1Ibaraki Kasumigaura Environmental Science Center, Tsuchiura, Ibaraki 300-0023, 2Civil Engineering & Eco-technology Consultants, Higashi-ikebukuro, Tokyo 170-0013, 3Institute of Mountain Science, Shinshu University, Suwa, Nagano 392-0027, 4Department of Environmental Sciences, Faculty of Science, Shinshu University, Matsumoto, Nagano 390-8621, Japan
This study examined the influence of hydraulic turnover rate on apparent specific growth rate and maximum biomass of Microcystis in Lake Suwa from 1992 to 2003. The apparent specific growth rate of Microcystis decreased by flushing (>20% day−1 of the hydraulic turnover rate in a day). In addition, the apparent specific growth rate of Microcystis began to be suppressed when the turnover rate reached >2% day−1 in the exponential growth phase. The maximum biomass of Microcystis was affected by the hydraulic turnover rate from June to July. Therefore, we suggest that the short period and long-term changes of hydraulic turnover rate have large impacts on Microcystis bloom in Lake Suwa.