Sam-geun Lee, Chang-sook Kim, Eun-seob Cho and Chang-kyu Lee, Harmful Algal Blooms Research Division, National Fisheries Research and Development Institute, Busan, Korea

Abstract

Harmful algal blooms in Korea have been significantly increased in scale, duration, and frequency since 1981. Cochlodinium polykrikoides is known as one of the most harmful species in Korean coastal waters, affected an enormous economic loss on fisheries industries by the mass mortalities of marine organisms. This study aims to give a useful information for fisherman to mitigation of fisheries damages by red tide forecast when the harmful algal blooms is occurred. It was examined that 5 kinds of fish, flounder (Paralichthys olivaceus), jacopever (Sebastes schlegeli), red sea bream (Parus major), rock bream (Oplegnathus fasciatus) and filefish (Aluterus monoceros), and 4 kinds of shellfish, oyster (Crassostrea gigas), musse (Mytilus edulis), ark shell(Scapharca broughtonii) and abalone (Norditus discus) in 20 L transparent plastic tank for 3 days. Density of experimental tanks were ranged from 1,000 cells/mL to 100,000 cells/mL. The water temperature and photoperiod were adjusted to 20°C and 12L : 12D. Result of this experiment it was certified that Heterosigma. akashiwo, Alexandrium tamarense, Eutretilla gymnastica, Prorocentrum micans and Heterocapsatriquetra were not harm the examined fishes and shellfishes even with their maximum density. But C. polykrikoides killed fishes from more than the density of 3,000 cells/mL, that is, 100% of filefish, rock bream, red sea bream and flatfish were died at the density of C. polykrikoides 8,000 cells/mL within 18 hours from started examination, even though air was supplied sufficiently. And Jacopever was damaged 35% at the density of 8,000 cells/mL in 48 hours. While oyster, mussel and ark shell were not affected by C. polykrikoides during the examination. Some mucus releasing from cell of C. polykrikoides might be caused the death of fishes making respiration difficulty to the clogging of gillfilament. Also generation of reactive oxygen such as hydron peroxide, superoxide anion, hydroxyl radical might be responsible for fish mortality.