How scientists clean up rivers with grasses and oysters

One hundred miles north of Philadelphia, the Billion Oyster Project has been restoring the seashells in New York Harbor since 2010, hiring more than 10,000 volunteers and 6,000 students for the project. Oyster farms are being established in Belfast Lough, Northern Ireland, where until recently it was thought to have been extinct for a century. And a hatchery 30 miles west of Chicago has dispersed 25,000 clams into area waters, boosting populations of common freshwater clam species.

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

Scientists emphasize that these projects must be implemented alongside strategies to further contain pollutants, mainly excess nutrients from sewage and fertilizers, flowing into our waterways – still the most important step in improving water quality. After several decades of planting aquatic vegetation in the Chesapeake Bay, for example, scientists say the modest increase in plants is largely due to nature recovering from a reduction in nutrient loads.

And any human intervention in a complex ecosystem raises a variety of compelling concerns, such as how to ensure sufficient genetic diversity and monitor competition for food and resources. Scientists say that in many cases they learn as they walk.

In areas where the natural environment is improving, the return of mussels and aquatic plants can provide a lasting foundation for entire ecosystems. And restoration initiatives are an active form of stewardship that connects people to their waterways and helps them understand the ecosystems we depend on for our survival.

Up to five years Previously, the extent of the wild celery grass meadows in the Delaware estuary was a mystery. Many scientists considered the water quality unsuitable, and since the estuary contains a lot of sediment and waves with the tides, the plants were not visible on aerial photographs.

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

Finding healthy grass beds was exciting, says Kelly Somers, senior watershed coordinator for the EPA Mid-Atlantic Region, because the plant is an indicator of water quality. The EPA’s research, which is accessible via online maps, has been particularly helpful to the Upstream Alliance’s restoration work, says founder and president Don Baugh, since most of the research on wild celery grass has come from elsewhere — primarily the Chesapeake Bay. Wild celery and other aquatic plant species have been restored there for more than 30 years.

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