Copepod community structure and physiological rates shape the biological pump during early North Atlantic spring bloom

Zooplankton plays an important role in the biological carbon pump, and zooplankton biomass and community structure can have a large influence on the sedimentation/remineralization balance of the water column. We investigated the potential effects of zooplankton community structure and eco-physiology on the export and attenuation of vertical flux during an early North Atlantic spring bloom, using Calanus finmarchicus as a representative of large vertically migrating calanoids that primarily feed on suspended phytoplankton and produce large fast sinking fecal pellets, and Microsetella norvegica, Oncaea/Triconia spp. and Oithona spp. as representatives of aggregate- and detritus-feeding copepods. We measured (1) diurnal changes in the pellet production, egg production and respiration rates of Calanus finmarchicus and (2) weight-specific egg production of egg-carrying non-calanoid copepods and combined these with (3) the vertical distribution of copepod biomass and species composition. Our results demonstrated many-fold differences in the carbon demand of the copepod community over a few weeks of winter–spring transition, as well as many-fold differences in the vertical profiles of particle production vs. degradation depending on the zooplankton community structure.