Status and trends of wetlands in the coastal watersheds of the eastern United States 1998 to 2004

              Status and Trends
of Wetlands
IN THE Coastal Watersheds of the Eastern United States
1998 to 2004
Conversion Table
United States Customary to Metric
United States Units Metric Units
inches (in.) x 25.40 millimeters (mm)
inches (in.) x 2.54 centimeters (cm)
feet (ft) x 0.30 meters (m)
miles (mi) x 1.61 kilometers (km)
nautical miles (nmi) x 1.85 kilometers (km)
square feet (ft²) x 0.09 square meters (m²)
square miles (mi²) x 2.59 square kilometers (km²)
acres (A) x 0.40 hectares (ha)
Farenheit degrees (F) 0.5556 (F - 32) Celsius degrees (C)
Metric to United States Customary
Metric Units United States Units
millimeters (mm) x 0.04 inches (in.)
centimeters (cm) x 0.39 inches (in.)
meters (m) x 3.28 feet (ft)
kilometers (km) x 0.62 miles (mi)
kilometers (km) x 0.54 nautical miles (nmi)
square meters (m²) x 10.76 square feet (ft²)
square kilometers (km²) x 0.39 square miles (mi²)
hectares (ha) x 2.47 acres (A)
Celsius degrees (C) 1.8(C) + 32 Farenheit degrees (F)
S t a t u s a n d T r e n d s o f W e t l a n d s 1
National Oceanic and Atmospheric Administration
National Marine Fisheries Service
and
U.S. Department of the Interior
Fish and Wildlife Service
Status and Trends
of Wetlands
IN THE Coastal Watersheds of the Eastern United States
1998 to 2004
This report should be cited as:
Stedman, S. and T.E. Dahl. 2008. Status and trends of wetlands in the coastal watersheds of the Eastern United States 1998
to 2004. National Oceanic and Atmospheric Administration, National Marine Fisheries Service and U.S. Department of the
Interior, Fish and Wildlife Service. (32 pages)
General Disclaimer
The use of trade, product, industry, or firm names or products in this report is for informative
purposes only and does not constitute an endorsement by any agency of the U.S. Government.
Status and Trends of Wetlands
Coastal Watersheds of the Eastern United States
1998 to 2004
Susan-Marie Stedman
NOAA, National Marine Fisheries Service
and
Thomas E. Dahl
U.S. Fish and Wildlife Service
Acknowledgments
The authors wish to thank numerous agencies and individuals who provided input to this report. Particularly helpful
were interagency briefings sponsored by the National Oceanic and Atmospheric Administration’s (NOAA) National Marine
Fisheries Service (NMFS) and the U.S. Environmental Protection Agency (EPA), Office of Wetlands, Oceans, and Watersheds,
and attended by senior staff from the Council on Environmental Quality, Office of Management and Budget, U.S. Army Corps
of Engineers, U.S. Department of Agriculture, NOAA, EPA, and U.S. Fish and Wildlife Service (FWS). These briefings helped
formulate the context and presentation of the report findings and set the stage for additional collaborative efforts.
In addition, expert subject matter peer review was provided by the following technical specialists: Michael Scozzafava,
Wetlands Division, EPA; William B. Ainslie, Wetlands Regulatory Section, EPA Region IV; Jennifer A. Wheeler, Waterbird
Coordinator, Division of Migratory Bird Management, FWS; Martin Kodis, Chief, Branch of Resource and Mapping Support,
Division of Habitat and Resource Conservation, FWS; FWS Regional Wetlands Coordinators Bill Kirchner, Brian Huberty, John
Swords, Ralph Tiner, Kevin Bon, and Jerry Tande; Gary Whelan, Michigan Department of Natural Resources; and Tom Bigford,
NMFS Office of Habitat Conservation.
S t a t u s a n d T r e n d s o f W e t l a n d s 3
CONTENTS
Executive Summary 5
Introduction 6
Coastal Wetlands 7
Current Study Area, Procedures, and Objectives 10
Definitions of Habitat Categories within Coastal Watersheds 12
Results: Status, Distribution, and Trends 14
Summary and Conclusions 26
References Cited 27
Appendix: Definitions of Habitat Categories 29
4 S t a t u s a n d T r e n d s o f W e t l a n d s
List of Figures
Figure 1. Coastal watersheds of the Atlantic, Gulf of Mexico, and Great Lakes 10
Figure 2. Wetland area of the coastal watersheds of the Atlantic, Gulf of Mexico,
and Great Lakes 14
Figure 3. Wetland types in the coastal watersheds of the Atlantic, Gulf of Mexico,
and Great Lakes, 2004 14
Figure 4. Wetland density in the coastal watersheds of the Atlantic and
Gulf of Mexico, 2004 15
Figure 5. Wetland gains and losses for the Atlantic, Gulf of Mexico, and
Great Lakes coastal watersheds, 1998 to 2004 17
Figure 6. Attribution of loss or conversion of saltwater wetlands in the
coastal watersheds of the Atlantic and Gulf of Mexico, 1998 to 2004 20
Figure 7. Areas of greatest coastal wetland loss in the Gulf of Mexico 24
Figure 8. Attribution of loss or conversion of freshwater wetlands in the coastal
watersheds of the Atlantic, Gulf of Mexico, and Great Lakes, 1998 to 2004 24
Figure 9. Net gains and losses of coastal wetlands in the Great Lakes
coastal watersheds, 1998 to 2004 24
Figure 10. St. Vincent Island restoration site, Florida, post-restoration 25
List of Tables
Table 1. Previous studies of coastal wetland status and trends 8
Table 2. Area of coastal watersheds in this study 11
Table 3. Wetland, deepwater, and upland categories used in this study 13
Table 4. Estimated change in wetland area for selected wetland categories
for coastal watersheds of the Atlantic, Gulf of Mexico, and Great Lakes,
1998 to 2004 16
Table 5. Estimated changes to saltwater (estuarine and marine) wetlands
in the coastal watersheds of the Atlantic and Gulf of Mexico coasts,
1998 to 2004 19
Table 6. Estimated freshwater wetland acreage for coastal watersheds
of the Atlantic, Gulf of Mexico, and Great Lakes as compared to the
conterminous United States, 2004 21
Table 7. Estimated changes to freshwater wetlands in the Coastal Watersheds
of the Atlantic, Gulf of Mexico, and Great Lakes, 1998 to 2004 22
S t a t u s a n d T r e n d s o f W e t l a n d s 5
EXECUTIVE SUMMARY
he National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, in
cooperation with the U.S. Fish and Wildlife Service, analyzed the status and recent trends of
wetland acreage in the coastal watersheds of the United States adjacent to the Atlantic Ocean,
Gulf of Mexico, and Great Lakes. Sample plots were analyzed using digital high-resolution
imagery to identify wetlands and land use changes observed between 1998 and 2004. T
Results indicate that there were an estimated 39.8
million acres (16.1 million ha) of wetlands in these
coastal watersheds in 2004. This represented 38
percent of the estimated total wetland acreage of
107.7 million acres (43.6 million ha) found in the
conterminous United States.
Coastal watersheds experienced a net loss in wetland
area. There was an estimated wetland loss of 361,000
acres (146,200 ha) in the coastal watersheds of the
eastern U.S. between 1998 and 2004. This equated
to an average annual net loss of about 59,000 acres
(24,300 ha) over the 6-year period of this study. Gulf
of Mexico coastal watersheds exhibited substantial
losses in freshwater wetlands. This rate of loss was
6 times higher than the rate of freshwater vegetated
wetlands losses in the Atlantic coastal watersheds. The
estimated losses for all wetland types in the Gulf of
Mexico were 25 times higher than those estimates for
the Atlantic over the course of this study. There was
a net gain of an estimated 24,650 acres (10,000 ha)
in the Great Lakes coastal watersheds over the same
period of time.
In the time period encompassed by this study, trends
suggested the country as a whole was gaining wetlands.
From 1998 to 2004, wetland gains in the conterminous
United States were estimated to have been 32,000
acres (12,960 ha) annually. The fact that coastal
watersheds were losing wetlands despite the national
trend of net gains points to the need for more research
on the natural and human forces behind these trends
and to an expanded effort on conservation of wetlands
in these coastal areas. This point was highlighted in a
2008 report on wetland conservation by the Council on
Environmental Quality.
