Man-made oyster reef is ‘flourishing,’ bay foundation says

A year after baby oysters were deposited on a new man-made reef near the Francis Scott Key Bridge, the bivalves are flourishing despite a legacy of Patapsco River pollution.

Photos of the project shared by the Chesapeake Bay Foundation show mounds of oysters, some at least 3 inches long. The reef has also created habitat for crabs, anemone and other creatures.

“Oysters are resilient creatures. If we give them the habitat they need they will settle down and form a community, begin filtering our water, and provide a home for other marine life,” said Allison Colden, Maryland senior fisheries scientist with the bay foundation.

“Baltimore is demonstrating it can be a flourishing home for underwater life,” she added.

Construction of the reef was completed last spring, part of a project the bay foundation and the Waterfront Partnership of Baltimore launched two years earlier. The bed of stone that forms the base of the reef is near a similar man-made reef that dates to 1995.

Called the Great Baltimore Oyster Partnership, the project aims to add at least 5 million oysters to both reefs by 2020. Hundreds of volunteers work with the waterfront partnership’s Healthy Harbor Initiative each year to help it grow baby oysters in cages around the harbor, before releasing them atop the reef near Fort Carroll.

Scientists were uncertain how the spat, as baby oysters are known, would fare in some of the Chesapeake’s dirtiest waters. But they hoped the oysters would establish themselves and provide some natural filtration of pollution and nutrients.

They found that about 75 percent of the spat deposited last year survived their first year, growing to an average length of an inch and a half. And while there is some silt on the reef — which can be a smothering hazard for oysters — the bivalves are in some places growing vertically, above the silt.

The Patapsco is off-limits for oyster harvesting, and any dredged up would not be safe for eating. But the oyster reef still provides important habitat for other creatures to live and find food. The scientists have observed 13 different species making use of the one-acre project near Fort Carroll, including barnacles, mussels, mud crabs and grass shrimp.

Adam Lindquist, director of the Healthy Harbor Initiative, said he was not surprised to see signs of a living reef. Scientists have routinely dredged it for samples to see how it’s faring, and had a good idea of the size and abundance of oysters — just not necessarily of all the creatures around them.

But they are still waiting for one more milestone in the recovery of the harbor’s oysters, which once piled up in shoals near Fort Carroll and elsewhere around the bay.

“I think the big question is always whether or not there’s going to be any reproduction on that reef,” Lindquist said. “There’s definitely scientists out there who say, ‘Absolutely not,’ but there’s also scientists out there who say, ‘Life finds a way.’ ”

Either way, the reef is not done growing. Lindquist said he hopes to add another batch of cage-farmed oysters to the reef this fall — the largest one yet.