Marine Heatwaves

Oliver, Eric C. J.; Benthuysen, Jessica A.; Darmaraki, Sofia; Donat, Markus G.; Hobday, Alistair J.; Holbrook, Neil J.; Schlegel, Robert W.; Gupta, Alex Sen

doi:10.1146/annurev-marine-032720-095144

Cited by 293 publications

(211 citation statements)

References 117 publications

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“…Gaining a more complete understanding of environmental history and legacy effects in ameliorating or exacerbating coral bleaching is vital as marine heatwaves intensify (Oliver et al., 2018, 2021). At our study sites, the fringing reef habitat of Lilipuna, with close proximity to shore and silt‐dominated backreef benthos, contrasts the patch reef pinnacle of Reef 14 in the middle of the Kāne'ohe Bay lagoon.…”

Section: Discussionmentioning

confidence: 99%

Shifting baselines: Physiological legacies contribute to the response of reef corals to frequent heatwaves

et al. 2021

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Global climate change is altering coral reef ecosystems. Notably, marine heatwaves are producing widespread coral bleaching events that are increasing in frequency, with projections for annual bleaching events on reefs worldwide by mid‐century. Responses of corals to elevated seawater temperatures are modulated by abiotic factors (e.g. environmental regimes) and dominant Symbiodiniaceae endosymbionts that can shift coral traits and contribute to physiological legacy effects on future response trajectories. It is critical, therefore, to characterize shifting physiological and cellular states driven by these factors and evaluate their influence on in situ bleaching (and recovery) events. We use back‐to‐back bleaching events (2014, 2015) in Hawai'i to characterize the cellular and organismal phenotypes of Montipora capitata corals dominated by heat‐sensitive Cladocopium or heat‐tolerant Durusdinium Symbiodiniaceae at two reef sites. Despite fewer degree heating weeks in the first‐bleaching event relative to the second (7 vs. 10), M. capitata bleaching severity was greater [bleached cover: ~70% (2014) vs. 50% (2015)] and environmental history (site effects) on coral phenotypes were more pronounced. Symbiodiniaceae affected bleaching responses, but immunity and antioxidant activity was similar in all corals, despite differences in bleaching phenotypes. We demonstrate that repeat bleaching triggers cellular responses that shift holobiont multivariate phenotypes. These perturbed multivariate phenotypes constitute physiological legacies, which set corals on trajectories (positive and/or negative) that influence future coral performance. Collectively, our data support the need for greater tracking of stress response in a multivariate context to better understand the biology and ecology of corals in the Anthropocene. A free Plain Language Summary can be found within the Supporting Information of this article.

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Section: Discussionmentioning

confidence: 99%

Shifting baselines: Physiological legacies contribute to the response of reef corals to frequent heatwaves

et al. 2021

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“…Moreover, North Atlantic Oscillation (NAO) also shown to play an important role in modulating SST of the Indian ocean in interannual to decadal time scale (Xie et al, 2021). Therefore, these climate modes can support the genesis or suppression of heatwaves depending upon their phases via modulating the thermocline depth and associated air-sea interactions of the basin (Hobrook et al, 2019(Hobrook et al, , 2020Oliver et al, 2021).…”

Section: Role Of Dominant Climate Modesmentioning

confidence: 99%

“…Owing to their devastating nature, MHWs and it's generating mechanisms received a lot of attention in the recent decade. Studies of major MHWs that appeared in various parts of the world over the last decade suggest that evolution and the forcing mechanisms of such events vary considerably from region to region and predominantly depend on the local air-sea coupling, atmospheric conditions, oceanic preconditions and remote climatic teleconnections (Holbrook et al, 2019;Oliver et al, 2021). For example, persistent large scale positive atmospheric pressure anomaly ridge caused unprecedented warm SST in the northeastern Pacific during 2013-2016 with anomalies exceeding more than 3 o C (Bond et al, 2015;Lorenzo and Mantua, 2016).…”

