Reef boom beats
doom
Thursday, April 23,
2009
Corals Bleaching
Coral Beds Dominated By Algae
Corals Restored In 2008
Marine scientists say they are
astonished at the spectacular recovery of certain coral reefs in
Australia's Great Barrier Reef Marine Park from a devastating coral
bleaching event in 2006.
That year high sea temperatures caused massive and severe coral
bleaching in the Keppel Islands, in the southern part of the GBR.
The damaged reefs were quickly smothered by a single species of
seaweed – an event that can spell the total loss of the
corals.
However, a lucky combination of rare circumstances meant the reefs
were able to achieve a spectacular recovery, with abundant corals
re-established in a single year, says Dr Guillermo Diaz-Pulido,
from the ARC Centre of Excellence for Coral Reef Studies (CoECRS)
and the Centre for Marine Studies at The University of
Queensland.
Dr Diaz-Pulido explains that the rapid recovery is due to an
exceptional combination of previously-underestimated ecological
mechanisms.
"Three factors were critical. The first was exceptionally high
re-growth of fragments of surviving coral tissue. The second was an
unusual seasonal dieback in the seaweeds, and the third was the
presence of a highly competitive coral species, which was able to
outgrow the seaweed.
"But this also all happened in the context of a well-protected
marine area and moderately good water quality", said Dr
Diaz-Pulido.
"It is rare to see reports of reefs that bounce back from mass
coral bleaching or other human impacts in less than a decade or
two," he adds
"The exceptional aspect was that corals recovered by rapidly
regrowing from surviving tissue. Recovery of corals is usually
thought to depend on sexual reproduction and the settlement and
growth of new corals arriving from other reefs. This study
demonstrates that for fast-growing coral species asexual
reproduction is a vital component of reef resilience" says Dr
Sophie Dove, also from CoECRS and The University of
Queensland.
"Coral reefs globally are increasingly being damaged by mass
bleaching and climate change, and their capacity to recovery from
that damage is critical to their future," explains Prof. Ove
Hoegh-Guldberg of CoECRS and The University of Queensland. "Our
study suggests that managing local stresses that affect reefs such
as overfishing and declining water quality can have a big influence
on the trajectory of reefs under rapid global change."
"Clearly, we need to urgently deal with the problem of rising
carbon dioxide in the atmosphere, but managing reefs to reduce the
impact of local factors can buy important time while we do this,"
he says.
Understanding the different mechanisms of resilience is critical
for reef management under climate change. "Diversity in processes
may well be critical to the overall resilience and persistence of
coral reef ecosystems globally," Dr Laurence McCook, from the Great
Barrier Reef Marine Park Authority, says.
The research was partially funded by a Pew Fellowship in Marine
Conservation awarded to Dr McCook, the Great Barrier Reef Marine
Park Authority as well as the ARC Centre of Excellence
program.
"This combination of circumstances provided a lucky escape for the
coral reefs in Keppel Islands, but is also a clear warning for the
Great Barrier Reef. As climate change and other human impacts
intensify, we need to do everything we possibly can to protect the
resilience of coral reefs," he adds.
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ARC Centre of Excellence in Coral Reef Studies
Thanks to ARC Centre of Excellence
in Coral Reef Studies for this article.