Coastal ecology is shaped by the close relationship between people, wetlands, estuaries, and open water. In the United States, coastal counties support large populations and economies while coastal wetlands provide habitat and help reduce storm damage. The statistics below describe that relationship using national, regional, and watershed measurements from NOAA, the EPA, and the U.S. Fish and Wildlife Service.
Contents
- People and economic activity
- The national coastal wetland footprint
- Wetland condition in the Coastal Plains
- Wetland change in coastal watersheds
- Regional and habitat patterns
- Estuaries, wildlife, and restoration
- Protection, damage reduction, and pressure
People and economic activity
Coastal ecology matters in places where population, employment, commerce, and habitat occupy the same limited geography. NOAA Economics and Demographics reports that U.S. coastal counties are home to 129 million people, almost 40 percent of the nation’s population. Those counties account for less than 10 percent of the nation’s land mass when Alaska is excluded. Between 1970 and 2020, their population increased by 40.5 million people, or about 46 percent.
The population is concentrated. California has 26.8 million people living in coastal counties, followed by Florida with 16.2 million, New York with 15.9 million, New Jersey with 7.2 million, and Texas with 6.9 million. Coastal counties average about 468 people per square mile excluding Alaska, compared with roughly 113 people per square mile for the U.S. average on the same basis.
NOAA Economics and Demographics also reports that coastal counties produce $10 trillion in goods and services annually, employ 54.6 million people annually, and pay $4 trillion in wages annually. These figures describe the scale of human activity surrounding coastal ecosystems; they are not measures of ecological health.
Social conditions are uneven within that population. Nearly 22 percent of people in coastal shoreline counties have at least three components of social vulnerability, according to NOAA Economics and Demographics. That statistic is important when ecological change, flooding, or storm damage is considered alongside habitat and water-quality measurements.
The national coastal wetland footprint
NOAA’s official total U.S. shoreline length is 153,646 kilometers, or 95,471 miles. Coastal wetlands cover about 40 million acres, according to EPA About Coastal Wetlands, and make up 38 percent of total wetland acreage in the conterminous United States. The Southeast contains 81 percent of conterminous U.S. coastal wetlands, making that region especially important in national coastal ecology statistics.
The national footprint is under continuing pressure. EPA About Coastal Wetlands reports that coastal wetlands in the eastern United States were lost at about 80,000 acres per year between 2004 and 2009. The earlier 1998-to-2004 study found losses of about 59,000 acres per year. A broader summary states that more than 80,000 acres of coastal wetlands are lost on average each year in the United States.
NOAA Fisheries Value of Coastal Wetland Habitat similarly says nearly 80,000 acres of coastal wetlands are lost in the United States each year to development, draining, erosion, and sinkage. Since 2008, NOAA Fisheries and partners have restored nearly 50,000 acres of wetland habitat. The loss and restoration figures cover different processes and periods, so they should not be treated as a single net-change calculation.
Coastal waters also support breeding habitat for 85 percent of U.S. migratory birds, according to EPA Coastal Waters. That percentage connects shoreline and wetland condition to species that may use coastal habitats during a part of their life cycle.
Wetland condition in the Coastal Plains
The National Wetland Condition Assessment estimates 37,036,517 acres of wetlands in the Coastal Plains ecoregion. EPA Coastal Plains Ecoregion NWCA reports condition ratings for several indicators across that wetland area.
| Coastal Plains indicator | Area rated good | Area rated poor |
|---|---|---|
| Vegetation | 56% | — |
| Nonnative plants | 67% | — |
| Cumulative physical alterations | — | 31% |
| Vegetation replacement | — | 22% |
| Nitrogen | — | 23% |
| Phosphorus | — | 28% |
The same EPA assessment reports that nitrogen and phosphorus indicators could not be assessed for 28 percent of wetland area. That limitation matters because a percentage rated poor does not describe the entire assessment area when some sites lack an assessment for a given indicator.
Condition also changed between assessment periods. From 2016 to 2021, the share of wetland area rated good for vegetation in the Coastal Plains ecoregion fell by 2 percentage points. Over the same period, the share rated good for nonnative plants fell by 6 percentage points. These are changes in the assessment ratings, not acreage losses.
Wetland change in coastal watersheds
The U.S. Fish and Wildlife Service 2009 to 2019 report found that coastal watersheds lost 191,000 acres of wetland area overall. Net freshwater wetland loss was 160,000 acres. The South Atlantic and Gulf of Mexico coastal watersheds sustained the largest combined wetland losses at 114,000 acres. Within that reporting, South Atlantic coastal watersheds lost 77,500 acres, while Great Lakes coastal watersheds lost 32,600 acres.
Not every region lost wetland area. North Atlantic coastal watersheds gained 19,883 acres between 2009 and 2019, and Pacific coastal watersheds gained 12,700 acres. These regional results show why a national total can conceal different directions of change across coastal settings.