6 S t a t u s a n d T r e n d s o f W e t l a n d s
INTRODUCTION
his report is the result of a cooperative effort between the National Oceanic and Atmospheric
Administration’s (NOAA) National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife
Service (FWS). The efforts to monitor coastal wetland status and trends described in this report
have been enhanced by the multi-agency involvement in the study’s design, data collection,
verification, and peer review of the findings. T
NMFS’ mission is to conserve, protect, and manage living
marine resources in a way that ensures their continuation
as functioning components of marine ecosystems, affords
economic opportunities, and enhances the quality of
life for the American public. Coastal wetlands provide
valuable habitat for the vast majority of commercially
harvested and recreational marine species. NOAA has
produced regional and localized studies tracking land use
and wetland change in coastal areas, as well as studies
on the ecological and economic importance of coastal
wetlands (NOAA 2005, 2008). The NMFS Habitat Program
places special emphasis on the conservation of wetlands
as essential fish habitat for harvested species and vital
habitat for other species of ecological significance.
The mission of FWS is to conserve, protect, and enhance
fish and wildlife and their habitats for the continuing
benefit of the American people. The importance of
wetlands as fish and wildlife habitat has always been
the primary focus of FWS’ wetland activities. FWS
communicates information essential for public awareness
and understanding of the importance of fish and wildlife
resources and changes in environmental conditions that
can affect the welfare of Americans. To this end, FWS
maintains an active role in monitoring wetland habitats
of the nation. NMFS and FWS have collaborated in a
number of efforts that produce information on coastal
habitats for fish and wildlife species. NOAA provided
financial and logistical support for the previous two
iterations of the Wetland Status and Trends report
published in 2001 and 2006.
Because wetlands are often viewed as transitional
habitats between water and dry land, wetland abundance,
type, and quality are directly reflected in the health and
abundance of many fish and wildlife species. Coastal
wetland ecosystems include the wetlands immediately
along the sea coast or Great Lakes and along the rivers
and bays that make up the coastal drainage area. Coastal
wetlands support life on land and in the sea by providing
nutrients, food, and places for plants and animals to
reproduce and grow.
The Emergency Wetlands Resources Act of 1986 (Public
Law 99-645) was enacted to promote the conservation
of our nation’s wetlands. The Act requires FWS to
conduct wetland status and trend studies of the nation’s
wetlands at periodic intervals. This is accomplished using
a stratified, random sampling design where sample plots
are examined with the use of remotely sensed imagery,
in combination with field work, to determine wetland
change.
The most recent national study detailed the status and
trends of wetlands from 1998 to 2004 (Dahl 2006).
Wetland trends data collected as part of that effort also
provided statistical estimates of wetland status and
trends for the coastal watersheds contained in this report.
This report analyzed 2,265 sample plots using digital
high-resolution imagery to identify wetlands, deepwater
habitats, and uplands. Changes in areal extent or type of
wetland observed in the sample plots between 1998 and
2004 were recorded. Field verification was completed for
824 of the sample plots (36 percent).
This report presents the latest status information on
coastal wetland resources and provides estimates of losses
or gains that occurred in the coastal watersheds between
1998 and 2004. These data were analyzed beyond the
national data set and provide new information about
wetland trends specific to the coastal watersheds of the
Atlantic, Gulf of Mexico, and Great Lakes coasts It should
be noted that the estimates of wetland area were made
prior to hurricanes Katrina and Rita in 2005.
S t a t u s a n d T r e n d s o f W e t l a n d s 7
Coastal Wetlands
Coastal wetlands occur along the shores of the United States, with the largest expanses along the
Gulf of Mexico and southern Atlantic coasts. Coastal wetland ecosystems are integrated by the
water that flows through them, which connects the wetlands immediately along the ocean or Great
Lakes with those of the rivers and floodplains upstream. Coastal wetland types are as diverse as salt
marshes, bottomland hardwood swamps, fresh marshes, mangrove swamps, and shrub depressions
known in the southeast United States as “pocosins.” The definitive factor in coastal wetlands is
the effect of tides on the watershed as a whole. For this reason, coastal wetlands can be described as all wetlands
below head of tide in watersheds that drain to the Atlantic Ocean, Gulf of Mexico, or Pacific Ocean, as well as
wetlands that drain directly to one of the Great Lakes. The target population of wetlands included in this study was
all wetlands in the coastal watersheds of the Atlantic, Gulf of Mexico, and Great Lakes.1
Coastal wetlands, like inland wetlands, are among the
most productive ecosystems on Earth. The bidirectional
water movement caused by tides in marine coastal
wetlands can augment productivity to even higher
levels in what is called a “tidal subsidy.” The close
connection between coastal wetlands and large water
bodies provides extensive coastal transport mechanisms
driven by littoral drift and larger ocean currents such
as the Gulf Stream, and the large interlake circulation
cells exhibited by each of the Great Lakes can magnify
the role coastal wetlands play on marine ecosystems.
More than half of commercially harvested fish in the
United States depend on estuaries and nearby coastal
waters at some stage in their life cycle (Lellis-Dibble et
al. 2008). Coastal habitats provide spawning grounds,
nurseries, shelter, and food for finfish, shellfish, birds,
and other wildlife (NRC 1997). The abundance and
health of adult stocks of commercially harvested
shrimp, blue crabs, oysters, and other species are
directly related to wetland quality and quantity (Turner
and Boesch 1988; Stedman and Hanson 2000). The
nation’s coastal resources also provide resting, feeding,
and breeding habitat for 85 percent of waterfowl and
other migratory birds (EPA 2005), and nearly 45 percent
of the nation’s endangered and threatened species are
dependent on coastal habitats (FWS 1995). Wetlands
help improve surface water quality by filtering, storing,
and detoxifying residential, agricultural, and urban
wastes, and can buffer coastal areas against storm
and wave damage and help stabilize shorelines. The
economic value of coastal habitats is likely to be in the
hundreds of billions of dollars, if not more (Pendleton
2008).
Because of their close proximity to terrestrial systems,
coastal wetlands are vulnerable to land development,
pollutant discharges, and other human activities.
Coastal wetland losses and degradation can be directly
traced to population pressures and other human-induced
changes occurring along the coast. Expanding
populations place pressures on existing natural
resources, particularly wetlands, which are vulnerable
to changes in water flow, pollution, and habitat
fragmentation. Human populations in coastal areas
have increased steadily since 1970 (U.S. Commission on
Ocean Policy 2004). Currently over half the population
of the United States lives in coastal counties at
densities about five times greater than those of non-coastal
counties (Crossett et al. 2004). This trend of
people moving to coastal areas is expected to continue
in the coming decades.
The results of previous studies of coastal wetland status
and trends are summarized in Table 1. Understanding
the status and trends of coastal wetlands is complicated,
in part, by the lack of a universally accepted definition
C
1 This study did not include the Pacific coast due to insufficient data.
8 S t a t u s a n d T r e n d s o f W e t l a n d s
of “coastal” in past studies. NOAA produced two
estimates of coastal wetlands: one used state data for
wetlands in coastal counties in the Atlantic, Pacific,
and Gulf of Mexico coasts (Alexander et al. 1986), and
the other used a statistical sampling of the existing
FWS National Wetlands Inventory maps for wetlands
in coastal counties and watersheds along the Atlantic,
Pacific, and Gulf of Mexico coasts (Field et al. 1991).
The two estimates of wetland area generated by these
studies differed substantially, although the relative
abundance of wetlands along the Gulf of Mexico and
relatively small amount of wetlands on the Pacific coast
were consistent between the two studies. The study by
Field et al. (1991) estimated that about a third of the
country’s wetlands were coastal.
Table 1. Previous Studies of Coastal Wetland Status and Trends
(Atlantic, Pacific, and Gulf of Mexico only)
Study Coastal Definition Year
Area Estimate
(acres) Time Period
Loss Estimate
(acres/year)
Gosselink and
Bauman 1980
non-fresh tidal wetlands
in coastal counties
1922 9,980,000
1954 9,330,000 1922 - 1954 20,000
1974 8,405,000 1954 – 1974 46,000
Alexander et al.
