Nasoata Mangrove Island, the PABITRA Coastal Study Site for Viti Levu, Fiji Islands

Thaman, Randolph R. Keppel, Gunnar. Whatling, Dick. Thaman, Batiri. More

Pacific Science, Volume 59, Number 2, April 2005, pp. 193-204 (Article)

Published by University of Hawai'i Press DOI: 10.1353/psc.2005.0027

For additional information about this article http://muse.jhu.edu/journals/psc/summary/v059/59.2thaman.html

Access Provided by Curtin University of Technology at 01/11/12 6:18AM GMT Nasoata Mangrove Island, the PABITRA Coastal Study Site for Viti Levu, Fiji Islands1

R. R. Thaman,2 Gunnar Keppel,3 Dick Watling,4 Batiri Thaman,5 Timoci Gaunavinaka,6 Alifereti Naikatini,7 Baravi Thaman,8 Nemani Bolaqace,9 Etika Sekinoco,9 and Manasa Masere9

Abstract: Nasoata Island is a predominantly mangrove island located near the outflow and delta of the Rewa River, Fiji’s largest and longest river. The river originates on the eastern slopes of Mt. Tomaniivi in the Central Highlands of Viti Levu. The island has been selected as an integral coastal site for Fiji’s PABITRA Gateway Transect. Information is provided on: (1) the reasons it was selected as a PABITRA site; (2) geographical, geological, climatic, and eda- phic setting; (3) the vegetation; and (4) brief notes on the fauna, with particular focus on the avifauna. Because of its rich flora and fauna, Nasoata Island is an excellent ‘‘prototype’’ coastal and mangrove site for enhancing our understand- ing of the complexities of island biodiversity, both within Fiji and in relation to other small offshore islands within the broader PABITRA network.

Nasoata is a small, predominantly man- as a prototype coastal mangrove site in the grove island located in the Rewa River Delta, PABITRA mountain-to-sea landscape tran- near the outflow of the Nasoata River, one of sect originating at Mt. Tomaniivi and the the main subsidiary channels of the Rewa Central Highlands of Viti Levu and extend- River, Fiji’s largest and longest river, which ing along the Rewa River system to the coral empties into the Pacific Ocean in south- reefs and nearshore marine ecosystems of eastern Viti Levu (Figure 1). Because of its southeastern Viti Levu. relatively pristine condition, its relatively rich The information presented here is based flora, avifauna, and marine biodiversity, par- on five reconnaissance visits to Nasoata be- ticularly its migratory birds, seabirds, and tween April 2001 and August 2002, during waterfowl, and its rich mangrove-associated which time preliminary assessments were crustacean fauna, the island has been selected made of the flora and fauna of the island and the surrounding nearshore environment. Based on these preliminary assessments the 1 Manuscript accepted 27 April 2004. island was first selected as one of Fiji’s prior- 2 Professor of Pacific Islands biogeography, Univer- sity of the South Pacific, Suva, Fiji Islands. ity mangrove wetland sites under the Ramsar 3 Assistant lecturer in biology, University of the South Wetland Convention and subsequently for Pacific, Suva, Fiji Islands. designation as the coastal and mangrove site 4 Environmental consultant and ornithologist, Envi- within the proposed Fiji PABITRA Gateway ronmental Consultants Fiji, Ltd., Suva, Fiji Islands. 5 Scientific officer, Institute of Applied Science, Uni- Transect. The main reasons for its selection versity of the South Pacific, Suva, Fiji Islands. include (1) it is an uninhabited offshore is- 6 Coordinator, Fiji National Ramsar and Wetlands land, which makes it an excellent site for the Working Group, Suva, Fiji Islands. study of processes within a discrete small- 7 Technical assistant, South Pacific Regional Herbar- island ecosystem surrounded by more diverse ium, University of the South Pacific, Suva, Fiji Islands. 8 Tutor in geography, University of the South Pacific, ecosystems of main-island Viti Levu; (2) it is Suva, Fiji Islands. a relatively undisturbed and extensive man- 9 Community leader, Nakorovou Village, Rewa Prov- grove ecosystem with a diversity of associated ince, Viti Levu, Fiji Islands. flora and fauna; (3) limited areas of other representative coastal and nearshore marine Pacific Science (2005), vol. 59, no. 2:193–204 ecosystems exist, which support beach and lit- : 2005 by University of Hawai‘i Press toral forest, disturbed coastal forest, a coco- All rights reserved nut plantation, intertidal sea-grass beds, and

193 194 PACIFIC SCIENCE . April 2005

Figure 1. Annotated aerial photograph of a portion of southeastern Viti Levu centered on Nasoata Island and the lower reaches of the Nasoata River showing the main mangrove islands of Nasoata, Valolo, and Sagasaga; portions of the Rewa River Delta; fringing reefs; mudflats and associated intertidal sea-grass beds; offshore barrier reefs; reef passes; and the locations of Nakorovou Village (the custodians of Nasoata) and other Fijian villages that use the area as an important fishing ground and the islands as sources of food and other products.

