Click below to learn more about the environment of The Sounds.
The size of the Albemarle-Pamlico estuary
An estuary is a body of water formed where saltwater and freshwater meet and mix. Estuaries are vital nursery areas for many fish, and provide other environmental benefits as well. The Albemarle and Pamlico sounds form the second largest estuarine system in the United States, smaller only than the Chesapeake Bay (but bigger than Long Island Sound, San Francisco Bay, and other well-known estuaries). The Albemarle-Pamlico system includes all the contiguous waters behind the Outer Banks, including Core Sound, Croatan Sound, Roanoke Sound, and Currituck Sound. The sounds themselves cover an area of some 2,900 square miles. The entire Albemarle-Pamlico watershed—which includes all the land area drained by all the rivers that run to the sounds—covers over 30,000 square miles in North Carolina and Virginia.
Three rivers deliver most of the freshwater that flows to the A-P: the Neuse and Tar-Pamlico rivers, which start in the northern Piedmont of North Carolina; and the Roanoke River, which starts in the foothills of southwestern Virginia. Freshwater also comes from 15 relatively short “blackwater” rivers that begin in swamps on the coastal plain.
For more information on the Albemarle-Pamlico estuary, go to www.apnep.org. Also go to www.estuaries.org for general information about estuaries.
Salinity
The salinity (salt content) of ocean water is about 35% (or roughly 35 grams of salt per liter of water). The salinity of the Albemarle-Pamlico estuary is about 25% near inlets on the Outer Banks, and gradually decreases the farther west you go in the sounds, generally reaching 0% (freshwater) around the towns of Washington and Edenton.
Salinity in the estuary changes constantly due to weather and other factors, rising during droughts because less freshwater flows to the estuary from rivers, and decreasing during periods of heavy rains. Winds also play a role, with easterlies pushing saltwater from the lower estuary upstream, and westerlies forcing freshwater farther downstream. Seasonal changes in plant activity impact salinity levels as well.
For information on salinity and other measurements of water quality in the Pamlico estuary, go to www.esb.enr.state.nc.us/prrt.html
Wind Tides
The lunar pull that causes high and low tides in the ocean barely affects the Albemarle and Pamlico sounds, but the A-P’s water levels can be dramatically altered by wind. Since our sounds and coastal rivers are wide and shallow, strong easterly winds push a lot of water inland and cause shoreline flooding without a drop of rain. Likewise, strong winds from other directions can turn coastal rivers into temporary mudflats by pushing water down to the sounds.
Environmental Concerns in the A-P Estuary
The Albemarle-Pamlico system is the least urban of America’s major estuaries and perhaps the least polluted, but still has its problems. Below are brief explanations of the A-P’s biggest environmental issues:
Sedimentation
Sedimentation is the erosion or runoff of soil into waterways. It occurs naturally, but clearing land for development and agriculture has caused an excess in many rivers of the Albemarle-Pamlico. Too much sediment clouds water (called turbidity), which hurts fish by smothering habitat, reducing oxygen, and stressing health. Though it is the single biggest cause of water-quality degradation in the A-P, sedimentation is easily reduced by leaving buffer strips of vegetation between waterways and cleared areas.
Nutrient Overloading
This refers to the introduction of excessive nutrients into waterways. Nutrients (such as nitrogen and phosphorus) are natural and necessary for plankton growth in waterways, but an overload causes damaging algae blooms. As the blooms die, oxygen-using bacteria decompose them. Heavy blooms cause these bacteria to multiply rapidly, resulting in a depletion of oxygen in the surrounding water that can kill thousands of fish. Excess nutrients get into waterways from sewage plants, animal wastes, and agricultural/residential fertilizers. Again, vegetated buffer strips are a simple and effective way to filter out nutrients before they reach the water, but many landowners don’t like the idea of leaving 30-50 feet of shoreline in a natural state.
