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.

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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.

The bioluminescent, photosynthetic, tropical marinc dinoflagellate Pyrodinium bahamense occurs in persistent high concentrations in Oyster Bay, Jamaica, W. I., although mean tidal flushing rates determined by dye-tracer techniques would predict their disappearance.As a result of a unique temporal sequence of positive phototaxis and the differential movement of diurnal wind-driven water layers of different densities, there is a daily transfer of P. bahumense into the eastern shallows of the bay where flushing rates are minimal, reducing the effect of the mean bay dilution.A second phototaxis-dependent mechanism in the eastern shallow results in zones of high concentration containing up to 10,000,000 P. buhamense per liter. This latter mechanism can explain the production of red water outbreaks in coastal waters. Nitrogen and phosphorus levels observed are consistent with both mechanisms.

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Bioluminescence and phytoplankton successions during 1969 indicate large oscillations from the stable Pyrodinium bahumense populations normally associated with bioluminescent bays. A mathematical model is proposed which relates meteo,rological conditions to positively and negatively phototactic dinoflagellate populations. The model and additional circumstantial evidence indicate that Bahia bioluminescent bay.

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