringtheendangered tidewater gobyErccyclogobius rtewberryi,it couldhave a substantialimpact bypreying onjuvenile tidewater gobies, competing forfood, and disturbingmating activities Swenson & Matern, 1995!.

Tridentigertrigonocephalus Gill,1859! tGOBIIDAE] CHAMELEONGOBY, TRIDENT GOBY, SHIMAHAZE Thechameleon goby is native to marine and brackish waters of Japan,China andSiberia Eschrneyer etal., !983!. One specimen 0.4 mrn standard length! was collectedfrom Los Ange!es Harbor in June 1960, with others were collected there in 1977 Haaker, 1979!. Itwas collected from the Redwood Citydocks insouthern San FranciscoBay in 1962 Matern & Fleming,ln prep.! Variousworkers have suggested that the goby could have been transported acrossthe Pacific inballast water, in ships'seawater systems, aseggs laid on fouling organismsonships h»», or fortransport toSan Francisco Bay!as eggs laid on importedJapanese oysters Hubbs & Miller, 1965; Haaker, 1979!. However, except for occasionalexperimental plants, Japanese oysters have not been planted in San FranciscoBaysince the 1930s, and have never been planted m LosAngeles Harbor Carlton,The1979a! has also become established in Sydney Harbor, Australia Haaker, 1979!. Introduced Spcci

A MFHIBIANs

Rana catesbeiarra

AMERICAN BULLFROG

The bullfrog is native to North Americaeast of Coloradoand New Mexico, and has becomeestablished in mostwestern states, Hawaii, Mexico,Cuba, Japan and Italy Stebbins,1966!. The bullfrogappears to have beenindependently introduced to Californiaseveral times between 1910 and 1920.Bullfrogs were reported,but not confirmed,from Little Lake, Inyo Countyin 1918,and from ponds on the Stanford Universitycampus in 1920.In July, 1922,adult and tadpolebullfrogs were collected from SonomaCreek near El Verano,Sonoma County. Thesefrogs were believedto be the descendantsof 132 frogspurchased from New Orleansand 12 frogs purchasedfrom a SanFrancisco frog merchantin 1914and 1915 and planted in a nearbyreservoir. Bullfrogs were alsocollected from Mockingbird Lake,Riverside County in 1922and then from other lakesand streamsin the area,possibly derived from a stockof Illinoisand Louisiana bullfrogs kept by thephysiology instructor at the LornaLinda Collegeof MedicalEvangelists since at least1914 Storer,1922; George,1927!. Moyle 979! reportsthat in 1929bullfrogs were collectedfrom the Kings River and planted in the SanJoaquin River near Friant, and were introduced tno ponsat the SanJoaquin Experimental Range in MaderaCounty in 1934. Thebullfrog was well establishedin theSan Joaquin Valley by 1930,and is now commonin many parts of California,including the Delta Moyle, 1973;Herbold & Moyle, 1989!.Although several authors have reported that reductions in populationsof the Californiared-legged frog Ranaaurora, and possiblyof the foothill yellow-leggedfrog Rara boylii, may be dueto predationby or competition from bullfrogs Moyle, 1973;Herbold & Moyle,1989; Anon., 1993; BDOC, 1994!, other factors including overharvestingof red-leggedfrog prior to the introduction of bullfrog, habitatchanges, and predation by introducedfish! make it difficult to assess the bullfrog's true impact Harvey et al., 1992!, Introdvced Species Page139

RKFITLEs pseudemysscripts

POND SLIDER, RED-EARED SLIDER

Pond sliders are native to the eastern United Statessouth to Panama Stebbins,1966!. They were presumably introduced toCalifornia as released or escapedpets and are common in the Delta and elsewhere in California Herbold & Moyle,1989; Harvey et al.,1992, p. 180!.The frequency with which they are encountered,our ANC!observations of a fernalelaying eggs and af live,hatched youngin a nestat San Pablo Reservoir in Alameda County in July 1994, and reports of reproducingpopulations atsites surrounding the Estuary in PutahCreek in SolanoCounty, Walnut Creek and Jewel Lake in ContraCosta County, Boronda Lakein SantaClara County and Stow lake in SanFrancisco County; Harvey et al., 1992!,suggest that they are almost certainly established in the Delta as weB. Althoughreportedly banned in theearly 1970s Harvey et al.!,we ANC!have recentlyseen live sliders for salein Asianmarkets in SanFrancisco. Inl raducedSpecies Page140

Mammals

Ondatra zibethicus

MUSKRAT

The muskrat,native to the easternUnited States,is commonin the Delta and other parts of California in riparian woodland,freshwater and brackishmarsh, and aquatichabitats oosselyn, 1983; Herbold & Moyle,1989, Harvey et al.,1992!. Muskrat candamage banks and levees with theirburrowing. Skinner962, p. 161!reported that over the previous twenty years muskrat had "risento thestatus of the mostimportant fur bearerin the state,in termsof numberof animalsand total value of theraw furs...Originally introduced into the northeasterncounties, they have moved down the Sacramentoand into the San Joaquinsystem since 1943." He reports trap data for the state beginning in 1921-22, andfor the starting in 1939-40,with the number trapped annuallyin the BayArea rising from less than 100 until 1950to between6,000 and 9,S00in 1951-S6,Herbold & Moyle989, citing a 1962report! reported about 11,000 trapped annually in the Delta. Introduced Species

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CHAPTER 4. CRYPTOGENIC AND UNIDENTIFIED SPECIES IN THE SAN FRANCISCO ESTUARY

Numerousspecies of marineplants and animalsoccur in the SanFrancisco Estuarywhose status as introduced or nativeorganisms remains unknown. These taxaare known as cryptogenic species Carlton, l995!. We list here examples of 123 suchtaxa Table2!. Many additionalunidentified or taxonomicallyunresolved marineprotists and smaller invertebrates exist in theBay's estuarine margins as well and are not treatedhere. These include, in particular,roundworrns !,flatworms turbellarians!, rotifers, harpacticoid copepods, and many speciesof planktonicand benthic ciliate protozoans, These unidentified taxa representingat least an additional25 distinctmorphological entities!, including membersof groupsalso commonly occurring on oyster shells and in ballastwater, areoften found abundantly amidst communities dominated by speciesrecognized as introduced,Most of the specieslisted in Table2 representone or moreof the following categories: 1! Speciesfrequently reported from foulingcommunities or planktonic assemblagesin manycool- to warm-temperateharbors and ports around the world and which represent taxaeasily transported with oysters,in ship fouling,in solidship ballast, in ballastwater, or by othermeans. 2! Specieswhose estuarine populations may represent a different species from populationsoccurring on outer,high-energy, full marinecoasts that bear the same name. 3! Speciesbelieved to have appearedrelatively recently in the Estuary. 4! Speciessymbiotic with known introducedspecies. The taxonomyand distribution of the taxa listedas cryptogenic usually remain sufficiently unresolvedas to prevent a clearresolution of their endemic versusexotic status without further data, In somecases, a speciesname is available; in other cases,only generic assigrunentsare possiblebut enough evidenceis at hand to question whetherthe taxoncan automaticallybe considerednative. In a number of cases e. g. diatoms and other phytoplankters;hydroids! we have chosenexamples of genera within which one or more and sometimesmany! specieshave been reportedfrom the Estuary that representcosmopolitan taxa potentiallytransported by human dispersal vectorsand whoseaboriginal history m the EasternPacific has not yet beenworked out. It is worth noting that cosmopolitanspecies represent one of three biogeographiccategories: ! a single specieswith truly broad and/or disjunct distributionsachieved by naturalmeans, ! a singlespecies spread by human- mediatedtransport, or ! multiplespecies described as a singlespecies. Combinationsof thesecategories may complicate this trichotomy. Thus, one or morespecies may be spreadglobally by a mixtureof naturaland human-mediated mechanisms,creating a complexintermingling of pureand hybrid populations which are thendescribed as a singlecosmopolitan species. CryptogenicSpecies PageISO

The importanceof recognizingcryptogenic species in elucidatingpotentially profoundchanges to theenvironment is discussed in Chapter 6. Asnoted there, no introduceddiatoms, dinoflagellates, or otherphytoplankters such as chlorophyceaens,chrysophyceaens, cryptophyceaens, or cyanophyceaens! have been recognizedfrom the Bay, despite a reportedAora that includes many cosmopolitan taxa. Prominentcryptogenic guilds in the Bayinclude phytoplankton 5 percent!, annelid worms9 percent!,protozoans 5 percent!,and cnidariansand crustaceans about 10 percenteach!.

Table 2. CryptogenicSpecies in the SanFrancisco Estuary

Nasnesof generalisted withoutspecies indicate at leastone cryptogenic species.Names of genera followedby "spp."indicate at leasttwo cryptogenicspecies.

I+] indicates San FranciscoBay populations, distinguished from open coast populations bearing the same name

M!CROALGAE Bacillariophyceae Diat oms} A chrrar>thes Asteriortella Aulacoseira = 1Welosira! spp. includin g A. distans var. lirata and A, granulata! Bt'ddulphia spp. Chaetoe eros s p p, Coscjnodiscusspp. Cyclotella spp. including C. caspia! Kavicula spp. Nit schia Pleurosigma Rhizosolenia Skeletonema including S. costaturn[+]! Thalassiosira including T, decipierts! Tha !as si o t h ri x Di nophyceae Di nof! agel1 a tes! Dirtophysis Gonyau!axspp, Gymnodinium Protoperidi ra u m spp. Chlorophyceae JV!o n o rap h idium Scenedesmus Cryp tophyceae Micr oflagella tes! Chroomonas minuta Cry ptomonas Cyanophyceae Blue-Green Algae! Anabaena Os ci l la t or i a Cryptogertic Species Page 151

Table2. CryptogenicSpecies - continued

MACROALGAE Seaweeds! Chlorophyta GreenAlgae! Cladophora Errferomorpha"irtfesfirtalis [+! Errteromorpha spp. Ulofhrix Ulva "lacfuca" [+] Rhodophyta Red Algae! Gigartirra sp. Graci laria verru cosa Grateloupia fforyphora

VASCULAR PLANTS Dicotyledones Myriophyllum sibtricum Polygorrum amphibium

PROTOZOANS examplesonly! Epizoicor endozoicciiiates Acirtetasp, on the introducedgribble isopodLimrtoria! Artcisfrumirtakajoidi in the introduced clam Petricolaria! CiliateA {in the introducedshipworrn Teredo navafis! Ciliate 8 in the introduced shipworrn Teredorravalis! Ciliate Sl on the introduced isopod Sphaeromaquoyartum! Ciliate S2 on the introduced isopod Sphaeromaquoyartum! Cocbliopbilusdepressus in the introducedsnail Ovafella! Cochliophilus minor in the introduced snail Ovafella! Epistylissp. on the introduced gribble isopod Limrroria! Operculariasp. on the introducedgribble isopod Limrtoria! Vorticellaspp, on the introduced gribble isopod Limnoria! Fotding ciliates Suctorian sp. A Vorficella sp. Zootham rtium sp p. Free-living BenthidFouling ciliates S pr'rorhyrrchusver rucosus Planktonic holotrich ciliates Mesorfirtium rubrum Foraminifera Ammobaculifes exiguus Milammina fusca Crypt ogenic' Species Page 252

Table 2. CryptogenicSpecies - continued

INVERTEBRATES Porifera Scyphasp, Rotifera Synchaetabicornis Cnidaria Hydrozoa examplesonly! Bougainvillia ramosa Campanularia CIyt ia Cryptolaria pulchella Conothyraea Plumularia Sarsiaspp. Sertularella Sertularia Syncory»e ex<'mia Anthozoa Nematostella vectensis Aetridium senile [+J

Pla tyh elminth es Trematoda Austrobilhar.ia varigla»dis Turbellaria Child>a groe»la»dtca Nemertea Lineus ruber Annelida Oligocha et a Aulodrilus li mnob>us Bothr>oneurumvejdot skyanurn Limnodrilus hoffmeisteri Li>nnodrilus udekemianus Polychaeta Capitellaspp, Cirratulidae,unidentified species "Tharyx parvus" ofBay authors! Cf enodri 1 us "serrat us Fteonecahfornica/Eteone 1ongacomplex [+] Euchone hmnicola Erogone "lourei" Fabriciasp. Glyceradibranchiata [+J Clycindesp. Harmothoeimhricata [+] Nc>eisvire»s [+J Page153 Cryptogenic Species

Table2. CryptogenicSpecies - continued

Polychaeta continued Oph ry at r ocha pverifi s Polydorasocialis Prionospiopinnata [+] Pygospioelegans [+] Spiophanesbo»rbyx [+] Spirorbidae,unidentified species Typosyllfs sp. Arthropoda:Crustacea Copepoda E«ryte>noraaffinis Notodelphyoidspecies commensal in the introduced seasc uirtMolgula! Cumacea C«»relfav»lgaris [+], in part;estuarine populations Tanaidacea Leplocheli a d«bia Caprella"eqr>ilibra" [+j Caprella"penantis" [+] Gra»difor«sgrandis = Paraphoz»s>nifieri af SanFrancisco Bay authors! Hyale sp. lschyroceridae,unidentified species List r'>el la s p. p!>otissp. Sy»cl>elidi»rn sp. Arthropoda: lnsecta Prckel>'sia>narginata on the introduced cordgrassSpartir>a aiterniflora!

Bryozoa AJcyonidi>rn>parasitic>»» Aspidelecira sp, ?! Co»ope«>nretie«l«>n Electracr«st»le»fa [+], in part: estuarinepopulations Me»>braniporasp. ?! S»>ittoideasp. Chordata: Tunicata Botryll»s "t»beraf»s* [+] D>der>r»»rr.sp. PagelS4

CHAPTER 5. RESULTS

A! TAXONOMIC GROUPS OF INTRODUCED SPECIES

In all,we documented 212species ofintroduced organisms inthe Estuary. Thenumbers of speciesper taxonomic group are presented in Figures 2 and3 at lowerand higher levels of aggregation.Invertebrates arethe most common major groupof introducedspecies, accounting for nearly 70'/o of the total, followed by vertebratesand plants with respectivelyabout 15 and 12 percent of thetotaL The mostabundant invertebrates were the 6'to of invertebrates! followed by molluscs0'10!, annelids 4'/o! andcnidarians 2'fo!. Nearly all thevertebrates were fish,and most of theplants were vascular plants, which were about evenly split between monocots and dicots. Thesenumbers are generally in accordwith our expectations prior to this study,based upon our knowledge of theEstuary's biota and consideration of other regionalreviews of introduced marine and aquatic species, with the exception ofthe numberof species ofvascular plants, which we had anticipated would be higher. Thisresult is in partdue to ourapplication of relatively more restrictive criteria for theinclusion of marsh-edge plants, as discussed inChapter 2. Pagel55 Results

For example,a studyof introduced speciesin theGreat Lakes using less restrictive criteriaproduced a listof 139introduced speciesof which59 species 2%!were vascular plants Mills et al., 1993!, and a similarstudy of the HudsonRiver produced a listof 154 introducedspecies with 97 3%! vascular plants Mills et al., 1995!. As suggested inthe "Methods"section, adding the plants in Appendix1 essentiaByterrestrial plants that havebeen reported in orat theedge of the tidaIwaters of theEstuary! to thelist of organismsin Table 1 producesa list of introducedspecies that can more reasonably be comparedto the Great Lakes and Hudson Riverlists, Thisexpanded list for the Estuary contains 240 introducedspecies of which49 0%!are vascular plants. These three and one otherstudy are compared in Appendix 5.

8! NATIVEREGIONS OF INTRODUCED SPECIES Thenumbers of speciesper native region are presented in Figure 4. Species weretreated as either marine or continental species, as shown in Table3, for assignmenttoappropriate regions. Nointroduced species were identified from the marineregions of the Eastern South Atlantic, the Western South Atlantic orthe EasternNorth Pacific, or from the continental region of Australia/New Zealand, so theseregions do not appear in Figure4. TheEstuary's marine introductions aredominated byspecies from the WesternNorth Atlantic accounting for 41% of allmarine introductions!, the WesternNorth Pacific3%! andthe Eastern North Atlantic 5%!. The Western NorthAtlantic provided mainly mollusks, arthropods andannelids, theWestern NorthPacific predominantly arthropods, followed by annelids,and the Eastern NorthAtlantic provided a few species from each of several groups. The Estuary's continentalintroductions aredominated byspecies from North America 4% of continentalintroductions; mainly fish! and Eurasia 9%, mainlyplants!. Resul ts Page 156

Table 3. Treatmentof IntroducedSpecies as Marine or Continental,for Analysis by NativeRegion

PLANTS Seaweeds marine Vascular Plants Spartirta spp. marine all othervascular plants continental

PROTOZOANS marine

INVERTEBRATES Annelida Ol i goch act a Braachiura sorverbyi continental Limrtodrilus mortothecus marine Parartais frici marine Patamothrix bavaricus continental Tubificaid es spp. marine Varichaetadrilus artgusti p crt ts continental Polychaeta Manayunkia speciasa continental all other polychaetes marine Cipattgopaludirta chinensis malleata con tmenta1 Melartoides tuberculata continental Carbicula flumirtea contin ental all other rnoUuscs marine Arthropoda: Crustacea crayfish continental all other crustaceans marine Arthropoda: Insecta Artisolabis maritima marine ¹ochetirta spp, continental Trigartatylus uhleri marine Entop roc ta Barerttsia bertedeni marine Urnatel la gracilis continental all other invertebrates marine

VE RTXBRATES Fish gobies marine Alosa sapidissima marine Mvrorte saxatilr's marine all other fish continental all other vertebrates con tin en tal Page757 ResutlS

c! TIMING OF INTRODUCTIONS

Analysesof thetiming of introductions,done with the intent to distinguish pulsesor patternsof invasions,are fraught with difficulties. In theSan Francisco Est ag'. as everywhere,larger and more conspicuous species such as certain crabs, fi». »d rnollusks!tend to be noticed relatively soon after their arrival, while smallerand more cryptic organisms may be present but remain unnoticed for scores ofyears until thearrival of an appropriately specialized biologist. For example, the Resu1ts Page 158

Bay'smud-dwelling worms received little attention until Olga Hartman began samplingin theBay in the1930s, and thus some of thepolychaetes derived from the Atlanticmight well have been introduced with Atlanticoysters! as early as the 1870s,The biasesintroduced by taxonomist-dependentrecords of arrival are not limitedto theearlier part of thiscentury. With enougheffort from appropriate taxonomicexperts, many species of tiny introducedorganisms such as protozoans, nematodes,flatworms and so forth couldcertainly be collectedtoday and identifiedfrom San FranciscoBay for the first time, althoughthey may have been in the Estuaryfor 100or moreyears. Given thesechallenges, we have,as notedin Chapter2, excludedfrom our tabulationsof the temporalpatterns of introductionsboth thosespecies whose only availabledates of first recordare the first written accounts,and thosespecies for which the date of first record seemsa clearartifact of the arrival or participationof an interested taxonomist e, g Olga Hartman in the 1930s polychaetes!,Eugene Kozloff in the 1940s symbiotic protozoans!, Willard Hartmanin the 1950s sponges!, and Ralph Brinkhurst in the 1960s oligochaetes!!,or an artifact of an especially focusedsampling effort e. g. the Albatrosssurvey of 1912-23,and our surveyof Bay fouling communitiesin 1993-95!,or simply the fortuitousdiscovery of a speciesin a restrictedhabitat or locality such as Transorchestiaenigrnatica, known only from the shore of Lake Merritt, and Lit torina saxatilis,known only from ten meters of cobblybeach in the EmeryvilleMarina!, and whoseinclusion would provide a misleadingview of the invasionhistory of the Estuary.These species are marked with an asterisk '! in Table 1. The datesof first recordwere tabulatedin five time periods four 30-year periods and one 26-year period! beginning in 1850.Tabulations of the datesof first record in the Estuary are shown in Figure 5, and of the datesof first record in the northwestern Pacific region in Figure 6. The results show a clear trend toward more first records in more recent periods. Over 40% of the first recordsof introductions in the Estuary date from 1970or later, and over 63%from 1940or later, Sincethe first recordsfor thenortheastern Pacific are inclusive of therecords for the Estuary,they necessarily averagesomewhat earlier; nevertheless,51% still date from 1940or later. Someof theseresults should be interpretedwith caution.The datesof arrival mustof courseprecede the dates of first record,by an unknownbut possibly significantaverage period. And althoughwe haveexcluded records that would causea specificand obvious temporal bias, there might exist a generalbias toward increasingnumbers of first records,which could be causedby suchchanges as an increasein samplingeffort, by the developmentof improvedtechniques for samplingand sorting, by a generalincrease in taxonomicknowledge, by anincreased availabilityand improvement of keysand other identification tools, or by other changes. On theother hand, several factors in theanalysis create a biastoward a lower numberof first recordsin the mostrecent period relative to earlierperiods. Thelength of themost recent period is a littleunder 26 years long, compared to 30years for theearlier periods. Extrapolating to 30years at thesame rate of productionof first recordsas has prevailed in theperiod so far wouldadd Page359 Resutts another9 species tothe recent period's tally for the Estuary, and 7 speciesto thetally for thenortheastern Pacific. ~ Whilea substantialnumber of firstrecords were excluded for the reasons discussedabove! from the third, fourth and fifth periods, virtually none were excludedfrom the first two periods. Someorganisms collected inthe most recent period but excluded from the list ofintroductions because of inadequate evidence to determinewhether they areestablished seeTable 8! will probably, with the passage oftime, be recogruzedas established.

~ Withthe passage oftime, the taxonomic problems thatbar the listing ofsome specieswill beresolved. There appear to be a substantialnumber of species thatwere only recently recorded from the Estuary that fall intothis category. Takingthese factors into account, it appears that the data signal a substantial pulseof invasions detected m the Estuary since 1970. The overall rate of introductionsto the Estuary12 speciesbetween ] 85pand ],995!averages one new speciesestablished every36 weeks. Inthe period since 1970, the dates offirst record indicatea rateof onenew species every 24 weeks even after excluding one-third of the212 documented introductions from the analysis, for reasonsdiscussed above!, Results Page160

D! MECHANISMS OF INTRODUCTION

Carlton 994! presenteda tabularoverview of globaldispersal mechanisms by humanagencies in fivebroad categories: ! Vessels;! Aquaculture,Fisheries, and Aquarium Industries;! Other Commercial,Goverrunent, and Private Activities; ! Scientific Research;and ! Canals.These have been reviewed in detail by Carlton979a, 1979b, 1985, 1987, 1992a! and by Carltonet al. 995!. Ourdata indicate that all of these mechanismsexcept for canalshave served to transport non- native speciesto the SanFrancisco Bay area.Within thesecategories, twelve mechanisms Table 1! and their approximate time of initiation relative to human- mediated invasions of the San FranciscoEstuary are summarize here a thirteenth mechanism, "gradual spread," accountsfor the arrival of a number of species, including muskrats,purple loosestrife,and watercress,all in the 20th century,that spreadeither naturally, by human activities,or both, from easternto westernNorth America!. We focus here primarily on those mechanismsthat serve to transport new speciesto the northeastern Pacific, rather than on intraregional vectors. The latter may include, for example, the intentional movement of fish between watersheds by members of the public with the intent of establishing new populations for sport fisheries or pest control such as the mosquitofish Garrtbusia!;the accidental movement of invertebrates in river gravels dredged for use as aggregatefor concrete such as the Asian clam Corbicula!,and the spreading of organismsby dredging activity such as the cordgrass Spartinaalterniflora!. No studies are available on the scaleor role of these within-system vectors. We note later that such work would be of great value in terms of both understanding dispersal potential and dispersal histories and in establishing management policies.

1. VESSELS

a nsi w d s The transport of marine organisms to San FranciscoBay by ships has been theoretically possible since the 16th century, when ships either traveling along the coast and passing by the entranceto the Bay, or making landfall on the shores of the gulf outside the Bay, could have releasedorganisms that made their way into the Bay. Thus, for example, Carlton & Hodder 995! have shown that vesselspassing the California coast in the 1570scould have releasedlarvae-laden hydroid palyps that could have drifted into the Bay. The first ship known to actually enter the Bay was the SanCarlos, on August5, 1775 Galvin, 1971!.By the turn of the 18thcentury a number of ships from the Atlantic and Pacific oceanshad entered the Bay Kemble, 1957!.After 1849,international shipping to the Baypicked up dramaticallydue to a combination of the California Gold Rush, the increasedexport of lumber, grain, minerals,furs, hides,and other productsfrom the rapidly developingindustries of central California, and increasedcolonization and industrialization in general. Kemble957! reviewsthe generalmaritime history of the Bay area- Page161 Resatfs

Little is knownof the modernrole of ship foulingin transportingmarine animalsand plants into San Francisco Bay, although there is evidence that this mechanismcould assume an increasinglyhigher profile due to thedecreasing use forenvironmental reasons! globally ofeffective antifouling paints such as those includingtributyltins TBTs!! A. Taylor, BHP Inc., Australia, pers. comm., 1995!. Theearliest clear records of shipfouling-mediated introductions though not recognizedassuch at the time! are the collections ofseveral North Atlantic fouling organismsinSan Francisco Bay between 1853 and 1860: the barnacle Balances irnprovisus853!, the hydroid Tubularia crocea 859! and the hydroid Sarsia tubulosa860! Table1!. Approximately 26percent of Bay invasions 5 species! havearrived by shipfouling and boring Figure7!.

