The distribution and ecology of the freshwater prawnCaridina singhalensis(Decapoda, Atyidae) endemic to Sri Lanka

Abstract

ABSTRACTThe distribution and microhabitat preference of the freshwater prawn,Caridina singhalensis, endemic to Sri Lanka, was determined. The species is now restricted to a 10–15 km stretch of the Behihul Oya headwaters, its distribution being determined by physiography and agricultural development.Beds ofIsolepis fluitanssupport some 76% of the adult population, at mean monthly densities of around 210 individuals m−2.Aponogeton jacobseniibeds and roots of marginal vegetation beneath overhanging banks support about 12% each, at mean monthly densities of 41 individuals m−2. The prawn produces young all year round but a peak in the number of ovigerous females occurs from September to January. Only juveniles produced after the rains appear to survive in great numbers. The submerged roots of marginal vegetation form a nursery area for about 45% of the annual output of young. Conservation plans for this endangered species need to take account of the particular importance ofI. fluitansand root habitats toC. singhalensis.