A seasonal copepod ‘lipid pump’ promotes carbon sequestration in the deep North Atlantic

Estimates of carbon flux to the deep oceans are essential for our understanding for global carbon budgets. We identify an important mechanism, the lipid pump, that has been unrecorded in previous estimates. The seasonal lipid pump is highly efficient in sequestering carbon in the deep ocean. It involves the vertical transport and respiration of carbon rich compounds (lipids) by hibernating zooplankton. Estimates for one species, the copepod Calanus finmarchicus overwintering in the North Atlantic, sequester around the same amount of carbon as does the flux of detrital material that is usually thought of as the main component of the biological pump. The efficiency of the lipid pump derives from a near complete decoupling between nutrient and carbon cycling and directly transports carbon through the meso-pelagic with very little attenuation to below the permanent thermocline. Consequently the seasonal transport of lipids by migrating zooplankton is overlooked in estimates of deep ocean carbon sequestration by the biological pump.