California has lost over 90 percent of its wetlands.
Here, development encroaches on wetlands near
Cerritos Channel, Long Beach.

Photo: Lauma Jerkavics.

Land cover for 1950 and 1982 for

‘Tampa Bay, Florida, depicting land,
wetland, and seagrass changes. Source:
USFWS National Wetlands Research
Center and National Wetlands Inventory;
Florida Department of Natural Resources,
Marine Research Institute

acreages of wetlands, have both lost
about 46 percent of those wetlands (a
combined total of almost 17 million
acres).

Between the 1950s and the 1970s,
losses of coastal marshes and man-
groves were especially heavy, largely
because the public did not view these
habitats as valuable, and post-World
War I urban, residential, and indus-
trial development in the coastal zone
was booming. For example, the
airports at Boston, New York, and
New Orleans were all built on wet-
lands. By the mid-1970s, over half of
our original salt marshes and mangrove
forests had been destroyed. In the
freshwater marshes and forested
wetlands, drainage and clearing for
agriculture and silviculture were major
causes of loss. Since the mid 1970s,
loss rates have slowed, largely because
of the passage of a variety of federal
and state laws designed to protect
wetlands.

Population Growth and Urban
Development

Directly or indirectly, the major
threat to coastal wetlands is the
pressure of population growth. Over
half of the nation’s people live and
work within coastal counties that
encompass less than 10 percent of the
U.S. land mass. The population of
coastal counties is five times greater
than that of noncoastal counties
nationwide, and the coastal counties
along the Atlantic Ocean are 10 times
more densely populated than inland
counties.

This dense population puts
enormous pressure on all natural
resources, including wetlands. Histori-
cally, the rate of coastal wetland loss
has been directly proportional to
population density. People directly
destroy wetlands for urban develop-
ment and indirectly destroy wetlands
by water flow modifications, pollution,
and energy exploration and extraction.

Hydrologic Modification

Perhaps the least recognized but
most insidious threat to coastal we
lands has been extensive hydrologic
modifications, which indirectly damage
wetlands by changing their flooding
regimes. The U.S, Army Corps of
Engineers has been given the federal
responsibility for flood control.
Responding to urban growth in flood-
prone areas, the Corps constructed
levees along most major rivers. 'I'hese
levees prevent spring floods from
reaching the adjacent wetlands,
Tnland, dams and reservoirs have
reduced the water and sediment supply
to the coastal marshes. Around the
periphery of many estuaries, a dense
network of small canals has been dug
to speed water off urban and agricul-
tural land. The result is that water,
with its vital load of nutrients and
sediment, bypasses the wetlands
instead of flowing over them.

The Corps of Engineers also has
responsibility for navigation and in this
capacity has dredged thousands of
miles of canals, often across coastal
wetlands and estuaries. In Louisiana
and other areas along the Gulf coast,

an extensive network of canals for
access to subsurface oil, gas, and sulfur
deposits has also been dredged in the
coastal wetlands by private interests.
‘These canals are generally straight and
deep and are efficient conduits for both
fresh water flowing downstream and
tidal pulses, which can bring saltwater
much farther inland. As a result,
coastal wetland flooding patterns
change and salt marshes migrate
inland.

Agricultural Activities

The history of agriculture in
coastal wetlands is a fascinating one.
In the mid 1800s, wetlands were
considered wastelands, good only
when drained for cultivation. The
federal government, however, was not
anxious to incur the expense of
drainage, so in the Federal Swampland
Acts of 1845, 1850, and 1860, it
ceded to 12 coastal and three inland
states all land then unfit for cultivation
because of flooding. ‘These lands were
to be used for flood control and, where
feasible through the construction of
levees and by draining, for agriculture.
The states acquired 26.3 million acres
of land in this way, but by the turn of
the century, retained only about 5

private individuals, often at prices far
below estimated values. Ironically,
these new owners promptly applied
pressure through their representatives
in Congress to floodproof the land.
‘The taxpayer footed the bill for
drainage, lost millions of acres of
werlands, and is now in the position of



