Restructuring of genomic provinces of surface ocean plankton under climate change
Résumé
The impact of climate change on diversity, functioning and biogeography of marine plankton is a major unresolved issue. Here, niche theory is applied to plankton metagenomes of 6 size fractions, from viruses to meso-zooplankton, sampled during the Tara Oceans expedition. Niches are used to derive plankton size-dependent structuring of the oceans south of 60°N in climato-genomic provinces characterized by signature genomes. By 2090, assuming the RCP8.5 high warming scenario, provinces would be reorganized over half of the considered oceans and quasi-systematically displaced poleward. Particularly, tropical provinces would expand at the expense of temperate ones. Compositional shifts among planktonic grazers and nitrogen-fixing bacteria suggest impacts on the nitrogen and carbon cycles. Sea surface temperature is identified as the main driver of the changes (∼51%) followed by phosphate (11%) and salinity (10%). These results demonstrate the potential of integration of genomics with physico-chemical data for higher scale modeling and understanding of ocean ecosystem dynamics.
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