1986
wetlands in coastal counties 1970s 11,000,000 NA
Tiner 1991 estuarine wetlands (excluding
the Pacific coast)
1970s 5,532,000 1974-1983 7,900
Field et al. 1991 wetlands in coastal watersheds 1980s 27,000,000 NA
Brady and
Flather 1994
tidal wetlands on
non-federal lands
1982 6,713,460 1982-1987 19,323
1987 6,617,380
Brady and
Goebel 2002
wetlands in coastal counties
on non-federal lands
1992 22,430,000 1992-1997 24,400
1997 22,300,000
In 1994, scientists with the U.S. Department of
Agriculture’s (USDA) Natural Resources Conservation
Service reviewed the USDA’s Natural Resources
Inventory (NRI) data for 1982 to 1987 and separated it
into “coastal” and “inland” using the definitions in the
FWS’ original wetland classification system known as
“Circular 39” (Brady and Flather 1994). They updated
the work in 2002 (Brady and Goebel 2002) for the 1992
to 1997 data, including all wetlands in coastal counties
as coastal wetlands. Like the NOAA estimates, this
included only the Atlantic, Pacific, and Gulf of Mexico
coasts of the coterminous United States. The 2002
results are close to those of the second NOAA inventory
in that approximately a third of the wetlands in the
coterminous United States were found to be “coastal,”
with the majority of them in the freshwater system.
Again, lack of consistency in defining the term and
geographical extent of “coastal” has hampered
interpretation of the above studies. Dahl (2006)
pointed out that geographic dissimilarity, differences in
terminology, and different time periods accounted for
discrepancies in wetland loss estimates in Louisiana.
Gosselink and Baumann (1980) compiled information
from the USDA’s swamplands survey of 1922, the first
National Wetlands Inventory in 1954 (Shaw and Fredine
S t a t u s a n d T r e n d s o f W e t l a n d s 9
1956), and state surveys made in the early 1970s for
the Atlantic, Pacific, and Gulf of Mexico coasts of the
coterminous United States. They calculated two coastal
wetland loss rates: 19,000 acres per year for 1922–1954
and 46,000 acres per year for 1954–1974. The two
studies using NRI data yielded estimates of 19,000 acres
per year for 1982–1987 and 32,600 acres per year for
1992–1997. However, it is important to remember that
none of these studies, not even the two using NRI data,
used consistent methodologies, so these rates are not
comparable and can be used only as estimates of the
order of magnitude of coastal wetland loss during those
periods.
Brady and Goebel (2002) drew some interesting
conclusions from the 1992–1997 data analysis. They
stated that coastal counties (excluding the Great Lakes)
occupy 7 percent of the land area, have 20 percent of
the wetlands, and 31 percent of the gross wetland loss
(on non-federal, rural lands). They also found that
42 percent of the loss of wetlands to development
occurred in coastal counties, and that wetland gains in
inland counties nearly offset losses, whereas the area
of wetlands lost in coastal counties was more than
four times the area of wetlands gained.2 These results
pointed to the need for a more in-depth and consistent
approach to understand the current status and trends
of coastal wetlands.
2 This study made no attempt to determine the quality of wetlands that were lost or gained.
10 S t a t u s a n d T r e n d s o f W e t l a n d s
Current Study Area,
Procedures, and Objectives
nalysis of the FWS’ national wetlands status and trends dataset was conducted to provide
information specifically on the status and extent of wetland resources in the coastal
watersheds of the Atlantic, Gulf of Mexico, and Great Lakes (Figure 1). The most recent
national study detailed the status and trends of wetlands from 1998 to 2004 (Dahl 2006).
In that study, 4,682 randomly selected plots were assessed using digital high-resolution
imagery to identify change in wetlands, deepwater habitats, and uplands. Each sample
plot was 4.0 square miles total area (2,560 acres). For each plot, digital aerial imagery was acquired and interpreted
to identify wetlands, deepwater habitats, and uplands and the changes in areal extent or type of wetland observed
in the sample plots between 1998 and 2004. This report presents additional information specific to the coastal
watersheds areas of the Atlantic, Gulf or Mexico, and Great Lakes coasts. Findings were based on 2,265 sample
plots that fell within the coastal watershed study area.
The United States has been divided and
subdivided into successively smaller hydrologic
units, which have been classified into four
levels by the U.S. Geological Survey (Seaber et
al. 1994).
Since approximately 1990, NOAA has used
a specific methodology to identify coastal
watersheds. The methodology combined
information on the extent of tidal influence
(head of tide) and the U.S. Geological Survey’s
mapping of watersheds, identifying those
8-digit hydrologic unit watersheds that
contained tidal water bodies. A similar method
was used for Great Lakes wetlands using direct
drainage to the Great Lakes instead of tidal
effects. Because of the varying and complex
state and federal laws governing the placement
of coastal boundaries, closure of the hydrologic
units was not provided by the Hydrologic Unit
Maps along the coastline of the United States
(Seaber et al. 1994). In this study, the outer
coastal boundary was determined by the
extent of the coastal sampling frame used by
the FWS’ National Wetlands Status and Trends Study for the Atlantic, Gulf of Mexico, and Great Lakes coastal areas.
The inland study boundary coincided with the corresponding coastal watershed. The total area sampled in these
three areas was 212.6 million acres3 (Table 2).
A
Figure 1. Coastal watersheds of the Atlantic, Gulf of Mexico, and Great Lakes.
S t a t u s a n d T r e n d s o f W e t l a n d s 11
Table 2. Area (in acres) of
Coastal Watersheds in this Study.
Coastal Watershed Area (acres)
Atlantic 89,061,946
Gulf of Mexico 67,556,077
Great Lakes 55,936,677
Total Study Area 212,554,700
Wetland changes were determined by intensive analysis
of the aerial imagery, interpretation of wetland types
and hydrologic conditions, and determination of the
changes that occurred between the respective target
dates. The mean dates of the aerial imagery used to
determine wetland trends were 1998 and 2004, with
the difference being an average of 6 years. For this
study, wetlands 1.0 acres and larger composed the
target population.4 Actual results indicated that for
each wetland category included in the study, the
minimum size represented was less than 1.0 acre.
Additional information on the study design, data
collection, and analysis procedures has been discussed
by Dahl (2006).
3 This study incorporated some estuarine embayments not included in the total land area figure.
4 Smaller wetlands were detected and included in the study, but it cannot be determined that all wetlands less than 1.0 acre were
detected.
Changes were recorded in areal extent or type of
wetland observed on the sample plots between 1998
and 2004. Field verification of features on the aerial
imagery was done for 824 plots (36 percent) during
2004 and 2005. Field verification addressed questions
regarding image interpretation, land use coding, and
attribution of wetland gains or losses. Field work
was also performed as a quality control measure to
verify that plot delineations were correct. Verification
involved field visits to a variety of wetland types and
geographical settings.
To reflect reliability, each estimate is accompanied by
a percent coefficient variation expressed as a percent
(i.e., there is a 95 percent probability that an estimate
was within the indicated percentage range of the
true value). The wetland area estimates generated
for this study include all wetlands regardless of land
ownership.
12 S t a t u s a n d T r e n d s o f W e t l a n d s
Study Limitations
Due to the limitations of using aerial imagery as
the primary data source to detect wetlands, certain
habitats were excluded from this study by design.
These included:
Reefs — Tropical reef communities (coral or tuberficid
worm reefs) occurred offshore in south Florida waters.
These reefs ranged in water depth from less than 1 m
to 41 m. Coral reefs were concentrated complexes
of corals and other organisms that constructed a
limestone structure in shallow waters (Jaap 1984).
Reefs provided important links to fishery and benthic
Wetlands
T his study used the Fish and Wildlife Service definition of wetland (Cowardin et al. 1979). This definition
is the national standard for wetland mapping, monitoring and data reporting as determined by the
Federal Geographic Data Committee (2005). It is a two-part definition as indicated below:
Wetlands are lands transitional between terrestrial and aquatic systems where the water table is
usually at or near the surface or the land is covered by shallow water.
For purposes of this classification wetlands must have one or more of the following three
attributes: (1) at least periodically, the land supports predominantly hydrophytes, (2) the substrate
is predominantly undrained hydric soil, and (3) the substrate is nonsoil and is saturated with water
or covered by shallow water at some time during the growing season of each year.
Habitat category definitions are given in synoptic form in Table 3. The reader is encouraged to also review the
Appendix, which provides complete definitions of wetland types and land use categories used in this study.
Deepwater Habitats
Cowardin et al. (1979) consider wetlands and deepwater
habitats separately; that is, the term wetland does not
include deep, permanent water bodies. Deepwater
habitats are permanently flooded land lying below
the deepwater boundary of wetlands. Deepwater
habitats include environments where surface water is
permanent and often deep, so that water, rather than
air, is the principal medium in which the dominant
organisms live, whether or not they are attached to
the substrate. In lacustrine and riverine systems, the
boundary between deepwater and wetland habitats is
approximately 2m (6.6 ft) below low water, or at the
deepest extent of emergents, shrubs, or trees. For
the purposes of this study, all lacustrine (lake) and
riverine (river) waters without visible vegetation were
considered deepwater habitats.