Coastal Wetlands

Coastal wetlands fringe the
shoreline of the United States, with
major occurrences along the margins of
the Gulf of Mexico and the south
Atlantic coast. Coastal wetland
ecosystems are organized and inte-
grated by the water that flows through
them. Each coastal system includes
both the wetlands immediately along
the ocean and those lining the rivers
and bays that drain into that part of the
coast. The entire hydrologic unit
functions as one entity. Fresh river
water, upland runoff, and local rainfall
flow seaward through the system, and
sea water, pulsed by the tides, flows
inland. The central basin, or estuary, is
a mixing zone between fresh and saline
waters. Freshwater marshes and fresh-
water forested wetlands occur farthest
inland, where rain and river water
dominate seawater. At the seaward
edge of the basin, wetlands are regu-
larly flooded by tidal waters, and large
expanses of tidal salt marshes occur. In
south Florida and the western coast of
the Gulf of Mexico, salt marshes are
sometimes replaced by saline forested
wetlands called mangroves.

Freshwater wetlands are typically
found at the inland portions of coastal
ecosystems where river discharge is
high. Fresh marshes can be tidally
influenced or nontidal, Many wetland
basins along the Atlantic coast are
funnel shaped, and tidal water moving,
up the funnel from the coast is forced
into ever narrowing channels. As the

Cattails are common along the
Atlantic and Pacific coasts
Photo: © C. C. Lockwood.

tide moves inland, its amplitude
increases while at the same time its
water freshens. Wetlands in this zone
are tidal but the water is fresh, In
contrast, on coasts with low tidal
energy such as the Gulf coast, the tide
diminishes inland. Water levels rise
and fall in a more unpredictable
manner as a result of winds that raise
water levels when they blow from the
ocean and lower water levels when they
blow from the land. In arid regions,
not enough fresh water enters estuaries
to support freshwater marshes.

The characteristic flooding of the
soil surface in wetlands stresses most
plants because it depletes the soil
oxygen they require to survive. Of the
hundreds of thousands of vascular
plants that inhabit the planet, only a
small percentage can
survive much flood-
ing, These are the
wetland plants. A
typical coastal fresh-
water marsh is charac
terized by only about
50 species of vascular
plants. On the Gulf
coast, the dominant
freshwater marsh
plants include maiden
cane, arrowheads, and
spike rushes. On the
Atlantic coast, pic
erelweed, wild ric
and cattails are
common. On the Pacific coast, cattails
and bulrushes dominate.

Freshwater forested wetlands, Iv is
not clear why freshwater marshes are
replaced by trees in some areas.
Perhaps a firmer substrate allows trees
to grow, or a different flooding regime
is required for tree seed germination.
At any rate, forested wetlands are
common features of coastal basins.
Although relatively diverse by wetland
standards, the number of species is also
limited because flooding limits the
amount of oxygen in the soils. There
are two broad types of forested wet
lands. Deep-water areas that are

Top: Wild rice Is commonly found
on the south Atlantic coast
Photo: USFWS

Bottom: Arrowheads in flower,
Atchafalaya delta, Louisiana
Photo: Ronald Paille, Louisiana
Sea Grant



federal statutes. Some in the agricul-
tural, forestry, and development
communities have suggested that
regulated wetlands should bewmore
rowly defined.

Another approach to wetland
protection is to buy the wetland
property and set itaside. Various
federal and state programs and some
private conservation organizations
(such as the Nature Conservancy)
purchase wetlands or easements‘on
wetlands for wildlife refuges, parks, and
wilderness areas:

Recently, governments have
developed programs that proyide
economic incentives for werland
preservation and disincentives for
wetland destruction...For ¢xample; the
federal tax code allows landowners who.
sell or donate their wetlands to the
government or to’a qualified wetland
conservation organization to claim the
value-as a‘charirable deduction on their
federal income tax returns.“Phe
“swampbuster” provision of the Food
Security Act of 1985 creates disincen-
tives for draining wetlands for cropland
by eliminating most farm program:
benefits to owners producing’com~
modity crops of wetlands drained after,

na

1985. Recent amendments to the
swampbuster provisions hayeschanged
the “trigger” for withholding benefits
from planting commodity crops to
dtaining the wetland. Voluntary
efforts by farmers haye/also helped to
slow the rate of werland loss from
agricultural practices in-recent-yéars.

Public Responsibility

Our, coastal wetlands cannot
survive the next century-unless more’
citizens take personal responsibility for
wetland. conservation: Wetlands’
provide benefits andvalues for all
people; they aré trust resoutees that we’
all must work’to protect.