For information on measurements of water quality in the Pamlico estuary, go to www.esb.enr.state.nc.us/prrt.html
Habitat Loss
The loss of shelter, food and space for animals is referred to as habitat loss. Marshes, underwater grass beds and shallow areas along shorelines are critical habitats for young fish in the estuary. Without these sources of food and shelter, fewer fish grow to reproductive maturity. Bulkheads for waterfront development have destroyed many miles of estuarine shoreline in the last 30 years, and continue to expand despite regulations designed to curb them. On land, thousands of acres of swamps, forests, and other natural places are converted to residential development, agricultural fields, and other uses each year. As these areas shrink, animal populations become fragmented, food sources are overused, and more creatures are killed through traffic accidents or deliberate taking. The A-P estuarine region is fortunate to have over 500,000 acres of land in some type of conservation status (wildlife refuges, state parks, conservancies, etc.), which offers some hope for wildlife preservation in this area.
Sea-Level Rise
Is sea-level rising because of global climate change? Yes. Is human pollution causing it? It is certainly part of the problem. Global temperatures have cycled up and down since the earth formed, and a natural warming has been underway for several thousand years. However, most scientists agree that industrialization has sped the release of gases into the atmosphere that trap heat and are causing a climate change that is warming polar regions (but may also make some regions slightly cooler, and in general make climates everywhere more volatile). This is melting glaciers and adding huge amounts of water to the oceans.
What does sea-level rise mean for the A-P region? The Albemarle-Pamlico Peninsula is highly vulnerable to rising sea level because it is so flat for so many miles inland. Even if the oceans rise just a foot or so by 2100—which most models show is on the low end of what is likely— thousands of acres could be flooded in parts of Hyde, Dare, Tyrrell, and Beaufort counties.
For more information, go to www.pewclimate.org
Key Habitats and Plant Types
Spartina Marsh (Spartina alterniflora)
Spartina alterniflora is the scientific name for salt marsh grass. Spartina marshes are among the earth’s most fertile ecosystems despite living in a harsh, salty environment. Found on the sound side of barrier islands, these marshes have a nutrient-rich soil formed by the continual decomposition of dead Spartina stems. As ocean tides flow back and forth across the marsh, the nutrients are stirred into a feast for zooplankton, fish larvae, and other tiny creatures at the base of the ocean food web. The cycle of plant and animal productivity in a salt marsh rivals rain forests in total biomass (pounds of living matter) per acre.
Baldcypress Trees
Baldcypress trees live in the soggy soils of flooded swamps and river shorelines. They are easily recognized by their broad lower trunk and the “knees” of their root system, which poke out of the ground (or water) all around them. They are called baldcypress because they shed their needles in winter, while all other cypress species are evergreen. Baldcypress trees are the oldest living things in the eastern U.S.—there are some over 1,500 years old in the swamps of southeastern North Carolina, and a few in Florida are believed to be over 3,000 years old. This area’s oldest baldcypresses were logged out between 1750 and 1950, but there are some 200+ year-olds growing in remote swamps.
Lake Mattamuskeet
Lake Mattamuskeet is North Carolina’s largest naturally-formed lake. It is 18 miles wide (east-west) and 6 miles across (north-south), but was about twice that size before settlers began ditching and draining the lake to Pamlico Sound two centuries ago. Despite its size, Mattamuskeet is only 2-3 feet deep in most places.
Unlike most lakes that have a spring or river as a source, Mattamuskeet is just a huge depression in the land filled by rain and runoff. There is some question as to how the depression was formed. One theory suggests an unusual pattern of erosion was responsible. Another says it resulted from a meteorite slamming into the earth. But perhaps the most popular theory is that a fire smoldered for months in underground layers of peat and literally caused the land to sink. Native Americans reputedly told early English settlers of an underground fire that had burned for “13 moons (months)” — an event that is quite possible if a prolonged drought dries out the usually damp peat soil and makes it susceptible to fire through a lightning strike.
