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Biological Assessment of Kahana Stream, Island of O‘ahu, Hawai‘i: An Application of PABITRA Survey Methods1

J. M. Fitzsimons,2 J. E. Parham,3 L. K. Benson,4 M. G. McRae,2 and R. T. Nishimoto5

Abstract: Aquatic biologists surveyed Kahana Stream on O‘ahu, Hawai‘i, during December 2001 and January, March, and May 2002 to provide a background of information before restoring water diverted from the headwaters of the stream since the mid-1920s. Kahana Stream has all but one species of macrofauna com- mon in unaltered Hawaiian streams, but abundance and distribution of am- phidromous species differ conspicuously. A single specimen of ‘o‘opu ‘alamo‘o (Lentipes concolor) was found near the headwaters; until recently, this species was regarded as extinct on O‘ahu. Only two individuals of the freshwater limpet (hı¯hı¯wai, Neritina granosa) were found, and the brackish-water limpet (hapawai, Neritina vespertina) was not observed. Construction of the Waia¯hole Ditch Tun- nel about 80 yr ago reduced the amount of water entering Kahana headwaters, and unimpeded growth of hau (Hibiscus tiliaceus) from the shore into the stream has slowed water movement in the middle and lower sections of the stream and estuary. Reduced flow has resulted in an extension farther inland of certain es- tuarine and lower-reach species (the prawn Macrobrachium grandimanus and fishes Eleotris sandwicensis and Stenogobius hawaiiensis). Alien fishes and larger in- vertebrates occur throughout Kahana Stream. Catches of newly hatched fish (S. hawaiiensis) and invertebrates (limited to crustaceans) moving downstream to- ward the ocean were meager. Recruitment of animals moving from the sea into the stream included only crustaceans and a single individual fish (S. hawaiiensis). Benthic algae were considerably more diverse than recorded for other O‘ahu streams. Hau removal and extensive trimming at key locations along Kahana Stream should precede the addition of water to the basin to avoid flooding and to enhance beneficial biological effects.

Kahana Stream is 1 This research was supported by a grant from the Di- a prominent feature of vision of Aquatic Resources and Commission on Water the recently renamed Ahupua‘a ‘O Kahana Resource Management, Department of Land and Natural State Park, a designation that appropriately Resources, State of Hawai‘i, for research on Hawaiian emphasizes the fact that the valley is the only stream fishes via the Research Corporation of the Uni- publicly owned ahupua‘a in the state of Ha- versity of Hawai‘i and the U.S. Fish and Wildlife Service Sport Fish Restoration Program, Grant Agreement No. wai‘i. Kahana Stream and Valley are located F-14-R. Manuscript accepted 16 April 2004. on windward O‘ahu about halfway between 2 Museum of Natural Science, Louisiana State the towns of Ka¯ne‘ohe and La¯‘ie. The water- University, Baton Rouge, Louisiana 70803 (e-mail: shed extends from the small village of Kahana fi[email protected], [email protected]). 3 School of Natural Resource Sciences, University near sea level inland to the crest of the of Nebraska, Lincoln, Nebraska 68583-0759 (e-mail: Ko‘olau Mountains at Pu‘u Pauao with an [email protected]). elevation of 814 m. Orographic rain averag- 4 Department of Biology, University of Tampa, ing about 760 cm each year at the back of Tampa, Florida 33606-1490 (e-mail: [email protected]). the valley provides continuous flow in Kahana 5 Division of Aquatic Resources, 76 Aupuni Street, Hilo, Hawai‘i 96720 (e-mail: Robert.T.Nishimoto@ Stream and its tributaries. The flow of water hawaii.gov). is typically clear, cool, and brisk at inland sites but becomes less clear, warmer, and sluggish in the lower and deeper sections close to the Pacific Science (2005), vol. 59, no. 2:273–281 coast. Kahana Stream forms a true estuary in : 2005 by University of Hawai‘i Press its lower reaches where fresh water mixes All rights reserved with salt water before emptying into a partly

273 274 PACIFIC SCIENCE . April 2005

