Intertidal Diatoms from Willapa Bay, Washington: Application to Studies

Home , Willapa Bay

EileenHemphill-Haley, U.S. Geo ogrca Survey at 1272Department of ceologcal Scences. Universty of Oregon EugeneOregon 974A3 1272

IntertidalDiatoms from Willapa Bay, Washington: Application to Studies of Small-ScaleSea-Level Changes

Abstract

.sea]ere1leconstnt]ti.lisusiilg(]stUaril. thedjstrjbutionsofmoderniItertida]s|..iljS'{SIlattl)|anon.goings|ud1torussessthebiostlatig .ha|lgcslrjgg{.(ible!rlhquakesnithe|aci1icNord]$est.on)d.jf|inLl.|Lill! tn \\ illapa t3ar. \nashington. Q mode frctor rnah sn iros used t0 rta*ii1- assiJnblas,,s lrom lnlal fllts and boks. shallo* srbtirlal chaMds. lx and high nrurshes along tro inre id:il traDsecc on the \iariakunr Rircr. and in intertirlal sarnples fron dre open ha!. Auto.h oh,n,s raxa rlorninat(1 thc ussr:mbiages. hut in some cases pnrhahle alk,rhthorous tuu scordl relarireh high in rhe

.I.lj.r.stl|s.l|hlja|ltYsiSsuggeststhatdiatomscanbeusedtoir1enLi|rLlrnrlr ilaG.(|hannllb!nks'udsh!||oi{Sub1olchannels.belorapproxirnatlm'anlo$(]thjgh\'uLer(MI,H marel'- be ee. ['ll.H$ unrl rran fisho high $rLter {}IHHS]: and {3) high narsbr:s apprxirrrclr bctwccn X'lHH\i rurl ertreme high water iEH\\1. lhc marsilur,hn,l rransirion. near F:Htr. coincides wirh the terminrrs ofrcsularrJiaLon ptuhrcriir' lnd is recos nizable br the disappearance of high marh diatona in soil .li,tl)sirs. dbsolute elerations ofthe ecobgn:al zon.s an, (!'rstrline{l br lo.al tidal range.Becruse ofthe cosmopolitardistributions of n,lnl,l Lhcspocies observed in this studv. thesedata at pn,bab r applicatrle to sturlies of Quaternar,r sea-lere1 rhangc !rd fali,oscismicirv throughour the coastal Pacilic \orth$cst.

Introduction along the Cascadiasubduction zone. the boLrnd- ar'_ betwccn thc de I'uca plate and the over- Thc purpose ofthis stud_vis to identify cliatom taxa Juan riding North America plaLe (Figrrrc l). rssociated with verticallv distributcd cstuarinc rvhereas deposits (i.e., high rnarshcs,low marshes,tidal othcrs arc bclicved to have been caused br clis- flats, sloughs.and banks) that can be used to recon- placementson shallowcrustal faults (Nelson. 1992; struct small-scale (< 3 m) palco-sca-lcvel changes Bucknempi ol.. laq2; \elsorrarrd P, r-,,rriu.. in llrt, rl to 1'Jeo.ei-micit\nr cu:tatirlro, c-sFi in prcss). Coseismic landJevel changes rnar result in the Pa, ifir'\orthrrr'1. Tlu'itiurr: betrreenrnarine sudden subsidcncc(e.g., Plalker, 1969; Atrvater, ancl freshwater diatoms in co:r.stalcleposrts are com- l9B7:. 1992; Darienzoand Pctcrson. 1990: Nel- monlv used to identify rnajor transgrcssionsand son, 1992; Clarke and Carver, 1992) or uplift regressionsof Quatcrnarr sea level (e.g.. Palmer (Plalker, 1969; Bucknam et al., 1992) of coastal and Abbott. l986; llronen et al.. 1987). but the and estuarinesites. The ecologicalconscquences recognition of srnall-scalcchangcs in paleo-sea-leve1 inr.olveeither a rapid rise or llll in relativc sca lcvcl mrr-tb, Lc-ed on more -uhtle clrange-irr r, rti- strch that vegdatcd dreasnormallv above the reach callv distributedasscmbl:ges. Such studiesare in- oftides are suddenly inundalcd. or-conversely,nor- variably hindered bv the paucitv of detailed data mallv intcrtidal sullaces are elevated out o[ the in- reearLlirrgthe rn, rl.rn,li-triLuliuns ulpedinent I'rra (e.g.. Eroncn er ol., l987). tertidal zone. Estimalesof coseismicsubsidence r:aused bv the earthquakc about 300 years ago CompelJingstratigraphic. evidcncc now suggests range liom about 0.5 m (Clarke and Carr,cr; 1992; that some changcs in relative sea-level in the Pa- Da|ienzo and Pctcrson, 1990) to 2 m (Atnater. cilic Northwest drrling the l{oloccnc mav har.e 1987; Atwaterand Yamaguchi,1991). This range resuitedfrom large earthquakes,inclucling a rno- in clcvatioral change tould be enough ment magnitude (XI.)) {} event as rcccntlv as about to quicklv i300 years ago (Atrvatcr.1987, 1992r Darienzo transforrn a lorvland coastal meadow or forest inlo and Pctcrson. I990; Attater and Yamaguchi. a tidal flat. Basccl on strati;paphic and biostrati- l99l: Att'ater er al., 1991; Nelson, J992: Clarkc graphic evidence in south*estern Washington, this an,l Can.r. lqq2. \, l.un .rnd Per-orriu-.in lre..: process mav havc bccn repeated at least six times Clague and Bobrowsky, 1994). Some of the in about the lasL 3500 ycars (Atvater, 19BB: palco-ea hquakcs have been attributed lo fopture Hcmphill-Hale,v. unpub. data).

\orlhrvest Science.Vol. 69, No. l. 1995 29 t 24'1svv

|igun. 1. \tl illupr Bav. a nisotidal ,istulri iii sodth{estern Washhgton. -samphrg localities: BC Bav Center tidal llat: BR Bone Rivir tidal n!L: \l-traDse(r Nl. l,^'er Nia$ialum Rirer; -sP Stonl Point; Nu bansect \u. upper Niairiakun Riveu '1t'- li,L. l'(,nrr.

Various kinclsoI coastalcnvironmenls can be Riznyk and Phinney. 1972; Rizn_,-k,1973; l\lain idcntficd bascclon thc classificationolcliatoms into anclMcJntire. 1974; Moore and McTntire,1977; ecologicalgroups (Vos rnd clcWol[. 19138;1993; Amspoker and Mclntire, J97B). but othcl than Kosugi. 19BB). ln this papcr. Q-modcfactor anal- \el-on rn,l Kr-himr t 19031.rlifference- in a--em vsis is uscd to clustcr samplcswith similar diatom blages betrveen tidal llats, marshes. and uplands asscmbllgcs from thc modcm surfacesoftidal flats, have not been documented. and there are no such intertidal ri,'er banks. shallowsrrbtidal channels, pre\.ious studies fbr coastal south$'estern low rnarshes, and high marshes in northern Wil- Washinplon. lapa Bay. WashinSon (!igure l). Upland samples. iound to be barren of in situ diatonrs.were ex- Background cluded liom the factor analvsis. GeneralEco ogical Zonat on Reative to T da Studies ol modern estuarine diakrms have LEVEI (i.e.. shown lhat manv taxa are cosmopoiitan have The mixed tides oi the Pacilic coast along south- (Mclntirc a rvorldrddc clistlibution) and frloorc. wcstcm Washinlfon cause a fairly predictablc 1977; T,vnni. l986) and usuall,vcxhibit bloadcr thrcc-ticrcd ;ntcrtidal zonation.with lowcr inter'- tolcranccs for salinity (Xloorc and Mclntirc. 1977; ticlal flats. "lot"'marshcs. and "high" marshcs Mclntirc. l97B; Amspoker and Mclntirc, l97B; (Macdonald, 1977at Macdonald and Barbour. Admiraal. 1979) than ltrr othcr factorssuch as ex- 1977; Frc,v and Basan. l9B5). Thc clcrational posL.rre(Caslenholz. 1963; Sullivan, 197tl) and rangesof thesc zonesdepends on the local tidal subslrale (Amspoker and N{cIntire, 1978; Whit- range, $hich vades both along the r:oastin the Pa- ing. I983: Whitingand Mclntirc.l9B5: Kosugi, cific Northvest and t'ithin individual estuaries. In 1987). A series of er:ologicalstudies in Oregon Willapa Ba,v,thc tidal rangc bctwccn mcan high documented the rnodern r.ertical distributions of r,ater (MHS ) and mean lorv waler (llLS ) rangcs attached or sediment-associatedspecies in thc from 2.3 m ncar thc mouth of the estuaryto 3.4 lower part of the intertidal zone (Castenholz,1963; m at jts soulhcrnmostrcachcs (Nlajor, l9B9).

