#Status of Coral Reefs 2002 - International Coral Reef Action Network

Status of Coral Reefs of the World: 2002
Coral bleaching and mortality rank as probably the major threat to the reefs in the Pacific
as there are no major problems from runoff from large land masses. Over-exploitation and
destructive fishing on reefs are the other major problems. There was severe bleaching
again in Fiji in the summer of 2002; and the details are being assembled. Coral bleaching
was also observed in parts of Vanuatu in 2002, but there are no monitoring data to
estimate the extent.
MAJOR CORAL BLEACHING ON THE GREAT BARRIER REEF IN 2002
North Queensland had unusually hot and still weather during the summer of 2001-02,
which resulted in increased sea temperatures and stress to the Great Barrier Reef
(GBR). A mass bleaching event followed in the Great Barrier Reef Marine Park, similar
in scale to the 1998 event, but this one affected a much larger area than in 1998, and
the inshore reefs were once again the most severely affected. When the first warning
signals came in December 2001, the Great Barrier Reef Marine Park Authority
(GBRMPA) implemented the ‘Bleaching Response Strategy’ in collaboration with the
Australian Institute of Marine Science (AIMS), the CRC Reef Research Centre (CRC
Reef) and the U.S. National Oceanic and Atmospheric Administration (NOAA). This
Strategy had 4 components: monitoring of sea temperature and levels of stress on the
reef; early warning of coral bleaching via a public reporting program; broad-scale aerial
surveys of the extent and intensity of bleaching on the GBR; and detailed underwater
surveys of the impacts of the bleaching. An important component was to provide
regular reports of reef conditions and survey results to the community via Internet
updates and press releases.
The first aerial surveys showed that the coral bleaching affected almost 60% of the
total GBR reef area. The inshore reefs were more severely affected by bleaching
(similar to 1998), however, many more offshore reefs were affected in 2002, than in
1998. The aerial surveys were followed by more detailed, underwater surveys that
confirmed that few reefs had escaped the effects of the bleaching. There was extensive
mortality on a few inshore reefs, with up to 90% of corals dead at the worst affected
sites, however, it now appears that the majority of reefs will survive the bleaching
event with only minimal coral mortality. A number of reefs in the Coral Sea adjacent
to the GBR (e.g. Flinders and Holmes Reef) also suffered extensive bleaching mortality
with up to 95% of corals dead at some sites. The overall pattern was complex and
highly variable (from negligible to severe), even between reefs at similar distance from
the shore. Bleaching was generally most severe in shallow water and strong patterns of
species susceptibility were seen at all sites. The GBR was fortunate to escape with only
a few reefs suffering extensive coral mortality in the 1998 and 2002 bleaching events.
However, the extent of bleaching on the GBR in 2002 indicates that few reefs are
immune from increased sea surface temperatures. The area affected by bleaching in
2002, combined with the potential for mass coral death at the worst affected sites,
provides a vivid warning of the potential for widespread and severe ecological damage
should warm water events increase in severity, duration or frequency in the future.
From Paul Marshall, David Wachenfeld and Ray Berkelmans.
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