Figure 1. Map of Kahana Valley on the North Shore of O‘ahu, Hawai‘i. protected bay. A drainage channel (Waia¯hole source Management, Hawai‘i Department of Ditch) extends across the back of the valley Land and Natural Resources, in September immediately downslope from Pu‘u Pauao at 2002. the extreme western edge of the watershed to Pu‘u Ka‘aumakua, the peak forming the materials and methods watershed’s southernmost boundary (Figure 1). The ditch captures a substantial amount Survey procedures are adapted from chapter of runoff from orographic rain, and there is 7, ‘‘Methods for Analyzing Stream Ecosys- a plan to release some portion of it back tems’’ by J. M. Fitzsimons, J. E. Parham, and into the Kahana headwaters. In this paper R. T. Nishimoto, in Biodiversity Assessment of we offer certain ‘‘educated guesses’’ about Tropical Island Ecosystems, PABITRA Manual the effect of water return to the basin, but, for Interactive Ecology and Management (D. more importantly, it and particularly the Mueller-Dombois, K. W. Bridges, and C. C. much lengthier report from which it is de- Daehler, eds.) scheduled tentatively for publi- rived provide a baseline for understanding cation in 2005. The book contents are avail- changes in the stream ecosystem after water able at http://www.botany.hawaii.edu/pabitra. volume and flow are increased. This account Stream survey techniques described in the is drawn from ‘‘Biological Assessment of Ka- PABITRA manual have been developed dur- hana Stream, Island of O‘ahu. Final Report’’ ing more than a decade of collaboration by (96 pp.) submitted to the Division of Aquatic the Hawai‘i Division of Aquatic Resources Resources and Commission on Water Re- and the Louisiana State University Museum PABITRA Survey Methods in Kahana Stream, O‘ahu . Fitzsimons et al. 275 of Natural Science. Procedures were devel- was included in the study because of its prox- oped to account for the biological effects imity to the mouth of the stream on the east of the amphidromous life cycles of stream side of the bay and its biological and historical fishes and larger invertebrates and the fre- significance as an integral part of the Ahu- quent flash floods that characterize Hawaiian pua‘a ‘O Kahana. streams. A key element of survey data was the iden- tification of animals associated with discrete results and discussion sections of Kahana Stream and estuary, Hui- Species Complements and Distributions lua Pond, and shore near the stream mouth. Descriptions based on visual observations at A list of fishes and larger invertebrates (Table each study site included the nature of the 1) is provided for the principal study sites in water body (riffle, run, pool, cascade), type of and associated with Kahana Stream. Species shoreline vegetation, extent of the riparian assemblages occurring near the beach, in the zone, bank stability, water appearance, nutri- pond, and in the estuary are likely to vary ent enrichment, barriers to fish movement, according to season, weather conditions, and frequency of pools, extent of canopy cover, movement of marine animals, whether rou- and riffle embeddedness. Characterizations tinely or fortuitously, into and out of waters of these features are regarded simply as refer- of lowered salinity. The species occurring ence conditions because most are determined farther inland at the middle and upper sec- largely by the time elapsed since the most tions of the stream are much less likely to recent flash flood. In this context, it should vary. Although the young of these upstream be stressed that Hawaiian streams are not animals are migratory (Nishimoto and Kua- stable; they are dynamic. Biological data en- mo‘o 1997), adults predictably occupy cer- compassed species distributions, density and tain sections of a stream (Fitzsimons and relative abundance (via random and nonran- Nishimoto 1991). Individual fishes of certain dom underwater transect and point-plot sur- species inhabit discrete territories used in veys, trapping, netting, and take by hook- feeding and spawning for several months and-line), downstream drift toward the sea (Fitzsimons and Nishimoto 1995) or even of newly hatched larvae and