:'i0 Hemphill-Haley Thc initiation of lorv mamh \'rgetation in thc Pa matelr 800.500, and 200 m liom shore. resJrec- 'l'he cific Northu'estis approximatelyecFivalent to lhe tivciv. llat is vegetated rrilh sparse Zosterz r:lo'ation of mean lower high water (l\{T,HS ) (Mac- rdrra al the locat;onsof samplesB(l 2 :rnd BC-iJ. donald and Barlnur'. 1977) ancl cxtends to approx- -qaml)lesBR-l unclBR-2 r'ere collectedffom thc irnatel;-rncan highcr high t'ater (SIHHW). although Lrnlcgetatedsu ece of a siltv tidal flatnorthofthe lcgctrtion is genefallvthicker betwccn mcan high Bone River, approximatcl,-v150 and 300 m fitrrn uaLer'(N'[HS ) and frlHHW. Low marshesare com- shorc. Samplesrrere collected lrorn thc marsh and monlv suhmergedoncr: cach tidal dav (l'rev and adjacenLticlal tlat at Ston,vPoint: SP-l and SP-2 Basan.l985) and thus supportmacrophvtcs cupa- are liom tlre un,regetatedflat; SI'-3 is from the flat ble of legular subrnergt:ncc.Sa,vce (l9BB) lisred adjacenL to a Jratchcrf Tiglochin mo.itino: SP-A the dorninantlol-marsh macrophvlesin S illapa is frorn a lot' marsh thicklv regetaLedwith Tnglo- chin maitinn ancl Salirnmio t:irginica; and SP-5 Bav trs ^Salicorzia rirgi.niut. Jou.nrea camosa. 'Ihglochi.rt is lrom a high marsh marititrtu. nnLlPlantago mtLtitima. High in a thick stand ol Potentillo. pu,i.liro-3 m liom tlr" ha-- nf r Pl, i-tu,nne ter m rshes e\tend liom NIHHST to nc:l crtreme high race. Samplcslvcrc collected liom a marsh and water (EI{S ) (l'lacdonald ancl Barlmur. 1977) anrJ tidal slough at Toke Point : TIJ-I is from the 1loor are slrbmerge.l only (luring highcst spring tides and o[ a sardr tidal slough colered $,ith Ztttertt m.a- -ctorrnsurgcs. According to l-re1and Basan(1985), 'll'2 dna beds; from a l-m-diamctcr patch oi high m:tshes are prone to desi

Tntcrticlal f)iatoms frorn Srillapa Ba1 3I TranseclNl - lowerNlawiakum River

10-27.5%" Marsh-Upland MEANSALINITY:21 6%" Transition High Marsh TEMP.RANGE:6'22.5" C (tactor5) (tactor1) I Low Marsh {tacto.3) Nt-5 - Nt-4 ChannelBank (tacror4)

- MLLW

ShallowSubtldal (taclor 2) I

02030 DistanceAlong Transect (m)

E %sand E %sitt I %clay

Figure 2 t'.,njl. rlong traDi{! L \1. on rhe lo$er \i!{iakum Rirer. Cranr sire. sdnritv. and rrrnperarure meas,,nin!,nrs rfe for 1990i i,nimsre eri,r i,r ridll datuns is +0.10 n.

lngbei and rare TigLtchirt naitima. Nu ,Xis near recorded,in April I990 at eightsampling srations MHHW. and dominant rnacropbytesare Dirrrclrlir along each transect. Aclditionaldiatorn samples rpi(:ota nrTdDesdnnpsia (:oespitosa.with rarc C. \'!crc collected at thc stations in July, Septembe., hzg6ei. Nu-5, Nu-6, and Nrr-7 are on the gentl,v and Deccmber I990 to tcst for seasonal.r.ariation J,'1,ingmrrnh -ufla,l shcre tlre dnminrnt mcc- ;n diatom distributions. Preliminarv analyses rophvtes are D. cu,espitosaand Potcn.tillapaciJico; sholvedthut relativeabundances ofspecies varied Nu-B is at the highcst point on the rnarshthere amonplsamples collected during different tirnes ol thc dominant macrophytes are,/lrr:rrs balticu.sand the vear. bLlt clistributionsrcmained const nt l'. paa!,u. throughout the year. Thcrcfore. the seasonalcounts were combirredfor this report. Samplcsliom the llelative elevationsalong lransecls\u and NI shallowsubtidal channel of the Niawiakum River wer-errcasured l,ilh a sclfJcr.eling ler,el. r,'hich is wcrc collectedby using a small drcdge deplovecl accuraleto + l cm for both horizontaland verti- from a canoc during low tidc. cal distanccs.Tidal datuns (figures 2. 3) werc cs- timated to be within +I0 crn bascclon 6 l)iatorn samplesconsisted of about I cm3 of the observationsof uatcr levelsat high and low rides uppermost l-2 mm of surfacc sediment,scrapcd during goorJwcather, and comparisonwirh ridal t'ith a srnall spatula from and placed in buffered charls corccted for tidal variation in the cstuarv 2oloftrrmaldehyde in a glass r,ial. All modern in- rl'.reillc(.orrntr l'l.rnningD.l'.rrtment. \rilFn tertidal surfacc samples collected in Willapa tsay crrrnm.. 1990). Diatonr and grain sizesarnplcs rvcre containcdabundant diatoms. somc cxceeding5 x collected. and dornin:rnt rnacropir!Les r!ere l0s cells/cm3.Many o[ thc most prolific spccies,

32 Ilemphill-Hale1 TranseclNu- UpperNlawlakum River

SALINITYRANGE: 2-23 4 %- MEANSALINITY: 14.9 lEilP. BANGE:4-22.5. C Hlgh Ma.sh (factor 1) Hlglvlow Marshtransition

- MHHW g Low Marsh 3 (tacto, 4) 2

1.5 / Channelbank .e 1 (tactor 2) E -g 0.5 ul /, Shallow sublldal / (tactor 3)

10 20 30 DislanceAlong Transecl (m)

