Identifying the dominant processes (physical versus biological) in pelagic marine ecosystems from field estimates of chlorophyll a and phytoplankton production

A new approach is described to identify the dominant process (physical versus biological) in a pelagic marine ecosystem, from simple biological oceanographic field variables. The approach is based on quantification of the matching (M) between phytoplankton production (P) and losses, from field estimates of chlorophyll a (Chl) and P. Coefficient M is estimated for a wide range of oceanic and coastal environments and of trophic characteristics, using data from the literature. Results show that M characterizes the dominance of physical versus biological processes in pelagic systems. The coefficient may be especially useful as a means for extracting process information on pelagic marine ecosystems from large data sets of Chl and P, e.g. recorded by moored instruments or provided by satellite images of ocean colour.