free-swimming for years (Nishimoto and Fitzsimons 1986). embryos (sensu Balon 1990), recruitment of Kahana Stream has nearly a full comple- larvae and juveniles migrating into fresh ment of indigenous aquatic species, but the water from the ocean, behavior associated distribution and relative abundance of these with feeding and habitat selection by imma- animals differ from their occurrence in simi- tures and adults, evidence of reproduction, lar unaltered streams on windward coasts time budgets, species-specific behavior, para- of the outer islands (stream survey database, sites in indigenous and alien fishes, and types Division of Aquatic Resources). Four species of benthic algae. The biological data were usually common in the middle and upper sec- linked to a Geographic Information System tions of Hawaiian streams (i.e., the gobies (GIS) program for mapping, identifying spe- Awaous guamensis [‘o‘opu na¯kea], Sicyopterus cies’ microhabitat preferences, and assimilat- stimpsoni [‘o‘opu no¯pili], and Lentipes concolor ing physical and biological information. [‘o‘opu alamo‘o], and the mountain shrimp Study sites were selected in the lower, Atyoida bisulcata [‘o¯pae kuahiwi]) were sparse middle, and upper sections of Kahana Stream in Kahana Stream even though suitable according to basin morphology and the distri- habitats for each species were available. The bution of indigenous animals. Sampling sta- sighting of a single individual of ‘o‘opu ala- tions in the lowermost stream reach included mo‘o (Lentipes concolor) in its characteristic the seven sites used by Timbol (1972) in a habitat in upper Kahana is important because study of the trophic ecology and macro- until recently this species was considered fauna of Kahana estuary. Although not actu- extinct on O‘ahu (Higashi and Yamamoto ally part of Kahana Stream, Huilua Fishpond 1993). Conversely, the prawn Macrobrachium TABLE 1 Aquatic Macrofauna Observed or Collected in or near Kahana Stream during December 2001 and January, March, and May 2002

Shallow water near beach Psilogobius mainlandi, Hawaiian shrimp goby Atherinomorus insularum, ‘iao, iau, Hawaiian Islands Sarotherodon melanotheron, blackchin tilapia silverside (introduced) Synodus ulae, ‘ulae, red lizardfish Scylla serrata, Samoan crab (introduced) Tylosurus crocodilus, ‘aha, hound needlefish Synodus ulae, ‘ulae, red lizardfish Huilua Pond Valamugil engeli, Marquesan mullet, Australian mullet, Abudefduf abdominalis, maomao, mamo, green kanda (introduced) damselfish, sergeant major Mid-Estuary (above bridge) Abudefduf sordidus, ku¯pı¯pı¯,‘o¯‘o¯ nui, blackspot sergeant Caranx spp. (2), jack crevally family Acanthurus triostegus, manini, convict surgeonfish Eleotris sandwicensis, ‘o‘opu ‘akupa Ariosoma marginatus, puhi u¯ha¯, tohi, large-eye conger Kuhlia xenura, a¯holehole, Hawaiian flagtail Bothus mancus, pa¯ki‘i, ‘ui‘ui, flowery flounder Lutjanus fulvus, to‘au, flametail snapper (introduced) Carangoides ferdau, ulua, barred jack, blue trevally Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Diodon hystrix, ko¯kala, spot-fin porcupinefish Palaemon debilis, ‘o¯pae huna, shirasa Kuhlia xenura, a¯holehole, Hawaiian flagtail Scylla serrata, Samoan crab (introduced) Neomyxus leuciscus, uouoa, acute-jawed mullet, Synodus ulae, ‘ulae, red lizardfish sharpnose mullet Upper Estuary (to inland limit of boat traffic) Portunus sanguinolentus, ku¯honu, haole crab, blood- Eleotris sandwicensis, ‘o‘opu ‘akupa spotted crab Kuhlia xenura, a¯holehole, Hawaiian flagtail Synodus ulae, ‘ulae, red lizardfish Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Mouth of Kahana Stream Macrobrachium lar, Tahitian prawn (introduced) Alpheus sp., snapping shrimp Poecilia mexicana/sphenops, shortfin molly Kuhlia xenura, a¯holehole, Hawaiian flagtail (introduced) Lutjanus fulvus, to‘au, flametail snapper (introduced) Poecilia reticulata, guppy Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Scylla serrata, Samoan crab (introduced) Mugil cephalus, ‘ama‘ama, striped mullet Xiphophorus helleri, green swordtail (introduced) Mulloides flavolineatus, weke, yellowstripe