Nu-3Nu-2 Nu.1 Nu.S ./. E %sand E si[ I 9. ctay

FigL,rt 3 P(,lile along fans.iir \u on rhe rrqlxr Niawiakun Rivtr. crlin size. saLirih- anrl remperarur ncasuremerts ar: tor l9g0: cslimaled .fior for l dl daru s is +0.10 m. hor'ever. arc dclicate (e.g., small ,\iar;ica1a and sJtcics are based on lhcse observalionsand the I' huonthr't.rrrdhure littl. chan," L,t-urr iring irr detailedanalyses b,v ['hiting (1983) and Main and the fossil recorcl.The disJr:rritvbetueen Lhctvpes Mclntire (1974). Diatomscollected in thc field (er- ol marineplanktonic diatoms obscrvcd in producr- cluding Tokc l)oint samples that dried out) rtcre tive surface natem (e.g.. Chaetoceros spp.. sla;ncdfor e!idence of intactcytoplasm .with Fasl SkeLetonena spp.) and tara that actually survivc (lreen FCF cytoplasm sLain in buflerecl 29lo for- dissolution and burial to becone fossils (e.g., maldehvde. and mounted according 'lhnlrLssionemt to the Taft sytp.and Coscinodrscusspp.) is well Syrup Mount (TSl\{)mcthod (Taft. 1978: Steven- known. The sanc appliesto bcnthic estuarinedi- son. l9B4). lhe refractivc index of the TSNI is aloms. such lhat manv ol the nlosl pnrlific taxa sufficient lor rcsolr.ing the lalve characteristics of make poor fossils (e.g.. MeLtsint spp. and Sledrc mosLdialoms, although thc fine structureof some spp.). r,hcleas some of thc rarer diatomsin mod dclicate sper.ies(thich are lypicallv abscnt in fos- ern deposits (Caloneis s1t1t..Carnpl.Lotttscu.. spp.) sil deposits)mav not bc rcsolvable.Stained sum mav becorne.by virtue ol their rcsilicncero ne- ples can bc rinsed. dried onto a cover slip. and 'lbere[ore, slruction, dependableftrssils. thc lac, mounted with Hyrax, thich improvcs resolution tor analys;sfcrcused on thc rnodern distributions of valve characterislics. of84 diatom taxathat ncre alsoobservcd in Holo- cene fossil dcposits around Willapa llay (Hemphill- At least 400 diatom valvcs were countcd at Halev. 1993a ancl unpub. data). 625x ahng random ,'ertical traversesnear thc mid dle of thc cover sliJr,t'ith magnifications increased Macrophyte samplcs were also collccted lbr to 1250:. to cxamine smaller spccimens (He mplill- qualitativc assessmentoi epiphytic popLrlations: Haley, 1993a). Intact frustules !!{-'rc counted as rclircnces to an epiphvticlile lbrm for indilidual two valves.For the factor analysis,total countsol

Intenidal l)iatoms from Willapa Bay ::i::i livc plus enptv frostules and singilc valr.cs were O. auita and 0. obnuta. Small forrns ol Paralio used to allo\r {or occurrences of both au- rrrlcol.r (lcss than 20 pm diameterJ were countcd tochthonousand probableallochthonous diatorns, separatel-yfrom largc forrns because of evidence as vould natLrfallyoccur in ibssil assemblagcs. thaLvalve size mav be ccologicallv contlolled (Roe- Reierencesto the relatilc abundanr:esol diatoms lofs. l9B4) and obser!ationsthat small forms art: are based on the percentageoi cach spcciesrela- more r,idelv distributecl in lower-salinitv areas ol tive to the total numbcr of diabms counted in each thc csluar,' (Hemphill-Halev. 1993a). samplc, normalized by dividing several dominant Thr results of the lactor analvsis arc bascd on species (,llelosira n on iliforrnis, XI. at m nttLo itl es. the relative abundanccsofd;alom tariain each sam- anclParaLia sulcata) by an ar- S,tnedrafastiatloto, ple. Beginningwith the rat'ccnsus-datamatrix [Xl : ( 0/o: = bitrary factor of l0: ver;- rale 2 rare of n cntit;cs(i.e.. samples)and m r.ariables(i.c.. : 2-4.90/o;frequent = 5-9.9?o; comrnon I0-ill3o/o: taxa). laluc counts rlere transformed to the per' abundant = ) ljllo6. ccntage of the range of total numbcrs for cach vari- Grain size an:ilysesoINu. NJ. BC, and BR sam- ahle.tlrerebr giring r. rnrr,h seighttn rare-pecie- plcs vcrc completerlwith a (iimax H,vdrophotom- with limited distributions as to common spccics lhal eter and Rapid Settling Analvzer (RSA).' are pafiicularlv dominant in cerLainlocalities. The Calibration tests indicate that thc hvclrophotorrre- varimax rotaLionmethod iras used to simplif-vthe ter is precisc to *3olr ancl lhe RSA to +5yo inter?r'etation of factor loadings (i.e., the contribu- (Torresan. I9B7). Scdimcnt texturesSP and TP tions of each samplc b the fac{ors). The vadmax srmples r,rere eslimated in the field. Water tern- firctorJoadingancl lactor-score matriccs provided perature and salinit_vdata along lranseds Nu and by CABIAC list thc contributionsofeach sample Nl verc collcctedfrom the adjacentchanncl ncar and cach laxon to the lbctors, respectivcl,v.Taxa the surface at high tidc using a YSI \lodel 33 lith the highestfactor scoresare indic'ativeofthe S-Cjl mctcr rtith reportedaccuracies of +0.5'C modcrn cnvironmentin thich they are found ci- and + 0.5 pprn, rcspcctivch. Salinit,vdata 1brthe ther becauseof thcir restrictecldistribution or their {,fen ba}- were pro\.idcd b_-vthe Washington particular abundance in that cnvironmenl. The fac- I)cpartment of Fisheries Laboratory dt Nah()tla. tor assemblagesin this report includc both au- Data used lbr this stud,v (liatom counts and tax- tochthonousand suspectedallochlhonous species onomy. grain-size results)are also avaihblc in tl.S. ancl shor,' the inlluence of resuspension rrnd mix- Ceological Survey Open-Filc Repolts (Hemphill ing ol diatom asscmblaliesin the intertidal zone. Halev. 1993a, b). For lhc anal,vses.lhe loi!'est number of lirctors cr- plaining at least 7570 of the lafiance was used. Statstics The sharp break liom rehtivcly high to low factor scorcs \ras used to separate important from cx- The program CABIAC was Lrsedto generatea Q- traneoustilxa comprising each factor. mode factor anahsis (Kloran and Imbric. 1971) to iclentify end-member ppoupsof surface samples Results from three datd scts: (l) transectNl; (2) transcct Nu; and (3) the fbur samplinglocalitics bordering LowerNiawlakum transect (Nl) the open bay. Variables for the {actor analvsiscon- Salinitics ranged flom 100/ooto 27.50/ooat sist of 8,1 ta:

34 Hcm phi11-H.r1.v TransectNl: FactorScores

HIGHMARSH SHALLOWSUBTIDAL LOWMAFSH Faclor 3 Scorss Factor 1 Scoiss (c) (a) (b)::3."*T 2.5 0 Pinn ularia lagerstedtii Actinoptychusspp. Mastogliaexigua Naviculacincta Paraliasubata Cerakulustutgidus (smalllorm) Naviculamutica Nitrschiacdnprcssa psammook Naviculapusilla Nitzschiacoarctata Ni?schianaviculatis gute um einium debilis var paNa Gyrosigna didyna Otuite aspp. Bhopabdiaacuninata NiEshiafascbulata Nitzschiabrevissina GHmnatophua Nitz s hi a scapeIlif o m is &eanica Achnanthesdelbatula C,Moneisscutellun Navbuladigitoradiata Oiploneispseudovalis Synednfasiculata Frustulialinkei NaviculaWgnaea C@oneis placentula Nitzshia cf. nana Naviculattipunctata CHANNELBANK MARSH-UPLAND TRANSIIION Factor 4 ScoFs Factor 5 ScorDs Nitr*hia constticta 3.0 o (e)3.0 o (d) Delphineiscl. Endiclyasp.1 - surrela Frustuliawlgais Adnantheslanceolata Nizschiape ucida Melosiranummuloides Gyr$igma balticun Panlia sulcata Dimercgnmmaninol Naviculalyn Nitrschiapusi a Diplneg interruPta Melasinnonilifomis Caloneiswesti Nitrschiacqnnutata

