Freshwater Fish Survey of Homadola-Nakiyadeniya Estates, Sri Lanka
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FRESHWATER FISH SURVEY OF HOMADOLA-NAKIYADENIYA ESTATES, SRI LANKA. Prepared by Hiranya Sudasinghe BSc. (Hons) Zoology, M.Phil. reading (University of Peradeniya) INTRODUCTION The diversity of freshwater fishes in Sri Lanka is remarkably high, with a total of 93 indigenous fishes being recorded from inland waters, out of which 53 are considered to be endemic (MOE, 2012; Batuwita et al., 2013). Out of these, 21 are listed as Critically Endangered, 19 as Endangered and five as Vulnerable in the National Red List (MOE, 2012). In addition, several new species of freshwater fishes have been discovered in the recent past which have not yet been evaluated for Red Listing (Batuwita et al., 2017; Sudasinghe 2017; Sudasinghe & Meegaskumbura, 2016; Sudasinghe et al., 2016). Out of the 22 families that represent the Sri Lankan freshwater ichthyofauna, the family Cyprinidae dominates, representing about 50% of the species, followed by the families Gobiidae, Channidae and Bagridae, which represent seven, five and four species, respectively. The remainder of the other families are each represented in Sri Lanka by three species or less. Four major ichthyological zones, viz. Southwestern zone, Mahaweli zone, Dry zone and the Transition zone were identified by Senanayake and Moyle (1982) based on the distribution and the endemism of the fish. The Southwestern zone shows the greatest diversity, followed by the Mahaweli zone, with the least diversity observed in the Dry zone. About 60% of the freshwater fishes occur both in the dry and the wet zones of the island while the rest are more or less restricted to the wet zone. Of the endemic fishes, more than 60% are restricted to the wet zone of the island while about 30% occur in both the dry and the wet zones. Thirteen species are considered to be micro-endemics, with highly restricted distributions within the island. As part of my ongoing research, I first visited the Homadola estate on 26/Sep/2017 to sample a recently described species: Devario udenii. Upon my first visit, I was invited to carry out an extensive study on the freshwater fish fauna to facilitate the ongoing RSPO projects being carried out in these estates. Thus, herewith I provide the information gathered during my brief field sampling and recommendations to enrich the freshwater habitats inside these estates. 1 MATERIALS AND METHODS Field work was carried out on 26/Sep/2017 and 15-17/Dec/2017 in aquatic habitats inside the Homadola and Nakiyadeniya estates belonging to the Watawala Plantations PLC. Habitat characteristics of the sampled sites are provided in Table 1. Sampling sites were selected to represent a variety of different habitat characteristics (Appendix 1). Garmin® Map GPS 64 was used to obtain GPS coordinates of the locations. Fishes were observed underwater using a mask and a snorkel where applicable and netting was done either using a drag net (3 m × 1.5 m) and hand net (0.5 m ×0.5m). Fishes were photographed underwater using Olympus TG4 camera and some were captured and photographed in a glass aquarium using a Canon 7D camera with a 100 mm macro lens. Table 1. Sampling localities and habitat characteristics of sites at Homadola and Nakiyadeniya estates Habitat A B C D E F Local name Homadola Homadola Homadola Madola, Nakiyadeniya Seethala dola, estate estate estate Homadola estate estate Nakiyadeniya estate GPS 6.2137, 6.21576, 6.22542, 6.22953, 6.16996, 6.15178, coordinates 80.34956 80.34361 80.33901 80.36664 80.35834 80.31023 Habitat type Large stream Large stream Small river Small river Small streams stream Surrounding Disturbed Disturbed Disturbed Undisturbed Anthropogenic Palm oil secondary secondary secondary secondary forest /palm oil forest forest/ palm forest/tea oil Flow rate Fast Moderate Moderate/Fast Moderate/Fast slow Moderate/ Fast Bottom Pebbles/sand Pebbles/sand Pebbles/sand/ Boulders/pebbles Sand/silt Pebbles/sand/ substrate /boulders boulders boulders Canopy 50-70% 50-60% 50-60% 50-70% open 20-30% cover 2 RESULTS A total of 29 species of freshwater fishes belonging to 12 families were recorded during the survey (Table 2). Family Cyprinidae dominated with 15 species followed by family Gobiidae (three species) and Osphronemidae (two species). The rest of the families Cobitidae, Nemacheilidae, Bagridae, Claridae, Belonidae, Aplocheilidae, Channidae, Mastacembelidae and Poecilidae were represented by a single species each (Figure 1). Out of the 29 species recorded, 16 species were endemic. The freshwater fish species recorded included a Critically Endangered species (Sicyopterus griseus), eight Endangered species (Pethia cumingii, Pethia nigrofasciata, Puntius kelumi, Puntius titteya, Systomus pleurotaenia, Mystus ankutta, Aplocheilus werneri, and Sicyopus jonklaasi), a Vulnerbale species (Garra ceylonensis) and an exotic species (Poecilia reticulata: Figure 2). In terms of species richness, the most number of species were recorded at Habitat C (19 species) and the least number of species were recorded at Habitat B (4 species: Figure 3). Figure 1. Freshwater fish families recorded during the fish survey. 