Southeast Coast Estuaries: National Coastal Condition Assessment 2015

Setting

The coastal resources of Southeast Coast region are diverse and extensive, covering an estimated 4,600 square miles. The region extends from the North Carolina-Virginia Border through the Biscayne Bay estuary system at the southern tip of Florida. The provinces of this region include the Carolinian Province, which extends from Cape Henry, VA, through the southern end of the Indian River Lagoon, and part of the West Indian Province, which runs along the east coast of Florida from the Indian River Lagoon through Biscayne Bay. The Southeast Coast is dominated by barrier island, lagoon and salt marsh systems but also includes blackwater rivers, brackish waters of the Intracoastal Waterway and busy shipping ports. These estuaries and the surrounding coastal habitats serve as important stopovers for migratory birds along the Atlantic Flyway as well as nurseries for fish and other animals. The highly productive ecosystems of Southeast estuarine waters contribute to commercial and recreational fishing.

The Southeast Coast provides a wealth of economic and ecosystem services that sustain local economies and quality of life. These services include storm-surge and sea-level protection, maritime transportation and trade, commercial and recreational fisheries, and tourism. While the populations of ten counties bordering Albemarle and Pamlico Sounds in North Carolina have decreased, the aggregated populations of coastal shoreline counties of the Southeast region have grown at rate exceeding of about 12% since 2010¹.

Biological Condition

The NCCA found that in 2015, biological condition was good in 62% of the estuaries in the Southeast, according to the M-AMBI marine benthic index. This is lower than the overall national estimate of estuaries in good biological condition of 71% and is not significantly different from the proportion of Southeast area rated good from 2010 to 2015.

Eutrophication Index

The eutrophication index, which examines the potential for estuarine area to undergo social eutrophication based upon measurements of nutrients, chlorophyll a, dissolved oxygen and water clarity, found that 17% of Southeast estuarine area was in good condition, 71% of area was in fair condition and 10% in poor condition. While this indicates that the Southeast is more likely to experience eutrophication than the country as a whole, they are not significantly different than the conditions in the Southeast in 2010. There is a need for continued improvements in nutrient management in waters that flow into estuaries of the Southeast.

Sediment Quality Index

About 84% of the Southeast estuarine area had good sediment quality based on measures of chemical contaminants found in sediments and laboratory tests of toxicity. This is better than the rest of the estuarine area in the continental US in 2015 but is not significantly different from the Southeast sediment quality in 2010.

Ecological Fish Tissue Contaminants

Ecological fish tissue contamination is degraded in the Southeast with 38% of waters in poor condition and 35% in fair. Only 15% of the area is rated good. These estimates do not represent statistically significant change in the proportion of area rate good, fair or poor from 2010 to 2015. In the Southeast, 12% of waters were not assessed for this indicator because suitable fish were not caught. This rate of unassessed area is similar to the national average of about 11%. It is important to note that this assessment of potential for adverse effects applies only to wildlife that eat fish and does not apply to people.

Human Health Indicators

More than 99% of Southeast estuarine waters have low levels of bacteria and microcystins and are safe for recreation.

Because field crews were unable to catch fish that were suitable for human consumption, 75% of the estuarine area in the Southeast was unassessed for mercury contamination in fish fillet plug samples; no estimate of area with mercury contamination either above or below the 300 parts per billion human health consumption benchmark is available for that proportion of the Southeast. Less than 1% of Southeast estuarine area have fish with concentrations of mercury in fillet plug samples exceeding the human health benchmark while fish from 24% of the area posed little to no risk for human consumption. In order to address the large proportion of area that was unassessed, the NCCA implemented new fish fillet plug sampling procedures in 2020.

A fish fillet “plug” is a small biopsy sample taken from a live fish. The fish is released after sampling.

PCBs and PFOS in whole fish fillets were only assessed in Great Lakes nearshore waters.

Recreational anglers should consult local fish consumption advisories before eating their catch.

To access more indicator graphics please visit the interactive NCCA dashboard.​