goatfish Middle section of Kahana Stream (U.S.G.S. Gauging Palaemon debilis, ‘o¯pae huna, shirasa Station at 10 m elevation) Portunus sanguinolentus, ku¯honu, haole crab, blood- Kuhlia xenura, a¯holehole, Hawaiian flagtail spotted crab Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Psilogobius mainlandi, Hawaiian shrimp goby Macrobrachium lar, Tahitian prawn (introduced) Scylla serrata, Samoan crab (introduced) Stenogobius hawaiiensis, ‘o‘opu naniha Sphyraena barracuda, ka¯ku¯, great barracuda Xiphophorus helleri, green swordtail (introduced) Synodus ulae, ‘ulae, red lizardfish Middle section of Kahana Stream (bamboo grove at Valamugil engeli, Marquesan mullet, Australian mullet, 45 m elevation) kanda (introduced) Awaous guamensis, ‘o‘opu na¯kea Lower Kahana Estuary (to Kamehameha Highway Kuhlia xenura, a¯holehole, Hawaiian flagtail bridge) Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Acanthurus xanthopterus, pualu, yellowfin surgeonfish Macrobrachium lar, Tahitian prawn (introduced) Alpheus sp., snapping shrimp Sicyopterus stimpsoni, ‘o‘opu no¯pili Caranx sp., jack crevally family Xiphophorus helleri, green swordtail (introduced) Eleotris sandwicensis, ‘o‘opu ‘akupa Upper Kahana Stream (140 m elevation) Grapsus tenuicrustatus, ‘a‘ama crab Kuhlia xenura, a¯holehole, Hawaiian flagtail Kuhlia xenura, a¯holehole, Hawaiian flagtail Macrobrachium lar, Tahitian prawn (introduced) Lutjanus fulvus, to‘au, flametail snapper (introduced) Upper Kahana Stream (at north terminus of the Macrobrachium grandimanus, ‘o¯pae ‘oeha‘a Waia¯hole Ditch Tunnel) Mugil cephalus, ‘ama‘ama, striped mullet Atyoida bisulcata, ‘o¯pae kuahiwi Palaemon debilis, ‘o¯pae huna, shirasa Lentipes concolor, ‘o‘opu ‘alamo‘o, hi‘ukole Poecilia mexicana/sphenops, shortfin molly (introduced) Macrobrachium lar, Tahitian prawn (introduced) Portunus sanguinolentus, ku¯honu, haole crab, blood- Sicyopterus stimpsoni, ‘o‘opu no¯pili spotted crab PABITRA Survey Methods in Kahana Stream, O‘ahu . Fitzsimons et al. 277 grandimanus (‘o¯pae ‘oeha‘a), a species typical December 2001 and March 2002 provided of the lower reaches of streams, had a range the opportunity to obtain information on an- extending farther upstream and was more imal distributions and water chemistry data in numerous in Kahana Stream than in compa- the estuary and stream during periods of both rable habitats of other streams. Decades of low and high water. At all sites in the estuary, decreased flow in Kahana Stream via water the pronounced disparity in surface versus diversion and the damming effect of hau (Hi- bottom conductivity during low stream flow biscus tiliaceus) have extended estuarine and in December indicated a well-developed lower-reach habitats farther inland, and the wedge of salt water extending throughout species adapted to these conditions have the estuary from the mouth to the upstream occupied them. The streamwide range of limit of boat traffic (1.6 km). In contrast, Kuhlia xenura, an endemic marine fish whose conductivity measurements at the water sur- young (a¯holehole) commonly enter fresh- face and bottom during March indicated that water streams in Hawai‘i, was exceeded only intruding salt water had been pushed sea- by that of the introduced Macrobrachium lar ward by stronger stream flow. A concomitant (Tahitian prawn), which occurs from the up- change in the kinds and numbers of animals per estuary to the upper section of Kahana present at different sites in the estuary oc- Stream. Although a¯holehole are ubiquitous curred during the two periods of sampling. in island streams, these fish do not have a For the indigenous estuarine prawn Macro- physiological requirement for fresh water at brachium grandimanus, catch per unit effort a specific point in their life cycle (Benson was nine times greater in traps during March and Fitzsimons 2002); however, the overall (979 hr of sampling) than in December (1,484 importance of streams as nurseries and refu- hr). ‘O‘opu ‘akupa, the eleotrid that occurs in gia for a¯holehole has not been determined. It lower stream reaches in Hawai‘i, was absent is