Researches on the effects of agricultural activities on sand dune lakes and measures to protect a lake ecosystem

对新泻和秋田县31个沙丘湖泊的水质进行了普查，以评价富营养化。对一些濒危物种如菜、芡实的生活史或分布，以及优势种菱的生活史或分布进行了研究。和莲的研究。对新泻市的一个典型的沙丘湖相县湖进行了深入的湖沼学研究，在湖的周边种植西瓜、烟草和日本萝卜作为主要作物，揭示了保护湖周围的芦苇区以减少农田硝酸盐氮和覆盖菱植被以调节蓝藻造成的有害水华的重要性。

General surveys on water quality of 31 sand dune lakes in Niigata and Akita Pref. were conducted to evaluate the eutrophication. Life cycle or distribution of some endangered species such as Nymphoides peltata and Euryale ferox、and dominant species such as Trapa spp. and Nelumbo nucifera inhabited in sand dune lakes were also studied. Intensive limnological studies of Lake Sagata, a typical sand dune lake in Niigata City, where watermelon, tobacco and Japanese radish are cultivated as main crops on the periphery of the lake, revealed the importance of protection of reed zone around the lake to decrease nitrate nitrogen from the farm land and covering of Trapa vegetation to regulate the harmful water bloom by cyanobacteria.