Figure .1. Factor stores rtlons trannr.t Nl ior autochthonous species (black bars) and susprlLcd allrthrhonous species (whne barsl.

subtil|, NiLzs.:hio plr\ilkr, and Nauicula tenelloidcs. High monh- I'trctor I Eigure 1a1. Autochthonous Nitzschio terrestis was rare but scored high in thc diatoms that can be used to define the high marsh factor analysis because of its limited distribution. inclLtd.e Pinulaia lager;tetltii, liat;icukt pusilkL, and,\lasclr.ia breuisima. Nat:icula cirtcta. Naxic- Nit ztchil commutata. Fnutulia tulgais, CaktneLs uLa mutica, Diploneis pseudoualis, D, rlk\nm, ancl bacillum, Nitzschia cf. nona. and Nitzsr:hiadebiLis tY. de6ift.sarc distributed in high and lorv marshes. ar.c found ;n both low and high marshes. Alloch- Allochthonous diatoms include very rare valves ol thonous diatoms include very rarc valves of Rhaicospheniaabbreuiata anil Achnanthes delicat- Raphoneisd. morgoitaLimbata ^Ld l)imcroglamrrut ukt. NoxicuLtLpypgnnea is also vcry rue. and its sig- minor. n;ficance is uncefiain.

Tntenidal Diatoms from Willapa Bay T.{t]l,l]l.fdclorl.,a.ixjl'.s1ifs!mplingslarn'is!|(ngll!n..ecll\llDth||oiverNia*iakulrRn'e|,Botd{a..nu|t}]ers lactor-. for ralh sarnpling statior.

\ts 0.il8.l 0.0;; 0.92; 0.021 0.t2l 0.0u6 \ll 0.6t9 0.002 0.616 0.1t2 -0.51; 0.11t \t-2 0.;l; 0.l,l(, 0.I8t) .o.o25 -0.832 ,0.029 \|-] 0.529 0.091 0..157 0.2;8 -0.i?2 0._118 \l 1 0.7111 0.155 0.090 0.860 0.0i19 0.086 Nt5 0.;69 0.658 0.019 0.t08 0.291 ,0.18i Nl6 0.Bi,l. 0.919 0.069 0.Iit5 0.081 0.(nl0 Nl-; 0.B01 0.820 0.0,1(, 0.0.10 .o.o2,t -0.3.17 \8 0.!)25 0.278 0.liit 0.0i10 -0.0;6 -0.89i

raien(e 23.Iil6 | 6.96:l r).61 1.1.3:1.1 1U.117 .uhuLLiil, reidrce 2:1.IBa) 40.118 .19.;59 6.1.103 ;7.58

[,orc ntLtsh- Fo,ctor3 (!'igLre,trq. Autochthonous Nu, and rar-evalves of Caloneisa'estii. which las diatoms that identift thc lorv marsh include Gi. lrcquent in the lot' marsh at Toke Point and Sronv rosigrLaeriniunr (common to abundant). \iit.zsclria Point. tlaricukLris. Nitzschia,stnlpeLlifttnnis. and Inr.rru- Shallou subtitlal zone- l'attor 2 (Figure 4b). Lio linkei. Masngloia etigua nar bc primaril,v a By d'finition.cll didlum-irom rhe high. lorv-marsh spccies, brrt it rtas also obser,'ed on the n, rgr rirer channel arc allochthonous (Vos acljaccntchannel bank (Nl 3). It is frcquent in lo*- and de WoU, I9BB). Species that scored high in marsh samples frorn Tokc I'oint. Rluytalodia thc factor analvsis consist of lover-intertidtrl (Gnrrrr oumtirata. Natitula digitorudktLo" .|rld N itzschia epiphyres nuttophortL or'.eorLit:a.CocatneA tnnsticLo are lbund in both lo$ marshts and ad, sur,telLun, C. sculellum \ar. pano. Sq edra epipe- jrcenL flats, anLl\ itzsr:hio..fast iculara and ,\ cl. fasciculatu). lon (Nitzschio contpre-sso. narra are lounrl in low arrd high marshes. A1- i-itzschi,acoarduta, Coc- cone:"rplcrt:entula). or tlchoplanktonic (ie., lochthonousdiatorrs include ver-r rarc valves of diatorns both bcnthic and planktonic Actlnopnclras Ceratau l tu t u rgidus, Rlnp hot Leisp sarnm knkt, and spp.. (small DeLphinei^scl. surirello. P. nrlcria form). and OdontelLa sp1t,).

ClmnneL banh-Foctor 4 lFigure !d). Au- UpperNiawiakum transect (Nu) tochthonous channel-bunli diatoms include Saliniticsranged lrom 2?ooto 23.40lo0 lleLosira nonilifonnis. M. rtunmu,loide;, and Para at tr.ansect Nu, tith a mcan of 14.9{/oo (Figure l3). A IiL nLL:ota: Cyosigrna bahiaun. NoicuLa Lyra. and fir.e- lactor model (Figure 5) iclentified ELdict,\osp. 1 (Hemphill-Halev.1993b) are rare rhe high marsh (Nu-5 to Nu-8; Factor I), lou,-ro-hightransirional but srtrred high in the factor analvsis because ot marsh (\u-,1; !actor 5), lor. marsh (Nu-2, rheif limitcd distriburion. Il. abbret:iatu,anl Ach- Nu-3; Factor 4). channel liank (Ntl; Fa

36 Hemphill-Halev TransectNu: FactorScores

HIGI{MARSH CHANNELBANK SHALLOWSUBTIDAL scorss Fac'toa2 Scoa€s Factot 3 Scores (a) Facto.l (b) (c.l spp. Pinnulaia lagestedtii Diploneissmithii Naviculapusilla Delphineiscl.su rclla var. rnonDrca NiEschiapellucida Endbtyasp.l aphoneiscl.. Rhaphoneispsannicola marganaltnDaa Dentbulasubtilis Syne&afasciculata Rhaphoneisamphicet$ Navbulanutica Melosiramonililotmis Achnantheslanceolata Nizschiacdnnutata Hyalodiscusscotcus Odontelaspp. Gramnatophoe&ean Diploneisdidyna Gytosigmabaltbun Dimerogrannaninor Nitzschiadebilis Centaulustutgidus lnlia sulcata Nitzschiafasciculak Navbulaslesvicensis (smallform) Naviculacincta NitzshiacoarctaE AnphoQ venlicosa Frustuliawlgais Parcliasubak Navbulatenelloides GranmaWhorc oceanca LOWMABSH HIGHio LOW-MARSHTRANSITION Factoa4 Scor9s Factor 5 scoros (d) (e) 2.5 0 3.0 o Gytosigmaexinium Caloneisbacillun Achnantheshauckiana Diploneisinterrupta Hyalodiscuslaevis Anphoacofteitomis mugulus granulata Diploneispseudovalis Naviculaslesvicensis nitzschioides pygmaea Caloneiswesti Navicula Nitzschiaterestris Nitrschiacl. nana Rhqalodiagibberula *utellum exmum uat.paNa pusilla Nitzschiaconstrhta Diploneisdidyna

Fisure5'l.|(totsd,f'sa](lnghanSeclNufo|uu|o('|thonolsspecies61aclrbars)ondsllcrtcdallocb

i\i .incr.r" ,li t:onmultota. ]i. :fa.tciculatu. Diphneis the transcct. Autochthonous diatoms incluclc C'. di$tna and FnLttuLio Lulgaris are distributcd in haciL[urnantl D. pseur1ornls,which were abundant high and low marshes. al Nu-4 but also obscr"rcd in high-marsh samples. D. inkmlpta totaled 3.47o of the assemblage at Lou;to-high LratilionaL marsh lot:tor 5 (Figtre 5el. Sampling station Nu-21is positioned near sampling station Nu-4, but nas less than llo in N{HHV t'here it cxpcr-icnces substantially morc trther rnarsh samples, D. didlzna. li, cl. no.na. ancl tidal submergenccthan thc high rnarsh stationsand \at;icuLa pusilla 'tar. I are distributed in lov and somel{}ratmorc cmcrgencethan stationslo$cr on high marshes. C. eximiunr and Rhopalodia

Interlidal Diatoms liom Willapa Bay 37 T.{I]LE2'I..!clor|oudnlg..fd'SanlI)lings|a1jonsllongtranS{a|t\Uon|lreupper\iarriaLunr ifg lacrorsfor each san,t)lingst!1ion.

