Structure and distribution of polychaete communities in various habitats in Korean seas

Abstract

There are various water masses and sediment types in the Korean seas. The Yellow Sea is characterized by a megatide of 9 m and wide tidal flats, while the East Sea is characterized by a variety of currents and generally deep waters. Because of these diverse environmental conditions, there are numerous habitats to which various benthic animal species have adapted. In particular, studies of benthic polychaetes-which are the major components of benthic ecosystems, are sensitive to environmental changes, and are used as major taxa in environmental evaluations-have focused on coastal areas and estuaries. In this study, the polychaete community structure was investigated in various habitats in the Korean seas; the faunal composition and distribution were compared using data collected from larger sampling areas. In the central Yellow Sea, where there is cold bottom water, there were 130 species, while the estuary contained 97 species. The mean habitat density was 960 individuals/m2 in the estuary compared with 275 ind./m2 in the offshore areas. The dominant species in this area of the Yellow Sea was Spiophanes bombyx and the feeding guild was FDT (i.e., filter feeder, discretely motile, tentaculate). The dominant species in the estuary were Heteromastus filiformis, Ampharete arctica, and Loimia sp.; deposit feeders were predominant. Ulleungdo and Dokdo are located in the central East Sea, a good environment for benthic animals because of the shallow water, various currents, and complex sedimentary layers. In addition, there was a substantial difference in water depth within the survey area, and there were various types of sedimentation. In the East Sea, Ulleungdo had more polychaetes (119 species) than did other regions; it also had the highest mean density (772.8 ind./m2). The geographic characteristics of Ulleungdo Island had a considerable influence on the polychaete community. The dominant species in Ulleungdo were Pseudobranchiomma zebuensis, Scolelepis sp., and Haplosyllis spongiphila. Similar to other regions, the proportions of Sabellidae and Spionidae were high. Polychaetes community and species composition were compared in six areas (Yellow Sea offshore, Yellow Sea estuary, East Sea Ulleungdo, East Sea offshore, subtidal zone around rocky reefs in the East Sea, and South Sea). The number of species was highest in the South Sea (159 species), and the density was highest in the Yellow Sea estuary (960 ind./m2). The cluster analysis was well divided by region [not understood]. The differences in species diversity were largely attributable to sedimentation type and water depth; the large sampling area resulted in high species diversity. This study investigated the distribution, biomass, density, diversity, and feeding combinations of benthic polychaetes inhabiting various environments in the Korean seas, together with the environmental factors that affect these characteristics. In addition, the correlations between distribution patterns of benthic polychaetes according to the region and environmental variables were evaluated.