Artificial Oyster Reefs Could Revive Ocean Health

For some people, oysters are just a tasty appetizer best served with a squeeze of lemon. But they also play a key role in keeping oceans health. Some wild oyster populations, though, have plummeted.

So the Massachusetts Audubon Society is building artificial oyster reefs at its Wellfleet Bay wildlife sanctuary on Cape Cod. The hope is to learn new ways to revive oyster beds nationwide. WBUR's health/science reporter Sacha Pfeiffer visited the sanctuary and has this story.

Just a short walk from Wellfleet Bay, Bob Prescott kicks a huge mound of shells.

"You can see lemons in here. There's even a fork up in here. Cocktail sauce on that one."

The shells are leftover from the Wellfleet OysterFest held earlier this month. The Massachusetts Audubon Society is now using them to try to save the very species that's been threatened in part by human consumption.

"We're going to zip-tie each oyster to a mat and see if we can get next year's baby oysters to grow on these shells."

Fifty thousand oyster shells that will be placed on the tidal flats of Wellfleet Bay next June. Prescott, the sanctuary director, hopes young oysters will glue themselves to this artificial reef and form colonies. Mass Audubon put a different type of homemade reef in the bay last June — and it's already attracting hundreds of young shellfish.

"You know, some people say watching oysters grow is like watching paint dry. But it's really just fun to see nothing in July and then you come out there in August or September and October and all of a sudden there are all these baby oysters."

Baby and adult oyster populations are relatively plentiful in parts of Wellfleet. But they've died out at the wildlife sanctuary and in other parts of the country from overfishing, pollution, and disease. And when oysters die, we lose much more than a source of food.

"More and more it's being recognized that these are what we call keystone species; they're crucial parts of the ecosystem."

That's Bill Walton, a Cape Cod shellfish biologist. He explains oysters are crucial because they can filter 30 gallons of water a day. They also form reefs that attract other marine creatures. And they help prevent coastal erosion. This is the first time Massachusetts is trying an oyster restoration. So Mass Audubon is teaming up with a national conservation group and the federal government to see which types of artificial reefs work best.

SOUND OF A SHELL BEING USED TO TAP AN "OYSTER BLOCK"

At the Boston office of the Nature Conservancy, marine ecologist Jennifer Greene uses a shell to tap on something called an oyster block. This is another kind of manmade reef. It's made of cement mixed with shells and it weighs almost 30 pounds.

"It looks kind of like a concrete cinder block, but when you look at this under the microscope what you see is all these pores in the cement."

Young oysters may settle into those pores. That keeps them safe from predators until they develop into adults.

"It's kind of like an English muffin — you know, lots of different nooks and crannies, lot of places for things to grow, and then you'd get thousands of oysters on here. And it would take about three years, probably, to look like a natural reef area."

These oyster blocks will be part of Wellfleet's natural-looking artificial reef. So will the shell mats made from the OysterFest oysters, and so will other experimental structures. The goal is to seed new oyster colonies. Mass Audubon will monitor the reefs to learn which ones draw the most oysters and what other types of wildlife they attract. It will then use those lessons learned in places where oysters are dying.

And if all goes well, local fishermen will harvest some of the shellfish in three years. That means more of those famous Wellfleet oysters, which Bill Walton says taste like fine wine.

"It's got that really crisp salty flavor, and then when you finish the oyster it's got a really sweet finish to it. It's almost like a cucumber-type finish to the end."

Whether they're eaten or not, the oysters growing on Wellfleet's artificial reefs could keep the harbor healthy for years to come.