Discrete Pulses of Cooler Deep Water Can Decelerate Coral Bleaching During Thermal Stress: Implications for Artificial Upwelling During Heat Stress Events

Sawall, Yvonne; Harris, Moronke; Lebrato, Mario; Wall, Marlene; Feng, Ellias Y.

doi:10.3389/fmars.2020.00720

Cited by 12 publications

(5 citation statements)

References 84 publications

(99 reference statements)

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“…However, although SST products developed offshore and within the open ocean are being applied to the coastal regions, reports exist to inform users to exercise caution when using SST datasets in these coastal regions [ 90 ]. Many upwelling pulses may be localized and of short duration (i.e., lasting for a few hours or days; Duncan et al [ 91 ], Sawall et al [ 92 ]), which may contribute to the higher resolution (MUR and G1SST) products yielding more signals lasting for a longer period when compared to the coarser resolution products (e.g., OISST). Prior investigations for quantifying the durations of upwelling events across the globe have adopted several approaches and estimates derived using various methodologies.…”

Section: Discussionmentioning

confidence: 99%

A novel approach to quantify metrics of upwelling intensity, frequency, and duration

2021

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The importance of coastal upwelling systems is widely recognized. However, several aspects of the current and future behaviors of these systems remain uncertain. Fluctuations in temperature because of anthropogenic climate change are hypothesized to affect upwelling-favorable winds and coastal upwelling is expected to intensify across all Eastern Boundary Upwelling Systems. To better understand how upwelling may change in the future, it is necessary to develop a more rigorous method of quantifying this phenomenon. In this paper, we use SST data and wind data in a novel method of detecting upwelling signals and quantifying metrics of upwelling intensity, duration, and frequency at four sites within the Benguela Upwelling System. We found that indicators of upwelling are uniformly detected across five SST products for each of the four sites and that the duration of those signals is longer in SST products with higher spatial resolutions. Moreover, the high-resolution SST products are significantly more likely to display upwelling signals at 25 km away from the coast when signals were also detected at the coast. Our findings promote the viability of using SST and wind time series data to detect upwelling signals within coastal upwelling systems. We highlight the importance of high-resolution data products to improve the reliability of such estimates. This study represents an important step towards the development of an objective method for describing the behavior of coastal upwelling systems.

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Section: Discussionmentioning

confidence: 99%

A novel approach to quantify metrics of upwelling intensity, frequency, and duration

2021

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“…Coral reefs are frequently exposed to these local episodes, especially to upwellings, as seen in the Great Barrier Reef (Andrews and Gentien, 1982), Central Pacific islands (Kelly et al, 2014), Pacific coast of Central America (D'Croz and O'Dea, 2007), Florida Keys (Leichter et al, 1996), Caribbean (Diaz-Pulido and Garzon-Ferreira, 2002) and Seychelles (Novozhilov et al, 1992). Although cooling events can be beneficial to corals during periods of increased SST by creating thermal refuges and reducing bleaching intensity (Glynn, 1996;Riegl and Piller, 2003;West and Salm, 2003;Riegl et al, 2019;Johnson et al, 2020;Sawall et al, 2020;Storlazzi et al, 2020), this is not always the case. For example, around the northern island of the Galapagos reefs, internal waves, forcing cool water upwards above the thermocline, led to a 12°C drop in temperature over a 6-day period, and induced coral bleaching and mortality (Banks et al, 2009;Glynn et al, 2017a,b).…”

Section: Introductionmentioning

confidence: 99%

Symbiont regulation in Stylophora pistillata during cold stress: an acclimation mechanism against oxidative stress and severe bleaching

Marangoni

Rottier

Ferrier‐Pagés

2021

Journal of Experimental Biology

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Widespread coral bleaching and mortality, leading to coral reef decline, have been mainly associated with climate change driven increases in sea surface temperature (SST). However, bleaching and mortality events have also been related to decreases in SST, with cold stress events (e.g. La Niña events) being expected to increase in frequency or intensity due to a changing climate. Cold stress creates similar physiological symptoms in symbiotic reef building corals to those observed when they are heat stressed, and the biochemical mechanisms underpinning cold stress in corals have been suggested to be related to an oxidative stress condition. However, up to now, this hypothesis has not been tested. This study assessed how short and long cold excursions in seawater temperature affect the physiology and biochemical processes related to oxidative stress in the reef-building coral Stylophora pistillata. We provide for the first time direct evidence that the mechanisms underpinning cold stress and bleaching are related to the production of reactive oxygen species (ROS), and that rapid expulsion of a significant proportion of the symbiont population by the host during cooling conditions is an acclimation mechanism to avoid oxidative stress, and ultimately severe bleaching. Furthermore, this study is one of the first to show that upwelling conditions (short term cold stress+nutrient enrichment) can provoke a more severe oxidative stress condition in corals than cold stress alone.

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“…In this regard, performing a medium to longterm experiment with focus on analyzing heat-stressed corals' physiological response to cool subthermocline water analogous to AU, can be a meaningful attempt. This can provide important insights for how AU can be operated to provide stress relief while reducing side effects (Sawall et al, 2020), and suggest further refined set-ups for modeling studies. Current technology would theoretically allow successful installation and operation of AU devices locally in shallow coral reef environment.…”

Section: Discussionmentioning

confidence: 99%

Modeling Coral Bleaching Mitigation Potential of Water Vertical Translocation – An Analogue to Geoengineered Artificial Upwelling

et al. 2020

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Artificial upwelling (AU) is a novel geoengineering technology that brings seawater from the deep ocean to the surface. Within the context of global warming, AU techniques are proposed to reduce sea surface temperature at times of thermal stress around coral reefs. A computationally fast but coarse 3D Earth System model (3.6° longitude × 1.8° latitude) was used to investigate the environmental impacts of hypothetically implemented AU strategies in the Great Barrier Reef, South China Sea, and Hawaiian regions. While omitting the discussion on sub-grid hydrology, we simulated in our model a water translocation from either 130 or 550 m depth to sea surface at rates of 1 or 50 m3 s–1 as analogs to AU implementation. Under the Representative Concentration Pathway 8.5 emissions scenario from year 2020 on, the model predicted a prevention of coral bleaching until the year 2099 when AU was implemented, except under the least intense AU scenario (water from 130 m depth at 1 m3 s–1). Yet, intense AU implementation (water from 550 m depth at 50 m3 s–1) will likely have adverse effects on coral reefs by overcooling the surface water, altering salinity, decreasing calcium carbonate saturation, and considerably increasing nutrient levels. Our result suggests that if we utilize AU for mitigating coral bleaching during heat stress, AU implementation needs to be carefully designed with respect to AU’s location, depth, intensity and duration so that undesirable environmental effects are minimized. Following a proper installation and management procedure, however, AU has the potential to decelerate destructive bleaching events and buy corals more time to adjust to climate change.

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Discrete Pulses of Cooler Deep Water Can Decelerate Coral Bleaching During Thermal Stress: Implications for Artificial Upwelling During Heat Stress Events

Cited by 12 publications

References 84 publications

A novel approach to quantify metrics of upwelling intensity, frequency, and duration

A novel approach to quantify metrics of upwelling intensity, frequency, and duration

Symbiont regulation in Stylophora pistillata during cold stress: an acclimation mechanism against oxidative stress and severe bleaching

Modeling Coral Bleaching Mitigation Potential of Water Vertical Translocation – An Analogue to Geoengineered Artificial Upwelling

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