Evaluating the Potential Impacts of the Diurnal Vertical Migration by Marine Organisms on Marine Biogeochemistry

Type Article
Date 2018-11
Language English
Author(s) Aumont Olivier1, Maury OlivierORCID2, Lefort Stelly3, Bopp Laurent4
Affiliation(s) 1 : IRD IPSL, LOCEAN, Paris, France.
2 : MARBEC, UMR 248, Inst Rech Dev, Sete, France.
3 : CEA Orme Merisiers, IPSL, LSCE, Gif Sur Yvette, France.
4 : Sorbonne Univ, PSL Res Univ, Lab Meteorol Dynam, Ecole Normale Super,CNRS,Ecole Polytech, Paris, France.
Source Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2018-11 , Vol. 32 , N. 11 , P. 1622-1643
DOI 10.1029/2018GB005886
WOS© Times Cited 78
Keyword(s) ocean, biogeochemistry, ecosystem, carbon cycle, diurnal vertical migration, export
Abstract Diurnal vertical migration (DVM) of marine organisms is an ubiquitous phenomenon in the ocean that generates an active vertical transport of organic matter. However, the magnitude and consequences of this flux are largely unknown and are currently overlooked in ocean biogeochemical models. Here we present a global model of pelagic ecosystems based on the ocean biogeochemical model NEMO-PISCES that is fully coupled to the upper trophic levels model Apex Predators ECOSystem Model, which includes an explicit description of migrating organisms. Evaluation of the model behavior proved to be challenging due to the scarcity of suitable observations. Nevertheless, the model appears to be able to simulate approximately both the migration depth and the relative biomass of migrating organisms. About one third of the epipelagic biomass is predicted to perform DVM. The flux of carbon driven by DVM is estimated to be 1.05 +/- 0.15 PgC/year, about 18% of the passive flux of carbon due to sinking particles at 150 m. Comparison with local studies suggests that the model captures the correct magnitude of this flux. Oxygen is decreased in the mesopelagic domain by about 5 mmol m(-3) relative to simulations of an ocean without DVM. Our study concludes that DVM drives a significant and very efficient flux of carbon to the mesopelagic domain, similar in magnitude to the transport of DOC. Relative to a model run without DVM, the consequences of this flux seem to be quite modest on oxygen, due to compensating effects between DVM and passive fluxes.
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