World shrinks for oysters

By Nidhi Jamwal
Published: Wednesday 15 July 2009

Down to Earth
Source Shellfish reefs at risk
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85 per cent of shellfish reefs lost in over a century

while billions of us dollars are being spent the world over on treating wastewater, natural filter feeders are dying a silent, unnoticed death in oceans. Oyster reefs, as these natural filters are called, were once a dominant feature in many estuaries. As per the first global assessment of oyster reefs, 85 per cent have been lost over the past 130 years, making oyster reefs the most severely impacted marine habitat on the planet.

As part of an assessment, a US-based conservation group, The Nature Conservancy, studied oyster reefs in 144 bays in 40 eco-regions. The results show that oyster reefs are in poor condition, with more than 90 per cent deterioration in seven out of 10 bays studied. Worse, these reefs are functionally extinct (more than 99 per cent loss) in 37 per cent of the bays (see map).

The assessment report, Shellfish reefs at risk, blames destructive fishing practices and coastal degradation through land reclamation, dredging and building dams, for making oyster reefs functionally extinct. "Reefs, particularly in North America, Australia and Europe, are no longer able to provide any ecosystem services," said the authors when releasing the report on May 21. The report was prepared by scientists from across five continents, from conservation organizations to academic and research institutions.

In China, Japan and Korea, the report blames overfishing and aquaculture for reef decline. Oyster reefs in South America are in a relatively better condition, but declining. Reef restoration is emerging as a community-based strategy there, and is often coupled with acquaculture development.

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