Upland Habitats
An abbreviated upland classification system patterned
after the U. S. Geological Survey land classification
scheme described by Anderson et al. (1976), with five
generalized categories, was used to describe uplands in
this study. These categories are also listed in Table 3.
Definitions of Habitat Categories
within Coastal Watersheds
S t a t u s a n d T r e n d s o f W e t l a n d s 13
Table 3. Wetland, deepwater, and upland categories used in this study.
The definitions for each category appear in the Appendix.
Salt Water Habitats Common Description
Marine Subtidal* Open Ocean
Marine Intertidal Near shore
Estuarine Subtidal* Open-water/bay bottoms
Estuarine Intertidal Emergents Salt marsh
Estuarine Intertidal Forested/Shrub Mangroves or other estuarine shrubs
Estuarine Intertidal Unconsolidated Shore Beaches/bars/shoals
Riverine* (may be tidal or non-tidal) River systems/channels
Freshwater Habitats
Palustrine Forested Forested wetlands
Palustrine Shrub Shrub wetlands
Palustrine Emergents Inland marshes/emergent wetlands
Palustrine Unconsolidated Shore Shorelines/beaches/bars
Palustrine Unconsolidated Bottom Open-water ponds
Palustrine farmed Farmed wetland
Lacustrine* Deepwater lakes and reservoirs
Uplands
Agriculture Cropland, pasture, managed rangeland
Urban Cities and incorporated developments
Forested Plantations Planted or intensively managed forests; silviculture
Rural Development Non-urban developed areas and Infrastructure
Other Uplands Rural uplands not in any other category; barren lands
*Constitutes deepwater habitat
marine resources and along with seagrasses and
mangroves formed vital components of the coastal
ecosystem (Miller and Crosby 1998). The only
emergent coral reefs found in the conterminous U.S.
were located in the Florida Keys extending south from
Miami and Soldier Key to the Dry Tortugas. Coral reef
extent and changes were not quantified as part of this
study. Although data from other studies were available
for only limited geographical sites, there has been
widespread agreement that coral reef area has been
declining (Millhouser et al. 1998).
Oyster (Crassostrea virginica) reefs also occurred in
the intertidal zone adjacent to marshes or mud flats of
mid and south Atlantic states and along the Gulf coast.
There were also a number of artificially created reefs in
coastal waters. The area of oyster reefs and artificial
reefs were also not quantified in this study.
Seagrases or Submerged Aquatic Vegetation
— Detection of submerged aquatic vegetation required
specialized techniques such as those described by
Dierssen et al. (2003) to accurately determine the
extent of seagrasses. Seagrasses and other submerged
plants inhabited the intertidal and subtidal zones of
estuaries and near shore coastal waters (Orth et al.
1990). Seagrasses have been used to characterize
water quality because of their widespread distribution,
important ecological niche and their sensitivity to water
quality changes. The data presented in this report do
not include area estimates of seagrasses or submerged
aquatic vegetation.
Ephemeral Water — Cowardin et al. (1979) did not
recognize ephemeral water areas as a wetland type
and ephemeral waters were not included in this study.
This is consistent with other national Wetlands Status
and Trends studies conducted by the Fish and Wildlife
Service (Dahl 2006).
14 S t a t u s a n d T r e n d s o f W e t l a n d s
his study found that there were an
estimated 39.8 million acres of wetlands
in the coastal watersheds of the eastern
United States in 2004. This represented
38 percent of the estimated total wetland
acreage in the conterminous United States (Figure 2).
Of all wetlands found in the coastal watersheds, 34.0
million acres (86 percent) were freshwater and 5.8
million acres (14 percent) were saltwater (estuarine or
marine) as shown in Figure 3.
In the saltwater systems, estuarine emergents were the
most prevalent type, making up an estimated 71 percent
(4.1 million acres) of all estuarine and marine wetlands.
Estuarine shrub wetlands comprised 14 percent of
the area and non-vegetated saltwater wetlands 15
percent.
In the freshwater system, forested wetlands made up
62 percent of the total freshwater wetland area in
the coastal watersheds. This was the single largest
freshwater category by area. Other freshwater wetland
types consisted of shrub wetlands that represented an
estimated 19 percent of the total freshwater wetland
area, emergents at 16 percent, and freshwater ponds
at 3 percent.
T FIGURE 2. Wetland Area of the Coastal Watersheds
(Great Lakes, Atlantic and Gulf of Mexico)
as a Percent of Total Wetland Area in the
Conterminous United States, 2004.
Wetlands of Coastal
Watersheds
38%
Remaining
Wetland Area
62%
FIGURE 3. Wetland Types in the Coastal Watersheds
(Great Lakes, Atlantic and Gulf of Mexico), 2004.
Estuarine and
Marine Wetland
14%
Freshwater
Wetland
86%
Results: Status of Wetlands
in Coastal Watersheds
S t a t u s a n d T r e n d s o f W e t l a n d s 15
Watersheds of the Atlantic and Gulf of Mexico coasts have almost the same amount of total wetland area:
15.9 million and 15.6 million acres, respectively. Watersheds of the Great Lakes had an estimated 8.4 million
acres. Not surprisingly, wetlands occupy more land area in some watersheds than in others (Figure 4).
Figure 4. Wetland density in the coastal watersheds of the Atlantic,
Gulf of Mexico, and Great Lakes, 2004.
Low: <10%, Medium: 10.1–17.6%, High: 17.7–32.5%, and Very High: >32.6%.
16 S t a t u s a n d T r e n d s o f W e t l a n d s
The estimated changes in wetland area for the coastal watersheds of the Great Lakes, Atlantic, and Gulf of Mexico
from 1998 to 2004 are shown in Table 4.
Table 4. Estimated change in wetland area for selected wetland categories for Coastal Watersheds of
the Great Lakes, Atlantic, and Gulf of Mexico, 1998 to 2004. The coefficient of variation (CV) for each entry
(expressed as a percentage) is given in parentheses.
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Marine Intertidal
135,970
(18.8)
134,180
(19.0)
-1,860
(69.9)
-1.4
Estuarine Intertidal Non-vegetated1 699,390
(12.3)
704,660
(11.9)
+5,270
(*)
+0.7
Estuarine Intertidal Vegetated2 4,950,430 4,885,450 -64,970 -1.3
All Intertidal (Saltwater) Wetlands 5,818,260 5,756,700 -61,560 -1.1
Freshwater Non-vegetated3 960,980 1,139,940 +178,960 +1.6
Freshwater Forested
21,064,220
(3.7)
21,100,450
(3.7)
+36,230
(*)
+0.2
Freshwater Shrub
6,735,910
(5.4)
6,293,530
(5.7)
-422,380
(42.5)
-6.6
Freshwater Emergent
5,612,020
(7.0)
5,539,680
(7.0)
-72,340
(101.3)
-1.3
Freshwater Vegetated Wetlands4 33,412,150 32,933,650 -478,500 -1.4
All Freshwater Wetlands 34,373,130 34,073,600 -299,540 -0.9
All Wetlands 40,191,380 39,830,280 -361,100 -0.9
*Statistically unreliable
1 Includes the category: Estuarine Intertidal Unconsolidated Shore.
2 Includes the categories: Estuarine Intertidal Emergent and Estuarine Intertidal Shrub.
3 Includes the categories: Palustrine Aquatic Bed, Palustrine Unconsolidated Bottom and Palustrine Unconsolidated Shore.
4 Includes the categories: Palustrine Emergent, Palustrine Forested and Palustrine Shrub.
Considering saltwater and freshwater systems together,
there was an estimated loss of 361,100 wetland acres in
the coastal watersheds between 1998 and 2004. Both
the Atlantic and the Gulf of Mexico coasts experienced
net wetland losses of 14,980 and 370,760 acres,
respectively. The Great Lakes coastal watersheds had
an estimated net gain of 24,650 acres. For all three
coastal watersheds, this equated to an average annual
net loss of about 60,000 acres over the 6-year period
of this study. There were wetlands gains in each of the
coastal regions, but wetland losses far outweighed the
gains, especially in the Gulf of Mexico (Figure 5).
S t a t u s a n d T r e n d s o f W e t l a n d s 17
Because Cowardin et al. (1979) defines “estuarine”
and “marine” wetlands as saltwater systems, no
estuarine or marine wetlands were identified in the
coastal watersheds of the Great Lakes portion of this
study. Shoreline wetlands of the Great Lakes were
included with other freshwater wetlands in the Great
Lakes coastal watersheds.