As citizens, we can work together
in many ways to’slow wetland loss;and
degradation. Be“aware.of syhat is
happening, in your’Community that
affects wetlands. Support wetland
conservation by govertimenr agencies’
and. Conservation organizations:
Encourage the use of upland sités
rather than wetlands fordevelopment.
Participate iii the 404 review process
by commenting on a’ proposed project
if it isappropriate. If yoware ables buy
afederal duck stamp’ because, the
proceeds go toward wetland acquisi@

Willets at Ding Darling National Wildlife Retuge/ Florida. Photo; Jane Rohling.

tion, Donate to’conservation agencies
that try to acquire wetlands, participate
in 4 coastal Cleanup program, or
volunteer to help state and federal
agencies monitor coastal ecosystems.
Along the Chesapeake Bay and in
Rhode Island, North Carolina, and the
Pacific Northwest, volunteers collect
data to help scientists and managers
answer questions about the quality of
our coastal'systems and monitor efforts
to restore degraded systems,

Although most coastal: wetlands
are Owned by private citizens, we
Cannot expect theny to pay for all the
public benefits provided by wetlands:
‘Therefore, we must encourage our
legislators rovfind ways tomake
wetland conservation.and management
économically attractive for the indi-
vidual landowner:

‘here is no question thatwe are
entering the twenty-first century more
aware than’ ever of the problems of our
€nvironment, but we cannot wait until
tomorrow to protect our'coastal
resources, ‘Time will quickly tell
Whether America’s love affair with the
Coast will spell the demise or salvation
of her wetlands.



the

fragile

fringe

Rookery. Photo; ©.C.C. Lockwood.

permanent ponds and tidal creeks
during low water. “Most marsh
consumers, however, are small inverte-
brates that live out their lives’ buried in
the sediments.

What about the kitchen of this
unusual resort? Itis distinguished by
its abundance of food and by its
unique “soup recipe.” Earlier we
discussed reasons for the high produc-
tivity of coastal wetlands, “Salt marsh
grasses, although Often limited to one
species in a given\area, are more
productive than any cultivated
meadow. The fresh marshes farther
inland are more diverse, offering an
array of plants. In both the salt and
freshemarshes; grasses are garnished
with algae that grow on the moist
lower stems and on:the soil surface.
Birds and animals enjoy the seeds and
succulent roots and tubers of freshwa-
ter'marsh plants. On the whole
though, there isittléevidénce of
extensive grazing on living-marsh
plants—especially in salt marshes:

What is the famous soup? All the
evidence ‘suggests that the primary
food of the marsh isa mixture-of
decaying plant material, bacteria,
algae, and small invertebrates. The
decaying plant material, or detritns
(from the Latin‘ word for worn down
or disintegrated), is'broken down in
what is termed the detrital mill, The
“mill” works by both physical action
(waves, tides; and currents) and
biological action (shredding by
animals and microbial decomposition).

Detritus food webs are distinct
from grazing food webs (in Which
animals eat live plants) in three major
ways. First, bacteria, fungi, and other
microbes play an important role,
colonizing the'broken bits of plant
material and breaking,down fibrous
cellulose, which is not digestible by
most animals. Second, because most
decomposition occurs on'or in the
sediments, the scavenging animals are
predominantly bottom dwellers=for
example, microscopic wormlike



the fragile fringe

COASTAL
WETLANDS
OF THE

CONTINENTAL
UNITED STATES

Ecology,
Functions, and
Values of
Coastal
Wetlands

Wetlands are among the most
important ecosystems on earth. ‘Three
hundred million years ago, the swampy
environment of the Carboniferous
period produced and pri
the fossil fuel on which we now
depend. Today, wetlands continue to
provide us with valuable services. They
are sometimes described as “the
kidneys of the landscape” for their
function as removers of wastes from
both natural and human sources. They
form natural reservoirs, storing flood
waters and minimizing the damage
from severe storms. And they “store”
biotic diversity, providing a home for a
wide variety of important plants and
animals. Finally, they produce and
export food for a number of commer
cially important coastal fish and wildlife
species.