In soli allast rock and t . carriedin a i 's ld Nohistory ofthe release ofships' solid ballast into the Bay Area is available. It presumablyparallels the general history ofshipping into the Bay, but source regionsfor rock and sand ballast, amounts released, and so forth remain tobe investigated. Thatrock and sand ballast may have played an early role is suggested bythe appearanceof the South African shore plant brass buttons Cotula coronopifolia! andthe Atlanticmarsh snail Ovatellamyosotis in the Bayin the 1870s Table 1!. Anotherexample of suchactivity was the release of ballastderived fram Chilean portregions such asIquique and Valparaiso! into the Oakland Estuary up until aboutthe 1920s, a transportvector that may have ]ed to the introduction ofthe southernhemisphere beach hopper Transorchesfia intonearby Lake Merritt. About 3 percentof Bay invasions species! are linked to this mechanism Figure 7!. It is Res uBs Page 162 probablethat this is an underestimate,and that with further studiesmore species especial]yamong non- arthropods, such as coastalinsects and spiders! will be found to have been ballast-transported, similar to the studies of Lindroth 957! on North Atlantic .

b lla w t Ballastwater may havebeen released into SanFrancisco Bay as early as the 1880s-1890s,but, as with solid ballast,the early history of ballastwater in the Estuary remainsto be studied. Of particularinterest would be data on the timing of increasedpulses of ballastwater release into theEstuary. Modern ballast patterns for selectedports within San FranciscoBay have been investigated by Carlton et al. 995!. In the Ports of Oakland and San Franciscoalone there were more than 2,000 arrivals of bulk cargo vesselsand petroleum product tankers in 1991. "Acknowledged"ballast water releasedfrom thosevessels in thesetwo ports exceeded130,000 metric tons approximately 34,000,000gallons! of water. "Unacknowledged"ballast water water that is on board but not recorded becausethe vesselis classifiedas being "in cargo"rather than "in ballast"! arriving in thesetwo ports is estimated at approximately an additional 130,000metric tons 4,000,000 gallons! Carltonet al., 1995!.Thus, more than 68 million gallonsof ballastwater per year are releasedby bulkersand tankersalone in the CentralBay area.Additional ports in the Bay system receiving large volumes of water include Sacramentoand Stockton, In 1991the Portsof Oaklandand SanFrancisco primarily receivedshipping fromother North Pacific ports. Shipping from Asiaaccounted for 26percent of ship arrivals in San Francisco and 48 percent in Oakland. Ships and thus water! also arrived from Central Pacific and South Pacific ports and, to a smaller extent, from the Atlantic and Indian oceans Carlton et al., 1995!. While somespecies may havebeen brought to the Estuaryin the first half of the20th century by ballastwater Table1!, thefirst reasonablyunambiguous signal of therole of ballastwater was the arrival of two Asianspecies, the shrimp Palaernonrnacrodactylus first collectedin 1957!and the Japanesegoby Triderttiger trigonocephatus first collected in 1962!,The arrival of both may have been associatedwith increasedtranspacific shipping related to theKorean War. Twenty- threepercent 8 species!of the Estuary'snonindigenous species are now linked to ballastwater transport, with a greatlyincreasing number of theseapparently having arrived sincethe 1960s Figure 5!. Thepulse of recentballast invaders into the Fstuaryis particularly evidentin the discovery,since the 1970s,of 15species of small Asian crustaceans copepods, one cumacean,one isopod, 3 mysids, and 2 amphipods!, and, since the 1980s,of two Asian clams Potamocorbufaand Theora!, oneJapanese fish Trr'dentigerbifasciatus!, and a New Zealandcarnivorous sea slug Phitine!.The appearanceof the Chinesemitten crab Eriocheirsinenst's in the Bay may also be linked to ballast water but see mechanism 11, below!. Results Page163

2. FISHERIESIMARSH RESTORATION AND BIOCONTROI. AcrlvITIKS a h'met fla ' te d a' a

The first Atlantic oysterswere plantedin SanFrancisco Bay in 1869,the year of the completionof the TranscontinentalRailroad. Early shipmentswere largely from New York and New Jerseyand occasionallyfrom ChesapeakeBay. The industrygrew and flourished in the 1890s,tapering off sharplyafter 1900 for reasons variouslycited as increases in pollutionand changes in the Bay'shydrology and flushingdynamics; see Carlton, 1979a!. The last oyster seed shipments occurred about1910, and adult oysterscontinued to be receivedfor holding in the Bay until the 1930s.Barrett 963! and Carlton 979a! review the history of Atlantic oystering in the Bay in detail. Thefirst Japaneseoysters were plantedout in the Ba.yin 1932,with plantings continuinguntil 1939.Occasional plantings for "experimental"purposes were started in the 1950s.Carlton 979a! reviews this brief and little-known history. The "signal"of Atlantic oysteringin terms of invasionsoccurred early, with the appearanceof the commonAtlantic soft-shelled clam Mya arenariain theBay by 1874 it was,oddly enough, not recognizedas such, and described as a newspecies!!. The Atlantic marshsnail Qvatellamay have also arrived with oysters,if not with ship'sballast, at this time.Coincident, however, with thegreatly increased pulse of plantingsin the 1890sof Atlantic oysterswas the appearancein the Bay of a variety of we/1-knownEast Coast clams and snails, including the oyster drill Urosalpinx 890!, the tiny gem clam Gemma893!, the marsh musselArcuatula =Ischadium! demissa894', two species of slipper Iimpets Crepidula convexaand plana 898, 1901!and the mudsnail Jlyanassa907!. Similarly, the Atlantic shell-boring sponge Cliona 891! and the common Atlantic pileworm Nereis succinea896! had been recordedby this time. Thirty speciesrepresenting about 15% of the introduced biota are now recogruzedas originating from Atlantic oystering activity. In concert with the much lower level of Japaneseoystering in the Bay, only a few speciesin the Bay are recognized as having arrived with this industry. After the pulse of 1.930plantings, the Japanesemussel Musculista 946! and the Japanese clam Venerupis philippinarum = Tapesjaponica! 946! were collected in the Bay. The immediate role of Japaneseoystering in transporting other speciesis not as clear, as many candidate taxa may also have entered the Bay by ship fouling or other means Table 1!. The Japanesebrown seaweedSargassum muticum, while apparently introduced to the Pacific coastby Japaneseoystering, may have entered the Bay as drift seaweedfrom elsewhere on the coast or, even more likely, as fouling on coastalship traffic. The Japaneseparasitic copepod Mytilicola may similarly have been transported into the Bay in mussels in ship fouling from more northern stations.About 4 percent of the Bay's invasions are linked to Japaneseoystering Figure 5!.

Fish or shellfish stocked b th overnrnent to establish or su fi he We review the early attempts to move Eastern fish West, facilitated by the completionof the TranscontinentalRailroad, in Chapter3. Americanshad, white Results Page164 catfish,several species of bullhead,and striped bass were all successfullytransported, released, and establishedin the Bay commencing in the 1870s.Intentional fish stockingby governmentagencies of freshwaterand estuarine fish into California and the Bay region has continuedto varying degreesthroughout the 20thcentury seediscussions in Chapter3!. Nineteenspecies 9 percent!of the exoticbiota owe their origins to this mechanism.

a a r t Plantingseither for marshrestoration or possiblyfor erosioncontrol were involved in the introduction of four speciesof the cordgrass Spartirtain the Bay in the 1960sand 1970s.One was plantedin Washingtonstate, and then transplanted from there to San Francisco Bay; another was likely introduced to Washington in solid ballast, and later independently introduced to the Bay from the Atlantic coast for marsh restoration; the third was introduced to Humboldt Bay in solid ballast, then transplanted to San FranciscoBay; the fourth, first reported in the Bay in 1968, presumablyarrived with an undocumentedrestoration or erosioncontrol project Chapter 3!. As we based our analysis on the mechanismsthat brought to the northeastern Pacific the stocks of organisms introduced to the Estuary, we counted three of these cordgrassesas introducedvia marshrestoration or erosioncontrol .4/0 of the exotic biota!, and one via solid ballast.

idental ea W ra i Accidental releasesof plants, fish, and invertebratesthrough stocking and planting programs began to be detected in the 1950sin the Bay region, although these may have occurred much earlier. Thus the rainwater killifish Lucartiaparva appeared in 1958on the Bay's margins, apparently having been releasedaccidentally with shipments of other fish in more eastern localities. The green sunfish and bigscalelogperch, as well as the curly-leaf pondweed, are additional accidental releases.Less than 3 percent of the Estuary's invaders comeunder this category.

aw ed a 'v bai W Miller 969! first described this mechanism focusing on lobster packing! as an active vector for transporting northwestern Atlantic marine organisms to San FranciscoBay. As discussedin Chapter 3 under the periwinkle Litforina saxatilis!, this mechanismcontinues vigorously today. Largequantities of Atlantic bait worms, and with them as packingmaterial Atlantic rocky shoreseaweeds mainly Ascophyllumnodosum!, are air-shippedweekly to sport-fishingsupply storesin the Bay Area. Investigations in progress Lau, 1995;Cohen, Lau & Carlton, in prep.! reveal that these seaweedssupport large numbers of living Atlantic coast invertebrates, including mollusks, worms, crustaceans,and insects, which are routinely releasedinto the Bayby anglers The apparentlyrecent appearance of the Atlantic red alga Callithamrtiottin the Bay, the establislunentof a populationof the Atlantic periwinkle Littorina saxatilis,and perhapseven the appearanceof the Atlantic green crab Carcinus maenasmay be linked to this active and unregulated Page165 Results flowof New England organisms to the Bay. To date, less than one percentofthe Estuary's invaders areclearly linked to this mechanism, butthe occasionalappearance of other species not yet known to bewstablished such as the Atlanticperiwinkle Liftorirta tittorea; Table 8! and the continual release of living seaweedsin the Bay which could themselves become established for example, Ascophyllumnodosum hasnow gained a foothold mthe Hood Canal, I'uget Sound; L.Goff, pers. comm., 1992!, predictably herald the imminent establishment ofyet additionalAtlantic species.

'oc ntr 1 rel B Invertebratesand hsh released for biocontrol in theBay region have been few, althoughtherelease ofmuskellunge andsea lions in San Francisco's LakeMerced to controlintroduced carp is a noteworthyincident in the history of human attemptsatbiocontrol Chapter 2!.Two South American weevils Neochetirta spp.! werereleased in the 1980s for water hyacinth control; these became established but appeartohave had little impact on these weeds Chapter 3!.An early introduction 922!to the state was the mosquitofish Gambusia affinis which arrived on Bay shoresatleast by the1960s if not much earlier. The inland silversides Menidia berytlina,brought tothe state for gnat and midge control in 1967, soon entered 971! Baywaters. These four species represent about two percent ofthe Estuary's exotic biota.

3. OTHER COMMERCIAL AND I RIVATK ACIVv'ITIES a Releases b an indiv'dual whether inte ' nal ar accidental RI Underthis mechanismwe includenon-government releases to establishfood resources the snail Cipangopaludina, theclam Corbicuta, the crayfish Procambarus ctarkii,carp, bullfrog, and perhaps the Chinese mitten crab Eriocheir sinensis and thepond slider turtle!; releases or escapesfrom residential ponds and aquariums plants and oligochaete worms with them!, possibly the snail Metanoides, goldfish, carp,and the turtle!; escapes from commercial breeding or rearingponds crayfish, carp,bullfrog! and discards of marketgoods the snailCipangopatttdina again!. Fifteenspecies representing 7 percent of the introducedbiota have been linked to this mechanismaccording to our data.With the possibleexception of carp,water hyacinthand Cipangopaludina,these have all been20th century activities.

4. SCIENTIFIC RESEARCH a Releases as a result of researchactivities whether inte tional o accidental R Scientificresearch efforts have resultedin relatively few introductionsto the Estuary.The bullfrog and- the virile crayfishboth owetheir establishment,at least in part,to releasesfrozn educational and research institutions in thelast half of this century.The green crab Carcinus maenas, as noted below, may be a furtherand more recentexample of this vectorI.ess than one percent of theEstuaries nonindigenous biota has arrived via this rnechanisrn. Results Pagel66

Thecomplexities andchallenges inanalyzing andproperly weighting these manytransport vectors, in termsof both developing anhistorical perspective and establishingeffective management options, isiHustrated bythe many species in Table1for which multiple transport vectors can be assigned. Therecent appearance ofthe Atlantic green crab Carcinus maenas inSan Francisco Bayis a superb illustrationofthe analytical andmanagerial hurdles involved. The green crab could havearrived by at least four different mechanisms Cohen et al., 1995!, whose relativelikelihood isdifficult toestimate. Asdiscussed inChapter 3,it may have arrivedin ballast water from any of several different source regions Atlantic America,Australia, Europe orSouth Africa, with the first two perhaps more likely basedon shipping patterns!; viaseaweed released from the bait worm industry; via activerelease from a schoolorresearch aquarium; orvia a ship'ssea chest or seawaterpipe system. Clearly, the control offuture invasions hinges on a clearer andmore detailed resolution of whichmechanism served to introduceCarcinus to theBay. Recent collections in the Estuary ofthe Atlantic amphipod Gammarus daiberi{1983!, the Atlantic worm Marenzelleria viridis 991! and the Atlantic snail Littorinasaxatilis 993! may point to the Atlantic as the source region for Carcinus {1989/1990!,andmay further suggest themodern resurgence ofan active Northwest Atlanticto SanFrancisco Bay transport corridor. Page167

CHAPTER 6. DISCUSSION

A! THEECOLOGICAL IMPACTS OFBIOLOGICAL INVASIONS INTHE SAN FRANCISCO ESTUARY Nonindigenousaquatic animals and plants have had a profoundimpact on theEstuary's ecosystem. Nohabitat w'ith the possible exception ofthe deep floor of theCentral Bay remainsuninvaded by exotic species, and in somehabitats it is difficultto find any natives. The depth and extent of biological invasions now recognizedforthe Estuary isgreater than for any other inNorth America,a phenomenon which apparently results from a combinationoffactors, including:150years of intense human commercial activity involving both the frequentdisturbance andalteration ofthe ecosystem andthe importation of nonindigenousorganisms Nichols etal. 1986!, the prior geological andecological historyof theBay, and the amount of researchinto biological invasions in this system.Despite the intensity ofresearch effort our understanding ofthe ecological andbiological consequences ofthe estuary's nonindigenous biota, in termsof both theindividual and the collective impacts of manyspecies, remains strikingly limited. A briefsurvey of the estuary reveals the scale of dominance bythe nonindigenousbiota. At theBay's mouth, under the shadow ofthe ,orange-red clumps ofthe Indo-Pacific bryozoan Watersipora, 30centimeters acrossand 20 centimeters deep, covers the dock sides. To the north, in SanPablo and Suisunbays, the Chinese clam Potamocorbufa forms thick beds in themud while Japanesegobies and Korean shrimp swim overhead. In a brackishriver a few kilometersdistant large, coral-like masses formed from the calcareous tubes of an Australianserpulid worm harbor an abundant population of the Atlantic shore crab Rhifhropa~iopeusUpstream in theDelta a Eurasianfreshwater hydroid forms thick colonieson ropesand marina floats. Swimming nearby may be any of several warrnwatergamefish native to eastern North America, including six species of catfish,four speciesof sunfishand four speciesof bass, Alongthe eastern and southern Bay shores, great masses ofAtlantic and Asianseasquirts comprise the dominant fouling biota along with dense populations of baymussels, represented in San Francisco Bay by both the native Myfilus trossulusand the Mediterranean Myfilus galloprovincialis. On thefringes of the Bay,dense beds of the New England ribbed mussel bind the upper intertidal sedimentsand lower marsh fringes, clonal colonies of theAtlantic cordgrass Spartinaalterniflora encroach upon the rnudflats, and a NewZealand burrowing isopodinexorably bores into the clay and mud banks of the Bay's shore Moving in seasonalmigrations over the mudflats, vast herds of theAtlantic mudsnail Ilyanassarework the uppermost layers of sedimentabove the subsurface beds of the Atlantic softshell clam and the Japaneselittleneck clam. With seasonalchanges, with dramaticinterannual variation in the amount of fresh~iater runoff or saltwaterintrusion, with the dischargeof point-sourceor Discrrssiort Page 768 diffuse pollutants,and with many other variables,these associations of introduced species may shift significantly, but the overall aspectremains the same:the dominant members of many of the Bay and Delta aquatic communities are organisms that were not present 150years ago. Considered here are the ecological and biological impacts that have been caused by the introduction of nonindigenous animals and plants into the marine, brackish,and freshwaterenvironments of the Bay and Deltaregion. We review examples of communities in which introduced speciesare the dominant members, both in termsof diversity and biomass,consider trophic changesin the Bay as a result of invasions,and then consideradditional community-leveland habitat changesthat have occurred. We conclude with prospectsfor future invasions. l. ASSOCIA11ONS OF NONINDIGENOUS SPECfKS Irr some regions of the Estuary, 100!o of the common speciesare introduced.

As Carlton975, 1979a,1979b!, Nichols k Thompson985a,b! and Nichols k Pamatmat988! have noted, the shallow-waterbenthos of SanFrancisco Bay is dominatedby nonindigenousspecies indeed, Nichols k Thompson985b! have used the phrase,"introduced mudflat community"in referenceto SouthSan FranciscoBay. Nichols and Pamatmat988!, in describingthe Bay'ssoft-bottom benthic communities, state that; "Theprincipal contributors to biomassthroughout much of thebay are the mollusks Tapes[now Venerttpis]philippinarttm, Muscufista serthottsia,Macoma balthictt [now pefafttm],Mya arenaria,Gemma gemma,and llyartassa obsoleta. In addition,the largetube-dwelling polychaeteAsychis [now Sabaco]elongata is a majorcontributor to total biomassin the muddy subtidalareas of SouthBay...[Since 1987] the Asian bivalve, Pofamocorbttla amttrensis.. has become the dominant macroinvertebratethroughout the northernportions of the bayand is found in South Bay sloughs as well." Eachof thesespecies is introducedto SanFrancisco Bay, arriving in the following approximatesequence: Time of First Observation !

Introducedwith AtlanticOysters Atlanticsoft-shell clam Mya early 1870s ! Atlantic tellinid clam Macorrta 1870s-1890s H! Atlantic gem clam Gemma before 1893 ! AtlanticmudsnaU Ilyartassa before 1907 ! Atlantic bamboo worm Sabaco after 1912 H! Introducedwith Japanese Oysters Japanesemussel Musculista before 1946 ! Japaneseclam Verrerupis before 1946 ! Introduced with Ballast Water Chinese clam Potamacorbula before 1986 ! Discussion Page169

Although thesenonindigenous species dominated the intertidaland subtidal rnudflatcommunities, many otherspecies of mollusks,crustaceans, polychaetes, and other invertebrateswere added to the Bay'ssoft-bottom communities during theseperiods as well Table1!. Eachnew additionor setof additionspresumably alteredthe previously-existingcommunity, in ways that may have preventedor facilitatedthe invasionof the next introducedspecies. While these"successional" conceptsof the rolesof inhibitionor facilitationby precedinginvaders are not well developedin invasionecology, the assemblyof thesecommunities over a relatively longperiod of time, from differentsource regions and thus of speciesthat did not coevolve!,may prove to be key factorsin understandingthe structureof invaded communities,and of which speciesdo and do not invade. A review of severalfaunal studies around the Bay conductedbetween the 1940sand 1970s Carlton, 1979a;Table 4, herein!demonstrates the importanceof introducedspecies in intertidalepifaunal on the surface!,intertidal infaunal under the surface! and foulingcommunities. In locationsranging from freshwatersites in the Delta throughestuarine sites in the northernbays, the CentralBay and the SouthBay, introduced species account for the majorityof the speciesdiversity at mostsites. On SouthBay mudflats,Vassallo 969! foundthat the infaunal communitiescould be characterizedin termsof introducedspecies: the upper intertidalwas essentiallya "Macornabatthica community," whereas the lower intertidalwas an "Ampetiscaabdita comrnuruty."At somesites, 100%% of the common to abundantspecies were found to be introduced.We discusslater in this sectionthe questionof the replacementor displacementof a nativebiota by these introducedspecies. Thus, extensivecommunities in the Bay are structuredaround introduced species:the abundantfilter feeders,the abundantherbivores, the abundant detritivores,and the abundantcamivores are not native.With few exceptions,the introducedversus native statusof the abundantprimary producers phytoplankton and algae!is not known, and thus the extent to which the entire food chain is constructedof invasionsis not yet known.However, few, if any, of the estuarine phytoplankton or algae are clearlynative. These communities are further composed of speciesoriginating from different regionsof the world speciesthat evolvedin the presenceof otherspecies that did not arrive with them in SanFrancisco Bay! and that evolvedunder differentenvironmental regimes, The extentto which these introducedspecies, artificially placed togetherin a novelenvironment, are undergoing coadaptation,in termsof predator-preyrelationships or competitive interactions, remains unknown. The predominanceof nonnativespecies in the Bay'scommunities suggest that a vastamount of energy,in termsof dissolvedorganic and inorganic compounds,and in termsof primary and secondaryproduction, now passthrough and are utilized by the nonindigenousbiota of the Bay. We exploresome of these trophic changesbelow, as well as the role of competition,habitat alterations, and the regionalor globalextirpation of nativespecies. Disc ussrart Page170

Table 4. Associationsof IntroducedSpecies in the SanFrancisco Estuary.

Thenumber and percentage ofintroduced species excluding cryptogenic species! in selected conununities,

Reference Location Numberof Introduced Species [dateof collections!

DELTA dc SUISUN BAY Antioch and Bradford 6 outof 7 =86%! epibenthic/fouling species are Aldrich, 1961 introduced,

Sacramento River, 3 outof 5 ~%%d!donunant benthic species are Siegfriedet al., DeckerIs. to ChippsIs, introduced. 1980 [1976!

Delta to Grizzly Bay 2 out of 4 =50'/o!dominant benthic speciesare Markmann, 1986 introduced. [1975411]

Suisun Bay 4 outof 7 =ST%%d!corrunon benthic species axe Nichols k introduced. Thompson,1985a Grizzly Bayto Old River 2 outof 5 =40%!dominant benthic species are Herboldk Moyle introduced. 1989[1983-84] Delta 26 out of 52 =50'/o!fish present, and 25 of 36 Herbold k Moyle, =69%%d!fish resident, m the Delta are introduced. 1989

Delta: Old River, Frank's 6 outof 22 =27%%u.!benthic invertebrate species Hymanson et al Tract and Sherman Lake are introduced. 1984 [1980-90!

Sacramento River at 10 out of 17 =59/a!benthic invertebratespecies Hymansonet al., Sherman island a re introducecL 1984[1980-90]

Grizzly Bay 16 out of 19 =84'/o!benthic invertebrate species Hymanson et al., are introduced, 1984[1980-90! SAN PABLO BAY San PabloBay east 8 out of 13 = 62%%d!epifaunal species,and 16out Filice 1959 to the Delta of 17 = 94'/o!infaunal species are introduced.'

Carquinez Stra it 7 out of 7 =100'/0!of commonbenthic species are Markmann, 1986 mtroduced. [1975-81]

SanPablo Bay shallows 9 outof 9 =100'%%d!common benthic species are Nichols ttr introduced. Thompson,1985a CENTRAL BAY Oakland Estuary All 4 species = 100/0!dominant in thefouling Grahamlk Gay, fauna are introduced.' 1945 [1940-42] Lake Merritt 31out of 35 = 88/o! epifaunal species, and 6 out Carl ton, 1979a of 8 = 75'/o!infaunal species are in [1962-72] Discussioa Page I71

Table4. Associationsof IntroducedSpecies - continued

Location Numberof IntroducedSpecies Reference [date of collections!

SOUTH BAY Hayward 4 out of 5 = 80'%!upper intertidal infaunal species Vassallo, 1969 are introduced.The infaunais numerically dominated by the introducedclam Macomapetafum; the epifaunais numericallydoaunated by the introducedmudsnail freya'tassobsofeta. 7 out of 9 = 7TA! lower intertidalinfaunal speciesare introduced.The commuruty is numericallydominated by the introduced amphipodAmpelisca abdita.

Palo Alto 14out of 14 =100'/a!species of mudflatinfauna Nichols, 1977 andepifauna are introduced. South Bay channels 10 out of 10 =100lo! commonbenthic species in the Nichols 4 channels, and 6 out of 6 =100'!o! dominant benthic Thompson9BSa! speciesin the shaHowsare introduced. For thesecalculations, all musselsreported asMytifus edufiswere assumedto be native.

2. TROPHlC CHANGES IN THE BAY hr the 1990s,introduced and cryptogenicspecies dominate the Estuary'sfood debs.

We consider here trophic alterations to the Bay'secosystem by introduced speciesutilizing differentfeeding levels and strategies: the phytoplankton,the zooplankton,water column consumers filter feeders!, epibenthic and shallow- infaunalgrazers and depositfeeders, and camivores.

