SHORT COMMUNICATION
TAPROBANICA, ISSN 1800–427X. November, 2020. Vol. 09, No. 02: pp. 217–219, pl. 58–59. © Research Center for Climate Change and Department of Biology, Faculty of Mathematics & Natural Sciences, University of Indonesia, Depok 16424, INDONESIA. http://www.taprobanica.org/ https://doi.org/10.47605/tapro.v9i2.234
Range extension of a globally endangered Kalu Ganga, Sudu Ganga, Kambarawa Oya and Martenstyn’s barb, Systomus martenstyni its two tributaries, Theligam Oya and Puwakpitiya Oya at elevations 150–500 m a.s.l. (Goonatilake 2012; Goonatilake et al. 2020). All Sri Lanka is endowed with a rich network of of these streams drain the northern slopes of the rivers that dissects the island into 103 river Knuckles mountain range. More recently, basins. Mahaweli River, 332 km long, is the Rajakaruna et al. (2015) identified two more largest of these basins, covering 10,327 km2, populations of S. martenstyni from the lower approximately one-sixth of the island’s land reaches of Loggal Oya and Badulu Oya, which area. Mahaweli River passes through three are also two major tributaries of the Mahaweli bioclimatic zones and therefore comprises a River. Both of these rivers drain the cross-section of almost all the natural Southeastern basin of the Mahaweli River. ecosystems present in Sri Lanka other than A significant part of its habitat was to be tropical rainforest. Further, the river basin is affected by the construction of two large inhabited by a diverse species assemblage reservoirs, namely Moragahakanda and including a number of endemic plants, fish, Kaluganga on Amban River and Kalu Ganga frogs, reptiles and mammals that are restricted to that were commissioned in 2015. As a this river basin. Martenstyn’s Barb Systomus mitigation measure, IUCN Sri Lanka was given martenstyni (Sinhala name: Dumbara Pethia) is the task of translocating the population in the one such endemic freshwater fish species affected stretches of Amban River and Kalu restricted to the Mahaweli Basin. Ganga into safe sites in the upper catchment of Systomus martenstyni is endemic to Sri the two reservoirs (IUCN-SL 2012). During this Lanka and is listed as a globally and nationally period, spanning Jan 2012 to Dec 2013 endangered species (Fernando et al. 2019, altogether 484 individuals of S. martenstyni Goonatilake et al. 2020) due to habitat loss, were translocated to safe sites in the upper fragmentation, drought, and as it has a restricted catchment of Puwakpitiya Oya and Kalu rivers. distribution within the Mahaweli River Basin. During the translocation it became clear that the Systomus martenstyni can be easily population size of S. martenstyni is larger than distinguished from other species belonging to was assumed, even though the exact population genus Systomus by the presence of a prominent, size is not known at present. Further, during the elliptical black blotch on the caudal peduncle; last five years it has been recorded from a the body of the fish is golden in colour; all fins number of new localities (De Silva et. al. 2015, are deep red in colour and darker towards the Rajakaruna et al. 2015). Therefore the number ends; 27–30 + 2–3 scales along lateral line; 9–12 of known localities has increased its extent of (modally 11) pre dorsal scales; two pairs of occurrence (EOO = 2,410 km2) and area of barbels (Pethiyagoda 1991). Systomus occupancy (AOO = 156 km2) of the species. martenstyni was initially described as Puntius Here we report a new location of S. martenstyni by Pethiyagoda (1991) based on a martenstyni that was discovered while specimen collected from Pallegama at Kalu conducting a survey for another freshwater fish Ganga [not Kalu River], a tributary of Amban Labeo fisheri that is restricted to the Mahaweli River, which is one of the main tributaries of basin. In this study, identification was carried Mahaweli River. Pethiyagoda et al. (2012) out with the aid of the key characters introduced carried out a taxonomic revision of the genus by Pethiyagoda (1991). This species Puntius and referred this species to genus identification was done onsite based on the Systomus. Until 2015, the species was recorded following characters that are unique to S. only from tributaries of Amban River such as martenstyni: all fins are deep red in colour and
