Spatio-temporal changes of macrobenthic community structure in different habitats around Galsa delta of Gwangyang Bay, Korea

초록

Macrobenthic communities from three different habitats of intertidal, eelgrass bed (Zostera marina) and subtidal around Galsa delta in Gwangyang Bay, Korea were compared to investigate the effect of habitat difference on species composition, abundance and biomass. Macrobenthos were monthly sampled from March 2001 to May 2002 at eight stations on a transect covering three habitats. Water column and sediment characteristics were also investigated for the habitats. A total of 391 species was identified. Eelgrass bed showed 1.5 times greater species density (the number of species per core), 3.5 times greater abundance and 4.6 to 7.1 times greater biomass than other habitats. As demonstrated by stepwise linear regression analyses, the presence of eelgrass was primarily attributable to the differences. Adding of epifaunal components to the bed has specific importance in terms of speicies richness, abundance and biomass in this bed because most of the infauna in the bed was not typical species of eelgrass community but the components extended from the nearby bare substrates. There were several dominants featuring each habitat. In lower intertidal area, tanaid Leptochelia itoi, polychaetes Scoloplos armiger and Lumbrineris cruzensis were representatives. In the eelgrass bed, several epifauna (amphipods Ericthonius pugnax, Jassa slatteryi and Caprella tsugarensis) and infauna (polychaete Lumbrineris longifolia, bivalve Macoma incongrua, ophiuroid Ophiura kinbergi) dominated. In subtidal area, polychaetes Tharyx spp., Paraprionospio pinnata and bivalve Theora fragilis were characteristic. Seasonal variation pattern of macrobenthic community structure differed among habitats. Seasonal variation of water column properties such as water temperature was closely related to the differences but the details were different depending on the types of habitat. In eelgrass bed, shoot density was an influential factor in controlling seasonal variation of infauna community, whereas shoot