Figure 9.7. Phytoplankton primary production over time at Kingston, New York. From weekly measures of chlorophyll-A and the photosynthetic parameters three aspects of phytoplankton primary production were calculated. In A, we show photosynthesis, integrated over the entire daylight period and integrated to the depth that belowno photosynthesis occurs. This is daytime net photic zone primary production. In B, we applied a biomass-specific value of phytoplankton respiration (R; see text) and calculated both phytoplankton respiration (plotted as a negative value to simplify the figure) gross primary production. In C, we plot GPP-R, or true 24 h net phytoplankton production integrated for the entire depth of the water column. Note that expressed this way, NPP is occasionally negative and is much smaller than GPP or NDPZP.

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