Ocean warming threatens the provisioning of coral reef ecosystem services through the increasing frequency and intensity of coral bleaching and associated mortality events. Here, we quantified sea surface temperature warming trends and maximum annual degree heating weeks (DHW) from the NOAA Coral Reef Watch CoralTemp station-level data for Puerto Rico (1985–2023) and paired this with a review of coral bleaching observations to inform management and restoration efforts. Every region in Puerto Rico warmed at rates surpassing the hypothesized 0.10° C per decade rate of coral adaptation and acclimatization, with warming rates increasing from 0.154 ± 0.005° C per decade in the west to 0.215 ± 0.006° C per decade in the east. Ecologically significant (DHW ≥ 4) or severe (DHW ≥ 8) coral bleaching heat stress events were observed in 2005–2006, 2010, 2019, and 2023, but varied in intensity between regions with consistently lower heat stress in the west. We found coral bleaching observations for 50% of years since 1969, but many observations lacked quantitative information and/or were biased towards the major areas of reef development. The National Coral Reef Monitoring Program island-wide stratified random sampling recorded moderate and/or severe coral bleaching at multiple sites in 2019 and 2021, but not for 2014 or 2016/2017. While regional variability in warming rates, heat stress, and climate model projections provide some indications for increased climate resilience in the west, coral bleaching observations and previous resilience assessments highlight the importance of local-scale variability. Climate models nonetheless project annual severe bleaching (DHW ≥ 8) across Puerto Rico by 2022 ± 5 under the very high greenhouse gas emissions scenario.
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15 May 2024
Ocean Warming, Heat Stress, and Coral Bleaching in Puerto Rico
Carla L. Mejias-Rivera,
Travis A. Courtney
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Caribbean Journal of Science
Vol. 54 • No. 1
July 2024
Vol. 54 • No. 1
July 2024