Phytoplankton growth, microzooplankton grazing, and carbon cycling in marine systems

We present an analysis of the global impact of microplanktonic grazers on marine phytoplankton and its implications for remineralization processes in the microbial community. The data were obtained by an extensive literature search that yielded 788 paired rate estimates of autotrophic growth (µ) and microzooplankton grazing (m) from dilution experiments. From studies in which phytoplankton standing stock was measured in terms of carbon equivalents, we show that the production estimate from dilution experiments is a reasonable proxy (r = 0.89) for production determined by the standard 14 C method. The ratio m: µ, the proportion of primary production (PP) consumed by micrograzers, shows that microzooplankton…