Factor '1

\ rr',s 0.9i1 0.032 0.1.1:] -0.97t| -0_tt 0 0.002 \uI 0.888 0_038 0.8?5 0.196 -0.265 0.109 \u-2 0.1171 0.076 o.l2l ,0.201 -0.888 0.I il{r \r 3 0.B01 0.295 0..135 0.090 -0.71,1. 0.087 \u .l 0.92' 0.3t2 0.186 0.01:J 0.138 0.8?B 0.710 0.628 -0.1t5 0.038 0.198 ()_50:l Nu6 0.7,t0 0.i51 ,0.0i0 0.043 0.:322 0.2;5 Nu; 0.768 0.826 0.197 0.090 0.107 0.16? Nr-B 0.1J21 o.492 0.099 0.052 0.061 0.091

29.215 t2.233 I l 58il 17.31i) 12.9,'t6 cunn atire \arian(1 29.215 .11..t.19 53.O3i 70.356 83.302

nrtr.rcalasvere rare in thcsc samples. A1- tidal marshes in thc Copper Rirer delta" Alaska lochthonorrsdirtoms include \erv rarr valves o1 (Hcmphill-Halev. unpub. data). Achnanthe-shaw:l;itLna and Amphoro.utffetLefomis. lrterldalSarpes F rgng r1eOper Bay Lou: nursh-Factor ztrl!'igw 5t11.Autochthonous ,.peciesindicativc of the low mafsh inclucle 6. -saliniq, data lbr nolthern Willapa Bav. collectr:d eritniunr. Nitzs(hia gruruiota. C. r.r,estii.ancl ,\ by the Washington l)epartment of Fisheries cozrli.aal. Allochthonous dialom-qincludc vcrw rare Laboratory at Nahcotta, ind;cate typical rangcs ol valves \rashedin lrorn the adjaccnt muddr bank l0-3001)0,u,ith rxrcasional poiyhalobous ( ) 300/oo) (,\. cornprer.sn.Epithemit turgitlu.. levels. An eight factor rnodcl (l'igure 6) enLificd 'liat:hlneis .toLodisctLs laer,u. arrd aspera . 1'. nitzst:hioides)ot t&'o sandv-ticldl-flatassemblages (BC-1, BC-ii; Fac- high m.ush (1. tenevris l. Prirnarilv empr]- fruslules tor 1: anclBC-2; Factor 7). tu,osilt,v-tidal-flat as- ol C. sulellun and C. scutellurt var. parua ma! scmblages(SP-I to SP-3; Factor i3; and samplcs also be allochthonous. BR-1, BR-2: i'actor 4). a sancll.-tidal-slougha-ssern- blage (TP-l; Factor B), tr,".oTnglorAil lol-marsh Channel bank-Futtor 2 lfigure 5b). A:u- a-ssembiagcs(SlL.l; Factor 6r and'[}'-2. TP-IJ: Fac- lochthonous diatorns inc:l.lrle P. suLcata.C. ocean- tor 2). and a Potentilla, high,marsh asscmblage ica. D. l. surirella. l. coati.th. C. balticurr. (SP-5; Factor 5). Ot Lhc 84 taxa considercdlbr Othor possibll authochthonoLrs.but rerv rarc. di- this studv. 70 r'cre observed in thcsc surr4les. ano attrms incluclc Endictva sp. l, 6'. ntrgi.dus,R. psarn- 68 scored high in thc factor analysis. Thc cight- mi&la. R. arnph.iteros. and Olontella spp. R. lictor rnodel crplaim 810/oof the varinnce, or 90o/o ahbret:iatu anLl A. La,nr:eoktu.arc liket'ise dis- of the data {Table ll). tribLrtedon the channel Lank aiong transect Nl. A1- lochthonousdiatons include verl rare valvcs of Sondl titlu,l Jlat I -Fat:br I (Fig;u,re6a1: lndi<:a- ,\iallctlrz rlesr,icensis.lhich is a high marsh spe- tivc sandilat species include abundant vahcs of C cies rt Stonv Point. scutelLum\ar. pana and ,4. delicatrrla.Other autochthonous specics include Trat:h1splrcnia aus- SfutlLor subtitlal- Facror .3 fFlgare 5c7.All diatoms tral, Cwatosira belgit:a. liadcuLa granuktta, N. lrom the channel arc considered to lie al- cancelklta, a:l) N. c4ptollra. Allochthonous dia- lochthonou-"and inclucle species distlibutcd in torns int:ludc vcrv lare \,al!es ol C. pLacentuLa. lor,rer-interticlal flaIs anelZostera bc.ds. Diploneis yitr. snithi,i rionr6ica scoreclhigh in the f:rctor anai- Sartdt tidal flat 2-Factor 7 (Figure 69l: Sample r'sis because of its lirnitcd dishibulion. No lir.c celLs BC-2 r,".asseparatecl from samples BO-1 and BC-3 were obscned in S illapa Bav samples.but this in the factor analysis because of thc high relatir,e -pe,ie- , omrn,,nlruc.Jf- \1ithL. u..rii in iter- abundancesof the autochthonousspecies '\: h/o.

38 Hcmphill'Halev Op€n.Bay Samples: Facror Scores

SANOY TIDAI FLAT I

35 0 Nilzschia scapellifotm is T?chyspheniaaustahs CYnatosirabelgrca Mastoglia exigua Rhopalodia musculus su/cata(smalllonn) cryplalyra lasbulala gtanulala Navhula Ampho@colfoilomis

Nilzschia fasciculala rutgtca POIEf,'TLI HIGH MARSII Nav i cu I a di9 ilo r a d i al a

cl.nana sp.1 tra Gann4tqhota

odantellaspg,

lagetsle.llii {h) Ftustuliawlgais Navbulact pwa Dinete$ahfia ninol Caloneisbacillun

Cabheisvl€,slii Synedrala*iculata Mebsnanunmulcides Italdiscus scolklrs

knnqtychls sW. O

ligure6. Foctor scores of irtcrnhl surluce sanples collected {rorr the ope. L,a! ior outochrhonous spe.ies ,! blacl, barsl un,l suspected allochthonous spccies l$hile bars).

