The waters harbor much of the world's last remaining productive natural oyster beds, but BP PLC's April 20 oil well blowout dumped millions of gallons of crude into the Gulf and dealt yet another blow to the once bountiful habitat.
This weekend, volunteers descended on Mobile Bay with 23,000 bags of oyster shells aimed at eventually creating 100 miles of new oyster reefs near the shoreline. The goal is to help replenish oyster reefs that promote new growth, help protect delicate salt marshes and sea grasses, and act like coral in the tropics to provide habitat for numerous marine species.
It's one of the first coastal restoration projects since the oil spill sent thick crude washing into estuaries and onto beaches.
Biologist Rob Brumbaugh of The Nature Conservancy, which helped organize the event, said studies show that the world has already lost 85 percent of its natural oyster reefs, but the Gulf of Mexico remains a bright spot, even after the oil spill.
"Certainly the oil spill was a wake-up call and a serious impact that we have to recover from, but frankly, there's been 100 years or more of oyster reefs and salt marsh and sea grass loss," he said. "That's the larger thing that we're trying to recover from and set a new course."
About 350 volunteers came to lay 10-pound bags of oyster shells in a neat line several feet high on mud flats about 150 feet offshore to create new reefs across Mobile Bay.
The U.S. Fish and Wildlife Service contributed about $70,000 to the project, which was approved before the oil spill but was delayed until the waters were relatively clear of crude. Funding also came from the National Oceanic and Atmospheric Administration and donations. The total cost is expected to be about $100 million, and it likely will take up to five years to complete if funding continues.
Brumbaugh said the oysters also help keep waterways clean. Each oyster can filter up to 50 gallons of water a day.
"If you remove all these oysters from the estuaries, you've essentially unplugged the aquarium. It's like turning off your pool filter and expecting it to stay in good shape," he said.
Chesapeake Bay oysters also have been devastated and are at only about 1 percent or 2 percent of their historic highs, hit by years of disease, pollution and overharvesting.
Oysters along the entire Gulf Coast were hit hard in the spill's aftermath, prompting closures and delays of harvesting seasons that are part of the region's economic lifeblood.
Louisiana saw scores of oyster die-offs from the summer of oil, in part because officials flooded some areas with fresh water to try to keep crude out of sensitive bays and estuaries. That upset the balance of fresh and salt water, killing oysters. In Mississippi, oyster mortality rates were so high after the spill, the state did not allow a dredging season for the first time in more than 20 years.
It instead opted for a limited tonging season, a much more laborious process of culling oysters from the sea floor by hand using a rake. State officials have said it's unclear if the oyster deaths were directly caused by the oil or a combination of factors, including unusually warm summer waters.
"It's just time we start doing something more to reverse the problem," said Dan Everson of the U.S. Fish and Wildlife Service, who helped with the Mobile oyster reef restoration project this weekend.
A U.S. presidential panel created to investigate the oil spill recently recommended that 80 percent of fines and penalties eventually levied against responsible parties, a number that will likely be in the billions of dollars, be dedicated to Gulf Coast restoration.
Casi Callaway, executive director of the environmental group Mobile Baykeeper, said the spill's aftermath could have a bright spot: More money dedicated to wetlands projects and other efforts.
"The oil disaster was big, the biggest environmental disaster in our country," Callaway said. "But what we have with these ideas is an opportunity to create some of the biggest environmental restoration projects in our country."