Effect of zooplankton community structure on the biological pump in Arctic

Zooplankton influence the biological pump in multiple ways, including production of sinking particles through fecal pellets, degradation of sinking particles through fragmentation and consumption, and active carbon transport. The importance of these processes varies, depending on the behavioral and metabolic traits of organisms, so that a community dominated by large vertically migrating herbivorous copepods would increase the vertical flux, whereas a community dominated by small aggregate-feeding copepods would contribute to flux attenuation. We investigated the vertical distribution, fecal pellet production and aggregate feeding of large primarily herbivorous calanoids compared to small aggregate-feeding copepods in the west coast of Greenland and Davis Strait in summer. We sampled zooplankton at 35 stations, using a Multinet with a 50 μm mesh, and conducted incubations to measure pellet production and aggregate feeding rates. Although the small copepods always dominated zooplankton abundance, the ratio of small vs. large copepods varied by 8-fold between the stations as did the pellet production and feeding rates. Our results demonstrated highly different particle production vs. degradation profiles between the stations and indicated that changing environment will influence the effect of zooplankton on biological pump, both through its effect on community composition and Our preliminary results indicate large differences both in proportional abundances of species and pellet production rates between the stations, suggesting that changing environment influences the effect of zooplankton on the biological pump, both through its effect on community composition and through its effect on the metabolic rates of copepods.