Limnological studies of Nakdong River in Korea

Summary

During 10 years (1969–1979) we investigated the distribution of fresh water algae and fishes of the Nakdong River basin (N. 35–37, E. 128–129) in Korea. Total algal flora found in this area comprised about 290 species among which ca. 200 species were not previously recorded in Korea. Genus Hammatoidea had not been reported before from East Asia and two species, Hammatoidea brebiarticulata and H. singularis were found to be new species. Three species, Draparnaldiopsis alpina, Enteromorpha flexuosa, and Tetrasporidium favanicum were found as rare species. Raphidonema nivale was found to be abundantly distributed during summer season though it is known as a cryo-alga in the world.

Total fauna of fresh water fishes collected by the authors were 67 species. Among them 15 species, i.e., Parasilurus microdorsalis, Coreobagrus brevicorpus, Liobagrus mediadiposa- lis, Pseudoperilampus uyekii, Acheilognathus yamatsutae, Squalidus majimae, S. coreanus, Sarcocheilichthys wakiyae, Coreoleuciscus splendidus, Microphysogobio koreensis, M. yaluensis, Gobiobotia naktongenis, Cobitis longicorpus, C. rotundicuadata, Niwaella multifasciata, are endemic species to Korea.

According to the survey for ichthyofaunal study in 1978 Moroco oxycephalus was found to be the dominant species with maximum biomass of 2.1 individuals per m³.

We also examined the dynamics of the physico-chemical characteristics of Nakdong River system. The ranges of concentration variations were as follows: 5.7–9.4 for pH, 0.95–12.4 ppm for DO, 0.7–36.9 ppm for BOD, 5.01–114 ppm for COD, 0.007–2.20 ppm for PO₄^3-, 10–135 ppm for C1⁻, 0.03–20.4 ppm for NH₄⁺, 0.17–8.90 ppm for NO₂⁻, 7.4–222 ppm for NO₃⁻, 8.01–80.1 ppm for Ca²⁺, 22–241 ppm for alkalinity and 0.003–0.275 ppm for surfactants.