HAWAI'I'S WETLANDS, STREAMS, FISHPONDS, AND POOLS Wetlands, streams, and anc!,ialinepooLF are among the most threatened o llawaiian envrronments.hecauy they are located where conflicts wit f I other human needs ore rncremng drumalically.

Charles P. Stone

The Hawaiian Islands have a number of increasingly rare plant and ani- mal communities that deserve suecial consideration. Amone these are various cave and grassland communities and some important arem &at will be consid- ered here-those dependent upon fresh water or a mixt~lrc of fresh and sc ;~ water. Wetlands. the transition zones between terrestrial and aauatic NO- systems, we cha~actzristica~l~ saturated with or covered hy watc;, at Icmt periodically, and soil development and 11lant and animal communities :ire delermined hv water ICowurdin rt ul. 1979). Natural wetland habitats include marshes. swa;nps, and hO&v (the last of which are discussed hy Cuddihy, this volume). Anthropogenic (man-made) wetlands include u r o pmhes, prawn ponds, some fiihponds, and other irrigated croplands.

Deeuwdter habitats for plants and animals lie beyond the boundaries of wetlands'in the form of lakes, estuaries, the ocean, streams, man-made reservoirs, and some fishponds and pools. Tn these areas, water rather than air is the main medium in which dominant organisms live. Reservoirs in Hawai'i are primarily used for irrigation rather than for municipal water. The few natural lakes are distinguished from ponds by surface area and depth Maciolek 1982). Lake Wai'au on Mauna Kea (island of Hawai'i), at 13,020 ft 3,970 m), is considered the second-highest freshwater lake in the United

States. It is an &im lake (above most vegetation in elevation; see Cuddihy, this volume) resting in the center of a cinder cone, about 40 acres (16 ha) in size, and reachin a maximum depth of 10 ft (3 m) (Cruikshank 1986). Lake Wai'ele'ele, at 6, 00 ft 2,000 m) on the slopes of Haleakala on Maui, is an example of a

t3 n [mountain) lake, with a maximum depth of 21 ft (6 m).

In Hawai'i, l a m o t often develop because substrates of basalt are ex- tremely permeable and rain water ts quickly lost to the groundwater table. Evapotranspiration is also high in some areas with low to moderate rainfall. Upper-elevation lakes are species-poor but of value because of the~r rarity and uniqueness. Lower-elevation lakes and reservoirs receive use by waterbirds.

Many streams in Hawai'i are interrupted (flowlng on1 part of the year) because of steep stream gradients, shortness of streambed, seasonal, rainfall, and the permeability of soil and rock. Hawaiian streams are also qulte vari- able in volume of flow. Plants and animals living in streams must often be adapted to extreme variations in temperature, turbidity (cloudiness), and amount of aquatic habitat available at different times. Consistent stream

flow is most likely in mountain areas with more regular orographic rainfall (Armstrong 1983).

Anchisline ~ o o l s are small bodies of water located near the ocean. Thev have no surfasec~mnect~on 11, the sea hut have measurable salinity (salt

'

content) and rhow tidal rhythms. They are found in the Tropics and sub- trupical areas and support a unlque but ooorly underctood biota. Hawai'i's anihidine no01 corndlixes have i ereatei~ercentaee of endemic snecies and perhap\ the highe\t biological div&sity of'any ~ u c h ~ ~ o o l s in the w&ld (Maciolek 19x6). They, ltke many of the special llawaiian areas which will he discussed in this essay;are especially at risk because of intensive human use of the coastal and lowland areas in which they occur.

WETLANDS

A maior reason for concern about wetland areas in Hawai'i todav is their importanfe for native waterb~rds. The most important areas are lowland freshwater marshes and associated deepwater areas (ponds, laker, and reser- voirs): cultivated wetlands: and shallow mareins of some anchialine oools. Marine-dependent wetlands such as mnngrok communities (first inirodl~ced in 1002 to Moloka'i) and estuaries will not be discussed in this essay, al- thou~h they are also usea bvwaterhirds. (See Sternmermann 1981 fur a discu<sion bf eight natural and anthropogenic wetland vegetation types on Pacific islands.)

