Seasonal changes of Uroglena americana in Lakes Chuzenji-ko and Yuno-ko.

概要

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Seasonal changes and vertical distribution of Uroglena americana, which is known to cause fishy odor of tap waters, were surveyed in Lakes Chuzenji-ko, Yuno-ko, and the mouth of the Yukawa River, which connects the two lakes, during 1983 to 1985. The results were as follows (1) Remarkable increases in cell number of U. americana were observed from the end of May to the middle of June in Lake Yuno-ko and from the end of June to the middle of July in Lake Chuzenji-ko. The fishy odor of tap water, where Lake Chuzenji-ko was its source, occurred for the same period as that in blooming of U. americana in 1983. (2) The maximum cell numbers of U. americana were observed at surface layer in Lake Yuno-ko and at the depth of about 10 m in Lake Chuzenji-ko, where the river water flowed into the same water temperature layer during May to July, suggesting that most of U. americana might flow into Lake Chuzenji-ko through the Yukawa River and grow there. (3) Since Lake Yuno-ko has sufficient nutrient levels for growth of U. americana and the water temperature from June to October is nearly 15 C, a condition favoring growth of U. americana, Lake Yuno-ko would have supplied U. americana for Lake Chuzenji-ko for long period.
日本陸水学会の論文