Water Temperature at Shores of Lake Kasumigaura in Summer

Abstract

We present a study on lakeshore water temperature (WT) in Lake Kasumigaura from July to September 2022. WT was monitored at 17 lakeshore sites using WT loggers. The results show that the lakeshore WT was higher during the daytime and lower during the night than the WT at the center of the lake. The highest lakeshore WT reached 37.4 ℃. Additionally, two factors were examined, the breakwater and the mouth of the river, which may affect WT. It was found that WT at the lakeshore with a breakwater tended to be higher during the daytime and lakeshore WT also seemed to be affected by the existence of the mouth of the inflowing river. Abnormally high WT was observed at the shores of Lake Kasumigaura in summer, which possibly resulted in the decrease in the smelt and mussel (Nodularia douglasiae nipponensis) populations. As global warming continues to cause an increase in average air temperature, lakeshore WT will rise and reach higher temperatures than before. Therefore, continuous monitoring of lakeshore WT is essential to protect the lakeshore ecosystem from the effects of global warming.