Polvnesian Aauaculture "~ol~nes ian 'eoples eqtablished a well-managed environment in Hawai'i's

lowI:tnd.. incluRns "slash and, burn ag r~cuh re and arcas in which water was controlled for D ant and animal cultivatir)n. The oeak of Polv- nesian agricultural develbpment robably coincided with hiihest hum& popu- lations, which occurred about 1690 AD.; human numbers then declined until Euro ean contact (Kirch 1982). Clearing of large areas of forest below b' 2,000 ft (6 0 m) elevation ne atively affected the original lowland biota but allowed dense po ulations ofhumans to exist (see also Burrows, this volume). Forests above suc \ areas as Kawainui Marsh and Kahana Bay on O'ahu, Hanalei Valley on Kaua'i, and Waipi'o Valle on Hawai'i Island may have been removed artly to encourage erosion o?upland soils into lowland wet- land areas use c r for taro (Colocmia esculenta) cultivation. (See Spriggs 1985 for a full discussion of rehistoric landscape modification.) Acreages of fishponds and irrigatezfields at lower elevations were much greater in pre- contact days than at any time since and undoubtedly favored some native species of plants and animals.

Fishwonds: Over 350 fishponds ofvarious kinds havc been identified on the eight maor Islands. Although some provided only cleepvater habitat for A birds, ot ers were true wetimds. Stationary sluice gates were the tcch- nological invention which probahly allowed Howaiinns to convert fish traps (with o enings to the sea) to artificihl fishlmnd, ~ndqendcnt of tidal fluctu- ations &~ple and Kikachi 1977). Smaller s u e t c s e d in irrigated taro fielas (lo'!) to control water flou mav have heen t e orlelli of ii\hoond sates. ~ishpondswere apparently not devdoped by other pre-:ontact cdturesof the

Pacific but were used especially from the 14th to 19th centuries in Hawai'i (Kikuchi 1976).

Two major kinds of Hawaiian fishponds were recognized by Summers (1964): 1) Shore ~ o n d s or salt water ~ o n d s included loko kuapa and loko 'umeiki. Kuapa were made either by extending a semicircular wall from the shore into the sea and hack to shore, or by walling off the narrowest part of an entrance to a small hay or inlet. Most of the Moloka'i fishponds were built this way. Loko 'umeiki were "surrounded by a low wall that is submerged at high tide and has openings walled on each side like lanes, leading in or out of the pond" (Summers 1964). These served as fish traps but were regarded as ponds by the Hawaiians. 2) lnland pncLs or brackish and fresh water ~ o n d s were divided into three categories, lokopu'uone (not fresh water) and loko i'a kalo and loko wai (fresh water). Loko pu'uone were usually connected to the sea by a ditch or stream. Loko i'a kalo were the "taro fish ponds," and loko wai were natural ponds.

Pond sizes raneed from 0.5 to over 500 acres (0.2-200 ha). accordine to Cohh (1002). and the I q c , t pond. w r e uw~l lv 1;ko ku3pa.'Fishes raiied in I ~ k o kuap:~ included ' ~ I I Z J ~ I Z , ~ or mullet (.\l~~,qrl (c~pl~nlus). awa or milkfish (Cltanosci~ano), awa'aua (Elops macllnata), al~olei~ole (Kuhlia sandvicensis), and 'o'oou (rabies). The loko 'umeiki also had 'ama'ama and awa but con- , ", &ncd a number (if oce:~n h h e s thxt rntrreJ the ponds hut were not raised in them. 1;ishes raised in loko pu'u(~ne i11iluJr.J 'dma'ma, awa, aholehole, and 'n'oou. while loko i'a kilo cc)n t~ ind 'nm~'dm3. awa. 'o'oou. aholehole. . . and 'op;e (hhrirnp). l ako wai held 'o.opt~ :ln.l upne.