not known whether the introduced prawn in collections in the estuary during December competes with the native congener M. grandi- but well represented in March. Conversely, manus or feeds on the eggs, young, or adults higher-salinity species (i.e., introduced Sa- of naturally occurring stream animals. Neri- moan crabs and to‘au) were about 10 times tina granosa (hı¯hı¯wai or wı¯) was represented less frequent during the higher flow period. in all surveys by only two individuals ob- For all fish and invertebrate species com- served in the middle section of Kahana bined, catch per unit effort in traps was Stream; these limpets are common in the much greater during the period with high dis- fast-flowing sections of many undiverted Ha- charge (March) than during low discharge waiian streams. The brackish-water limpets (December). This observed in-stream move- Neritina vespertina (hapawai) frequently are ment of animals in response to salinity dif- found on hard surfaces (rocks, boulders, ferences in the Kahana estuary may also be bridge supports) in estuaries of streams, but expected when additional water is added to none was observed in Kahana Stream. the headwaters. In Huilua Pond, all species of animals ob- Most biological information and water served or collected were endemic (i.e., they chemistry data (pH, temperature, salinity, occur naturally in Hawaiian waters). From conductivity, and salinity) obtained through- the mouth of the stream to the upper part out the length of the Kahana estuary in the of the estuary roughly one-fourth (23–25%) current study are remarkably similar to the of the species were introduced. In the middle data recorded by Maciolek (1972) and Tim- section of Kahana Stream and at one site in bol (1972) over 30 yr ago, but there is one the upper section, alien species composed striking exception. At their recording stations, 30–50% of the faunal assemblage. Even at which we also used, surface and bottom the headwaters, one out of four aquatic spe- dissolved oxygen concentrations were always cies was a nonnative. very near, at, and sometimes above 100% sat- Markedly different weather conditions uration. In our work, all readings (surface and (rain and resulting stream discharge) during bottom at seven sites) were well below satura- 278 PACIFIC SCIENCE . April 2005 tion. We suggest that this disparity is directly cycles. However, the relatively high preva- attributable to heavy siltation, decaying veg- lence of the trematode Opecoeloides kuhliae in etation, retarded primary productivity, de- K. xenura from the estuary may provide a creased aeration effects from flowing water, model for analyzing parasite dynamics in the and other factors that reduce dissolved oxy- estuary in connection with changes in pat- gen because overgrowth of hau (Hibiscus tilia- terns of flow that would occur if water volume ceus) along stream banks is hindering the in Kahana Stream were augmented. flushing action of strong flow and periodic freshets (flash floods). Algae Twenty-six species of macroalgae were iden- Animal Migrations tified by A. R. Sherwood (University of Ha- Drift and recruitment collections reflect, wai‘i) from five collecting sites in the middle respectively, the downstream movement of and upper sections of Kahana Stream. This free-swimming embryos and larvae of fishes taxonomic richness is greater than that cur- and invertebrates and the upstream move- rently noted for other streams on windward ment of animals leaving the ocean and return- O‘ahu and exceeds the averages for streams ing to fresh water. Drift indicates a certain on the North American mainland and Carib- stream’s potential contribution to the popu- bean Islands. lation of plankton offshore that will be avail- able for future recruitment to one or more The Problem with Hau: An Evaluation and streams. In Kahana Stream, drift was limited Recommendation to crustaceans and two species of fishes, Sten- ogobius hawaiiensis (‘o‘opu naniha) and Eleotris Whether labeled indigenous (native), alien, sandwicensis (‘o‘opu a¯kupa). Trapping of ani- or a ‘‘naturalized Polynesian