Assessment of Eutrophication and Cyanobacterial Occurrences in a Freshwater Lake, in Turkey

Abstract

Cyanobacterial dominance in lakes has received much attention in the past because of frequent bloom formation in lakes of higher trophic levels. Study area (Lake Kovada) has been used for recreational purposes; fi shing, swimming, garden watering etc. As far to our knowledge, cyanobacterial occurrence, especially Microcystis aeruginosa dominance in the lake never has been reported before. Hence intracellular microcystin analyses were performed by immunoassay from fi ltrate samples where M aeruginosa observed high in numbers. In total eighteen species belonging to 10 genera were identifi ed in the lake. Some indicators of water quality in Lake Kovada were also measured in order to characterise the trophic status of the lake. An average of 6 months for soluble reactive phosphate analysis was measured as 109.8±0.04 μg l-1. These fi ndings are even exceeding the limits for total phosphate concentration to control cyanobacterial bloom and mean ammonia was detected 668±58 μg l-1.Water quality criteria for free NH was suggested to be 20 μg l-1 by USEPA. According to the results which were obtained from the water quality analyses, the lake water is polluted and under risk of being highly populated with cyanobacteria. The effective monitoring programmes for the reduction of cyanobacterial toxin problems in waters require the identifi cation and use of appropriate guidelines worldwide

Keywords

• Cyanobacteria, Eutrophication, Lake Kovada, Microcystis aeruginosa, Water quality analyses