The influence of coral reefs on atmospheric dimethylsulphide over the Great Barrier Reef, Coral Sea, Gulf of Papua and Solomon and Bismarck Seas

Abstract

Marked regional differences in dissolved dimethylsulphide (DMS), atmospheric DMS and DMS flux were recorded during July 1997 through the northern Great Barrier Reef, Coral Sea, Gulf of Papua, Solomon and Bismarck Seas. Highest concentrations of dissolved DMS occurred in the Coral Sea, Gulf of Papua and Bismarck Sea, with lower concentrations in the Great Barrier Reef and Solomon Sea. Elevated levels of atmospheric DMS often occurred in south-easterly to southerly trade winds sampled in the region 18°32′–8°12′S to 145°–151°E, where the highest biomass of coral reefs occurred. Atmospheric DMS often increased in the day after low tides and was positively correlated with tidal height in the northern Great Barrier Reef (r = 0.91, P < 0.05). For tides less than 1.6 m, atmospheric DMS increased on the rising tide for the northern GBR and NW Coral Sea (r = 0.66; P < 0.05) and for the whole voyage (r = 0.25; P < 0.05). As coral reefs have been identified as significant sources of DMS, it is suggested that the daytime increase in atmospheric DMS over much of the study area was mainly a result of high winds and extremely low tides in July, which exposed the reefs during the day.

Coral reef origins of atmospheric dimethylsulfide at Heron Island, southern Great Barrier Reef, Australia

“…1b). This observation supports a previous report of elevated DMS a in SE trade winds that travelled over dense coral biomass areas of the GBR and western Pacific Ocean (Jones and Trevena, 2005). Additionally, at a Queensland coastal site (24.21 • S, 151.90 • E) elevated new particle number concentrations, reflecting a strong nucleation event, were detected in an air stream that travelled over the Capricorn-Bunker Group of southern GBR reefs on 30 March 2007 (Modini et al, 2009).…”

“…This will lower the diffusivity resistance for mass transfer of DMS through the seawater surface film, as described by the Schmidt number, which is temperature dependent (Saltzman et al, 1993). This thermal effect, which can enhance the air-sea exchange of DMS (Yang et al, 2011), is expected to be pronounced during daytime low tides over coral reefs when elevated atmospheric DMS (DMS a ) concentrations have been observed (Jones and Trevena, 2005). Additionally, DMS may be directly exchanged to the atmosphere from the coral surface if aerially exposed at low tide (Hopkins et al, 2016).…”

“…There are currently insufficient data available from previous GBR DMS a field studies to environmentally assess that recent chamber observation. The few previous field studies that have measured DMS a over the GBR (Broadbent and Jones, 2006;Jones and Trevena, 2005) employed gold-wool chemi-adsorption (Barnard et al, 1982;Kittler et al, 1992), a low-frequency grab-sampling technique. While the investigators of those previous field studies reported that the GBR appears to be a significant source of DMS a , their low-frequency sampling technique did not provide sufficient data to characterise coral reef DMS emissions.…”

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

“…Mean aerosol particle concentrations averaged 3200 cm −3 and consisted of broad pulses of aerosol particles emitted in the morning and afternoon, with a small discrete aerosol burst at mid-day [26], a distribution similar to that measured for DMS a over coral reefs in the central GBR [28]. Periodic pulses of DMS a often occur over coral reefs during very low tides and rising tides [10] [28] [29] [30]. It is apparent that natural stress events (e.g.…”

The opportunistic coral pathogen Aspergillus sydowii contains dddP and makes dimethyl sulfide from dimethylsulfoniopropionate

“…Some of these pathways liberate dimethyl sulfide (DMS), an environmentally influential gas in its own right, as DMS oxidation products are cloud condensation nuclei, causing cloud cover over the oceans (Sievert et al, 2007). As corals are hot spots for DMSP production, the levels of DMS downwind of the Great Barrier Reef are enhanced (Jones and Trevena, 2005) with possible effects on the abundance of nucleation particles (Modini et al, 2009).…”