Althoughvarious mechanisms have transported and continueto transport largenumbers of nonindigenousphytoplankton to theSan Francisco Bay andDelta todaymainly via ballastwater, but in thepast including settled diatoms transported with oystersand freshwaterphytoplankton in the waterused to transportg" fish!, and researchershave identified introduced diatoms and dinoflageliatesin otherareas of theworld in Australia:Hallegraeff, 1993; Hallegraeff and Bolch, 1992; in Europe:Boalch, 1994; in the Great Lakes:Mil1s et a]., 1993!,none of the phytoplanktonin theestuary have yet been reported as introduced species. We considerat least 31 species of phytoplankton tobe cryptogenic Table 2!, which is Discussion Page172 probably only a srnaHfraction of the total numberof planktonic,benthic, and epibiotic speciesthat havebeen irttroduced to the Bay and Delta system. The diatoms Cyclofellacuspia, Coscinadiscus spp., Autacoseira =Mefosira! spp., Aulacoseira =Melosira! disfans variety tirafa, Sketetonernacostafurn and Thalassiosiradecipiens and the microflagellate Chroomgnasminuta are dominant and important membersof the phytoplanktonin SanFrancisco Bay Cloernet al.,1985!.All arebroadly distributed globally and are cryptogenic species in San FranciscoBay. The diatom Autacoseiragranulata =Metosiragranulata, Round et al., 1990!has recently come to dominatephytoplankton blooms in the SanJoaquin River Herbold k Moyle, 1989!.In SuisunBay, the diatom Thalassiosiradecipiens alternatesbetween dominating the water columnor the ,apparent/y dependingupon the degreeof water columnmixing Cloernet al., 1985;Nichols and Pamatmat,19SS!. Both Aulacoseiragranulata and Thalassiosiradecipiens are cosmopolitanspecies e.g., Cholnoky, 1968! and may well be introductionsin the Bay system. Whilethese taxa are also often reported from open-oceansystems, including , the possibility remains that thesebrackish water and freshwater diatoms represent estuarine genotypestransported by oysters and ships around the world, and may be distinct from the oceanicgenotypes transported by oceancurrents. A similar example has been provided by Greenberg995!, who found that the estuarinepopulations of thejellyfish Aurelia aurifa in SanFrancisco Bay are closely relatedto thosefrom Japan and thus probableship-borne introductions as attached foulingscyphistomae or planktonicephyrae!, and less similar genetically to coastal populations from Monterey Bay. Thus,it remainspossible that manyof theestuary's major phytoplankton species,accounting for the bulk of the estuary'sprimary production,are in fact introduced.Resolution of thesecryptogenic diatoms as nativeor exoticwould significantlyimprove our understandingof the origin and structure of theBay and Delta'sfood webs; and is essentialto developinga correctinterpretation of their biology and their patterns of distribution and abundancein terms of, on the one hand,adaptation to andco-evolution with theestuary's physical conditions and otherbiota, or on the other,opportunistic establishment and exploitation of available resources.

Theplanktonic secondary producers are represented by a diversezooplankton communityin SanFrancisco Bay. Many copepod species in SanFrancisco Bay are consideredwidespread if not cosmopolitan,and thus those susceptible to human transportmechanisms should be consideredcryptogenic species. Notable in this regard,for example,are the abundantestuarine copepod Euryfemora affinis and the estuarinerotifer Synchaefabicornis, which oftencharacterize the zooplankton communitiesof the Sacramento-SanJoaquin Delta Orsi & Mecum, 1986!and whose biogeographicstatus remains unresolved. Euryfernora affinis in particularhas been suspectedof beingan introducedspecies Orsi, 1995!. Similarly, some microplankton in theBay are candidate cryptogenic species: the cosmopolitan estuarine ciliate Page173 Discussfan

Mesodirriumrubrum, for example,caused red in SouthSan Francisco Bay in spring1993 Cloemet al., 1994!. Whilethe diverse meroplanktonic larvae of thelarge numbers of introduced benthicinvertebrates and fish must play a rolein watercolumn dynamics, no studiesappear to be available on this aspect of zooplanktontrophic dynamics for the Bay.Mills and Sommer 995! have noted that the introduced hydromedusae Maeotiasirterspecfafa and Blackfordiavirginica in SanFrancisco Bay estuarine tributariesfed almost exclusively on barnacle larvae, copepods, and the larvae of the introducedcrab Rhithropanopeus. Whether these jellyfish decrease the abundance oftheir prey in anecologically significant manner remains to bedetermined. Maeotiasand Blackfordia are two of a largenumber of newinvasive zooplanktonic organismsthat have been recorded from the estuary since the 1970s, including anotherhydromedusan Cladonema uchidai!, the Japanese stock of themoon jelly Aureliaaurita, eight species of Asiancopepods, three species of mysidsand the demersal vertically migrating! Japanese cumacean Nippoleucon =Hemileucorr! hi rtumensis. Therole of this new guildof oftenabundant Asian copepods and rnysids in theupper estuary is of particularinterest, Complicating both speculations and interpretations,however, are the number and interrelationships of the potential factorsthat control copepod abundance. Changing densities and distributions of copepodsmay be correlated with fluctuationsin environmentalparameters such as salinity,temperature and chlorophyllconcentration!, predator abundance includingcarnivorous zooplankton, fish and benthicfilter-feeders such as the Asianclam Potamocorbula!capable of zooplanktivory!,selective predation on differentcopepod species, competition between copepod species the intensity of whichmay be moderatedby foodavailability!, and declinesin theoverall abundanceof zooplankton reducinginterspecific competition and making more food available!. Orsi et al. 983! speculatedthat competitionbetween the Chinesecopepod Sinocalar>usdoerri and. the "native" copepod Eurytemora affirtis considered here to be cryptogenic! was not likely becausethey preferred different salinity regimes; rather,competition and/or predationbetween Sinocalanus and the presumably native freshwater copepods Cyclopsand Diaptomus appeared to be more likely. Herbold et al. 992! noted that the introduction of Sinocalanusand Pseudodiaptomusforbesiiwas followed by a decline in Eurytemora and almost completeelimination of Diaptomus,implying potential interactionsbetween these new invaders and the previous copepod residents. Meng and Orsi 991! further found in laboratoryexperiments that the larvae of stripedbass itself an introduced species!selected Cyclops and Eurytemoraover Sinocalanus perhaps because of differencesin copepodswimming and escapebehavior!. Thus,the possibility arises that the stripedbass larvae's preferred prey is being replacedby an introduced,and lesspreferred, prey. A further complication, however, arises when the role of the newly introduced clam Potatrrocorbuiais considered, which involves both the consumptionof phytoplankton,thereby removing a significantportion of the potentialfood resourcefor water-columnzooplankton, and the consumptionof the Discussion Page 174 zooplanktonthemselves. Thus, as reviewed below, Kimmerer et al. 994! showthat the declinein Eurytemorawas likely due to consumptionby Potamocorbula,rather thanby interspecificcopepod competition. Indeed, Potamocorbula consumes Euryternoraand not Pseudodiaptomus Kimmerer, 1991!, further reducing the preferredcopepod resource of stripedbass larvae.

er d Introducedclams can filter the entire volumeof the SouthBay and Suisun Bay at leastonce a day.

A largenumber of nonindigenoussuspension-feeding organisms are now filteringthe waters of theestuary. In theintertidal and sublittoralsoft-bottom sedimentsthese include the introducedbivalves Macoma petalum ="balthica"!, Venerupis,Mya, Potamocorbula,Theora, Petricolaria, Gemma, Arcuatula, Musculista and Corbicula,most ot'which are abundantto extremelyabundant in the estuary.Introduced, suspension-feeding polychaete worms, especially spionids, and suspension-feedingtubicolous gammarid amphipods may occurby the thousands per squaremeter at and near the sedimentsurface. Intertidal and subtidalhard substratesare often thickly-coated,sometimes several organisms deep, with dense populationsof introducedmacrofilterers including the seasquirtsMolgula, Styela clava,Botryllus spp., Cionaspp. and Ascidia seeWhitlatch et al., 1995,regarding the complexroles of Styelnclava and Botrylloidesdiegensis, both introducedinto Lang Island Sound, in regulatingcommunity dynamics! and introduced microfilterers includingbryozoans and sponges!.Introduced carnivorous suspensionfeeders, such as hydroidsand seaanemones, can also be abundant:dense populations of the Indian Oceanhydroid Bimeriafranciscana occur on floatsin brackishtributaries, while the exoticsea anemoneDiadumene franciscana is sometimes found in dense clonal clusters on marina fioats on the southwestern shoreof the Bay. Bath doubtlesshave an impacton adjacentplankton communities. In some parts of the estuarythe Mediterraneanmussel Mytilus galloprovincialis and two introduced barnacles,Balanus irnprovisus and Balanusamphitrite, are exceedinglyabundant filter-feeders on all hard substrates. We consider in detail below the role of the benthicfilter-feeding bivalve guild in regulating phytoplanktonproduction in SanFrancisco Bay. The holistic role of the entire nonindigenousfilter-feeding guild clams, mussels,bryozoans, barnacles, amphipods, seasquirts,spianids, serpulids, sponges, hydroids, and seaanernones- in alteringand controlling the trophicdynamics of the Bay-Deltasystem remains unknown,The potentialrole of just one species,the Atlantic ribbed horsemussel Arcuatula demissa,provides insight into the potentiallyprofound impact of introducedfilter feederson the estuary'secosystems, Studying the energyflow in thesemussels in a Georgiamarsh, Kuenzler 961! reportedthat, "The rnussels...have a definiteeffect upon the water over the marsh, daily removingone-third of the particulatephosphorus from suspension.They regenerate a smallpart of thisinto phosphate, and rejectthe remainderin pseudofecesand feces which drop to themud Discussion Page175

surface.It appears,therefore, that the mussel population may be very importantin thephosphate cycle as a depositionalagent, furnishing raw materialsto deposit-feederswhich regenerate the phosphorus." Thepotential tantalizing role of Arcuatulain the economy of Bay marshes asa biogeochemicalagent remains to beinvestigated.

In two fundamentalpapers, Cloern 982! andOfficer et al. 982! demonstratedthat the primary mechanism controlling phytoplankton biomass duringsummer and fall in South San Francisco l3ay is "grazing" filter feeding! by benthicorganisms, in particular the introduced Atlantic gem clam Gemma gemma andthe introduced Japanese bivalves Musculista asMrrsculus! senhousia and Venerupisphilippinarurn as Tapes japonica!.> lfootnote onpage 2o9l Cloern982! calculated that "suspension-feeding bivalves are sufficiently abundantto filter a volumeequivalent tothe volume of South Bay af leastonce daily" emphasis added!. This remarkable process must have a significantimpact on thestanding phytoplankton stock in theSouth Bay; and with nearly the entire primaryproduction ofthe South Bay poten'tially passing through theguts of introducedclams, this may have fundamentally altered the energy available for native biota.

Th r l f t lan n'nN r an an > a nt u l e Pr tarn ula r Kichols985! extended this model of benthiccontrol of watercolumn productiontothe northern Bay. He noted that during the central California droughtof1976-1977, several species typically more common west of Carquinez Straitinvaded and became abundant in Suisun Bay including four introduced Atlanticspecies: theclam Mya arenaria which Nichols noted was introduced!, the amphipodsCorophium acherusicum andArnpelisca abdita, and the spionid polychaeteStreblospio benedicti. Inaddition, a resident species, thetellinid clam Macomabalthica now Macoma petalum, see Chapter 3!, increased in abundance; thisspecies toois introduced. Withthe arrival ofthese species andthe increase in Macoma,totalcommunity abundance peaked at153,000/m> atone site in 1976 and 20,000/m2atone site in 1977. During these two years, the usual summer diatom bloomfailed toappear Cloern etal. 1983!. Nichols 985! proposed thatthis guild of estuarineinvaders ledto increase benthic "grazing" filter feeding!, particularly by theclam Mya, but also by the other species Nichols noted, forexample, thatthe wormStreblospio switches from deposit feeding tosuspension feeding athigher phytoplanktonconcentrations!. Indeed,Nichols estimated thatMya alone "could havefiltered all of the particles including thediatoms! from the water column on d f~d "{ pd ' d Cloernet al. 983! noted that the presumably native phytoplanktivorous mysid opossum! shrimpNeomysis rnercedissuffered a "near-complete collapse"in theSuisun estuary in1977, which they describe inpart as a potentialresultof food limitation.Inturn, 1977 was a yearofrecord low abundance ofjuvenile striped bass Discussion Page 176

in the north Bay;larval bassrely heavilyon the mysid ¹omysis Cloernet al. 1983!. Both collapsesmay have been "a directconsequence of low phytoplanktonbiomass" Nichols, 1985!,which, if Nichols is correct in linking the decline of the phytoplanktonstanding stock to a risein benthicbivalve grazing, provides a direct and remarkableexample of the potentialimpact of an introducedspecies on the Bay'sfood web. Thus:

Populationsof the Atlantic Clam Mya arenaria

»SignificantlyReduces Phytoplankton Standing Stock

»Leads to a Declinein Zooplankton e. g. Mysids!

»Leads to a Declinein Fish e. g.Juvenile Striped Bass!

At aboutthe sametime 985! thatNichols first proposed that introduced clamscould be controllingprimary in SuisunBay, a ship inboundfrom Chinawas deballasting into Suisun Bay a speciesof clamthat would vastly overshadowthe trophicimpact of the existingguild of benthicphytoplanktivores. In October1986 three specimens of Potamocorbula amurensis, a species previously knownonly fromAsian waters, were collected in SuisunBay. By the following summer,Potamocorbula was the most abundantbenthic macro-organism in Suisun bay, achievingaverage densities of over2,000/rn2, and peak densities at somesites of over 10,000/m2.Potamocorbula has since spread and become the dominantsubtidal clamin SanPablo Bay and South Bay as well. Whathas been the impact of addingPotamocorbula to the Bay'secosystem? Alpineand Cloern 992! calculated that the mean annual primary production in SuisunBay during theyears of lowerbenthic clam density <2,000 clams/rn2! was 106grams of carbon/m2,compared toan estimated mean annual production of only 39grams/m1 when clams were dense >2,000 clams/m>; these clams were mainly Potamocorbula,but includedsome Mya, whosedensities declined sharply after the arrival of Potamocorbula Nichols et al., 1990!.Thus, since the proliferationand spreadof Potamocorbulain 1987,the summerphytoplankton biomass maximum in thenorthern estuary the diatom bloom! has disappeared, presumably because of feedingby thisnew invader. Thus since 1987, the invasionof the Bay by Pofamacorbulahas added a strikingand persistent "top down" level of controlto biologicalproductivity in theestuary. sternerand Hollibaugh 993! may haverecently provided the answerto one of thepuzzles associated with the radical alteration of theestuary by Potamocorbula: if thephytoplankton bloom has been eliminated by Potamocorbula's filter feeding, thenwhat are those billions of clamsnow eating? Cohen, 1990!. Werner and Hollibaugh showed that Potamocorbulaconsumes bacteria as well as phytoplankton,Though it consumesbacteria at lowerefficiency than diatoms, Page177 Discussion

Potamocorbulaassimilates both with highefficiency. At presentdensities in northernSan Francisco I3ay, ta a ' ' h wa u n v th da v rth hall w a m t 'rn a a rateof filtration which exceeds the phytoplankton's specificgrowth rate and approaches orexceeds thebacterioplankton's specificgrowth rate. Kimmereret al.994! have now provided evidence that Potamocorbula substantiallyreduces zooplanktonic copepod populations inthe North Bay by direct predation.Thus, Potamocorbula operatesat multiple levels inthe food chain: not onlydoes it reduce phytoplankton whichwould indirectly lead to reductions in zooplankton!,butit also directly consumes zooplankton. It willbe both critical to ourunderstanding ofthe trophic dynamics ofthe estuary and inordinately challengingtosort out the complex and changing interrelationships of a!these two levelsof Potamocorbula'sinteraction with the food chain, b! competitionbetween Potamocorbulaandother introduced and native benthic filter feeders, c! the roles of additionalfirst andsecond order consumers introduced to thezooplankton copepodsandrnysids! inreducing phytoplankton stocks, d!the role of interspecific competitionbetween and among introduced andnative copepods andmysids, e! selectivepredation byhigher order consumers, manyof them introduced fish species,on.the zooplankton, and f! competitionbetween and among both in.troducedand native higher order consumers. Invasions by new species of phytoplankton,zooplankton, andbenthic filter feeders inthe Bay invasions that canbe predicted with some degree of confidence Chapter X! willadd further complexitiesto this framework.

d E ibe thic and Shallow-InfaunalGrazers and ositFeeders Benthicnon-filter feeding invaders in SanFrancisco Bay include a number of carnivoresand ornnivores considered below! as well as epibenthicand shallow infaunalgrazers on surface sediments. The latter include a number of species of introducedpolychaetes such as the extremely abundant maldanid worm Sabaco! which actas selectiveor non-selectivedeposit feeders, interfacial bivalves such as Macomapetalum, which uses its siphonsto grazeon the mud surface but canalso suspensionfeed, grazing peracarid crustaceans including many introduced species ofamphipods, isopods, tanaids, cumaceans and mysids!, and the Atlantic mudsnail Ilyanassaobsoleta. Therecent discovery ofthe deposit-feeding Atlantic spionid Marenzelleria viridisin SanFrancisco Bay is ofparticular interest. Marenzelleria was transported by ballastwater to western Europe in the1980s and has since become one of the most commonrnacrobenthic species in theNorth and Baltic Seas Essink and Kleef, 1993; Bastropet al., 1995!. Preliminary studies reveal a varietyof speciesinteractions, in particulara significantpositive relationship between increasing densities of Marenzelleriaand increasing densities of Corophfum,although the mechanism of this interaction is not known Essinkand Kleef, 1993!. As withthe guild of filter feeders,the overallpicture of theimpact of introducedgrazers and deposit feeders in theSan Francisco Bay and Delta is not Discvss ion Page 178 known. Qasedupon Atlantic studies,however, it canbe predictedthat the mudsnail llyanassais playinga significant if not critical role in alteringthe diversity, abundance, size distribution, and recruitment of many specieson intertidal mudflats of SanFrancisco Bay. Millions of migratingmudsnails sweep large areasof mudflat clear of epibenthic diatoms OTC,pers. obs.,Barnstable Harbor, MA!, and Ilyanassahas further beenshown to be an opportunisticomnivore, consuming spionid worms and littorinid snail egg cases Brenchley k Carlton, 1983!.

r v I a iv an V "... the arrival and establishmentof the greencrab signals another potentially exceptional level of ecosystemchange in SanFrancisco Bay..." Cohen et al, g995!

".. Carcinusmaenas will significantly alter communitystructure, ecological interactions, and evolutionary processesin embaymentsof western North America" Grosholz & Ruiz 995!

Introduced carnivorous and omnivorous crabs, snails, fish and terrestrial mammalsundoubtedly have broad impactsthroughout the SanFrancisco Bay and Delta ecosystem.Smaller introduced carnivores are now present and often abundant!throughout the Bay. Theseinclude on soft sedimentsthe recently introduced clam-eating slug Philineauriformis from New Zealand; on rocks and pilings the Atlantic barnacle-eatingoyster drill Urosalpinxcinerea; and in hydroid masseson floats and navigationbuoys the largeJapanese isopod Synidotea laevidorsalis.We consider here and in Section5 below!three categoriesof carnivorous invaders in the estuary: the European green crab Carcinus maenas, introduced anadromous and warmwater gamefish, and introduced mammals, The potential and observed roles of Carcinusmaenas, first collected in California in 1989-1990in the EsteroAmericano and in SanFrancisco Bay, have beenaddressed at lengthby Cohenet al. 995! andby Grosholz& Ruiz 995!, the essenceof whosefindings havebeen quoted above. Cohen et al. 995! noted that Carcinusconsumes "an enormousvariety of prey items,"including organisms from five plant and protist phyla and 14 animalphyla. They predict that Carcinuswill prey on many of the previously introduced speciesin San FranciscoBay both epifaunaland infaunaltaxa with the clamPotarnocorbula being a potentialmajor prey item. Carcinus'habitat rangeincludes marshes, rocky substratesand fouling communities, and the European and New England literature indicates broad and striking potential for this crab to becomean importantcarnivore in thesesystems Cohenet al., 1995!.Grosholz & Ruiz 995! report that Carcinushas already "significantly reduced densities" of the most abundant near-surfacedwellers in BodegaHarbor, 75 km to the north of San Francisco.These taxa included the native bivalvesTransennella spp., the cumaceanCumella vulgaris and the amphipod Corophiumsp. In laboratoryexperiments, Carcinus captured and consumed Dungenesscrab Cancermagister! up to its own size. Page179 Discussi an Thetwenty~ight species ofintroduced anadromous, freshwater oreuryhaline fishin theestuary include many important carruvores nowfound throughout the upperestuary. Qlparticular, carp,rnosquitofish, catfish,green sunfish, bluegill, ands>!verside, largemouth and smallmouth bass, and striped bass have been foundto be among the most significant predators throughout thebrackish and freshwaterreaches of theDelta. Of particularconcern isthe extent to which these introducedfish have reduced populations orcontributed to the local or global ctionof nativeCalifornia fish. Evidence for interference,reduction, and destructionofspawning andnursery sites of native species, andthe extirpation of nativefish from feeding grounds, has been found for introduced carp, catfish, green sunfishand bluegill.

3. SPATIALPATTERNS OF COMPHTTION Little is knownof pre-1850Bay and Delta ecosystems by whichto determine thediversity and density ofthe aboriginal aquatic biota, and thus assessments of whetherintroduced species replaced or displacedabundant native organisms are severelyconstrained. Stimpson 857! implied though he may have been speaking of echinoderrnsonly! that the invertebrate fauna of the Bay was depauperate inboth speciesand numbers of individuals, although it is possible that even by Stirnpson's time thevirtual eliminationof a top levelpredator theaboriginal Indian population!in theBay Area had led to a top-downcascade offaunal changes; orthat theelimination of a keystonespecies controlling habitat structure in thewatershed beaver!,acting through effects on anadromousfish populations, could have similarlyinitiated a cascadeeffect McEvoy,1986!. Nevertheless, despite the limitationson our knowledgeof the Estuary'snative fauna, it is clearthat in certain habitatsthere were no nativespecies in sometaxonomic groups and trophic guilds. Table5 showsthe patternsof spatialrelationship between native and introducedinvertebrates along the marineto freshwatergradient in the Estuary. Thesepatterns suggest that at least for someinvading species, resources were availablethat were not beingcomparably utilized by native taxa,perhaps facilitating the initial invasion and establishment of the exotic species. The terms "open niche," "empty niche"or "vacantniche," sometimes applied to suchsituations, are misnomers, A "niche" refersto the living conditionsof an existingspecies, not to imaginaryecologic space, open or otherwise;see Herbold k Moyle,1986.! Themost common spatial pattern of invasionin theEstuary is for introduced speciesto occupy regionspartially or whollyupstream of their apparentnative counterpartspecies. These introduced and native counterparts may coznpete where theirranges in theEstuary overlap, but in manycases in at leastpart of itsrange, the introducedspecies is freefrom such competition. An exampleis theintroduced Atlantic crabRhithropartopeus harrisii which exists in the upperBay and Deltaat salinitiesbelow' the 3 ppt tolerancelimit of the native crab Hemigrapsus oregonensisln turn however,Hrmigrapsgs through predation and possibly throughcompetitive interactions, may limit Rhithropanopeus'downstream expansion Jordan, 1989!, Discussion Page180

Table$. patternspf invasionAlong the Salinity Gradient in theSan Francisco Estuary and the AdjoiningCoast

Nativespecies are listed in normaltype. Invading species are listed in boldtype.

