Seasonal Variation and Indirect Monitoring of Mycrocystin Concentrations in Daechung Reservoir, Korea

Water and algal samples were collected weekly from Daechung Reservoir, South Korea, during the period of cyanobacterial blooms, and concentrations of microcystin were measured using a protein phosphatase inhibition assay and high-performance liquid chromatography. Measurable microcystin levels were detected in dissolved and particulate fractions in all examined samples. The microcystin concentration in particulate form increased dramatically after August, whereas that in the dissolved phase did not very considerably. Overall, the microcystin concentrations in dissolved form were approximately 28% of those in particulate form. The chlorophyll a concentration was correlated highly with phytoplankton numbers and cyanobacterial numbers. The microcystin concentration was determined to some extent by the particulate nitrogen/phosphorus ratio.