mudflats; (4) its pivotal location on the wind- sible for the stewardship of the island and by ward side of Viti Levu at the mouth of the the Fiji Government. Rewa River and just off the main delta, about 1 km inside the main barrier reef, makes it a geography, climate, soils, and tenure prime target for potential colonization by ter- changes restrial and aquatic organisms from both the sea and the mainland; (5) the rich shorebird The area of Nasoata is about 76 ha (0.76 and seabird avifauna; (6) the rich mangrove km2). Its maximum elevation above mean sea invertebrate and vertebrate fauna of consider- level is about 1.2 m in the higher south- able economic and cultural importance; (7) central portion of the island. It is located at the designation of the island as a reserve and about 18 80 S latitude and 178 360 E longi- a scientific study site has been strongly en- tude. The main mouth of the Rewa River dorsed by the local Fijian community respon- is located about 3 km to the west. There are Nasoata Island, PABITRA Coastal Study Site in Fiji . Thaman et al. 195 coral reefs, including Nasilai Reef, located a out the low-lying areas of the southeastern further 1 km to the south and extending to portion of the island. This is the origin of the southeast of the island. Sagasaga and Va- the island’s name, Nasoata (literally ‘‘the pum- lolo are two smaller mangrove islands located ice’’ or place of the pumice). about 1 km to the east of the island. The island was formerly a freehold prop- Nasoata lies just off the windward south- erty run as a copra plantation, first as the eastern portion of Viti Levu and has a wet, Hedstrom Estate, and subsequently by a Mr. tropical oceanic climate. The area receives B. Garnett and most recently by Ram Singh about 3,000 mm mean annual rainfall, with from the 1950s until the late 1970s when the some rainfall being experienced on an average title to the island was transferred from free- of about 250 days per year. The average an- hold to native land under the high chief of nual mean temperature is 25C (77F) with Rewa, Ro Lady Lala Mara, the Rokotui Dre- an average monthly range of about 6C. The keti. At the time the people of nearby Nako- temperature seldom rises above 32 or falls rovou Village were designated as the owners, below 16C (Smith 1979). The southeast custodians, and main users. Although the is- tradewinds, which affect the southern coast land was a source of construction materials of the island, are relatively consistent during for traditional Fijian houses (bure)inthe the cooler, drier season between April and past, the island is now used almost exclusively October. They shift more to the northeast as a fishing ground (iqoliqoli) or ‘‘breadbas- later in the year. During the warm, wet sea- ket’’ (ikanakana) and for the production of co- son between mid-November and mid-April pra from the existing coconut palms on and the entire Fiji group experiences gale-force around the old copra estate in the southeast winds. Destructive tropical cyclones, storm of the island. The island was used during waves, and associated heavy rainfall are com- World War II by New Zealand and American mon during that period. This leads to flood- troops as a training ground for jungle combat ing and accelerated runoff in the Rewa River and, more recently, during the 1970s and system and accelerated erosion on the south- early 1980s by the O Kei Viti group of Na- eastern windward side of the island. This korovou as a tourist destination, where Fijian increased river flow brings with it increased cultural displays and meals were provided as a sediment loads that affect not only the central source of income to the village. It remains a low-lying portions of Nasoata, but also the favorite picnic site for schools in the area. surrounding sea-grass beds and nearby coral reefs. The increased river flow with its high flora sediment load also substantially reduces the biogenic proportion of beach sand on the The flora of Nasoata is composed of some more upraised southern portions of the is- 123 species of vascular plants from 54 fami- land. The high river flows and storm waves lies. Of these species, 15 are ferns or fern also bring flotsam and propagules of many allies and the balance consists of 108 angio- inland plants to the island. The presence of sperms, of which 32 are monocotyledons and some of the noncoastal plant and animal spe- 76 dicotyledons (Table 1) (see Appendix for a cies found on the island, including some rep- listing of the flora). Four of the monocotyle- tiles (e.g., geckos and skinks) and countless don species are sea grasses, from two exclu- insects, is probably due to these storm-related sively aquatic families. All of the ferns are events. During one visit to the island in Au- assumed to be indigenous, whereas 36 of 106 gust 2001, just after heavy flooding in the angiosperms are probably introduced species, Rewa Delta, a juvenile Pacific boa, gata (Can- half of which (18) are assumed to be either doia bibroni), was found in a tree just behind accidental introductions by humans or recent the beach on the southeastern corner of the natural arrivals to the island carried from island. High seas, reinforced by the predomi- mainland Viti Levu by the river, waves, birds, nant tradewinds, have also led to extensive or fruit bats (see Appendix). There are no deposits of pumice (soata in Fijian) through- gymnosperms on the island. 196 PACIFIC SCIENCE . April 2005

TABLE 1 Summary of the Composition of the Flora of Nasoata Island Based on Studies Conducted from 2001 through 2003 (a Detailed Listing of Species Is Included in the Appendix)

Flora Families Indigenous Introduced Total

Pteridophyta (ferns and fern allies) 9 15 — 15 Monocotyledonae (monocots) 13 22 10 32 Dicotyledonae (dicots) 32 50 26 76 Total vascular plants 54 87 36 123

