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Scientists say Maryland’s gigantic new oyster reef is a pearl that could save the Chesapeake Bay

MiFarm Oysters Inc. employee Graham Harlan sorts through oysters in a cage during a harvest in Fleets Bay off the Chesapeake Bay near White Stone, Va. (Andrew Harrer/Bloomberg)

The world’s tallest building stands in Dubai. The largest city is in Japan. Brazil’s Amazon is the largest rain forest. And the largest airport sits in the middle of a Saudi Arabian desert.

But Maryland can lay claim to the world’s largest man-made oyster reef. It was finished just days ago, and rests at the watery bottom of Harris Creek on the Eastern Shore, spread across more acres than the national Mall.

Why is this a big deal? The reef in the creek is the foundation of Maryland’s bid to resuscitate its troubled oyster population, overfished to near oblivion for decades and attacked by a couple of killer diseases as vicious as the bubonic plague. Oysters are more than a food that pair well with a dash of lemon and sauce; they are cleaning machines that filter dirty water in the polluted Chesapeake Bay.

That’s why Maryland went through so much trouble to build 10 reefs where fishing isn’t allowed and stock them with more than 1 billion oysters. The state’s accomplishment at Harris Creek the first completed reef with assistance from the Army Corps, the National Oceanic and Atmospheric Administration, Nature Conservancy and others could one day serve as a blueprint for restoring devastated oyster populations nationwide.

[Maryland’s plan to restore Chesapeake Bay oysters involves a lot of hanky panky.]

“People around the country are asking how in the hell did you guys do this?” said Mark Bryer, director of the Chesapeake Bay program for the nonprofit Nature Conservancy. “What was the secret sauce that got you guys to get to a large scale like this? I know we often talk about the bad things, we often don’t talk enough about the good things. This is one of the good things happening in the Chesapeake.”

The story of how oysters arrived at the 330-acre Harris Creek reef has all the charm of a pulp romance novel full of sex, foster children and their search for a good home. It starts at the Horn Point Laboratory run by the University of Maryland’s Center for Environmental Science in Cambridge.

“We are the ones that grow the baby oysters,” said Mike Roman, the lab’s director. In telling the story, he got a little ahead of himself. Before growing the babies, called spat, scientists and technicians at the lab massage their parents into mating in tanks, where females release eggs and males cover them in a spray of sperm. The resulting spat are placed in tanks and spoon fed their favorite food, a variety of algae grown at the lab, until they’re ready to do what oysters do naturally attach to shells.

The shells are a story in and of themselves. Because overfishing has dropped the number of oysters caught in the bay from some 15 million in the 1800s to about 4 million in the 1950s and only about 900,000 in recent years, there aren’t enough new shells for babies grown at the lab to attach to. In 2012 alone, Horn Point’s hatchery produced 1.3 billion spat.

So the Oyster Recovery Partnership of Maryland stepped in to hustle up shells from across the country. Using donations and grants from partners such as the state and the Nature Conservancy, they contracted with businesses in Louisiana to send spent oyster shells to Maryland. On top of that, they knocked on the door of every restaurant in Maryland, Virginia and the District that served oysters and asked them to snatch discarded shells off dinner plates and put them in a special bin with the trash out back that the partnership would pick up.

The shells were trucked to Cambridge and piled into tiny mountains outside the lab. A tractor scoops them up and carries them to a dock off the Choptank River. Roman’s story picks up there.

“We bring millions of larval oysters to the dock, where tanks about the size of a little swimming pools are filled with cages with oyster shells,” Roman said. The spat swim about like home buyers in search of the right shell then glue themselves it. “No way to get them off after that,” said Roman. “We keep them there ’til they get bigger.”

When they’re old enough to venture out on their own, a boat steams up and carries them across the Choptank River to the Harris Creek reef and tosses millions of new inhabitants overboard. Unfortunately, a few are crushed as shells rain down in 20 to 40 feet of water.

The payoff is that oyster reefs blossom into a diverse and thriving ecosystem. They are the ultimate mixed-use development, inhabited by more than 24,500 marine animals that are not oysters — mussels, clams and sea squirts, to name a few. Each of them filter nitrogen, one of three damaging pollutants that plague the Chesapeake.

[The good die young. ‘Dead zones’ find young oysters where they should be safe.]

A 2013 study showed that in one year, a reef seeded with oysters by the state of Maryland — about 130 oysters per square meter — removed 20 times more nitrogen pollution that flows from everything from lawns to farm in fertilizer. Oysters and bivalves scarf up phytoplankton that consume nitrogen. Phyto­plankton produce algae blooms that die, turn into a sticky black goo and suck oxygen — needed by pretty much every inhabitant of bay tributaries — from the water.

Dead zones deplete the bay of life and rob predators such as eagles and osprey of food. As a result of oxygen depletion and other impacts, the bay is in the midst of an aggressive multibillion-dollar, 15-year federal cleanup that ends in 2025.

Scientists “are starting to collect samples to see how much pollution filtration are we getting” from the reef, Bryer said. “At different times of the year they’ll see how much water are they filtering, how many more fish and crabs are we seeing there now that these reefs have been built. We’re going to have a real good sense of what role oysters can play in cleaning up the Chesapeake.”

[Researchers say industrious oysters could clean up Chesapeake]

Another benefit, said Alan Girard, Maryland Eastern Shore director for the Chesapeake Bay Foundation, is that when spat grow to adults in three years and mate by the thousands, their offspring will drift on currents to other reefs. “The Harris Creek sanctuary will serve as a reproductive engine, with the potential to repopulate wide areas outside the creek.”

Girard called it “a significant step in Maryland’s plan to restore what was once a vast underwater food factory and water filtering system. Everyone will benefit from that restoration.”

Read More:

Study calls for halting oyster fishing in Chesapeake Bay

Chesapeake Bay oysters appear to be in recovery mode

To save their depleted species, female blue crabs go the extra mile in the Chesapeake Bay

Leaders of Chesapeake Bay states sign new pact to improve bay’s health

Crabs are bulking up on carbon pollution to become giants