Carbon and nitrogen fluxes in the oceans: the contribution by zooplankton migrants to active transport in the North Atlantic during the Joint Global Ocean Flux Study

The role of vertical migrant zooplankton, with both seasonal/ontogenetic and daily strategies, in the active transport of carbon and nitrogen out of the surface layer in the North Atlantic is analysed. The data used were obtained mainly during the Joint Global Ocean Flux Study (JGOFS)-North Atlantic Bloom Experiment (NABE) (1989-1990) in the North Atlantic and from published information on the biochemical composition of the dominant genera/species. The resulting estimates of active transport are compared with the values of sedimentation rates at the JGOFS-NABE stations and other sites in the North Atlantic. The estimates obtained support previous findings indicating that active transport, especially by interzonal diel migrants, should be taken into account in the estimation of total carbon and nitrogen export Aux. The contribution of seasonal migrants to carbon export flux, however, has been considerably underestimated before, although it appears to be significantly lower compared to that of diel migrants. Biomass estimates and biochemical composition, together with mortality and metabolic rates, should be investigated in further detail for some of the dominant species in oceanic areas in order to evaluate active transport more precisely.