[Coral-List] New publication on internal tides and coral bleaching globally

Cheriton, Olivia ocheriton at usgs.gov
Tue Aug 11 17:33:03 UTC 2020

Dear colleagues,

Tidal flushing of coral reefs with cooler, deep ocean water can reduce thermal stress that causes coral bleaching. The USGS, NOAA, and academia conducted a study that incorporates tidally-induced water temperature fluctuations at depth into coral bleaching models to improve projections. The paper presents the first global maps of these cooling effects that can provide thermal refugia by buffering some coral reefs from future global warming and how they vary for different global emission scenarios. These results can aid the decision-making process of resource managers designating MPAs to protect corals in the face of climate change.

Please find a link to this new, open-access paper here: https://rdcu.be/b6aMH


Observations show ocean temperatures are rising due to climate change, resulting in a 5-fold increase in the incidence of regional-scale coral bleaching events since the 1980s; analyses based on global climate models forecast bleaching will become an annual event for most of the world’s coral reefs within 30-50 yr. Internal waves at tidal frequencies can regularly flush reefs with cooler waters, buffering the thermal stress from rising sea-surface temperatures. Here we present the first global maps of the effects these processes have on bleaching projections for three IPCC-AR5 emissions scenarios. Incorporating semidiurnal temperature fluctuations into the projected water temperatures at depth creates a delay in the timing of annual severe bleaching ≥10 yr (≥20 yr) for 38% (9%), 15% (1%), and 1% (0%) of coral reef sites for the low, moderate, and high emission scenarios, respectively; regional averages can reach twice as high. These cooling effects are greatest later in 21st century for the moderate emission scenarios, and around the middle 21st century for the highest emission scenario. Our results demonstrate how these effects could delay bleaching for corals, providing thermal refugia. Identification of such areas could be a factor for the selection of coral reef marine protected areas.


Storlazzi, C.D., Cheriton O.M., van Hooidonk, R., Zhao, Z., and Brainard, R.E., 2020. “Internal tides can provide thermal refugia to coral reefs facing global warming” Nature-Scientific Reports, 10:13435, doi: 10.1038/s41598-020-70372-9

Olivia M. Cheriton, PhD

U.S. Geological Survey
Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA 95060

Office: 831-460-7579
Fax: 831-427-4748

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