Vegetation Types per canopy are up to 16 m high. Scattered throughout this community is the mangrove The main vegetation types on Nasoata in- or swamp fern (Acrosticum aureum). Also com- clude Rhizophora- and Bruguiera-dominated mon in this plant community is a range of mangrove forest, mixed tidal forest, episodic epiphytic ferns, including Davallia fijiensis, swamp forest, inland coastal forest or coconut Davallia solida, Pyrrosia lanceolata, and Nephro- woodland, littoral forest and strand vegeta- lepis sp. Less common ferns include the tion, ruderal vegetation, and sea-grass beds. climbing fern, Stenchlaena palustris, and the Figure 2 is a general vegetation map showing epiphytic ferns Vittaria elongata, Vaginularia these vegetation types. angustifolia, and Drynaria rigidula. The latter rhizophora forest (vei tiri or vei was seen as a single, large fern growing on kaka). The eastern and northern coastal a Bruguiera tree in the center of Bolavou zone of the island is dominated by Rhizophora Swamp. The other ferns are mainly found stylosa (tiri solo) and Rhizophora mangle (tiri or growing on Bruguiera and Xylocarpus trees, tiri wai), with the former generally occupying often on older, often broken branches. The the outer fringes and the latter the inner, epiphytic orchid Grammatophyllum elegans more protected areas of this mangrove forest was also seen on a number of dead trunks system. There are also areas of dense thickets and branches of B. gymnorrhiza. Lumnitzera dominated almost exclusively by Rhizophora littorea was reportedly a common component spp. along the outer edges of the central of this forest in the past but was logged out Bruguiera-dominated Bolavou Swamp in the because of its value as one of the most durable south-central part of the island. These im- and desirable woods for houseposts for Fijian penetrable thickets are known in Fijian as vei- houses. kakaka. A sterile hybrid, Rhizophora stylosa mixed tidal forest. There are also mangle, known in Fijian as selala, which is small areas of mixed tidal forest, usually on occasional in other parts of Fiji, is also found, the southern edges of the Bruguiera gymnor- but uncommon, on the island. At least one rhiza forests or in slightly raised, more selala, approximately 15 m in height, was well-drained sites on the southern and north- seen, which is similar in height to the upper- eastern sides of the island. These mixed canopy Rhizophora spp. in the area. forests are mostly dominated by either Xy- bruguiera gymnorrhiza swamp for- locarpus granatum or Excoecaria agallocha, est. Most of the poorly drained central although scattered Rhizophora spp. and Bru- swampy portion of the island is covered by guiera gymnorrhiza are also found. Heritiera an extensive mangrove swamp forest. This littoralis and Intsia bijuga are occasional trees vegetation type is dominated almost entirely in this mixed tidal forest. The introduced in- by large Bruguiera gymnorrhiza as the upper- vasive species known as pond apple, Annona canopy species, with the occasional presence glabra, is also present. Occasional throughout of individuals of Xylocarpus granatum in more this community are the large sedges Scirpo- well-drained sites. The largest trees in the up- dendron ghaeri and Mariscus javanicus. Other Nasoata Island, PABITRA Coastal Study Site in Fiji . Thaman et al. 197

