びわ湖南湖における藻類異常増殖の影響要因について

抄録

To understand and control eutrofication in natural waters, it is essential to determine what factors are limiting the growth of phytoplankton algae. The statistical analysis and field survey are made about the environmental factors which have influence on extreme algal growth phenomena-water blooms-in the southern part of Lake Biwa. Statistical analysis is based on long-term daily monitoring data-water quality, algal population, and meteorological factors which were recorded by the water supply authority of Kyoto city. As a result, according to the analysis of quantification theory, it is considererd that water temerature, water level, and release rate appear to be potentially important in triggering blue-green algal blooms. Intensive field survey is made to ascertain those factors' effects on algal blooms and to understand the temporal and spatial changes of algal distribution in the lake in summer season. Finally, a simple and practical method to ditermine limiting factors using field survey data is proposed and applied.