Find out about the Mattamuskeet National Wildlife Refuge at www.mattamuskeet.fws.gov
Bottomland Swamps
Bottomland swamps are forests that grow in wet, frequently flooded areas along rivers and lakes. They line many miles of bottomland swamps along the rivers of the A-P region, especially the Roanoke River, where the bottomland spreads inland up to 5 miles in some places. The lowest, wettest parts of bottomlands are usually where cypress and tupelo gums are found (see Baldcypress Trees above). Slightly higher areas are covered with maple, poplar, ash, oak, and other hardwood trees that grow better in drier soils. Bottomlands are vital habitats for many types of birds and mammals, and they store vast amounts of water during floods.
For more information on the Roanoke River bottomlands, go to The Nature Conservancy website at www.nature.org/wherewework and click through to their activities in North Carolina
Pocosins
Most swamps are found in lowlands adjacent to rivers and lakes, but the Albemarle-Pamlico region also is home to an unusual type of swamp called a pocosin (puh-COE-sin). Pocosin is a Native American term that means “high swamp.” It refers to woodlands that are slightly higher than the land around them, but have wet, mucky soils and vegetation typical of bottomlands. They form where underlying layers of clay inhibit the already-slow drainage of this very flat area. Even in an “upland”—which around here can mean an area just a few inches higher than surrounding terrain—the ground can stay wet almost constantly and create a swamp-like environment. The trees and shrubs of a pocosin are generally scrawnier than in a true bottomland, however, because pocosins accrue layers of peat (organic matter that is not completely broken down into more fertile minerals). The Albemarle-Pamlico region has more pocosins than any place in the world—though the habitat is becoming endangered due to clearing and development.
Animals of the A-P Region
The Estuary as Fish Habitat
Over 90% of the commercial seafood species caught by North Carolina fishermen spend at least part of their life in the estuary, and many ocean-going predators depend on those fish for survival. If our sounds, rivers and surrounding habitats are polluted and destroyed, marine life of all types along the Atlantic seaboard will decline.
Different species use the estuary in different ways. Flounder, spot, red drum, gray trout, shrimp, and menhaden are among many fish that hatch in the ocean but live in the estuary as juveniles. Ocean currents carry the newly-hatched fish into the sounds. There the young fry find plenty of plankton to feed on and plenty of shelter from predators in grass beds and marshy shallows. These fish usually return to the ocean as they reach reproductive maturity.
Blue crabs also hatch at sea but live in the estuary. They can be found anywhere from freshwater at the upper edge of the sounds to coastal ocean waters. Females bearing a sponge of fertilized eggs migrate to offshore waters in the fall, where they release their eggs and spend the winter. In spring they return to the estuary, arriving with newly hatched larval crabs that are carried into the sounds on currents. Males bury into the mud bottoms of estuaries during winter and emerge to meet the incoming females as waters warm above 540 (F). Crabs grow by shedding their exoskeleton several times each year; the largest blue crabs are about eight inches across the width of their shell. Blue crabs are North Carolina’s most important commercial species in terms of economic value and number of people employed.
Striped bass, herring, and shad are anadromous fish that have a highly specialized way of using the estuary. They live in Atlantic coastal waters as adults, but in early spring begin migrating in large schools through the sounds and into freshwater rivers to spawn. The young drift down toward the estuary after hatching, and in a year or so join schools of their species in the ocean. When they reach reproductive maturity, anadromous fish return to the waters of their origin to continue a timeless cycle. Seemingly infinite in abundance when Europeans first arrived in America, all of these species have been reduced to marginal population levels by overfishing and loss of spawning habitat. Catch limits and restocking have helped restore striped bass, but herring and shad remain at risk. Even closer to extirpation is the short-nosed sturgeon, another anadromous species of this region that is critically endangered because its slow reproductive cycle cannot overcome generations of loss.
For more information on fisheries of the Albemarle-Pamlico estuary, go to www.ncfisheries.net
Tundra Swans (Olor columbianus)
Tundra swans are the largest of the migrating waterfowl that spend winters in the Albemarle-Pamlico region. In fall, thousands of these majestic birds leave their nesting grounds in northwestern Canada and come to coastal Carolina for its milder climate and sheltered waters. As weather warms in late winter, the swans fly back to Canada to breed a new generation of cygnets (young swans).