Unlike rocky coasts, which have
remained unchanged for millions of
years, most coastal marshes are measur-
ably different from the way they were a
few hundred or thousand years ago.
Wetlands occur where marine or river
sediments settle into shallow water and
build a platform on which marsh plants
can grow. At any time, the el
of the marsh surface is a balan
between land building upward from
sediment deposition, and land subsid-
ing from consolidation of marsh
sediments and the sinking of the land
mass. This balance may be affected by
many factors—a change in the water
supply that carries the sediments, a
change in the sediment supply, or even

Red mangrove at Rabbit Key, Florida.
Photo: © C,C. Lockwood.

served most of

Salt marshmallow. Photo: © C.C. Lockwood.

a change in elevation of the marsh
relative to the surrounding water (for
example, a global rise in se:
which in turn changes the frequency
and depth of flooding

These possibilities for wetland
change emphasize the dynamic nature
of wetlands. ‘To a large extent, the
characteristics of wetlands and the
manner in which they function are
determined by what is happening in
the areas surrounding those wetlands.
To understand why this is so, we must
understand how hydrology (patterns of
water flow) controls wetland sediment
supply and erosion, the availability of
oxygen and thus the organisms that
depend on that oxygen, the nutrient
supply and biological
production, and the
channels of access by
migratory animals.

cl),

Wetland Hydrology
Water is the life’s
blood of coastal
wetland ecosystems.
Most wetland pro-
cesses are determined



flooded most of the time are
dominated by bald
water tupelo or by pond cypress
and black gum. Less frequently
flooded areas, especially the
floodplains of rivers, are
dominated by willows, cottonwood,
several species of oak, water hickory,
green ash, and red maple

Salt marshes. Salt marshes are
flooded for varying periods by saline or
brackish water.
tions are typically flooded on every
tidal cyele: twice a day on the Atlantic
and Pacific coasts, once a day on the
Gulf coast. This environment is,

ypress and

Lower marsh clev

therefore, characterized by twin
stresses, flooding and salt. Of the
plants that can survive flooding, few

can also survive the salinities associated
with salt marshes. These few species,
for example, salt marsh cordgrass or
oyster grass (Spartina alterniflora)

and black needlerush (Juncus roemer
tanus), are extremely successful,
probably because they have little
competition from other plants. Salt
marsh salinities vary from nearly fresh
to very salty, depending on the amount
of rainfall and freshwater inflow. The
saltier the water, the fewer plant species
there are.

Bottomland hardwood swamps in
Louisiana's Atchafalaya basin are
flooded for part of each year.
Photo: © C.C. Lockwood.

Mangroves. The only trees
that can withstand the dual
stresses of flooding and salt are
tropical mangroves; in the
United States they occur only in
south Florida and, in stunted
form, along the western Gulf coast. In
south Florida, three mangrove spe
are common: Rhizophora mangle (red
mangrove), Avicennia germinans
(black mangrove), and Laguncularia
racemosa (white mangrove). The vigor
of the trees reflects the degree of
environmental stress, with the tallest
along the ban!
and stunted ones in stagnant water
where oxygen is most limited

es

of flowing creeks,

CONCEPTUAL DIAGRAM OF COASTAL MARSH ZONES

Limit of

* tidal influence



This publication is a Coastal
America Partnership Project.
Coastal America is a multi-agency
collaborative partnership to protect,
preserve and restore the coastal
environment. Participating partners
are:

Department of Agriculture
Department of the Air Force
Department of the Army
Department of Commerce
Department of Housing

and Urban Development
Department of the interior
Department of the Navy
Department of Transportation
Environmental Protection Agency

The partnership is coordinated by
the Executive Office of the
President

Funding of this reprinting of
“The Fragile Fringe" was provided
by the Fish & Wildlife Service,
National Marine Fisheries Service's
Office of Habitat Protection
(National Oceanic & Atmospheric
Administration), and the
Environmental Protection Agency's
Office of Water.

mas

LOUISIANA
SEA GRANT
College Program



ish and shellfish similarly share
the resource, shuttling between the
estuary and the adjacent ocean
Croaker, brown shrimp, white
shrimp, spotted sea trout, red drum,
menhaden, and striped bass all use
the marsh and adjacent estuary as a
nursery, usually spawning in the
ocean, moving into the estuary as
juveniles, and leaving as young
adults. Like the birds, their reserva
tions are for different times of the
year and different parts of the

and eaten by
microorganisms re
Plants 4
shredded by small
crustaceans, snails,
and others

enters the

Raw plant food
detrital mill

In addition to these periodic
visitors, coastal marshes also support
their own permanent animal
residents. The largest are two
rodents, the muskrat and, in the
south, the nutria (introduced from
South America), Both are vegetar-
ians. Alligators are also found in the
south, preferring fresh marshes.
Many birds, such as herons, ibises,
and bitterns, are also round
residents, especially in the south,
Small fish abound in the marsh
when it is flooded and retreat to

Deer in the Aransas National Wildlife Retuge, Texas.

