Like the rest of us, coral reefs have good
reason to be stressed regarding climate change. Warmer water temperatures,
higher water acidity and stronger storms take their toll on corals and the
marine life that depend on them.
Just how stressed are reefs in the western Indian Ocean? WCS marine scientists have made it their job to find out. They
have developed a test that measures how well, or poorly, the reefs are handling
their changing water conditions. This enables researchers to map out which reefs
have the best shot at survival over the next 50 years or so, and therefore where
to best direct conservation efforts.
future is going to be more stressful for marine ecosystems, and coral and their
dependent species top the list of animals that are going to feel the heat of
climate warming," said WCS’s Tim McClanahan, the study’s lead author. "The
study provides us with hope and a map to identify conservation and management
priorities where it is possible to buy some time for these important ecosystems
until the carbon emissions problems have been solved."
model integrates historical data, satellite imagery, and field observations as
a way of assessing the health of coral communities, their diversity, and their vulnerability
to bleaching. Such evaluations
are important at a time when climate change is beginning to affect ecosystems
worldwide and resources to address them are limited.
western Indian Ocean exhibits a significant portion of the Earth’s overall
biodiversity within tropical reef systems. Unfortunately, the swath of sea between the Maldives and South Africa
has already been the scene of coral death and severe coral bleaching
incidents—when higher water temperatures cause corals to expel the colorful
algae living within their tissues. For instance, during a very warm spell in 1998, an estimated 45 percent
of living coral died. When
corals perish, the reef’s communities of plants, anemone, crabs, fish, turtles
and other marine species often follow or migrate elsewhere.
Now, it’s time for the good news—relatively.
Which reefs showed the highest
biological diversity and the lowest environmental stress? The results shine
most optimistically on the coastal regions stretching from southern Kenya to
northern Mozambique and to northeastern Madagascar. Reefs off the Mascarene
Islands and the coastal border of Mozambique and South Africa also hold promise
for holding strong against climate change.
"Reducing human impacts to minimize the
multiple stressors on these globally important reefs will give corals a
fighting chance in the age of global climate change," said Caleb McClennen,
director of WCS-Marine. "These results reveal a window of opportunity for the
future conservation of the ocean’s most biodiverse ecosystem."