Temperature

♤ Temperature acts along with other factors in influencing the variation of photosynthetic production.

♤ Generally, the rate of photosynthesis increases with an increase in temperature, but diminishes sharply after a point is reached.

♤ Temperature, together with illumination, influences the seasonal variation of phytoplankton production in the temperate latitudes.

Salinity

♤ Besides light and temperature, salinity also is known to influence primary production.

Grazing by Zooplankton

♤ The grazing rate of zooplankton is one of the major factors influencing the size of the standing crop of phytoplankton, and thereby the rate of production.