Vertical Distribution of Environmental Factors concerned with Eutrophication in Hiroshima Bay

Relationships between POP/chl. a and DOP/POP Ratios and Photosynthetic Activity

Abstract

Vertical distribution of DIP, DOP, POP, chlorophyll-a concentrations and photosynthetic activity were monthly investigated from April 1979 to September 1980 in the northern area of Hiroshima Bay. The mean value of POP/ chl, a ratio was 2.40 (mg P/mg chl. a). For seawater in which Skeletonema costatum is contained more than 50 % in the composition, it was found that the ratio of POP/ chl. a were dependent on photosynthetic activity, being mainly influenced by solar radiation and water temperature. Further, when photosynthetic activity was extrapolated to zero, the ratio of POP/ chl. a, that is, phosphorus content in detritus was 0.05-0.08 (μg-at P/μg chl. a). DOP/POP ratios also fluctuated with photosynthetic activity.