영주댐 담수 이후 저서성 대형무척추동물 군집변화

The purpose of this study is to investigate the effects of artificial disturbance by analyzing and comparing the survey data of the Yeongju dam located in Yeongju-si, Gyeongbuk before and after impoundment. We surveyed four sites between the downstream of sediment control to the downstream of Yeongju Dam four times between April and October 2018. The macroinvertebrate data before the survey were gathered from the literature. The total number of benthic macroinvertebrates we observed was 35,037 ind./m², including 77 species, 48 families, 14 orders, 7 classes, and 3 phyla. The result of the community analysis showed that the dominant index increased from 0.44(±0.11) before impoundment to 0.62(±0.16) after impoundment. The diversity index increased from 2.26(±0.30) to 1.75(±0.45), the evenness index from 0.75(±0.10) to 0.66(±0.14), and the richness index from 3.11(±0.98) to 2.25(±0.81). The most dominant species changed from Hydropsychidae spp. to Chironomidae sp. The result of the Principal Components Analysis (PCA) based on Axis 1 showed that the sites of 2014 and Hydropsychidae spp. had a negative value, while the sites of 2018 and Chironomidae sp. had a positive value. In all study sites, the dominance increased while the diversity decreased. The community change was the largest in St. 2. The results of the functional group analysis showed that the scrapers increased while gathering-collectors increased among the functional feeding group and that the clingers decreased while borrows increased among the habitat oriented group. The Benthic Macroinvertebrate Streambed Index (BMSI) decreased from an average of 57.1(±8.0, C class) to an average of 30.0(±12.1, C class). St. 3 and St. 4, in particular, showed a high reduction rate.