Since 1986, NOAA’s Mussel Watch Program has monitored the nation’s coastal waters for chemical contaminants, an effort that now includes trace metals, legacy contaminants, and contaminants of emerging concern. In 2026, the program collected oyster samples (Crassostrea virginica) from a network of 52 sites on the South Atlantic coast. Results from this study will support a better understanding of the sources, fate, and transport of contaminants in the region and will fill important data gaps for local stakeholders.
Why We Care
Estuaries along the nation’s South Atlantic coast, important both ecologically and economically, are experiencing the impacts of development.
Chesapeake Bay — the largest estuary in the continental United States, with a watershed that covers parts of six states — is home to critical wildlife habitats and important fisheries. However, centuries of land development and agricultural and industrial activities have added thousands of pollutants and excessive sediment to runoff, compromising water quality in the bay. Charleston Harbor in South Carolina, a rapidly growing container port, has undergone extensive dredging for decades, potentially contaminating local waterways. Florida’s Atlantic coast includes densely populated cities and a range of land uses, which can yield contaminants that end up in aquatic environments.
The high productivity of these ecosystems along with their high potential for contamination make these coastlines important to monitor. Previous studies in the region have investigated legacy contaminants (e.g., trace elements, polychlorinated biphenyls (PCBs), organochlorine pesticides, chlordane, and polycyclic aromatic hydrocarbons (PAHs)), and have helped managers limit the impact these pollutants have on coastal ecosystems. However, such efforts are lacking for the increasing number of new and unregulated compounds known as contaminants of emerging concern (CECs), many of which are known to be harmful to people, animals, and the environment.
In response to resource managers’ concerns about the extent and impact of both new and old chemical stressors, the Mussel Watch Program conducted a basin-wide survey of the South Atlantic coast in 2026 to assess the magnitude and distribution of a suite of CECs, metals, and legacy contaminants in the region.
What We Are Doing
The Mussel Watch Program is a national chemical contaminant monitoring program that operates through NOAA’s National Centers for Coastal and Ocean Science (NCCOS). The program was established in 1986 and uses an ecosystem-based approach to monitoring, which entails measuring the concentration of chemical contaminants in sediment and tissue of indigenous bivalves, such as oysters and mussels, as a way to evaluate local environmental quality. Bivalves are used as indicator organisms for chemical contaminants in their local environments because they are immobile and they bioaccumulate contaminants in the water as they filter feed.
The Mussel Watch Program currently analyzes sediment and bivalves for both legacy contaminants and contaminants of emerging concern (CECs). Legacy contaminants have been monitored within the Mussel Watch Program since 1986 and include compounds such as chlordanes, chlorobenzenes, dichlorodiphenyltrichloroethane (DDT), dieldrins, endosulfans, hexachlorocyclohexanes (HCHs), butyltins, PAHs, and PCBs. The monitoring of CECs began in 2009 and includes contaminants such as alkylphenols, alternative flame retardants, current-use pesticides, (per- and polyfluoroalkyl substances (PFASs), polybrominated diphenyl ether (PBDEs), polybrominated biphenyls (PBBs), and pharmaceuticals and personal care products. In general, CECs are minimally regulated, not commonly monitored, but potentially toxic chemicals that are finding their way into the environment.
In 2026, the Mussel Watch Program assessed a network of 59 sites on the South Atlantic coast to be analyzed for the full suite of metals, legacy contaminants, and CECs. In this survey, 49 samples of Crassostrea virginica and 3 samples of Crassostrea rhizophorae were collected across the South Atlantic coast, spanning from the Chesapeake Bay, Maryland, through the Florida Keys, Florida, and including Puerto Rico following the Mussel Watch Program standard protocols. These sites were selected from long-term Mussel Watch Program monitoring sites. Although 59 sites from the region were identified to be sampled, only 52 sites yielded enough oysters for laboratory analyses due to collaborator support and oyster abundance at historic locations.
The National Mussel Watch Program designed the 2026 South Atlantic coast regional chemical stressors survey in collaboration with the NOAA Oxford Cooperative Laboratory (COL), the Maryland Department of the Environment (MDE), the Virginia Institute of Marine Science (VIMS), the Virginia Marine Resources Commission, the University of North Carolina Wilmington (UNCW), the NOAA Beaufort Laboratory, the National Parks System Cape Lookout, the National Parks System Cape Hatteras, the North Carolina Department of Environmental Quality (NCDEQ), the South Carolina Department of Natural Resources (SCDNR), the Georgia Department of Natural Resources (GADNR), the NOAA Hollings Marine Laboratory (HML), Florida International University (FIU), the Matanzas Riverkeeper, the St. Johns Riverkeeper, the NOAA Jobos Bay NERR, and Puerto Rico Departamento de Recursos Naturales y Ambientales (PR DRNA).
Benefits of Our Work
This study supplies much-needed data to the National Mussel Watch Program and to local stakeholders and managers on the South Atlantic coast and informs water quality data used by coastal resource managers to develop effective, long-term policies to protect ecosystem services provided by the South Atlantic coast.