Photo:

Attacked, colonized,

Feces, containing =)
plant remains

© CC. Lockwood.

Detritus-

a mixture

of microorganisms
and dead plant
remains

Aq uaye3

Shrimp, crabs,
small crustaceans,
and others

> Assimilated food
leaves detrital mill
as animal tissue

Marsh grasses support the detrital food web. Small animals shred the dead grass, enabling microorganisms to colonize it and break it down chemically so that other

animais can assimilate it and grow. Their waste products are recolonized by microbes and the cycle is repeated.




valued from as little as $10 per acre to
over $100,000 per acre. Each method
of evaluating wetlands focuses on
different criteria and all methods are
imprecise at best and misleading at
worst.

To be useful, any wetland valua
tion method must address a number of
questions. First, the evaluator must
decide on which wetland use(s) the
evaluation will focus. This is not a
technical question that can be an
swered objectively; it involves an
element of prefer
must also decide whether the wetland
will be used in its natural condition or
in a modified condition, say to enhance
fisheries, attract waterfowl, or purify
water.

Secondly, the evaluator must
decide how to evaluate the wetland
system as a whole. The value of a
wetland is more than its value for
fisheries or for hunting, yet many of
the wetland’s services are typically
ignored because they are difficult to
put into monetary terms.

Thirdly, the evaluator must address
the contextual value of the individual
wetland. Wetlands are part of larger
basin ecosystems; therefore, the
valuation method must address the
relative scarcity of that wetland type in
the basin as a whole, the upstream or
downstream systems that depend on
that wetland, and the role of the
wetland in the pattern of the landscape.

Finally, the valuer must address the
issue of wetlands as a common property
reson By this, we refer to the
products and services of wetlands that
belong to the public as a whole rather
than to the individual wetland owner.
For example, the shrimp and crabs
supported by wetlands are harvested by
fishermen in the estuary or ocean, not
by the owner of the wetland. Similarly,
the flood protection service of a
wetland is not primarily received by the
owner on site, but by people living
many miles downstream or inland.

Typically, the owner ofa salt
marsh may lease a wetland for several

nce. The evaluator

Working with marsh grasses in both field and greenhouse, wetland scientists have gained valuable
insights into the roles of salinity, subsidence, and waterlogging in marsh loss. Such information is vital
in designing comprehensive plans for wetland management. Photo: Ken Varden, Louisiana Sea Grant.

dollars an acre to fur trappers or
hunters, It is easy to understand, then,
why an offer to buy for urban residen-
tial development or to lease for oil
exploration may be attractive to an

owner, even though the public value of

royed may be
many times that of the money the

the wetlands thus des

Much of the debate

r wetland protection and regulation
revolves around this discrepancy
between the wetland’s value to the
landowner and its value to the public at
large.

owner receive

ov


the fragile fringe

nematodes, tiny crustaceans, and.
bottom-teeding fish and shellfish.
These animals eat decaying, plant
material, strip microbes from the-plant
fibers, digést them, and then excteté
the plant remains in fecal pellets that
can be colonized again by mi¢roorgan-
isms.

Finally, tides, storms, and espe-
cially the larger’ bottom-dwelling
invertebrates aid in breaking: down
detrital particles so rhat they can be
more readily decomposed. The
animals do this by shrédding the plant
particles during feeding. Ecologists
have estimated that excluding inverte=
brates from the decaying plant material
would reduce the decomposition rate
by as muchas 30:to 50 percent,

Wetland Values

The term valve is human centered.
Wetlands are valuable becauseiin
socideeonomic terms, they produce a
number of goods and services for
people: ‘The primary “goods” include
commercial harvests of timber, shrimp;
fish, crabs, crayfish, and fur..Ducks,
geese, deer, and’ game fish are recre-
ational “crops” from wetlands. Seép
vices provided by wetlands inelude
Water filtration and pfoteetion of
communities from’ floods and seyere
storms, The’ term Heritage value has
beer used to describe the importance
of wetlands as educational resources, as
repositories of biodiversity, as sources
Of aesthetic experience, and as, simply,
an/existing natural. phenomenoh