The majority of estuarine and marine wetlands fall into
three types: estuarine intertidal emergent wetlands
(salt and brackish water marshes), estuarine shrub
wetlands (mangrove swamps and other salt-tolerant
woody species), and estuarine and marine intertidal
non-vegetated wetlands. The latter category included
exposed coastal beaches subject to tidal flooding, as
well as sand bars, tidal mud flats, shoals, and sand
spits.
Coastal wetlands are subjected to a multitude of
anthropogenic stressors originating from the landward
side, as well as natural forces affecting change
from the sea. Stressors originating from land-based
activities include dredging, filling, shoreline hardening,
and a multitude of other human activities that
destroy wetlands. Seaward, events such as coastal
storms, tidal surge causing erosion and deposition,
saltwater intrusion, and inundation have the ability
to modify coastal wetland type and extent. Kennish
(2004) has summarized the major threats to estuarine
environments that include habitat loss, introduction of
contaminants, invasive species, freshwater diversion, sea
level rise, and subsidence, among others. EPA also has
provided indicators of coastal condition and identified
sources of environmental degradation affecting coastal
ecosystems to include discharges from municipalities
and industries and nonpoint-source runoff (EPA 2008).
FIGURE 5. Wetland Gains and Losses in the Coastal Watersheds of the
Atlantic, Gulf of Mexico, and Great Lakes, 1998 to 2004.
Acres
Atlantic Gulf Great Lakes
Trends in Coastal Saltwater Wetlands – 1998 to 2004
18 S t a t u s a n d T r e n d s o f W e t l a n d s
Between 1998 and 2004, saltwater wetlands declined
by slightly more than 1.0 percent. Estimated estuarine
and marine wetland losses (all intertidal wetland types)
were over twice as great along the Gulf of Mexico as
compared to the Atlantic coast (Table 5). Over 44,000
acres of these saltwater wetlands were lost in Gulf of
Mexico coastal watersheds during this study period.
The results from this study indicated that intertidal
marine non-vegetated wetland area (tidal flats and
shoals) declined by an estimated 6.0 percent along
the coastal areas of the Gulf of Mexico, whereas
they remained stable along the coastal areas of the
Atlantic.
The Gulf of Mexico had an estimated 36 percent more
area of saltwater wetland than the Atlantic in 2004.
The watersheds along the Gulf of Mexico contained
greater area of all wetland types with the exception
of marine intertidal flats and shoals. Both the Atlantic
and Gulf of Mexico coasts lost saltwater vegetated
wetlands between 1998 and 2004. Estuarine intertidal
vegetated wetland (saltwater marsh and shrubs) in
both of these regions declined by an estimated 65,000
acres (1.3 percent) overall.
Estuarine emergents (salt marsh) sustained the largest
losses, declining by an estimated 1.0 and 1.8 percent in
the Atlantic and Gulf of Mexico, respectively. Estuarine
salt marsh exhibited the largest declines of any
saltwater wetland type on both the Atlantic and Gulf of
Mexico coasts, declining by an estimated 62,500 acres.
The ecological value of estuarine salt marsh wetlands
has been well documented by a number of researchers
(Livingston 1984; Montague and Wiegert 1990; Watzin
and Gosselink 1992; Mitsch and Gosselink 2000; EPA
2008). The total monetary value of coastal wetlands
for storm protection has been evaluated by Costanza
et al. (2008). These studies indicate that the loss of
coastal wetland area has had adverse ecological and
economic effects.
S t a t u s a n d T r e n d s o f W e t l a n d s 19
Table 5. Estimated Changes to Saltwater (Estuarine and Marine) Wetlands in the Coastal Watersheds of
the Atlantic and Gulf of Mexico Coasts, 1998 to 2004. Percent Coefficient of Variation was Expressed as
(Standard Deviation/Mean) X 100.
Estimated Changes to Saltwater Wetlands of the Atlantic Coast
Atlantic Coast­—
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Marine Intertidal
105,130
(21.9)
105,160
(21.9)
+30
(71.4)
—
Estuarine Non-vegetated1 287,920
(21.4)
287,680
(20.8)
-240
(*)
-0.1
Estuarine Emergent
1,722,900
(6.0)
1,704,460
(6.0)
-18,430
(*)
-1.0
Estuarine Shrub
119,430
(16.6)
118,320
(16.6)
-1,110
(*)
-0.9
Estuarine Vegetated2 1,842.320
(5.8)
1,822,780
(5.7)
-19,540
(*)
-1.0
All Intertidal Wetlands - Atlantic
2,267,850
(6.1)
2,248,100
(6.0)
-19,750
(*)
-0.9
Estimated Changes to Saltwater Wetlands of the Gulf of Mexico Coast
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Marine Intertidal
30,830
(38.2)
28,950
(40.3)
-1,890
(68.8)
-6.1
Estuarine Non-vegetated1 411,470
(14.5)
416,980
(14.1)
+5,510
(*)
+1.3
Estuarine Emergent
2,428,970
(5.8)
2,384,880
(5.9)
-44,090
(20.0)
-1.8
Estuarine Shrub
679,140
(14.8)
677,800
(14.8)
-1,340
(69.6)
-0.2
Estuarine Vegetated2 3,108,110
(5.6)
3,062,680
(5.7)
-45,430
(19.4)
-1.5
All Intertidal Wetlands - Gulf of Mexico
Coast
3,550,400
(5.2)
3,508,600
(5.3)
-44,810
(24.7)
-1.2
*Statistically unreliable
1 Includes Estuarine Intertidal Unconsolidated Shore
2 Sum of Estuarine Emergent and Estuarine Shrub
Most saltwater wetland losses from both the Atlantic and the Gulf of Mexico resulted from inundation or saltwater
intrusion (Figure 5). This was observed most extensively in a region of the Atlantic coast extending south from Rhode
Island Sound to the mouth of Chesapeake Bay, which included areas along the coastal states of New York, New
Jersey, Delaware, Maryland, and Virginia. Wetlands were also lost to open saltwater in the western Gulf of Mexico,
20 S t a t u s a n d T r e n d s o f W e t l a n d s
principally along the coastlines of
Mississippi, Louisiana, and Texas.
These findings coincide with the
Coastal Vulnerability Index for the
U.S. Atlantic coast that shows the
relative vulnerability of the coast
to changes due to future rise in sea
level (Thieler and Hammar-Klose
1999).
Along the coastal fringe there
are regional differences in
geomorphology, land use, and
development trends. This may
explain why certain regions of the
Atlantic coastline seemed to be
particularly susceptible to wetland loss as a result of
inundation or saltwater intrusion. Thieler and Hammar-
Klose (1999) found portions of the Chesapeake Bay
region vulnerable to sea-level rise as a result of low
coastal slope, saltwater wetland as a common landform
type, and a relatively high rate of sea-level rise. In
contrast, the coastline of New England may be much
less vulnerable to sea-level rise due to its steep coastal
slope, rocky shoreline, and larger tidal range.
It has been speculated that the process of coastal
wetland retreat caused by saltwater inundation may
be more prevalent along the southeastern coastal
plain than in the northern Atlantic region. Williams
et al. (1999) found that along portions of the west
coast of Florida, saltwater intrusion might be replacing
forested habitats with salt marsh or more salt tolerant
species—perhaps a more subtle ecological shift than
the drowning of coastal vegetation by rising sea levels
associated with saltwater inundation. However, the
results from this study did not find coastal saltwater
wetland losses due to inundation or saltwater intrusion
along the coastal plain of the southeastern Atlantic,
nor on the Florida coastline of the Gulf of Mexico.
Intertidal wetlands lost to open saltwater were most
prevalent in the northern to mid-Atlantic regions, for
reasons undetermined by this study.
There were small losses of saltwater wetlands
attributable to development or other direct human
activities. Estimated losses of these types to urban
and rural development was 1.5 percent of all saltwater
wetland losses recorded during the period of this study.
Many federal and state agencies are involved in the
regulation, protection, and monitoring of saltwater
wetlands, coastal areas, and the species that inhabit
them. Additionally, coastal states also have established
coastal zone management plans, growth management
plans, and coastal resource agencies (Dahl 2000). These
programs and policies appear to have been effective in
limiting development in saltwater wetlands. There was
also very little wetland area restored in the intertidal
systems of the Atlantic or Gulf of Mexico between
1998 and 2004. The most notable gains in saltwater
wetlands were the result of conversion from deepwater
and freshwater wetlands along the Atlantic coast,
although these gains in area were negated by losses to
open saltwater on both coastlines. Wetland restoration
(re-establishment) or creation is more problematic
in the coastal watersheds, where land values fueled
by continued development are high. Additionally,
successful restoration of many coastal wetlands hinges
on consideration of physical processes including
flow, circulation, transport of nutrients, salinity, and
sediments (Sanders and Arega 2002).