Hawaiian fishl~onda were und~~uhtr~dlv w n product~ve areas for aquacul- ture of fishes. alpae. crabs. and shr im~. They mav have attracted and benefit- ted mohilc apecks c ~ f watirhirds that im\.iously ied only in comparatively un- productive ocean waters or unconlnlon natural wetlands. Few f~shponds exist ioday because of siltation, clogging by alien plants (es ecially red man rove, RJ~izophora mangle), overgrowth by California grass (%raSltiaria,mut(ca~, pollution, tsunami, lava flows, earthquakes, and overall d~srepa~r (IGkuchi 1976; Apple and Kikuchi 1977).

Irriented Fields: lividcncc for irrigated fields dating back to 600 A.D. has hecn recorded Tor Ilanalei Valley on Kaua'i and to 1200-1400 A.D. for Moloka'i and O'ahu (Yen a a1 1972; Kirch and Kelly 1975; Kirch 1982). the last coinciding with the period of rapid human population increase. By Cap- tain J a n m ('ook's arrival in 1778, nearlv all bottomlands with permanent streams contained irrieation svstems. and vast areas of wetlands had been

pcm recent ectablishment in the Islands, robably dependent on wetland habitat developed by humans. Whether tRis is true or not, populations of thebe bird, and probably others such as now-extinct ra~ls (Ralhdae) and ihises (Plataleidae) may have responded to mcreased wetland hab~mt. I'olynesian hunters. rats (Rarrur exulunc). and avian predators may also have henefit- ted from increased availability and numbers of some birds in the anthro- pogenic habitat.

Vegetation Many lowland freshwater ponds have a central area of free water sur-

rounded by emergent vegetation rooted in the soil of pond margins. In less disturbed ponds, vegetation of the shallows is dominated by indigenous grass- like lants called sedges, particularly tall bulrushes such as makai (Bol- bosc f: oerucr mari?imus subsp.paludosus) and 'aka'ukaz (Schoenoplectus lacustrir

o~alidw), and the less robust makaloa (Cyperur laevigatw). In some :%and wetlands, the even'larger California bulrush (Schoenoplechrs californicusj, probably not native to Hawai'i, grows intermxed with native bulrushes or 1s the dominant plant. Other native plants often seen at the edges of ondc in muddy areis are water hyssop (Bacopa monnirriu), heach dropseecfgrass (Sporobolu~ vrrginicu.~), and .~~k~ilikuli,(.Si?rr~ ium pomila- cn~rrum). Where water i< brackish, the introduced plckle weed (Uuti.~ maritima) now dominates. Non-emergent freshwafer aauatic veeetation erow- ing in pohds. reservoirs, or slow-moviig streams includhs floatin; plants and suhmeraed or partially submerged plants with~~ut well-de\.eloped a~.pporting tissue. Manv aouatic blants are imbortant foods for waterbirds.

An unu;ual'type hf wetland thit i< today restricted 10 a few localities on O'ahu is the y g . d (spring) m, in which natural vegetation is composed of the rare water fern 'il~i'ihi lauakea (Mmilea villo.~~), a Candidate Endan. ~ e m d soecies. These oools occur inverv dm. leeward lowlands, orimarilv in - - ~ - ~ ~r~~~~ ~ ~

craters or other depr&&ns. Standing hati; is present only seaionally, ' during periods of heavy rwnfall. I h e remainder of the year, the soil is d ~ y and tEiwater fern turis brown and meatlv decrease> in cover. Well a d a ~ t e d to such extreme fl~muations in moishre, (he endemic Maoileu persists ;I'nd holds its own despite the presence of many alien plant specir.5.

Apart from vernal pools, natural wetland vegetat~on in tlawai'i is charac- terbed hy a relatively low percentage of endemic plants. Most native wetland plant spccies arc 3120 found in similar habitats on other Pacific islands and In tror~icnl regions on continents. Fven though Hawaiian wetlands cannot he consi;lered rish sitcs for rare plants, their resiricted distribution, small size. importance to native animds, and the danger of destruction hy development are compelling reasons for the conservation of what remains.

