SOME ASPECTS OF ECOLOGY OF ENDEMIC FRESHWATER FISHES OF SRI LANKA

Upali S. Amarasinghe, R.R.A.R. Shirantha and M.J.S. Wijeyaratne

Department of Zoology, University of Kelaniya, Kelaniya 11600

Sri Lanka

Abstract of the Paper presented at the National Workshop on Conservation of Vertebrate Animals in Sri Lanka, 28 May 2004, Colombo, IUCN Sri Lanka and Ministry of Environment.

Sri Lanka supports a diverse freshwater fishes, about 48% of which are endemic. Most of these endemic freshwater fish species occur in the hill country forested streams of the wet zone of the country. There are sophisticated interactions between fish species in a fish community and its environment for food, space and/or spawning. Also as evident from the biology of cyprinids in hill streams in Sri Lanka, most of the endemic frshwater fish species species in Sri Lanka tend to show well-defined niche segregation and ecological adaptations. Any direct human influenece that works on this web of inter-relationships or through large disturbances such as erosion, pollution or climatic factors, are therefore likely to have far-reaching and largely unpredictable effects. However, several anthropogenic activites such as deforestation, gem mining and uncontrolled use of agrochemicals, pose significant threats to survival of many endemic freshwater fish species in Sri Lanka. Exploitation of endemic fish species from the wild for ornamental fish trade is also a major cause of decline of their populations. Further, accidental introduction of clown knife fish (Chitala ornatus) and cleaner fish (Ptrygoplichthys multiradiatus), which poses threats to biodiversity of freshwater fishes in Sri Lanka, is an indirect adverse effect of ornamental fish trade. Althogh some introductions of exotic fish species such as African cichlids, most notably Oreochromis mossambicus and O. niloticus, have socio-economic benefits and do not pose any significant threats to frehwater fish biodiversity in Sri Lanka, effective strategies should be implemented to control transfer and introduction of aquatic organisms. Scanty and incomplete information on the ecology of endemic freshwater fish species is of little use for revising legal framework pertaining to their conservation and to support the decision making process in the approval of development project proposals. An effective means for rapid assessment of conservation status is therefore necessary for the endemic freshwater fish species in Sri Lanka.