Original paper

The relationship between environmental variables and the vertical and horizontal assemblages of phytoplankton in Erfelek Reservoir in Sinop, Turkey

Tezel Ersanlı, Elif; Haısrcı, Seda


Temporal and spatial variation in phytoplankton community structure and the effects of physicochemical parameters on the vertical and horizontal distributions of phytoplankton were investigated between August 2010 and July 2011 in Erfelek Reservoir in Sinop which is used for irrigation and drinking water supply. A total of 73 taxa were identified belonging to Cyanophyta, Ochrophyta, Chlorophyta, Streptophyta, Dinoflagellata and Euglenozoa. The Ochrophyta was dominant in terms of both population density and number of species in the reservoir. The Ochrophyta division increased and the Chlorophyta division decreased from the surface to the bottom of the reservoir. Cyanophyta members preferred the surface and depths of 1 m and 4 m, but no important difference was observed for Euglenozoa and Dinophyta. Canonical Correspondence Analysis indicated that oxidation-reduction potential and nitrate were negatively correlated with temperature while the correlation between oxidation-reduction potential and nitrate were positive. In addition, temperature has an indirect effect on the distribution of species. Diversity index values show that the reservoir water was between the groups of partly polluted and unpolluted areas. Non-metric multi-dimensional scaling analyses showed that environmental variables followed the same seasonal changes at the surface and at depth.