Differences in occurrence in relation to the eutrophication level among chironomid species of the genus, Tanytarsus, in littorals of lakes

Occurrences in relation to the eutrophication level were investigated of chironomid species of the genus Tanytarsus by the method of identifying male adults emerging from the materials attaching to concrete plates submerged on the bottom at littorals of some lakes at different eutrophication levels in Japan. As a result, the occurrence patterns of nine species were clarified. Among these, T. tamagotoi occurred in the largest number in waters at a low eutrophication level whereas T. takahashii occurred in the largest number at a middle eutrophication level, although they occurred at all levels. On the other hand, T. unagiseptimus and T. oyamai occurred in the largest numbers at a high level. These results suggest that species compositions of this genus in littoral communities can be applied to biological judgement of the eutrophication levels of lakes.