[Coral-List] GBR FCoral Bleaching Conditions Update - 11 February 2004

Paul Marshall paulma at gbrmpa.gov.au
Tue Feb 10 20:54:15 EST 2004

The Great Barrier Reef Marine Park Authority Climate Change Program is
dedicated to observing, understanding and reporting coral bleaching
events and other climate change impacts on the Great Barrier Reef. The
Climate Change Program provides regular reports on conditions on the
Reef throughout summer and publishes early warnings of increases in
levels of stress or widespread bleaching of corals. This is the fifth
Current Conditions Report for the summer of 2003/04.

Updated 11 February 2004

On the basis of current conditions and climate predictions for the
summer of 2004, the threat of widespread coral bleaching for the Great
Barrier Reef (GBR) region is currently rated as HIGH. Sea temperatures
have reached thresholds known to cause bleaching at several locations,
and reports of minor or patchy bleaching have now been received from
numerous locations. However, bleaching has not intensified noticeably at
key monitoring sites, and weather forecasts for the coming week suggest
that some respite in conditions is likely in the short term, at least.

*Weather update*
After an initial increase in sea temperatures since the last report (29
January), temperatures have once again stabilised or decreased over the
last week. Cooler air temperatures, increased winds and spring tides are
all likely to have contributed to the localised cooling of Great Barrier
Reef waters. However, sufficient heat stress has accumulated over the
last few weeks to levels that are known to cause bleaching in sensitive
species at numerous monitoring sites. Temperatures have remained high in
the Coral Sea, suggesting that heat is continuing to accumulate in the
system at a regional level.

Satellite monitoring of sea temperatures by the U.S. National Oceanic
and Atmospheric Administration (NOAA) indicates an encouraging decrease
in sea surface temperatures along most of the Great Barrier Reef,
although unusually warm conditions continue to persist in the Coral Sea.
Recent and forecast conditions on the GBR region over recent weeks give
some cause for renewed optimism that the warming trend seen throughout
most of summer could be weakening. Conditions have moderated over recent
days, and the low pressure system developing northeast of the GBR is
predicted to bring strong winds and the possibility of monsoonal
conditions (heavy cloud cover, rain and strong winds). However, the
unusually warm sea temperatures throughout January have lead to an
accumulation of heat stress that approaches critical thresholds known to
trigger bleaching in susceptible corals and associated reef organisms.
Further warming could easily increase temperature stress to levels that
could trigger widespread and severe coral bleaching.

*Bleaching reports*
Reports of minor or patchy bleaching have been received from BleachWatch
participants at numerous locations, including reefs off Port Douglas,
Cairns, Townsville, Airlie Beach, Orpheus Island and Heron Island. While
the number of reports has increased over recent weeks, the severity of
bleaching has not noticeably escalated. These reports do not necessarily
indicate the onset of a mass bleaching event. However, more serious and
widespread bleaching is likely unless temperatures moderate considerably
over coming weeks.

The Great Barrier Reef Marine Park Authority will continue to closely
monitor the situation with the support of BleachWatch participants and
in conjunction with AIMS and NOAA.

For the full current conditions report, for information on how to join
BleachWatch, and for background information on climate change, coral
bleaching and the Great Barrier Reef, visit the GBRMPA web site:


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

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

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