Cultivated wetlands are usuallv dedicated to taro in Hawai'i. but a num- ber otutedsrangingfrom herhacious to woody species also invide on diifcr- ent substrates and with diffcrrnt amounts of cultivnrinn. Watercreqs Ih'a~t~mium mi~~ronl~dlun~l . l o t ~ ~ s (Nelun~ho nucifera). and rice (Orvza sarivu) . , i r e also grown in limited quantitiks.

Birds of the Wetlands ~ - ~ - ~ ~ ~ ~~

Six specles of nattve Hawaiian birds are dependent upon natural and cultivated freshwnrer wetlands in Hawai'i. The Federally Endangered 'aloe la, alw called Hawaiian gallincle or moorhen (Gallinula cltloropus sand- vicensi,i), and the ‘slat= ke'oke'o or Hawaiian coot (Fuliru ameticanu ulai) are all that remain of I I known specier of the rail family present when the first Polynesians arrived. noth birds are currently considered wbs cur\ of Uorth

' ' - . American forms and prefer either th~ckly vegetated marihlnn w~th assoc~ated open water or taro fieldr. Sesting moorhens arc abundant in taro fields on Kaua'~ at llanalei National Wildlife Refuge; and on O i h u at Paradiye Pacifica (in deep ponds with a bulru\h marsh), at Jamr.5 Campbell Sational Wildlife Kcfuee. and in Hale'iwn lr~!us fielL',. Ilawaii:m zmts prefer more open water th%gallinules and tolerate a range of fresh to saline (rarely)

conditions, such as are present in ancient coastal fishponds and at Pearl Harbor National Wildhfe Refuge (US. Fish and Wildlife Senrice 1985). Coots have probably always been numerous on O'ahu, Maui, and Kaua'i.

The Endangered Hawaiian stilt or ae'o (Himantopus meticanus ecies of the North American form. Stilts are still known

except Lana'i and Kaho'olawe and favor small salt water for nesting. They often feed in shallow

freshwater, brackish, or saltwater areas other than those in which they nest. In recent yean, the estimated population size has been 1,200-1,500 blrds (Scott ef aL 1988), but numbers have varied widely in the past.

The Endangered Laysan duck (Anus laysanemis) lives only on Laysan Island in the Northwestern Hawaiian Islands, and several hundred hirds remain. The Endangered koloa maoli or Hawaiian duck (Anus wyvilliana) is now found mostly on Kaua'i in montane stream habitat between 1,000 and 4,000 ft (300-1.200 m) elevation. Apopulation has been reestablished in the Kohala Mountains on Hawai'i through the State captive breeding program (see Giffin, this volume). The hirds use stock ponds, reservoirs, irrigation ditches, and native stream habitat (US. Fish and Wildlife Service 1985). On O'ahu, koloa maoli are found on James Campbell National Wildlife Refuge, Punaho'olapa Marsh at Kahuku, and other wetlands.

The 'auku'u or black-crowned night heron is not considered a distinct Hawaiian subspecies of the mainland species (Nycficorox nycticorox). It nests on all the main islands in wetland habitat. It is a predator on fishes, crustaceans, and the young of other marsh hirds and has become a pest at aquaculture facilities. Its numbers have increased in recent years. Another bird of the wetlands, although also found elsewhere, is the introduced cattle egret (Bubulcus ibir). It is sometimes a hazard to aircraft near airports, and, like the 'auku'u, it preys on the young of marsh hirds.

Migratory shorebirds, which use marine and freshwater wetland habitat while they winter in Hawai'i, include the 'ulili or wandering tattler (Heteroscelus incanus), the 'akekeke or mddy turnstone (Arenaria interprer), the hunakai or sanderling (Calidris alba , the kioea or bristle-thighed curlew L (Nemenius tal~itienris), and the kolea or acific golden plover (Pluvialis dominica); the last is often found far from wetlands, in astures and subur- bia. Most migratory shorebirds are more adaptable to uman activities than are the resident native waterbirds in Hawai'i.

