Phosphomonoester concentrations were 0 to 0.09 E.cg-atom liter-l in Chesapeake Bay from December 1972 to December 1973. Alkaline phosphatase activity associated with natural phytoplankton assemblages indicated the cells' potential to utilize the monoesters as a phosphorus source. However, ecological interpretation of alkaline phosphatase activity data is complicated by the necessity to increase the monoester concentration in order to measure enzyme activity fluorometrically.The half-saturation constant ( K, ) was 0.31 for 3-0-methyl fluorescein hydrolysis by a natural phytoplankton assemblage and 0.75 PM for glucose-6-POp by a nanoplankter in culture, and maximum velocities (V,) were 3.2 and 6.4 nm (pg Chl a h)".In one experiment with a natural phytoplankton assemblage, organisms in the 0.8-5-pm size range comprised 78% of the plant biomass and were responsible for 70% of the phosphorus uptake from glucose-6-POs when size fractionation preceded experimental incubations. Phosphomonocsters may contribute to phytoplankton phosphorus nutrition during much of the year, but are in greatest demand in spring in Chesapeake Bay.
Approximately 90 Km' of Chesapeake Bay contiguous with the Severn, South, Rhode and West Rivers were surveyed by in vivo chlorophyll fluorescence and captured samples following a large pulse of rainfall in summer, 1971. The growth and subsequent dissipation of blooms containing chlorophyll a concentrations up to 40 X pre-bloom values were completed within 21 days. A distinction is made between the blooms produced by nutrient pulses and dinoflagellate blooms normally observed in the fall. In the former, there is a complete change of phytoplankton relative species composition. The latter is a phototactic segregation of species already existing within the water column. The methodology is presented and a mathematical description is attempted.
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