Figure 2. Generalized vegetation map of Nasoata Island, Rewa Delta, Viti Levu, Fiji Islands (prepared by Baravi Tha- man from a 1994 aerial photograph). common species include the climbing vines episodic swamp forest. There are Derris trifoliata, Dalbergia canadatensis, and limited areas of relatively open forest that are Entada phasioloides; the mangrove fern, Acro- episodically subjected to swampy conditions. stichum aureum; and the epiphytic ferns Da- These are found in a number of sites that are vallia fijiensis, Davallia solida, and Pyrrosia frequently waterlogged or submerged with lanceolata. Uncommon to occasional are the brackish water, due to a rising water table, climbing swamp fern, Stenochlaena palustris, during exceptionally high spring tides associ- and the epiphytic orchids Taeniophyllum ated with heavy rains. This intermediate veg- fasciola and Oberonia halophila (the latter two etation type is restricted to a narrow belt, were seen on a Morinda citrifolia tree, the which is found mainly on the southeastern same species that hosts orchids in the part of the island slightly inland from the Veisari mangrove forest on southeastern beach forest and on the southeastern wind- Viti Levu). In one area in the southern ward border of the central Bolavou Swamp. portion of the island, in a back-beach basin, The substrate is intermediate between the the introduced invasive species pond apple muddy mangroves and sandy beaches but (Annona glabra) has established itself in lim- also includes a large proportion of highly ited areas in almost monospecific stands, acidic pumice, in various stages of break- probably in areas formerly covered with down. Common trees of this community in- Rhizophora. clude the mangrove associates Excoecaria 198 PACIFIC SCIENCE . April 2005 agallocha, Heritiera littoralis, and Barringtonia ferns Davallia fijiensis, Davallia solida, Pyrrosia asiatica on the outer edges, with Inocarpus fa- lanceolata, Vittaria elongata, Vaginularia angus- gifer, Cocos nucifera, and Hibiscus tiliaceus dom- tifolia, and Nephrolepis spp., the latter of which inating the more well-drained sites that are are both epiphytic and terrestrial. The grass less subject to saline overflow from the tidal Centotheca lappacea; the sedge Scleria polycarpa; areas. Other scattered shrubs or small trees the adventive herbs Polygala paniculata, Clide- include Morinda citrifolia and Barringtonia mia hirta, Vernonia cinerea, and Spermacoce sp.; racemosa. The latter is found occasionally in and the epiphytic orchids Appendicula reflexa, low-lying spots that are periodically swampy. Taeniophyllum fasicola, and Oberonia halophila Also common in these sites are the climbers are also present. There are rare remnants of Smythea lanceolata, Derris trifoliata, and Entada cultivation: the air yam (Dioscorea bulbifera) phasioloides. In more expansive areas of this and derris root (Derris malaccensis), which is a type, there are aggregations of Xylocarpus source of rotenone used by Fijians to poison granatum and a few individuals of Intsia bijuga fish. (others probably have been logged out in the littoral forest and strand vegeta- past, because the wood is useful for construc- tion. There are relatively extensive areas of tion purposes). Climbers and epiphytes are littoral forest and strand vegetation along the absent or similar to those in the mixed swamp south coast of the island. These fall into two forest. relatively distinct types. The first occurs on inland coastal forest or coconut the more windward southeastern and south- woodland. There are substantial areas of central coast of the island, which has been inland coconut-dominated coastal forest or strongly and continually eroded. The second woodland on better-drained sites on the occurs on the southwestern coast of the is- southeastern and southern parts of the island, land, which is eroded to a much lesser extent. just inland from the raised beach ridge. These The beaches of Nasoata differ from other areas are rarely, if ever, inundated. Much of comparable ones in having terrestrial sand the original vegetation in these areas was brought in with the river outflow mixed with undoubtedly cleared during the establishment sand from coral reef and oceanic sources. of copra plantations during the middle of These mixed sands are, therefore, likely to the last century, but there are remnants of be richer in nutrients than the sands of the original native vegetation. Recent natural most coastal littoral beaches. The accelerated recolonization by pioneer species has also coastal erosion reportedly was most pro- occurred as coconut plantations were aban- nounced during Tropical Cyclone Bebe in doned or not maintained. Native tree 1972. Many coconut palms and other large species are found scattered throughout this coastal trees were uprooted and serious ero- community. Some may have been planted as sion of topsoil along the inner margins of the multipurpose trees when permanent residents coastal vegetation occurred at that time. This were on the island. These trees include Cer- initial major erosion has been reinforced by bera manghas, Pongamia pinnata, Xylocarpus more recent storms and associated high seas. granatum, Barringtonia asiatica, Inocarpus fagi- In the outpost or frontal zone of the lit- fer, Tarenna sambucina, Dysoxylum richii, Ficus toral beach forest on the southern side of the vitiensis, Erythrina variegata var. orientalis, and island are the trees Cocos nucifera, Hibiscus the introduced Annona glabra. Shrubby spe- tiliaceus, Excoecaria agallocha, Hernandia nym- cies include Morinda citrifolia, Ficus barclayana, phaeifolia, Thespesia populnea, Calophyllum ino- Geniostoma sp., and the introduced Lantana phyllum, Cerbera manghas, Pandanus tectorius, camara. Occasional naturally occurring climb- Terminalia catappa, Premna serratifolia, and a ing vines or lianas include Derris trifoliata, few young individuals of Rhizophora samoensis; Smythea lanceolata, Entada phaseoloides, the ad- the shrub Clerodendrum inerme; the grasses ventive Passiflora laurifolia, the terrestrial fern Paspalum vaginatum and Lepturus repens; the Phymatosorus grossus, and the mainly epiphytic sedge Cyperus stoloniferus; and the spreading Nasoata Island, PABITRA Coastal Study Site in Fiji . Thaman et al. 199 or climbing vines, Canavalia rosea, Ipomoea pes- along the oceanside southern coast of the is- caprae, Ipomoea macrantha, and Vigna marina. land. The dominant species include Halophila The southwestern coast vegetation has a sim- ovalis, Halodule pinifolia, and Halodule uniner- ilar composition but also includes some iso- vis. The dominant species in the deeper, lated individuals or relicts of the original sandier subtidal areas off the intertidal flats is coastal littoral forest. These include Tourne- Syringodium isoetifolium, which is also a domi- fortia argentea and Xylocarpus moluccensis and nant component of the flotsam and drift de- the shrub Scaevola taccada. The only remain- posits along the beaches and in back-beach ing individual of red-flowered mangrove, basins. Lumnitzera littorea, is also found in the outer coastal zone along the beach on the south- fauna western coast of the island. This tree species The fauna of the island and surrounding mud was reportedly abundant on the coastal mar- flats is very rich given the small size of the gins of the mangroves in the past, but was island. Particularly important is the rich harvested for houseposts. In a number of pla- avifauna, a number of other vertebrates, ar- ces the aliens trailing daisy (Wedelia trilobata) thropods, and other terrestrial invertebrates. and Para grass (Brachiaria mutica) are success- The culturally important crustacean fauna, fully outcompeting the indigenous herbaceous shellfish, and many other intertidal marine species (e.g., Ipomoea pes-caprae, Canavalia invertebrates are present. In-depth studies rosea, and Vigna marina). These introduced have not yet been conducted on the marine plants constitute a threat to this vegetation fauna and flora. The subtidal and riverine type. ruderal vegetation. areas around the island contain a rich finfish There are fauna. Studies focusing on the diverse arthro- limited areas of ruderal vegetation found pod fauna are lacking. mainly in and around the former Hedstrom settlement, in well-drained areas formerly Avifauna utilized as copra plantations, and in a limited number of open sites in more well-drained Preliminary estimates indicate that there are parts of the island. The former site is domi- at the very least 14 species of land, freshwater, nated by Cocos nucifera in the tree layer with shore-, and seabirds resident on or visiting undergrowth dominated by the grasses Ischae- the island (Table 2). Further studies con- mum indicum and Brachiaria mutica. Occa- ducted during different times of the year and sional weedy species include Mimosa pudica, at night will undoubtedly add to this list. Vernonia cinerea, Polygala paniculata, and Of particular interest is the abundance of Clidemia hirta. In less-open areas, the under- the Pacific black duck, which is commonly growth may consist of Annona glabra, Lantana seen in flocks feeding or resting on mudflats, camara, and other introduced plants, as well including about 60 in three flocks counted as some members of the inland coastal forest from one spot during a lunch break in April vegetation. Along the southern front of the 2001. This was the largest number ever seen former Hedstrom Estate, the introduced at one time in Fiji by resident bird expert groundcover Wedelia trilobata has become es- Dick Watling, who has studied birds in Fiji tablished. It is now found in about five sites for over 35 yrs. Also common to occasional along the southern coast and constitutes a are the collared kingfisher, the wattled honey- threat to the indigenous coastal littoral vege- eater, and the Vanikoro broadbill. A rather tation and the plants that border the man- surprising, perhaps disturbing, observation grove swamp. Its eradication from the island was the presence of six individuals of the in- is suggested as an immediate priority. troduced jungle mynah in the mangroves, sea-grass beds. There are relatively ex- which has been shown to outcompete indige- tensive areas of sea-grass beds located on the nous birds, especially in disturbed habitats intertidal sand-mud flats and subtidal areas (Watling 1982). 200 PACIFIC SCIENCE . April 2005

