한국 서해안 조간대에서의 환경변화에 따른 중형저서동물군집의 다양성

Abstract

The community structure of major meiobenthos was studied in Chunsu bay on west coast of Korea in april, July and october, 2003. Chunsu bay, one of the famous spawning ground and nursery in west coast of Korea, was reduced to half of the total area and estuary of bay almost disappeared by construction of Seosan A, B dike. So, Chunsu bay is semi-closed and influenced by environmental stress like decreasing inflow of stream and increasing discharge of sewage by coastal development. The samples for analysing benthic micro-organism, benthic diatom and meiobenthic animal were collected using the van-Veen grab and acryl sub-corer at 11 stations in Chunsu bay. To examine feeding habit of major meiofaunal groups, nematodes and harpacticoid copepods at the Hwangdo tidal flats in inner part of Chunsu bay. Grazing rate was measured using a isotope-tracer (3H thymidine, 14C amino acid) method. Time-serial measurement of grazing rate was made to elucidate the effects of day/night and tidal cycle on diel feeding rhythm of the animals. The number of culturable bacteria fluctuated from 1.73±0.25×105 to 18.23±1.17×105 CFU/㎤ during the experimental period, and was highest in october. The numbers of culturable bacteria in the study sites were higher at the station near the entrance of bay than the station of inner part of bay, and fluctuated from 2.12±0.06×106 to 4.27±0.28×106 CFU/㎤ at the the Hwangdo tidal flats in October. Variation of the number of culturable bacteria by tidal rhythm showed higher in day than night time. The Concentration of Chl.a in the sediment at the study site was 18.0～168.2㎎/㎡ in April and 36.6～111.0㎎/㎡ in October. The most abundant meiobenthos was nematodes and followed by sarcomastigophorans, harpacticoid copepods. These Three taxa comprised more than 80% of the total abundance at all stations. For size distribution analyses showed that animals which fit into the sieve mesh size of 0.063mm were abundant. The maximum density of meiobenthos was