The report identifies several types of transition. Conversion to upland caused a 136,000-acre wetland reduction in coastal watersheds, while conversion to deepwater caused a 55,000-acre reduction. Vegetated wetlands declined by 314,000 acres, non-vegetated wetlands increased by 133,000 acres, and deepwater categories increased by 87,000 acres.
The reported rate of wetland loss within coastal watersheds was 18,000 acres per year from 2009 to 2019. The previous coastal wetland loss rate was 80,000 acres per year from 2004 to 2009. Because these rates refer to different study periods and reporting scopes, the later figure should not be used as a simple continuation of the earlier one.
Regional and habitat patterns
Saltwater habitats show distinct changes within the 2009-to-2019 coastal-watershed assessment. Saltwater vegetated wetlands decreased by 1.3 percent, or 68,000 acres. Estuarine emergent marsh declined by 1.8 percent, or 74,000 acres. Conversion of salt marsh to marine and estuarine subtidal deepwater accounted for 65,000 acres, and conversion of salt marsh to intertidal non-vegetated wetlands accounted for 23,000 acres.
Freshwater categories also contributed to change. Freshwater wetland loss to upland urban areas totaled 42,000 acres between 2009 and 2019. Loss to upland other categories totaled 32,000 acres, loss to upland rural development totaled 6,000 acres, and loss to upland forested plantations totaled 61,000 acres. Freshwater wetland loss to lacustrine deepwater totaled 9,000 acres.
The earlier U.S. Fish and Wildlife Service 1998 to 2004 report estimated 39.8 million acres of wetlands in U.S. coastal watersheds in the eastern U.S. study. That represented 38 percent of conterminous U.S. wetland acreage. Freshwater wetlands made up 34.0 million acres, or 86 percent, while saltwater wetlands made up 5.8 million acres, or 14 percent.
Within the saltwater total in that study, estuarine emergent wetlands were 4.1 million acres, or 71 percent, of all estuarine and marine wetlands. Freshwater composition included forested wetlands at 62 percent of freshwater wetland area, shrub wetlands at 19 percent, emergent wetlands at 16 percent, and freshwater ponds at 3 percent.
Estuaries, wildlife, and restoration
The Chesapeake Bay watershed covers 64,000 square miles, or 165,759 square kilometers, and includes more than 150 rivers and streams, according to NOAA Chesapeake Bay fact. More than 17 million people live in the watershed, and more than 83,000 farms generate more than $10 billion annually.
The watershed supports more than 300 species of fish, shellfish, and crab, while more than 250 fish species use the Chesapeake Bay and tributaries for some portion of their life cycles. More than 300 migratory bird species can be found there, and about one million ducks, geese, and swans return to overwinter on the Chesapeake each fall.
NOAA Estuary Habitat reports that polluted runoff causes a dead zone in the Gulf of America each year spreading over more than 6,000 square miles. NOAA’s National Estuarine Research Reserve program currently protects more than 1.3 million acres of coastal wetland. NOAA and partners built or enhanced almost 3,000 acres of habitat in Louisiana’s Barataria Bay.
Restoration can also have measurable property effects. A $3.5 million NOAA-supported wetland restoration project in California increased residential property values by $36.3 million, according to NOAA Estuary Habitat. The statistic describes that project and should not be generalized to every restoration site.
Protection, damage reduction, and pressure
Wetlands can reduce storm-related property damage. Areas behind existing salt marshes have 20 percent fewer property damages, according to NOAA coastal fast facts. The Nature Conservancy says coastal wetlands prevented more than $625 million in property damages during Hurricane Sandy. In New Jersey, wetlands saved more than $425 million in property damages during that storm, while in Maryland wetlands reduced damages by 29 percent.
Long Island Sound has lost 50 percent of its wetlands in the past 130 years, according to NOAA coastal fast facts. That long historical period differs from the shorter monitoring windows in the coastal-watershed studies, so the figures describe different kinds of change.
Coastal communities also face broader climate and economic pressures. NOAA coastal fast facts records 15 U.S. weather and climate disasters in 2016 with losses exceeding $1 billion. Among 203 weather disasters from 1980 to 2016, tropical cyclones caused $560.1 billion in total damage, averaged $16 billion per event, and caused 3,210 deaths.
Marine transportation and seafood add another dimension. Seventy-six percent of all trade involves some form of marine transportation, while 90 percent of international trade involves marine transportation, according to NOAA coastal fast facts. Nearly 1.4 million jobs were supported by the seafood industry in 2014, with $153 billion in sales impacts. Americans consumed more than 4.6 billion pounds of seafood in 2013, equal to about 14.5 pounds per person.
Since 2006, NOAA has supported over 100 marine debris removal projects that removed more than 5,500 metric tons of debris from the oceans. Worldwide, more than 200 species of marine life have been negatively impacted by debris. Together, these measurements show how coastal ecology is linked to habitat, hazards, commerce, food systems, and the condition of waters used by people and wildlife.