Seasonal Dynamics and Biomass of Mixotrophic Flagellate Dinobryon sertularia Ehrenberg (Chrysophyceae) in Derbent Reservoir (Samsun, Turkey)

Abstract

Mixotrophic protists, combining both heterotrophy and phototrophy, are found abundantly in eutrophic waters. Dinobryon sertularia Ehr. from Chrysophyceae (golden algae) are mixotrophic organisms often make up blooms and colony in pools, lakes and clam reservoirs. This study was carried out in Derbent Dam Lake in the Middle Black Sea Region. Seasonal dynamics and biomass of D. sertularia were investigated at four stations between February 2001 and July 2002. D. sertularia consisted of 47-60% in spring, 61-79% in summer, and 82-88% in autumn of all phytoplankton population. In August 2001, D. sertularia was calculated in the highest amounts numbers (18,740-13,140 cells ml(-1)). This species provided important contributions to phytoplankton biomass. In the present study, it was found that there is an inverse correlation between water depth and phytoplankton biomass production. According to Bray-Curtis Similarity Indice, 88% similarity was determined among Station 3, Station 4 and 4-6 m of Station I. D. sertularia was dominant and common organism in all seasons. The reservoir water was defined as oligomesotrophic and alkaline characters (pH 7.98), and average temperature was 15.56 degrees C.