Ichthyofauna of Tripa Peat Swamp Forest , Aceh province , Indonesia

The Tripa Peat Swamp Forest (TPSF) suffers from deforestation due to agriculture, this habitat degradation potentially has a negative impact on fish biodiversity and community assemblages. The objective of this study was to develop an inventory of the fish fauna, evaluate the spatial variation in assemblage structure, document alien species, and quantify the economic value of fish species found from the area. Fish assemblages from the main rivers and tributaries of TPSF were sampled on May to June 2013. A total of 764 individuals were sampled during the survey, constituting 34 families, 47 genera, and 73 species where 46 species are categorized as fish consumption, 17 have potential for aquaculture, and 10 species have potential for ornamental, and three are non native. Cyprinidae is the predominant fish family within the TPSF. Fish assemblages were generally characterized by small population size for each species and low similarity among sites, reflecting the distinctive nature of each sampling site.


INTRODUCTION
Indonesia is recognized as a country of "mega biodiversity" second in fish species richness only to Brazil (Muchlisin and Siti-Azzizah 2009).Djajadiredja (1977) estimated there being 4,000 fish species in Indonesian waters, a large proportion of which occurring in freshwater.Suwelo (2004) reported that there are at least 1,000 species of freshwater fishes found in Indonesian waters, Kottelat et al. (1993) estimated more than 964 species of freshwater and brackish water fishes in western Indonesia and Sulawesi, and about 114 species of fish had been recorded from Aceh, northern Sumatra (Muchlisin and Siti-Azizah 2009).Kottelat and Whitten (1996) estimated that approximately 400-600 species of fishes from Indonesian waters have yet to be described and a greater research effort was needed, especially in hitherto unsurveyed habitats such as peat swamps.
Peat swamps are aquatic habitats overlaying and draining areas dominated by peat soils, formed from historical forest litter deposition.They are hydrologically important water storages in the landscape and important habitat for a range of fauna including fish.The soil of peat swamps has high organic matter content and varies in thickness from less than 0.5 m to a depth of more than 20 m (Wahyunto et al. 2005).Tropical peat swamps typically contain a high biodiversity of plants and animals.There are approximately 20.6 million ha of peat swamp forests in Indonesia, and approximately 35% are found in Sumatra, 32% in Kalimantan and 30% in Papua Islands.Approximately a quarter of Indonesian peat swamp forests have been deforested and converted to palm oil plantations and other agricultural activities (Task Force REDD 2012), potentially degrading the flora and fauna of this ecosystem, including the fish communities.
Aceh province, northern Sumatra has two significant peat swamp forest ecosystems: Tripa and Singkil peat swamps.To date, no information on the fish biodiversity from these areas is available, yet the deforestation of peat swamp forests in Aceh, especially Tripa, continues unabated.The Tripa peat swamp forest ecosystem originally covered approximately 61,000 ha and by 2007 approximately 49% had been deforested and converted to palm oil plantations, and a further 27% had been cleared one year later (PIU-SERT 2013).Impact assessment of this change on the aquatic component in this forest is hampered by lack of pre impact data, but it is known that conversion of forests to palm oil plantations has caused an increase in the incidence and severity of forest fires in the drought season and floods in the rainy season (unpublished data).Forest conversion in this area has had minor positive economic benefit for local communities (Wahyunto et al. 2005).In contrast, the increased incidence of natural disasters, for example, the increased frequency and severity of floods during the last decade, has had negative local economic effect.
There are four main rivers flowing across the Tripa peat swamp ecosystem, the Tripa, Seumanyam, Seuneam and Batee Rivers.In addition to the influence of these rivers, this ecosystem is bordered and affected by the tidal regime of the adjacent Indian Ocean.Consequently, the aquatic habitats of the Tripa system are highly dynamic.According to YLI-AFEP during both day and night at every location being sampled over a period of one or two days.

Preservation and identification
Collected fish were placed in 10% formalin and curated at the Laboratory of Ichthyology, Faculty of Marine and Fisheries Syiah, Kuala University, Banda Aceh, Indonesia.Species were identified using Kottelat et al. (1993), Saanin (1968) and Froese and Pauly (2014).

Analysis
The frequency of incidence (FOI) of each species was estimated according to Muchlisin and Siti-Azizah (2009) as follows: Where, N i .St= total nuber of locations where the species i where found, N.St= total number of sampling locations.Remaining biological indices were estimated using routines available within the software package Plymouth Routines in Multivariate Ecological Research (Primer E) version 6. Margalef's species richness index (d) was estimated according to the formula (Mugurran 1998) as follows: Where, d = species richness, s = total species, N = total individual of all species.
According to Magurran (1988), d value less than 3.5 (2008) the TPSF provides habitat for a range of vertebrates of high conservation significance including the Orangutan (Pongo abelii), Mentok Rimba or White-winged Duck (Cairina scutulata), Sumatran Tiger (Panthera tigris sumatrensis), Estuary Crocodile (Crocodilus porosus), Honey Bear (Helarctos malayanus) and Rangkong or Hornbill (Buceros spp.).However, there exists little information on the fish fauna in Tripa peat swamp forest; an information gap crucially important in the formation of better conservation strategies for the aquatic ecosystem of the Tripa peat swamp.Hence, the objective of the present study was to establish an inventory of the fish fauna of the Tripa Peat Swamp Forest and evaluate economic and conservation significance of the fish fauna.

