Macrobenthic community structure in a polluted lake: Lake Nemi (Central Italy)

Abstract

Abstract A study was made from February 1976 to December 1978 on the macrobenthic fauna of Lake Nemi, subjected in the last few years to a rapid deterioration in its water quality. In all, 21 taxa were found at depths from 5 to 31 m in four sites of the lake, three of which directly received domestic discharges from the villages of Genzano and Nemi and from the nursing-home “Villa delle Querce”. Oligochaeta (1 species of Naididae and 6 of Tubificidae), and Chironomidae (10 genera) were the major groups, in both density and biomass, of littoral and profundal fauna. Few other taxa were present. The qualitative composition of benthic community, the high percentages of tubificids and low densities of chironomids (especially from 10 to 31 m), together with the marked numerical reduction of the whole benthic fauna with increase in depth, were all typical features of a highly eutrophicated lake with oxygen deficit in the profundal area during most of the year.