Increasing Coral Reef Resilience Through Successive Marine Heatwaves

Fox, Michael D.; Cohen, Anne L.; Rotjan, Randi D.; Mangubhai, Sangeeta; Sandin, Stuart A.; Smith, Jennifer E.; Thorrold, Simon R.; Dissly, Laura; Mollica, Nathan R.; Obura, David

doi:10.1029/2021gl094128

Cited by 29 publications

(26 citation statements)

References 50 publications

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“…Changes in bleaching susceptibility in response to previous stress exposures were also reported from other regions across the globe, particularly after recurrent bleaching events (Pratchett et al 2013;Hughes et al 2019;Fisch et al 2019;Gintert et al 2018;Fox et al 2021;Guest et al 2012). The bleaching severity of three major coral genera (Acropora, Pocillopora, and Porites) in the Great Barrier Reef (GBR) was reported to be much lower than expected during the 2002 bleaching despite higher and longer temperature stress compared to the previous 1998 bleaching event.…”

Section: Acquired Tolerance In Adult Coralsmentioning

confidence: 73%

Epigenetics and Acquired Tolerance to Environmental Stress

Aranda

2022

Coral Reefs of the World

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The unprecedented rate of increase in global temperatures is threatening to outpace the evolutionary adaptability of corals. With climate change endangering the very existence of coral reefs, the ability of corals to mitigate detrimental changes in their environment within their lifetime is becoming more critical than ever. A range of experiments and observations suggest that corals might be able to retain environmental memory from previous stress that provides increased resilience to recurrent events, and examples from other organisms suggest that such responses could potentially be transferred across generations. However, the underlying molecular mechanisms and the extent to which they can improve resilience and survivability in light of climate change have yet to be elucidated. This chapter provides an overview of the current knowledge on acquired tolerance to environmental stress in corals and the potential role of epigenetic mechanisms in this process. Based on the current evidence from corals and other organisms, I provide a theoretical model by which epigenetic mechanisms could confer transcriptional memory and, thus, promote acquired tolerance in these organisms.

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Section: Acquired Tolerance In Adult Coralsmentioning

confidence: 73%

Epigenetics and Acquired Tolerance to Environmental Stress

Aranda

2022

Coral Reefs of the World

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“…By extension, the absence of these coral-rich, uninhabited islands from this analysis may influence our finding of no difference in reef builder cover between inhabited and uninhabited islands. However, a recent study by Fox et al (2021) reported mean coral cover of <20% in 2018 from three of these uninhabited Phoenix Islands present in the Smith et al (2016) study. Thus, recent coral cover at uninhabited reefs of the Phoenix Islands seem to align with observed values reported here in the U.S.-affiliated islands and atolls in the central Pacific, suggesting that these reefs are not insulated from coral loss.…”

Section: Discussionmentioning

confidence: 84%

Oceanic productivity and high-frequency temperature variability—not human habitation—supports calcifier abundance on central Pacific coral reefs

et al. 2022

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Past research has demonstrated how local-scale human impacts—including reduced water quality, overfishing, and eutrophication—adversely affect coral reefs. More recently, global-scale shifts in ocean conditions arising from climate change have been shown to impact coral reefs. Here, we surveyed benthic reef communities at 34 U.S.-affiliated Pacific islands spanning a gradient of oceanic productivity, temperature, and human habitation. We re-evaluated patterns reported for these islands from the early 2000s in which uninhabited reefs were dominated by calcifiers (coral and crustose coralline algae) and thought to be more resilient to global change. Using contemporary data collected nearly two decades later, our analyses indicate this projection was not realized. Calcifiers are no longer the dominant benthic group at uninhabited islands. Calcifier coverage now averages 26.9% ± 3.9 SE on uninhabited islands (compared to 45.18% in the early 2000s). We then asked whether oceanic productivity, past sea surface temperatures (SST), or acute heat stress supersede the impacts of human habitation on benthic cover. Indeed, we found variation in benthic cover was best explained not by human population densities, but by remotely sensed metrics of chlorophyll-a, SST, and island-scale estimates of herbivorous fish biomass. Specifically, higher coral and CCA cover was observed in more productive waters with greater biomass of herbivores, while turf cover increased with daily SST variability and reduced herbivore biomass. Interestingly, coral cover was positively correlated with daily variation in SST but negatively correlated with monthly variation. Surprisingly, metrics of acute heat stress were not correlated with benthic cover. Our results reveal that human habitation is no longer a primary correlate of calcifier cover on central Pacific island reefs, and highlight the addition of oceanic productivity and high-frequency SST variability to the list of factors supporting reef builder abundance.

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“…However, coral thermal stress tolerance varies widely and can be influenced by the temperature regimes of specific locations (Morikawa and Palumbi, 2019;Cornwell et al, 2021;Logan et al, 2021). Selective mortality through successive heatwaves may shape coral responses to subsequent warming events (Fox et al, 2021) where repeated heatwaves may improve the 'ecological memory' of corals to further enhance thermal tolerance for future climate projections (Hackerott et al, 2021). Consequently, reconciling spatial patterns of coral thermal tolerance and their associated drivers is critical for improving projections of coral survival in the future.…”

Section: Introductionmentioning

confidence: 99%

Appraisal of coral bleaching thresholds and thermal projections for the northern Red Sea refugia

et al. 2022

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Corals in the northern Red Sea exhibit high thermal tolerance despite the increasing heat stress. It is assumed that corals throughout the Red Sea have similar bleaching thresholds (32°C or higher), and hence greater bleaching tolerance of corals in the northern Red Sea region is likely due to lower ambient water temperatures (25–28°C) that remain well below the corals’ physiological maxima. Whether bleaching patterns across the Red Sea are independent of the local maximum monthly mean of seawater temperature and aligned with an assumed 32°C threshold has yet to be determined. Here, we used remotely sensed surface sea temperature data spanning 1982–2020 to model spatial distributions of Degree Heat Weeks across the Red Sea in relation to assumed coral thermal threshold values of 30, 31, and 32°C. We also used the Coupled Model Intercomparison Project Phase 5 model outputs to predict warming trends in the Red Sea under different greenhouse gas representative concentration pathways (RCPs). We show that applying 32°C thresholds dramatically reduces effective Degree Heat Weeks in the north, but not in central or southern Red Sea regions, a finding that is consistent with historical bleaching observations throughout the Red Sea. Further, model predictions under the most extreme RCP8.5 scenario exhibited ~3°C warming by the end of the 21st century (1998-2020) throughout the Red Sea with less pronounced warming for the northern Red Sea (2–2.5°C) compared to the central and southern regions (2.7–3.1°C). This warming rate will remain below the assumed thermal threshold for the northern Red Sea which should help this region to serve as refugia (i.e., maintaining favorable temperatures) for corals to persist for decades ahead. Together, our results support the notion that corals have similar thresholds throughout the Red Sea; hence, coral bleaching thresholds are independent of the local maximum monthly mean. Consequently, where regional warming projections suggest the northern Red Sea will not reach assumed bleaching thresholds (32°C) before the end of the 21st century, coral reefs in the northern region may be among the last standing against climate change.

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Increasing Coral Reef Resilience Through Successive Marine Heatwaves

Cited by 29 publications

References 50 publications

Epigenetics and Acquired Tolerance to Environmental Stress

Epigenetics and Acquired Tolerance to Environmental Stress

Oceanic productivity and high-frequency temperature variability—not human habitation—supports calcifier abundance on central Pacific coral reefs

Appraisal of coral bleaching thresholds and thermal projections for the northern Red Sea refugia

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