Many marine organisms perform vertical migrations, as they seek to balance their feeding opportunities and predation risk. Metazoans from zooplankton to fish perform diel vertical migrations (DVM), typically spending the day at depth hiding from visual predation, before ascending to the surface to feed at night. Copepods, especially in polar regions, perform seasonal vertical migrations (SVM), diapausing at depth during unfavorable months before migrating back to the surface when food becomes abundant. These two vertical migrations (daily and seasonal) actively transport organic carbon from the ocean surface to the depth, contributing to the biological carbon pump.

      Here, we provide estimates of carbon export (the flux of carbon from the surface to the depths) and carbon sequestration (the amount of carbon stored in the ocean’s interior) mediated by these vertical migrations. While the export production of metazoans is modest (∼20 % of global total), we estimate that their contribution to carbon sequestered by the biological pump (∼800 PgC) is conservatively more than 50 % of the estimated global total (∼1300 PgC). Fish and mesopelagic fish in particu lar appear to contribute significantly to global carbon sequestration.