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Biodiversity and the deep oceanic floor

An international team (Norway Switzerland, France, United Kingdom, Germany, Spain, United States) with researchers from the CEA (Genoscope, CEA-Jacob), the CNRS, Ifremer and Sorbonne University has produced a dataset of the deep ocean floor and compared it to the other oceanic realms at a worldwide scale. The results, published in the 4 February 2022 edition of Science Advances, show that the deep oceanic floor is home to a mostly unknown biodiversity largely superior to that of plankton. The team sheds light as well on the complex relationships between planktonic and benthic (relating to the ocean floor) organisms within the ocean's vital carbon pump function. 

Published on 7 February 2022

Genoscope was part of a study published in Science Advances wherein an international team of researchers massively sequenced environmental DNA extracted from hundreds of deep-ocean sediment samples collected during 15 expeditions across all of the earth's major oceanic basins. Their sequences were integrated into similar data on the oceans' other realms collected by the Tara Oceans and Malaspina expeditions. That collective dataset provides a first uniform and planetary vision of oceanic eukaryotic biodiversity. 

The international team's comparison of biodiversity across the oceans' strata, including their floors, showed that only a small portion of planktonic species (largely the plus abundant, but not necessarily those that are thought to be important for the biological carbon pump) reach the deep-ocean sediment. The planktonic communities that sink to the ocean floor change little in composition and the planktonic biodiversity present in the sediments as revealed by DNA sequencing enables the prediction of variations in the annual surface-to-floor flow of organic carbon. The results of the study show that biodiversity is a key factor in the transfer of atmospheric carbon to the ocean floor, where it may remain for millennia.

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