Water environment and species composition of profundal oligochaetes in dam lakes of Japan.

Abstract

Water environment and species composition of profundal oligochaetes were studied for 48 dam lakes in Japan, by analyzing published data and scrutinizing voucher specimens, respectively. Among 11 environmental parameters in the surface water of the present dam lakes, total phosphorus was the most frequently correlated with other parameters. Modified Carlsonʼs trophic state index based on Secchi disk transparency ranged from 31 to 70 among the present dam lakes, corresponding to meso- to eutrophic lakes. There is no significant relationship between abundance of profundal zoobenthos and water depth nor trophic conditions of dam lakes. Oligochaetes surpassed others among profundal macrozoobenthos in the present dam lakes. Sixteen species of oligochaetes were recorded in the 43 dam lakes studied, of which two tubificines, Limnodrilus hoffmeisteri and Tubifex tubifex were the commonest and widespread regardless of geographical location. The composition and abundance of oligochaete community were not largely different from those in deep, meso- and eutrophic natural lakes in Japan.