Rising CO2 levels 'put shellfish in danger'
Pastor Dale Morgan
Rising CO2 levels 'put shellfish in danger'*
By Henry Samuel in Paris
Last Updated: 1:50am GMT 21/03/2007
BBC - Oysters and mussels, two pearls of France's gastronomic heritage,
are in danger of dying out because of rising greenhouse gas levels in
seawater, say scientists.
French and Dutch researchers found that rapidly rising concentrations of
carbon dioxide in seawater is having potentially devastating effects on
the lifecycles of both types of shellfish, slowing down their growth and
weakening their shells, leaving them vulnerable to predators.
This is the first time this effect has been shown on shellfish, the
researchers say.
The study, conducted by France's CNRS research centre with the
Netherlands Institute of Ecology, shows that higher carbonic acid levels
in the ocean increase acidity, which makes it harder for the molluscs to
calcify their shells. All sea life needing calcium carbonate for its
shell, including coral, is at risk.
Oceans absorb a third of the atmosphere's carbon dioxide. Levels have
risen by 30 per cent since the beginning of the industrial revolution,
but could increase by up to four times by the end of the century.
If the amount absorbed only doubles, mussel growth will drop by a
quarter and oysters by 10 per cent by 2100. But at higher carbone
dioxide concentrations, mussel shells may dissolve completely, the
researchers found. Oysters are less affected, as they use another
crystalline form of calcium carbonate for their shells.
France produces 200,000 tons of shellfish annually, amounting to £450
million in revenue. The industry employs around 20,000 people.
The image of French oysters suffered last year when authorities banned
the sale of them in Arcachon, south-west France, after two suspect
deaths. It was later established that there was no link with oyster
consumption.