TABLE 2 Land, freshwater, shore-, and seabirds reported present on Nasoata Island and on surrounding mudflats, based on a survey by D. Watling in April 2001

Fijian Name Common Name Scientific Name

Land and freshwater birds Belo¯ Reef heron Egretta sacra visako¯ Mangrove heron Butorides striatus ga¯ ni Viti Pacific black duck Anas superciliosa so¯so¯ Collared kingfisher Todiramphus chloris kikau Wattled honeyeater Foulehaio carunculata matayalo, solesole waqa, tina ni uto Vanikoro broadbill Myiagra vanikorensis maina¯ Jungle mynah Acridotheres fuscus Sea- and shorebirds kasaga Lesser frigatebird Fregata ariel ico¯ Crested tern Sterna bergii turı¯ Whimbrel Numenius phaeopus dilio Pacific golden plover Pluvialis fulva batibalavu, teitei kai dawa Bar-tailed godwit Limosa lapponica dilio seasea Turnstone Arenaria interpres juli Wandering tattler Heteroscelus incanus

In terms of Fiji’s shore- and seabird fauna, them to rest and feed when much of the sur- the extensive mudflats adjoining the island are rounding flat is submerged. of major interest with respect to Nasoata’s possible nomination as a conservation area Other Vertebrates under the Ramsar Wetlands Convention. Over 300 waders were observed on these Reptiles seen on the island include blue-tailed mudflats in April 2001. Most were wandering and copper skinks (Emoia cyanura and Emoia tattlers, which are the last waders to leave impar), which were common; the moth skink on their northern migration (they leave in (Lipinia noctua); the oceanic gecko (Gehyra late April or early May). Fiji’s other common oceanica); and the mourning gecko (Lepidodac- waders, the golden plovers, bar-tailed god- tylus lugubris). Neither the snake-eyed skink wits, and turnstones, already would have (Cryptoblepharus eximius) or the green tree commenced their northern migration, which skink (Emoia concolor) were observed but accounts for their low numbers at that time. may well occur. As mentioned above, a juve- Also relatively abundant were whimbrels, nile Pacific boa, one of Fiji’s two native land seen off the southern beach. If these waders snakes, was also seen in a coastal tree after a occur around Nasoata in the same proportion major flood that swept past the island in Au- as they do at Suva Point, where the numbers gust 2001. It has not been seen since. are regularly monitored, then peak numbers The only indigenous terrestrial mammals in February to March at Nasoata are esti- are nonresident fruit bats (Pteropus tonganus), mated to be approximately 900–1,000, a very which fly from the mainland to feed on the impressive number by Fijian standards. The island. Of concern is the presence of the in- other bird seen in substantial numbers was troduced mongoose (Herpestes auropunctatus), the crested tern, of which some 50 were seen which is common on the island and is a resting on flats adjacent to the island. Two major threat to ground-nesting birds and of these mudflats are quite elevated and con- crabs. Rats (Rattus spp.) may also occur on centrate the waders as the tide rises, allowing the island. Nasoata Island, PABITRA Coastal Study Site in Fiji . Thaman et al. 201