The importance of the goods that
wetlands produce has been extensively
documented, For example, 90 percent
of the Gulf coast fishery (including
shellfish) depends on estuaries and
wetlands during some part of its life
cycle. This fishery is the largest in the
countty, supporting thousands of
people-directly and indirectly. As
another example, inthe best years,
700,000 waterfowl are produced in the
marshes bordering the southern states/

It is harder to document the value

of the services provided by wetlands,
partly because nor all wetlands funetion
in the same’ way or atthe same level of
efficiency Neverthelessynumerous
studies show rhat wetlands remove
sediments, nutrients, and toxins ffom
the water: “As a result, wetlands are
now being created, and/used for final
treatment of domestic sewage from a
number of)snaall cities.
studies show that this process can be
lés§ expensive and just as ¢fficient/as
thé construction and operation of a
tertiary treatment plant,

Wetlands along rivers draining into
coastal zones provide flood protection
by‘detaining water from, heavy rains,
thus reducing peak flows downstream
Coastal wetlands ptovide flood protec
tion during severe stormsjand hurri+
canes by/diminishing the amount of
water that travels inland with the storm

Zconomic

Coastal wetlands are poptlar:
sites for birdwatching.
Photo: Jane Robling

surge. Wetlands also'trap sediments,
limiting erosion. Estuatine channels
bordered by wetlands erode much

more slowly than unvegetated banks

Although difficult to quantify, the
heritage valuesof wetlands is receiving
increasing-attention. Wetlands are
used, extensively for nonconsumptive
recreation such as wildlife observation,
natiire photography, and canocing,
Wetlands are also tremendously
valuable as\reserves of biological
diversity. For example, wetlands
comprise more than half of the areas
identified as critical habitar under
provisions of the Endangered Species
Act,

Tt has been tempting to apply an
economic value to/wetlands in order to
isions about alternate
uses of the resource Ina number of
studies, coastal wetlands have been

make easier de:



by the depth, duration, frequency, and
cnergy of flooding water, When water
rises and covers a marsh, it replaces air
in the soil, leaving much less oxygen

available to the plants and animals
The oxygen deficiency in the soil
restricts soil microorganisms to those
that can use chemicals other than

oxygen in their metabolism. Microor-
ganisms able to do this are the sulfate-
reducing bacteria. These bacteria can
substitute the sulfate in seawater for
the oxygen that is normally used to
derive energy from food. The end
product of this process, hydrogen
sulfide, has the characteristic rotten-
egg odor noticeable when the soil in a
salt marsh is disturbed.

The influence of water is not
limited to its effect on the oxygen
supply in the sediments. Water is also
the vehicle that transports materials
such as nutrients and sediments into
and out of wetlands, We have dis-
cussed briefly how suspended sedi-
ments transported by water are vital in
the formation and continuing existence
ofa marsh. These same waters, when
focused into shallow depressions, scour
tidal channels. A typical salt marsh is
interlaced with a network of tidal
channels,

‘The same flooding waters carry
plant-nourishing nutrients into the
marsh, Scientists have found that in
Atlantic coast salt marshes, the greater
the tidal amplitude, the more produc
tive the marsh. This relationship has
been termed the tidal subsidy. Large
tides carry more water and nutrients
into the marsh than small ones and
thus stimulate plant growth. The
subsidy is, in effect, a natural fertiliza-

Great blue heron in marsh,
Photo: © C.C. Lockwood.

The muskrat is a
permanent resident

in the coastal marshes

of the Blackwater National
Wildlife Refuge, Maryland.
Photo: USAWS.

tion that makes many salt marshes as
productive as the most vigorous
agricultural croplands.

Coastal ecosystems receive virtually
all the water flowing off the continen-
tal United States—waters carrying
sediments, fertilizers, and pesticides
from the nation’s farms; waters con-
taining the treated and untreated
sewage from thousands of communities
across the country; and waters con-
taminated with heavy metals and exotic
organic chemicals from thousands of
factories along the nation’s rivers,
and estuaries. Coastal wetlands
Vv some of these materials,
transform inorganic nutrients to less
damaging organic forms, and bury
others in their sediments,

For decades it has been recognized
that flooding waters carry organic
materials out of coastal marshes to
serve as food for fish and shellfish in
adjacent waters. In Louisiana, after
high spring floods sweep through the
marshes, the adjacent waters are rich
with “coffee grounds,” decaying
organic material from the marshes,
which support a dense population of
small, bottom-dwelling invertebrates.
This mixture is a rich source of food
for the small migrating fish and
shellfish that are in the estuary during,
this time of year. Small fish and
shellfish also get much of their food by
foraging on the marsh surface itself
when it is flooded.