Open Saltwater — 96.14%
FIGURE 6. Attribution of loss or conversion of saltwater wetlands in the
coastal watersheds of the Atlantic and Gulf of Mexico, 1998 to 2004.
Freshwater Wetlands — 0.32%
Urban Development — 0.86%
Other Uplands — 2.01%
Rural Development — 0.67%
S t a t u s a n d T r e n d s o f W e t l a n d s 21
Trends in Freshwater Coastal Wetlands – 1998 to 2004
An estimated 33 percent of all freshwater wetland area in the conterminous United States is found in the
coastal watersheds of the eastern United States (Table 6). Freshwater emergent wetlands generally contained
shallow water and were dominated by herbaceous plants. They included areas known as marsh, swale, slough,
wet prairie, wet savanna, reed swamps, and glades. Freshwater emergent wetland area declined in all coastal
watersheds between 1998 and 2004.
Table 6. Estimated Freshwater Wetland Acreage for Coastal Watersheds of the Atlantic, Gulf of Mexico
and Great Lakes as Compared to the Conterminous United States, 2004.
Wetland Category
Wetland Area in Acres
Coastal
Watersheds
2004
Conterminous
U.S.
2004
% Wetland
Area in Coastal
Watersheds, 2004
Freshwater Non-Vegetated1 1,139,940 6,229,600 18%
Freshwater Forested 21,100,450 52,031,400 41%
Freshwater Shrub 6,293,530 17,641,400 36%
Freshwater Emergent 5,539,680 26,147,000 21%
Freshwater Vegetated Wetland2 32,933,650 95,819,800 34%
All Freshwater Wetlands 34,073,580 102,453,800 33%
1 Includes the categories: Palustrine Aquatic Bed, Palustrine Unconsolidated Bottom and Palustrine Unconsolidated Shore.
2 Includes the categories: Palustrine Emergent, Palustrine Forested and Palustrine Shrub.
Freshwater wetlands in coastal watersheds exhibited
trends similar to those occurring elsewhere in the
nation. Non-vegetated freshwater ponds, both natural
and artificial, increased in area. Estimated pond acreage
increased by 18.0, 19.4, and 19.3 percent in the Atlantic,
Gulf of Mexico, and Great Lakes coastal watersheds,
respectively (Table 7).
Collectively, freshwater wetlands in coastal watersheds
declined by an estimated 0.9 percent between 1998
and 2004. Freshwater shrubs declined the most of
any freshwater wetland type, as an estimated 442,400
acres were lost during the period of this study. Large
losses of this freshwater wetland type in the Atlantic
and Gulf of Mexico coastal watersheds accounted for
this decline. There was a net gain in wetland shrub
area in the Great Lakes. The freshwater vegetated
wetlands (forest, shrub, and emergent types) found
in all watersheds included in this study declined by
an estimated 1.4 percent, whereas freshwater ponds
increased by almost 1.6 percent.
22 S t a t u s a n d T r e n d s o f W e t l a n d s
Table 7. Estimated Changes to Freshwater Wetlands in the Coastal Watersheds of the Atlantic,
Gulf of Mexico and Great Lakes, 1998 to 2004. Percent Coefficient of Variation was Expressed
as (Standard Deviation/Mean) X 100
Estimated Changes to Freshwater Wetlands in Coastal Watersheds of the Atlantic Coast, 1998 to 2004
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Freshwater Non-vegetated (ponds)1 404,300
(7.6)
475,370
(9.2)
+71,070
(31.2)
+18.0
Freshwater Forested
8,454,700
(4.9)
8,771,720
(4.8)
+317,020
(85.4)
+3.7
Freshwater Shrub
3,000,320
(7.9)
2,627,630
(8.2)
-372,690
(33.0)
-12.0
Freshwater Emergent
1,799,940
(10.9)
1,789,300
(10.9)
-10,630
(*)
-0.6
Freshwater Vegetated2 13,254,960
(4.0)
13,188,660
(4.0)
-66,300
(*)
-0.5
All Freshwater Wetlands
13,659,260
(3.9)
13,664,030
(3.8)
+4,770
(*)
+0.03
All Wetlands
(Atlantic Coast Watersheds)3
15,927,100
(3.4)
15,912,120
3.4
-14,980
(*)
-0.1
Estimated Changes to Wetlands in Coastal Watersheds of the Gulf of Mexico Coast, 1998 to 2004
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Freshwater Non-vegetated (ponds)1 349,210
(6.9)
417,030
(7.5)
+67,820
(18.1)
+19.4
Freshwater Forested
7,453,120
(4.8)
7,324,780
(5.1)
-128,340
(77.5)
-1.7
Freshwater Shrub
1,800,690
(8.6)
1,581,930
(8.9)
-218,760
(28.0)
-12.2
Freshwater Emergent
2,779,720
(9.9)
2,730,050
(9.9)
-49,670
(67.3)
-1.8
Freshwater Vegetated2 12,033,530
(4.1)
11,636,760
(4.2)
-396,770
(24.0)
-3.3
All Freshwater Wetlands
12,382,740
(4.0)
12,053,790
(4.0)
-328,950
(28.9)
-2.7
All Wetlands
(Gulf of Mexico Coast Watersheds)3
15,933,140
(3.3)
15,562,400
(3.3)
-370,760
(25.8)
-2.3
S t a t u s a n d T r e n d s o f W e t l a n d s 23
Table 7. Estimated Changes to Freshwater Wetlands in the Coastal Watersheds of the Atlantic,
Gulf of Mexico and Great Lakes, 1998 to 2004. Percent Coefficient of Variation was Expressed
as (Standard Deviation/Mean) X 100 (continued)
Estimated Changes to Wetland Area for Freshwater Wetlands in Coastal Watersheds of the Great Lakes,
1998 to 2004
Wetland Category
Area in Acres
Estimated Area,
1998
Estimated Area,
2004
Change,
1998 to 2004
Change
(percent)
Freshwater Non-vegetated (ponds)1 207,470
(12.1)
247,540
(10.0)
+40,570
(22.7)
+19.3
Freshwater Forested
5,156,400
(9.8)
5,003,950
(9.8)
-152,450
(75.0)
-3.0
Freshwater Shrub
1,934,900
(12.0)
2,083,970
(12.4)
+149,060
(76.2)
+7.7
Freshwater Emergent
1,032,360
(12.4)
1,020,320
(12.6)
-12,040
(*)
-1.0
Freshwater Vegetated2 8,123,660
(8.2)
8,108,240
(8.2)
-15,430
(74.6)
-0.2
All Freshwater Wetlands
(Great Lakes Watersheds)
8,331,130
(8.0)
8,355,780
(7.9)
+24,650
(44.0)
+0.3
*Estimate statistically unreliable.
1 Includes the categories: Palustrine Aquatic Bed, Palustrine Unconsolidated Bottom, and Palustrine Unconsolidated Shore
2 Includes the categories: Palustrine Forested, Palustrine Shrub and Palustrine Emergent
3 Includes all freshwater and saltwater wetlands
In the Great Lakes and the Atlantic regions, freshwater
forested and shrub wetlands reflect acreage changes
(interchange between wetland shrub and forested
categories) largely as a result of areas being harvested
for timber and becoming shrub wetlands, then maturing
and returning as forested wetlands. Forest and shrub
wetland area gains and losses were almost equal
between 1998 and 2004 in the Great Lakes and Atlantic.
Forested wetlands of the Gulf of Mexico region were
represented by many different ecological associations,
and included wet pine flatwoods, mixed hardwoods,
river swamps, cypress domes, and hydric hammocks.
These forested resources sustained substantial losses
overall.
Overall, the Gulf of Mexico coastal watersheds exhibited
substantial losses in freshwater wetlands. An estimated
396,800 acres of freshwater vegetated wetlands were
lost between 1998 and 2004. This rate of loss was
6 times higher than the rate of freshwater vegetated
wetlands losses in the Atlantic coastal watersheds. The
estimated wetland losses for all wetland types in the
Gulf of Mexico were almost 25 times higher than those
estimates for the Atlantic (371,000 acres versus 15,000
acres lost) over the course of this study (Figure 7 on
page 24).
