Phosphorus as a Possible Factor Stimulating the Appearance of Anabaena Bloom in the South Basin of Lake Biwa

Abstract

In the summer of 1986, the depletion of dissolved inorganic nitrogen (DIN) in the lake water persisted for about two months from mid August to early October in the south basin of Lake Biwa. An Anabaena bloom appeared about a half month later from the onset of this DIN depletion and persisted for about one month. During the period of Anabaena bloom, both total and particulate phosphorus concentrations were much higher than in the preceding period. Thus, it was suggested that, in addition to the DIN depletion, phosphorus supply to the lake water from somewhere stimulated the massive growth of Anabaena.