Wetland Food and Food Chains
Coastal wetlands are perhaps best
known for their support of migratory
birds, fish, and shellfish. From this
point of view, the wetlands might be

thought of as a resort, visited sea
ally for its excellent food. Each visitor
to the resort stay
the good meals and then moves on.
ally programmed
with “standing reservations,” so that it
returns year after year at the same time.
And each shares the resort with others,
but not always at the same time.

‘The coastal wetlands of the
northern Gulf of Mexico illustrate this
analogy. Wading birds, grackles, and
blackbirds dominate during the
summer. Teal and pintail ducks visit
during late fall, move on to South
America for the winter, then stop again
on the way north in the spring. Other
ducks, such as canvasbacks and red-
heads, spend the entire winter in Gulf
coastal marshes, flying to Canada in
the spring to nest and returning to the
Gulf coast again in late fall. Migratory
songbirds stop by only briefly in fall
and spring on their travels to and from
South Americ:

son-

for a while to enjoy

Each species is genetic



the fragile fringe

COASTAL
WETLANDS
OF THE

CONTINENTAL
UNITED STATES

Introduction

In the ecologist’s language, wetlands are known as ecotones, or
transitional areas, sandwiched between permanently flooded deep-
water environments and well-drained uplands. At one edge they are
predominantly aquatic and at the other mostly dry. The boundaries
of each are often subtle, like the blurred borde: of green between
bleeding blue and yellow dyes in a fabric. Typically, ecotones are
richer than cither adjacent habitat because they have attributes of
both. They often contain more plants and animals, and may produce
more organic material than either adjacent habitat.

In the last 50 years, ecologists have discovered that wetlands in
natural ecosystems perform a number of important roles. They help
to moderate extreme floods, help to maintain the desirable qualities
of water, and are home to many unusual plants and commercially
important animals like shrimp and crayfish. At the same time, wet-
lands are vulnerable systems, easily filled or drained for other uses,
and they are rapidly disappearing. Beginning in the 1970s, wetland
protection began to be written into federal and state laws. These
statutes required a clear definition of wetlands.

The three common characteristics of all wetland definitions are:
(1) Wetlands are periodically flooded or at least saturated to or near
the surface with water. (2) Wetlands have unique soils (hydric soils)
that differ from those of adjacent uplands, (3) Wetlands support
plant species adapted to wet conditions (hydrophytes), and do not
support vegetation intolerant of flooding.

Cypress knees, Lac des Allemands, Louisiana.
Photo: Ronald Paille, Louisiana Sea Grant.


== Upland Range / Forested
eal Urban / Bare Upland / Agriculture

buying parcels back at inflated pric

Coastal wetlands have been used
for agriculture for centuries. The high
marshes of the New England coast
were used extensively for cattle grazing
and for native hay production. In
South Carolina, farmers took advan
tage of the tidal pulse of fresh water in
coastal wetlands to manage them for
rice production, an extremely profit-
able occupation during the nineteenth
and early twentieth centuries. Many of
these old rice fields are still identifiable
and some are now managed for
migratory waterfowl.

In Louisiana, large rectangular
ponds are all that remain of earlier
attempts to turn coastal marshes into
sugar cane fields. The marshes were
leveed and drained with enormous coal
or wood-fired pumps, the ruins of
which are still standing. However, the
farmers failed to consider two factor:
first, organic soils exposed by draining
rapidly subside and, second, Gulf
hurricanes are relatively frequent and
severe. Subsidence lowered the land,
making it increasingly expensive to
drain, and hurricanes breached the
levees, flooding the fields. Few marsh
sugar cane fields remain in Louisiana
today.

