Albemarle-Pamlico Sounds
The Albemarle-Pamlico Sound is a significant estuarine system located in the mid-Atlantic coastal region of North Carolina, recognized as the second-largest estuary in the United States, following the Chesapeake Bay. This unique ecosystem is shielded from the Atlantic Ocean by the Outer Banks and is characterized by a mix of freshwater and saltwater, which creates diverse habitats, including wetlands and marshes. Covering a watershed of about 31,000 square miles, it drains rivers from 36 counties in North Carolina and 16 in Virginia, supporting over seventy-five species of fish and shellfish. The sound is an essential area for commercial and recreational fishing, contributing significantly to the local economy.
However, the Albemarle-Pamlico Sound faces several environmental challenges, including water quality issues stemming from land-use activities, nutrient loading, and rising sea levels. Excessive nutrients, particularly nitrogen, have led to harmful algal blooms and fish kills, affecting both aquatic life and human health. Additionally, the area is threatened by global warming, which is causing sea-level rise at an alarming rate, further complicating conservation efforts. The impact of these changes on the local ecosystem and economy, particularly tourism and fishing, raises important concerns for the communities that rely on this vital resource.
Albemarle-Pamlico Sounds
- Category: Marine and Oceanic Biomes.
- Geographic Location: Eastern region, United States.
- Summary: The Albemarle-Pamlico Sound is the second-largest estuary system in the United States, providing habitat for fish and shellfish. Land-use activities pose challenges to water quality and aquatic resources here.
The Albemarle-Pamlico Sound is located in the mid-Atlantic coastal region of North Carolina and is protected from the Atlantic Ocean by a sliver of sandy barrier islands known as the Outer Banks (and their easternmost extension, Cape Hatteras). It is the second-largest estuary system in the United States, after the Chesapeake Bay. The sound supports diverse, abundant fish and shellfish populations; the Albemarle and Pamlico regions historically developed around these natural resources. Commercial and recreational fishing are important components of the social and economic vitality of the coastal area. The water quality of the Albemarle-Pamlico Sound, however, has been influenced by land use in the watershed.
The watershed contributing to the sound is approximately 31,000 square miles (80,290 square kilometers), composed of more than 9,000 miles (14,484 kilometers) of freshwater rivers and streams, as well as 1.5 million acres (607,028 hectares) of estuarine habitat. The average depth in the sound is 13 feet (4 meters). The watershed drains 36 counties in North Carolina and 16 counties in Virginia. Six major river basins flow into the sound: The Pasquotank, Chowan, Roanoke, Tar-Pamlico, Neuse, and White Oak Rivers provide freshwater flow to the sound, which is connected to the Atlantic Ocean by three inlets.
This mix of freshwater and saltwater creates diverse habitats that include bald cypress wetlands; brackish, freshwater, spartina, and salt marshes; abundant submerged aquatic vegetation; forested wetlands; and an interesting, unique habitat referred to as pocosin or southeastern shrub bog. Pocosin is a Native American term that means “elevated or high swamp.” Pocosins accumulate layers of peat, an infertile layer of organic material on the bottom of the wetland. This layer of peat results in plant growth that is less robust than typical growth in more fertile conditions. The Albemarle-Pamlico Sound watershed supports more pocosin habitat than any other place in the world.
Fish Habitat and Nursery
The Albemarle-Pamlico Sound provides habitat and nursery waters for more than seventy-five species of fish and shellfish. Salinity is one of the major influences on the distribution of fish species in the sound; it varies constantly, ranging from nearly 0 percent in the lower portions of the rivers to 25 percent near the inlets on the Outer Banks. Salinity is affected by freshwater inflow, season, tides, and wind direction and intensity.
Fish species that are important commercially and recreationally in the sound include striped bass, flounder, speckled trout, redfish, menhaden, and croaker. Up to 90 percent of the commercially important finfish species in the greater mid-Atlantic region rely on the estuarine habitats of the Albemarle-Pamlico Sound for spawning, development, and forage. Shrimp, blue crabs, oysters, and scallops are additional commercially and recreationally valued species in the estuary.
