Oligochaete communities at the mouth of the Neva and their relationship to anthropogenic impact

Changes in the oligochaete community of the Neva Mouth for the period 1982–1993 are discussed in relation to anthropogenic impacts. A number of community parameters such as species composition, biomass and diversity were generally stable, although local changes were noted. Predominance of eutrophic species, i.e. L. hoffmeisteri, T. tubifex, P. hammoniensis was enhanced, whereas mesotrophic and oligotrophic species — L. isoporus, S. heringianus, T. newaensis disappeared or became less numerous at some stations. The reverse trend was observed at other stations. These phenomena were accompanied by a sharp increase in the variability of biomass and/or diversity, which is regarded as exceeding normal annual fluctuations. The oligochaete community is recognized as a promising indicator of the ecological situation in the Neva Mouth.