Those shucked oysters that slid down your throat the other night could have helped keep a flood at bay.
There are scores of great things about oysters, aside from how they taste doused with hot sauce. Oyster colonies provide habitat for wildlife, filter muck out of waterways, stabilize and raise shorelines, and they can bear the brunt of storm surges, helping to spare lowlands from flooding.
What's not so great is the effect of humanity's hankering for the meaty morsels inside the reef-forming shells. Scientists previously concluded that 85 percent of the oyster reefs that once dominated the bays and estuaries of the world have disappeared. Over-harvesting is the main problem, though shoreline development and pollution also contribute.
Oyster reefs can grow almost as fast as acid levels in the gut following a seafood feast.
Oysters relish life in the intertidal range—the portions of shoreline that are exposed during low tides and inundated when tides are high. With sea levels on the rise, there are concerns about whether oyster reefs will keep up with the changing water levels.
The good news out of a study published this week in Nature Climate Change is that oyster reefs can grow almost as fast as acid levels in the gut following a seafood feast. The findings suggest that oyster-reef restoration projects could be powerful tools for reducing flooding as global warming pushes waves ever closer to our doorsteps—though challenges in growing them along shorelines remain to be solved.
Using jackhammers, the scientists drove aluminum piping into oyster reefs in 2010 and 2011 to obtain sample cores from reefs that had been seeded in 1997 and 2000 using bushels of oyster shells in a North Carolina research reserve. Researchers from the University of North Carolina-Chapel Hill and Northeastern University's Marine Science Center analyzed those samples to figure out how quickly the mollusk piles grew. They also used laser scanners to gauge the growth rates of those reefs, and to measure the growth rates of nearby oyster reefs that were created in 2011.
The scientists wrote in their paper that the reefs could double in volume every four years, growing "rapidly in all directions," suggesting that "intertidal reefs have the potential to match even the highest predictions" of sea-level rise forecast by 2100.
"We could construct intertidal reefs near shorelines that provide fish habitat, clean the water, keep up with sea-level rise, and protect the shoreline by buffering erosion and promoting sedimentation," says Antonio Rodriguez, a University of North Carolina associate professor who was involved with the study. "That would be a huge improvement over any artificial shoreline stabilization method."
The next order of business for the researchers, according to Rodriguez: learning how and where to grow reefs along estuary shorelines as quickly as possible. That means growing the oysters alongside marshes, rather than the sand flat-inhabiting reefs that were studied.
"We have constructed reefs adjacent to saltmarsh, but they didn't grow as quickly as the reefs we constructed on sandflats," Rodriguez says. "The saltmarsh landscape is likely providing additional reef stress, like increased predation or decreased flow."