Seasonal Variations of Phytoplankton Blooms in Suat Uğurlu (Samsun - Turkey)

Abstract

The seasonal variations in phytoplankton blooms in Suat Uğurlu Reservoir were studied between July 1992 and December 1993. In certain months, the species Asterionella formasa Hassal, Cyclotella planctonica Brunthaler, Melosira granulata (Ehr.) Ralfs (Bacillariophyta): Pediastrum simplex Meyen, Pandorina morum Borry (Chlorophyta) and Ceratium hirundinella (O F. Müller) Schrank (Dinophyta) produced blooms in the lake. During the study period, the measured N/P ratio in the water varied from 10.3 mg/lt to 62.5. In accordance with these variations, P. simplex, P. morum and C. hirundinella, which consume high levels of phosphate, produced blooms in summer, whereas the blooms in winter were produced by A. formosa, C. planctonica and M. granulata, which consume more nitrate than phosphate.