introduction’’ mals recruiting into the stream mouth yielded (Sohmer and Gustafson 1987), hau (Hibiscus only crustaceans and a single individual of S. tiliaceus) is biologically both beneficial and hawaiiensis. detrimental for Kahana Stream. Intertwined roots and limbs extending into the water sometimes produce a nearly impenetrable Parasitology tangle that provides cover against predators Fourteen species of parasites were found by for K. xenura at the mouth of the stream W. F. Font (Southeastern Louisiana Uni- and for the native prawn M. grandimanus versity) in 17 species of fishes in Kahana throughout the estuary. However, unchecked Stream and estuary. The roundworm Camal- growth of hau has choked down the navigable lanus cotti, tapeworm Bothriocephalus acheilog- waterway in the upper estuary and prevented nathi, and leech Myzobdella lugubris were the freshets from flushing silt and debris from only parasites sufficiently abundant to cause critical habitats for aquatic animals in the disease in native fishes. All three parasites middle and lower sections of Kahana Stream. were introduced into Hawaiian waters along During flash floods, even relatively small with alien fish species, mostly live-bearers in ones, the damming effect of hau often causes the family Poeciliidae (represented in Kahana localized flooding in the lower part of the val- Stream by mollies, guppies, and swordtails). ley. In the middle part of the valley during 4 The occurrence of heavy infections of C. cotti and 6 May 2002, heavy rainfall produced a in Kuhlia xenura is disconcerting because flash flood that washed out stream banks and these euryhaline fish, unlike the gobies lim- knocked down hau trees, some with trunks ited as adults to fresh water, have the po- up to a half meter in diameter. Hau trunks, tential for spreading the parasite to other roots, and branches, along with other debris, streams. Camallanus cotti and B. acheilognathi formed a temporary dam that shunted large do not tolerate the higher salinity in the estu- quantities of water into an ancient ‘auwai ary during the free-living stages of their life (water-diversion channel used for traditional PABITRA Survey Methods in Kahana Stream, O‘ahu . Fitzsimons et al. 279 taro agriculture) that flows near the U.S. Geo- cycles; in addition, the migrants are more dis- logical Survey gauging station (no. 16296500 persed and less easily taken by predators. Pre- at 10 m elevation) on the stream. The ‘auwai liminary studies by the late R. J. F. Smith was severely damaged, and residents ex- (University of Saskatchewan) indicate that pressed concern about the effect of the flood freshets may be important also by sending on their livelihood, personal safety, and the into the ocean an olfactory or gustatory stim- potential loss of important archaeological ulus that causes larval stream animals to com- sites. Residents identified the source of the mence movement inshore and upstream. A problem to be the dense growth of hau. Resi- hypothesis based on experiments in artificial dents whose families have lived in Kahana streams (Fitzsimons et al. 1997) suggests that Valley for many generations believe that stronger flow and flash floods may help overgrowth of hau was not a problem before eliminate or at least reduce numbers of alien the stream was diverted in the early 1900s. fishes that compete with natives for resources However, it is unknown whether Hawaiians and serve as a source of parasites known to managed the stream to keep it open or have deleterious effects on indigenous species whether the greater flow and concomitant (Font 1997, 1998). In Kahana Stream, addi- stronger flash floods provided a natural con- tional water and more effective flash floods trol. may redistribute stream animals in patterns Complete removal of hau from the banks that more closely resemble those observed in of Kahana Stream would be neither beneficial comparable unaltered streams. The argument nor practical. Instead, a program of cutting here is that the species-specific patterns of back and removing hau at selected sites could distribution commonly