Restoration effort of Great Bay making 'measurable progress'
PORTSMOUTH — The effort to restore reefs of live oysters to the Great Bay estuary is in it's sixth year and making measurable progress.
|Map of New Hampshire's Great Bay|
With 15.5 acres of reef constructed and more than 13 million adult oysters restored to the estuary already, the effort is the largest of its kind north of Chesapeake Bay.
“We're a little ahead of schedule,” said the Conservancy's director of external affairs, Jim O'Brien.The Nature Conservancy and its partners at the University of New Hampshire have been busy attempting to restore the “once abundant shellfish to a natural system stressed from a number of factors including loss of habitat and increased nitrogen levels.”
This summer's reef restoration, in the bay near Newmarket, was completed Wednesday. O'Brien said the population first collapsed in the 1990s when a waterborne disease made its way up the coast from the southern states.
“It really decimated the population,” he said. “It wiped out the vast majority, (90 percent), of the reefs.”
The oysters now being introduced are special disease-resistant oysters raised at a UNH laboratory by Dr. Ray Grizzle. The group is hoping these oysters will grow a more resilient population.
The shellfish play an integral role in sustaining the estuary and filtering harmful pollutants out of the water. O'Brien said the creatures offer three benefits: providing a physical reef structure, which acts as a physical barrier in the water column to help prevent erosion; serving as a habitat for many species of fish and eel grass; and filtering nitrogen and other pollutants.
“Oysters are water filters,” he said, explaining one oyster can filter as many as 20 gallons of water each day on its own. With Great Bay suffering from increased nitrogen levels, oysters provide a natural solution.
“The more oysters, the more filtering of nitrogen they do and the less nitrogen in the water,” O'Brien said, adding the reefs are built near wastewater treatment plants that are already closed off to harvest.
It is interesting that New Hampshire has found ways to place oysters in closed waters while those in Massachusetts remain inflexible on this point.
Although the group has worked to construct acres of reefs the past several years, O'Brien said the goal is for the oysters and the reefs to eventually become self-sustaining. The reefs are built by laying several hundred tons of dried, recycled surf clam shell to the estuary channel bottom in arranged plots. The shell layer acts as the foundation for the living reefs, which then act as “spawner sanctuaries” for the rest of the estuary.
“The restoration of oysters may be Great Bay's best hope for a sustainable recovery of the estuary” said Dr. Ray Konisky, the conservancy's director of marine science. “These resilient animals are amazing natural water filters — with mature reefs having the ability to naturally remove tons of nitrogen annually from the system. We feel strongly that oyster restoration is a natural solution that will help bring the Bay back into balance.”
The scientists' goal is to restore 100 acres by “ramping up” their efforts in the next few years. Konisky believes the reefs will offer “dramatic, long-term benefits for the natural system” and are simply “a common sense solution that will assist our communities in meeting their nitrogen reduction goals.”
The newest reefs were constructed earlier this week by marine scientists from the Nature Conservancy and UNH alongside local marine contractors Riverside & Pickering and Granite State Minerals. Later this summer, more than a half-million of Grizzle's lab-raised oysters will be placed on the newly constructed reef. The reef will be monitored to measure oyster growth, habitat restoration and overall reef success.
Funding for the project comes from federal, state, and private sources. Lead funders include the Piscataqua Region Estuaries Partnership, National Oceanic and Atmospheric Administration Restoration Center, N.H. Department of Environmental Services and many private donors.