Terrestrial Invertebrates Commonly collected mangrove-associated shellfish include mangrove oysters, dio (Cras- Although formal studies have not been con- sostrea mordax); nerite snails, sisici or telei ducted, preliminary studies conducted by a (Nerita spp.); periwinkles, sisi ni veidogo (Lit- PABITRA team in November 2002 indicate torina scabra); sponge-finger oysters, drivi that there is a relatively diverse terrestrial (Vulsella vulsella); mangrove mussels, kuku invertebrate fauna. This includes a range of (Modiolus agripetus); and saddle tree oysters, centipedes and millipedes, spiders, butterflies, civaciva (Isognomon ephippium). These are not moths, stick insects, grasshoppers, beetles, commonly sold and are used mainly for sub- flies, bees, wasps, ants, and other insects, most sistence. Other edible shellfish found on the of which have important ecological roles mudflats include ark shells, kaikoso (Anadara on the island. The wide range of specimens antiquata)andkaibakoko (Codakia spp.); venus collected in 2002 still awaits identification. clams, qeqe or qaqa (Gafarium tumidum); and moon snails, drevula (Polynices spp.). Also common on the mudflats are lamp shells, Marine Fauna ivoce (Lingula unguis); peanut worms, ibo (Siphono- The most immediately obvious components soma australe); and the sandfish or dairo, a spe- of the marine fauna are the economically and cies of beˆche-de-mer (Metriatyla scabra). culturally important crustaceans that abound Commonly caught finfish include qitawa on the island. Most notable is the mangrove (Terapon jarbua); ki (Upeneus vittatus); kaikai or mud lobster or mana¯ (Thalassoma anomala), (Gazza minuta and Leiognathus equulus); kake which is caught using an ingenious traditional (Lutjanus fulviflamma); matu (Gerres spp.); snaring system. It is in season between De- damu (Lutjanus bohor); kurukoto (Eleotris mela- cember and April and sold at local urban mar- nosoma); kawakawa (Epinephelus spp.); nuqa kets as an important source of income. There (Siganus spp.); kabatia (Lethrinus harak); ka- are two species of mangrove crabs, the red- nace (Crenimugil crenilabi, Valamugil saheli); clawed mangrove crab or kuka damu (Sesarma molisa¯ (Liza melinoptera or small mullet); and erythrodactyla) and the black mangrove crab, freshwater eels, duna (Anguilla marmorata) kuka vulu or uka loa (Metapograpsus messor). (Thaman 1998). Some of these fish are sold, There is also the larger mud crab, qari (Scylla although most are consumed in the local serrata). These three crab species are com- communities. The mudskipper, tidrai (Peri- mon in the mangrove habitats. In addition, ophthalmus argentimaculatus), is also common the land crab, lairo or tuba¯ (Cardisoma carni- but not eaten. flex), is found in more well-drained sites. All of these species are hunted in season and conclusions sold at local markets as an important source of cash income. Commonly caught prawns The observations made during seven trips to or shrimp include ura (Penaeus spp.), kadikadi Nasoata Island in 2001 and 2002 have con- (Macrobrachium equidens), and moci (Palaemon firmed Nasoata as a prime mangrove study concinnus). These species are also sold. The site, which offers a wide range of opportuni- rock crab, taqara (Grapsus albolineatus); the ties to conduct controlled studies of the box crab, cugavotu (Calappa hepatica); and a mangrove ecosystem and other associated ter- number of species of fiddler crabs, toto (Uca restrial, riverine, and marine ecosystems sur- spp.), and hermit crabs, uga (Ceonobita spp.) rounding the island. The island constitutes occur along the coastline or on the mudflats. a good example of a ‘‘classical’’ Rewa Delta The latter is considered a preferred bait mangrove ecosystem with fringing tiri (Rhi- species for line fishing. Penaeid prawns or zophora spp.) and extensive mature stands of shrimps (Penaeus spp.) are common on the dogo intertidal swamp forest (Bruguiera gym- reef flat and are seasonally caught for local norrhiza), known as Bolavou Swamp. Scat- consumption and sale. tered throughout the island, mostly on the 202 PACIFIC SCIENCE . April 2005 southern margins of Bolavou Swamp, are In short, Nasoata Island is an accessible, slightly raised areas with impressive stands of complex mangrove ecosystem with associated dabi (Xylocarpus granatum)andHeritiera littor- terrestrial, freshwater, and marine ecosys- alis. This mangrove swamp forest is as im- tems. It is ideally located at the extreme pressive as any seen anywhere in Fiji. With southeastern end of the PABITRA Gateway the exception of reported widespread removal Transect, which extends from cloud forest of Lumnitzera littorea (now a critically threat- to mangrove and coral reef ecosystems. The ened species on the island), the current use PABITRA Gateway Transect includes Fiji’s of the island seems to be on the whole non- largest river system, the Rewa River and its destructive. Overall the mangroves look al- upstream catchments and lower delta, as an most untouched, whereas many similar areas integrated system. The high level of terres- on mainland Viti Levu have had some log- trial, freshwater, and marine biodiversity, ging. However, Nasoata was never included including the presence of some introduced, in the Forestry Department’s plan for the ex- potentially invasive species, also adds to the ploitation of timber and firewood in the Rewa value of the PABITRA landscape for the mangroves. study of interacting ecosystems. The fact There are a number of introduced plant that the island is seen by the local user com- species that have been shown to have been munities as their ‘‘breadbasket’’ (ikanakana) highly invasive in other areas of Fiji. These and is currently being used in what appears include the trailing daisy (Wedelia trilobata), to be a sustainable manner, adds an important which was seen in five locations on the human dimension, so central to the PABI- southern coast of the island. This plant has TRA philosophy. Finally, the strong support invaded mangroves, river courses, and coast- from the local communities, who are respon- lines on mainland Fiji and other areas in the sible for caring for and using the island, for Pacific Islands and could become one of the the designation of the area as a conservation most invasive weeds in the Pacific Islands. It site and scientific study area further adds could lead to serious ecological disturbance, to the importance of Nasoata Island as an particularly on small offshore islands and in integral component of the Fiji PABITRA mangrove ecosystems. The pond apple (An- Gateway Transect. This also underlines its nona glabra) is naturalized in limited areas suitability for designation as a priority site of back-beach swamps on the southeastern for protection under the Ramsar Wetlands portion of the island, where it now forms al- Convention. most monospecific stands of large trees. Also of concern is a member of the pepper family, the hooked pepper bush, Piper aduncum.It Literature Cited is currently uncommon but has become a se- rious weedy large shrub in coastal areas else- Smith, A. C. 1979. Flora Vitiensis nova: A where in Fiji. Para grass (Brachiaria mutica)is new flora of Fiji (spermatophytes only). dominant on a couple of beach terraces on Vol. 1. Pacific Tropical Botanical Garden, the south-central and southwestern portions La¯wa‘i, Kaua‘i, Hawai‘i. of the island and is outcompeting the herba- Thaman, B. 1998. Community utilisation and ceous outpost vegetation along beaches. Also valuation of mangrove resources in Fiji: of concern are the introduced mongoose Case studies of Sawa, Daku and Nadoria and the jungle mynah bird, which could lead Villages and Kinoya and Tamavua-i-wai to the collapse of populations of some native urban settlements, Viti Levu, Fiji. M.S. vertebrate and invertebrate animals. Con- thesis, James Cook University of North certed attempts should be made to eradicate Queensland, Townsville, Australia. or control these pest species so that they do Watling, D. 1982. Birds of Fiji, Tonga and not become ecologically dominant or destruc- Samoa. Millwood Press, Wellington, New tive on the island. Zealand. Nasoata Island, PABITRA Coastal Study Site in Fiji . Thaman et al. 203

