The importance of the DOC pool for primary production estimates

Phytoplankton release of dissolved organic matter has important consequences for the planktonic ecosystem. Their effects can be compared with those expected at the rates of dissolved organic carbon (DOC) release measured in field incubations. Calculated DOC release rates must be consistent with other incubation measurements, such as those for bacterial growth and for nitrate and ammonia uptake. In this paper, comparisons are made between these different sets of measurements, showing that there is no need for DOC excretion of more than 0.1 of net primary production to account for ecological effects. Furthermore, a simple model of DOC release during productivity measurements shows that grazing on phytoplankton and on bacteria during an incubation can also be important sources of fixed C loss.