[Coral-List] Production of "Cloud Seeding" chemicals from coral reefs in the Great Barrier Reef decrease during coral bleaching

Graham Jones gjones at scu.edu.au
Tue Nov 6 00:55:12 EST 2007

Production of "Cloud Seeding" chemicals from coral reefs in the Great 
Barrier Reef decrease during coral bleaching

A study of dissolved dimethylsulfide (DMSw), dissolved and 
particulate dimethylsulfoniopropionate (DMSPd, DMSPp), and 
atmospheric dimethylsulfide (DMSa) was carried out at two inshore 
fringing coral reefs (Orpheus Island and Magnetic Island) in the 
Great Barrier Reef (GBR) to investigate the variation of these 
organosulfur substances with season, sea surface temperature, tides 
and time of day. Highest concentrations of these organosulfur 
substances occurred in the summer months at both reefs, with lowest 
concentrations occurring during winter, suggesting a biological 
source of these compounds from the reef flats.

Chamber experiments with the staghorn coral, Acropora formosa 
confirmed that corals produce DMSw in the day, and DMSw and DMSPd 
were significantly correlated with SST. During severe coral bleaching 
at the eutrophic Magnetic Island reef in the summer, DMSw 
concentrations decreased at SSTs greater than 30oC, suggesting that 
reef production of DMSw decreases during elevated SSTs. This was 
confirmed in chamber experiments with Acropora formosa, which showed 
that when this coral was exposed to temperatures at its bleaching 
threshold, decreased production of DMSw occurred. These results 
suggest that DMS and DMSP in coral zooxanthellae may be functioning 
as antioxidants. The amount of solar radiation absorbed by the ocean 
is reputed to be effected by levels of atmospheric dimethylsufide and 
its oxidation products. Interesting questions have now been raised on 
the role of these substances in corals, whether DMS emissions from 
coral reefs could have an effect on regional climate in the Great 
Barrier Reef and whether these substances have an effect on the 
severity of coral bleaching in the GBR. See:

"Factors affecting the cycling of dimethylsufide and 
dimethylsufoniopropionate on coral reef waters of the Great Barrier Reef"

Graham Jones, Mark Curran, Andrew Broadbent, Stacey King, Esther 
Fischer, Rosemary Jones (2007). Environmental Chemistry 4, 310-322. 

Associate Professor Graham Jones
School of Environmental Science & Management
Southern Cross University
Lismore Campus
PO Box 157
NSW 2480

Director of the Centre for Climate Change Studies

Honours Coordinator

Telephone: (02) 66203009
Fax: (02) 66212669
Email: gjones at scu.edu.au

web page:http://www.scu.edu.au/schools/esm/index.php?page_id=69&menu=14_97

More information about the Coral-List mailing list