The losses of all freshwater wetlands for the Atlantic,
Gulf of Mexico, and Great Lakes coastal watersheds
have been attributed to various causes, as shown in
Figure 8. Coastal development in both rural and
urban areas, loss to deepwater habitats (reservoirs),
silvicultural activities, drainage, and filling for other
types of development contributed to the losses of
24 S t a t u s a n d T r e n d s o f W e t l a n d s
coastal freshwater wetlands along the Gulf of
Mexico. The population of coastal counties in the
Gulf Coast region increased more than 100 percent
between 1960 and 2000 (U.S. Census Bureau 2003).
Because a disproportionate percentage of the
nation’s population lives in coastal areas, activities
that support municipalities, commerce, industry, and
tourism have created environmental pressures (EPA
2005). These development pressures have resulted
in substantial physical changes along many areas of
the coast, and coastal wetlands continue to be lost to
residential and commercial development (EPA 2008).
Other Development
Activities
59.45%
FIGURE 8. Attribution of Loss or Conversion of Fresh-water
Wetlands in the Coastal Watersheds of the
Atlantic, Gulf of Mexico and Great Lakes, 1998 to 2004
Agriculture
3.60%
Deepwater
14.50%
Intertidal Wetlands
0.05%
Urban and Rural
Development
22.40%
FIGURE 9. Net Gains and Losses (in acres) of
Coastal Wetlands in the Great Lakes Coastal
Watersheds, 1998 to 2004.
Acres Deepwater Development Other Lands Agriculture
-10,000
-5,000
0
5,000
10,000
15,000
20,000
25,000
2,500
-6,000
22,800
7,000
Figure 7. Areas of greatest coastal wetland loss in Gulf of Mexico.
Estimated net gains in freshwater wetland area were
seen in both the Great Lakes and the Atlantic coastal
watersheds. The Atlantic coastal region gained about
4,800 acres of freshwater wetlands between 1998 and
2004. The Great Lakes had the largest estimated increase
in freshwater wetland area. There was a net gain of an
estimated 24,650 acres over the study period, with wetland
area coming from fresh deepwater habitats, agricultural
lands, and the other uplands category (Figure 9).
S t a t u s a n d T r e n d s o f W e t l a n d s 25
n 2008, NOAA, FWS, the Fish America Foundation, and other partners restored a large area of
St. Vincent Island, a 12,000 acre barrier island in the Gulf of Mexico. Nearly 2,000 acres of
wetland needed to be restored as a result of 45 miles of roads blocking natural tidal flow for
many years. These wetlands and the surrounding Apalachicola Bay serve as a nursery for a
wide variety of fish species, including the striped bass, Gulf sturgeon, tarpon, red drum, spotted
seatrout and Gulf flounder. St. Vincent Island also provides sanctuary for a number of endangered and threatened
species. Loggerhead, green, and leatherback sea turtles come ashore to nest on its beaches, and wood storks stop
here during their migrations.
I
Restoration on an island is extremely complicated
logistically. All machinery, equipment, and personnel
had to be barged to the island, offloaded at the
docking location, and then hauled to the far end of the
island where the work took place. Working in marine
conditions created additional challenges, as the harsh
saline environment increased wear and equipment
break-downs, the soft sediment made it difficult to
move machinery, and the sensitivity of the surrounding
environment required special consideration be given to
methods and best management practices. All of these
factors added to the cost and time required to complete
the restoration.
Today, swaths of wetlands are recovering natural
function across areas once blocked by roads and
disrupted by water diversion. Birds and fish are also
returning as tidal flow returns to normal and water
quality improves. In combination with neighboring
restoration efforts at Tates Hell State Forest, St. Joe
Bay Buffer Preserve and Florida Fish and Wildlife
Commission’s Apalachicola Wildlife and Environmental
Area, the St. Vincent Island restoration will ensure
that the entire region benefits from this conservation
success.
Case Study: Re storation of Florida’s St. Vincent Island
Figure 10. St. Vincent Island restoration site, Florida, post-restoration.
26 S t a t u s a n d T r e n d s o f W e t l a n d s
oastal watersheds of the eastern United States contained about 11 percent of the total land area
in the lower 48 states and 38 percent of the wetlands by area. Yet these coastal areas experienced
roughly the same amount of wetland loss from 1998 to 2004 as occurred in the entire conterminous
United States in the 1990s. As with other status and trends reports on wetland acreage trends,
these data do not address the functionality of the wetlands lost, gained, or remaining unchanged
in acreage. CMore than half of the U.S. population lives in coastal
areas, and people continue to move to coastal areas
every year. Development was a major factor in the loss
of coastal wetlands, especially along the Atlantic and
Gulf of Mexico coasts, where it was the overwhelming
factor in the loss of freshwater wetlands.
Rising sea level, coastal subsidence, and erosion
processes were also important factors affecting
wetland loss and distribution, especially along
coastlines where the wetlands cannot migrate inland
because the shorelines are artificially hardened or too
steep. Coastal wetlands also appear to be vulnerable
to saltwater inundation in areas of the northern to
mid-Atlantic and the western Gulf of Mexico. To fully
recognize the impacts of climate change on coastal
wetlands, there will need to be a better understanding
of the linkages among upland, wetland, and oceanic
responses to changing conditions.
A majority of the coastal wetland loss (61,800 acres per
year) from 1998 to 2004 occurred in the Gulf of Mexico.
The loss of wetlands in southern Louisiana, estimated
at about 18,500 acres per year (U.S. Geological Survey
1995) accounted for only about one-third of the
wetland losses observed; much of the remaining losses
occurred in the upper portions of the watersheds and
were due to a combination of human-induced factors
including urban and rural development, silvicultural
operations, and other activities that drained or filled
wetlands. In effect, the same human uses that are
desired of coastal habitats are reducing their area and
lessening their value.
That is not to say that wetland losses are not occurring
in interior of the conterminous United States as well.
But those losses have been offset by wetland gains
that have resulted from re-establishment and creation
in inland regions, whereas in the coastal watersheds
of the Atlantic and Gulf of Mexico they have not been
similarly offset. Wetland restoration in coastal areas
is generally more expensive and logistically more
difficult than wetland restoration in inland areas due,
in part, to higher land costs, fewer suitable sites, and
competing interests (e.g., development). Additionally,
successful restoration of many coastal wetlands hinges
on consideration of physical processes including
flow, circulation, transport of nutrients, salinity, and
sediments (Sanders and Arega 2002).
However, the results of this study suggest that
wetland protection and restoration require more
attention in coastal watersheds. Otherwise, there is
a risk of reducing or losing the substantial ecological,
commercial, economic, and recreational services they
provide. Public policymakers and coastal managers
have been confronted with the daily task of finding
a balance between benefiting from economic growth
and mitigating the effects of growth on coastal
environments. This task will become more challenging
as the coastal population continues to grow in a limited
space, thereby exacting more pressure on the remaining
natural habitats, including wetlands.
Summary and Conclusions
S t a t u s a n d T r e n d s o f W e t l a n d s 27
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S t a t u s a n d T r e n d s o f W e t l a n d s 29
APPENDIX:
Definitions of Habitat Categories
WETLANDS5
n general terms, wetlands are lands where saturation with water is the dominant factor determining
the nature of soil development and the types of plant and animal communities living in the soil
and on its surface. The single feature that most wetlands share is soil or substrate that is at least
periodically saturated with or covered by water. The water creates severe physiological problems for
all plants and animals except those that are adapted for life in water or in saturated soil.
5 Adapted from Cowardin et al. 1979.
6 The U.S. Fish and Wildlife Service has published the list of plant species that occur in wetlands of the United States (Reed 1988).
7 U.S. Department of Agriculture has developed the list of hydric soils for the United States (U.S. Department of Agriculture 1991).
Wetlands are lands transitional between
terrestrial and aquatic systems where the
water table is usually at or near the surface
or the land is covered by shallow water. For
purposes of this classification wetlands must
have one or more of the following three
attributes: (1) at least periodically, the land
supports predominantly hydrophytes6, (2) the
substrate is predominantly undrained hydric
soil7, and (3) the substrate is non-soil and is
saturated with water or covered by shallow
water at some time during the growing season
of each year.
The term wetland includes a variety of areas that fall
into one of five categories: (1) areas with hydrophytes
and hydric soils, such as those commonly known
as marshes, swamps, and bogs; (2) areas without
hydrophytes but with hydric soils—for example, flats
where drastic fluctuation in water level, wave action,
turbidity, or high concentration of salts may prevent
the growth of hydrophytes; (3) areas with hydrophytes
but non-hydric soils, such as margins of impoundments
or excavations where hydrophytes have become
established but hydric soils have not yet developed;
(4) areas without soils but with hydrophytes such as
the seaweed covered portions of rocky shores; and (5)
wetlands without soil and without hydrophytes, such
as gravel beaches or rocky shores without vegetation.
