Efficiency of primary production in the upper layer of the euphotic zone of the tropical North Atlantic

Parameters relating the photosynthesis in the sea to the radiative conditions are described and calculated for both eutrophic and oligotrophic waters. The radiation utilization efficiencies and photosynthesis quantum yields are compared. The quantum yield is found to increase in the regions with low chlorophyll a and nutrients concentrations. Parameters calculated from the production rates determined by means of a modified 14C method seem to be more consistent with the chlorophyll distribution and with the optical properties throughout the whole area than the parameters calculated from the production data estimated from diurnal variations in oxygen and in particulate organic carbon. (Auth.)