Nippon Suisan Gakkaishi 66 (6), 977-983 (2000)

Occurrence of Microcystis Blooms at the Water Area with high or low DIN:DIP Ratio

Yoichi Yoshida,*1 Hiroyuki Nakahara,*2 and Hiroko Fujita*2

The relationship between the occurrence of genus Microcystis (M. aeruginosa, M. wesenbergii, M. viridis, and M. ichithyoblabe) and water quality factors, such as DIN : DIP ratios, was examined at seven coastal areas of Lake Biwa and 14 ponds in the Kinki district in Japan.

The water areas where genus Microcystis occurred with high colony density were roughly divided into the following two groups: those with a low DIN : DIP (dissolved inorganic nitrogen: dissolved inorganic phosphorus) ratio (<40) and those with a high DIN : DIP ratio (>40). The group with a low DIN : DIP ratio occurred in waters with low DIN, (NO2-N+NO3-N) : NH4-N [(nitrite-nitrogen+nitrate-nitrogen): ammonia-nitrogen], and TN : TP (total nitrogen: total phosphorus) ratios, and high DIP and DOP (dissolved organic phosphorus), as compared with the group with a high DIN : DIP ratio. Regarding interspecific characteristics within a single group, there were several differences. M. aeruginosa with a low DIN : DIP ratio, in particular, occurred in waters with comparatively high DON (dissolved organic nitrogen), TN, DIP, DOP, TP, and TN×TP, and low (NO2-N+NO3-N) : NH4-N and DIN : DIP ratios.


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