ABSTRACT
Three marine algal sites were examined seasonally in an area of thermal discharge from the Uljin nuclear power plant in Korea to assess possible impacts from thermal stress. Quadrat samples were taken at three sites: cooling water intake, outfall and Chukbyon. The degree of wave exposure increased from intake, outfallto Chukbyon. Percent cover and biomass were response variables. All sites were, by numbers red algae, followed by brown and green algae. Over the year the maximum species diversity was also found at the Chukbyon (2.39), but the minimal one (1.67) was observed at the outfall. Seasonally generally among algal form-functional groups, filamentous and coarsely branched algae were most abundant throughout the year at the three sites. The numberof species in the jointed calcareous groups increased remarkably at the outfall. Based on these results, species richness appears tobe strongly affected by wave exposure and thermal stress. The higher proportion of calcareous form groups at the outfall sites indicates that these species are better adapted morphologically to thermal stress such as high temperatures.