In the inner part of Tokyo Bay,
Heterosigma akashiwo dominantly occurred and red tides were sometimes formed from May to July. The relationship between the dominant occurrence of
H. akashiwo and water quality or meteorological factors was examined, referring to the Tokyo Metropolitan Government's and the Meteorological Agency's data.
In early June of 1984-1995, the yearly changes of water quality in the inner part involved a remarkable fluctuation of TN (total nitrogen), TP (total phosphorus), DIN (dissolved inorganic nitrogen), DIP (dissolved inorganic phosphorus), TN:TP, DIN:DIP, TN:DIN, and TP:DIP ratios.
The comparison of each average water quality with the dominant species of phytoplankton in early June of 1984-1995 showed that
H. akashiwo dominantly occurred in the waters with high water temperature, high concentrations of TN, TP, DIN, and DIP, high value of TN×TP, low salinity, and low ratios of TN:TP, DIN:DIP, TN:DIN, and TP:DIP. The species occurred in the years with meteorological conditions of high air temperature, long times of sunshine, high wind velocity, and moderate precipitation, during May. These characteristics of water quality or meteorological factors suggested close connection to the physiological characteristics of
H. akashiwo, such as the utility for dissolved organic nitogen.
抄録全体を表示