Hydrogeographic investigation of the east coast lagoon: Hwajinpo Lake

초록

Physicochemical factors, plankton biomass, and sediment were measured from 1998 to 2000 at two months' interim in a eutrophic shoreline Lake, Hwajinpo, in Korea. The lake is isolated from the sea by a narrow sand hill. Coastal zone is well vegetated with floating leaved marine plants. The lake basin is divided into two sub-basins by a shallow ridge. It has disturbance of seawater by stormy waves. Stable chemoclines are made by salinity variations at depth of 1 m around the year. Dissolved Oxygen was often very low (<1 mgO(2)/L) at hypolimnion. Temperature reverse were detected in November. Nitrate and Ammonium concentrations were also very low (< 0.1 mgN/L), while TN was usually 2.0 similar to 3.5 mgN/L. In general, TN/TP was lower than the Redfield ratio. Transparency was 0.2 similar to 1.7m, and COD, TP, and TN of sediment were 3.1 similar to 40.3 mg O-2/g, 0.91 similar to 1.39 mgP/g, and 0.34 similar to 3.07 mgN/g, respectively. Phytoplankton chlorophyll-a concentrations were mostly over 40 mg/m(3). Two basins showed different phytoplankton groups with Oscillatoria sp., Trachelomonas sp., Schizochlamys gelatinosa, , and Anabaena spiroides dominant in South basin, and with Trachelomonas sp., Schroederia sp., Schizochlamys gelatinosa, , and Trachelomonas sp. dominant in the North basin. The seasonal progression of phytoplankton was quick, probably because of unexpected variations in physical environments, such as salinity, turbidity, wind, and light.

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