Bleaching forces coral's heterotrophy on diazotrophs and Synechococcus

Type Article
Date 2019-11
Language English
Author(s) Meunier Valentine1, Bonnet Sophie2, Pernice MathieuORCID3, Benavides MarORCID2, Lorrain Anne4, Grosso Olivier2, Lambert ChristopheORCID5, Houlbreque Fanny1
Affiliation(s) 1 : ENTROPIE, IRD, UMR9220, Lab Excellence CORAIL, Noumea 98848, New Caledonia.
2 : Univ Toulon & Var, Aix Marseille Univ, CNRS, IRD,MIO,UM 110, F-13288 Marseille, France.
3 : Univ Technol Sydney, Fac Sci, C3, Ultimo, NSW 2007, Australia.
4 : Univ Brest, CNRS, IRD, IFREMER,LEMAR, F-29280 Plouzane, France.
5 : Univ Brest, CNRS, IRD, IFREMER,LEMAR, F-29280 Plouzane, France.
Source Isme Journal (1751-7362) (Nature Publishing Group), 2019-11 , Vol. 13 , N. 11 , P. 2882-2886
DOI 10.1038/s41396-019-0456-2
WOS© Times Cited 6
Abstract

Coral reefs are threatened by global warming, which disrupts the symbiosis between corals and their photosynthetic symbionts (Symbiodiniaceae), leading to mass coral bleaching. Planktonic diazotrophs or dinitrogen (N-2)-fixing prokaryotes are abundant in coral lagoon waters and could be an alternative nutrient source for corals. Here we incubated untreated and bleached coral colonies of Stylophora pistillata with a N-15(2)-pre-labelled natural plankton assemblage containing diazotrophs. N-15(2) assimilation rates in Symbiodiniaceae cells and tissues of bleached corals were 5- and 30-fold higher, respectively, than those measured in untreated corals, demonstrating that corals incorporate more nitrogen derived from planktonic diazotrophs under bleaching conditions. Bleached corals also preferentially fed on Synechococcus, nitrogen-rich picophytoplanktonic cells, instead of Prochlorococcus and picoeukaryotes, which have a lower cellular nitrogen content. By providing an alternative source of bioavailable nitrogen, both the incorporation of nitrogen derived from planktonic diazotrophs and the ingestion of Synechococcus may have profound consequences for coral bleaching recovery, especially for the many coral reef ecosystems characterized by high abundance and activity of planktonic diazotrophs.

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