Abstract
The daily vertical migrations of fish and other metazoans actively transport organic carbon from the ocean surface to depth, contributing to the biological carbon pump. An important but unanswered question is whether fish play a significant role in the biological carbon pump relative to other organisms, both in terms of carbon export and sequestration. Here, we use a game-theoretic food-web model that simulates diel vertical migrations to estimate global carbon fluxes and sequestration by fish and zooplankton due to respiration, fecal pellets, and deadfalls. Despite uncertainties due to poorly constrained biomass estimates of some functional groups, a robust result of this model is that fish play a major role in the biological carbon pump. Our model estimates that open-ocean metazoans inject ~3.1 (range 1.5 - 4.7) PgC/yr of a total of ~10 PgC/yr into the ocean’s interior. Fish are further responsible for 47% (25-65%) of the oceanic carbon sequestration mediated by metazoans. This essential ecosystem service provided by fishes could be at risk from unregulated fishing in the high seas.
Competing Interest Statement
The authors have declared no competing interest.