3 Table 2. List of freshwater fish species recorded in the streams of Homadola and Nakiyadeniya estates during the survey. Species in bold-face are endemic. Family Species Common Name Habitat Conservation Status A B C D E F Cyprinidae Dawkinsia singhala Sri Lanka - - + + + - Least Concerned Filamented barb Cyprinidae Devario udenii Udenii’s Danio + + + + - - Not Evaluated Cyprinidae Garra ceylonensis Sri Lanka Stone + - + + - + Vulnerable Sucker Cyprinidae Pethia cumingii Cuming’s Barb - - + - - - Endangered Cyprinidae Pethia nigrofasciata Black Ruby Barb - - + + - - Endangered Cyprinidae Puntius bimaculatus Red-side barb - - - - + - Least Concerned Cyprinidae Puntius dorsalis Long-snouted + + + + + - Least Concerned barb Cyprinidae Puntius kelumi Kelumi’s barb - - + + - - Endangered Cyprinidae Puntius titteya Cherry barb - - - - + + Endangered Cyprinidae Puntius vittatus Silver barb - - - - + + Least Concerned Cyprinidae Rasbora dandia Broad-lined - + + + + + Least Concerned rasbora Cyprinidae Rasboroides Golden rasbora - - - + - - Not Evaluated pallidus Cyprinidae Systomus Black-lined barb + + + + - - Endangered pleurotaenia Cyprinidae Systomus sarana Olive barb - - + - - - Least Concerned 4 Cyprinidae Tor khudree Mahseer + - + + - - Near Threatened Cobitidae Lepidocephalichthys Common spiny - - - - + - Least Concerned thermalis loach Nemacheilidae Schistura Banded mountain + - + + - + Near Threatened notostigma loach Bagridae Mystus ankutta Dwarf catfish - - + - - - Endangered Claridae Clarias brachysoma Walking catfish - - - - + - Near Threatened Belonidae Xenentodon cancila Freshwater gar - - + - - - Near Threatened fish Aplocheilidae Aplocheilus werneri Werner’s killifish - - - - + + Endangered Gobiidae Awaous Scribbled goby + - + + - + Least Concerned melanocephalus Gobiidae Sicyopterus griseus Stone goby - - + - - - Critically Endangered Gobiidae Sicyopus jonklaasi Lipstick goby + - + + - - Endangered Osphronemidae Belontia signata Combtail + - + + + + Near Threatened Osphronemidae Pseudosphromenus Spike-tailed - - - - + - Least Concerned cupanus paradise fish Channidae Channa gachua Brown snakehead - - - - + - Least Concerned Mastacembelidae Mastacembelus Marbled spiny eel - - + + - - Least Concerned armatus Poecilidae Poecilia reticulata Guppy - - - - + - Exotic 5 Figure 2. Conservation status of freshwater fish species recorded during the survey. Figure 3. Species richness in different sampling localities during the survey. 6 DISCUSSION Recording of 29 species of freshwater fish species based on the brief survey carried out during only four days of field work, suggest that the aquatic habitats are quite diverse and rich in terms of freshwater fishes. Though not recorded from this survey, there are several other confirmed records of some freshwater fish species in the collection of the Wildlife Heritage trust (WHT) now at the National Museum of Sri Lanka recorded from this area. This include a Critically Endangered species called Lepidocephalycthys jonklaasi (Jonklas’s loach) recorded from “Udugama ela” (Figure 4). This species is likely recorded around the Habitat C in small shady streams flowing to the site that I sampled. Thus, close inspection in small streams around habitat C is highly recommended to confirm the presence of this species. Lepidocephalycthys jonklaasi is recorded only in few localities in the lowland wet zone mainly around rainforests and prefers slow flowing, well shaded, small streams with clear water. Thus, if this species is recorded from the small streams inside the Homadola estates, an in- situ conservation plan can be initiated inside the estate. Figure 4. WHT30661, A specimen of Lepidocephalycthys jonklaasi collected from “Udugama ela” in 2000. Other freshwater fish species not recorded during my brief survey but are known to occur around Homadola area include Channa orientalis (Smooth breasted Snakehead: Endemic, Vulnerable), Ompok argestes (Mottled Butter catfish: Endemic, Not evaluated) and Heteropneustes fossilis (Stinging Catfish: Native, Least Concerned). If these species are also taken into account, the total number of species recorded around Homadola-Nakiyadeniya sites would be 33 species of which 19 would be endemic. If more number of sampling 7 localities and night sampling were carried out, it is likely that several more species of freshwater fish are to be recorded from Homadola-Nakiyadeniya estates. When comparing the species richness and endemicity