R Problems

hr\s ofwetland habitat, both natural and man made. has hccn continual since ar leas1 the 1850s. Taro fields and rice paddies have been replaced by other agricultural crops such as sugar cane (Saccharum officinanrm) and by development, until only a few hundred acres remain in wetland agriculture. Hotels, golf courses, housin developments, shopping centers, landfills, high- ways, military and industriafsites, and other crops have replaced extensive Polynesian wetland systems as well as natural habitats. Modern aquacultural areas, stock ponds, dltches, settling ponds, and golf course water hazards are used by waterbirds in Hawai'i today. However, they probably cannot replace the loss of areas such as Waikiki marsh, the Ahuimanu, Salt Lake, and Ke'ehi wetlands, Kuapa and Ka'elepulu ponds, and Hawaiian fishponds and flooded taro fields.

Introduced lants such as California grass, pickle need, mangrove, and water hyacinth &iclzomiacra.%sipe.~) have reduccrl open water, muJil;~i,

and shallows used bv birds (Shallenber~er 1975). Mammals such as feral - ~

cats, mongoores, dois, and k ~ t s (I.'clir c;trrs, Hi?r~m~es ulrropunctutus, Cuni., famil~urir, and Hatru~ spp.) and other introduced avian predalm such ac the 'cattle eeret have r e d u d breeding success of waterbirds. Human disturbance of birds% limited habitat, especia?ly during avian nesting seasons, has also reduced nesting success. A well-publicized oil spill adjacent to a marsh in Pearl Harbor, O'ahu, recently disturbed waterbird nesting efforts in a U.S. Fish and Wildlife Service National Wildlife Refuge, a "protected" area.

When breeding birds use cultivated wetlands, disturbance during the nest- ing season often becomes a problem. For example, at Hanalei National Wild- life Refuge on Kaua'i, it is necessa for taro plants to be left around active nests during harvest. The effects o ?' water level management of flooded crop- lands on birds and their food plants must also be considered. Boating activi- ties, including tourist trips and filling of boat engines on the Hanalei River, have been restricted during waterbird nesting season. Temporaly fencing is used to reduce predation in some areas. Pesticides (for example, heptachlor) are special hazards to birds dependent upon agricultural fields for feeding and breeding.

Conservation of Birds Hunting of all wetland birds, one of the major factors in population de-

clines, stopped in 1941 in Hawai'i, and a captive breeding program for koloa maoli has been in operation since 1958 (see Giffin, this volume). A State wetlands sanctuary system for waterbirds was begun i u Hawai'i in 1952 with Kanaha Pond (145 acres or 59 ha) on Maui, followed by nearby Kealia Pond (385 acres or 156 ha). The koloa and 'alae \la were listed as Endangered in 1967, and the stilt and coot followed in 1970. Hanalei National Wildlife Refuge (917 acres or 367 ha) was created on Kaua'i in 1973, followed by Hule'ia National Wildlife Refuge (238 acres or 95 ha) also on Kaua'i in 1973; Kakahai'a National Wildlife Refu e (45 acres or 18 ha) on Moloka'i in 1976; and Pearl Harbor National wildlife Refuge (61 acres or 24.5 ha) and James Campbell National Wildlife Refuge (142 acres or 57 ha) on O'ahu in 1976. An additional State sanctualy (Paiko Lagoon) and two sanctuaries on milita~y land (Nu'upia Ponds and Lualualei) on O'ahu have also been established. Two of the most valuable breeding and nesting sites on leeward Hawai'i Island. Kaoo'ikai Pond at Makalawena and Aimaka~a Pond at Honokohau. &re slsted;or protection in the near future.

Active mnnhgment on .ome r e h -es, s:inctuaries. and management areas hac included: development of xrificial nesting structures for birds: habitat improvement such as clearing vegetstion, planting hird foods, and manipulat- ing water level to cnhancr h3bitat; fencing and predator control hv trapping 10 reduce predation; reduction of human disturbance; and annual and semi- nnnu:~l population counts to monitor population ircnds. Completion o i the llawalian Waterbirds Recnver?. Plan in 1977 provided objectives ndcessaly fdr removing birds irom thc 1;etleral Endangered Species list.

