Micro- and Macrozooplankton on the Nova Scotian Shelf in the Prespring Bloom Period: A Comparison of Their Potential Resource Utilization

Mean abundance and organic carbon content of the microzooplankton community in the euphotic zone across the Nova Scotian Shelf in late winter ranged from 1.22 × 102 to 1.63 × 103∙L−1 and 1.61 to 7.0 μg C∙L−1, respectively. Microzooplankton carbon was 4–13% of the phytoplankton carbon and 55–456% of the macrozooplankton carbon. There was no evidence of onshore–offshore gradients in microzooplankton distribution, primary productivity, standing stock of phytoplankton, or macrozooplankton biomass. Estimated ingestion and respiration rates of microzooplankton and measured ingestion and respiration rates of macrozooplankton suggest that phytoplankton carbon or daily primary production probably would be sufficient to satisfy respiratory carbon requirements of both groups of herbivores but growth and reproduction could not have been sustained without ingestion of nonplant carbon.