낙동강 (洛東江) 하구의 환경특성과 저서성 (底棲性) 대형무척추동물의 (大型無脊椎動物) 동태에 (動態) 관한 연구 = Study on the Environmental Characteristics and Dynamics of Benthic Macroinvertebrates in Naktong Estuary

다국어 초록 (Multilingual Abstract)

The authors carried out this research during the period from Apri1, 1984 to September, 1987. The obtained results from the study on the physicochemical factors and ecological dynamics of benthic macroinvertebrates in Naktong estuary are as follows. 1. Physicochemical factors showed seasonal fluctuations by variable freshwater inflow from upper stream, and also they were impacted by tidal actions. Especially, temperature, dissolved oxygen and salinity showed large fluctuations according to seasons. 2. The survey sites were classified as three similarity types. The first type was East coast of Ulsukto (St. 6) and Chinudo (St. 10). These sites were located in the mixo-polyhaline brackish region. In this region, the subsites showing the closest relationship of species composition were South coast of Ulsukto (St. 6-1) and Paekhapdung (St. 8-1). The second type was sites of between Kup`o (St. 2) and West coast of Ulsukto (St. 5). Among these sites, Maekto-ri (St. 3) and West coast of Ulsukto (St. 5) showed the highest similarity relationship. The third type was Mulgum (St. 1) and Chomanp`o (St. 11). These sites were limnetic regions and appeared very low similarity relationships in comparison with other sites. 3. Reccurrent groups based on the index of affinity between co-occurrence species consisted of 4 groups. The first group obtained in the analysis consisted of 17 species: marine species and estusrine species which have a marine affinity. The second group consisted of 5 species: marine species which live in the mixo-polyhaline zones and below them. The third group consisted of 5 species: estuarine species which live at the low estuarine salinity zones. The fourth group consisted of 5 species which are limnetic species. 4. By the stepwise multiple regression analysis for each zone and reccurrent group which are affected by environmental factors, salinity appeared as the most important factor, and temperature, pH, turbidity, dissolved oxygen and sediment appeared as stimulating factor. 5. According to the results of stepwise multiple regression analysis, the sudden salinity-shock should be avoided in lower zones of the barrage after the Naktong estuary barrage construction. Besides, fresh water should be discharged at broad area as possible to improve the biological productivity in the estuary.