STRUCTURAL CHANGES WITHIN THE OLIGOCHAETA COMMUNITIES OF THE DANUBE DELTA IN RELATION WITH EUTROFICATION

摘要

During 1991-1994, the structure of the oligochaeta communities in eight representative Danube Delta lakes consisted in 2-3 dominant species, among which Potamothrix hammoniensis frequently comprised over 85%. The long-term trends in the dynamics of these communities are assessed on the basis of a comparative analysis of the total abundance and species dominance recorded for 1982, 1986 and 1992. During 1982-1994 comparable trends were noticed in all studied lakes. These consist in mass development firstly of ubiquitous L hoffmeisteri and, later one, of the P hammoniensis. The changes are linked with accelerated eutrophication.