뱀장어 養鰻場의 플랑크톤 組成 및 出現量에 關한 硏究

Plankon composition and standing crops in culture tank of Eel, anguilla japonica

This study was carried out to examine the on plankton species composition and standing crops in three eel culture tank, which lies at Yochun kun, Chunnam province. In the experimintal eel culture tank, it was found that optimal rearing water temperature was 27~30℃. When dinal difference of temperature fluctuate more than 3℃, feeding condition was very precarious and feed loosing rate was increased. DO need to keep beyond at 4.5㎎/L each concentration of nitrite should maintain less than 10.0ppm under high temperature and pH. In addition, pH level must always keep optimal range(6.0~8.0) steadily. Aproprite phytoplankton population in culture tank of eel was about 7.25×10⁵cell/L. High density of population(above 7.25×10⁵cell/L) was result in unfavorable water quality. Most of appearanced species(phytoplankton) were composed of hypernutrition species, and dominant species(Microcystis aeruginosa, Anabana spiroides) were profitable for brown-water making by blooming in summer. Zooplankton(Brachionus sp., Daphnia sp.) appeared about more than 15 ind./L under less than 5.5 pH level and water change was occur in this condition. Experimental culture tank of eel under water temperature 27~29℃, DO 3.5~7.6ppm, pH 6.0~8.4, appearance of plankton 60 species, density of plankton 7.25×10⁵~7.25×10⁷cell/L, showed most faborable feeding condition. In this tank, dominant plankton was blue-green algae(Microcystis aeruginosa, Anabaena spiroides, Coelosphaeriun kutzingianum) which created brown-water making, and although zooplankton, Brachionus sp. was appeared about less than 5 ind./L water change not happened.