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

Abstract

Concentrations of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS), and DMS flux are reported for the Great Barrier Reef (GBR), Great Barrier Reef Lagoon (GBRL), and Coral Sea. Generally higher concentrations of dimethylsulfoniopropionate and DMS occurred in coral reef waters, compared with GBRL concentrations. DMS flux from GBR coral reefs in summer ranged from nondetectable to 153 μmol m−2 d−1 (mean 6.4), while winter fluxes ranged from 0.02 to 15 μmol m−2 d−1 (mean 2.4). No significant seasonal difference in DMS flux occurred for the GBRL. High DMSw concentrations and DMS fluxes periodically occur at coral reefs during very low tides and elevated sea surface temperatures (SSTs). For the GBRL and GBR coral reefs there was a significant correlation between seawater DMSw concentrations and SST (p < 0.001), up to temperatures of 30 °C. During coral bleaching DMS flux from reefs almost completely shuts down when SSTs are >30 °C. The GBRL and associated coral reefs emit 439 and 32 MmolS per year, respectively. Cyclones on average produce 170 MmolS to the GBR atmosphere in summer. This amount can markedly increase during severe cyclones such as severe tropical Cyclone Debbie in March 2017. Overall, the annual DMS emission estimate from the GBRL and coral reefs in the GBR is 0.64 GmolS, with cyclones contributing 27% or greater of the annual emission estimate, depending on the cyclone intensity. Oxidation of atmospheric DMS can potentially affect solar radiation, SSTs, low‐level cloud cover, and rainfall causing cooling and warming of the climate in the GBR region as recent modeling predicts.

Coral Reef Emissions of Atmospheric Dimethylsulfide and the Influence on Marine Aerosols in the Southern Great Barrier Reef, Australia

“…The results presented in this analysis support existing findings that corals in the GBR are a significant source of DMS a (Fischer & Jones, 2012; Haydon et al, 2018; Jones et al, 2018; Raina et al, 2013; Swan et al, 2016; Swan, Jones, Deschaseaux, & Eyre, 2017). Ongoing ocean warming and coral bleaching may therefore lead to a change in DMS emissions from the GBR.…”

“…The coral reef flat often becomes aerially exposed during low tide and DMS may be directly transferred from the coral reef to the MBL (Hopkins et al, 2016; Swan, Jones, Deschaseaux, & Eyre, 2017). DMS emissions also increase on rising tides when DMS in coral mucous dissolves and accumulates in tidal slack waters (Hopkins et al, 2016; Jones et al, 2007; Jones et al, 2018; Swan, Jones, Deschaseaux, & Eyre, 2017). The highest spike occurred during the evening low tide of 25 July and Swan, Jones, Deschaseaux, and Eyre (2017) concluded that rainfall (hyposalinity) and rapid temperature change stressed the exposed corals.…”

Reviews and syntheses: Marine biogenic aerosols and the ecophysiology of coral reefs

“…As Acropora are the dominant genus throughout the Indo-Pacific and are amongst the strongest producers of DMS/P, it was estimated that corals in the GBR release 3 -11 mmol S m -2 day -1 . According to this estimate the GBR releases 0.01 -0.04 Tg S yr -1 , consistent with the estimate provided by Jones et al (2018). Assuming that DMS flux is constant across coral reefs and lagoon waters, tropical coral reefs (~600,000 km 2 ) emit 0.02 -0.08 Tg S yr -1 .…”

“…km 2 ) are estimated to emit 0.02 Tg S year -1 (Jones et al, 2018). It is noted that coral cover in the GBR is ~20,000 km 2 and consequently, DMS flux from the surrounding lagoon was far higher than estimates from the coral reef.…”

Dimethylsulfide (DMS), marine biogenic aerosols and the ecophysiology of coral reefs

“…However, high LLC cover significantly reduced the amount of surface solar radiation at coral reefs in the nearby So-ciety Islands, where bleaching did not occur (Mumby et al, 2001b). Similarly, high SST (> 31 • C) in 1994 caused coral bleaching at Nelly Bay (Magnetic Island) in the central GBR (Jones et al, 1997); however, no bleaching was observed ∼ 60 km away at Pioneer Bay (Orpheus Island; Jones et al, 2007). Jones et al (2017) examined DMS a before, during and after this bleaching event at both locations.…”