[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.
doi:10.1071/EN06065
Associate Professor Graham Jones
School of Environmental Science & Management
Southern Cross University
Lismore Campus
PO Box 157
Lismore
NSW 2480
Director of the Centre for Climate Change Studies
www.scu.edu.au/schools/esm/index.php?page_id=52&menu=13_74
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
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