Model estimates of metazoans' contributions to the biological carbon pump

Abstract

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. We use an oxygen-constrained, game-theoretic food-web model to simulate diel vertical migrations and estimate global carbon fluxes and sequestration by fish and zooplankton due to respiration, fecal pellets, and deadfalls. Our model provides estimates of the carbon export and sequestration potential for a range of pelagic functional groups, despite uncertain biomass estimates of some functional groups. While the export production of metazoans and fish 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) and have a significantly longer sequestration time scale (∼250 years) than previously reported for other components of the biological pump. Fish and multicellular zooplankton contribute about equally to this sequestered carbon pool. This essential ecosystem service could be at risk from both unregulated fishing on the high seas and ocean deoxygenation due to climate change.

Patterns and drivers of the diving behavior of large pelagic predators

“…These dives connect warm, well-lit epipelagic layers to the cold and dark mesopelagic ocean. By linking these distinct habitats via feeding at one depth and excretion at another, LPP influence biomass flows in marine food-webs, shape ecological interactions between species, and affect nutrients and carbon cycles (Doughty et al 2016; Braun et al 2022; Pinti et al 2022).…”

“…Understanding their vertical behavior could thus help management of valuable stocks. A better representation of vertical habitat utilization and predator-prey interactions would also improve marine ecosystem models used to project the evolution of wild fisheries in a changing ocean (Lotze et al 2019; Heneghan et al 2021; Tittensor et al 2021), and expand our understanding of the influence of LPP on biogeochemical cycles (Aumont et al 2018; Bianchi et al 2021; Pinti et al 2022).…”