Appendix Field Checklist of the Flora of Nasoata Island, Rewa Delta, Rewa Province, Viti Levu, Fiji Islands

Pteridophyta (Ferns and Fern Allies) Appendicula reflexa Bl. Aspleniaceae (Spleenwort Fern family) Grammatophyllum elegans Reichenb. f. Asplenium nidus L., bird’s-nest fern Oberonia heliophila Reichenb. f. Blechnaceae (Water Fern family) Taeniophyllum fasciola (Forst. f.) Seem. Stenochlaena palustris (Burm.) Beddome, swamp or Pandanaceae (Pandanus family) mangrove fern Pandanus tectorius Warb., pandanus, screw pine Davalliaceae (Hare’s-Foot Fern family) Poaceae or Graminae (Grass family) Davallia fejeensis Hooker, Fiji hare’s-foot fern *Arundo donax L., reed Davallia solida (Forst. f.) Swartz, hare’s-foot fern *Brachiaria mutica (Forsk.) Stapf, para grass, Nephrolepidaceae (Sword Fern family) Mauritius grass Nephrolepis biserrata (Sw.) Schott, fishtail fern Centotheca lappacea (L.) Desv. Nephrolepis hirsutula (Forst.) Presl., sword fern, *Ischaemum indicum (Houtt.) Merr., Batiki blue fishtail fern grass Polypodiaceae (Polypody Fern family) Lepturus repens (G. Forst.) R. Brown, beach Drynaria rigidula (Sw.) Bedd., basket fern bunch grass Phymatosorus grossus (Langsd. & Fisch.) Brownlie, **Oplismenus compositus (L.) Beauv., basket grass scented fern Miscanthus floridulus (Labill.) Warb., sword grass Pyrrosia lanceolata (L.) Farwell, lanceolate felt fern Paspalum vaginatum Sw., knot grass, salt grass, Psilotaceae (Psilotum family) swamp couch grass Psilotum nudum (L.) Beauv., psilotum, reed fern, Sporobolus cf. elongatus (Retz.) Beauv.?, wiregrass whisk fern Stenotaphrum micranthum (Desv.) Hubb. Pteridaceae (Brake Fern family) Thuarea involuta (Forst. f.) R. Br. ex R. & S. Acrosticum aureum L., swamp fern, mangrove fern Taccaceae (Polynesian Arrowroot family) Pteris tripartita Sw., lacy fern, sword brake *Tacca leontopetaloides (L.) O. Kuntze, Polynesian Vittariaceae (Tape Fern family) arrowroot Vaginularia angustissima (Brack.) Mett., grass fern Zingiberaceae (Ginger family) Vittaria elongata Swartz, tape fern *Zingiber zerumbet (L.) Sm., wild ginger Schizaeaceae Dicotyledonae (Dicots) Schizaea dichotoma (L.) Sm., branched comb ferm Anacardiaceae (Cashew or Rhus family) Angiospermae (Angiosperms) *Mangifera indica L., mango Monocotyledonae (Monocots) Annonnaceae (Custard Apple Family) Agavaceae (Century Plant family) **Annona glabra L., pond apple *Cordyline fruticosa (L.) A Chev., cordyline, ti Apiaceae (Parsley family) (Hawai‘i) *Centella asiatica (L.) Urban, Asiatic pennywort Araceae (Arum family) Apocynaceae (Dog-bane family) Epipremnum pinnatum (L.) Engl., taro vine Cerbera manghas L., cerbera Arecaceae or Palmae (Palm family) *Plumeria rubra L., frangipani, plumeria Cocos nucifera L., coconut palm Asclepiadaceae (Milkweed family) Commelinaceae (Spiderwort family) Hoya australis R. Br. ex Traill, wax vine **Commelina diffusa Burm. f., day flower Asteraceae (Sunflower family) Cymodoceaceae (Cymodocea family) **Mikania micrantha Kunth, mile-a-minute, mile- Halodule uninervis (Forssk.) Aschers, sea grass a-minute vine Halodule pinifolia (Miki) den Hartog, sea grass **Vernonia cinerea (L.) Less., iron weed Syringodium isoetifolium (Aschers.) Dandy, turtle *Wedelia trilobata (L.) Hitchc., wedelia, trailing grass daisy Cyperaceae (Sedge family) Wollastonia biflora (L.) DC., beach sunflower **Cyperus rotundus L., nut sedge, nut grass Barringtoniaceae (Barringtonia family) Cyperus stoloniferus Retz., beach sedge Barringtonia asiatica (L.) Kurz., fish-poison tree, Mariscus javanicus (Houtt.) Merr., marsh sedge barringtonia Scirpodendron ghaeri (Gaertn.) Merr. Barringtonia racemosa (L.) Spreng. Scleria polycarpa Boeck. Boraginaceae (Borage family) Dioscoreaceae (Yam family) Cordia subcordata Lam., sea trumpet, kou (Hawai‘i) *Dioscorea bulbifera L., bitter yam, air yam, aerial Tournefortia argentea L. f., beach heliotrope yam, air potato Caricaceae (Papaya family) Hydrocharitaceae *Carica papaya L., papaya, papaw Halophila ovalis (R. Br.) Hook f., salt-loving sea Clusiaceae or Guttiferae (Mangosteen family) grass Calophyllum inophyllum L., Alexandrian laurel, Orchidaceae (Orchid family) beach mahogany 204 PACIFIC SCIENCE . April 2005

