大阪湾および播磨灘におけるギムノディニウムの高密度発生と水質，気象要因との関係

Abstract

Relatioship between the blooming of Gymnodinium mikimotoi and water quality or meteorological factors was examined in Osaka Bay and Harima-nada, referring to the Meteorological Agency's data.The comparison of the average of each water quality parameter with the dominant species among phytoplankton from June to August of 1995-1997 showed that G. mikimotoi dominantly occurred in the waters with high water temperature, salinity, TN:DIN (total nitrogen: dissolved inorganic nitrogen) and TP:DIP (total phosphorus: dissolved inorganic phosphorus) ratios, moderate TN×TP and DIN:DIP ratio, and low TN, TP, DIN, DIP, and DSi (dissolved silicate). The red tide of G. mikimotoi occurred from late July to mid August of 1995 with meteorological conditions of high precipitation, high air temperature, long sunshine duration, and weak wind velocity in July.These characteristics of water quality and meteorological factors suggested that the abnormal occurrence of G. mikimotoi was closely connected with the increase of dissolved organic matter by the sudden increase and following decomposition of phytoplankton and the capability of utilization of dissolved organic matters of G. mikimotoi.