An investigation on phytoplankton and its seasonal variation of Dodurga Dam Lake (Boyabat, Sinop)

The phytoplankton, biomass, seasonal variation and some of physicochemical parameters which affect that change is investigated between August 2010 and July 2011 in Dodurga Dame Lake (Boyabat, Sinop). A total of 35 taxa belong to Charophyta, Chlorophyta, Cyanophyta, Dinoflagellata, Euglenozoa, and Ochrophyta were identified in the phytoplankton. Identified 35 taxa are respectly, 6 Charophyta, 13 Chlorophyta, 1 Cyanophyta, 4 Dinoflagellata, 3 Euglenozoa and 8 Ochrophyta belong to these division. It has been given as new record for 5 of these taxa in Turkey of algal flora.In this study, according to Water Pollution Control Regulation and test result of water analyses indicated that the average temperature, pH, dissolved oxygen and nitrate values represent class I and refers high-quality waters, the average nitrite values represent class II and refers less polluted waters.On phytoplankton data obtained from the surface stations and the depths of the first station were applied the Simpson's Diversity index, Shannon-Wiener Diversity indices and the results showed that lake water into the group of partly contaminated areas. Cluster analysis applied of surface stations and were determined 4 groups (A, B, C, D) at 40% similarity and were determined 6 groups (A, B, C, D, E, F, G) at the depths of the first station. According to ANOSIM, the differences were identified between groups and SIMPER, species that contribute to intra-group similarity were identified.Due to morphometric structure and the level of water is deep in Dodurga Dam Lake that according to phosphorus and chlorophyll-a values, it has oligotrophic character. This character, according to phytoplankton reproduction, in spring and summer months shows oligotrophic character, in the winter shows mesotrophic character. Accordingly, the trophic structure of the dam lake varies to mesotrophic from oligotrophicKey Words: Dodurga Dam Lake, phytoplankton, seasonal variation, diversity index, clustering, ANOSIM, SIMPER