MATERIALS AND METHODS Location and sampling
The Tripa peat swamp forest is situated in Nagan Raya and Aceh Barat Daya districts at coordinates 03°44′-03°56′ N and 096°23′-096°46′ E. The study was conducted between May and June 2013 at twelve sampling locations in Tripa peat swamp (Figure 1).Sample locations were chosen to cover a wide array of estuarine, riverine and tributary habitats.Typical habitats of sampled sites are shown in Table 1 and Figure 2. Fish assemblages were sampled using a variety of methods including cast nets, gillnets, handnets (all with various mesh sizes: 0.5, 1.0, and 1.5 inches) and hook and line.Sampling occurred indicates low species richness, value between 3.5-5.0indicates moderate species richness, and value higher than 5 indicates high specie richness.
The Shannon Winner diversity index was calculated as follows: H = -ΣPi LnPi Where, H = Shannon Winner diversity index, P i = N i /N, (N i = total number of individual of species i, N = total number of individual of all species. The diversity index expresses the species richness in a community and shows the balance in individual proportion of every species.According to Odum and Barret (2004) the Shannon Winner diversity index is classified into three levels, low (H<2), moderate (2<H<4), and high (H>4).
The Simpson dominance index (D) was calculated as follows: Where N i = total number of individuals of species i, N = total number of individuals of all species, and S= total number of species.These values are ranged between 0 and 1with values near 0 (lower) indicate no species was numerically dominant, while values tend to 1 (higher) indicate that the fish community was dominated by few species.
Presence or absence of data species for each site was used to construct a site by site similarity matrix based on the Bray Curtis similarity distance.This matrix was then used to generate a dendogram of site similarities based on the UPGMA routine available within Primer-E.Version 1.2 (Clarke and Warwick 2001;Clarke and Gorley 2005).Before calculating the Bray-Curtis similarity coefficient, the standardised data was root transformed.This has the effect of scaling down the importance of abundant species (Clarke and Warwick 2001).

Introduced and economic status of fishes
The indigenous status of each fish was determined based on the Global Invasive Species Database (http://www.issg.org/

No
Sampling location Coordinates Characteristic of location 1.
Tripa River mouth 03°51′02.6″N, 096°23′10″ E River mouth with brackish water characteristic.The location was flooded regularly during rainy season.There is a traditional fish landing near to sampling location.

3.
Seuneuam River mouth 03°55′47.9″N, 096°27′40″ E River mouth closed by sand bar and it has brackish water characteristic.The sand bar would be broken during rainy season and the river mouth was closed at the time of sampling.

4.
Pulo Ie Canals 03°47′05″ N, 096°28′20.9″E This location is the creek of Seuneuam River with freshwater characteristic.There is a palm oil processing plant near to location.Strong suspicion that the waste discharged into the canal and creeks indicated by physical condition of water (coagulants suspended).

5.
Batee River mouth 03°45′56.9″N, 096°28′47.6″E The mouth of Batee River with brackish water characteristic and strong affected by tides, It is covered by mangrove at some parts.

Alue
The economic status of fish species was assessed with regard to its potential as a fish target for aquaculture whether as food fish or as an ornamental species based on Muchlisin (2013a).

Abundance and distribution
A total of 764 individuals representing 34 families, 47 genera and 73 species were sampled during the study.Of the 73 species, 32 were restricted to freshwater, 37 restricted to brackish water and 5 occurred in both fresh and brackish waters (Table 2).The Tripa River mouth (site A) has higher number of species, while Pulo ie canals, Matee river and Lamie river have lower number of species richness (Table 2).The largest number of individuals were recorded from the mouth of the Tripa River (site A), and a lower number was recorded at Ranto Kepala Gajah Canals (site I) (Table 3).