seen in undisturbed improve stream flow, leave critical cover for streams indicate the results of thousands of aquatic animals, protect the stream banks years of gradually evolved adaptations for liv- from erosion, safeguard archaeological sites, ing in Hawaiian streams. Restoring these pat- and enhance water use for people living in terns in Kahana Stream presumably would be the valley. The initial task would be substan- beneficial for replenishing aquatic species and tial, and, for the work to be successful, the for maintaining the intrinsic organization of preliminary effort would need to be followed aquatic communities. by continued trimming. Given the current Ideally, controlling hau and returning conditions of hau overgrowth in Kahana water to Kahana Stream would clean the Stream, the addition of water to the basin stream bottom, halt blooms of filamentous would exacerbate problems with flooding. algae, facilitate movements of migrating ani- Judicious trimming and removal of hau mals, send signals that guide young amphi- likely will assist in realizing the potential bio- dromous animals as they repopulate the logical benefits hoped for by increasing the stream, reduce the numbers of alien species, volume of water entering the headwaters of and restore the natural distribution of indi- Kahana Stream. A brisk, continuous flow and genous stream and estuarine animals. Real- occasional flash floods provide several advan- istically, the effects are likely to be less tages for Hawaiian stream animals (Fitzsi- definitive. A graded response is more proba- mons et al. 1996). Silt, leaf litter, sticks, and ble. Kahana Stream has a well-developed, other debris are swept from places where natural estuary that will continue to slow aquatic animals live and deposit their eggs. water movement. There is a possibility, too, Blooms of filamentous algae that cannot be that the amount of water available for place- used as cover or food by stream animals are ment back into Kahana Stream may be insuf- curtailed by the abrasive action of waterborne ficient to bring about susbstantial changes. If sand and gravel. As stream mouths are wid- discharge is increased at the mouth of Kahana ened and deepened by freshets, easier access Stream, natural restocking of fishes and inver- is provided for young animals swimming into tebrates may continue to be low if only small and out of the stream mouth during the numbers of potential recruits exist within Ka- migratory stages of their amphidromous life hana Bay or in the surrounding ocean waters. 280 PACIFIC SCIENCE . April 2005

If this occurs, stocking of adult animals may by W. Devick (Aquatic Resources), L. Nish- be necessary. The return of any water to the ioka, E. Sakoda, E. Hirano, D. Nakano, and stream that enhances natural flow patterns D. Higa (Water Resource Management), D. should be a positive step toward stream resto- Quinn, A. Rogers, M. Yent, T. Palermo, and ration. The added water would provide addi- Kahana staff (Division of State Parks), N. Yen tional adult habitats and improved migratory (Division of Conservation and Resource En- pathways. Even if no additional water is placed forcement), and A. Lee, L. Owan, and G. An- into Kahana Stream, the control of hau to guay (Hawai‘i Agribusiness Corp.). We are eliminate damming during freshets should in- especially indebted to U. Beirne, S. Greer, B. crease the connectivity of the stream, estuary, Shafer, K. Gorai, V. Soga, B. Soga, and other and ocean waters to the benefit of native am- residents of Ahupua‘a ‘O Kahana for welcom- phidromous animals. Additional benefits may ing us into their valley home. We are grateful also result in terms of decreased flood damage also to K. Faris and S. Kubota for sharing to personal property and archaeological sites. their expert knowledge on matters both philo- sophical and practical in respect to Hawaiian streams and their conservation. Extension of PABITRA to Other Islands Although a number of biological survey pro- Literature Cited cedures exist for continental streams, PABI- TRA methods, although drawing from many Balon, E. K. 1990. Epigenesis of an epigene- of these, were intentionally designed and field ticist: The development of some alterna- tested for use in island streams. The format is tive concepts on the early ontogeny and intended to be flexible and capable of accom- evolution of fishes. Guelph Ichthyol. Rev. modating new sources of information while 1:1–42. excluding those that are irrelevant or difficult Benson, L. K., and J. M. Fitzsimons. 