Tl\BLll 3. Factor L,adings br tnltl llat and marsh samples coller:trd fron northcrn trillapa Bar. Boldface rurnh*s dcnore rlefin ing lactors lor.rch srmt,ling stllion.

cornmuralitr f'!.1,)rl f.r, r 2 fr"to" .t fa, ,,r | 1", r,,,J frrlor rr Fi.tor 7 lr(ttr a

SP.] 0.806 0.0:J'1 0.079 -0.832 0.050 0.0:11 0.030 0.215 0.237 0.;17 0.039 0.l:1.6 -0.56:J -0.153 -0.196 0.505 0.029 -0_300 SP3 o.'1.),' 0.032 0.107 -0.u33 -0.r98 0.1,t3 0.060 0.02; 0.160 st,I 0.862 0.008 0.252 -0-024) 0.l0L 0.195 -0.{165 0.029 0.025 SPar 0.93r 0.008 0.015 -0.03.) 0.01I 0.958 -0.t01 0.026 0.0i.1 BIt 1 0.;75 0.022 0.035 -0.0r)? -0.824 0.061 .0.227 0.r31 0.116 tsH,2 0.?9:l 0.143 0.0B5 -0.06,r -0.862 0.085 0.050 0.002 0.096 BC] 0.52; 0-553 0.022 0.0t7 -0.163 0.0,t4 0.100 0.3,1q 0.2.15 BC2 0.907 o.t23 0.0.1:J -0.t82 0.0!)t) 0.0:J6 0.026 0.919 0.01:l tsc3 0.1196 0.9.11 0.016 -0.028 0.0,1r1 0.011 0.0:1.5 0.007 0.066 11,,t 0.86; 0.0.18 0.291 0.109 0.22{) 0.113 -0.023 0.033 -0.f1.10 t t,-2 0.8r9 0.055 0.888 0.064 0.052 -0.051 -0.0tl O.l2t- -0.01(, 11,-3 0.ll1.1 {).o2..t 0.840 0.060 0.t08 0.078 -0.20!) 0.075 -0.19,1. 9.51 13.02| l3.arl:J t2.24; 8.091 i1.695 n.729 7.78,1 .umulatile rariar(1 9.5| 22.5:tI 36.1;,1- 18.1;9 56.55 65.244 73.373 8l.l5u

Intertidcl DiaLorn.frorn Willapu tsav lJ9 S. fascir:ulota, C. oceanictL.a:r:rl Hvtktdiscus sr:oti- .ottsticta, i\-. tJ. nana, aml tratittt|o t:4ptot.eneLla. cos. ancl the restricted ocr:Ltrrent:eof Atn.phrtrLpnr Rare vah es ol ,\ noriculons, ,\.fasciczlata, ancl tetLs.Cocconei^; diminuta and,\: rrry2lohrc lr.crc F. tt guis are probably also autochthonous. Al- obseNed attachedto sand grains. R. psan.nicoLa lochthonous diatoms ircrludc vcn rarc viilvcs of l). nas originall_vdescribed b_"-Rizn_,-k (1973) from cJ. surireLla. Odontella spp.. M. nunntuLoitLes,M. ticlal flats in Yaquina Bay, Oregon. ,\it;rdtio sigrrzr, nonilifomris, antl P. sulcata, (small folrnl. a cosmopolitan mesohalobous bcnthic diatorn PotentiLla high marsh (Factor 5; Figule 6f: Au- (Hender. 196,1).lr.as Icrv rare at this site. Al- tochthonous diatoms include common cells ol lochthonous diatoms inclucle very rare valves o[ '\i ,\iariczla slesaicensir. \. nLuLit:o.and Stuuloneu an- p|gmaeo ar\d R. tLbbretiato. .e?s, and frequenl ccll,sLtf P. ktgerstedtii. N. rnn- nutkrttt. pellucid,tL. Sil4' ti.datJlat I - lroctor 3 lli3'ure 6cl: Dominant N. and l. c:1.nano.. Ii. r:int:ta. autochthonousspccics include.ll. nonilifonnis, S. N. debiln, and D. pseudotoli.s, also obserr.cd in marsh samplesfrom transctts Nl and Nu. $'ere rare fasr:it ukta. Od,ontella spp.- liitzschia compressa 'I'. lar. rerans. R. psanrmit:ola, ni.tzst:hioiles.Nitz- at this localitr. Allochthonous diatoms indude vcn schia l':)reizi.1na,\i. t'it!)ressaj and Compiodisctts rare valves Lt[ R. ttbbrericr,ttt. echireis.Allochthonous diatoms include verv rare valve-" o[ D. ilLteffuptd. Discussion The clistributionsof intcnidal diatoms in south- Si/4 tidal JIat 2 lactor 4 (Figtre 6d1: Av rvrstern Siashin;1on reflect the tlree-tiered inter- Lochthonousdiatoms'. R. actLntinata.C. or:eonirn. tidal zonation driven h'- differing and C. s(utellun. Rare live cells cf Ttachtneis anounts of tidal submergcncc. similtrr to the distributions of rnarsh utpera and Plagiogrrunnrt stnurophonLm mat lr macrophltes(Macdonald, 1977a, b; lrey and Ba- autochthonous.r'hich is consi-"tenLu,ith tidal-flat san. 1985; Sa1ce.1988) and benthic foraminifcrs distributionsreporled elsewhere(Hendev. 1964; 'fvnni. (Jenningsand Nelson. 1992). Thc 84 tara dis- Riznyk. 1973; l9B3). The highestrelaLive cussed in Lhisreport shot'variable allinities for llercenfages ol P. su,lcu,ta(large ibrm) were ob- cliffcrcnt parts of the intertid:rl and shallow subti- selved in Lhesesarnples. Allochthonous diatoms in dal zone in norlheln Willapa Ba-v(Figurc 7). Many clude verv lare valvcs of I). interntpta- D. dilyna. spocicsarc distributed irr rnore lhan one zonc. Epi.thentia uugitla. l. tenelktides. a:nLlC. placen- whereas others are rnore rcstrictcd. The sampling tzla. possiblvr,".ashcd onto the tid:J flat bv the Bone intcrlal in this studv did not clearlv cliffcrcntiatc Rircr. the boundaries betwren intcrticlalzones, but as Sanch tidaL slouglr-Fador B Figure 6h1: An- shrxn b,vJcnnings nnd Nelson (1992) and Ncl- tochthonousdiatoms include speciesthat favor a son and Kashima (t99il). these bounrlaricsmav sandv substratc lD. minor. N. coatd.lt(r. Anrphor.l be tr':rnsitionalover sevcral tens of ccntimeters. Al, t:entitosu,). are epiphvtic on Zrstera iC. scutel[un- though thc factor analysis separ-aLedshalJor,;- l'1.mtnilfomis)- or are genefally .listribLrledon subtidal iron lorver-intcrticlal-channeloaln sarn- tidal flat,. (,\. con-snicxL.OrbnteLLrL s].t1t.. P. sulutto,l). plcs. the shallol-subtidal samples predominantlv contain allotllhonous tliatoms from lot'er intertidal -l'lctor Triglu hirt1, w marsh I 2 (]'igure 6b): Au- llats anclchannel banks, and thus it could bc ar- tochthonousdiatoms includc comrnon valr.es of,ll gued that lower-intertidal and shallot-subtidal lbssil crigrra. plus Rhopo.Lrxlianusculu: \. stnlpel- assemblagesrrrruld bc indistinguishable.There is lifonnis. \auir:uh phyLle.puL.\. digitorotliota, C. sonc indication that deeper r:hannels()4 m clccp) aestii. :rnd Atrqhorc nlfeaeflnnis. St:olioplcura nrar be distinguishablcfrom shallot' subtida.lchan- tunida. A. t'enLriutstt,and ,\i. conslricrlaare rare ncls in \{ illapa Bav bv higher planktonic dia- bLrtprobablv aLrlochthonous.Allochthonous dialom/bcnth;c diatom ratios (Hemphill-Halev. unpub. tonrs: r'err rare ralvcs ol AmphLtroprotetu anclEn rlrt.rr.hut thi- .",lrrir*-furth-r inrrstigutiun. dictr a sp. l. which rnav harc br-'cnrvashcd in from thc adjacent tidal slough. Ovcrlappirg salinities among the transccls and open brrylocalities allowed frrr similar diatom as 'liiglot:ltinlot+ rnarsh 2-Factor 6 (Figure 6i): Au semblagesin ecologicil zoncsat difierent sites.This tochlhonoLrsspccics inclicativc of the low marshin- agreest'ith published observatiorrsofbrotd salinitr cludc common ccls of C rlestii. C. btLr:ilLun.\. rangcs lor manv brackish species.with dramatic:

