Diatoms are efficient transporters of carbon to the deep oceans

The oceans play a major role in climate regulation, especially because they are able to exchange carbon dioxide (CO2) with the atmosphere.

Biological processes are helpful for picking up CO2 in the surface waters. Indeed, thank to photosynthesis microalgae elaborate organic carbon by picking up CO2 in the surface waters. Because organic matter is denser than seawater this organic matter is transferred to the deep ocean where it is transformed in CO2 where CO2 stays during centuries. The transfer of CO2 from the surface ocean to the deep ocean is called “the biological pump”.

A group of scientists, belonging to research institutes and universities of Europe and of North America shows that diatoms play a major role in the biological carbon pump. Indeed, diatoms are microorganisms which need silica to build up their frustules.

For organic matter sedimenting in the oceans silica represent ballasts which help for massive an episodic transfer of marine snow to the deep ocean. In the review article published in Nature Geoscience, first the authors show that the potential of diatoms to transfer organic carbon to the deep ocean has been underestimated. Second, they also show that all diatoms are not equal as regards the export of carbon from the surface ocean.

They finally show that the ecosystem models should take advantage of the diversity of diatoms to better predict the fate of diatoms and their role in the biological carbon pump of a future warmer and acidified ocean.

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