LACUSTRINE, PROFUNDAL MEIOBENTHIC OLIGOCHAETES AS INDICATORS OF TROPHY AND ORGANIC LOADING

Meiobenthic and macrobenthic oligochaetes were collected from two dept hs in Lake Paijanne and examined together with environmental data in w hich two environmental gradients can be seen. Numbers of Piguetiella b lanci, Aeolosoma quaternarium and Aeolosoma hemprichi were,positively correlated with oxygen saturation and negatively correlated with total phosphorus and COD suggesting that these species are indicators of ol igotrophic conditions. Numbers of Amphichaeta leydigii, Specaria josin ae and Vejdovskyella comata were positively correlated with total phos phorus which implies that these species prefer eutrophic conditions. T he last three species and Dero digitata showed positive correlations w ith COD and organic sedimentation, which suggests that they also indic ate organic loading. A decrease in aeolosomatid biomass was seen with increasing phosphorus and organic loading. The average body size of de tritus-feeding naidids in the upper part of the profundal zone was red uced by organic loading, and more clearly eutrophication, which emphas izes the importance of including meiobenthic oligochaetes in pollution investigations. Of the naidid and aeolosomatid species, Chaetogaster langi preferred the greatest depths of the profundal zone while most o f the other species were more abundant at 20 m rather than at the maxi mum depth. Clustering of the oligochaete taxa supported these observat ions and clustering of sampling stations based on oligochaete variable s generally corresponded to clustering based on environmental data.