Nutrient-supplying ocean currents modulate coral bleaching susceptibility

With predictions that mass coral bleaching will occur annually within this century, conservation efforts must focus their limited resources based on an accurate understanding of the drivers of bleaching. Here, we provide spatial and temporal evidence that excess nutrients exacerbate the detrimental effects of heat stress to spark mass coral bleaching in the Red Sea. Exploiting this region’s unique oceanographic regime, where nutrients and heat stress vary independently, we demonstrate that the world’s third largest coral reef system historically suffered from severe mass bleaching only when exposed to both unusually high temperature and nutrients. Incorporating nutrient-supplying ocean currents and their variability into coral bleaching forecasts will be critical for effectively guiding efforts to safeguard the reefs most likely to persist in the Anthropocene.

Citation

DeCarlo, T. M., Gajdzik, L., Ellis, J., Coker, D. J., Roberts, M. B., Hammerman, N. M., … Berumen, M. L. (2020). Nutrient-supplying ocean currents modulate coral bleaching susceptibility. Science Advances, 6(34), eabc5493. doi:10.1126/sciadv.abc5493

Acknowledgements

We thank L. Tanabe, S. Brown, A. Dunne, and T. Terraneo for assistance with field and laboratory aspects of this study; Dream Divers for logistical support; and A. Green for insightful discussions.
Support was provided by the King Abdullah University of Science and Technology (KAUST) (Red Sea Research Center funding to M.L.B. and B. H. Jones, as well as baseline research funds to M.L.B.). Seawater sampling in 2011 was conducted under a Woods Hole Oceanographic Institution (WHOI)/KAUST collaboration.