STREAMS

Most of Hawai'i's 366 perennial streams (on five major Islands) have had some form of water diversion or alteration. Less than 14% are physically pristine (Parrish et al. 1978), and far fewer are biologically intact. Many

streams drain small areas, and only two, the Hanalei River on Kaua'i and the Wailuku River on Hawai'i, discharge over 150 million ~a l lons per day 6.6 mL/sec Most of the rest average less than 50 miliion galions per day

l1.2 m2/sec{'(Armstrong 1983).

Animal Life In addition to native insects. Hawai'i's freshwater streams contain fishes.

. , :ca and il,,at plankton tor :I iinic 'l'he /I;II.II~LI or iingrling gd)ie< return to f r c ~ ~ t i \ \ ; ~ ~ e r ,trc:un, I,) 1n:uure and :pa\<n. :t i do \ w n g 4irimp and m:t.I\. l'lank~oni,~ diqwr~;tl ; i m r n < the l l : l ~ ~ ; ~ i ~ : 8 i ~ 1~l.uid~ I. cfii~.ici~t, a5 h n m I)\ t h ? fact that few species of freShwater gobies (five), shrimp (one), and snail< (one) have become isolated and evolved in the Islands. Further evidence of efficient planktonic dispersal is the fact that the newly introduced Tahitian prawn (Macrobracl~ium far), with a freshwater and ocean life cycle s~milar to that of the native shrimp, had spread to most Hawaiian streams 10-15 years after its introduction to only two streams.

Adult native damselflies and dragonflies orpinao (Megalagrion spp.) and their predaceous larvae (naiads) or lohelol~, together with adult and larval midges (Chironomidae), crane flies (Tipulidae), shore flies (Ephydridae), and other insects. comorise uniaue food chains associated with Hawai'i's fresh- water strc;rnis. ~ h ' e d ; ~ m ~ e ~ h i ' ~ < are excellent euniplc.; of adap!ir,e radiation. u,ith 2h rpecieq 11,ing a rturnher oidifir ,rm a(,uatic and terre~trial niches i n

Iisw;,i'i. Some auuit:c iorm> >l,o dcpenJ uDon nutrient, from insect, or decomposing fruik and vegetation thi t drodinto streams from adjacent habitat. The introduced long-legged ant (Anoplolepi.~ longipes) threatens stream hiota such as pinao.

Problems Fresh water on oceanic islands is especially precious for a ricultoral, f industrial, and individual use. Diversion and channelization o streams by

humans for these purposes or for flood control is a continual threat to stream life. even in lowland areas. because most island freshwater animals need the cpnncction to thc he3 1 0 coml~lcIe their life cyles. A~ricultural chentic~I>. Sll[stion, m~nicipal wastes, alien specics, and ch:inge\ i n turbidit!. oxygen content. fluu rate. and u:rter tenlpersture can a 1 create c u n d ~ t ~ ~ . r i to u hich native a'ouatic animals are not adanted and with which thev cannot survive - .~7.~-.~. ~~~ ~ ~

Feral an~mal, and livestock, or lanh u\e practice, that rembve s t rean idc plant covcr that nrovideh ?h;de. change temperature and light cond~tims 10 which stream an/mals haw suaptctl, &cres,i nutrient, andlioil in the uster. and efiecti\ely degrade or destroy hahitat ior bq~latic orgsnism%

Conservation Protection of the few remaining pristine freshwater streams in the State

Natural Area Reserves System or in preserves managed by The Nature Con- sewancy of Hawaii, or protection in other ways, is vital. A new State Water Code provides a Commission on Water Resources Management to establish what water resources should be protected as habitats for fish and wildlife. Forty-bur streams on Kaua'i and East Maui have been pro osed for protec- tion from water diversion under standards required by the $ tale Water Code. In 1988, legislators asked the State Commission on Water Resources to set up a Wild and Scenic Rivers System. Some of the im ortant remaining fresh- water streams include Kahana Stream on O'ahu; 8 ahakuloa and Hanawi on Maui; Waimanu on Hawai'i; Kilauea, Hanalei, and Lumaha'i on Kaua'i; and Wailau and Pelekunu on Moloka'i.