Marine M esohaline Oligoha line Fresh

PATTERN: UPSTREAM INVADERS

Micraciana microjoanna Microcianapralifera None None

Ha 1ichandria panicea Ha lich andria None None botverbanki

Metridium senile Metridiurn senile? None None Diadumenefranciscana Di ad«mene ?cincfa Diadumene leucolena Diadumene lineata

Serpu la 'vermicularis Ficopomatus Ficopomatus None enigma tic«s enigmaticus

Crepidu1anummariaa Crepidulaplana None Crepiduia perforansa

Crepidu1a adunca Crepidulaconvexa None None

Oceneb ra ci rcum t exta Urosalpinrcinerea None None Ocenebra lurida

Mytitus cah%rnianus Mytilus trassulus None None Mytilus gallapravincia!is

Ce~Q.~ Trans ennel la canfusa Transennella tanti11a ? None None Transennel1a tan tilla Gemmagemma

Protothaca starr.inca Protathaca staminea None None Venerupis phi li p pina rum Page181 Discussion

Table5. PatternsofInvasion Along the Salinity Gradient - continued

Oligoh aline Fresh Marine Mesohaline

Macorrra petalurn None Macorna secta Macoma nasuta Macoma inquinata Macomapetalunr Macorna nasuta

~!~w~ None Bankia setacea Teredo navalis Lyroduspedicellatus Teredo rravalis

Balanus improvisus Balanus rrnprovrsus Balanus crenatus Balanu s g!and u la Batarrusglarrdula Balarrvs rmprovrsus

Cirolana harfordi Eury anaarcuata None None

d-ain I I Synidoteabicuspida Synidotea None None Synidotea ri t teri 1 aevid or s ali s

~a'i~ Lcp tochelia d ubia» S inelobus sp. hlgsLi~ab: Hemigrapsus»udus Hemigrapsus Rhithropanopeus Rhithroparropeusb harrrsrr Herrrigrapsus oregonensis harrrsrr orego»c»sis

~r~ Barerrtsia graci 1is Barerrtsia benedeni None Urnatella grac!lis

tB o ansinthe Bu 1 Bugula californica Bugulaneritrna None None Bugula pacr'fica Bugulastolonr'fera Bugula neritina

obran a u' Ascid ia ceratodes Ascidia sp. None None Coreillasp. Crona intestirralis Chelyosornaproducturrr Ciona savignyi

1 t liclob a Styela truncata Styela montereyensis Molgularrranhattensis None Styela mo»tereyensis Styela clava haustor Molguta manhattensis Di scussion Page I82

Table S. Patternsof InvasionAlong the SalinityGradient - continued

Marine Mesohaline Oligohaline Fresh

Gahea Clevelondia ios Clevelandia ios Eucyclogobius Tridentigerbifasciatus Coryphopterusnicholsii Euryclogobius neroberryid Acanthogobius rreroberryid Lepidogobiuslepidus flavirnanus Lepidogobius lepidus Tridentigerbifasciatus Tridentiger Ar anthogobius trigonocephalus flavimanus Gill ichthysmirabilis Aranthogobius flavimanus

PATTERN: INSERTION INVADERS

Nereis vexillosa ¹reis succrnea Nereis succinea Hediste limnicola

PATTERN: DOWNSTREAM I NVADERS

Corophium acherusicumCorophiumspinirorne Corophiumspinicorne Corophi um alienense Corophiurn stimpsoni Corophium stimpsoni Corophium insidiosum Corophiurnacherusicurn Corophium Corophium alierrense he te race ra turn

OTHER PATTERNS OF IN VAS! ON

None Pal aemon Palaemon None macrodactylus macrodactylus

None Cerithidea calijornira None None Jlyanassaobsoleta e

None Assimirreacalrfornica Assimirreacalifornica None Ovatellamyosotr's i Ovatellamyosotis i Discussion Page183

Table5. PatternsofInvasion Along the Salinity Gradient - continued

Marine Mesohaline Oligohaline Fresh NO INVADERS WITH POTENTlAL FOR INSERTION INVADERS!

Gno rimosphae rom a Gh orirhosp ha ero Fna Ntxx.g GhorimosphaerOma oregonense oregonchse insulare

Anisogammar «s Anisogamrna rus None Antsogammarus confervicolus confervicolus ram rllus

Crepidulanummaria and perforans may not be separate species. Regularlypresent but not reproducing. Cryptogenic, Formerlypresent, now extinct frozn the Estuary. Race982! demonstrated thatcompetitive andother interactions sortthese snails along a salinity/e]evationgradient by mid-summer Berman8zCarlton 991! found little competitive interaction between these snaUs in Oregon Themarshes,introduced Japanese estuarine isopod, Gnorimosphaeroma rayi,is reported from Tornales Bay northof San Francisco!, butis not yet known from San Francisco Bay.

Othernotable "upstream invaders" include the Atlantic barnacle Balartus improvisus,themost freshwater-tolerant barnaclein the world, whose range inthe Estuaryextends farupstream ofthe Bay's native barnacles; twoJapanese gobies, Aca~ttItogobiusflavirnartus and Tridert tiger bifasciatus, which have become abundantin the upper Bay and Delta upstream ofthe native estuarine gobies, and havebeen transported south from the Delta in freshwater irrigation canals; the Australianserpulid worm Ficoporrtatus ertigrrtaticus, theonly tubeworm found in thebrackish parts of the Bay and extending intoquite low salinity water; and the shipwormTeredo rtavalis, which when it was introduced inthe 1910s invaded upstreamportions ofthe Estuary notpreviously entered bythe Bay's existing native andexotic shipworms, andcaused enormous damage towooden maritime structures.Insome cases, such as that of the freshwater entoproct Ur7trrtella gracilis, theintroduced species maylive in such low salinity water that it never overlaps in rangewith its closestnative, and more marine, counterparts. A secondspatial pattern, rarer and perhaps more difficult foran exotic species tosuccessfully achieve, isthat of an "insertion invader." Anexample wasdescribed byOglesby 965!, who pointed out that among nereid worms theintroduced brackishwater worm Nereis succirtea occupies a geographic position in theestuary .eentherange ofthe native marine worm Nereis vexillosa andthe range ofthe nativefreshwater worm Hediste limrticola. He arguedthat succirtea, being more finelyand narrowly adapted tothe brackish water ecotone, mayoutcornpete the DiscusSion Pagel84

more broadly adaptedvexillosa and limnicolawithin this zone. A third spatialpattern in theEstuary, uncommon and somewhat unexpected, is the "downstreaminvader" mode exhibited by the introducedamphipods in the tube-buildinggenus Corophium. John Chapman has suggested that thenative Corophiumspecies may have beenadapted to a specificflow and sedimentation regime,and that the dramatichuman alteration of theseparameters due to hydraulicmining, soilwroding agricultural practices, construction and roadbuilding, and the leveeingof channelson the one hand, and dam constructionand water diversionson the other! that has occurred since the mid-19th century may have facilitatedthe invasion of the Estuaryby at leastthree species of morernarine- adapted Corophium. Otherspatial patterns of native-invadercompetition are alsorepresented in the Estuary: ~ In thecase of thebrackish-water, fouling-inhabiting Korean shrimp Palaemonmacrodactylus, there are no apparentnative counterparts, upstreamor downstream,and thus no obviouscompetitors. The native marsh snail Assimineacalifornica and the Atlantic marsh snail Ovatellamyosotis, occur in thesame marsh areas and appear to be counterparts,but studiesin Oregonon thesetwo snails found little evidence of any competitiveinteractions between them Berman& Carlton, 1991; whilein the Estuarythese snails apparently co-occur over their whole elevationalrange, in Oregonthey co-occur only in thelower part of Ovatella's elevationalrange!. ~ Theintroduced Atlantic snail?Iyanassa obsoleta now occupies the Bay mudflatareas formerly occupied by thenative snail Cerithidea californica. Eachspring the two populations of these snails collide, and by rnid-summer theexotic flyanassa restricts the native Cerifhidea tohigh-marsh salt pannes an environmenttoo high in salinityfor llyanassa and thus providing a habitatrefuge for Cerithidea! through egg-string predation and direct competitiveinterference Race,1982!.

Along with competition, other interactionsbetween native and introduced speciesmay also occur, potentially leading to changesin cornrnunityor habitat structure, or to the replacement,displacernent or local eliminationof the native taxa. Examplesare reviewedin the sectionsbelow.

4. COMPETITIVEINTEIIACT1ONS AND HABITATAITERATIONS At theend of the20th century, exoticspecies play a majorrole in structuring or altering aquatic environments.

We have consideredabove the evidencefor dramaticalterations in the food websand energy flow in the San Francisco Bay and Delta ecosystem due to individualspecies and species guilds. With such evidence inhand, it is easyto overlookthe fact that for many abundant species in the Bay and Delta, little or nothingis known about their ecological roles trophic or otherwise in the Page285 piscussion ecosystem.Forsuch common introduced species asthe marsh plants brass buttons Cotufacorortopifotia! andpeppergrass Lepidium latifolium!, many of the freshwaterfish, the mat-forming mussel Musculista, the bed-forming mussel Mytifusgaltoprovincialis, thesoft-shell clamMya, the littleneck clam Venerupis, andmany of the introduced polychaetes, crustaceans, hydroids, seaanemones, tunicatesand bryozoans, little or nothing isknown of their competitive and potentiallyregulatory interactions withnative species and with each other. Certamobservations andexperimental data are available, however, both in theBay and elsewhere, togain some insight into the additional extensive community-levelmodifications thathave taken or may be taking place through competitiveandother interactions ofnonindigenous species.

a oft-8 'ttarn C unit'e In subtidaland intertidalsoft-bottom communities, dense beds > 2,000 individuals/m2!of Potamocorbulaamurertsis appear to havemechanisms that preventthe successful establishment ofother organisms, native or introduced. Thesemechanisms may include predation on the larvae of theseorganisms, more efficientfilter feeding Nichols et al. 1990!and direct spatial competition. In theonly experimental studies done to datein SanFrancisco Bay on the interactionsbetv een benthic native and introduced invertebrates, Race 982! has shownexperimentally thatthe introduced rnudsnail Ityanassa obsoteta restricts the nativernudsnail Cen'thidea californica to upperintertidal, high salirutyhabitat throughegg predation and direct interference.

Foulin Co unities Competitiveinteractions in Bay and Delta fouling communities canbe inferredfrom studies of thesame or similarspecies in othersystems; the absence of suchwork in SanFrancisco Bay is notable.Working in nearbyBodega Harbor, Standing976! experimentallydemonstrated that the hydroid Obetia "dichotoma", alsopresent in SanFrancisco Bay, decreases thesettlement rate of barnacles but increasesthe settlementrate of ascidians.By interferingwith barnaclerecruitment, ascidiansettlement is enhanced,and dense aggregations of ascidianssupport a diverseassociated community. Working in NorthCarolina, Sutherland 977, 1978! foundthat the bryozoan Schizopor ella sp. identifiedas S. unicornis but perhaps not thatspecies! and the seasquirt Styela plicata introduced from the Pacific to the Atlantic,although this was not known to Sutherland! have a stabilizingrole in communitystructure: when dense, these two dominant species exclude other speciesfrom invading, resulting in patches with fewer species and less change over time.On a greatertime scale, however, Styela destabilizes the fouling commuruty throughannual "sloughing off' of thelarge summer individuals, taking the associatedfouling community with it. BothSfyela species and Schizoporefla unicornisare common in SanFrancisco Bay. Sutherland's observations mav further aid in explainingthe apparent replacement of musselbeds Mytitusedulis! in parts of NewFngland by theintroduced Asian seasquirt Styela clava, a speciescommon throughout the Bay's fouling communities.

Discussion Page187 e Bi-roder I theBa ar i 'a e Someevidence exists that bio-erosion of the Bayand Delta land marginsmay beoccurring atthe "hands" ofburrowers and borers among the exotic fauna. The introducedcrayfish Procambarus clarkii excavates burrows 5 crnin diameterand as muchas 100 cm deep in Deltalevees and banks. Muskrats similarly create extensive burrowsystems inthe Delta. The recently introduced Chinese mitten crab Eriocheir is knownto formextensive excavations along river banks. However,the most numerous bio-eroder around the Bay margins is theNew Zealandboring isopod Sphaeroma quoyanurn. Carlton 979b! has described portionsofcertain eastern and northern bay shores, characterized bymany linear metersof fringingmud banks riddled with theone-half centimeter holes of this isopod,as"sphaeroma topography," a phenomenon illustrated byBarrows 919! andHannon 976!. Higgins 956! concludedthat this isopod plays "a major, if not thechief, role in erosion"of intertidalsandstone and tuff terraces along the south shoreof San Pablo Bay, due to boring activity that weakens the rock and facilitates its removalby waveaction. Hannon 976! reported one estimate that Sphaeroma could"remove up to 10meters of dikein oneyear", a numberthat appears excessive.Nevertheless, Sphaeroma has been burrowing into bayshores for overa century,and it wouldnot be surprising tolearn that the land/water margin has retreatedat certainsites by a distanceof at least several meters due to thisisopod's activities. Exceedinglyvaluable would be observational andexperimental studies in the Estuarythat focus on the erosion rates of crayfish,muskrats, isopods and, if they becomeabundant along channel, stream and river banks, Chinese mitten crabs.

5, THE REGIONALAND GLOBALEXTIRPATION OF NATIVE SPECIES No estuarineor aquaticintroduction in theSan Francisco Bay region has solelyor indisputablyled to theextinction of a nativespecies. Short of this, however,invasions in the Bayhave led to the completehabitat or regional extirpationof species,have contributed to one global extinction of a California freshwaterfish, and are now strongly contributingto the further demiseof endangered marsh birds and mammals. a Introduced Fish and th xti ation of Native Fish Introducedfreshwater and anadromousfish have been directly implicatedin theregional reduction and extinction, and the global extinction, of four native Californiafish. The introduced striped bass, largemouth and smallmouth bass, bluegilland greensunfish, through predation or throughcompetition for foodand breedingsites, have all beenassociated with the regional elimination of thenative Sacramentoperch from the Delta.The introducedinland silversidemay be a significantpredator on the larvae and eggs of the native Delta smelt. Expansion of the introduced smallmouth bass has been associatedwith a decline m the native hardhead.Predation by stripedbass, largemouth and smallmouth bass may have beena majorfactor in the globalextinction of the thicktail chub. Discussion Page 188

d e a r d al' er Rail: a at and Foxes u . ab' The Californiaclapper rail may serveas an exampleof how populationsof an alreadyendangered species may be further threatenedby biologicalinvasions. Despite the interest in clapper rails in San FranciscoBay, however, there has been little quantitativeinvestigation of the impact of introducedspecies, suggesting fruitful avenues for investigation. Norway rats, establishedin many areasof California by the mid-1880s, have long beenrecognized as significant predators on clapperrail, starting with early observationssuch as the following de Groot, 1927!:

"the clapper rail has no more deadly enemy than this sinister fellow. No rail daresnest on a marsharea which hasbeen dyked, for as surely as she does this vicious enemy will track her down and destroy the eggs,Many nests have I found bearing mute evidenceof the fact that someluckless rail had gambledher skill at nest-hidingagainst the cunning of the Norway rat, only to have her home destroyed."

Predation on both rail eggs and rail chicks is considered to be high, with as many as a third of rail eggssaid to be taken by rats Oosselyn,1983; BQDC, 1994!.The cordgrasszones of salt marshessupport the highestclapper rail densitiesby providing coverand/or isolationfrom rats, raptorsand feral predatorsOosselyn, 1983!,and thus the expansionof thesezones by the introducedAtlantic cordgrass Spartiiiaatternrflora could benefit rails. Alternatively, competitive replacementof native cordgrassby S. alterniflora could reduce preferred cover for the rails. Although present inland in California since the 1870s,the red fox has appearedon the marginsof SanFrancisco Bay, adding another critical clapperrail predatorto the ecosystema centuryafter the appearanceof the Norway rat. In California the red fox haspreyed on the eggsand sometimesthe young or adults, anddisrupted nests or colonies,of theclapper rail aswell asother birds, including least , snowy plover, Caspian tern, black-neckedstilt and avocet! Forester & Takekawa, 1991;Takekawa, 1993; BDOC, 1994!. Reductionin clapperrail populationsby exoticspecies through processes other than direct predationmay alsohave occurred.De Groot 927! reported,under the headingof "the invisible foe," the following concerningthe relationshipof adult rails to the Atlantic ribbed marsh mussel Arcuatula demissa;

"This apparently harmless little mussel has been another of the rail's most relentless enemies, and the number of rail deaths attributable to its activities is incredible...Countless millions of these small mussels cover the edges and sometimesthe entire bottoms of the gutters and creeksof the west Bay marshes.Up under the banks,where the rail so commonly feed and hide when the tide is out, these death traps are foundin greatnumbers...Along comes a railgingerly pecking into the Page189 Discussion softmud and it! rams its! beak into the open mussel and in aninstant thetrap is sprung and the rail is helplessly andhopelessly trapped... shakingandscraping andpulling are all in vain... and!thepoor rail eventually dies! by starvation" DeGroot further believed that "at least seventy-five percent" ofthe adult rails ofthe Redwood marsh area in the South Bay had lost toes by entrapment inmussel shells.He argued that this led to the loss of juvenile birds as well: "Butwhile the adult rail generally escapes with merely the loss of a toe ortwo, young birds must meet death frequently... is! theresome basis forstating that probably one or two chicks inevery brood, if not more, meetan untimelyend in thismanner..." Morerecent observers note that clapper rails in the Bay are frequently missing oneor more toes Moffitt, 1941; Josselyn, 1983; Takekawa, 1993! and Josseiyn 983, p,69!includes a photograph ofan adult clapper railmissing onetoe and with an Arcuatula clampedto another. Unfortunately,accurate quantification ofrail:mussel interactions islacking, andthus the impact implied byde Groot tobe approaching one-third brood mortalityatthe valves ofthe mussel! onclapper rails remains unknown. Thatthe rail/musselinteraction may not be all one sided, however, issuggested byMoffitt's 94l! studyof rail feeding, wherein he found ina sampleof18 birds that 66 percent of theanimal food of therail and57 percent of thetotal food! consisted of Arcuntula.

c Other Exam les of Red ions and xt' ations Aroundthe Bay and Delta, reduction and elimination ofpopulations of other nativespecies have occurred orappear tobe in progressasthe result of interactions withintroduced species, Unfortunately, aswith impacts onthe clapper rail, and ~iith thesole exception ofimpacts on native snails, no quantified data appear tobe available.It has thusbeen suggested or observedthat: ~ the introducedAtlantic mudsnail Ityanassa has displaced from rnudflats to saltmarshpannes and reduced the population ofthe native znudsnail Cerithidea, ~ introducedgreen sunfish, bluegill, largernouth bass and the introduced Americanbullfrog may have contributed tothe decline ofnative red-legged andyellow-legged frogs in the Bay and Delta region, largely through predation; ~ introducedred fox, through predation, reduce or limit the recovery of populationsof the endangeredsalt-marsh harvest mouse; ~ introducedcrayfish have displaced some native crayfish species and threaten others; ~ introducedpeppergrass Lepidium latifolium! may displace rare native marsh plants, such as Littaeapsismasoni. Discussion Page 190

B! THE ECONOMIC IMPACTS OF BIOLOGICAL INVASIONS IN THE SAN FRANCISCO ESTUARY

The economicimpacts of introducedmarine, estuarine and aquaticorganisms havebeen little studiedand rarely quantified.It is clear,however, that theseimpacts have been substantial in the San FranciscoEstuary. Theseimpacts are of severalinterrelated and intergradedtypes. Positive impactshave includedthe value of food resourcesand recreational sportfishing! resourcesprovided by someintroductions of fish and shellfish;the biological control of nuisanceinsect populations e. g. by mosquitofish!; and fish and wildlife enhancementssuch as the provision of food, habitat or other resourcesfor valued species Table 6!. Major negative impacts have included the fouling and blocking of waterwaysand water delivery systems;damage to or impairmentof maritime structures and vessels e. g. damageto wharves, docks, ferry slips and ships' hulls by marine wood-boringorganisms; increased fuel and maintenancerequirements resulting from hull fouling!; disruption or impairmentof vital services;damage to populationsof economicallyimportant fish and wildlife species;the costs both direct and indirect! of control efforts; and the inability, in the face of continuoUs new introductions,to adequatelymanage the Estuary'secosystem, resulting in restrictions on activities in and near the Estuary Table 7!. We discuss certain of these impacts below,

l. EXAMPLESOF POSITIVE ECONOMlC IMPACTS FROM INTRODUCT1ONSTO THE ESTUARY

a Food and t Resourc Skinner962! and Smith k Kato 979! review the history of the fisheriesin the Estuary. Although the introduced striped bass,American shad, white catfish, bullfrog, signal crayfish Pacifastacusleniusculus! and soft-shel!clam Mya arenaria! all supportedcommercial fisheries in the Estuaryin the past,only the crayfishis still commerciallyharvested today. These species and others,including many warrn- water gamefish introduced to the Delta, continue to provide sport fisheries. Stripedbass and shadsupported large commercial fisheries during the late 19th and first half of the 20th century.Striped bass were introducedin 1879and sold in SanFrancisco markets by 1889.The annual catch topped 500 tons by 1899,peaked at 1,000toms in 1903,and generally stayed over 500 tons until 1918.The commercial fisherythen declined and was closed in 1935to avoidcompetition with sportfishing Skinner, 1962;Smith & Kato, 1979!. Shadwere introduced in 1871,commercially harvested by 1874,and glutting the marketby 1880 Skinner,1962!. From 1900to 1945the Bay Area catchwas often over 500 tons, and peaked at over 2,800tons in 1917 Skinner, 1962;Herbold k Moyle, 1989!.The fish were mainly sold fresh until 1912,and thereaftersalted and export to China,with the saltedand canned;the sizeof the fishery was said.to be limited by demandrather than by the abundanceof shad.After 1945the catch averagedaround 300 tons until thefishery was eliminated in 1957by a banon gill- netting inside the GoldenGate Shebley,1917; Skinner, 1962; Smith & Kato, 1979!. Pagel91 Dtscllsslart

TaMe6. PositiveEconomic Impacts ofMarine, Estuarine andAquatic Organisms Introduced intothe San FranciscoEstuary

Detailsand refexences axeprovided inthe species descriptions inChapter 3.

ORG ANISMSStripedbass,CAUGHT American FOR FOOD,shad andFUR catfishOR SPORT supported conunercial fisheriesin the Estuary thatwere sometimessubstantial, untilcommercial fishingfor these species inthe Estuary wasbanned. Theabove species, plusblack bass, crapp ie,sunfish andcarp support recreational fisheriesin the CrayfishEstuary.aretaken from the Delta both corrunerciaUy andrecreationally. Thebullfrog Ranacatesbeiana hasbeen both raised inponds andharvested frompublic waters in CalThe ifoAsian rn i a.littleneck claxn Venerupis philippirraram andsometimes theAtlantic soft-shell clam Myaare~aria aretaken recreationally. Verrerupis isharvested commercially in thePacific northwestandsold in Bay Area markets as"Marula clams." A few other introduced molluscs are sometimesrecreationally harvested from theBay. TheAsian freshwater claxn CorÃcufa flurninea issometixnes taken recreationally from the Delta,Carbicula areharvested commercially from Lake Isabella in the southern end of the Delta's watershed. TheAsian freshwater snail Ciparrgapafudina wasimported and sold in Asianmarkets in thelate 19thcentury, andwas reportedly planted inthe Bay Area and the Central Valley 'to supply the xnarketsof SanFrancisco Bay." Watercressisan edible green which no doubt is sometixnesharvested recreationally. Muskratare trapped for theirfur,

BAIT~ Thegolden shiner and fathead minnow are corrunercially raisedas legally-designated freshwater in California. ~ Theyellowfin goby is commercially andrecreationally harvested foruse as bait, prixnarily for the introduced striped bass. Thefreshwater Asian clam Carbicuia is harvestedcoxnmercially and recreationally for bait. ~ Introducedcrayfish and bullfrog are caught recreationally foruse as freshwater bait. ~ Variousother introduced fish e,g. inland silverside! and invertebrates e.g, the mussel Myti?us galtopravincialis!are sometixnes used for bait.

B] OCONTROL ~ Themosquitofish Gambusia affinis contributes to the control of xnosquitoes.However, introductionsofother species forbiocontrol puxposes e.g. blue cat6sh tocontrol the introduced clamCarbicula, South American Keachetina weevils to control water hyacinth! appear to have hadno significant control effect, and have sometimes haxzned desirable species e-g. inland silverside Mertfdia beryllina!.

EROSION CONTROL ~ Accordmgtoone study, the Atlantic cordgrass Spartina altemiflora may be reducing erosion at SanBruno Slough. Discussion Page 192

Table 6. PositiveEconomic Impacts - continued

ENHANCEMENT OF ECONOMICALLY IMPORTANT FISH AND WILDLIFE TheSouth African brackish-marsh plant brass buttons provides food for waterfowland refuge; znarshesare sometixnes managed to encourageits growth. ~ The Atlantic cordgrassSpartina afternifloro might providemuch-needed cover for the endangeredCalifornia clapperrail. ~ Threadfinshad were introduced to provideforage for sport fish, although there is doubt about ' how usefulthey are asforage; to theextent that they do provideforage they xnayhave sixnply replacednative species; and someresearchers believe that they xnay in factcoznpete with young sportfish and reducethe populations of sportfish. ~ Many pelagicand benthic form part of thetrophic webs that support recreationallyand commercially important fish, but may have siznply replaced native invertebrates in this role.

White catfish were introduced in 1874. In 1875 the California Fish Commissionpredicted that they would support a commercialfishery by the followingyear, and in 1877reported that they constituted an "importantaddition to the fish food supplyof the city of Sacramento,"further described in 1879as "an immensesupply of food" Smith,1896!. By 1900catfish were being exported to Mississippi.The Bay Area's reported annual catch of catfishranged between 100 and 500tons from1905 to 1951 Skinner,1962!, but thefishery was closed in 1953due to decliningnumbers of fish Miller, 1966a;Borgeson 8z McCammon,1967!. Thesoft-shel! clam was first collected in theBay in 1874and by the1880s was the mostcommon clam in BayArea markets Stearns, 1881!, and public and private soft-shel!clam beds were established and managed throughout the Bay Bonnot, 1932!,The annual catch in theBay Area includingbays north to Bodega!was 500 to 900tons in 1889-1899,50-150 tons in 1917-1935,and then declined until the fishery closed in 1948,for reasonsthat are now unclearbut could involve a declinein the resourceor market competitionfrom other clams Skinner, 1962;Herbold et al., 1992!.Several workers have suggested that the soft-shell clams' early abundance in SanFrancisco Bay was due to replacementof populationsof the nativebent-nose clam Macorna rzasufa. It is unclear when signalcrayfish were introducedto California,but commercialharvest began in the Deltain 1970to supplythe Swedish market after the nativeSwedish crayfish was decimated by an introducedNorth American crayfish disease!.Initial landingsof 50 tons roseto over 250 tonsfrom 1975to the 1980s Osborne, 1977; Herbold & Moyle,1989!. The 1976 catch sold for a little over $300,000 Osborne, 1978!. Stripedbass has been the economicallymost important sport fishin the Estuary,accounting for a substantialtransfer of funds,variously estimated, from thosewho do thefishing to thosewho help them fish. Skinner 962, p. 172! reportedthat striped bass anglers were spending about $18 million peryear on the sport.McGinnis 984! reportedthat anglers took about 1 millionstriped bass in Page193 Disc'ussion

1980,spending about $7 million in the process. Herbold etal. 992! reported that the industriessurrounding striped bass fishing involving boats, marinas, and fishing equipmentandsupplies! were estimated toinject $45 million into local economies.

