Seagrass Thermal Limits and Vulnerability to Future Warming

Núria Marbà, Gabriel Jordà, Scott Bennett, Carlos M. Duarte

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Seagrasses have experienced major losses globally mostly attributed to human impacts. Recently they are also associated with marine heat waves. The paucity of information on seagrass mortality thermal thresholds prevents the assessment of the risk of seagrass loss under marine heat waves. We conducted a synthesis of reported empirically- or experimentally-determined seagrass upper thermal limits (Tlimit) and tested the hypothesis that they increase with increasing local annual temperature. We found that Tlimit increases 0.42± 0.07°C per°C increase in in situ annual temperature (R2 = 0.52). By combining modelled seagrass Tlimit across global coastal areas with current and projected thermal regimes derived from an ocean reanalysis and global climate models (GCMs), we assessed the proximity of extant seagrass meadows to their Tlimit and the time required for Tlimit to be met under high (RCP8.5) and moderate (RCP4.5) emission scenarios of greenhouse gases. Seagrass meadows worldwide showed a modal difference of 5°C between present Tmax and seagrass Tlimit. This difference was lower than 3°C at the southern Red Sea, the Arabian Gulf, the Gulf of Mexico, revealing these are the areas most in risk of warming-derived seagrass die-off, and up to 24°C at high latitude regions. Seagrasses could meet their Tlimit regularly in summer within 50-60 years or 100 years under, respectively, RCP8.5 or RCP4.5 scenarios for the areas most at risk, to more than 200 years for the Arctic under both scenarios. This study shows that implementation of the goals under the Paris Agreement would safeguard much of global seagrass from heat-derived mass mortality and identifies regions where actions to remove local anthropogenic stresses would be particularly relevant to meet the Target 10 of the Aichi Targets of the Convention of the Biological Diversity.
Original languageEnglish (US)
JournalFrontiers in Marine Science
Volume9
DOIs
StatePublished - May 27 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-06-03
Acknowledged KAUST grant number(s): 3834
Acknowledgements: This work was funded by the Spanish Ministry of Economy, Industry and Competivness with the projects MedShift (CGL2015-71809-P), SumaEco (RTI2018-095441-B-C21) and Clifish (CTM2015-66400-C3-2-R), the European Union’s Horizon 2020 SOCLIMPACT project (grant agreement No 776661) and the King Abdullah University of Science and Technology (KAUST subaward number 3834). SB was supported by a Juan de la Cierva Formación contract funded by the Spanish Ministry of Economy, Industry and Competitiveness. We thank Oscar Serrano for providing the seawater temperature recorded when Amphibolis antarctica die-off was observed at Shark Bay (Australia).

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