Protection o i streamside vegetation to pre.erve natural atluatic tempers- ture and light conditions and sources of food for stream organisms is impor- r:m. Feral ;~nim;~ls and livestock s h o ~ l d be removed from watersheds drained by nearly pristine streams, and prevention of pollution from development and agriculture In these areas should be emphnsi7ed. Channclizlttion projects t l u r result in replacement of natural substrate with artific~al hottom material, reduction of stream channel length, and vegetation removal should be avoided where feasible (Parrish et aL 1978). Hydroelectric facilities have potential adverse impacts such as blockage of fish migration and stream diversion, al-

and crustaceans were recorded, only eight of which were native. Native stream species were found to thrive only in areas free of development (Parrish eta!. 1978).

Active conservation education about the value of Hawaiian streams is alco necessary if we are lo preserve the few unmodified streams that rcmain. I h e Conscwatiiln Council of Hlwaii po.tcrs tm aquatic life, xvailahle irom environmental groups. are excellent educational aids to h e l ~ inform the puhlic about conservai;lon ;dues and problems.

ANCHIALINE POOLS

Physical Character is t ics Anchialine ("near the sea") waters occur around the world in lava and

elevated fossil reefs. In the Hawaiian Islands they are found on O'ahu, Maui, Moloka'i, and Hawai'i but are most abundant on Hawai'i Island and Maui (The Nature Consewancy of Hawaii 1987). There are an estimated 600-650 on Hawai'i, perhaps 50 on Maui, 3 on O'ahu, and one on Moloka'i, most on orivate lands. The term "uool' includes mica1 small bodies of water as well i s water in cracks, open wells. and place; h d c r lava rock overhangs (Maciolek and Brock 1974). About half of 318 pods surveyed along Hbwai'i Island's leeward (Kona) coast showed cultural modification, by either Poly- nesians or modern humans. Prior to arrival of Europeans, Hawaiians used anchialine pools as potable water sources, as hathing ools, and a!. iish onds Althoueh all larcer oools ilareer than 0.02 acre or 10 f m2surface areaywer; modrfiLd, many Lave revekred to more or less natural conditions through lack of use in recent year,. Surface a r e s of 91% of the Kona pools were Iesr than

0.02 acre (100 mZ), and 91% had depths less than 5 ft (1.5 m). Some ponds surveyed held water only at high tide. Almost no physical or biological data have been collected from about 175 pools between Hilo Bay and South Point on Hawai'i Island (see Yuen, n.d.).

Salinities (where seawater = 35 parts per thousand and fresh water = 0) were less than 15 parts per thousand for 93% of 298 ponds sam led on Hawai'i Island. However, salinity varies with evaporation in di ! ferent sea- sons, tidal influx, and changes in groundwater resulting from rainfall fluctu- ation. Variations in salinity were usually less than a few parts per thou- sand for a given pool (Maciolek and Brock 1974). Surface tem eratures of 210 ponds ranged from 35' to 63O F (19-35' Cb, with 71% o&e ponds having surface temperatures between 43" and 50 F (24-28O C).

Pool Life In contrast to anchialine pools, coastal ponds with surface connections to

the sea usually contain a diversity of species, and most of them are marine. Anchialine pools, with only subterranean connections to the sea, have fewer but more distinctive animals (Maciolek and Brock 1974). Crustaceans and mullusk.i arc the most :ihunhnt and ch;~rdctcr~\tic anilnsls i n thc,e eco,yr- [ems, and m n e arc apparentl! L- 11) :mchicl.ine ecoswcmh. .\linutc, red. herbivorous shrimu or 'or~rr~ irlo illuk~crrri,lbu~ ruhra) are orohahlv the most characteristic spe'cies, b i t several other crustaceans'and &me mdllusks and fishes are also quite typical. 'Opae 'ula mixed with red cinders were valued aspalu (chum) to catch 'npelu (mackerel scad) by ancient Hawaiians (H. S ringer, personal communication).

