Coral reefs as a source of climate-active aerosols

Jackson, Rebecca; Gabric, Albert Jerome; Cropp, Roger Allan

doi:10.7717/peerj.10023

Cited by 2 publications

(3 citation statements)

References 176 publications

(241 reference statements)

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“…Coral reefs have themselves been suggested to contribute to local ocean thermal regulation because many classes of unicellular marine algae, including those related to coral reefs, produce considerable amounts of dimethyl sulphide (DMS), a compound known to serve as cloud condensation nuclei and contribute to marine cloud formation (Jackson et al, 2020). A study on the GBR found that periods of low‐level cloudiness coincided with high local DMS flux, had a negative feedback on SSTs, and limited coral bleaching; conversely very low local DMS flux from bleached reef areas coincided with SST anomalies of up to 3°C (Jones et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Cloudiness reduces the bleaching response of coral reefs exposed to heat stress

González‐Espinosa

Donner

2021

Global Change Biology

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Climate change and warming ocean temperatures are a threat to coral reef ecosystems. Since the 1980s, there has been an increase in mass coral bleaching and associated coral mortality due to more frequent and severe thermal stress. Although most research has focused on the role of temperature, coral bleaching is a product of the interacting effects of temperature and other environmental variables such as solar radiation. High light exacerbates the effects of thermal stress on corals, whereas reductions in light can reduce sensitivity to thermal stress. Here, we use an updated global dataset of coral bleaching observations (n = 35,769) from 1985 to 2017 and satellite‐derived datasets of SST and clouds to examine for the first time at a global scale the influence of cloudiness on the likelihood of bleaching from thermal stress. We find that among coral reefs exposed to severe bleaching‐level heat stress (Degree Heating Weeks >8°Cˑweek), bleaching severity is inversely correlated with the interaction of heat stress and cloud fraction anomalies (p < 0.05), such that higher cloudiness implies reduced bleaching response. A Random Forest model analysis employing different set of environmental variables shows that a model employing Degree Heating Weeks and the 30‐day cloud fraction anomaly most accurately predicts bleaching severity (Accuracy = 0.834; Cohen's Kappa = 0.769). Based on these results and global warm‐season cloudiness patterns, we develop a ‘cloudy refugia’ index which identifies the central equatorial Pacific and French Polynesia as regions where cloudiness is most likely to protect corals from bleaching. Our findings suggest that incorporating cloudiness into prediction models can help delineate bleaching responses and identify reefs which may be more resilient to climate change.

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Section: Discussionmentioning

confidence: 99%

Cloudiness reduces the bleaching response of coral reefs exposed to heat stress

González‐Espinosa

Donner

2021

Global Change Biology

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“…Coral reefs provide key ecosystem services: biodiversity, coastal protection, biogeochemical cycling, fisheries, provision of raw materials, and cultural benefits (Woodhead et al, 2019). Recently, an ecosystem service of short-term regulation of regional climate has been suggested too, at least for the large extending Great Barrier Reef (Jones, 2015;Jackson et al, 2020). This climate effect would operate from the observed capacity of coral reefs to emit volatile sulfur in the form of dimethylsulfide (DMS).…”

Section: Introductionmentioning

confidence: 99%

“…In the atmosphere, emitted DMS oxidizes to form precursors of aerosols that enhance the formation, lifetime, and brightness of low-level clouds (Charlson et al, 1987;Simo, 2001), and thereby potentially reduce incident solar irradiance and temperature. Since the production and emission of DMS from coral reefs is triggered under higher irradiance and temperature, this reef-atmosphere interaction could potentially act as a regional thermostat (Jackson et al, 2020). This hypothesis is currently under scrutiny.…”

Section: Introductionmentioning

confidence: 99%

Spatial and diel patterns of volatile organic compounds, DMSP-derived compounds, and planktonic microorganisms around a tropical scleractinian coral colony

Masdeu-Navarro

Mangot²,

Xue³

et al. 2022

Front. Mar. Sci.

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Volatile organic compounds (VOCs) are constituents of marine ecosystems including coral reefs, where they are sources of atmospheric reactivity, indicators of ecosystem state, components of defense strategies, and infochemicals. Most VOCs result from sunlight-related processes; however, their light-driven dynamics are still poorly understood. We studied the spatial variability of a suite of VOCs, including dimethylsulfide (DMS), and the other dimethylsulfoniopropionate-derived compounds (DMSPCs), namely, DMSP, acrylate, and dimethylsulfoxide (DMSO), in waters around colonies of two scleractinian corals (Acropora pulchra and Pocillopora sp.) and the brown seaweed Turbinaria ornata in Mo’orean reefs, French Polynesia. Concentration gradients indicated that the corals were sources of DMSPCs, but less or null sources of VOCs other than DMS, while the seaweed was a source of DMSPCs, carbonyl sulfide (COS), and poly-halomethanes. A focused study was conducted around an A. pulchra colony where VOC and DMSPC concentrations and free-living microorganism abundances were monitored every 6 h over 30 h. DMSPC concentrations near the polyps paralleled sunlight intensity, with large diurnal increases and nocturnal decrease. rDNA metabarcoding and metagenomics allowed the determination of microbial diversity and the relative abundance of target functional genes. Seawater near coral polyps was enriched in DMS as the only VOC, plus DMSP, acrylate, and DMSO, with a large increase during the day, coinciding with high abundances of symbiodiniacean sequences. Only 10 cm below, near the coral skeleton colonized by a turf alga, DMSPC concentrations were much lower and the microbial community was significantly different. Two meters down current from the coral, DMSPCs decreased further and the microbial community was more similar to that near the polyps than that near the turf alga. Several DMSP cycling genes were enriched in near-polyp with respect to down-current waters, namely, the eukaryotic DMS production and DMS oxidation encoding genes, attributed to the coral and the algal symbiont, and the prokaryotic DMS production gene dddD, harbored by coral-associated Gammaproteobacteria. Our results suggest that solar radiation-induced oxidative stress caused the release of DMSPCs by the coral holobiont, either directly or through symbiont expulsion. Strong chemical and biological gradients occurred in the water between the coral branches, which we attribute to layered hydrodynamics.

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Coral reefs as a source of climate-active aerosols

Cited by 2 publications

References 176 publications

Cloudiness reduces the bleaching response of coral reefs exposed to heat stress

Cloudiness reduces the bleaching response of coral reefs exposed to heat stress

Spatial and diel patterns of volatile organic compounds, DMSP-derived compounds, and planktonic microorganisms around a tropical scleractinian coral colony

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