The Chesapeake Bay was once carpeted with oysters, but that was before centuries of overfishing, pollution, and disease took their toll: Today the oyster population has been reduced to less than 1 percent of its historical population. But a new restoration effort has shown unprecedented progress in bringing the bivalves back. In the Great Wicomico River, a tributary of the Bay, researchers have created a 87-acre oyster colony that contains about 185 million oysters.
The Chesapeake’s oyster reefs were destroyed by centuries of watermen towing rakelike metal “dredges” and silted over by dirt flowing from the mid-Atlantic’s farms and growing cities. The final blow came in the mid-20th century: A pair of new diseases killed oysters by the millions. Now, in many places, the bay bottom is a flat expanse of green mud. “Just picture, you know, a clear-cut forest,” said Kennedy Paynter, a biology professor [Washington Post].
In a new study, published in Science, researchers describe the new strategy they used in the Virginia river. They closed the area to harvesting, then in 2004 piled old oyster shells one to two feet high — higher than previous researchers had, they said. They waited for baby oysters to latch on. The idea was to give the oysters a perch out of the dirt-choked water on the bottom [Washington Post]. Five years later, the elevated reefs have five times as many oysters as lower reefs that the researchers also constructed, which tend to sink and get covered in silt.
If the success of the Great Wicomico River could be repeated elsewhere in Chesapeake Bay, it would benefit both the environment and oyster-hungry Americans. Oysters, or bivalve mollusks, play an important role as ecological managers by filtering water. When the animals were more abundant a century ago, they could purify all the water in Chesapeake Bay … in three days compared to a year now [Bloomberg], according to the National Oceanic and Atmospheric Administration. Oyster reefs also provide habitat for small fish and other sea creatures.
However, some experts say that reef building is too expensive to work on a large scale, and others note that the new populations have yet to prove they can survive now-endemic diseases. “It’s very early in the game to call this a success,” says Paula Jasinski [Science], of NOAA.
Related Content:
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DISCOVER: The Most Important Fish in the Sea looks at another dwindling Chesapeake species
Image: Dave Schulte, Russ Burke, and Rom Lipcius
August 3rd, 2009 at 11:19 pm
One has to think that this is a step forward, in spite of Jasinki’s reservations.
We have to give filter feeders a chance. Large scale farming causes over fertilization of the waterways draining those areas. Then massive algal blooms take place and overwhelm the filter feeders in the area. The death of those huge algal blooms then creates the dead zones which wipe out all the higher life forms that depend on oxygen.
If we cannot control the land based farmers (which has been a losing cause to date), then the answer must lie in the filter feeders in the drainage basins. Reestablish them in quantity and maybe we can make the river estuaries healthy again.
Besides, most people like a good oyster, or shrimp, or clam bake. In this case a healthy environment leads to good eating!
August 4th, 2009 at 9:38 am
We need to consider oyster restoration as a worthy and necessary environmental cause seperately from its commercial value. Too often we confuse the discussion and allow oyster policy to be determined by short term return to the commercial oystering industry. It is time for the public to put its weight behind the much larger issues.
August 4th, 2009 at 9:44 am
PS. Just for clarity; someone pointed out confusion caused by the title of this article. The “homes” refers to the oyster’s manmade habitat – the two foot high reefs – not human homes. There is no connection between oyster recovery and elevated human homes on the bay.