Spatial and temporal characterization of the physicochemical parameters and phytoplankton assemblages in Dodurga Reservoir (Sinop, Turkey)

Physicochemical parameters and phytoplankton seasonal variation were investigated between August 2010 and July 2011 in Dodurga Reservoir. A total of 35 phytoplankton taxa were identified. Phytoplankton samples collected from surface samples in late winter, spring, and early and mid-summer were found to be influenced by nitrate, dissolved oxygen, pH, temperature, and phosphate. However, early winter and autumn assemblages of the samples were influenced by total hardness, silica, water transparency, conductivity, organic matter, and oxidation reduction potential. The phytoplankton samples collected from different depths in early and mid-summer were found to be influenced by only temperature. Early and middle spring assemblages of the samples were affected by pH, dissolved oxygen, and conductivity, while winter samples fluctuated according to conductivity and oxidation reduction potential. The phytoplankton abundance increased in the spring and early summer. High phytoplankton abundance was recorded in the transition zone as a result of decreasing flow velocity and light penetration. The maximum number of total organisms in depth samples was observed at the depth of 2-4 m, reflecting availability of light and temperature.