摘要：A 300-year sediment record was used to investigate cladoceran community and phenotypic responses under extreme eutrophication process in the clay-turbid Mallusjärvi, a lake in southern Finland. The aims were to identify reference and disturbed communities, and to assess species and functional diversity and phenotypic characteristics as indices for lake ecological quality. The results showed that the oligomesotrophic reference status is characterized by rich planktonic and littoral-benthic assemblages with high species and functional diversity. Nutrient-enrichment, caused by increased agricultural activities in the catchment, was enhanced during the 19th century, inducing gradual responses in cladoceran community composition (decreasing benthic and increasing planktonic taxa) and functioning (decreasing invertebrate and increasing fish predation, decreasing species and functional diversity), and changes in phenotypic properties (decreasing body size of Bosmina longirostris and relative ephippial production). The disturbed state was characterized by eutrophic-hypereutrophic conditions and subsequent high abundance of planktonic cladocerans and deteriorated littoral-benthic conditions. Our results suggest that cladoceran communities, and their functional and phenotypic indices, are sensitive indicators of long term limnological deterioration and ecosystem equilibrium.
