Dimethylsulfide and Coral Bleaching: Links to Solar Radiation, Low Level Cloud and the Regulation of Seawater Temperatures and Climate in the Great Barrier Reef

Abstract

Coral reefs produce atmospheric dimethylsulfide (DMS a ) which oxidises to non-sea-salt (nss) sulfate aerosols, precursors of cloud condensation nuclei (CCN) and low level cloud (LLC), reducing solar radiation and regulating sea surface temperatures (SSTs). Here we report measurements of solar radiation, SST, LLC, DMS flux,

The Flux and Emission of Dimethylsulfide From the Great Barrier Reef Region and Potential Influence on the Climate of NE Australia

“…Daily SST measurements were made by Australian Institute of Marine Science (AIMS) at GeofB at 18°92′, 147°S from 1993 to 1994, close to NBR (Jones, ; Jones et al, , ). These SST measurements were used to calculate DMS w at GeofBR using a statistically significant correlation between DMS w and SST (Jones et al, ), and equation to determine DMS flux.…”

“…Benthic coral reefs produce appreciable quantities of dimethylsulfide (DMS), a trace sulfur gas that is thought to be involved in climate regulation of sea surface temperatures (SSTs) of coral reefs (Cropp et al, ; Fischer & Jones, ; Jones, ; Jones et al, ; Leahy et al, ). This potential coral reef‐climate feedback is similar to the well‐known global ocean‐climate feedback that involves production of DMS from pelagic phytoplankton, oxidation in the atmosphere to sulfate aerosols, formation of cloud condensation nuclei (CCN), and low level clouds, which in turn lower solar radiation and SSTs, thereby keeping ocean temperatures stable (Charlson et al, ).…”

“…However, the increased frequency of coral bleaching in the GBR in the last two decades (Berkelmans et al, ; Berkelmans & Oliver, ; Berkelmans & van Oppen, ; Hoegh‐Guldberg, ; Oliver, ) and the back to back mass coral bleaching events in 2016 and 2017, where the top third of the GBR bleached (Hughes et al, ), could suggest that the strength of this feedback is decreasing and the GBR has reached a tipping point (Jackson et al, ). While the effect of mass coral bleaching on coral cover in the GBR is controversial (Osborne et al, ), increased aerosol production from coral reefs in summer could cause significant aerosol‐cloud radiative effects that increase SSTs above the coral bleaching threshold of 30 °C (Jones et al, ). Rather than GHGs being the main driver of coral bleaching the increased frequency of these mass coral bleaching events could also be a function of reef produced aerosol‐radiative effects.…”

“…Rather than GHGs being the main driver of coral bleaching the increased frequency of these mass coral bleaching events could also be a function of reef produced aerosol‐radiative effects. It is vital that further research is undertaken on this potential coral‐derived climate feedback as recent research suggests that both cooling and warming in the GBR could occur from the variable emissions of DMS a from the actual coral reefs, with warming (i.e., SSTs >30 °C) a result of increased downwelling of solar radiation and marked decreases in AOD in summer over the GBR (Fischer & Jones, ; Jackson et al, ), enhancing coral bleaching (Jones et al, ; MacKellar et al, ).…”

High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management

“…We found UV radiation to be an important explanatory factor for coral bleaching, consistent with previous studies (Hoegh-Guldberg, 1999; Maina et al, 2008, 2011; McClanahan, Maina & Ateweberhan, 2015). Other variables related to cooling (DCW; Jones et al, 2017) and screening (water turbidity; West & Salm, 2003; Oliver, Berkelmans & Eakin, 2009; Maina et al, 2011; Oxenford & Vallés, 2016) also explained variation in the occurrence of coral bleaching. Small-scale topographic variables, including water depth, are known to reduce thermal stress on corals (West & Salm, 2003; Oliver, Berkelmans & Eakin, 2009).…”