Ecological Changes of the Coastal Ecosystems before and after Operation of the Tidal Power Plant around the Sihwa Lake, Korea

초록

Lake Shihwa situated on the western coast of Korea was artificially formed by the construction of dike in 1994 for land reclamation and creation of fresh-water reservoirs. But the dike construction led the desalination, eutrophication and seasonal development of bottom water hypoxia and anoxia inside the lake due to the various pollutants from the adjacent industrial complexes, freshwater discharge from nearby tributary streams, and insufficient circulation of the seawater. Since then, to solve this problem, it has been managed mainly by means of sluice control from 1997 to 2011. In the end, Korean government made a decision in December 2002 to construct a tidal power plant to improve the water quality but also to generate the electricity. After seven years of construction, the tidal power plant was completed in July 2011, test-operated in August 2011, and in full operation since January 2012. This study addresses the differences in species richness and composition right after the operation of the Shihwa tidal power plant in the inside and outside of the lake. In general, the species richness in various taxa is enhanced by the more active sluice management resulting from the operation of the tidal power plant. The main results from the initial monitoring program are summarized as follows; 1) Water quality slightly improved due to the increased water exchange through the plant gates. 2) Differences for phytoplankton and zooplankton communities were not evident but the species richness in zooplankton is somewhat increased. 3) In the intertidal zone, species richness in macrozoobenthos increased after operation inside the lake. 4) In the subtidal zone, it is a noteworthy feature that the species richness and composition in macrozoobenthos in the stations close to the dike in the basin area are similar to the benthic communities in the outside of the dike.