內水面 가두리 網에 着生하는 총담이끼벌레(Bryozoa, Lophopodella carteri)의 生態와 驅除에 關한 硏究

Ecology and Extermination of the Bryozoa, Lophopodella carteri attached on the Net Cage in Freshwater

In inland aquaculture, a lot of fishes often died cause of touch of L. carteri which is attached on the net cage. In this works, the experiment were carrid out on classification of species, toxin test, and extermination with some chemicals. A bryozoa from net cage in lake Okjeong is classified into the Phylactolaemata, Lophopodella carteri Hyatt. A bryozoa broke out firstly on the 30th of June with water temperature up to 31℃ and it reattached on the net with water temperature below 30℃. Size of bryozoa colony is about O.8X0.6-1.7X 1.5cm. Water column of attachment was 0~5m and the peak is 2~3m. In toxin test on the israeli carp, goldfish and catfish touched with bryozoa for 1 minute at 25℃ of water temperature, a dead fish appeared at 20 minutes after touched. Mortality was 90% for israeli carp and 100% for goldfish at 100 minuties after touched. but catfish was not died at all. It was supposed that the toxin is from nematocyst being around tentacles and this toxin act a deadly poison on a israeli carp and goldfish. In extermination test, the bryozoa treated with 300ppm of formalin, 5% of sodium chloride, 5ppm of malachite green, 200ppm of potassium permanganate, lOOOppm of potassium iodide, lOppm of DDVP for minute respectively, all of them were not effected.