Effects of long-term non-point eutrophication on the abundance and biomass of macrozoobenthos in small lakes of Estonia

Abstract

The effects of eutrophication on macrozoobenthos were studied in small Estonian lakes. Altogether, 380 sites of 107 lakes sampled repeatedly before and during/after significant non-point eutrophication were compared. The data of 1951–1967 were considered the reference samples, and the data of 1972–1995 were used as the test samples. A total of 66 macro- and megazoobenthic variables were studied. The individual weight of chironomid larvae, as well as the abundance and biomass of several animal groups, had changed significantly between the two periods. The possible reasons for the changes are briefly discussed. Key