Not as bad as they thought: Coral can recover from climate change damage

Watts Up With That?
Tuesday , January 12th, 2010

From a University of Exeter press release, another inconvenient truth about our planet sure to be denounced by some who claim that global warming is irreparably damaging reef systems.

A study by the University of Exeter provides the first evidence that
coral reefs can recover from the devastating effects of climate change.
Published Monday 11 January in the journal PLOS One, the
research shows for the first time that coral reefs located in marine
reserves can recover from the impacts of global warming.

Scientists and environmentalists have warned that coral reefs may
not be able to recover from the damage caused by climate change and
that these unique environments could soon be lost forever. Now, this
research adds weight to the argument that reducing levels of fishing is
a viable way of protecting the world’s most delicate aquatic
ecosystems.

Increases in ocean surface water temperatures subject coral reefs to
stresses that lead quickly to mass bleaching. The problem is
intensified by ocean acidification, which is also caused by increased CO₂. This decreases the ability of corals to produce calcium carbonate (chalk), which is the material that reefs are made of.

Approximately 2% of the world’s coral reefs are located within
marine reserves, areas of the sea that are protected against
potentially-damaging human activity, like dredging and fishing.

The researchers conducted surveys of ten sites inside and outside
marine reserves of the Bahamas over 2.5 years. These reefs have been
severely damaged by bleaching and then by hurricane Frances in the
summer of 2004. At the beginning of the study, the reefs had an average
of 7% coral cover. By the end of the project, coral cover in marine
protected areas had increased by an average of 19%, while reefs in
non-reserve sites showed no recovery.

Professor Peter Mumby of the University of Exeter said: “Coral
reefs are the largest living structures on Earth and are home to the
highest biodiversity on the planet. As a result of climate change, the
environment that has enabled coral reefs to thrive for hundreds of
thousands of years is changing too quickly for reefs to adapt.

“In order to protect reefs in the long-term we need radical action to reduce CO₂
emissions. However, our research shows that local action to reduce the
effects of fishing can contribute meaningfully to the fate of reefs.
The reserve allowed the number of parrotfishes to increase and because
parrotfish eat seaweeds, the corals could grow freely without being
swamped by weeds. As a result, reefs inside the park were showing
recovery whereas those with more seaweed were not. This sort of
evidence may help persuade governments to reduce the fishing of key
herbivores like parrotfishes and help reefs cope with the inevitable
threats posed by climate change”.

Professor Mumby’s research was funded by National Environment
Research Council (NERC) and the Khaled bin Sultan Living Oceans
Foundation.

Reef facts

• A coral reef is made up of thin layers of calcium carbonate
  (limestone) secreted over thousands of years by billions of tiny soft
  bodied animals called coral polyps.
• Coral reefs are the world’s most diverse marine ecosystems
  and are home to twenty-five percent of known marine species, including
  4,000 species of fish, 700 species of coral and thousands of other
  plants and animals.
• Coral reefs have been on the planet for over 400 million years.
• The largest coral reef is the Great Barrier Reef, which stretches
  along the northeast coast of Australia, from the northern tip of
  Queensland, to just north of Bundaberg. At 2,300km long, it is the
  largest natural feature on Earth.
• Coral reefs occupy less than one quarter of one percent of the
  Earth’s marine environment, yet they are home to more than a
  quarter of all known fish species.
• As well as supporting huge tourist industries, coral reefs protect shorelines from erosion and storm damage.

To download high quality reef videos by Professor Peter Mumby: www.reefvid.org

The main funding for the research came from Khaled bin Sultan Living
Oceans Foundation and the Natural Environment Research Council.

The Khaled bin Sultan Living Oceans Foundation (www.livingoceansfoundation.org)
is dedicated to conservation and restoration of living oceans and
pledges to champion their preservation through research, education and
a commitment to Science Without Borders®.