The effect of warm water effluent from the Takahama Nuclear Power Plant on the survival rate of the common mussel, Mytilus edulis galloprovincialis, which is one of the representative fouling organisms along the coast of Uchiura Bay was studied.
About 50 adult common mussels 60 to 80mm in shell length collected at the depth of 10 to 15 meters in the eastern part of the bay were confined in two steel cages (50×50×20cm) suspended 1 or 10 meters depth at the three fixed stations.
From April 1980 to March 1981 their mortality was checked monthly on, along with the water temperature measurement made at the surface to 10 meters depth at each station. In the August 1980, the maximam water temperature at 1 meter depth attained more than 29°C at stations 1 and 2, which were located 500 and 1000 meters from the outlet of the nuclear power plant, respectively. Only the groups suspended at 1 meter depth showed a high mortality of more than 80 percent in late September at stations 1 and 2.
It was suggested from the results obtained that the adult common mussel can not survive several days of high temperature over 29° to 30°C.