동해안 석호의 육수학적 조사(3): 화진포호

초록

Physicochemical parameters, plankton biomass, and sediment were surveyed from 1998 to 2000 at two months interval in a eutrophic coastal lagoon(Lake Hwajinpo, Korea). The lake is separated from the sea by a narrow sand dune. Littoral zone is well vegetated with loating-leaved aquatic plants. The lake basin is divided into two subbasins by a shallow sill. It has intrusion of seawater by permeation and stormy waves. Stable chemoclines are formed by salinity difference at 1m depth all the year round. DO was often very low (.1mgO2 L-1) at hypolimnion. Temperature inversions were observed in November. Nitrate and ammonium concentrations were very low (.0.1 mgN L-1), even though TN was usually 2.0~3.5 mgN L-1. TN/TP was generally lower than the Redfield ratio. Transparency was 0.2~1.7 m, and COD, TP, and TN of sediment were 3.1~40.3 mgO2 g-1, 0.91~1.39 mgP g-1, and 0.34~3.07 mgN g-1, respectively. Phytoplankton chlorophyll-a concentrations were mostly over 40 mg m-3. Two basins showed different phytoplankton communities 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 succession of phytoplankton was very fast, possibly due to sudden changes in physical conditions, such as wind, turbidity, salinity and light.

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