Benthic macroinvertebrates and their distributions of Hazar lake littoral region

This study has been carried out in Hazar Lake which is tectonic, deep and alkali lake and located within the city borders of Elazig between October 2007-September 2008, to determine the Hazar Lake littoral region benthic macroinvertebrates and their distributions, for this purpose 9 samples were taken from 21 stations inside 8 sampling area spesificied inside the littoral region of the lake.In order to determine the similarities between the sampling points and the sampling periods, based on the taxon abundance, Cluster Analysis has been conducted in accordance with Sorensen?s similarity index. Moreover, PCA (Principal Component Analysis) has been used to summarize the composition of benthic macroinvertebrate fauna.According to this, it has been detected that benthic macroinvertebrate community in the littoral region of 0-15 m depth has been composed of 22 taxa which belong to 9 classes as Clitellata, Insecta, Arachnida, Malacostraca, Ostracoda, Branchiopoda, Entognatha, Maxillopoda, and Turbellaria. 58.9% of total 28.342 organisms were Tubificidae, 30.6% of the total was Chironomidae, and the remaining 10.5% were taxa belonged to other families. Average abundance in the lake was 1.253 individual/m2, average species diversity was 0.90, summer has got the highest average number of organisms and winter has got the lowest average number of organisms. Furthermore, the detected taxa have been classified according to their tolerance against organic pollution. According to this, the taxa with medium level tolerance for organic pollution have been recorded to be 64.0%, tolerant taxa have been 29.6%, and intolerant taxa have been 6.4%.It has been determined that the physical factors such as depth and the changing ground structure depending on the depth have been the most important factors on the distribution of Hazar Lake littoral region benthic macroinvertebrate. Water quality variables have got secondary importance. The changes in depth and ground structure factors have also been effective on the taxa richness and diversity, water temperature was the most important environmental factor on seasonal change, however biological characteristics of benthic macroinvertebrate and feeding relationships between other organisms living in the lake in generally have been ecological factors which could not be neglected. Systematically family level has got high richness whereas genus level has got low richness. Finally, dissolved ion content at high levels when compared to many other lakes and pH value and the organisms? adaptation abilities to these variables have caused these results to emerge.Based on the data obtained from the research region of Hazar Lake, it is concluded that its trophic level can be evaluated as intermediate class of oligo-mezotroph.