A rise in the temperature and acidity of
the oceans that threatens the existence of the world's coral reef
ecosystems could also have troubling implications for marine life and
fishing industries as far away as Maine, a University of Maine
Robert Steneck, a professor of marine sciences, is
one of several authors of a new study predicting that increasing
concentrations of carbon dioxide in the atmosphere, if not abated,
will continue to deteriorate coral reefs to the point where they are
likely to disappear altogether in the next few decades.
The potential collapse of these most biologically
diverse and economically important ecosystems suggests a global
atmospheric crisis that, Steneck says, could seriously harm fisheries
"The Carbon Crisis: Coral Reefs Under Rapid Climate
Change and Ocean Acidification," which represents the work of scientists
from around the world, was published in December in the journal Science.
"While we are far from where coral reefs live, I
think it's important to consider what this might mean in Maine," says
Steneck, who is based at UMaine's Darling Marine Center in Walpole.
"It's not as if coral reefs are on a different planet with a different
atmosphere. They may be the canary in the mine shaft Earth, and the
canary ain't doing so swell these days."
Scientists estimate that 25 percent of the world's
coral reefs are already gone or severely damaged and that another third
are degraded and threatened. Rapid increases in carbon dioxide
emissions, which in the 20th century have raised the average temperature
of the world's oceans by more than 1 degree Fahrenheit, "may be the
final insult to these ecosystems," the study states.
The acidity caused when carbon dioxide and water
combine to make carbonic acid reduces the availability of calcium
carbonate, or limestone, in the sea. Coral reefs are made of limestone,
and lobsters, sea urchins, clams and scallops need it to calcify the
hard parts of their bodies. Pteropods, a small, swimming organism with
shells inside their bodies, are a major food source for Atlantic salmon.
Yet, Steneck says, there is evidence that their shells, which the
organisms can't live without, are already eroding.
A healthy Caribbean coral reef near Bonaire
A degraded Caribbean coral reef in the Bahamas
Photos by Robert Steneck
Reduced carbonates in the world's oceans are forcing
marine creatures to spend more energy making their shells, which places
them under greater stress. According to Steneck, about 30 new
stress-induced coral diseases have been identified in the last decade.
"And in Maine, anything that stresses
shell-producers makes them more susceptible to disease," he says. "In
Rhode Island in 1998,there was a large-scale die-off of lobsters. If the
same thing happened in Maine, where lobsters represent 85 percent of all
marine resource value, it would threaten the socioeconomic fabric along
the entire coast."
While some marine organisms have shown they can
adapt to warmer temperatures, Steneck says, the projected increases in
carbon dioxide buildup and temperature will overwhelm that ability in
the decades to come.
Steneck, who does fieldwork in Central America and
Mexico, is part of an international science program called Coral Reef
Targeted Research. Funded by the Global Environmental Facility and the
World Bank, the partnership of 40 research institutes seeks to reduce
global poverty in developing countries that depend on coral reefs for
fishing, tourism and coastal protection.
"We do have a global atmospheric crisis and we have
to work on a global level to change it," Steneck says. "The point is not
to be alarmist, but rather to say that we have to redouble our efforts
to curb emissions. We need to generate more political will to do it."
Because eliminating emissions won't happen
overnight, Steneck urges the fishing industries in Maine and elsewhere
to manage themselves with greater sensitivity to the health of the
ecosystems that sustain them.
"The trajectory of a planet that is getting rapidly
warmer and more acidic will likely affect organisms globally," he
cautions. "The problem is in our backyard."
by Tom Weber
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