Once hunted nearly to extinction, swan populations have rebounded in recent decades thanks to limited hunting seasons and good habitat management. Along with the swans, many types of ducks and geese also come from northern breeding grounds to winter at Lake Mattamuskeet and other area waters.
For more information, go to www.audubon.org, and click on Birds and Science
American Alligators (Alligator mississipiensis)
Though alligators prefer subtropical habitats, some have been making a home in the marshes of the Pamlico Sound and (appropriately) the Alligator River in recent years. No longer considered endangered nationwide, they remain protected in North Carolina because their numbers here are small. While not indigenous to the A-P region, they could become more prevalent if global climate change promotes a northern migration of sub-tropical habitats.
Red Wolves (Canis rufus)
Red wolves were the indigenous wolf of the eastern U.S. prior to European colonization, but were hunted nearly to extinction as settlers pushed westward. The last remaining wild red wolves were captured by the U.S. Fish and Wildlife Service in the 1970s and placed in a captive breeding program. Descendants of those wolves were released on the Alligator River National Wildlife Refuge in 1987, and today there are around 100 wild wolves living on the A-P peninsula. Smaller than their gray wolf cousins, red wolves hunt deer and a variety of smaller animals like rabbits, rodents, and nutria. They are very shy and pose little threat to humans.
For more information, go to www.redwolves.com
Red-cockaded Woodpeckers (Picoides borealis)
The red-cockaded woodpecker (RCW) is a highly endangered species that once thrived in southern woodlands, but was pushed to brink of extinction by widespread forest clearing during the 20th century. Usually found in longleaf pine forests, dozens of RCWs were discovered inhabiting a loblolly/hardwood habitat in Tyrrell County in the 1990s. This land is now a protected area called the Palmetto-Peartree Preserve, which has a hiking trail leading through one of the woodpeckers’ unique nesting colonies. Careful management of habitats like the Palmetto-Peartree Preserve will help ensure the RCWs’ survival.
Other woodpeckers you might see in the A-P region include wren-sized downy and hairy woodpeckers, and the striking pileated woodpecker, which can grow as large as 20” from head to tail.
For more information, go to www.nc-es.fws.gov/birds
Neotropical Migratory Songbirds
Neotropical migratory songbirds are birds that winter in the tropical forests of Central and South America, then migrate to forests of the southeastern U.S. for nesting and breeding in spring. Neotropical songbirds include warblers, tanagers, vireos, hummingbirds, and other birds that are have distinctive calls and are often brightly colored.
These birds need large tracts of wild forest — both here and in the tropics — to sustain healthy populations. We need to protect places like the vast bottomland swamps along the lower Roanoke River in order to keep our world filled with the incomparable color and beauty of neotropicals.
For more information, go to www.audubon.org and click on Birds and Science
Raptors
Raptors are birds of prey like hawks, eagles, owls, and falcons. Raptors are best identified by their sharp claws for seizing prey and hooked beaks that can tear into flesh.
Owls found commonly in this region include great horned owls and barred owls. Indigenous hawks include red-shouldered hawks, Cooper’s hawks, and red-tailed hawks in woodlands, and ospreys (or fish hawks) along waterways. Bald eagles have become increasingly regular sights in recent years, and endangered peregrine falcons are occasionally observed as they migrate through this area. Most raptors prey on rodents, small birds, or snakes and other reptiles. Ospreys and eagles feed mainly on fish. Turkey vultures are also considered raptors, but they feed exclusively on carrion (dead animals) and do not hunt live prey.
For more information, go to www.audubon.org and click on Birds and Science
For More Information
If you would like more information about plants, animals, habitats, environmental issues, or other topics related to the Albemarle-Pamlico sounds, please email your question to estuarium@embarqmail.com, and put Soundbites in the subject line.