Marine System – The marine system consists of
the open ocean overlying the continental shelf and
its associated high energy coastline. Marine habitats
are exposed to the waves and currents of the open
ocean. Salinity exceeds 30 parts per thousand, with
little or no dilution except outside the mouths of
estuaries. Shallow coastal indentations or bays without
appreciable freshwater inflow and coasts with exposed
rocky islands that provide the mainland with little or no
shelter from wind and waves are also considered part
of the Marine System because they generally support a
typical marine biota.
Estuarine System – The estuarine system consists
of deepwater tidal habitats and adjacent tidal wetlands
that are usually semi enclosed by land but have open,
partly obstructed, or sporadic access to the open ocean
and in which ocean water is at least occasionally diluted
by freshwater runoff from the land. The salinity may
be periodically increased above that of the open ocean
by evaporation. Along some low energy coastlines
there is appreciable dilution of sea water. Offshore
areas with typical estuarine plants and animals, such
as red mangroves (Rhizophora mangle) and eastern
oysters (Crassostrea virginica), are also included in the
Estuarine System.
I
30 S t a t u s a n d T r e n d s o f W e t l a n d s
M a r i n e a n d Estu a r i n e
S u b syste ms
Subtidal – The substrate is continuously
submerged by marine or estuarine waters.
Intertidal – The substrate is exposed and
flooded by tides. Intertidal includes the splash
zone of coastal waters.
Palustrine System – The palustrine (freshwater)
system includes all nontidal wetlands dominated by
trees, shrubs, persistent emergents, emergent mosses
or lichens, farmed wetlands, and similar wetlands
that occur in tidal areas where salinity due to ocean
derived salts is below 0.5 parts per thousand. It also
includes wetlands lacking such vegetation, but with all
of the following four characteristics: (1) area less than
20 acres (8 ha); (2) an active wave formed or bedrock
shoreline features are lacking; (3) water depth in the
deepest part of a basin less than 6.6 feet (2 meters) at
low water; and (4) salinity due to ocean derived salts
less than 0.5 parts per thousand.
C l a se s
Unconsolidated Botom – Unconsolidated bottom
includes all wetlands with at least 25 percent cover of
particles smaller than stones, and a vegetative cover less
than 30 percent. Examples of unconsolidated substrates
are: sand, mud, organic material, cobble gravel.
Aquatic Bed – Aquatic beds are dominated by
plants that grow principally on or below the surface
of the water for most of the growing season in most
years. Examples include seagrass beds, pondweeds
(Potamogeton spp.), wild celery (Vallisneria americana),
waterweed (Elodea spp.), and duckweed (Lemna spp.).
Rocky Shore – Rocky shore includes wetland
environments characterized by bedrock, stones, or
boulders which singly or in combination have an areal
cover of 75 percent or more and an areal vegetative
coverage of less than 30 percent.
Unconsolidated Shore – Unconsolidated shore
includes all wetland habitats having two characteristics:
(1) unconsolidated substrates with less than 75 percent
areal cover of stones, boulders or bedrock and; (2) less
than 30 percent areal cover of vegetation other than
pioneering plants.
S t a t u s a n d T r e n d s o f W e t l a n d s 31
Emergent Wetland – Emergent wetlands are
characterized by erect, rooted, herbaceous hydrophytes,
excluding mosses and lichens. This vegetation is present
for most of the growing season in most years. These
wetlands are usually dominated by perennial plants.
Shrub Wetland – Shrub Wetlands include areas
dominated by woody vegetation less than 20 feet (6
meters) tall. The species include true shrubs, young
trees, and trees or shrubs that are small or stunted
because of environmental conditions.
Forested Wetland – Forested Wetlands are
characterized by woody vegetation that is 20 feet (6 m)
tall or more.
Farmed Wetland – Farmed wetlands are wetlands
that meet the Cowardin et al. definition where the soil
surface has been mechanically or physically altered
for production of crops, but where hydrophytes will
become reestablished if farming is discontinued.
DEPWATER HABI TAT S
Wetlands and deepwater habitats were defined
separately because the term wetland does not include
deep, permanent water bodies. For conducting status
and trends studies, Riverine and Lacustrine were
considered deepwater habitats. Elements of Marine
or Estuarine systems can be wetland or deepwater.
Palustrine includes only wetland habitats.
Deepwater habitats were permanently flooded land
lying below the deepwater of wetlands. Deepwater
habitats include environments where surface water is
permanent and often deep, so that water, rather than
air, is the principal medium in which the dominant
organisms live, whether or not they were attached to
the substrate. As in wetlands, the dominant plants were
hydrophytes; however, the substrates were considered
nonsoil because the water is too deep to support
emergent vegetation (U.S. Department of Agriculture
1975).
Riverine System – The Riverine system includes
deepwater habitats contained in a channel, with the
exception of habitats with water containing ocean
derived salts in excess of 0.5 parts per thousand. A
channel is “an open conduit either naturally or
artificially created which periodically or continuously
contains moving water, or which forms a connecting
link between two bodies of standing water” (Langbein
and Iseri 1960).
Lacustrine System – The lacustrine system
includes deepwater habitats with all of the following
characteristics: (1) situated in a topographic depression
or a dammed river channel; (2) lacking trees, shrubs,
persistent emergents, emergent mosses or lichens
with greater than 30 percent coverage; (3) total area
exceeds 20 acres (8 ha).
UPLANDS
Agriculture8 – Agricultural land may be defined
broadly as land used primarily for production of food
and fiber. Agricultural activity is evidenced by distinctive
geometric field and road patterns on the landscape
and the traces produced by livestock or mechanized
equipment. Examples of agricultural land use include
cropland and pasture; orchards, groves, vineyards,
nurseries, cultivated lands, and ornamental horticultural
areas including sod farms; confined feeding operations;
and other agricultural land including livestock feed lots,
farmsteads including houses, support structures (silos)
and adjacent yards, barns, poultry sheds, etc.
8 Adapted from Anderson et al. 1976.
32 S t a t u s a n d T r e n d s o f W e t l a n d s
Urban: Urban land is comprised of areas of intensive use
in which much of the land is covered by structures (high
building density). Urbanized areas are cities and towns
that provide the goods and services needed to survive
by modern day standards through a central business
district. Services such as banking, medical and legal
office buildings, supermarkets, and department stores
make up the business center of a city. Commercial
strip developments along main transportation routes,
shopping centers, contiguous dense residential areas,
industrial and commercial complexes, transportation,
power and communication facilities, city parks, ball
fields and golf courses can also be included in the
urban category.
Forested Plantation: Forested plantations include
areas of planted and managed forest stands. Planted
pines, Christmas tree farms, clear cuts, and other
managed forest stands, such as hardwood forestry are
included in this category. Forested plantations can be
identified by observing the following remote sensing
indicators: 1) trees planted in rows or blocks; 2)
forested blocks growing with uniform crown heights;
and 3) logging activity and use patterns.
Rural Development: Rural developments occur
in sparse rural and suburban settings outside distinct
urban cities and towns. They are characterized by non-intensive
land use and sparse building density. Typically,
a rural development is a cross-roads community that
has a corner gas station and a convenience store
which are surrounded by sparse residential housing
and agriculture. Scattered suburban communities
located outside of a major urban center can also be
included in this category as well as some industrial and
commercial complexes; isolated transportation, power,
and communication facilities; strip mines; quarries;
and recreational areas such as golf courses, etc. Major
highways through rural development areas are included
in the rural development category.
Other Land Use: Other Land Use is composed of
uplands not characterized by the previous categories.
Typically these lands would include native prairie;
unmanaged or non-patterned upland forests and scrub
lands; and barren land. Lands in transition may also
fit into this category. Transitional lands are lands in
transition from one land use to another. They generally
occur in large acreage blocks of 40 acres (16 ha) or
more and are characterized by the lack of any remote
sensor information that would enable the interpreter
to reliably predict future use. The transitional phase
occurs when wetlands are drained, ditched, filled,
leveled, or the vegetation has been removed and the
area is temporarily bare.
For more information:
w w w. n m f s . n o a a . g o v / h a b i t a t
w w w. f w s . g o v / w e t l a n d s
National Oceanic and Atmospheric Administration
National Marine Fisheries Service
U.S. Department of Interior
Fish and Wildlife Service