Report: 85 Percent of World's Oyster Reefs Have Been Lost

By Zulima Palacio
Oyster, Virginia
24 July 2009

A recent study by environmental organizations found that nearly 85 percent of the oyster reefs worldwide have been lost. But beyond providing food around the world, oyster reefs play a key role in the oceans.

Oyster population near extinction

For centuries, people around the world have looked forward to reuniting their taste buds when these delicious oysters came into season. Once abundant and cheap, fishermen harvested them as if they had an endless supply. But, as popularity grew, oyster reefs around the world became over harvested.
 
A recent study now says that shellfish reefs are one of the most imperiled marine habitats on Earth, with an estimated 85 percent loss globally.
 
The study published by the environmental organization The Nature Conservancy and a number of other research organizations highlight the importance of oysters to marine life.

Recommendations for repopulating oysters

They recommended a variety of steps, such as listing oysters as endangered species, treating their habitat as protected areas like wetlands, using shells to rebuild reefs and supporting aquaculture to raise oysters instead of fishing wild populations.

"Oysters are important because they provide the ecosystem services to coastal bays and estuaries," said Barry Truitt, chief conservation scientist with The Nature Conservancy in the Virginia Coast Reserve. "They filter water, they remove sediments out of the water, they are ecosystems engineers in that they create habitat for other organisms like muscles and fish."

On the U.S. Atlantic Coast, the Chesapeake Bay was once the epicenter for the shellfish industry in the United States. But overfishing, water pollution and illness killed more than 90 percent of them in the last two decades.

Out of the small coastal town of Oyster, Barry Truitt and Bo Lusk are leaders in the restoration of sea grasses and oyster reefs on this coast.

"This white edge, here and here, shows you that these oysters are fast growing this time of the year," Truitt said.

This is a restored oyster reef, where oysters like to grow attached to other oysters.  It is low tide now but in a few hours this reef will be completely under water again.

"These are smaller oysters that are starting to grow on the bigger ones that are underneath," Truitt points out.

But one of the biggest challenges to re-building reefs is finding enough shells.

"People harvested oysters for hundreds of years and they used the shells to build roads and provide calcium to chicken farms instead of planting the shells back over board where they could be use to create more oysters," he adds.

An experimental initiative began a year ago to use marine friendly concrete blocks for oysters to attach and grow. This nearby site is called Oyster Castles.

Protecting marine life

The Nature Conservancy is now protecting over 160 square kilometers in this coastal region to restore the base of the marine food chain consisting of salt marsh grasses, oysters and sea grass.

"We have been able to get oysters to grow where they haven't been growing," said Bo Lusk,  marine steward with The Nature Conservancy. "We have been able to get oysters to grow past the state where they were typically dying or being harvested."

"The industry as a wild harvest is never probably going to come back to any degree, the future is going to be with aquaculture," Truitt explains.

Professor Mark Luckenback from the Virginia Institute of Marine Science has been working with oysters for more than 20 years. He says aquaculture is now responsible for most of the production of oysters around the world.

"The issue is that oysters face a multitude of stresses in coastal environments; from water quality to algae blooms, to high sediment loads and some of the places are too far gone," he said.

Oysters are ecosystem engineers that filter water and remove pollution and excess nutrients that can spark algae blooms. But, Luckenback says, their capacity has a limit and research shows that oysters expose to a variety of toxins have been shown to be more susceptible to diseases and death. 

"We have the ability in aquaculture, to select for the sizes, the shapes, the growth forms that you like," he said. "These two oysters are the same species."

Scientists say that aquaculture will eventually support the entire shellfish industry for human consumption. But oyster reefs are more than just a meal. They play a key role in the marine life by protecting coastlines from storms and erosion.

"You can think of an oyster reef as the temper equivalent of a coral reef like we have down the tropics. They provide habitat and feeding area for a whole host of other animals," said professor Arthur Schwarzschild who directs the Coastal Research Center with the University of Virginia.

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