Copyright : Laboratoire LEMAR- 2018
Fanny Houlbrèque (UMR ENTROPIE / PI); Anne Lorrain (WP1 leader)
National
ANR
Start Date
06/12/2025
End Date
06/12/2025
Coral reefs are important biodiversity hotspots and major ecological reserves. They are also critically important to the many countries living nearby. With global warming, extreme thermal events called Marine Heat Waves (MHWs), have devastating effects on coral reefs, inducing massive bleaching (i.e. symbiosis disruption between corals and their Symbiodiniaceae algae, depriving the coral of its main food source). Bleaching can lead to coral death if the stress persists, unless corals can rely on their heterotrophic nutrient acquisition, by consuming organic matter or planktonic preys. There is evidence that some coral communities, living in mesotrophic reefs (rich in plankton and nutrients) are less sensitive to bleaching. In laboratory, corals supplied with plankton are more resistant to heat stress but fewer studies have been conducted in the field. While MHWs are becoming more frequent and intense, areas rich in plankton and organic matter (hereafter called mesotrophic reefs) can be key to coral survival by allowing corals to obtain external energy sources. They can serve as coral refuge in the face of climate change. BOOST gathers four UMRs (ENTROPIE, LEMAR, MIO, LOMIC) and three international partners, the CSM, Duke University and KAUST on a highly multidisciplinary project merging ecophysiology, biogeochemistry, oceanography and remote sensing. Laboratory and in situ approaches are applied in BOOST to: (1) (a)Determine whether mesotrophic reefs show higher metabolic performances, and (b)whether corals from oligotrophic reefs can adapt to mesotrophic conditions, by measuring in particular their productivity and calcification with innovative equipment using high-frequency sampling, and by transplanting corals from oligo- to mesotrophic reefs and assess their physiological parameters; (2) Confirm, under in situ conditions, that corals from mesotrophic reefs are more resistant to bleaching by performing short-term acute heat stress on corals collected either meso- and oligotrophic reefs and transplanted from an oligotrophic reef; (3) Assess that coral tissue properties reflect the seawater nutrient properties and enable the determination of coral heterotrophic levels in situ by measuring new heterotrophic markers (bulk isotopic δ13C and δ15N values, some δ15N-compound-specific amino acid values and a fatty acid biomarker (cis-gondoic acid)) calibrated in corals cultivated in laboratory conditions, under different diets; (4) Localize other mesotrophic reefs, where corals may be more resistant to future MHWs, by analyzing satellite images of surface chlorophyll-a around New Caledonia.
BOOST will provide new tools to help policymakers and environmental managers decide where to focus their efforts to preserve areas resilient to climate change, and thus essential for reef protection and restoration. With BOOST results, the heterotrophic status of corals could be finally considered as a valid nature-based solution and a next step might even be to seed portions of the reefs with plankton and organic matter.
Laboratory Members
Contributors
UMR ENTROPIE : Fanny HOULBRÈQUE, Riccardo RODOLFO-METALPA, Corina IOVAN, Hugues LEMONNIER, Sylvie FIAT, Florence ANTYPAS, Mahé DUMAS, Valentine MEUNIER
MIO : Martine RODIER, Sophie BONNET, Mercedes CAMPS
LOMIC :Mireille PUJO-PAY
CSM (Monaco) : Christine FERRIER-PAGES, Cecile ROTTIER
Duke Univ. (USA) : Nicolas CASSAR, Katryna NIVA
KAUST (Saudi Arabia) : Michael FOX