Severalsmall fish have been introduced to Californiain partto provide forageforlarger sport fish, including thethreadfin shad. However, there has been considerabledisagreement overthe value of the threadfin asforage ranging, accordingtodifferent authors, from "major" and "important" to"minor" and "inadequate"!,andits overall impact onsport fish involving competition with youngsport fish for food!, as reviewed in Chapter 3.

2, &~A'LES OFNEGATIVE ECONOMIC IMPACTS FROM INTRODUCTIONS TOTHE ESTUARY

MareIsland, in the upper part of San Francisco Bay, was chosen as the site for a navalbase partly in order to get upstream ofthe Bay's marine wood-boring organisms.However, theintroduction ofthe shipworm Teredo navalis, which toleratedmuch fresher water than did theBay's existing v,ood borers, led to the destructionof somefifty majorwharves, ferry slips and other structures in the northernpart of the Estuary between 1919 and 1921, including several atMare Island Figure 8!. Neily927! reported the damage toamount to$25 million, which, escalated to current992! dollars based on the EngineeringNews Record: General ConstructionCost Index; US CornrnerceDept., 1975, 1984, 1993! is $616million dollars.Although this figure does not includecollateral damage such as loaded freightcars that fell into the Bay when a railroaddock collapsed!, disrupted service andlost business, or thesubsequent costs of constructing,treating and maintaining structuresto be resistantto Teredo,nor doesit includedamage from Teredosince 1921or in otherparts of the Bay, it doesprovide some quantification ofthe scale of potentialeconomic impact from a singleintroduced organism. Otherintroduced wood-borers in the Bay are the shipwormLyrodus pedtcettatusandthe isopods Limnoria tripunctata and L, quadripunctata,and Chelriraterebrans. Although modern, chemically-treated pilings, marine timbers andmarine wood products are considerably more resistant to borerinfestations than untreatedwood, borer damage continues to occurto theBay's wooden pilings, docks and boat hulls. However,no current estimatesof this damageare available.

Hull foulingand othership fouling have a largebut generallylittle- recognizedeconomic impact. For example, Gordon 6 Mawatari992! report estimatesthat a coatingof slime1 mmthick on anotherwise clean hull canincrease skinfriction up to 80percent and reduce speed up to 15percent, an estimate Di sc ussi on Page]94

Figure8. SomeExamples ofDamage Caused by the Wood-boring Shipworm Teredo navalis in the San FranciscoEstuary

From Neily, 1927.

! Failureof dockat Oleum,Contra Costa County, Oct. 8. 1919,dumping several loadedfreight cars into San Francisco Bay. ! Collapseof theSouth VaHejo Ferry S ip,Solano County, Nov. 4, 1920, ! Collapseof theBenicia Municipal Wharfand House,Oct. 7, 1920. Dtscftsf l05 Page195 generallyborne out by towing tests WHOI, 1952!. Ross k Emerson974! calculated that"a luxuriant growth of barnacleson a one-square-footareaof a shipmay weigh asmuch as six pounds. On a largeship, the barnacles and other fouling organisms canadd as much as threehundred tonsto a ship'sweight...a heavily fouled ship mayneed as much as 50 percent more fuel to movethe same distance." In 1928it wasreported that U. S,shipping interests spent $100 million annually dealing with fouling WHOI, 1952, citing Visscher, 1928!. In the1940s, the British Adzruralty estimatedthat hull foulingon naval vessels increased fuel consumptionby 35'/ato 50'/oafter six monthsin temperatewaters or afterthree months in tropicalwaters WHOI, 1952!.More recently, Haderlie 984! reportedthat "all classes of [U. S.]naval shipsshow a tenpercent average yearly increase in fuelconsumption between dry dockings,and...most or all of thisis dueto increaseddrag caused by hull and propellerfouling," He furtherreported that in 1975the U. S.Navy spent $15 million a yearapplying antifouling coatings to its vessels,but that despitethis "the increased dragfrom hull foulingwas adding over $150 million to thenavy's annual fuel bill." Hull foulingcan thus result in a significantloss of maximumspeed and maneuverability,increased fuel consumption and decreased range, as well as necessitatingincreased maintenance and znore frequent drydockings issuesof concernto all vesselsbut especiallyto militaryvessels Haderlie, 1984!. WHOI 952! andHaderlie 984! reportedother impacts of shipfouling, including blocked fire mains; restricted or blocked flow to the main condensersserving the ship's engines, preventingthe developmentof full power;other fouled seawater pipe systems, sometimesrequiring the completedismantling of thesesystems; fouled propellers causingincreased vibration on board ship andloss of power;increased hull corrosion;fouled sonar domes causing degradation of performancedue to reduced sound transmission and reception,increased self-noise due to turbulence,and interference with mechanical operation;and increasedself-noise of the ship hull, a problem for military shipsseeking to evadedetection by enemysonar. Such considerationshave lead to the developmentand widespreaduse of anti-fouling compounds containingtributyltin TBT!, copper, mercury,arsenic and other materialswhich are toxic both to foulingand to nontargetmarine organisms, and to those working with thesecompounds. The cleaning and maintenance of TBT-coatedhulls has contributed to the creationof toxic "hotspots" in the Estuary. Though shipsmay be fouled by both native and non-nativeorganisms, virtually all of the commonfouling organismsin SanFrancisco Bay are introduced e. g. Graham & Gay, 1945;Banta, 1963; ANC & JTC,pers. obs,!. Thus fouling impacts for vesselsspending much of their time in SanFrancisco Bay are largely due to introduced species.

The fouling of Delta waterways by water hyacinth becameserious enough by the early1980s to block ferry boatsfrom reachingBacon Mand andprevent the island's produce reaching the market.In 1982 the CaliforniaI.egis!ature passeda bill ordering the control of water hyacinth in the Delta. Controlefforts included setting up barriersto keepmasses of hyacinth outof navigationchannels, spraying Discussion PageI96

Table7. NegativeEconomic Impacts of Introduced Marine, Estuarine and Aquatic Organisms

A. Examplesin theSan Francisco Estuary Detailsand references are provided in thespecies descriptions in Chapter 3,

WATERWAY FOUI.ING Water hyacinth ~ Navigationaland recreational impacts include blocking passage Eichharnia crassipes throughnavigable waterways and access to marinasand berths, European milfoil andfouling propellers and the water intakes of boat engines; Myriophyffum spicatum impactsha ve been serious enough to shut down rnarinas and bar Elodea Fgeriadensa ferry boatsfrom their routes. ~ Interferencewith salmonmigration. ~ Costsof herbicide applications including environmental and occupationalhealth impacts!, ~ Costs of biocontrol efforts. ~ Costsof mechanicalremoval and disposal.

FOULING OF VESSELSAND MARITIME STRUCTURES ~ Manykinds of plants and ~ Increasedfrictional resistance ofship and boat hulls, resulting in animals,including slowerspeeds, increased transit times, increased fuel costs, reduced seaweeds,sponges, maneuverability,andreduced effectiveness of military vessels. hydroids,tubeworrns, ~ Costof anti-fouhng coatings. mussels,barnacles, ~ Costsofpollution from the use of anti-fouling compounds bryozoansand sea squirts formulatedwith tributyltin, copper, mercury, creosote orother toxic materials. ~ Occupationalhealth costs of manufacturing, applying and maintainingcoatings of anti-foulingcompounds formulated from toxic materials. ~ Otherincreased maintenance costs, including the cost of timespent in drydock rather than in service,

WOOD BORING ~ Shipworrns Tereda ~ Damage to woodenmaritime structuresand vessels. navaiis and Lyrodus ~ Disruption of service, pedicel af us ~ Increased maintenance costs. ~ IsopodsLirnnaria spp. ~ Increased constructioncosts. and Chefura terebrans ~ Impactsfrom the use of toxicanti-fouling compounds, asnoted above,

BURROWING ~ Muskrat ~ Damageto levees,the wallsof ditches,stream banks and ~ Crayhsh Orconecfes and shorelines. Procambarus ~ Isopod Sphaerama ~ Chinese mitten crab

~ Isop od 6phaer o ma ~ Damageto styrofoamflotation of marinadocks, Pagel97 Discussion

Yab!e7. NegativeEconomic Impacts - continued

FOUUNG OF WATER SYSTEMS ~ Corbicufa,and to a + Increasedsedimentation in canals reducing flow rates. minordegree, Urnate/fa ~ Increasedmaintenance costs. and Cordyiophora

~ Water hyacinth ~ Fouledirrigation pumps and fish screens. PREDATIONON ANDCOMPETITION WITH ECONOMICALLY IMPORTANT SPKCIKS ~ Manyspecies offish ~ Reductionofpopulations ofcommercial and sport fish. ~ CrayfishOrconectes ~ Eluninationof theSacramento perch Archopfites interruptus, a virilis and Pacifastacus sport fish, from its native waters. leniuscufus ~ Reductionin populationsof certainnative fish, crayfish and frogs ~ BullfrogRana contributingtotheir listing or potential listing as threatened or catesb cia na endangeredspecies, resulting in: interferencewith waterdiversions, including restrictionson thelocation, timing and volume of diversionsand on the construction of new diversion facilities; interferencewith otherconstruction and development projects,both inside and outside the Estuary, ~ Costsof control efforts,such as rotenone applications. ~ Kills of nontargetsport fish from rotenoneapplications. ~ Occupationaland envirorunentaI health costs of rotenoneuse.

~ Atlan tie oyster dr ill ~ Predatorsor parasiteson oysters,clams and mussels. Urosalpinx cinereaand odostorniid snail Baonea bisuturalis

PROMOTION OF UNDESIRASLE SPECIES ~ Parrot's feather ~ Saidto provideexcellent mosquito habitat, Hyr>'ophytfurn aqua t ic urn

CROP DAMAGE ~ Crayfish Orconectes ~ Eatrice shoots,as apparently does the recentlyintroduced Chinese virilis and Procambarus mitten crab Eriocheir sinensis in China. cia rkii

INTERFERENCE WITH MONITORING Mussel Mytiius ~ Fifteenyears of estuarine water quality monitoring, based on ga1 ol pra vin cia1 is comparingcontaminant levels in the same species ofmussel in differentbays, may have been rendered questionable by the introductionof this secondand virtually indistinguishablespecies of musselwhich may take up and metaboIize contaminants at a different rate. Discussion Page 198

Table 7. NegativeEconomic Impacts - conhnued

ECOSYSTEM INSTABILITY/MANAGElVIENT UNCERTAINTY Continuoushigh rate of ~ Newspecies continually being introduced into the Estuary's biota introductions resultingin unmanageable fluctuations in populations of important species,inturn resulting in added restrictions onmany activities includingwater diversions, wastewater discharges, dredging, leveemaintenance, construction! inand near the Estuary.

Bt. Some Examples from Elsewhere

FOULING ~ Zebra mussel Dreissena ~ The Europeanzebra mussel was introducedto the GreatLakes m pofymorpha ballastwater in 1986and rapidly spread to 14states and 3 Canadianprovinces. It hasseriously fouled and in some cases caused the complete blockageofthe water intakes for municipal water systems, industrialprocess water systems, and cooling water systems forpower plants, lt hasincurred costs through the disruption ofservices; increased monitoring and maintenance requirements;changes in operations; theretrofitting of existingfacilities and added costsin the construction of new facilitiestomake them less vulnerable to musselfouling; the constructionof redundantfacilities to preventservice disruptions;the increaseduse of chlorine with attendant occupational,public and environmentalhealth costs!. It hasinterfered with commerce and recreation by fouling navigational buoys,maritime structures and vessels,with attendant costs, l t has fouled recreational beaches. In the pastyear, live zebramussels have been found attached to boatsand trailersentering California from the easternstates.

PREDATIONON ECONOMICALLYIlVIPORTANT SPECIES ~ Greencrab Carcinus ~ ThisEuropean crab was introduced to theeastern United States in maenas shipfouling and destroyed commercially valuable soft-shell clam Mya arenario!beds in New Englandand Mainein the I950s. Controlefforts included fencing, trapping and poisoning. Thegreen crab became established in San Francisco Bay in the late 1980s. Page199 L!iscussi on

Table7. NegativeEconomic Ixnpacts-continued

Chinese xnit ten crab ~ Introducedin ballastwater, thiscatadroxnous, burrowing crab Eriocheir si~ertsis becamephenomenally abundant in the rivers and upper estuaries ofGermany inthe 1930s, causing damage to trap and net fisheries andto river banks, leading to a government-sponsoredcontrol programthat, at its peak, trapped and destroyed tensof millions of crabsper year. Thexnitten crab becaxne established in SanFrancisco Bay in the 1990s,

Mnerniopsisleidyi ~ Discoveredto theBlack and Azov seas in theearly 1980s, this northwesternAtlantic ctenophore or 'combjelly' became phenoxnenallyabundant by1988, decixnating thezooplankton and virtuallydestroying the region's and fisheries,

DISEASE ~ 'red tide'-forming ~ Bloomsof dinoflagellatesthat produce sometimes-lethal dinoflagellatesand paralyticshellfish poisons PSP! have resulted from introductions other bloom-forcning ofthese plankton toAustralia and probably other parts of the plankton world.

Oriental lung fluke ~ In China,the xnitten crab Eriocheir sinejtsis is the second intermediatehost of thisdebilitating human parasite; human hostsare infected by eatingraw or inadequatelycooked, infected crabs.With themitten crabnow established in theBay Area, and snailsavailable that are capable of servingas first intermediate hosts,the lung fiuke could become established inCalifornia. ~ cholerapathogen Vibrio ~ In1991 during the South Axnerican cholera epidemic, ships' cholerae ballastwater from that continent arriving in U. S. ports in theGulf of Mexicofrequently carried the cholera pathogen, v'hich was also foundin fish andoysters in thoseports. herbicides,and releasing biocontrol agents, at a costthat reached $400,000/year L, Thomas,pers. comm., 1994!, though it onlypartly alleviated the problems.

d Wat stern Fauli TheAsian freshwater clam Corbicula flumt'nea plugged condenser tubes at thefederal water project's puxnping plant in the South Delta, colonized thebed of theproject's Delta-Mendota Canal trapping sedixnent andforming bars that reduced deliverycapacity, requiring the dewatering ofthe canal and the dredging ofover 50,000cubic yards of clam-bearing material!, and in southern California plugged undergroundpipes, turnout valves, and irrigation sprinklers Ingram, 1959; Hanna, 1966;Eng, 1979!. Discussion Page200

As discussedearlier in this chapterunder "Bi~roders," severalintroduced speciesburrow in and damageboth natural banksand man-madeembankments, includingmuskrat, two speciesof crayfishand the Chinesemitten crab in freshand brackishareas, and the isopod Sphaeromaquoyarrum in the more saline waters of theBay. In addition,we havefound the styrofoam blocks that provide flotation for marinadocks frequently riddled with Sphaeroma burrows, and though no quantitativedata are available,it seemsthat this must substantially shorten their life time.

red ion a d a in c n ial1 e i Severalintentional introductions may have had the"side effect" of reducing populationsof othereconomically important species. Economically important speciesin this contextinclude both species that are hunted or fished,and species that, becauseof theirdeclining populations, become listed or becomecandidates for listingunder the state or federal endangered species act orotherwise become species ofspecial concern!, triggering limitations oneconomic activities. Examples of such "sideeffects" suggested by various researchers include the following. In the 19thcentury, the destruction of water celery, a commonduck food, by introducedcarp might have reduced populations of canvasbackand other ducks Smith, 1896,citing Jordan & Gilbert,1894!. ~ Shebley917! reportedcarp to bethe principal cause of destructionof the Sacramentoperch, by eating its eggs and digging up its nests. Moyle pers. comm.!has suggested that predation by striped bass and black bass may have beenthe major cause of theelimination of Sacramentoperch from the Delta. McGinnis984! suggeststhat competition with introducedsunfish was the cause. ~ Severalworkers have suggested that threadfin shad compete with thefry of gamefish, including blackbass McConnell& Gerdes,1961; Von Geldern & Mitchil,197S!, crappie McConnell & Gerdes961! andstriped bass McGinnis, 1984!. ~ Inlandsilverside may compete with striped bass McGinnis, 1984! and prey on theeggs and fry of the endangered Delta smelt BDOC, 1994; Moyle, pers. comm.!. ~ TheShasta crayfish Pacifastacus fortis was proposed for listing,in largepart due to competitionfrom the introducedcrayfish Orconectes virilis and Pacifastacusleniusculus Anon., 1987!.

Prevention and Control C Substantialcosts have been incurred through efforts to eradicate populations of twopredaceous, nonindigenous fish presentin theDelta watershed white bass andnorthern pike beforethey reach the Deltawhere it is fearedthey wouM reduce populationsof endangeredspecies and sport fish. For both fish, eradication efforts havecentered around massive applications of the fish poison rotenone. The northernpike effort, for example,was preceded by threeyears of environmental Discussion Page202 reviewand litigation and a banon fishing in thearea resulting ineconomic losses tothe local economy!, followed by the application of12 semi-trailer loads of rotenoneby60 workers who were on site for over two weeks, with the cost of the on-sitework alone totaling over a milliondollars. The costs due to nontargetfish kills whichwere substantial!, other envirorunental health costs and occupational health costs are unknown. Theeffort failed to eradicatenorthern pike fromthe watershed.

h abili and e nt rtain Thegreatest impact from introductions tothe Estuary may be restrictions on theoperation ofthe California water system. In recent years a combinationof litigation,new legislation, and regulatory realignment has placed increasing environmentaldemands on thewater agencies that store and divert water from the Estuary'swatershed DWR, 1993!. Specifically, theagencies' ability to withdraw waterincreasingly depends on whether they can restore and sustain healthy populationsofanadromous andnative fish. This in turn will depend on the water agencies'and regulators' level of understanding ofthe ecosystem andtheir ability to figureout the necessary habitat conditions, including the amount and timing of instream flows needed, to maintain the fish. However,the achievementof an adequatelevel of understandingto reliably managethe Estuary is severelyhampered by a rateof introductionaveraging at least!one new species established in the Estuary every 24 weeks. For example, the arrival,growth and spread of the Asian clam Potamocorbula anrurensis in 19S6-87 appearsto have fundamentally altered trophic relations in the northern reach of the Estuary,and perhaps made models and calculations based on pre-1987 data obsolete andirrelevant Nichols,1985; Cohen, 1990; Alpine & Cloern,1992; Cohen & Carlton, 1995!.A constantlychanging species composition may make the ecosystem even less stable,and majorfunctional shifts more common. Under such conditions, the reliablemanagement of the Estuaryrequired of andpromised by! thewater agencies maybe impossible, Since water from the Estuary's watershed supports much of California'spopulation, industry and agriculture,the costsof failurecould be substantial.

3. SOiWKE!GV O'LES OF POTENTIAL IMPACTS

Someorganisms introduced to theEstuary might possibly be harvested and marketed.The European green crab Carcinus maerras, the Chinese mitten crab Eriocheirsinertsis, and the yellowfingoby are commercially harvested for food m partsof their nativerange Cohen et al.,1995!. The Asian sea squirt Styela clava is harvestedand eaten in Korea Abbott & Newberry,1980!. Water hyacinth leaves are soldas a vegetablein marketsin thePhilippines Ladines & Lontoc,1983!- Discuss iam Page202

~i~aIi~ Hallegraeffand his coworkershave demonstrated that toxic dinoflagellates thatproduce paralytic shellfish poisons PSP! were introduced to Australiafrom Japanin ballastwafer sediments Hallegraeff etal., 19S9; Hallegraeff & Bolch,1991.!. The introduction of toxic dinoflagellatesto the northeasternPacific could have costlyimpacts. In thePhilippines, three outbreaks in five yearsof a PSP-producing dinoflagellatepreviously unreported from the regioncost the localxnussel industry about $15million, poisonedover a thousandpeople and killed at leastthirty-four Corrales& Gomez,1989!. In SanFrancisco Bay clams and musselsare commonly collectedfor food in a poorly monitoredand largelyunregulated sport fishery Sutton,1981!. Although there is no commercialshellfishery in the Bay, dinoflagellatesthat arrive there in ballastwater could be readilycarried by coastal currentsor by coastaltransport of ballastwater to commercialshellfish beds to the north. In July, 1991during fhe SouthAxnerican cholera epidemic, the U. S. Food and Drug Administration discoveredthe causativeorganism of cholera,Vibrio cholerae, in oystersand fish from Mobile Bay,Alabama. Subsequently sampling of ballast water from nine ships arriving in Alabama and Mississippi from South America revealed Vibrio choleraein one third of them US Federal Register, 1991!.It has been suggestedthat cholera could have initially reached South America via ballast water Ditchfield, 1993!.

C! FUTURE INVASIONS

Many transport vectors releasingexotic speciesinto the San FranciscoEstuary rexnain active, and new invasions are certain to occur. Thesefall into eight categoriesdiscussed below, for eachof which we give examplesof potential invaders. In addition, at least 36 speciesof introduced aquatic plants, snails, fish, and one turtle are establishedin regionsadjacent to the greaterBay-Delta system Table 9!, some of which will undoubtedly spread into the Estuary.

1. ONGOING INOCULATIONS BY BALLAST WATER FROM OUI'SIDE THE NORTHEASTERN PACIFIC Shipsrelease in ballastwater scores if not hundredsof new specieson a monthly basisinto the SanFrancisco Estuary Table10!. Thatthis highly successful vector remains active in the Estuary is indicated both by the nuxnber of new invasionsnow occurring Table1! and by the continualappearance but uncertain establishmentof both small and largecrustaceans in the Bay Table8!. Around the world there havebeen a numberof important invasions,linked to ballastwater release, whose temperate climate biology suggest that thesespecies couldbecome established in the SanFrancisco Estuary. Ballast water from Japan could include the larvae of the carnivorous North Pacific SeaStar Asterias amurerisisand several species of Japanesedinoflagellates not yet establishedin San Page203 Discussion

Table8. RecentRecords ofNonindigenous Speciesin the San Francisco Estrxaxy whose Establishment is Uncertain

Native Date Species Range CollectedComments references!

INVERTEBRATES Moll usca:Gastropod a Pros obranchia Littorirra littorea ne Atlantic 1968-70, 14 collectedat Alamedak Bay Farm 1976-77, islandsin the northernSouth Bay in 1968- 1995 70,6 conectedat Selby on the east shore of SanPablo Bay in 1976-77 Carlton, 1969, 1979a!,ANC collectedone specimen on the San Franciscoshore in 1995,

ArthropodarCrustacea Isopoda Ianr'ropsisserricaudis Seaof Japan 1977 OaklandEstuary Carlton, 1979a!. 1VIunnasp. A 1993/94 J.Chapman. pers. comxn1995!. Splraerorrrasp. 1994 J.Chapman. pers. comm., 1995!, Amphipoda Anrpitlroe sp. 1993/94 J.Chapman. pers, comm., 1995!. Calli opiella sp. 1993/94 0. Chapman.pers. comm., 1995!. Drrlichia rnonocantlra 1990s M, Kellogg,pers. comm., 1995!. Lis1riella goleta 1990s M. Kellogg,pers. comxn., 1995!. Collected in LosAngeles Harbor in thelate 1980s, Syrrctrelidiumrniraculunr 1990s G. Gillingham,M. Kellogg,H. Peterson, pers.comxn., 1995!. Collected inLos Angeles Harbor in the late 1980s, Decapoda Exopaiaemorrcarinicauda Korea, China, 1993 Onespecimen L. Holthuis, pers. comm HongKong 1993!. Eropa!aerrronsp, 1995 Onespecimen, possibly E. carinicauda K. Hieb,pers, comm 1995!. unidentified Panrialid Onespecimen R. Van Syoc, pers. conun shrimp 1995!, VERTEB RATES Fish Anguilla arrguilla Atlantic, 1969 EuropeanEel,one specimen Skinner, 1971!. Europe Anguilla rostrata Atlantic, 1964, AmericanEel, one specimen caught in each eNkS 1994 of 1964k 1994.A fourthand unidentified America eel,dated 1987, estimated 1 m length,is preservedatthe Skinner Fish Facility in the Delta Skinner,1971; S. Walker,pers. comm., 1994!. Lrpisosterrs spatula seUSk 1991 AlligatorGar, one specixnen, 146cxn long Mississippi Raquel,1992!. basin Discussion Page204

FranciscoBay which, however, have become important invaders in southern Tasmania in a similar climatic regime Carlton et al., 1995!.Wafer from bays and estuariesof the Americanmid-Atlantic coastcould includethe Atlantic combjelly Mnemiopsisleidyi, which has becomea devastatingzooplankton and larval fish predator in the Blackand Azov Seaecosystems Shushkina k Musayeva,1990; Mutlu et al., 1994! and the Japanesecrab Hemigrapsussarrguineus, which was collected in 1988in New Jersey Mcoermott, 1991!and has now spread from North Carolina to G. Ruiz, pers. comm., 1995;JTC, pers. obs.!. The appearanceof several Atlantic coast invertebrates in the San FranciscoEstuary over the past 15 years discussedunder "Transport Mechanisms"in Chapter 5! suggeststhat the transport of additional organisms from the Atlantic is not unlikely. Ballast water from Europe could transport the freshwater-oligohaline gamrnarid arnphipod Corophium curvispinum, a major fouling organism Carlton et al., 1996!. Theseare clearly only a few out of scoresof examplesof known invaders that have become establishedelsewhere and which, should they hop on the ballast water conveyor belt, would be rapidly transported to the Estuary. In addition, we expect there are many organisms which have not invaded regions outside of their native range, but which could yet becomepotent invaders as was the casewith the Chinese clam, Potamocorbutaamurensis, which entered the Estuary in 1986!.