Economic status and alien species
The economic status for each species was based on local market consumption or potential value in the ornamental

DISCUSSION
Cyprinidae is the largest group of freshwater fishes in the world and was the dominant family recorded from the Tripa peat swamp, Aceh province, Indonesia.Cyprinidae is similarly dominant in many other freshwater habitats throughout Asia, for example Muara Enim, Southern Sumatra Indonesia (Junaidi 2004), Pahang River System, Malaysia (Miyazaki et al. 2013) and the Yangtze River in China (Fu et al. 2003).Among the freshwater fishes, Puntius brevis and Osteochilus vittatus were commonly found at most sites.Chelonodon patoca and Lutjanus argentimaculatus were commonly found in brackish water of river mouths.This is in agreement to Simanjuntak et al. (2011) who reported that C. patoca and L. argentimaculatus occupy coastal habitats with sandy and muddy water bottoms and can be found at the river mouth or estuary areas as recoded in this study.
According to Muchlisin and Siti-Azizah (2009), there are at least four species of catfish (Clarias teijsmanni, C. nieuhofii, C. batrachus, and C. gariepinus) and three species of mahseer (Tor tambra, T. soro and T. tambroides) found in Aceh.However, only one species of catfish and mahseer were sampled from the TPSF during the study.The total number of catfish and mahseer in Tripa peat swamp waters is probably higher than recorded in this study and further sampling using a greater diversity of sampling gears and sampling duration would be needed to detect them.
We recorded three species of alien fishes in Tripa peat swamp; Trichopodus pectoralis or known as Siamese gourami has been present in Indonesia waters for an extended period   The negative impact of alien fish species on indigenous fish communities include predation on local fishes (Nicola et al. 1996), competition for food and habitat (Alcaraz and Garcia-Bethou 2007), interference with mate selection (Seehausen et al. 1997), and unexpected cross breeding with local fish resulting in depressed genetic diversity and distinctiveness of local fishes and the transmission of disease (Almodovar et al. 2006).However, the total number of alien fish species in the TPSF is lower than that recorded in other regions of Aceh province.At least six introduced fish species were recorded in Lake Laut Tawar, Takengon, and five species of alien fish species occur in the irrigation canals and paddy fields of Sibreh, Aceh Besar (Muchlisin 2012).
There are at least 40 species of freshwater fishes in Aceh waters known to be of economic value; either as species valuable for human consumption or as aquarium fishes (Muchlisin 2013a).Of the 73 species recorded in this study, 46 species have value for human consumption; of these, 17 species have potential for aquaculture, and 10 species are potential in the aquarium trade.The experimental cultures of indigenous freshwater fish species in Aceh province, Indonesia has been started for T. tambra (Muchlisin, 2013b), Osteochilus vittatus (Muchlisin et al. 2014) and A. testudineus, some studies are initially conducted for these species, but other potential species as recorded in this survey need more attention to be studied prior to be commercially cultured.
The catfish (C.batrachus) and Acehnese mahseer (T.tambra) (locally know as sengko and keureling, respectively) are two species favored and targeted by local fishermen.Only one individual of T. tambra and four individuals of C. batrachus were recorded during the survey.Populations of these species in the wild have apparently decreased significantly in recent years.According to local fishermen, the reduction in catfish catches over the last two decades is about 80%.In the 1970s, catches of this species with a bubu (a local traditional trap) weighed 5-10 kg.Current catches of catfish have decreased to less than 1 kg (personal communication by senior author with local fishermen).We believe that similar reductions in abundance and population structure are also occurring for other fish species of Tripa peat swamp.The high value of fishes recorded from the Tripa peat swamp system strongly suggests that this system contains biological resources of high economic potential and value, in addition to their intrinsic biological value.Depletion in abundance and species richness of catfish in Tripa peat swamp waters is closely associated with devastation of Tripa peat forests, which has degraded and reduced catfish habitat (i.e.previously perennial habitats now dry out during the dry season).Only approximately 12,000 ha (less than 20% of original extent) of Tripa peast swamp forest currently remains in good conditions.

Figure 1 .
Figure 1.Map of the Tripa Peat Swamp Forest in Nagarn Raya and Aceh Barat Daya, Indonesia showed sampling sites (green circles).

Figure 3 .
Figure 3. Composition of fish families in Tripa peat swamp to species members.

Figure 4 .
Figure 4.The similarity distance of fish community structure among locations in Tripa peat swamp .

Table 1 .
Study location, GPS coordinates and characteristics of each sampling location.

Table 3 .
(Muchlisin 2012), species and biological indices of Tripa peat swamp forest fishes assemblages.-adaptedtothis region.It believed that this species is originated from Mekong basin and introduced to Indonesia on 1934.Oreochromis niloticus was introduced into Indonesia by the Center of Research and Development for Freshwater Aquaculture, Marine and Fisheries Affairs of Republic Indonesia in 1969.It is estimated that these species became established in Aceh province in the 1990s(Muchlisin 2012), this is the first recording of these species from the TPSF.Pterygoplichthys pardalis was first observed in 2007 in Alue Sapek waters (personal communication, local fishermen of Alue Sapek village, Suka Makmur District).This species is an aquarium fish, but frequently released into open waters when it achieves large size and is no longer attractive as an ornamental fish.Public awareness campaigns are required to prevent this from continuing to occur in the future.