Appendix (continued)

Combretaceae (Terminalia family) Lauraceae (Laurel family) Lumnitzera littorea ( Jack) Voigt, red-flowered Cassytha filiformis L., beach dodder, devil’s twine black mangrove Malvaceae (Mallow family) Terminalia catappa L., tropical almond, Malabar Hibiscus tiliaceus L., beach hibiscus, hibiscus tree almond **Sida rhombifolia L., broomweed, broom plant, Terminalia littoralis Seem., beach or coastal Cuba jute almond Thespesia populnea (L.) Sol. ex Correa, Thespians Convolvulaceae (Morning-Glory family) tree, milo (Hawai‘i and Polynesia) Ipomoea littoralis Bl., littoral morning-glory Melastomataceae (Melastoma family) Ipomoea macrantha R. & S., wild moon flower; **Clidemia hirta (L.) Don, Koster’s curse white morning-glory Meliaceae (Mahogany family) Ipomoea pes-caprae (L.) Sweet subsp. brasiliense (L.) Dysoxylum richii (A. Gray) C. DC., stinkwood v. Ooststr., beach morning-glory Xylocarpus granatum Koenig, puzzlenut Euphorbiaceae (Spurge family) Xylocarpus moluccensis (Lam.) M. Roemer, *Codiaeum variegatum (L.) Bl., croton puzzlenut Excoecaria agallocha L., blinding tree, poison Moraceae (Mulberry family) mangrove tree Ficus barclayana (Miq.) Summerhayes, Barclay’s Glochidion concolor Muell. Arg. fig Macaranga seemannii (Muell.-Arg.) Muell.-Arg., Ficus vitiensis Seem., Fiji fig macaranga Loganiaceae (Strychnine family) *Manihot esculenta Crantz, cassava, manioc, Geniostoma vitiense Gilg & Benedict tapioca Passifloraceae (Passion Flower family) Fabaceae (Pea family) *Passiflora laurifolia L., bell apple, laurel-leaved Caesalpinia bonduc Roxb., beach nicker, gray passionfruit nicker, nicker bean **Passiflora maliformis L., hard-shelled Canavalia cathartica Thou., Mauna Loa bean passionfruit (Hawai‘i) Piperaceae (Pepper family) Canavalia sericea A. Gray **Piper aduncum L., hooked pepper bush Canavalia rosea (Sw.) DC., sea bean Polygalaceae (Polygala family) Dalbergia candenatensis (Dennst.) Prain **Polygala paniculata L. *Derris malaccensis (Benth.) Prain, root, New Rhamnaceae (Buckthorn family) Guinea creeper Colubrina asiatica (L.) Brongn., soapbush, hoop Derris trifoliata Lour., derris vine, derris root withe **Desmodium heterophyllum (Willd.) DC. Smythea lanceata (Tul.) Summerhayes Entada phaseoloides (L.) Merr., vine, St. Thomas Rhizophoraceae (Mangrove family) bean Bruguiera gymnorrhiza (L.) Lam. f., black Erythrina variegata var. orientalis (L.) Merr., coral mangrove, oriental mangrove tree, dadap Rhizophora samoensis (Hochr.) Salvoza, mangrove Inocarpus fagifer (Parkinson) Fosb., Polynesian Rhizophora stylosa Griff., mangrove chestnut, Tahitian chestnut Rubiaceae (Coffee family) Intsia bijuga (Colebr.) O. Ktze., ipil tree Morinda citrifolia L., beach mulberry, Indian *Leucaena leucocephala (Lam.) de Wit, leucaena, mulberry lead tree, jumbie tree **Mitracarpus hirtus (L.) DC.? **Mimosa pudica L, sensitive plant, sensitive grass Tarenna sambucina (Forst. f.) Dur. ex Drake Pongamia pinnata (L.) Merr. Sterculiaceae (Cocoa family) *Samanea saman ( Jacq.) Merr., raintree, Heritiera littoralis Ait., looking-glass tree monkeypod Tiliaceae (Linden family) Vigna marina (Burm.) Merr., beach pea, beach **Triumfetta rhomboidea Jacq., Chinese burr bean, vigna Verbenaceae (Verbena family) Goodeniaceae (Naupaka family) Clerodendrum inerme L., beach privet Scaevola taccada (Gaertn.) Roxb, beach saltbush, **Lantana camara L. var. aculeata (L.) Mold., half-flower lantana Hernandiaceae (Hernandia family) Premna serratifolia L., premna Hernandia nymphaeifolia (Presl.) Kubr., lantern **Stachytarpheta urticaefolia Sims, blue rat tail, tree, hernandia false verbena Lamiaceae or Labiatae (Mint family) Vitex trifolia L. var. trifolia, blue vitex, beach **Hyptis pectinata (L.) Poit., mint weed, wild mint, vitex purple top

*, Species that are considered to be nonindigenous but of deliberate introduction by humans. **, Species that are assumed to be either accidental introductions or nonindigenous species that made it to the island naturally through either river or animal dispersal (e.g., bird or fruit bat).