How Scientists Are Cleaning Up Rivers Using Grasses and Oysters

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One hundred miles north of Philadelphia, the Billion Oyster Project has been restoring bivalves to New York Harbor since 2010, involving more than 10,000 volunteers and 6,000 students in the project. Oyster nurseries are being established in Belfast Lough, Northern Ireland, where until recently they were thought to have been extinct for a century. And a hatchery 30 miles west of Chicago has dispersed 25,000 mussels into area waterways, boosting populations of common freshwater mussel species.

Underwater vegetation restoration projects have been underway for years in the Chesapeake Bay and Tampa Bay, and more recently in California, where seagrass species are in steep decline. (Morro Bay, for example, has lost more than 90 percent of its eelgrass beds in the past 15 years.) The California Ocean Protection Council’s 2020 Strategic Plan to protect the coast and ocean of California aims to preserve the only 15,000 acres of known seagrass meadows and cultivate 1,000 more acres by 2025.

Scientists stress that these projects must be implemented alongside strategies to continue curbing pollutants, primarily excess nutrients from sewage and fertilizers, flowing into our waterways, still the most critical step to improving the quality of the water. After several decades of aquatic vegetation plantings in the Chesapeake Bay, for example, scientists say the modest increase in plants is largely due to the restoration of nature after a reduction in nutrient pollution.

And any human intervention in a complex ecosystem raises a number of compelling concerns, including how to ensure sufficient genetic diversity and control competition for food and resources. Scientists say, in many cases, they are learning as they go.

Still, in areas where the natural environment is improving, recovering bivalves and aquatic plants can create a lasting foundation for entire ecosystems. And restoration initiatives are an active form of stewardship that connects people to their waterways, helping them understand the ecosystems we depend on for our survival.

Up to five years ago, the extent of wild celery beds in the Delaware estuary was a bit of a mystery. Many scientists believed that the water quality was not adequate, and because the estuary contains a lot of sediment and debris with the tides, the plants were not visible in aerial images.

But in 2017, EPA researchers began surveying by boat for submerged vegetation and were surprised to find the plant thriving in parts of a 27-mile stretch of the Delaware River from Palmyra, New Jersey, through Camden and Philadelphia, to Chester, Pennsylvania. This is the only section of the river designated by the Delaware River Basin Commission as unsafe for “primary contact recreation” — activities such as water skiing, kayaking and swimming.

The discovery of healthy grass beds was exciting, says Kelly Somers, senior watershed coordinator for EPA’s Mid-Atlantic Region, because the plant is an indicator of water quality. EPA research, accessible via online maps, has been especially helpful to the Upstream Alliance’s restoration work, says founder and president Don Baugh, because most of the research on wild celery comes from from other places, mainly from the Chesapeake Bay. The restoration of wild celery and other aquatic plant species has been underway there for more than 30 years.

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