Benthic Polychaetous Community in Northern Kyeonggi Bay in December 1995

This study was carried out in order to investigate the distribution and species composition of benthic polychaetous community in northern Kyeonggi Bay in September 1995. Mean density of benthic animals was 557 indiv./. Benthic polychaetes were the most dominant faunal group, comprising 60 species with a mean density of 488 indiv./. Benthic polychaetes were most abundant in Yumha Channel centering on Incheon Harbor, whereas relatively poor in the intertidal zones fringing Yongjong Island and Songdo area, and in the offshore main channel. The most dominant polychaete was Heteromastus filiformis (47.3% of polychaetous community), followed by Nephtys palybranchia, Tharyx sp., Sternaspis scutata and so on. Kyeonggi Bay could be divided into 4 regions from cluster analysis based on the dominant species composition: offsea/channel region, Incheon Harbor, intertidal zone of Yongjong Island, and intertidal zone of Songdo area. Highest species number and diversity index (H') were recorded at offsea/channel region, whereas highest faunal density at Incheon Harbor. Incheon Harbor was characterized by high abundance of H. filiformis. Compared with the previous studies carried out in Kyeonggi Bay, faunal density and species number have little changed for the recent 10 years. Dominant species was different between each study, but has been among opportunistic species of small-sized polychaetes belonging to capitellids, cirratulids or spionids. These results indicate that Kyeonggi Bay has been organically polluted steadily; specifically, this study reveals that Incheon Harbor has been the center of pollution and that the benthic community in the outer sea off Sihwa dike has become unstable.