Algae of dif ! erent forms were present in all anchialine ponds surveyed on leeward Hawai'i, and many serve as food for aquatic animals and add to the complexity of the pool habitats. The indigenous aquatic vascular plant tassel pondweed or widgeon grass (Ruppia rnaritima) is also characteristic of lee- ward ponds on Hawai'i Island.

S I ~ L . of the 55 animxl ipecxs prr.\ent ncrc r.on\idered ~ e \ e n t a t i v c oi Kon:~ :~nchixl~nc pools (\1asiolck and llrock ILJ74). 1 hcsc included: Ar~immr*o 511.. a .;m;~ll sn31l H I \ O found on damp beaches: Alcluni~r sp.. 3 lareer snail -bidelv distributed in streams and lowland uonds: Theadoxus

u

curiosu, ;I h l ~ k limpet-line \nail ;ilw found in ew3r i i s jnd hrackihh hays; .I!mrh,v~nrr k,lr,w~, a small rcd shrimp limiled to anchialine water> and predaceous on 'opae 'ula, also limitedto anchialine waters; Paluemon debilis or 'opae hum, a medium-sized, largely transparent shrimp common in estu- ?ries and protected inshore waters; Macrobrachiurn grandimanus or 'opae oeha'a. a lareer s h r i m ~ from estuaries and streams; Eleofris sandwicems or

A number of other rare species of invertebrates, including six shrimps.

Some variants of more widely distributed forms are also characteristic

Conservation Anchialine pool inventories need to be completed to determine the most

valuable areas to protect. The Nature Conservancy of Hawaii and the U.S. National Park Service are among the current sponsors of such surveys, and the Conservancy has recently completed a biological database (The Nature

Conservancy of Hawaii 1987; see also Newman, this volume). Maciolek and Brock (1974) resented a number of recommendations based on the results nf

~~ ~ . . their survev. Most of the pristine pools that they recommended highly for preservation were in remote locdt~on.; and of pbrticular importance h e c x ~ s e of their use by waterbirds, or because of theiranthro ologkal value. The US . Fish and Wildlife Service has classified one ancfialine pool mollusk, seven crustaceans, and a rare moray eel as Candidate Endangered species (John I. Ford, ersonal communication). Three of the crustaceans are new species recent& discovered a t South Point, Hawai'i Island (Kensley and Williamc 1986) . . -. .. . - , - .

Maior thrdats to anchialine ~ o o l s include develo~ment and alien s~ecies . ~. Nntivc rind alien fishes in pools do not appear to coexist well, and fiche's (cqecia ly introduced hshc>) and shrtmp,alsnx-em ~ncompatilrle (Jlaciolek and Brock 1974). The inflt~ence of D:trt 1.1wa11an culture on thc ~ o o l s has been slight, but the degradation or destruction caused by modem human use threatens many areas of substantial about one-third of Big Island anchialine pools have been destroyed by hotel development in the d~strict of South Kohala.

CONCLUSIONS

Wetlandc, streams, and anchialinc p o d s are among the most threatened of Hawaiian environments because they are located .r.herc con~licts with other human nee& are increasing dramatically. I t is essential that research and monitoring to detcrmine t l x valuc, status, :md ~ n t e r r c l a t i m s h ~ p of the hio- logical resources involved be supported. I'rotection of the best sites and edu- cation.~l program\ to enhance under>tmding a h m t these xeab should a lw be stressed. I'reservation of a network of natur:tl and modified wetland5 and pc~ds , togetltcr \r ~ t h adjacent dec,pw;rtcr ht~hltat including %treatns snd m m n c areas, presents a t~nique opport~tnity to coordinate historical. cultural, eco- nomic, . ~- snd l>iological ~ d u e , in the areas most u\ed and ahused by h ~ ~ m : m in Hawai'i.

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