Large-amplitude internal waves sustain coral health during thermal stress

Schmidt, Gertraud M.; Wall, Marlene; Taylor, Marc H; Jantzen, Carin; Richter, Claudio

doi:10.1007/s00338-016-1450-z

Cited by 40 publications

(34 citation statements)

References 50 publications

(88 reference statements)

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“…The response of the benthic community was unusually rapid. Whereas corals typically bleach – and recover – in response to several months of accumulated heating or cooling2829, corals on the Dongsha reef flat bleached within one week of peak temperatures and 90% of them were either recovered or dead less than six weeks later.…”

Section: Resultsmentioning

confidence: 99%

Mass coral mortality under local amplification of 2 °C ocean warming

DeCarlo

Cohen

Wong

et al. 2017

Sci Rep

104

112

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A 2 °C increase in global temperature above pre-industrial levels is considered a reasonable target for avoiding the most devastating impacts of anthropogenic climate change. In June 2015, sea surface temperature (SST) of the South China Sea (SCS) increased by 2 °C in response to the developing Pacific El Niño. On its own, this moderate, short-lived warming was unlikely to cause widespread damage to coral reefs in the region, and the coral reef “Bleaching Alert” alarm was not raised. However, on Dongsha Atoll, in the northern SCS, unusually weak winds created low-flow conditions that amplified the 2 °C basin-scale anomaly. Water temperatures on the reef flat, normally indistinguishable from open-ocean SST, exceeded 6 °C above normal summertime levels. Mass coral bleaching quickly ensued, killing 40% of the resident coral community in an event unprecedented in at least the past 40 years. Our findings highlight the risks of 2 °C ocean warming to coral reef ecosystems when global and local processes align to drive intense heating, with devastating consequences.

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Section: Resultsmentioning

confidence: 99%

Mass coral mortality under local amplification of 2 °C ocean warming

DeCarlo

Cohen

Wong

et al. 2017

Sci Rep

104

112

View full text Add to dashboard Cite

show abstract

“…During warm water events, breaking IGWs can also entrain or mix cooler water into the reef environment. This process reduces heat stress and coral bleaching (Schmidt et al, 2016(Schmidt et al, , 2017Wall et al, 2015), and the associated rapid temperature fluctuations have been shown to condition corals to be more resilient to heat stress (Buerger et al, 2015;Safaie et al, 2018). Areas of intense wave activity thus may be associated with the creation of so-called "thermal refugia" for coral reefs, and because the tides and their attendant IGW generation are not affected by climate change, these refugia may be expected to persist into the future.…”

Section: Introductionmentioning

confidence: 99%

Particle‐Based Lagrangian Filtering for Locating Wave‐Generated Thermal Refugia for Coral Reefs

et al. 2020

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Tides and tidally generated waves play a key role in modulating the heat budget of the nearshore environment, which can significantly affect the ecology of the coastal and reef zones. The high spatial resolution required to resolve such waves in numerical models means that diagnosing wave‐generated heat fluxes (WHFs) has so far only been possible over very limited areas. Because many marine ecosystems that are affected by WHFs, such as coral reefs, are patchily distributed within domains of hundreds of kilometers, an alternative to fully wave‐resolving models is needed to identify thermal refugia and guide conservation efforts over larger regions. In this study, a one‐way nested series of regional ocean simulations has been conducted to study the role of waves in driving high‐frequency temperature variations in the Coral Triangle and to develop a method for identifying WHF in coarser‐resolution models. A filtering method using Lagrangian particles is used to separate the wave component of the flow, which is used to diagnose the wave energy and to identify locations experiencing large, high‐frequency temperature variability. These locations are shown to possess three key characteristics: large time‐mean wave kinetic energy, shallow depth, and a steep bathymetric gradient that gives access to a nearby source of cold, subthermocline water. A function of the wave kinetic energy and bathymetric slope is found to closely correlate with areas of maximal temperature variance, suggesting its use as a convenient and readily calculable metric to locate thermal refugia in observations or numerical experiments over large spatial domains.

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“…The response of the benthic community was exceptionally fast. Whereas corals typically bleach -and recover -in response to several months of accumulated heating or cooling (Liu et al, 2014;Schmidt et al, 2016), corals on the Dongsha reef flat bleached within 1 week of peak temperatures and 90% of them were either recovered or dead less than 6 weeks later.…”

Section: Resultsmentioning

confidence: 99%

Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change

DeCarlo¹

2017

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Scleractinian corals extract calcium (Ca 2+ ) and carbonate (CO 2−3 ) ions from seawater to construct their calcium carbonate (CaCO 3 ) skeletons. Key to the coral biomineralization process is the active elevation of the CO 2− 3 concentration of the calcifying fluid to achieve rapid nucleation and growth of CaCO 3 crystals. Coral skeletons contain valuable records of past climate variability and contribute to the formation of coral reefs. However, limitations in our understanding of coral biomineralization hinder the accuracy of (1) coral-based reconstructions of past climate, and (2) predictions of coral reef futures as anthropogenic CO 2 emissions drive declines in seawater CO 2− 3 concentration.In this thesis, I investigate the mechanism of coral biomineralization and evaluate the sensitivity of coral reef CaCO 3 production to seawater carbonate chemistry. First, I conducted abiogenic CaCO 3 precipitation experiments that identified the U/Ca ratio as a proxy for fluid CO 2− 3 concentration. Based on these experimental results, I developed a quantitative coral biomineralization model that predicts temperature can be reconstructed from coral skeletons by combining Sr/Ca -which is sensitive to both temperature and CO 2− 3-with U/Ca into a new proxy called "Sr-U". I tested this prediction with 14 corals from the Pacific Ocean and the Red Sea spanning mean annual temperatures of 25.7-30.1 ∘ C and found that Sr-U has uncertainty of only 0.5 ∘ C, twice as accurate as conventional coral-based thermometers. Second, I investigated the processes that differentiate reef-water and open-ocean carbonate chemistry, and the sensitivity of ecosystem-scale calcification to these changes. On Dongsha Atoll in the northern South China Sea, metabolic activity of resident organisms elevates reef-water CO 2− 3 twice as high as the surrounding open ocean, driving rates of ecosystem calcification higher than any other coral reef studied to date. When high temperatures stressed the resident coral community, metabolic activity slowed, with dramatic effects on reef-water chemistry and ecosystem calcification. Overall, my thesis highlights how the modulation of CO 2− 3 , by benthic communities on the reef and individual coral polyps in the colony, controls the sensitivity of coral reefs to future ocean acidification and influences the climate records contained in the skeleton.

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Large-amplitude internal waves sustain coral health during thermal stress

Cited by 40 publications

References 50 publications

Mass coral mortality under local amplification of 2 °C ocean warming

Mass coral mortality under local amplification of 2 °C ocean warming

Particle‐Based Lagrangian Filtering for Locating Wave‐Generated Thermal Refugia for Coral Reefs

Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change

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