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ARCHIVED - Army of 60 million oysters to decontaminate the Mar Menor

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A promising project reveals that the mollusc could filter nitrates from the Murcia lagoon

<span style='color:#780948'>ARCHIVED</span> - Army of 60 million oysters to decontaminate the Mar Menor

Researchers working with the Spanish Institute of Oceanography (IEO-CSIS) have come up with a novel proposal for halting the deterioration of the Mar Menor: oysters. Specifically the flat oyster, a mollusc that, in great enough number, could potentially reverse the damage caused to the lagoon by filtering the nitrates that develop there, thanks to the excessive run-off from nearby farming land.

Thirty years ago, the Mar Menor boasted a population of 135 million flat oysters, but today it is estimated that only a couple of thousand survive, and this number could be as low as a few hundred, according to Marina Albentosa, head scientist of the IEO-CSIC at its headquarters in Lo Pagán in San Pedro del Pinatar.

“Along with the shellfish, the flat oyster entered the Mar Menor in the seventies, when the Estacio channel was opened,” Ms Albentosa explained, and while it’s not clear how their numbers diminished so much in the intervening years, it is likely that the chemical conditions of the lagoon changed, resulting in their asphyxiation, as happened all too recently with other small fish and crustaceans.

To remedy this, scientists at the IEO-CSIC laboratories in Lo Pagán have already begun breeding the oysters, and they will remain in captivity until grown, and are ready to be transferred to the Mar Menor.

According to very preliminary calculations, sixty million oysters would be needed for their filtering function to have a positive effect on the polluted waters, so this is no immediate solution and would have only a complimentary role to play “within a comprehensive action plan that must include the elimination of land discharges.”

The project has enormous ecological implications as it would involve recovering a species as well as a habitat: nature coming to the aid of nature.

The good news for the oysters is that, given the poor quality of the water of the Mar Menor, they would not be edible, and nor would they be harvested for pearls, since this particular species doesn’t produce them.

Their role in the environment, however, would be the real gem: removal of excess nutrients from the water, storage of CO2 in their valves and obtaining calcium carbonate from their shells.

Further reading: Why it is so difficult to solve the current problems in the Mar Menor

Image: IEO-CSIC