217 TAPROBANICA VOL. 09: NO. 02 KOTAGAMA ET AL. 2020 darker towards the ends; the body is a golden dandia, Tor khudree, Heteropneustes fossilis colour; and there is a prominent elliptical black and Poecilia reticulata. blotch on the caudal peduncle (Fig. 1). The fish The fact that this population was found was studied through visual observations from above the Victoria Dam means that the habitat the stream banks and by snorkeling in the deep available is highly restricted. The presence of sections of the streams. This new location is the dam also prevents the downward migration from the Hulu Ganga, another major tributary of of this fish and therefore the population can be Mahaweli River. Hulu Ganga is a southward considered to be an isolated sub-population. flowing river that originates from the southern Further, there are several mini-hydro projects slopes of Knuckles Mountain range and drains located in Hulu Ganga that result in further into the Victoria Reservoir. The new site is habitat fragmentation. Since the catchment of located close to Giddawa Village (Fig. 2), at an the Hulu Ganga does not contain any protected elevation of 560 m, which is the highest areas and most of the lands on the riverbank are elevation from which this fish has been recorded privately owned the chance of disturbance to the to date. All the previous records are confined to river is very high. Moreover, a number of illegal elevations 150–500 m a.s.l. The previous activities such as unsustainable fishing using elevation records from Badulu Oya and Loggl dynamite or poison and illegal sand mining were Oya were at 84–101 m a.s.l. Further, the new also observed in this river section during the locality is found at a point above the Victoria field investigation. Dynamite fishing or Dam. This new location is situated in the poisoning results in indiscriminate killing that intermediate zone of the island where the mean wipes out large numbers of fish, while sand temperature is ~25oC with a maximum mining causes extensive damage to riverbeds temperature ~29o–32oC. Annual rainfall received and alters the habitat characteristics. These by the Hulu Ganga catchment is around 1,375 threats may have a significant impact on this mm (MPE-SL 2009). small fragmented population that will heighten A population of around 15 to 20 individuals the risk of its extirpation from this site. was identified at the locality and the population Identification of overall distribution (Fig. 3) and was comprised completely of adult fish. The habitat characteristics of threatened endemic fish sections of the stream where the fish was species is a vital step that will facilitate proper observed had clear, well oxygenated water with assessment of the threat status as well as to a rocky or sandy substratum. The fish were develop sound recovery plans for such observed in both shady and open sections of the threatened endemic species. Therefore, river. However, the fish showed a preference for identification of this new location while rocky pools. The new location in which this improving the available data on this fish, also species has been identified had similar habitat highlights the need to take urgent conservation characteristics to other sites where the fish has action to protect this species as most of its been recorded. Shaded regions result from the habitats are under severe threat due to ongoing growth of tall trees on the riverbanks. The developmental activities as well as other illegal presence of rock outcrops in the riverbed leads activities. to the formation of rock pools, which have been described as the ideal and preferred habitat of Acknowledgements this fish by previous authors (Pethiyagoda 1991, We thank Ananda Mallawatantri (Country De Silva et. al. 2015, Rajakaruna et al. 2015). Representative, IUCN Sri Lanka) and Shamen The river section of the Hulu Ganga from which Vidanage (former Programme Coordinator, the fish was recorded was wide as in the case of IUCN) for their guidance and support during the previous known locations. A continuous and project. Darshani Wijesinghe (IUCN Sri Lanka) slow flow of water was observed but the water is acknowledged for preparation of maps and on the rock outcrops suggest that high flows related GIS. We also thank C. Sooriyabandara exist in this river during the monsoon season, (Director General) and L. Peries (former Asst. which was confirmed by local inhabitants. The Director Research) of the Department of other freshwater fish species recorded at the site Wildlife Conservation of Sri Lanka for include: Channa kelaartii, Dawkinsia providing permission for the survey. Finally, we filamantosa, Devario malabaricus, Garra thank the Asian Development Bank for ceylonensis, Puntius bimaculatus, Rasbora providing the financial support.
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RANGE EXTENSION OF A GLOBALLY ENDANGERED Systomus martenstyni
Literature cited MPE-SL (2009). Feasibility Study for Expansion De Silva, M.A., N. Hapuarachchi, and T. Jayaratne of Victoria Hydropower Station in Sri Lanka. (2015). Sri Lankan freshwater fishes. Wildlife Ministry of Power & Energy, Ceylon Conservation Society, Galle: 391pp. Electricity Board of Sri Lanka: 88 pp. Fernando, M., O.W. Kotagama, and S. de A. Pethiyagoda, R. (1991). Fresh water fishes of Sri Goonatilake (2019). Systomus martenstyni. Lanka. The Wildlife Heritage Trust of Sri The IUCN Red List of Threatened Species Lanka, Colombo: 362pp. 2019: e.T18908A150838910. doi:10.2305/ Pethiyagoda, R. M. Meegaskumbura, and K. IUCN.UK.2019-3.RLTS.T18908A150838910 Maduwage (2012). A synopsis of the South .en.
Published date: 28 November 2020
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