Section: Introductionmentioning

confidence: 99%

Marine Heatwaves in the Arabian Sea

Chatterjee

Anil

Shenoy

2021

Preprint

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Abstract. Marine heatwaves (MHWs) are prolonged warm sea condition events that cause a destructive impact on marine ecosystems. The documentation of MHWs and assessment of their impacts are largely confined to a few regional seas or in global mean studies. The Indian Ocean received almost no attention in this regard despite the fact that this ocean basin, particularly the Arabian Sea, is warming at the most rapid pace among the other tropical basins in recent decades. This study shows the characteristics MHWs for the Arabian Sea during 1982–2019. Our analysis shows that the duration of MHWs exhibit a rapidly increasing trend of ~20 days/decade (1.5–2 count/decade) in the northern Arabian Sea and in the southeastern Arabian Sea close to the west coast of India; which is more than 15 fold increase in the MHW days from the early 80s'. At the same time increase in MHW frequency is ~1.5–2 count/decade i.e an increase of ~6 fold, indicating more frequent and much longer heatwave events in the recent decade. Notably, since the beginning of the satellite record, the year 2010 and 2016 saw the maximum number of heatwave days with more than 75 % of days of the pre-monsoon and summer monsoon season experienced heatwaves. The accelerated trend of the heatwave days is found to be driven by the rapid rise of the mean SST of the Arabian Sea in the recent decade. Moreover, longer heatwave days are also associated with the dominant climate modes and among them, Indian Ocean Basin mode via the decaying phase of the El-Niño is found to be the most influencing mode contributing in more than 70–80 % of observed heatwave days in this basin. Mixed layer heat budget analysis suggests significant heterogeneity in the dominant processes across the years; however, weakening of latent heat loss is in general one of the key mechanism in the genesis of most of the MHWs.

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“…Previous studies have identified drivers of MHWs (e.g., Holbrook et al, 2019) and of chlorophyll variability (Boyce et al, 2010;McClain, 2009;Wilson and Adamec, 2002) separately, but it is currently unknown what the underlying drivers of compound MHW and lowchlorophyll (LChl) events are . Global warming is the dominant driver of long-term changes in MHW frequency Oliver, 2019). Yet, natural variability of the climate system also creates situations that favor the occurrence of extreme events.…”

Section: Introductionmentioning

confidence: 99%

Compound high-temperature and low-chlorophyll extremes in the ocean over the satellite period

et al. 2021

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Abstract. Extreme events in the ocean severely impact marine organisms and ecosystems. Of particular concern are compound events, i.e., when conditions are extreme for multiple potential ocean ecosystem stressors such as temperature and chlorophyll. Yet, little is known about the occurrence, intensity, and duration of such compound high-temperature (a.k.a. marine heatwaves – MHWs) and low-chlorophyll (LChl) extreme events, whether their distributions have changed in the past decades, and what the potential drivers are. Here we use satellite-based sea surface temperature and chlorophyll concentration estimates to provide a first assessment of such compound extreme events. We reveal hotspots of compound MHW and LChl events in the equatorial Pacific, along the boundaries of the subtropical gyres, in the northern Indian Ocean, and around Antarctica. In these regions, compound events that typically last 1 week occur 3 to 7 times more often than expected under the assumption of independence between MHWs and LChl events. The occurrence of compound MHW and LChl events varies on seasonal to interannual timescales. At the seasonal timescale, most compound events occur in summer in both hemispheres. At the interannual timescale, the frequency of compound MHW and LChl events is strongly modulated by large-scale modes of natural climate variability such as the El Niño–Southern Oscillation, whose positive phase is associated with increased compound event occurrence in the eastern equatorial Pacific and in the Indian Ocean by a factor of up to 4. Our results provide a first understanding of where, when, and why compound MHW and LChl events occur. Further studies are needed to identify the exact physical and biological drivers of these potentially harmful events in the ocean and their evolution under global warming.

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Marine Heatwaves

Cited by 293 publications

References 117 publications

Shifting baselines: Physiological legacies contribute to the response of reef corals to frequent heatwaves

Shifting baselines: Physiological legacies contribute to the response of reef corals to frequent heatwaves

Marine Heatwaves in the Arabian Sea

Compound high-temperature and low-chlorophyll extremes in the ocean over the satellite period

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