2. INTRACOASTAL TRANSPORT WITH SHIP TRAFFIC Coastalship traffic plays an unknownbut potentiallyimportant role in transporting invasions that have establishedelsewhere on the Pacific coast to the Estuary. Examplesinclude the transport of ballast water from the Columbia River potentially transporting the Asian copepodPseuctodiaptomus irtopirrus, now well establishedthere; Cordell et al., 1992!and from Pacific Northwest bays whichcould include whole floating plants of the Japaneseeelgrass Zostera japonica, which now occursfrom CoosBay to BritishColumbia!. The arrival of theAtlantic oligochaete I urnbricilluslineatus in the Bayis alsopredictable, and shouldbe specificallylooked for in enriched sediments. Coatesand Ellis 980! have noted its establishment in pulpmill effluentsites in northernVancouver Island, where it wasintroduced by international ship traffic. Ballastwater transport or shipfouling could play the central role in bringing to SanFrancisco Bay a numberof speciesof Asianand Atlantic seasquirts that have becomeestablished in the harborsof southernCalifornia since the 1980s G. Lambert,pers. comm., 1995!. Indeed, ship fouling from these harbors isprobably howthe Japanese seasquirt Ciona savignyi arrived in SanFrancisco Bay, having previouslybecome established in southern California. Coastal ship traffic from the southor thenorth may similarly have carried the Japanese seaweed Sargassum muticum as hull fouling into the Bay. Similarly,coastal ship traffic may transport introduced organisms now establishedin the San Francisco Estuary, including many known in the northeasternPacific only from the Estuary Appendix 4!, to other sites along the coast,The Estuary has likely operated in the past, and will likelycontinue to operate in the future,as the port of entryfor manyinvasions of thePacific coast. Page205 Discussion

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3.TO 7, QNGOINGINOCULATIONS BYOTHER MECHANISMS: FISHHUES PRODUCI'S, FISHERIESACI IVITIES,AQUARIA RELEASES In Table10 we list additional evidence for fiveadditional vectors for ongoing inoculationsinto the Estuary. These are ! thelive bait and lobster industries releasingnotonly the subject orgarusrns butthe living seaweed usedas packing materialand numerous associated invertebrates!; ! theherring-roe-on-kelp fishery transportingliveMacrocysfis kelpand associated invertebrates intothe Bay!; ! livebait releases ofbait fish; ! privateparty releases offish and shellfish; and ! releasesfrom horne or school aquaria. Each of these mechanisms isknown to have resultedin theat least temporary establishment of one or more non-native species inthe Estuary There are few regulatory mechanisms inplace to manage theextent or minimize the impact of thesevectors.

Table10. Examples ofOngoing Inoculations ofNonindigenous Speciesinto the San Francisco Estuary

MECHANISM:Species Inoculated

BALLAST WATER- Includesa wide variety of planktonic estuarine organistns frozn znany parts of the globe, Common types oforganisms include theadult or larvae ofcalanoid, cyclopoid andharpacticoid copepods, spionid, polynoidandother polychaete worms, diatoms, barnacles, bivalves, snails, flatwozms, decapods, chaetognaths,tintinnids, mysid shrimp, isopods, btyozoans, phoronid worms, aznphipods, dinoflagellates,hydtoids and other taxa CarltonIk Geller,1993!.

BAIT WORIvl SHIPMENTS: Includesa variety oforganistns from the Maine coast, including the baitworms Nereis virens and Glyceradibrauchiata; theseaweeds used fot packing them, especially AscophyIIum nodosum; and epiphyticseaweeds andsmall intertidal and epiphytic invertebrates found on the Ascophyllum. Recentexaminations ofsuch shiptnents arriving at bait shops in theBay Area found large nuznbers of livesnails, bivalves, aznphipods, isopods, hazpacticoid copepods, marine zzutes, insect larvae, polychaetes,oligochaetes, nematodes andforams Lau, 1995; ANC k JTC,pers. obs,!. This znechaniszn islikely responsible forthe recent establishtnent ofone Atlantic periwinkle in the Bay and the occasionalpresence ofanother, New bait worms now beginning tobe marketed inCalifornia, such as the Asianwortn Narnafycastis abiuma, tnay become established in the Estuary or carrywith thetn additional,yet unknown,organiszns,

HERRING-ROE-ON-KELP FISHERY: Includesthe kelp Macrocystis pyrifera collected from the Channel Islands in southernCalifornia and placedinSan Francisco Bayas a substrate forherring spawning Moore & Reilly,1989; Oda, 1989!, and organismsfound on Macrocystis. Although ithad been thought that M. pyrijera would rtot reproduce andbecome established m the Bay, it hasbeen found attached, and therefore reproducing, in the Bay L. Solarzano,pers. comm., 1994; ANC k JTC,pets. obs.!.

LIVE BAIT FISH: Includesprobable ongoing "bait bucket" releases ofthe red shinez Notropis Iutrrttsis into the fresh watersof theEstuary and its tributaries McGinnis, 1984; Jennings k. Saiki,1990! Page 208 Discussiort

Table10. Examples ofOngoing Inoculations - continued

PRIVATEPARTY RELEASES OFFISH OR SHELLFISH TO ESTABLISH FOOD OR SPORT InRESOURCES:recent years these types ofreleases probably account forthe white bass established mthe San JoaquinRiver drainage andnorthern pikeestablished inthe Feather River drainage, bothlikely to spreaddownstream tothe Delta; Chinese mitten crab established inSan Francisco Bayand tributary streamsandlikely tospread into the Delta and Central ValIey rivers; blue crab collected fromthe Delta,the Bay, and nearby coastal waters, but not established; andpossibly thealligator gar and Atlanticeels collected butnot established inthe Delta. Nonindigenous organisms currently imported aliveto Bay Area markets, and thus readily available forrelease into the Estuary along with any parasitesandepizoics theycarry, include green-lipped mussels fromNew Zealand, bluecrabs from ChesapeakeBayand American lobsters from Maine. The packing materials forthese shellfish, sometimesdiscarded into the Bay from dockside restaurants and distribution and repacking centers, maycontain yet additional organisms. Forexample, theseaweed Ascaphylfurn nodosuml used to pack Atlanticlobsters was found, on arrival in theBay Area, to containat least 29 other species of invertebratesand 7 otherspecies of seaweedfrom the Atlantic Miller, 1969!.

RELEASES FROM AQUARIA: Canintroduce and estabhsh a variety of orgarusms, which in thepast have likely included plants and theoligochaetes and entoprocts living on them!,snails, fish and turtles.

S. 1NTRACONTINENTALRECREATIONAL VESSEL TRAFFIC Recreationalvessels entering the SanFrancisco Bay and Deltafrom northern or easternstates have the potentialto transportwith them,on theirhulls or in incidentalwater aboard the vessel, a broadvariety of aquaticpest species, including aquaticweeds such as Hydrilfa!, snails such as the New Zealand snail Potatrtopyrgusartfipodarum, introduced to theMiddle River system of southernidaho, and sometimesoccurring in densitiesof 100sof 1,000sof snailsper squaremeter; Carlton et al.,1996!, and, especially, Eurasian zebra mussels Dreisserta polymorphaand Dreissenabugertsis!, which between 1993 and 1995have been interceptedat theCalifornia border on recreational boats coming from the Midwest and the Great Lakes.

Our certaintythat there will be additionalinvasions of the Estuarystands in contrastto our limited abilityto predictexactly which species or evenwhich trophic guilds!will invadeand when they will invade.Carlton 996b! discussessix scenarios,none mutually exclusive,that seekto explainwhy invasionsmay occur when they do; theseinclude changes in the donorregion, new donor regions, environmentalchanges in the recipientregion, changes in the dispersalvector, the phenomenon of invasionwindows, and stochasticinoculation events. All of these pertain to potential invasionsof the San FranciscoEstuary. A recentexample of a Discussion Page209 combinationof severalof theseprocesses apparently led to the successfulinvasion andsubsequent persistence of the Asian clam Potatnocorbula amurensis in the Bay as discussedin Chapter 3!. Predictingspecific guilds of invadersis oftenan elusive endeavor. However, wenote as an example the absence of certain truly -oligohaline taxafrom theEstuary where native marine and freshwater counterparts exist. Oglesby's 965! proposalthat the Atlantic worm Nereis succinea wassuccessful in the Bay because it inserteditself in this intermediatemicrohabitat that is, that it wasan "insertion invader" suggests that similar opportunities maybe available forother taxa. We notetwo such examples Table 4! among Bay isopods and arnphipods. Also to be expectedarefurther warmer-water species asnew colonists inthe Bay. The Bay has hada continuoushistory of suchsouthern species establishing on warmbay margins,including the barnacle Balanus , the tubeworm Ficopomatus and the bryozoan Zoobofryon, 1Remarkably,Cloern982! does not mention that any of these species areintroduced, andwhile OfficeretaL 982! note that +i~i~ and~ are introduced,they focus on the phenomenon of benthicfilter feeding inSan Francisco Bayas a "naturaleutrophication control" process. Page210

CHAPTER 7. CONCLUSIONS

Considerationof the biologicalinvasions of the SanFrancisco Bay and Delta ecosystemhas required examination of the recordsand statusof over 400species. Documentedplant and animal invasionsin the Estuarynow number 212species. An additional 123species are listed as cryptogenic not clearlynative or introduced a number that might represent less than half of the number of candidatecryptogenic taxa. An additional40 nonnativespecies were either reported previously or have been recently discovered but are not known to have become estabBshedin the Estuary, while another 36 nonnative speciesare established in adjacent aquatic ecosystems.

A! MAJOR FINDINGS

1. THE SAN FRANCISCOESTUARY CAN NOW BERECOGNIZED AS THE MOST INVADED AQUATIC ECOSYSTEM IN NORTH AMERICA. ~ Nonindigenousaquatic animals and plantshave had a profoundimpact on the ecology of this region, No shallow water habitat now remains uninvaded by exoticspecies and, in someregions, it is difficultto find anynative species in abundance.In someregions of the Bay,100'/o of thecommon species are introduced,creating "introduced communities." In locationsranging from freshwatersites in theDelta, through Suisun and San Pablo Bays and the shallowerparts of theCentral Bay to theSouth Bay, introduced species accountfor the majority of the speciesdiversity. 212introduced species are now recognized in the Estuary. Sixty-nine percent of theseare invertebrates, 4 percent protists, 15 percent are fish andother vertebrates,and 12percent are vascular plants. Marine introductions are dominatedby speciesfrom the Western North Atlantic 1 percent!,the WesternNorth Pacific3 percent!and the Eastern North Atlantic 5 percent!.Continental introductions are dominated by speciesfrom North America4 percent,mostly fish! and from Eurasia 9 percent,mostly plants!. ~ In additionto the212 introductions reported, 123 species are reported as cryptogenic not clearly native or introduced!, and the total number of cryptogenictaxa in theEstuary might well be twicethat. Thus simply reportingthe documented introductions and assuming that all otherspecies in a regionare native as virtuallyall previousstudies have done severely underestimatestheimpact of marineand aquatic invasions on a region's biota. Pagt211 Conclusions Despiteissues related todata quality that may frustrate efforts todetect refined temporalpatterns ofinvasions, thefirst collection records ofover 50 non- nativespecies inthe Estuary since 1970 appear toreflect a significantnew pulseof invasions,In the period since the beginning of introductions here takento be1850!, the Estuary has been invaded by anaverage of onenew speciesevery 36 weeks. Since 1970, the rate has been at least one new species every24 weeks,

2. A VASTAMOUNT OFENERGY NOW PASSES THROUGH AND IS UTILIZEDBY THE NONINDIGENOUSBIOTA OF THE ESTUARY. IN THE1990S, INTRODUCED SPECIES DOMINATE MANY OF THE ESTUARY'SFOOD WEBS. ~ Themajor bloom-creating, dominant phytoplankton species are cryptogenic. Becauseofthe poor state of taxonomic and biogeographic knowledge, it remainspossible that many of the Estuary's major primary producers that providethe phytoplankton-derived energyfor zooplankton andfilter feeders, are in fact introduced. ~ Introducedspecies are abundant and dominant among the zooplankton in thenorthern part of the Estuary, and throughout the benthic and fouling communitiesof San Francisco Bay. On theintertidal and sublittoral soft- bottomfloors of theBay these include 10 species of introducedbivalves, most of whichare abundantto extremelyabundant. Introduced filter-feeding polychaetesandcrustaceans mayoccur by the thousands persquare meter. On subtidal hard substrates,the musselMytilus galloprovincialtsis abundant, whilesublittoral substrates such as float foulingcommunities! support large populationsofintroduced filter feeders, including bryozoans, sponges and seasquirts.The holistic role of theentire nonindigenous filter-feeding guild includingclams, mussels, bryozoans, barnacles, seasquirts, spionid worms, serpulidworms, sponges, hydroids, and sea anemones in alteringand controllingthe trophicdynamics of the Bay-Delta system remains unknown Thepotential role of just one species, the Atlantic ribbed marsh mussel Arcuatutademissa, as a biogeochemicalagent in the economyof Bay salt marshes is striking. Introducedbenthic clams are capable of filteringthe entire volumeof the SouthBay and Suisun Bay once a day;indeed it nowappears that the primary mechanismcon.trolling phytoplankton biomass during summer and fall in SouthSan Francisco Bay is "grazing" filter feeding!by theintroduced clams Gemma,Venerupis, and Musculista. This remarkableprocess thus has a significantimpact on the standing phytoplankton stock in theSouth Say, and sincethese stocks are now being utilized almostentirely by introducedfilter feeders,passing the energythrough a non-nativebenthic fraction of thebiota mayhave fundamentally altered the energyavailable for native biota Conclusions Page 212

Droughtyear control of phytoplanktonbyintroduced clams resultmg m the failure of the summerdiatom bloom to appearin the northern reachof the Estuary is a remarkablephenomenon. The introducedsoft-shell clams Mya!alone were estimated tobe capable at timesof filteringall of the phytoplanktonfrom the water column on the order of onceper day. Phytoplanktonblooms occurred only during higher flow years,when the populationsof Mya and other introducedbenthic filter feedersretreated downstreamto saltierparts of theEstuary. However, phytoplankton populationsin thenorthern reach of theEstuary may now be continuously andpermanently and controlled by introduced clams. Arriving by ballast waterand first collected in theEstuary in 1986,by 1988the Asian clam Potarnocorbulareached and has since sustained average densities exceeding 2,000/m>.Since the appearance of Potamocorbula,the surrunerdiatom bloom hasdisappeared; presumably because of increasedfilter feeding by thisnew invasion.The Potamocorbvla population in thenorthern reach of theEstuary canfilter the entire water column over the channels more than once per day andover the shallowsalmost 13 timesper day, a rateof filtrationwhich exceedsthe phytoplankton's specific growth rate and approaches or exceeds thebacterioplankton's specific growth rate. Potarnocorbulafeeds at multiplelevels in thefood chain, consuming bacterioplankton,phytoplankton, and zooplankton copepods!, and so may substantiallyreduce copepod populations both by depletionof thecopepods' phytoplanktonfood source and by directpredation. In turn,under such conditions,the copepod-eating native opossum shrimp Neomysis may suffer a near-completecollapse in thenorthern reach. It wasduring one such patternthat rnysid-eating juvenile striped bass suffered their lowest recorded abundance.This example and the linkagesbetween introduced and native speciesmay provide a directand remarkable example of thepotential impact of an introducedspecies on theEstuary's food webs. Aswith the guild of filterfeeders, the overall picture of theimpact of introducedepibenthic and shallow-infaunal grazers and deposit feeders in the Estuaryis incompletely known. The Atlantic mudsnail Ilyanassa is likely playinga significant if not the mostimportant role in alteringthe diversity,abundance, size distribution, and recruitment of manyspecies on the intertidalmudflats of SanFrancisco Bay. The arrivaland establishmentof the greencrab Carcinus maenas in San FranciscoBay signals a newlevel of trophicchange and alteration The green crabis a foodand habitat generalist, capable of eatingan extraordinarily wide varietyof animalsand plants, and capable of inhabitingmarshes, rocky substrates,and foulingcommunities. European, South African, and recent Californianstudies indicate a broadand striking potential for thiscrab to significantlyalter the distribution, density, and abundance of prey species, and thus to profoundlyalter community structure in theBay. Page 213 Conclusions

~ Nearly30 species of introduced marine, brackish and freshwater fish are now importantcamivores throughout theBay and Delta. Carp, mosquitofish, catfish,green sunfish, biuegills, inland silverside, largemouth and smallrnouthbass, and striped bass are among the most significant predators, competitors,andhabitat disturbers throughout thebrackish and freshwater reachesof theDelta, with often concomitant impacts on nativefish communities.The introduced crayfish Procambarus andPacifastacus may playan important role, when dense, inregulating their prey plant and animal populations. ~ Nativewaterfowl inthe Estuary consume some introduced aquatic plants suchas brass buttons! and native shorebirds feedextensively onintroduced benthic invertebrates.

3. INTRODUCEDSPECIES MAY BE CAUSING PROFOUND STRUCTURAL CHANGES TO SOME OF THE ESTUARY'S HABITATS. ~ Spartinaalterniflora, which has converted 100s of acres of mudflatsin WillapaBay, Washington, intocordgrass islands, has become locally abundantin San Francisco Bay, and is competing with the native cordgrass Spartinaalterniflora has broad potential for ecosystem alteration, Itslarger andmore rigid stems, greater stem density, and higher root densities may decreasehabitat for nativewetland animalsand infauna. Densestands of S. alternifforamay cause changes insediment dynamics, decreases in benthic algalproduction because of lower light levels below the cordgrass canopy, and lossof shorebirdfeeding habitat through colonization of mudflats.

The Australian-New Zealand boring isopod Sphaerornaquoyanum creates characteristic"Sphaerorna topography" on manyBay shores, with many linear metersof fringing mudbanks riddled with its half-centimeterdiameter holes.This isopod may arguably play a major,if notthe chief,role in erosion of intertidal soft rockterraces along the shoreof SanPablo Bay, due to their boringactivity that weakens the rock and facilitates its removalby wave action. Sphaeromahas been burrowing into Bayshores for overa century, andit thusmay be thatin certainregions the land/water margin has retreated by a distanceof at leastseveral meters due to thisisopod's boring activities.

4. WHILE NO INTRODUCTIONIN THE ESTUARYHAS UNAMBIGUOUSLYCAUSED THE EXTINCTION QF A NATIVE SPECIES,INTRODUCTIONS HAVE LED TO THE COMPLETE HABITAT OR REGIONAL EXTIRPATION OF SPECIES,HAVE CONTRIBUTED TO THE GLOBAL EXTIN CTION OF A CAUFORNIA FRESHWATERFISH, AND ARE NOW STRONGLYCONTRIBUTING TO THE FURTHERDENIISE OF ENDANGERED MARSH BIRDS AND IVL-'&%MALS, Introduced freshwater and anadromousfish have been directly implicatedin the regionalreduction and extinction, and the global extinction, of four Conclusions Page 214

native California fish. The bluegill, greensunfish, largemouth bass, striped bass,and black bass,through predationand through competitionfor food and breedingsites, have all beenassociated with the regionalelimination of the native Sacramentoperch from the Delta. The introduced inland silverside may be a significant predator on the larvae and eggs of the native Delta smelt. Expansionof the introducedsmallmouth bass has beenassociated with the decline in the native hardhead. Predation by largernouth bass,black bass and striped bassmay have been a major factor in the global extinction of the thicktail chub in California.

The situation of the California clapper rail may serve as a model to assess how an endangeredspecies may be affectedby biological invasions.The rail suffers predation by introduced Norway rats and red fox; it may both feed on and be killed by introducedmussels; and it may find refugein introduced cordgrass,although this samecordgrass may compete with native cordgrass, perhaps preferred by the rail. Other potential model study systemsinclude introducedcrayfish and their displacementof native crayfish;introduced gobies and their relationship to the tidewater goby; and the combined role that introduced green sunfish, bluegill, largemouth bass, and American bullfrog may have played in the dramatic decline of native red-legged and yellow-legged frogs.

5. THOUGH THE ECONOMIC IMPACTS OF INTRODUCED ORGANISMS IN THE SAN FRANCISCOESTUARY ARK SUBSTANTIAL, THEY ARK POORLY QUANTIFIED. Though someof the fish intentionallyintroduced into the Estuaryby government agenciessupported substantial commercial food fisheries, these fisheriesall declinedafter a timeand arenow closed.The signal crayfishfrom Oregon,whose means of introductionis unclear,supports the Estuary'sonly remaining commercial food fishery based on an introduced species.

~ The striped bass sport fishery has resulted in a substantialtransfer of funds from anglersto thosewho supply anglers'needs, variously estimated, between1962 and 1992,between $7 million and $45million per year. However, striped bass populations and the striped basssport fishery have declined dramatically in recent years.

~ Governmentintroductions of organismsfor sport fishing, as foragefish and for biocontrol have frequently not produced the intended benefits, and have sometimeshad harmful "sideeffects," such as reducingthe populationsof economically important species.

~ Few nonindigenousorganisms that were introducedto the Estuaryby other than governmentintent have producedeconomic benefits. The clamsMya and Venerupis,accidentally introduced with Atlanticoysters, have supported commercialharvesting in the Bay or elsewhereon the Pacificcoast, and a smallamount o recreationalf harvesting inthe Bay though these clams may have,to some extent, replaced edible native clams!; theAsian clam Carbicula iscommercially harvestedfor foa and bait in Cahfo~a ona smallscale; the Asianyellowfm gobyis commercially harvestedfor bait; muskrat aretrapped forfurs; and the South African marsh plant brass buttons provides food for waterfowl,There dp not appear tobe any other significant economic benefits thatderive from nongovernmental oraccidental introductions tothe Estuary. gleintroduced organism, theshipworm Teredo riavalis, caused $615 million in l992 dollars! ofstructural damage tomaritime facilities in3 years Theeconomic impacts ofhull fouling and other ship fouling are clearly very large,but are not documented orquantified forthe Estuary. Most of the foulingincurred in the Estuary isdue to nonindigenous species. Indirect impactsdueto the use of toxic anti-fouling coatings mayalso be substantial. Waterwayfouling by introduced water hyacinth hasbecome a problem inthe Deltaover the last fifteen years, with other introduced plants beginning to addto the problem inrecent years. Hyacinth fouling has had significant economicimpacts, including interference with navigation. ~ Perhapsthe greatest economic impacts may derive from the destabilizing of theEstuary's biota due to the introduction andestablishznent ofan average of onenew species every 24 weeks. This phenomenal rate of species additions has contributedto the failure of water usersand regulatoryagencies to managethe Estuary soas to sustain healthy populations of anadromous and native fish,resulting in increasinglimitations and threatsof limitations on water diversions,wastewater discharges,channel dredging, levee maintenance,construction and other economicactivities in and near the Estuary, with implicationsfor the v hole of Califorrua'seconomy.

B! RESEARCHNEEDS

Much remains unMown in terms of the phenomena,patterns, and processes of invasionsin theBay and Delta,and thuslarge gaps remain in the k owledge neededto establisheffective management plans. The followingare a l f importantresearch needs and directions- l. EXPEi~tIvKhJTAL ECOLOGY OF INv~g!oNS As discussedin Chapter3, only a fewof thehundreds of ' v d Est a y " jectof quantitativeexperimental studies elucid to th roles ry o ys em and their impactson nativebiota. Such studies should receivethe»ghest priority, Conctusioes Page216

2. REGIONAL SHIPPING STUDY Urgentlyrequired is a SanFrancisco Bay Shipping Study which both updates the 1991data baseavailable and expandsthat data baseto all Bay and Delta ports. A biologicaland ecologicalstudy of the natureof ballastwater biota arriving in the Bay/Delta systemis urgently required. Equally pressmg is a study of the fouling organismsentering the Estuaryon ships'hulls and in ships'seachests, in order to assesswhether this mechanism is now becoming of increasing importance and in order to more adequately define the unique role of ballas'twater. A Regional Shipping Study would provide critical data for managementplans.