,10 Hemphill-Halev i'j !: l: ::li

==+ === i E &: €== i==: ;6: | c)(,)-.1 - : P;I: gsEi€5f x i 6 : * 5: = i . - ...... : aesiE<:o ...... +..".IJ Achnanthesbrcvipes Naviculaphyllepta Achnanthesdelicetula Achnantheshauchata l,lavbulapusi av. 1 Achnantheslanceolata Navbula pygmaea Actinoptychus+p. Navbula slesvbensis Amphon colleaelomis Navbuh tenelloidos Navbula tipunctak Amphoa venlicose Nhzschiabrevissina Caloneisbacillum Nhzschiacommyessa Cahneis westii Nitzschiaconpreisa v. vexans Campydiscus echineis Nhzschiacoatctala Certaulusturgidus Nitzschiacommnala C@coneisdiminuta NiEschia consticta Cocconebplacentula Cocconeisscutellum Nitzschiafasciculata Cocconeissc utel I um v, pava Nitzschiagranubta CytBtosira belgica Nilzschialorenziana Delphineiscl . suirclla Denticula subtilis Nitzschianaviculais Dimercgrammaminor Nitzschiapellucida Dipbneis didyma Diploneisintetrupta Nit zsc h i a scalpe I I ilo rm i s Diploneispseudovalis Nhzschiasigna Endbua sp.1 Nlzschia terestis &ontella+p. Fntstulia vulgatis Gammatophon oceanica P su/cala(smallform) Gyrosigmabalticum Pinnuhie lagerstedtii Gyrosigmaeximium PI ag i og n mma sE uto p hor u i1 Hyalcdiscuslaevis Rha,cneisamphicercs Hyalodiscusscoticus Rhaponeiscl . maryaitalitnbata Mastogloiaexigua Rhaphoneispsammicola Mastolgloia smithii Rhopalodiagibbetula Melosin npnilifomis Bhopalodiamusculus Melosia nummuloides Rlm bo sph e n i a abb rev i ata Naviculacancellata Staurcneisanceps Scoliopleuratumida Navbula cryptotenella Synedrclasciculata Naviculacryptolyn Thalassionemanitzehioides Ilavic u|a digitoad iata Trachyneisespera Neviculagnnulata Trcchyspeniaaustralis Naviculalyra

Figure7'h*'rta|rang(]sli,r8.1dialomspecjesandgr1,Lll)s|ronnorlhtrns]llapaBar''Solitllirl's.do possiblerangeif]n'a|(I]l,lrl]occlnenceS'Al,solutee1e!!Lil[sl;rLhl]in|.j .rl.rlalionsare corsnanrcd br lo,al ti,lol rnDge and ran rith l,xrlti,)trin ar i\(uon.

IntertielalDiatoms liom tr illapa Bay ,11 shifls in diatom populations(triggered bv thc os- cnl inle ;dal zonesand inlluenceshow lell a lbs motic capabilites of various lil\a) occlrfring al sa- sil record is preserved. For cramplc. the linities eithel belor'50/ooor above 30700(Xloorc high-rnarsh diatoms obsen'ed in this studv are and Nlclntirc. 1977: NlcIntire. 197ti; Amspoker dominatcd b,vsmall. solitary. heavil;- silicified spe- and Mchrtire. l97B; Vos and dr Solf. l9tttl; cies that ar.etolerant of largc fluctuations in ten- HemphilJ-Haiey. 1993a). Honevcr, lc,!!rr :rvcragc pcrature. salinil!. and periods ol desiccation salinities at transcct Nu, higher arnounts of liesh imposed by thc highcr clcvationof the marsh cn- $ater run-off from LhePleistocene te ace at Stonv f.ironmenl (e.g., D, sttbtiLis. P. lagerstedtii. N. Point, and geomorphic difli'rcnces beL$eenthe pusilkL). I'or example. thc diurnally submcrgccl lor,,.-marshzones of the open bay and Niat'iakum bank and low marsh along transect Nl experienced Iliver ma,v havc contributcd to some differences a!ela€te 1\'atcr tcmperaturrs that ranged frorn among diatom populationsin this studl-. Muddv 2t).5o(l in Julv 1990 to 5.9oC in Deccmbcr1990. banks of the river and siltt intertidal flats of thc In ()ntrasl, the high marsh i!'as desiccated at air open bav 1r'ercdominatcd by prolific speciessuch temperaturesof 25.5oC ;n Julv 1990 and lrozen as Paralio su/,t:oto.MeLosint monilifomi^s, Sytedra in Decenber 1990, yet ahundant Jivearatoms $'ere litst:icultLta, ar:'d CranLmatophor(LocearLica. The ,,htairredirr -ur[.ree -cmple. on butlr''..r.iuns-ut- opcn bav sand11ats, however. hosted assemblaples tcsting to the resilienceo[ the speciesobserved that were distinctfrom thc mudrJveJripelic assem- there. Manv of thcsc spccicscan bc expectedto blages. Several species that arc commonly ob- ftrssilize well, in contrast to some lor'-marsh clja- sr:rvcd in late Holocene deposits (particularly toms that unclergo tidal submergence at least once Caloneis nestii, ScoLiopleuro tumiiLo. Naticukt per da,v and are more delicatcly silicificd or lire tligitorutliato. ard CanLprLodiscrlsechineis: in gclatinoustubes (e.g., G. exintium. N. scalpel- Hemphill-Hale,v.unpub. data)$crc cithcr rare of lfrrnir (WilJiams. 1965)). abscnt in the steep 1o\! marsh zone along the ri!er, Substrateand sedimcnt grdin sizc are strong but \l,ere iiequent in the gcntly sloping, thickly fontfolling factom in the distribution ofbenthic cs- vegelated, rhgbcAir-dominated lot' marshcs of the tuarine diatorns(e.g., l\{clnLire and N{oore.1977: opcn bal. Sclcr:rl small.slofdr- species (e.€i.. Pin Amspoker and filclntirc. 1978: WhiLing, 19813. nulain kLgerstethii. Nauiar.la puilla. li. mutica. Whiting and l\Iclntire, I9B5: Kosugi, l9B7). lhe Denticula subtilis) appear to be reliable for iden- propensitl for orgflnic carbon to acoumulate in fine Lif,vingthe high marsh, particularly Deschantpsia- or poorly sorted silly sediment. as opposed dominatcd high marshes. €iraincd 'l'he to well-sorted sandv deposits, inllucnccs thc clis- {actor anal-vsisidentified a strbzone at the tribution of intertidal dialoms. In general, diatoms ()n- marsh-upland transition bccausc of the h;gher are more {bundant on silty tidal flats than on sandv (e.g., ccnlratir)nol cerlain species D. subtilru.l. tidal flats (OoJijnand Dijkema. l9BJ ; l.arvs, l9BB) pusilla) in that area. Regarcllesso[ rvhether a par if thev are not dominated by other organisms (Riz ticular lossil assemblagecan be reco€inizcd,thc nyk and Phinne,v. 1972). l hcrcforc, fincl grained marsh-upland transition can br: iclentified bv the piileocstuarincdcposits can be expecled to be more disappcaranceof diatoms in samples deposited diatomaceous than sandv deposits. even cxclud- .trrnJing ahnre EH\\. t nle-. \rr, r i. f,fr-.nl ing thc cffcctsofr,innowing. In addition, diatoms rr'hi,lrT "1,'-ned nnl) onccdrrring rc.unn,ri--.rn,, are t,vpicall,vmore abundant i|'hcrr: ccrtain mar'- slrn'e,vs in variorrs :rreas oi Willapa Ba,v). upland rophvLes are present-either to trap fine-grained surfacesabove the rangc of highesttides border- scdimcntor to ad as substfatefor ep4)hytes-than ing cstuarine marshesin southt'esternWashinEi- rvherethey are absent (llound. l97l; frlain and lon do not support diatom populations,including \lclntirc. 1974; NlcTntircand Moore, 1977). On (see freshrvatcr spccics also Nelson and Kashima. thc channel banks and tidal llats in Willapa Ba,v, I9913).Therelore, the positionofpalco-EHW can epiphvtes iuc prolific on Zrten. especiall, M. bc idcntified bv the transitionliorn peaty diatom- noniliJirmis. M. nrlnLmuLoides,a,i(l S.ftutittLlata. rich marsh deposits to upland peaLsbarren of Howcrcr, these large. delicale speciesleave a poor cllatorns. lbssil rcc,ord. Although solitar,r specieson silty llats The amount of submergenccor dcsiccalional (e.g., Nitzst:hinor:untinttkt, C. cchineis) itrc Lr lcss dilfercnt intcrticlal elevalions is reflected in the prolific than cpiph,vteson Zosteftr. thet- are much phrsiolrgl of the diatom speciesthat inhabit diffcr'- more to likelv to sulvive lbssilizatior,.

