양재천의 수환경과 수서동물군집 특성

Characteristics of Water Environment and Aquatic Animal Community in Yangjae Stream, Seoul

The present study was performed to analyze community structure of aquatic animals and to estimate biological water pollution levels in Yangjae stream from April to December, 1997. The aquatic animals were composed of 49 species, 12 orders, 7 classes in 4 phyla. The seasonal species of whole area showed big fluctuation between 18 species in Spring, 30 species in Summer, 35 species in Autumn and 15 species in Winter. The regional species of the survey period showed 35 species at Umyeon bridge, 24 species at Youngdong 1 bridge, 21 species at Youngdong 4 bridge and 25 species at Taech´i bridge site. The major dominant species of benthic macroinvertebtates were chironomidae sp.1, chironomidae sp.2, chironomidae sp.5 in diptera, Limnodrilus sp.1, Limnodrilus sp.2 in oligochaeta, Physa acuta in mollusca and Ischnura asiatica in odonata. Seasonal dominance indices of benthic macroinvertebrates ranged from 0.42 to 0.96 at each site, while seasonal extended biotic indices(EBI) of benthic macroinvertebrates ranged from 2 to 5 at each site. According to the saprobic system based on the seasonal species diversity indices of benthic macroinvertebtates at each site, Biological water quality condition of Yangjae stream was severely fluctuated between polysaprobic area and oligosaprobic area. According to the estimation of water pollution levels by average specie diversity indices of benthic macroinvertebrates, all study sites are determined α-mesosaprobic area(Youngdong 4 bridge) and β-mesosaprobic area(Umyeon bridge, Youngdong 1 bridge and Tach´i bridge). The aquatic animals in Yangjae stream has been endangered by channelization of water course and cementation of riparian. Yangjae stream ecosystem was considerably simplied by rearangement project at Kangnam-ku, Seoul in 1997. For the analysis of fluctuation of aquatic animal community by simplified ecosystem, long-term survey is needed.