東京湾奥域における主要植物プランクトンとＤＩＮ：ＤＩＰ比等との相互関係

Abstract

The relationships between the dominant phytoplankton and the water quality factors were examined at two stations in the inner part of Tokyo Bay.Monthly changes of water quality factors in the inner part of Tokyo Bay showed that DIN (dissolved inorganic nitrogen): DIP (dissolved inorganic phosphorus) ratio was high in February and March and low in October and November, while TN (total nitrogen): DIN ratio was low in January and February and high in August and September.The relationships between the dominant phytoplankton and the water quality factors were considerably variable and complex. Skeletonema costatum, Heterocapsa triquetra, Eucampia zodiacus, Chaetoceros didymum, and Chaetoceros radicans occurred in waters with comparatively high DIN:DIP ratio (>80), Ceratium fusus, Ceratium lineatum, Rhizosolenia fragilissima, and Leptocylindrus danicus did in waters with moderate DIN:DIP ratio, and Heterosigma akashiwo, Prorocentrum minimum, Gonyaulax verior, and Chaetoceros debile did in waters with comparatively low DIN:DIP ratio (<50). DIN:DIP ratio in waters where dominant phytoplankton occurred tended to decrease with increased TN×TP and WT.