The sound is habitat for a fish community that has evolved reproductive strategies using the rivers that enter the sound and the tidal currents that originate in the Atlantic Ocean. Catadromous fish species such as the American eel live in the freshwater rivers and creeks in the Albemarle-Pamlico Sound watershed as adults. The eels migrate from freshwater through the sound to the Atlantic Ocean and on to the Sargasso Sea to reproduce. The immature eels, or elvers, use ocean currents to return to the sound to develop; as they mature, they use the sound for foraging and refuge
Anadromous fish species in the sound include striped bass, American shad, and several herring species. Anadromous fish live in the saltwater habitat of the Atlantic Ocean and migrate through the sound to spawn in freshwater rivers and creeks. The reproductive strategy of these species is to spawn in the water column so that the fertilized eggs drift with the currents downstream to the sound. The larval fish develop and grow in the sound before migrating back to the Atlantic Ocean. Other species—such as blue crab, gray trout, red drum, spot, flounder, and shrimp—spawn in the ocean. Tidal currents carry the eggs and larval life stages into the sound to find food and protection from predators.
Water-Quality Challenges
The Albemarle-Pamlico Sound faces several complex water-quality issues. The Virginia Department of Environmental Quality (DEQ) identified water-quality problems that negatively affect aquatic resources in the watershed; it determined that nearly 59 percent of the freshwater streams in Albemarle County are affected by land-use activities that impair water quality, which translates to other counties and regions that share the same water. The primary causes of water-quality impairment in the basin are excessive sediment; fecal coliform bacteria; and excessive nutrient loading, especially nitrogen that derives largely from runoff of the region's extensive pig farming and other agricultural operations. These conditions result in harmful algal blooms, anoxic conditions, and fish kills.
Nutrients are substances that help plants and animals grow. Two nutrients that are critical for development are nitrogen and phosphorous; these nutrients are also present in plant fertilizer and animal and human waste. Nutrient loading in the watershed has been widely linked to agricultural and urban runoff, atmospheric deposition in the form of acid rain, and point and nonpoint discharges that include sewage-treatment-plant effluent.
The effects of nutrient loading often promote abundant algal blooms, which deplete the water column of dissolved oxygen. Low dissolved oxygen results in stressed environmental conditions that can kill fish directly or that allow bacteria and viruses to more readily infect finfish and shellfish populations. Excessive nutrient loading has resulted in periodic fish-consumption advisories in the sound to protect human health. This is particularly an issue as 90 percent of North Carolina's commercial fishing catches took place in the Pamlico Sound as of 2019, rendering it an important part of the state's economy. However, according to commercial fishermen in 2021, they were struggling to earn a living fishing due to the state's many regulations, which affect the size of catches as well as the seasons when they can fish. In 2021, commercial fishing contributed $300 million to the economy and employed at least 5,000 people. On a larger scale, the Albemarle-Pamlico Estuarine System (APES) is responsible for at least 80 percent of the commercial and recreational fish caught in the US Southeast Atlantic. Furthermore, the Outer Banks area is also where much of North Carolina's tourist activity takes place, and as such there has been concern about the effect of poor water quality on tourism revenue. In 2021, fecal contamination closed some beaches. Of the 210 beaches in North Carolina, eight-seven were deemed unsafe for at least one day when the testing took place.
Sea-Level Rise
Another looming threat to the Albemarle-Pamlico Sound is a combination of sea-level rise due to global warming, and land subsidence that is notable along the mid-Atlantic coast. Recent studies have confirmed that the coastal area from Cape Hatteras to north of Boston is logging sea-level rise at three to four times the global average. With the cape and its associated barrier islands of the Outer Banks under such pressure—and the concomitant higher storm surges and heavier hurricane threat—conservationists must plan for responses to the potential of increased salinity in the delicately balanced biome of the sound.
Bibliography
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“Current Conditions.” Albemarle County, www.albemarle.org/government/community-development/learn-more-about/stream-health/current-conditions. Accessed 11 Oct. 2024.
Forsey, Madison. "Commercial Fishermen Say They Can't Stay Afloat Under Regulations." WCNT, 13 May 2021, www.wnct.com/local-news/commercial-fishermen-say-they-cant-stay-afloat-under-biased-regulations/. Accessed 11 Oct. 2024.
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Sallenger, Asbury H. Jr., Kara S. Doran, and Peter A. Howd. “Hotspot of Accelerated Sea-Level Rise on the Atlantic Coast of North America.” Nature Climate Change 2, no. 6 (2012).
United States Environmental Protection Agency (EPA). Ecosystem Services Research Program (ESRP) Albemarle-Pamlico Watershed and Estuary Study (APWES) Research Plan. Washington, DC: EPA Office of Research and Development, 2010.
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