Oysters know how to make their ideal homes—from where to build their reefs to how tall and wide they need to be for optimal breeding, feeding, and protection from predators. Now humans are trying to unravel the mollusks’ real estate secrets.
As the shellfish populations have declined because of changing ocean conditions, pollution, overharvest, and other problems, people have stepped in to build oyster reefs in hopes of giving the species a boost. Concrete, limestone, and recycled oyster shells—collected mainly from restaurants—have proved to be suitable building materials for these reefs, which are attracting oysters and helping them rebuild populations in some places.
And now, to build on early successes in the Gulf of Mexico, scientists are studying how these human-made oyster homes could be improved. In a recent study funded by The Pew Charitable Trusts, marine biologists Sandra Brooke and Adam Alfasso of the Florida State University Coastal and Marine Laboratory conducted an inventory of oyster restoration projects across the Gulf of Mexico and noted that taller reefs were more durable and provided habitat higher in the water column where fewer predators, the best water quality, and other favorable conditions exist. That study also found that projects were more successful when scientists and project managers used computer models to evaluate environmental conditions when selecting potential reef restoration sites.
Another Pew-funded study by scientists in Louisiana—marine ecologist Megan La Peyre of the U.S. Geological Survey, model expert Shaye Sable of Dynamic Solutions LLC, and biologist Danielle Marshall of Louisiana State University—examined models used across the Gulf of Mexico and elsewhere that help find the most suitable sites for new reefs based on salinity levels, temperatures, water currents, and other parameters. This is particularly important in light of ongoing climate change impacts to coastal waters.
That study described the types and aspects of models that can be used in oyster restoration to help give reefs the best chance at success. And the research recommended standardizing and simplifying how models are used within different estuaries to more effectively identify areas predicted to house highly productive spawning reefs. Importantly, those reefs would also be “biologically connected” to other nearby reefs, meaning larvae from one location could easily populate another.
These two recent studies are already helping Gulf of Mexico leaders as they plan to spend more than $4 million from oil spill restoration funds on projects to rebuild oyster reefs in Florida and Louisiana. The knowledge summarized in these reports should continue to pay dividends into the future as resource managers seek more effective methods and optimal areas to enhance oyster habitat across the Gulf.
The Gulf’s shellfish populations have plummeted because of hurricanes, polluted runoff, salinity changes, overharvest, and other problems, including the 2010 Deepwater Horizon oil spill. Money from lawsuit settlements is helping fund many of the Gulf projects.
In Louisiana’s coastal waters, state officials are developing reefs with a focus on areas and methods that the modeling shows will provide long-term stable habitat. At those reefs, harvest will be prohibited to boost breeding. Scientists expect that as the oysters grow and reproduce their larvae will travel to nearby reefs and increase populations where harvest is permitted. And in Florida, officials are rebuilding reefs as part of projects to restore several areas including Apalachicola Bay, which once accounted for 90% of the Sunshine State’s oyster harvest.
Healthy oyster reefs provide habitat for diverse marine life and benefit people by filtering excessive nutrients from water and buffering coastlines from storm surge and flooding. Oysters also support jobs—for oyster harvesters, restaurant staff, and others—as well as recreational activities such as fishing that rely on healthy reefs for habitat.
Gulf states likely will take on more oyster reef-building projects in coming years, especially given the hundreds of millions of dollars from oil spill restoration and other funding sources that they have for these efforts. Research studies, such as the Pew-funded reports, can provide the scientific guidance needed to help create the most inviting homes for Gulf oysters.
Chad Hanson works on the conserving marine life in the U.S. project.