2002. to use because of local conditions. Indigenous Life history of the Hawaiian fish Kuhlia animals (fishes, mollusks, and crustaceans) in sandvicensis as inferred from daily growth Hawaiian streams have relatives throughout rings of otoliths. Environ. Biol. Fishes Oceania that are strikingly similar in their 65:131–137. life histories, habitat selection, behavior, and Fitzsimons, J. M., and R. T. Nishimoto. ecology (Fitzsimons et al. 1996, 2002). For 1991. Behavior of gobioid fishes from these reasons, we suggest that the PABITRA Hawaiian fresh waters. Pages 106–124 in stream methods, or something like them, are W. S. Devick, ed. New directions in re- applicable among most oceanic islands of the search, management, and conservation of tropical Pacific and beyond. Hawaiian freshwater stream ecosystems: Proceedings of the 1990 Symposium on acknowledgments Stream Biology and Fisheries Manage- ment, State of Hawai‘i, Department of This paper is based on a collaborative field Aquatic Resources, Honolulu. effort involving personnel from the Hawai‘i ———. 1995. Use of fish behavior in assess- Division of Aquatic Resources (G. Higashi, ing the effects of hurricane Iniki on the D. Kuamo‘o, and R. Nishimoto), the Com- Hawaiian island of Kaua‘i. Environ. Biol. mission on Water Resource Management Fishes 43:39–50. (D. Uyeno), Louisiana State University (L. Fitzsimons, J. M., R. T. Nishimoto, and Benson, J. Coleman, M. Fitzsimons, M. W. S. Devick. 1996. Maintaining biodiver- McRae, C. Murphy, and A. Styring), Univer- sity in freshwater ecosystems on oceanic sity of Nebraska ( J. Parham and M. Steina- islands of the tropical Pacific. Chin. Bio- uer), University of Southeastern Louisiana diversity 4 (supplement): 23–27. (M. Collins, W. Font, A. Vincent, and J. Wil- Fitzsimons, J. M., H. L. Schoenfuss, and lis), and the University of Hawai‘i (A. Sher- T. C. Schoenfuss. 1997. Significance of wood). Support in myriad ways was provided unimpeded flows in limiting the transmis- PABITRA Survey Methods in Kahana Stream, O‘ahu . Fitzsimons et al. 281

sion of parasites from exotics to Hawaiian sources, State of Hawai‘i, Honolulu. stream fishes. Micronesica 30:117–125. (Available from Division of State Parks.) Fitzsimons, J. M., J. E. Parham, and R. T. Nishimoto, R. T., and J. M. Fitzsimons. Nishimoto. 2002. Similarities in behavioral 1986. Courtship, territoriality, and color- ecology among amphidromous and cata- ation in the endemic Hawaiian fresh- dromous fishes on the oceanic islands of water goby, Lentipes concolor. Pages 811– Hawai‘i and Guam. Environ. Biol. Fishes. 817 in T. Uyeno, R. Arai, T. Taniuchi, 65:123–129. and K. Matsuura, eds. Indo-Pacific fish Font, W. F. 1997. Improbable colonists: Hel- biology. Ichthyological Society of Japan, minth parasites of freshwater fishes on an Tokyo. oceanic island. Micronesica 30:105–115. Nishimoto, R. T., and D. G. K. Kuamo‘o. ———. 1998. Parasites in paradise: Patterns 1997. Recruitment of goby postlarvae into of helminth distribution in Hawaiian Hakalau Stream, Hawai‘i Island. Microne- stream fishes. J. Helminthol. 72:307–311. sica 30:41–49. Higashi, G. R., and M. N. Yamamoto. 1993. Sohmer, S. H., and R. Gustafson. 1987. Rediscovery of ‘‘extinct’’ Lentipes concolor Plants and flowers of Hawai‘i. University (Pisces: Gobiidae) on the island of O‘ahu, of Hawai‘i Press, Honolulu. Hawai‘i. Pac. Sci. 47:115–117. Timbol, A. S. 1972. Trophic ecology and Maciolek, J. A. 1972. Diadromous macro- macrofauna of Kahana Estuary, O‘ahu. fauna and the Kahana Stream-Estuary eco- Ph.D. diss., University of Hawai‘i at system. Report to Division of State Parks, Ma¯noa, Honolulu. Department of Land and Natural Re-