[Coral-List] Great Barrier Reef - Coral Bleaching Update

[Paul Marshall]

Updated 1 April 2004

On the basis of current conditions and recent observations, the threat 
of a major coral bleaching event for the Great Barrier Reef (GBR) region 
has now passed for this summer.

Sea temperatures have decreased substantially throughout the GBR region 
since the last report (10 March). Stress levels reached their maximum 
around 2 March, as indicated by HotSpot maps of sea surface temperature. 
Fortunately, temperatures have cooled consistently since this time, 
leading to a return to normal conditions throughout the GBR. As the 
cooler conditions of autumn have now set in, the risk of any further 
bleaching has abated.

Reports indicate that sites throughout the GBR that had experienced 
minor stress this summer are now showing noticeable improvement. Signs 
of minor bleaching (upper surfaces and ends of branches white, or enitre 
colonies pale) have been recorded from sites spanning over 1000 km, with 
the most extensive bleaching seen in far northern offshore reefs and 
southern inshore areas. More severe bleaching has been reported from 
reefs in the Coral Sea, beyond the outer boundary of the Great Barrier 
Reef Marine Park.

In combination, these observations indicate that only minor coral 
bleaching has occurred on the GBR this summer, with minimal or no coral 
death. Thus, while the unusually warm conditions that occurred over 
recent months have caused visible stress in many parts of the GBR, the 
level of bleaching is much less than was seen at this time during the 
major bleaching events in 1998 and 2002.

For the full current conditions report, for information on the GBR Coral 
Bleaching Response Plan and for background information on climate 
change, coral bleaching and the Great Barrier Reef, visit the GBRMPA web 
site: www.gbrmpa.gov.au.

-- 
Dr Paul Marshall
Manager
Climate Change Program
Research & Monitoring Co-ordination Unit
Great Barrier Reef Marine Park Authority
PO Box 1379
Townsville QLD 4810
Australia

email: p.marshall at gbrmpa.gov.au
phone: 07 4750 0771
fax:   07 4772 6093
mobile:0428 889 812