3. INTIVOHGIONAL HUMAN-MEDIATED DISPERSAL VECI'ORS Studies are required on the mechanismsand the temporal and spatial scales of the distribution of introduced speciesby human vectors after they have become established.Such studies will be of particular value in light of any future introductions of nuisance aquatic pests.

4. STUDY OF THE BAITWORM AND LOBSTER SHIPPING INDUSTRIES Our work has identified a major,unregulated vector for exotic species invasions in the Bay; the constant releaseof invertebrate-ladenseaweeds from New England in associationwith bait worm and lobster! importation. In addition a new trade in exoticbait has commenced,centered around the importation of living Vietnamese nereid worms, and both the worms and their substrate deserve detailed study, Thesestudies are urgently neededto addressthe attendantprecautionary management issues at hand.

5. MOLECULAR GKNET1C STUD?ES OF INVADERS The applicationof modern moleculargenetic techniques has alreadyrevealed the cryptic presenceof previously unrecognizedinvaders in the Bay: the Atlantic clam Macomapefalum, the Mediterraneanmussel Mytilus galioprovincialis,and the Japanesejellyfish Aurelia "aurita."Molecular genetic studies of the Bay'snew greencrab Carcirjus!population may be of critical value in resolvingthe crab's geographicorigins and thus the mechanismthat brought it to California.Molecular geneticstudies of wormsof the genusGlycera and Nereis in theBay may clarify if New Englandpopulations have or arebecoming established in the regionas a result of ongoinginoculations via thebait wormindustry. Molecular analysis of other invasionswill doubtlessreveal, as with Macomaand Mytilus, a numberof heretofore unrecognized species. Conclusions Ppgc217

6. INCREASEDUTlLIZATION OF EXOTIC SPKCIKS Fishery,bait, and other utilization studies should be conductedon developing or enlargingthe scope of fisheriesfor introducedbivalves such as Mya, Venerupis, andCorbicula!, edible aquatic plants, smaller edible fish suchas Acanthogobius!, and crabs Carcinusand Eriocheir!.

7. POTENTIAL ZEBRA MUSSEL INVASION Studiesare needed on thepotential distribution, abundance and impacts of zebramussels Dreissena polymorpha and/or D. bugertsis!in California,to support effortsto controltheir introductionand to designfacilities suchas water intakes and fish screens!that will continueto functionadequately should the rnussels become established.

S. ECONOMICIMPACTS OF WOOD BORERSAND FOUUNGORGAN1SMS Theeconomic impacts of wood-boringorganisms shipworms and gribbles! andof foulingorganisms on commercialvessels, on recreationalcraft, in portsand marinas,and in waterconduits! are clearlyvery largein the SanFrancisco Estuary, but remainlargely undocumented and entirely unquantified. A moderneconomic studyof thisphenomenon, including the economic costs and ecological impacts of controlmeasures now in placeor forecast,is critically needed.

9. ECONOMIC,ECOLOGICAL AND GEOLOGICAL IMPACTS OF BIOERODING NONIYDIGENOUS SPKCIES Largelyqualitative'data suggest that the economic, ecological, and geological impactsof theguild of burrowingorganisms that havebeen historically and newly introducedhave been or areforecast to potentiallybe extensivein the Estuary. Experimental,quantitative studies on theimpacts of burrowingand bioeroding crustaceansand muskratsin the Estuaryare clearlynow neededto assessthe extent of changesthat have occurred or arenow occurring, and to formthe basis for predictingfuture alterationsin the absenceof controlmeasures,

10- I'OST-INvASION CONTRoL MECHAN! SMS Whileprimary attention must be paid to preventingfuture invasions, studies shouldbegin on examiningthe broad suite of potentialpost-invasion control mechanisms,including biocontrol, physical contairunent, eradication, and related strategies.A RegionalControl Mechanisms Workshop for pastand anticipated invasions could set the foundation for future research directions. Page 218

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APPENDIX 1 A!. INTRODUCED TERRESTRIAL PLANTS, BIRDS AND MAMMALS REPORTED FROM THE SAN FRANCISCO ESTUARY.

Native Range; N - North n - northern e - eastern S - South s - southern w - western

Listed in: Dl MadroneAssoc. 980!. reportedin the Sacramento-SanJoaquin Delta D2 Herboldk Moyle 989!, AppendixA: VascularPlants of the Sacramento-San JoaquinDelta IM Atwater et al, 979!, Table 3: Common Introductions in Tidal Marshes of the SanFrancisco Bay Area GL Mills et al. 993!, nonindigenous aquatic plants and algae of the Great Lakes HR Mills et al, 995!, nonindigenousorganisms in the HudsonRiver

Species Cornrnon Name Native Range Listed in:

PLANTS Vascular Plants QJI l~lglgii Apium graveo!ens celery Eurasia TM A triplex semibaccata Australian salt bush Australia D2, TM Carpobrotus edulis iceplant s Africa D2 Chenopodiurrtalbum lambs'quar ters Europe TM Cirsium v ulgare bull thistle Europe D1,D2, TM Coni'um maculatum poisonhemlock Europe Dl, D2, TM GL! Cotula australt's Au st r al ia TM Di psacusfullonum wild teasel Europe TM Foeniculumvulgare fennel s Europe D1, D2, TM Metitotus alba white sweetclover Eurasia D1, D2, TM Men tha arvensis Europe?e N America? Mentha x pi perita peppermint Europe TM GL, HR! Phyla nodrflora mat-grass S America Dl, D2, TM Plantago major common plantain Europe ftumex crispus curly dock Eurasia Dl, D2, TM HR! Solanurn dulcamara bittersweet n Eurasia TM GL, HR! Solarium>nigrum or americanum nightshade Eurasia or S America D2. TM HR! Tamartx sp, tamarisk Europe,Asia or Africa D2 Tetragonia tet ragonioides New Zealand spinach New Zealand, Australia Veroni ca anagailis-aquatica water speedwell Europe D2

A rundo donar giantreed Europe Dl, D2 Bromus diandrus ripgutgrass Eurasia D1,D2,TM Bromus hordeaceus soft chess Eurasia TM Cortaderia selloarta patnpas grass e S America D1,D2, TM F chinocioa cr us-galli barnyardgrass Eurasta and Afnca Dl GL, HR! Fest uca pro tensis meadow fescue Europe Hordeum rnurinurn hare barley Europe Polypogon rr>onspeliensis rabbit's-foot grass stw Europe D1,D2, TM A ppendix 1 A!

Species NativeRange

VERTEBRATES Birds Col u mba livia pigeon,rock dove Eurasia Passer domesticus housesparrow Eurasia Phasianus colchicus ring-neckedpheasant Asia Sfurnusvulgaris starling Eurasia Mammals Felis felis cat Eurasia Mus musculus Eurasia Ratfus vorvegicus Norway rat Eurasia Vulpes vulpes red fox e gc midw NAxnerica APPENDIX1 B!. DESCRIPTIONSOF INTRODUCEDTERRESTRIAL PLANTSREPORTED FROM THE SAN FRANCISCO ESTUARY

ApiumgraveoIens Linnaeus [APIACEAE]

CELERY Celeryisa nativeofEurasia, widely cultivated andcommonly naturalized in wetplaces atlow elevations inCalifornia ]epson, 1951; Munz 1959; Hickrnan, 1993!. It islisted by Atwater etal. 979! as common intidal marshes ofthe San Francisco Estuary.

Atriptexsemibaccata R.Br CHENOPODIACEAE]

AUSTRALIAN SALTBUSH Australiansaltbush, drought-resistant andadapted to alkaline soils, was introducedtothe United States as a forageplant according toRobbins etal. 941!, althoughSpicher & Josselyn 985!say that it wasintroduced inships' ballast. It is commonlyfound in waste places, shrubland andwoodland throughout mostof California except for parts of the Cascade Range and Sierra Nevada!, toUtah, Texas andnorthern Mexico Hickman, 1993!. Atwater et al.979! list it ascommon in tidal marshesinall parts of the San Francisco Estuary, and it isreported asoccasional in theDelta Madrone Assoc., 1980; Herbold & Moyle,1989!. We' ve observed it just aboveand occasionally below the highest tidernarks in San Francisco Bay saltmarshes,on dikes and on riprappedbanks.

Carpobrotrisedulis Linnaeus! N, E. Br.[AIZOACEAE]

SYNONYMS:Mesc m bryanthem am edu te

ICEPLANT, SEA FIG Nativeto South Africa, iceplant was introduced into the United States inthe early1900s forerosion control along railroad tracks and has been extensively planted alonghighways, onsand dunes and in high fire-nsk areas. Itsfruits have been widelydispersed from planted areas by several native mammals, andit isnow commonand naturalized along much of the California and Mexican coasts, where it maycompete with native species, including several threatened orendangered plants Jepson, 1951;Munz, 1959; O'Antonio, 1993;Hickman, 1993; Albert, 1995!. We Appendix 1 8! Page Al-4 haveoften seen it at the marginsof saltmarshes, with someplants occasionally below the level of the highest tides.

Chenopodiumalbum Linnaeus, 1753 [CHENOPODIACEAE]

LAMB'S QVARTERS, PIGWEED

A native of Europe, lamb's quarters is a common.weed in waste and fallow places and along roadsides,widely distributed over North Axnerica and other temperate regions of the world Munz, 1959;Hickman, 1993!,and reported in California by Robbins et al. 941! as an important host plant of the beet leafhopper. In Suisun Marsh it was found at 8 of 48 sites in a 1989survey. In 1987,pickleweed, saltgrass and lamb's quarters comprised the principal vegetation at one site in the marsh Herrgesell, 1990!.Atwater et al. 979! listed it as a comxnonintroduction in the tidal marshesof the San FranciscoEstuary. Cirsium vutgare Savi! Ten. [ASTERACEAE]

BULL THISTLE, COMMON THISTLE

Bull thistle is native to Europe, and is an aggressiveweed in North America commonin wasteplaces Munz, 1959;Hickman, 1993!. It is listed by Atwater et al. 979! as coxnmonin tidal marshesof the SanFrancisco Estuary, and is reported as comxnon in the Delta Madrone Assoc.,1980; Herbold & Moyle, 1989!.

Conium maculatum Linnaeus [APIACEAE]

POISON HEMLOCK

Poison hexnlock is a native of Europe and was established in North America by 1818 Nuttall, 1818!.It is commonin moist,disturbed ground at low elevationsin California Oepson,1951; Munz 1959;Hickman, 1993!. It is listedby Atwater et al. 979! as commonin tidal marshesof theSan Francisco Estuary, and is reportedas occasionalin the Delta MadroneAssoc., 1980; Herbold & Moyle, 1989!.

Cotuta australis Sieber! Hook. f. [ASTERACEAE] ThisAustralian plant was initially reportedin Californiaas occurring"along the streetsof manyof our townsand cities" including Berkeley, Oakland and San Francisco Robbins et al.,1941; jepson, 1951!. Munz 959! describesit as a "very coxnmonand troublesome weed about gardens, city lots,etc." Hickman 993! reports it as a common weed at low elevations "in urban coastal areas."Atwater et al, 979! list it ascomxnon in tidalmarshes of theSan Francisco Estuary. Appendix 1 8! Page Al-5

Dipsacusfullonum Linnaeus[DlPSACACEAE]

WILD TEASEL, FULLER'S TEASEL A nativeof Europe,wild teaselis commonlyfound at roadsidesand in pastures,old fieldsand other waste places, and occasionally at moistsites, more-or- lessthroughout cisrnontane California including the SanFrancisco Bay Area Oepson,1951; Munz, 1959; Hickrnan, 1993!. Atwater et al. 979! list it ascommon in tidal marshes of the San Francisco Estuary.

Foeniculumvulgare Miller [APIACEAE]

FENNEL, SWEET FENNEL Fennelis nativeto southernEurope and widely escapedfrom cultivation in thewestern hemisphere. It is commonlyfound on roadsidesand in wasteplaces at low elevations Jepson, 1951; Munz 1959; Hickman, 1993!. It is listedby Atwateret al, !979! ascommon in tidal rnarshesof the SanFrancisco Estuary, and is reportedas common in the Delta Madrone Assoc., 1980;Herbold 8xMoyle, 1989!.

Melilotus alba Medikus [FABACEAE]

WHITE SWEETCLOVER

SYNONYMS: Meli lot us alb>

Mentha arvensis Linnaeus [LAMlACEAE] Munz 959! reportedthis plant asoccurring in Californiain "severalforms that arequestionable as to whethernative here," Hickman 993! states"some plants sterile;some plants naturalized from Europe,"while Mills et al. 995! describeit as a nativeNorth Americanmint. Jepson951! called Menthaarvensis the "tule- mint," common in marshes and meadows, and Hickrnan 993! reports it from moist areas,stream banks and lake shoresthrough much of California. Atwater 980! reportedit from the bank of an islet at SandMound Sloughin the Delta. Appendix l B! Page Al-6

Mrntha x piperitaLinnaeus [LAMIACEAE]

PEPPERMINT

SYNONYMS:Mcrttha piprrita Mcntha citrata

Hickman993! describes this plant as a generallysterile hybrid of M. aquatrca andM. spicata,which propagates asexually via undergroundshoots Mills et al,, 1993!.A nativeof Europe, peppermint was reported inNew York by 1843 Torrey, 1843!.It iswidely cultivated for its oil and is commonly escaped in Canada, the easternUnited States, and California, where it is foundin fieldsand wet places Qepson,1951; Mason, 1957; Munz, 1959; Hickman, 1993!. It is listedby Atwater et al, 979!as common in tidalmarshes of theSan Francisco Estuary.

Phylanodiflora Linnaeus! Greene var. rtodijlora [VERBENACEAE]

MAT-GRASS, GARDEN LIPPIA

SYNONYMs:Phy1a ~todif/ora var. reptans Lippia nodifloravar. rosea Lr'ppianodiPora var. canescrrts Lippia nodiflora var. reptarts Lippia filiforrrtis ZappnttianOdijlOra Var. reptarIS NaturalizedfromSouth America, mat-grass hasbeen planted asgroundcover andto resist erosion onlevees, Itis well established inlow elevation wetplaces, ditchesandfieMs inmany parts ofCalifornia including theCentral Valley and the Ba>Area Jepson, 1951; Mason, 1957; Munz, 1959; Hickrnan, 1993!. Inthe Delta it has beenvariously listed asespecially common inthe region Robbins eta],, 1941!, commonintidal marshes Atwater etal,, 1979!, and uncommon Madrone Assoc., 1980;Herbold h Moyle,1989!,

Plaritagonraj or Linnaeus[PLANTAGINACEAE! COMMONPLANTAIN, WHITE MAN'SFOOT NaturalizedfromEurope, common plantain isa weed ofdamp waste places Jepson,1951;Munz, 1959; Hickman, 1993!. Atwater etal, 979! list it as common in tidalmarshes ofthe San Francisco Estuary. Pag

Sofarrrrmdufcamara l.innaeus [SOLANACEAE]

BITTERSWEET,CLIMBING NIGHTSHADE Thismember of the nightshadegenus is nativeto northernEurasia and was importedtoNorth America from Europe asa remedyfor rheumatism andscurvy Torrey,1843!. It escaped and become established by]8]8 Nuttall,18]8! and is now foundthrough much of theUnited States and Canada. In California it grows in moistplaces and marshes at lowelevations along the central coast and in theBay Area Munz, 1959; H ickrnan,]993!. It is listedby Atwateret al. 979!as common in tidal marshes of the San Francisco Estuary,

5 ofrrrrrr m nrrr ericarr rrm of Sala rr um rrigrumMiller [SOLANACEAE!

SMALL-FLOWERED NIGHTSHADE or BLACK NIGHTSHADE

SYNONYMS: see below Theplant listed by Herbold& Moyle ]989! asSolrrrrrrm rrodrflorrrrrr, present in theDelta, and by Atwater et al. 979! asSolarrum rrodrfolirrm possibly a typographicerror!, common in tidalmarshes of theSan Francisco Estuary, might referto eitheror both of S. amer!'carrrrmor S. rrigrrrm.Munz 959! lists S. rrrgrrrmof authorsas a synonymof S. rrodifolirrm.Hickman 993! lists S. rrigrrrmas a native of Eurasia,found in low elevation disturbed sites and damp fields in cismontane California,including the BayArea, and "expected elsewhere." It was reported from NewYork by 1843 Torrey, ]843!, where it mayhave either escaped from cultivation or beentransported in solid ballast, as it was found on ballast dumping grounds in Ne~ York City Brown, ]88O!.]t is now reportedas commonin the easternUnited Statesand from California to Washington. Appendix 7 B! PageA3-S

Although treating S, americanismas a native, Hickman 993! states that it mightbe anearly introduction from South America, listing S. nodiflorumJacq. as a synonym.

Tamarixspp. [TAMARICACEAE]

TAMARISK, SALT CEDAR

Jepson951! listsone species of tamariskin California,Mason 957! lists three,Munz 959! listsfour, Munz 968! listsseven, and Hickman 993! lists five. All of theseare native to Europe,Asia or Africa.Jepson 951! reportedFrench tamarisk,Tamarix gatlica, from White Sulphur Creek in theNapa Valley; Mason 957! andMunz 959! reportedAfrican athel, Tarnarix aphyBa, planted and occasionallyescaped in theSacramento and San Joaquin valleys; and Herbold & Moyle989! reportedTamarix sp. from the Delta. Dudley & Collins995! describe aninfestation of tamariskcovering several thousand acres of riparianand upland areasnear the Kern National Wildlife Refuge in theCentral Valley, and note T. chilensis,T.ramosissima, T galtica and T. parviflora asintroduced species posing a serious,documented threat to sensitivespecies or ecosystemsin California.

Tetragoniatetragonioides Pallas! Kuntze [AIZOACEAE] SYNONYMS: Tet rago nia expan saMurray

NEW ZEALAND SPINACH

Kozloff983! reportedthis plant as well establishedin Californiaand southernOregon, "found atthe edges ofsalt marshes andbay shores, but decidedly abovethe high-tide mark." We have found it atand above the high-tide line in San FranciscoBay, often growing in amongriprap, and rarely on bare soil below the high-tideline. Hickman 993! reportsit commonon sand dunes, bluffs and the marginsof coastalwetlands throughout coastal California. It's native range includes NewZealand, Australia and possibly other locations inSoutheast Asia. It reportedly canbe cooked& eatenlike spinach.

Veronicaanagaltis-aquatica Linnaeus [SCROPHULARIACEAE]

WATER SPEEDWELL

A nativeof Europeand widely naturalized in Northand South America, waterspeedwell is occasionallyfound in wetmeadows, on stream banks or in slow streamsinCalif'ornia Munz, 1959; Hickman, 1993!. HerboM & Moyle 989! report it Appendix III Page AI-9 fromthe Delta. Sterile hybrids with chain speedwelI, Veronica catenata, havebeen foundin somemixed pppulatipns Hickman 1993!.

Arundodonax Linnaeus [POACKAE]

GIANT REEI3,CARRIZO

Giantreed is nativeto Europe it is the ree mage! and is foundat moistsites, such as ditches, streams «P ~ in cismontaneand desertCalifornia Munz, 1959' »c~ reportedit "escapedalong irrigation ditches" in reportedas occasional on herbaceous banks in the Delta MadroneAssoc' 80; erbold& ~pyle,1989!, and Atwater 980! recordedit from thebank of anis e SandMound Slough in the pelta.Although it has been planted alongriv for erosioncontrol, it is an invasiveweed in some riparian areasin California and the NatureConservancy has organized a pilotproject to controlit with herbicidesin RiversideCounty Sullivan, 1994!.

Bromus diandrus Rpth POACEAE]

SYNONYMS:Bromris rigidus Roth. Bromus diandrusvar. gussonei

RIPGUT GRASS

Ripgutgrass is nativeto Eurasia.It is widely distributed in open,generally disturbed places and fields in California,and is also known from BritishColumbia andSouth America Hickman, 1993!. Atv ateret al. 979! listGussone's ripgut grass as common in the landward fringesof tidal rnarshes around San Pablo and Suisun bays,and Madrone Assoc. 980! andHerbold & Moyle 989! reportit asfrpm the Delta

Bromus hordeaceusLinnaeus [POACEAE]

SYNONYMS: Bromus moIlis Linnaeus

SOFT CHESS Softchess is nativeto Eurasia,and widely distributed in thewestern hemispherein open, of en disturbed places Hickman, >993!. It is listedby Atwater et al. 979! ascommon m the landward fringes of tidal marshesaround San Pablo and Suisun bays- Appendix I B! Page AI-Io

Cortaderia selloana Schultes! Asch. k Graebner [POACEAE]

PAMPAS GRASS

Pampas grass is a nahve of eastern South America, escaped from cultivation in coastalCalifornia and the southernU. S. and commonin disturbedplaces at low elevation, including the Bay Area Munz, 1959;Hickman, 1993!.Atwater et al. 979! list it as commonin tidal marshes,mainly in the Delta, and othersreport it as commonin the Delta MadroneAssoc., 1980; Herbold k Moyle, 1989!.Me somewhatsimilar C.jubata,also reportedfrom the Bay Area,is highly invasive.

Echinocloacrusgalli Linnaeus! Beauv. [POACEAE]

BARNYARD GRASS, WATER GRASS

Native to Eurasiaand Africa, this plant is now found worldwide in fields, on roadsidesand in wet sites Munz,1959; Hickman, 1993!. It wasreported from New Yorkby 1803,possibly having escaped from cultivation as livestock fodder and grain Mills et al., 1993!.Robbins et al. 941! reportedit as "the most troublesomeweed in Californiarice fields," present since the start of the riceindustry, and foundin all agriculturalsections of the stateand alongstreams and ditches,Madrone Assoc. 980! describedit as a typicalmember of thenontidal community in theDelta, and Atwater 990! foundit on thebanks of 4 outof 6 isletssurveyed in theDelta. A singleplant may produce as many as 40,000 seeds Robbins et al.,1941!.

Festucapratensis Hudson [POACEAE]

SYNONYMS; Festuca elafior Linnaeus

MEADOW FESCUE Nativeto Europe,meadow fescue isgrown for forage and is foundescaped from cultivation in fields and wasteplaces in the easternU. S. and most of California. Munz, 1959; Hickman, 1993!. Atwater et al. 979! list it ascommon in thelandward fringes of tidalmarshes around San Pablo and Suisun bays.

Hordeummurinum Linnaeus ssp, lepinorum link! Arcang.[POACEAE] SYNONYMS:Hordeum lepinorum Link

HARE BARLEY Appendix 7 BJ Page A 1-]1

Harebarley is native to Europe and is found in moist, generally disturbed sitesin easternU. S.,northern Mexico, British Columbia, and California Munz, 19$9;Hickman, 1993!. Atwater et al. 979!list it ascommon in thelandward fringes of tidal marshesaround San Pabloand Suisunbays.

Polypogonmonspeliensis Linnaeus! Desf. [POACEAE]

RABBIT'S-FOOT GRASS,ANMUAI. BEARI7GRASS Rabbit's-foot grass isnative to southern and western Europe and widespread andcommon in NorthAmerica including California, along streams and ditches and inother moist places Munz, 1959; Hickwnan, 1993!. It islisted by Atwater et al. 979! ascommon in thelandward fringes of tidalmarshes around San Pablo and Suisun bays,and it isreported ascommon inthe Delta Madrone Assoc., 1980; Herbold ik Moyle, 1989!, APPENDIX 1 C!. DESCRIPTIONS OF INTRODUCED TERRESTRIAL MAMMALS REPORTED FROM THE SAN FRANCISCO ESTUARY

Felis felis

HOUSE CAT In theSouth Bay, feral have frequently been observed foraging in salt marshes,along salt pond levees, and wading at the edge of tidalsloughs Foerster & Takekawa,1991!. Feral cats may be a majorpredator of smallbirds and marnrnals. An analysisof stomachcontents of feralcats in theSacramento Valley found occasionalremains of waterfowlincluding pintail ducks, mallard or closelyrelated ducks,coot, and a greenheron Hubbs, 1951!. They have killed adult light-footed clapperrails Foerster& Takekawa, 1991! and at least one California clapper rail Takekawa, 1993!. TheSan Francisco Bay National Wildlife Refuge in theSouth Bay began a predator managementprogram in May, 1991that includesthe removalof feral cats. Takekawa, 1993!.

