Global warming is killing corals; however, the effects of warming on population connectivity, a process fundamental to reef recovery, are largely unexplored. Using a high-resolution (as high as 200 m), empirically calibrated biophysical model of coral larval dispersal for the southern Great Barrier Reef, we show that the increased larval mortality and reduced competency duration under a 2 °C warming alter dispersal patterns, whereas projected changes in large-scale currents have limited effects. Overall, there was on average a 7% decrease in the distance larvae disperse (among-reef interquartile range (IQR), −10% to −4%), an 8% decrease in the number of connections into each reef (IQR, −11% to −3%) and a 20% increase in local retention (IQR, 0% to +49%). Collectively, these shifts imply that 2 °C of warming will reduce inter-reef connectivity, hampering recovery after disturbances and reducing the spread of warm-adapted genes. Such changes make protections more effective locally, but may require reducing spacing between protected areas.
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Yearly connectivity matrices and the processed data used to construct Figs. 1a–e and 2 are available at https://doi.org/10.5061/dryad.4f4qrfjbk. Larval survival and competency is provided in the Appendix 1 (Supplementary Fig. 1) and can be obtained from the authors on request.
The SLIM model source code can be found at https://git.immc.ucl.ac.be/dg/dg. Larval dynamics modelling is provided in the Appendix 1, and references therein, and can be obtained from the authors on request.
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Major funding for this research was provided by the Australian Research Council (DP110101168) (J.F., A.H.B.), a Queensland Government Smart Futures Fellowship (J.F.), the Australian Research Council’s Centre of Excellence for Coral Reef Studies (A.H.B., S.R.C.), Federation Wallonie-Bruxelles ARC grant 10/15-028 (C.J.T.), the Belgian Fund for Scientific Research (FRS-FNRS) (J.L.), and Université catholique de Louvain, Belgium (E.H., E.D., J.L.). High-performance computing resources were provided by the Université catholique de Louvain (CISM/UCL) and the Consortium des Équipements de Calcul Intensif en Fédération Wallonie-Bruxelles (CÉCI) funded by the FRS-FNRS under grant number 2.5020.11 and by the Walloon Region.
The authors declare no competing interests.
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Figueiredo, J., Thomas, C.J., Deleersnijder, E. et al. Global warming decreases connectivity among coral populations. Nat. Clim. Chang. 12, 83–87 (2022). https://doi.org/10.1038/s41558-021-01248-7