The relationships between chlorophyll-a dynamics and certain physical and chemical variables in the temperate eutrophic Çaygören Reservoir, Turkey

The Çaygören Reservoir was sampled monthly from February 2007 to January 2009 at three stations to determine the relationships between the chlorophyll-a (Chl-a) dynamics and soluble reactive phosphorus (SRP), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), water discharge, water transparency, water temperature (T), specific conductance (SC) and pH. Thermal stratification occurred in the reservoir from May to September. The maximum chlorophyll-a concentrations were measured (using a YSI multi probe) in the fall and the minimum concentrations were recorded in the winter. Differences in the concentrations of chl-a , SRP and NO3-N were significant among seasons (p < 0.01), but not among sampling stations (p>0.01). The differences in the Secchi disk transparency were significant both among sampling stations and seasons (p < 0.05). The results of this study suggest that high chl-a concentrations resulted from the increase in available light in the spring and deep mixing in the fall which provided nutrients needed for phytoplankton growth.