Mus musculus

HOUSE MOUSE Thehouse mouse is native to Europe.It is commonin theDelta in riparian habitats Herbold & Moyle,1989!, and in saltand brackish marsh in SanFrancisco BayQosselyn, 1983; Harvey et al., 1992;BDOC, 1994!,

Rattus . norvegicus

NORWAY RAT TheNorway rat is nativeto Europe,and was established in many areas in Californiaby the mid-1880s BDOC, 1994!. It is common in the Delta in riparianand marshareas Herbold & Moyle,1989!, and in SanFrancisco Bay in saltand brackish marshand diked areas de Groot, 1927; Foerster & Takekawa, 1991, Harvey et al., 1992!.Norway rats will feed in saltmarshes, where they are often observed during thehighest winter tides gosselyn, 1983; Foerster & Takekawa,1991!. DeGroot 927! listedthe Norway rat asthe third most important factor in the declineofthe California clapper rail afterthe destruction ofmarshes and hunting!, statingthat "the Clapper Rail has no more deadly enemy than this sinister fellow. Norail dares nest on a marsharea which has been dyked, for as surely as she does thisvicious enemy will trackher down and destroy the eggs. Many nests have I 'tppend~z1 C! Pag

Vutpes vulpes regattas

RED FOX

SYNONYMS:Vulpes fulva

The red foxes in California are probably descendedfrom Iowa or Minnesota stock. They were either intentionally introduced into California by hunters or they escapedfrom commercial fox farms in the Central Valley in the last half of the 19th century, with a population reported from the southern SacramentoValley in the 1S70s BDOC, 1994!,Red foxessubsequently spread to the coast, reachingthe east Bay areaby the early 1970s Harvey et al., 1992!,and are now common in the Central Valley and in coastalcounties from Sonomasouth. They were first observed at the San Francisco Bay National Wildlife Refuge in the South Bay in 1986,and have continued to expand their range around the Bay, invading by 1992 Harvey et al., 1992!,Wey are regularly seenin the South Bay in all habitat types, and dens have been found in levee banks and salt rnarshes Foerster & Takekawa, 1991!. Impacts from this predator could be substantial, as it has been estimated "that a family of trio adultsand five pups would requireabout 317 pounds of food during the 12-~veekwhelping period" Harvey et al., 1992!.In San FranciscoBay the red fox has prey ed on the eggsand sornetirnesthe young or adults, and disrupted nests or colonies,of endangeredCalifornia clapper rail, leasttern and snowyplover, and of Caspiantern, black-necked stilt and avocet,It may alsoprey on endangeredsalt- rnarsh harvest mouse,the salt marsh wandering shrew, and California black rail in the Estuary.In southernCalifornia the red fox haspreyed on endangeredlight- footedclapper rail andCalifornia least tern Foerster& Takekawa,1991; Harvey et al 1992; Takekawa, 1993;BDOC, 1994!. The SanFrancisco Bay NationalWildlife Refugebega~ a predator rnanagernentprogram in May, 1991that includesthe trapping and killing of red foes Redfoxes control has been Practiced at SealBeach National Wildlife Refuge to protectleast tern and light-footed clapper rail since19S6 Foerster & Takekawa,1991, T,kekawa, »93! Page A2-1

APPENDIX 2. EARLIER INOCULATIONS INTO THE SAN FRANCISCO ESTUARY AND NEARBY WATERS

Native Date Planted Species Range or Collected Comments references!

INVERTEBRATES Porifera Trtilla sp, n Atlantic early C. Hand, pers. comm.; W. Hartman, pers. 1950s comm1977!. Cnidaria Hydrozoa Campanu!aria gelatinosa 1859-1912 Agassiz, 1865;Torrey, 1902;unpublished NMNH records!. Ha1ocordy le dist icha n Atlantic 925, Reportedby Fraserin 1925 asPertrtaria tiarella! 1944-47 withoutgiving a dateof colJection,Reported on fouling panel as Pennariasp.! at Mare Island Naval Basein 1944-47 US Navy, 1951!, Turritopsis nrt!ircola n At]antic 925 Reportedby Fraserin 1925without givinga date of collection. Undated material at NlviNH labeled "probably from Oakland," Listing by Light 941! and Reesk Hand 975! probably based on these earlier, undated records. Ann elida Polychaeta Sabellarta sp>rtn!osa n Atlantic 1932-37 Collectedby Olga Hartman betweenPoint Richmond and Alameda Carlton, 1979a!. Mo1 I us ca; Bi v al vi a Anadara transr ersa, Dead shells of these bivalves collected in the 1.nnarca Ot alis, Atlantic Bay were probably brought in with Atlantic Aequiipec ten t rradians, oysterseither as dead shellsor as living Ananrr'a sintplcx organisms that failed to becomeestablished. Crassostrea gigas Japan 1932-39 Planted in largenumbers in the Bay during this JAPANESE OYSTER period but, despite occasionalreproductive success,never became estabbshed. Some experimentalplantings since the late1950s. Carlton, 1979a!. Crasse>trea tirginica 1869-1940s Planted in largenumbers in the Bayduring this ATLANTIC OYSTER Atlantic periodbut neverbecame established, Some experimentalplantings since. {Carlton, 1979a!. Mercenaria rncrcenaria 1901, 1968 Dead valvesand living specimenscollected m QUAHOG Atlantic the Bay Keep,1901; Carlton, 1969!, Ostrea angasi Australia about 1891, On at leasttwo occasionssmaH quantities of this New before 1963 oysterwere imported to andpossibly planted in Zealand the Bay. Carlton, 1979a!. Ostrea cttilensis Mexico 1868-70, Thisor anotherspecies of southernoyster was 1897-99 importedto andpossibly planted in the Bay. Skinner, 1962; Carlton, 1979a!. Osfrra cdulis 1962 Experunentalplanting of lessthan 300oysters EU ROPE AN 0YSTE R from Milford, CT Carlton, 1979a!. Appendix 2 Page AZ-2

Naive Date Planted Species Range orCollected Comments references!

Arthropoda: Crustacea Decapoda Calhnectessapidus 1897 162crabs planted inthe Bay Vogelsang gr BLUE CRAB Atlantic Gould,1900!. Sporadic reports of blue crabs from BayArea waters in recent decades. In 1994, one crabreported atthe Tracy pumping plant in the Delta S. Siegfried, pers, comm., 1994!, Homarus americanus nw 1874-88 1873shipment lost in trainwreck, In 1874four AMERICAN LOBSTER Atlantic egg-bearingfemales of 150 shipped! from Massachusettswereplanted in theBay, Four othershipments planted from San Francisco to MontereyBay; several lobsters later caught by Montereyfishermen Shebley, 1917!, Limulus polyphemus nw 1880s?, Singlespecimen collected from Bay in 1917. In HORSESHOE CRAB Atlantic 1917 1995we received a report of2 crabs caught and releasedinthe Central Bay whose description matchedthat of L. polyphemus Scofield, 1917; Carlton, 1979a!. U pogebiaaffi ni s n Atlantic 1912 2 malesand 2 femalesof thiscommon Atlantic MUD SHRIMP specieswere dredged by the Albatross in the CentralBay Williams,1986!. VEIt TEBRATES Fish Amblopliles rupestris eUS 1874 Fouradults from Vermont planted in Napa ROCK BASS Creek Shebley,191TI- Anguilla roslrata 1873, 1879, COMMON EEL In 1873,12 freshwater eels from Hudson River Atlantic 1882 plantedin SacramentoRiver, and 1500 saltwater eelsfrom New York Harbor planted near Oakland,In 1879, 500 eels planted in Sacramento River.In 1882,10eels from Shrewsbury River, NY plantedin SuisunBay Snuth,1895; Shebley,1917!. In 1964and 1994, one specimen caughtin Deltain eachyear Skinner,1971; S. Walker,pers. comm., 1994!. Chanos cyprinella Hawaii 1877 AWA 100fish planted in tributarystream in Solano County Shebley, 1917!. Luciusrnasquinongy midw U S 1893 93,000fry from Chatauqua Lake, NY planted m MUSKELLUNGE LakeMerced, SanFrancisco tocontrol carp Shebley, 1917!, Perca jlovescens mid w U S 1891-1950s YELLOW PERCH Fishplanted in riverstributary tothe Delta in gr 1891and 1908; were widely distnbuted by 1918; Canada extinctin the Delta by 1950s; are today present inKlamath River and Tule Lake systems in northernCalifornia Shebley, 1917;McGinnis, 1984;Herbold k Moyle,1989!. PageA2-3 Appendix 2

Native Date Planted Species Rangeor Collected Comments references!

Soimo salar 1874, 1891, In 1874,305 fish from PenobscotRiver, ME ATLANTIC SALMON Atlantic 1931 plantedin SacramentoRiver near Redding. In 1891,194,000 fry plantedin TrinityRiver. In 1931,55,000 fish planted in Smithand Mama> Rivers Anon,, 1932!. Stizosfedion vitreum eUSk 1874 16adult pike from Vermont planted in WALLEYED PIKE Canada SacramentoRiver near Sacramento Good son, 1966!. Tautoga onitis 1874, 1897 A few hundred fish plantedin the Bay TAUTOG Atlantic Shebley,1917!, Tlrymallus art<'cps n central 1904 and 600grayling from Montana washed into the ARCTIC GRAYLING US& later SacramentoRiver when a pondwall at the Canada SissonHatchery burst. Additional plants were made in the Sierra Nevada, but never became established Shebley,1917; McGinnis, 1984!. PageA3-7

APPENDIX3. DESCRIPTIONSQP INTRODUCED PLANTS AND INyERTEgRATESIN AREAS ADJACENT TO THE SAN FRANCISCO ESTUARY

PLANTS

VASCULAR PLANTS

Ludwigiapeploides var, morttevidensis Spreng.! Raven [ONAGRACEAE]

WATER PRIMROSE, FALSE LOOSESTRIFE

SYNONYMS:Jussiaea repens var. montevidensis Jussiaea montevidensis Ludwigia uruguayensis Native to southernSouth America and introduced to Europe,Australia and thesoutheastern U. S,,water primrose is found on low elevation lake shores and stream banks in much of cismontaneCalifornia including the Central Valley Hickman, 1993!.

Nymphaeamexicona Zucc. [NYMPHAEACEAE]

YELLOW WATERULY, BANANA WATERLILLY

Native to the southeasternU, S. and Mexico, the yellow waterlily is found in lakes,ponds and slov streamsin theSan Joaquin Valley It is officiallylisted as a noxious weed Hickman, 1993!.

Nymp!incaodorata Aiton [NYMPHAEACEAE]

FRAGRANT WATERLILY, WHITE WATERLILY Thefragrant waterlily is nativeto theeastern United States and is foundin quietwaters, in pondsand at theedges of lakesat widelyscattered locations in Californiaincluding Butte County in theSacramento Valley, LakeTahoe, and the San Bernardino Mountains area,and is "expectedelsewhere." It is widely cultivated as an ornamental, and is officiallylisted as a noxiousweed Hickman, 1993! Appendix 3 PageA3-2 Polygonumhydropiper Linnaeus [POLYGONACEAE] COMMONSMARTWEED, MARSHPEPPER, WATERPEPPER NativetoEurope, common smartweed wasreported from New York by 1843, whereitwas used tomake a yellow dye Torrey, 1843!. Itis uncommon inwet places fromcentral andnorthern California toWashington Munz959; Hickman, 1993!.

Polygonumpennsylvunicum Linnaeus [POLYGONACEAE]

PINKWEED Nativetothe eastern United States, where itsflowers are an important waterfowlfood, pinkweed isfound inmoist disturbed areasand drying ponds inthe easternSacramento Valley,where it may be planted, and is "expected elsewhere" {Hickman, 1993!.

Polygonumprolificum Small! Robinson [POLYGONACEAE] Nativeto the eastern United States, Polygonum prolificum isfound in wet saltyplaces inNapa County andin the Lake Tahoe area, and "expected elsewhere" {Hickman, 1993!.

Tarnarixspp. [TAMARlCACEAE]

TAMARISK, SALT CEDAR Jepson951! lists one species oftamarisk inCalifornia, Munz959! lists four species,Munz 968! lists seven species, andHickman 993! lists five species Allof thesearenative toEurope, Asiaor Africa. Jepson 951!reported French tamarisk, Tamarixgallica, fromWhite Sulphur Creekin the Napa Valley; Munz 959! reportedathel,Tamarix aphylla,planted inthe Sacramento andSan Joaquin valleys. Dudley& Collins 995!describe aninfestation oftamarisk covering several thousandacresofriparian andupland areasnear the Kern National Wildlife Refuge m theCentral Valley, and note T. chi7ensis, T.ramosissima, T.gallica and T. parvifloraasintroduced species posing a serious, documented threatto sensitive species or ecosystemsin California. Appendix 3 Page A3-3

Alisma tanceotatum With. [ALISMATACEAE]

Native to Eurasia and northern Africa, this member of the water plantain family hasbeen introduced to Chile,Australia, Oregon and California.It is reported from ponds, rice fields, ditches and slow streamsat low elevations in northwestern California, Sonoma and Marin counties, the northern Sierra Nevada Foothills, and the SacramentoValley Munz, 1968;Hicktnan, 1993!.

Aponogetortdistachyon Linne [APONOGETONACEAE]

SYNONYMS:Aponogeton dtstachyus

CAPE PONDWEED

Cape pondweed,native to southern Africa, is widely cultivated for aquaria, often escapingbut rarely becomingestablished. It is reported from low elevation ponds in the southern Coast range and the Bay Area, and is "expectedelsewhere" Munz, 1968; Hickman, 1993!.

Cyperusdifformis Linnaeus [CYPERACEAE]

This plant is native to the Old World and has been introduced to Mexico and Virginia. It is found in low elevation ditches, rice fields where it is a seriouspest! and pond shores in southwesternCalifornia, in the Coast Range in Sonoma,Napa, Marin and San Franciscocounties, and in the Central Valley Munz, 1959,1968; Hickrn an, 1993!.

Echinocloaoryzoides Ard.! Fritsch [POACEAE]

SYNONYMS:Echinoctoa oryzicola var. mutica

Native to Eurasia,this plant is reported from rice fields in Butte County Munz, 1968!and rice fields and wet placesin the southern SacramentoValley Hickman, 1993!.

Eteocharispachycarpa Desv. [CYPERACEAE]

Native to Chile, this plant is found in Nevada, in coastalsalt marsh in Humboldt County, and in vernal pools in Amador and El Dorado counties in the Sierra Nevada Munz, 1959;Hickman, 1993!. Appendix 3 PageA3-4

Fimbrisfylismiliacea Linnaeus [CYPERACEAE] Thisis a widespreadalienthat is native to the Old World tropics. It is found inlow elevation ricefields inthe Central Valley, and was collected inthe Bay Area in 1866 Hickman,1993!.

Heferanfheralimosa Schwartz! Willd. jPoNTEDERIACEAE] Nativetocentral andeastern U.S. and tropical America, thisplant isreported asuncommon in rice fields at low elevations inthe Sacramento Valley. It is an annual,generally growing emergent inwater oron wet ground, andsubmerged asa seedling Hickman,1993!.

Hydrillaverffcillafa Linne! Caspary [HYDROCHARITACEAEj

HYDRILLA NativetoEurasia orcentral Africa, hydrilla isa highlyinvasive aquatic plant thatclogs waterways, interferes withnavigation, anddisplaces nativeplants. It was firstobsess edin the U. S. in western Florida in1958 or1959, presumably introduced asdiscarded material fromaquaria orescaped fromcultivation forthe aquarium tradeOoyce, 1992!, became established inthe southern United States andCentral America,andhas been found inTexas andIowa. Itwas first collected inCalifornia inOctober 1976at Lake Ellis in14farysville, andby 1977 was reported fromtwo small pondsinSanta Barbara andRiverside counties,from Lake Murray nearSan Diego, IESP,andfrom1991!. the All American Canalin the Imperial Valley Yeo & McHenry,1977; Onlyfemale hydrilla plants have been found inNorth America, which propagatebystem fragments, budsand tubers. Dormant propagules maysurvive in thewater ormud forseveral years.Hydrilla's useinaquaria mayaccount inpart for itsrapid spread, anditmay also bespread byboat trailers andpossibly bywaterfowl Yeo& McHenry,1977!. lakesatHickmanlow elevations 993! reportsthroughout hydrilla muchfromof' ditches,cismontane canals,California, ponds, reservoirsincluding and the SacramentoValleyandthe Delta. Thomas pers.comm., 1994!,however, reports thathydril]a isnot in the Delta waterways, andit was not found inthe Delta in surveysconducted bythe California Department ofWater Resources and DepartmentofFood and Agriculture IESP, 1991!. In1977, theCalifornia Department ofFood and Agriculture classified hydrilla asa ClassA noxious weed.Hydrilla may have been eradicated fromLake Ellis and LakeMurray, andthere arecurrent efforts tocontrol itat Redding onthe SacramentoRiver Thomas, pers.comm,, 1994!. Inthe 1970s, thestate of'Florida spent56to SS million a year onhydrilla control Yeo& McHenry,1977!. Appendir 3 PageA3-5

Najasgracillima A. Braun!Magnus [HYDROCHARITACEAE]

THREAD-LEA VED WATER-

Native to the northeasternU. S., thisplant is reportedas rare in low elevationrivers in the northernSacramento Valley, but "expectedelsewhere" Hickrnan, 1993!.

Najas gramineaDel, [HYDROCHARITACEAE]

RICE-FIELD WATER-NYMPH

Native to tropical Asia, this plant is reportedas very uncommonin low elevation irrigationditches and rice fieldsin Butte and Colusacounties in the SacramentoValley Munz, 1959;Hickman, 1993!.

Ottelia al~smoides Linnaeus! Pers. [HYDROCHARITACEAE]

Native to Africa,India and the southwesternPacific, this plant is describedas a potentially noxiousweed. It was found in low elevationditches and rice fieldsin ButteCounty in the easternSacramento Valley, and is presumedto be eradicated Hickman, 1993!.

Pelion!>drat'irgi~iica Linnaeus! Schott & Endl, [ARACEAE]

TUCKAHOE, GREEN ARROW ARUM

Tuckahoe is native to eastern North America, and is uncommon in low elevation ponds and reservoirs in southwestern San Joaquin Valley Hickman, 1993!.

Scirpus mucronatusLinnaeus [CYPERACEAE]

This plant is nativeto Eurasiaand introducedto centraland easternU. S. and California, ivhereit is a weedin rice fieldsand wet placesat low elevationsin the SacramentoValley, the Bay Area and the Coast Ranges Munz, 1959;Hickman, 1993!. Appendir 3 Page A3-6

Scirpustuberosus Desf. [CYPERACEAEj

SYNONYMS:Scirpus maritimusvar. tuberosus

Native to Europe,this plant is cultivatedfor waterfowl food and has been introducedto easternNorth America and thePacific coast from Californiato Oregon.In Califorruait is reportedfrom low elevationditches, marshes and rice fieldsin theCentral Valley and Bay Area Munz, 1959; Hickrnan, 1993!.

INVERTEBRATES

MOLLUSCA:GASTROPODA P1anorbelladuryi Wetherby,1879! [PLANORBIDAE]

SEMINOLE RAMS-HORN SYNONYMS:Seminolina duryi Thissnail is native to Florida and has been spread bythe aquarium trade, with thealbino form sold as the "red ramshorn." It is commonin southern Californiaandnorth near the coast toHumboldt County, reported especially from artificialponds, drainage andirrigation ditches, andthe outflow from warm springs. Thefirst California record is fromSan Bernardino County in 1931.It is unclear whetherit occursin thestudy zone Taylor, 1981!.

Pseudosuccineacol ume1la Say, 1817! [LYMNAHDAE]

MIMIC LYMNAEA

SYNONYMS:Lymnaea colume11a Thissnail, native to theeastern United States, is common in artificialand naturalponds, irrigation ditches, creeks and rivers in centraland southern California.The earliest California record isfrom an irrigation ditch in Calaveras Countyin1921. It is unclear whether it occurs within the study zone Taylor, 1981!. Appe~djx 3 Pagr A3-7

Radixauricutaria Linnaeus, 17S8![LYMNAEIDAE]

SYNONYMS:Lynrnaea auricutaria Hanna966! reportedthis European snail, which is now widespreadin the UnitedStates, from irrigation systems and natural bodies of waterfrom Sacramento to LosAngeles counties, including Napa, Santa Clara and Alameda counties. It is unclearwhether it occurswithin the study zone.It apparentlyhas spread from artiftcialponds in metropolitanareas. The first Californiarecords are from ornamentalponds in LosAngeles, where Gregg 923! first noticedthem in 1922and wastold theyfirst occurredabout 1920, and from theJapanese tea garden in Golden GatePark, San Francisco and the fountainpool at ByronHot Springs,Contra Costa Countyin 1924 Hanna k Clark,1925!. It hasbeen suggested that it mayhave been introducedas snailsor eggson ornamentalaquatic plants, or throughthe aquarium trade, where it was sold as the "African or Paper-she/ledSnail" Gregg, 1923;Hanna & Clark, 1925!. PageA4-1

APPENDIX 4. INTRODUCED ORGANISMS IN THE NORTHEASTERN PACIFIC KNOWN ONLY FROM THE SAN FRANCISCO ESTUARY OR ITS WATERSHED

Dates are marked as in Table 1.

Species Dates of First Records Comments

PLANTS

Seaweeds Bryopsis sp. 1951 Codium fragile tomentosoides 1977

Vascular Plants Salsola soda 1968 a few plants found in BodegaBay in 1994, but none in 1995 PROTOZOANS Anc!'strum cyclidioides 1946' 894I Boveria teredinidi 1927' 913! 5phenophyra dosiniae 1946' 894j Mirofolliculina limnoriae 1927' 871! Trochamn!ina hadai 1991'

1NVERTEBRATES

Porifera Prosuberites sp. 1953'

Cnidaria Blackfordia virginica 1970 Napa River only Cladonema uchidai 1979 Clava muiticornis 1895 Corym orpha sp. 1955-56 Garveia franciscana 1901 Maeotias inexspectata 1992 Napa tntPetaluma rivers only Aurelia "aurita" 19897' South Bay only?

Annelida Branchiura sowerbyi 1963' [1950'] limited to watershed Potamothrix bavaricus <1965 Tubificoi des apectinatus 1961-62' Varichaetadrilus angustipenis 1982 limited to watershed Ficopomatus enigmaticus 1920 Marenzelleria viridis 1991 Po t a mil la sp. 1989 Sabaco elongatus 1950s' Appendix 4 Page A4-2

Species Dates of First Records Cornrnents Moll u sea:Gastropoda Busycotypuscanaliculatus 1938 Crepidulacontrexa 1898 Littorina saxahlis 1993' ErneryvilleMarina only Boonea bisuturalis 1977' Cuthona perca 1979 LakeMerritt only Eubranchus misakiensis 1962 Sakuraeolis enosimensis 1972

Mollusca: Bivalvia Pola rnocor hula am u rens is 1986 Artbropoda:CrLrstacea Eusarsiella zosteri cola 1953' A ca r tie!la si nensis 1993 Lim n oi th ona sin errsis 1979 Limnoi thona tetraspina 1993 Oithona davisae 1979 Pseudodiaptomusforbesi 1987 Sinocalanus doerrii 1978 Tortanussp. 1993 Epinebalia sp. 1992 Acarrthomysis aspera 1992 Acanthomysis sp, 1992 Deltarnysis holmquistae 1977 Dynoides dentisinus 1977 Eurylana arcuata 1978 Paranthura sp, 1993' Gammar us dai beri 1983 Leucothoe sp. 1977 Melita sp. 1993' paradexaminesp, 1993 Transor chestia enigrnatica 1962' LakeMerritt only Eriocheir sinensis 1992 Orcorrectes virilis <1959 j1939-41! limited to watershed? Arthropoda:Insecta An r'solabis rnaritima 1935[1921] 920! reportselsewhere probably in error Xeochetina bruchi 1982 Neochetina eichhorn jae 1982-83 Trigonotylusuhleri 1993' Kntoprocta Llrnatella graci!is 1982-84[1972] Bryoz oa Victorel! a panida 1967' LakeMemtt only? PageA5-1

APPENDIX5. INTRQDVCED MARINE, EST Q !RGANISMSIN F !Vg~~~IONAL STUDIES

Mills et al., 1995 ThisStudyb

PLANTS Bacteria 1 1%! 0 9 ]8%! 0 0 Phytop lankton 17 ]2%! 05 02/o! Seaweeds 7 5%! 8 16/o! Vascular Plants 59 42%! 4 /o! 97 63%! 49 { 20%!

PROTOZOA 2 1%! 0 0 8 3%!

IN VE RTEB RATES Porifera 0 0 5 2%! Cnidaria 2 1%! 2 4/o! 0 2 ]%! ]7 7%! P latyhe lrnin thes 1 1%! 0 0 0 0 0 Nernatoda 0 1 2%!

Annelid a 3 2'/0! 2 4/o! 1 1%! 21 9%! Mo! lusca 14 0%! 6 12%! 19 12%! 30 13%! Arthropoda: Crustacea 6 4%! 22O/o! 6 4%! 49 20%! a: In secta 2 1%! 0 0 4 2%!

Entoprocta 0 2 1%! Bryozoa 0 0 1 2%! 0 0 11 5%! Chordata: Tunicata 0 8 3%!

VERTE8 RATES Fish 25 18%! 4 8/o! 29 19%! 28 12%! Amphibians 0 Reptiles 0 0 0 ] ] Birds 0 0 2 4ao! 0 0 MammaLs 4'/o ! 0

SUBTOTAL: Plants 84 60%! 19 38ojo! 97 63%! 54 23%! SUBTOTAL: Protozoa 2 1%! 0 0 8 3%! SUBTOTAL: In vertebrates 28 20%! 23 46'/o! 28 18%! 147 61%! SUBTOTAL: Fish 25 18%! 8 ]6/o! 29 19%! 31 13%!

TOTAL 139 ]00%! 50 ]ppo/ ! 154 00%! 240 00 /0!

Less than 0.5%.

Jansson not reportspecific cnterta for inc]usiono~ th zone,but reportedonly two vascularplants, both of the Basedonthe expanded list,as explained inthe "T~p . 'l p