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Sanctuaries Last Best Hope For Oysters, Scientists Say

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A diver pulls up chunks of oyster reef.
Sabri Ben-Achour
A diver pulls up chunks of oyster reef.

By Sabri Ben-Achour

Maryland is drawing up plans to set aside 25 percent of all Oyster habitats in the bay as sanctuaries where they can't be harvested. It’s part of a broader effort to bring back what scientists call the coral reefs of the Chesapeake.

It's caused controversy among watermen, who say it's a grand experiment at their cost. But scientists and environmentalists insist that if oysters can just be left alone, they might start to come back, and bring a whole bunch of other creatures with them.

On the Severn River, just south of the bridge where Route 50 connects D.C. and Annapolis, divers are searching the bottom. Chesapeake Bay Foundation researcher John Allen reports back over an intercom.

"It’s not too bad, but it’s the Severn," says Allen.

They’re looking for the oysters they planted five years ago. The water is cloudy, and they spend a few minutes looking around.

There was a time when this water was crystal clear, and when you didn’t have to search for oysters, you could practically trip over them. In fact, John Smith practically did.

When he first sailed the Bay in 1607, he wrote that reefs were so high they stuck out of the water. But by 1920, three quarters of the bay’s reefs had been wrenched from the water and harvested for meat. Old photos show piles of shells hundreds of feet high. Even so, oysters hung on for a few decades.

"When I was a kid, oyster reefs were everywhere. Back in '72 or so, minute I put my head underwater, it was 30 feet of water, I could see oysters on the bottom," says biologist Mutt Merritt. His lab at Horn Point hatched the oysters that the divers are looking for. "You go down and they were just one on top of each other. They’re just very different out there now."

But midway through the 20th century, diseases from abroad started to wipe them out. Sediment started to bury them. And pollution made things worse. Now they’re at 1 percent of what they used to be. Back on the bottom of the river, the divers have found something.

"Alright we got ‘em."

They come up to the surface and bring with them volleyball-sized clumps of oysters.

"They’re not super packed down there, but I’ve dove in all sorts of portions of the bay and there’s a pretty good number of oysters down there in the Severn River now thanks to restoration," says John Allen, a researcher with the Chesapeake Bay Foundation.

He hands a basketball-sized mass of oysters to Stephanie Westbay, a fisheries scientist with the Chesapeake Bay Foundation.

"You can see now they’ve grown into these really big healthy clumps of oysters, a few dead oysters but mostly alive," says Westbay.

And a lot of other creatures came up with the bits of reef; they slither out from the nooks and crevices in between the shells.

"If you look closely here on the deck you can see all kinds of worms and Mud crabs and little shrimp kicking around here, so they really do provide spectacular habitat," she says.

By offering a place to live and hide to those creatures, the reef creates food for bigger creatures.

"Striped bass, Blue crabs, a variety of fish that actually feed on them," says Bruce Goldsborough, director of the fisheries program with the Chesapeake Bay Foundation. "So you’re actually fueling the food web. So you get a lot more of those fish that we catch and have economic value for us, that are able to find food and habitat."

He says in other sanctuaries, the reefs have attracted fish like Black Sea Bass, which haven’t been seen in the bay for decades.

"That’s why the reef community is not about having a pile of oysters, but restoring the functioning of the whole ecosystem," he says.

But it’s definitely an uphill battle. The EPA has spent over $6 billion trying to restore the oyster population, but results are spotty.

Runoff from cities and farms stirs up sediment that can easily cover up and kill fledgling reefs like the one beneath the boat. Low-oxygen water from the Bay’s notorious dead zones can suffocate them. And the diseases that were the last nails in the coffin for many oyster populations in the bay continue to plague this cornerstone species, though some oysters are gradually building resistance.

Scientists say the sanctuaries, where the oysters can be left to build that resistance as well as build reefs, are the last best hope these creatures have.

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