Chalinda Ariyadej, Pimpan Tansakul, and Reungchai Tansakul

pp. 159 - 166

Abstract

Environmental variables and phytoplankton biomass as chlorophyll a in Banglang Reservoir were investigated. Phytoplankton were collected monthly from May 2000 to April 2001 from four sampling sites including the inflow from Pattani River (from Betong District), the inflow site from Balahala Forest, the middle of the reservoir, and at the spillway that helds the water before drain. Samples were taken at three levels: water surface,10 meter, and 30 meter depth. Physicochemical parameters were recorded such as nutrients (nitrogen and phosphorus), Secchi depth, alkalinity, temperature, pH, and turbidity. The results show that the average values of phytoplankton biomass at 10 meter depth were higher than that of the other depths. The maximum phytoplankton biomass was found at 10 meter depth at the inflow from the Balahala Forest sampling site in August, with a value of 12.57 mg/m³. The minimum value was found at 30 meter depth in the middle of the reservoir in July. Factors affecting the variation of phytoplankton biomass in the Banglang Reservior were ammonia, alkalinity and turbidity.