42 Hcrnphill-Halc,v 'l'ransport and redeposition of diatorn fiustules llsing the resultsol the factor analvsisas an in co:rstal arcas cannot bc ignorccl in biostrati- cxamplc o{what can be expected in fossil deposits, graphic studies (e.g., Beyens and Den_,-s.l9{:}2; allochthonousdiatoms ale present in mosl samples. Vos and de \{ ol1. l9BB; 1993). ln this stud_v.r.ir with iewer allochthonousvalves in bigh-marsh lually all modern sarnplescontained suspected al- dcposits and morc frcquent allochthonous r.alves lochthonous diatom lalvcs, indicating vhat could in lor.marsh and tidal-flat samples. Thus, because be expectedfor frrssildeposits. Spring high tidcs. of thc occurr-cnccs of allochthonous valvcs, low parLicularlyin associationr,iith sLor-m srrrges, are marshes and tidal llats and banl.is rnav be more capable of topping the highest marshes in Willapa clif{icult to recognize on the basis of diatom assem- Bal and scattcrin;1diatom frustules across upland blages,unless auLochthonous valves are dominant surfaces. During tvpical i{eather conditions. rnanv and/or bcttcr prcscrr;ccl(i.c., shot'cr,idencc for be- scdimcnFassocjatcddiatoms, cspccially such largc ing in siru.). chain-forming ta\a as Me[osira or Paralia lhat <:an- Stdining thc diatom samples used for this stud,v not \rithstnncl strong \rater turbulence. lvill read- provided valuableinsight into the distributionsof ilv bc liftcd into thc plankton. Whiting (1983) moclern estuflrine species (seealso Kosugi, I9B7). likewise noted occurrencesof benthic speciesin Although acid cleaning removcsorganic mdterid plankton samples. that mav obscure the ornamentation on sorne ,'alves.it prohibits Lheidentification of cells that Vith r:ach rising tidc. cpipclic diatoms that fuil *crc livc or rcccntlv dcceaseclat the time of col- to lithdraw below the sediment surface may be lection. Although epilithic or epiph,vticsamples can liftcd up and trlnspoficd up csturry as a sur{dcc "film." be assurnedkr be in sita (c.g.,\Iclntirc and Olcr- Casualobservation shovred that most dia- ton, 1971: S1ainand Xlclntire, I974; Moore and toms in the surface lilm ale small, delicate epipelic Mclntire, I977), scdimcnFassociatcddiatoms (c.g., spccics ,\haicrr.laAalophilo group: Hemphill- found on tidal llats and salt marshes mav or may Haley. 1993b) that arc not tell rcprcsentuJ in fos- noLbe in place. and once a samplc is clcancclit sil deposits. Excluding the eifects of localized is impu-sibletu rliscernr^hether of nol fl -pecic- cliffcrences in sc{l;mcnttcxl(rre causing patchy di- was a living part of the assemblage (e.g.. Riznvk, atom distributions, this regular miring anrl reseetl- 1973; Tynni, 1986). AlLhoughidcntif,ving a livc ing b,v tidcs rcsults in a gcncrally homogcncous cell does not guarantee that it is autochthonous (as (see lorvcr interticlalzonr Riznyk and Phinncv. live cclls of such casily transportcd species ns P. 1972: Rizn,vk. 197i3: Amspokel and Xlclntire, srrlcola ivere commonl,vobsen'ed). recognizing the r97B). cxtcnt of probablc allochthonousinput pror.idesthe kind of inlbrmation necessarv for improving However. althorrgh cliatom cells can be as- paleoecologicalinlerpretations rvhich ultimatclv sumed to be redeposited on a regular basis in anv rnust bc birscd on co-occurrcncesof autochthonous esluarv. observationsof the modern Willapa Ba;- and allochthonous taxa. samplcs indicates that autochthonous benthic spe- far cies t)-pically outnurnber suspeclcd al- Conclusions lochthonous benthic species. Thus. this suggests that in rnostcases (assrrming good preservation)it Diatoms rvcrc collcctcd ;n surfacc sediment sam- should bc possiblc to rcconstluct thc dcpositional ples from tidal llats, intertidal channel banks, shal- environment of a lbssil deposit based on its au- low subtidal channels. and lorv and high rnarshes Lochthonou-qcdrstituents. Sulliran (1975) noted in norlhern W illapa tsay, Washington. Diatom that live allochthonous cells did not suni\.e and liustules were stained in order to identify possible reproducein intertidalhabitats for r,;hichthcy rrerc iillochthonous ta-rain \.a ous ecolopiicsettings. Q- physiologically unsuited. i rther suggesting that mode lactorana]vses identified groups oi intertidal redistributcd dialoms arc unlikcl,vto complctcly samples composed of comparable diatom assem- mask in ritz assemblagesassociated $'ith particu- blages; a.lthoughautochthonous species dominate, lar intertidal settings. Therefore. althorrgh al- someallochthonous species also scorcd high in thc lochthonouscells uill almostcertainlv be present factor analysis indicating thc rcgular influence ol in a sample. it is reasonable to expect that the reworking in the estuary and the pre,'alence of a clepositionalsetting of a ftrssilchposit mar be in- mixcd biocoernosis/thanrtocoenosisin potential Ibs- lerred based on its autochthonouscornponents. sil deposits.

lntcrticlal l)iatoms liom Willapa Ba,v The re-"ultssugge,(t that diatoms can be used Acknowledgments to identiiv thrcc cnrironrnenlal zones relativc to XIark Hemphi11-TIalcr- and Carter Borden ticlalle,'el: (I) tidal llats, channcl banks.ancl shal helped in the lield. Dcnisc Armstlong proricled Lxr, sLrbtidalchannels belon Nll.HS; (2) lo* both laboratory and lield {ssistancc. Kathleerr rnrrshes bctNccn N{LHW and NIHH\\: and (3) Savcc hclpcd rvith the identification o1rnarsh mac- high rn:rrshesbetwccn \'IHHS'and EHW.In some rophytesand provided sulinit,vdata; Janes Say-r:e placcs.un additionalzone mav be lecognizablcon proviclcd clata on tidal rariations in the estuary. thc lrasiso[ :rssemhlagcsthat thri\e near EHS at Flclitorialrer'iews bv John Barron. Alan Nelson. the marsh-uplancllransition. but the position of Richard Laws. und Michael Am-

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Intertidal Diatoms iiom Willapa Bav 45