Nearshore Macrobenthic Communities off Two Nuclear Power Plants in Northern Taiwan

Abstract

The nearshore macrobenthic communities outside the Nuclear Power Plants Ⅰ and Ⅱ were monitored on a seasonal basis from winter, 2000 to summer, 2004. The animal and sediment were sampled by scuba diving. The macrobenthic assemblages, sediment characteristics and total organic content were analyzed. The macrobenthos assemblages in terms of species richness, density and biomass was determined. The mean grain size and sorting (i.e. inclusive graphic standard deviation) of sediment were also determined. The small-sized annelids and crustaceans were the dominant macrobenthos. A total of 96 species of macrobenthos was found in the sediment near the Nuclear Power Plant Ⅰ. The sediment was composed mainly of moderately sorted coarse sand, with silt-clay content less than 2%. The total organic Content ranged from less than 1% to 7%. A total of 86 species of macrobenthos was found in the sediment near the Nuclear Power Plant Ⅱ. The sediment composed mainly of moderately well sorted medium sand, with silt-clay content equal or less than 4%. The total organic content ranged from 1% to 4%. The short distance between two power plants resulted in about 50% of species shared by both plants. Statistical analyses showed that the macrobenthic communities in the relative open system outside the Power Plant Ⅰ were more affected by season than by the sediment characteristics. The relative protected environment outside the Power Plant Ⅱ resulted in higher habitat diversity. The sediment characters strongly influenced to the macrobenthic communities. The synoptic comparisons between two power plants showed that in spite the differences in the microhabitat, the nearshore macrobenthic communities in the Northeast Taiwan were mainly affected by the sediment characters. Seasonal variation was the secondary factor. Results of this study found that the influence of thermal effluent from the power plant to the nearshore macrobenthic community structures was rather localized. Nearshore macrobenthic communities appeared to have reached a stable condition with the constant environmental disturbances from the power plants.