Water Pollution
Water pollution may not be the
most dramatic threat to coastal wet-

[EGG Freshwater wetlands

ee) Vegetated Flats / Mangrove / Marsh

lands but it is probably the most
difficult to control. Water pollution
sources fall into two categories, point
and nonpoint, Point sources are
identifiable discharges from a pipe or
other single source that can be quanti
fied, monitored, and, presumably,
controlled. The U.S. Environmental
Protection Agency requires that
permits be issued limiting pollutants in
these discharges. Examples of point-
source discharges include outfalls from
sewage treatment plants, paper mills,
and industrial plants. Nonpoint-source
discharges result from land runoff.
‘They do not originate from discrete
sources and therefore are not casy to
control. Examples include urban street
runoff and farm runoff that contains
manure, fertilizers, and pesticides.
Both point and nonpoint sources
of pollution may be located many miles
upstream from the coastal wetlands
that they influence; sometimes they
originate in another state and, thus,
another jurisdiction from the affected
wetlands. Furthermore, any one
discharge may involve only small
amounts of chemicals that are rapidly
diluted to unmeasurable concentra-
tions in the receiving stream, but when
multiplied many times or in combina-
tion with other chemicals, these small
discharges may form significant
concentrations that have detrimental
biological effects. Only recently has

=] Seagrass
HE Water Tidal Fiats

the issue of cumulative impact man-
agement begun to receive serious
attention.

Case Studies of Wetland Loss

San Francisco Bay. San Francisco
is considered by many to be the major
USS. estuary most modified by human
activities, Although the first Spanish
soldiers and missionaries arrived in the
bay area in 1769, San Francisco
remained a relatively isolated frontier
town until gold was discovered in the
Sierra Nevada foothills in 1848. In
just two years, the population grew
from fewer than 400 to over 25,000.
By 1900, most of the marshes in the
bay were gone.

The causes of wetland loss and
estuary modification are numerous.
From 1853 to 1884, gold miners used
a high-pressure water jet to wash the
gold from ore deposits in sluiceways.
This hydraulic mining process washed
tens of millions of cubic meters of
sediment and debris into the bay
annually, filling huge portions of
Suisun, San Pablo, and Central bays.
In 1884, hydraulic mining was stopped
by court order, but it took decades for
the sediments deposited over the
previous 30 years to be flushed from
the river channels.

Agriculture was another major
cause of wetland loss. By the 1920s,
almost all the freshwater marshes in the



the fragile fringe

TINENTAL
TED STATES

Coastal
Wetland
Management
and
Protection

The success of coastal monitoring and replanting programs depends on the efforts of citizen volunteers.

Photo: Florida Phosphate Industries, Inc.

As we have seen, there have been
many causes for the loss of our coastal
wetlands, and until relatively recently,
public indifference and government
policies encouraged that loss. Fortu-
nately, this situation has changed.
Recent polls show that an overwhelm
ing majority of Americans want to
preserve and protect wetlands, even if
it means additional cost to them. The
federal government and most coastal
states have implemented a variety of
programs specifically directed toward
wetland management and protection.

Wetland Protection Programs

The cornerstone of the federal
effort to regulate wetlands is the so-
called “404 program,” Section 404 of
the Clean Water Act. Under 404, the
discharge of dredged or fill material
into waters of the United States,
including most wetlands, requires a
permit from the U.S. Army Corps of
Engineers. The Corps is required to
ARshe aipaBle HOuce OE petiult
application to inform citizens about the
proposed project and solicit their
opinions on it. Other government

agencies and interested organizations
can also provide their comments. The
Corps bases its decision to grant a
permit on a review of environmental
impacts, using standard guidelines
developed in cooperation with the
Environmental Protection Agency, and
the balance between the public costs
and benefits of the proposed project.

Many activities that damage or
destroy wetlands have not been
regulated under the 404 program
because they do not involve the
discharge of dredged or fill material.
Some of these activities may be in-
cluded under the program in the
future.

‘The U.S. Army Corps of Engi-
neers, Environmental Protection
Agency, Soil Conservation Service, and
Fish and Wildlife Service use criteria for
delineating “jurisdictional wetlands”
based on the three primary characteris-
tics of wetlands (flooded or saturated
site, hydric soils, and wetland plants
present) discussed at the beginning of
this publication. Jurisdictional wet-
lands are those subject to regulation
under the 404 program and other



COASTAL
WETLANDS
OF THE

CONTINENTAL
UNITED STATES

Written by

Mary C. Watzin

U.S. Fish and Wildlife Service

Vermont Cooperative Fish and Wildlife Research Unit
University of Vermont

Burlington, Vermont

and

James G. Gosselink

Professor Emeritus
Louisiana State University
Baton Rouge, Louisiana

Produced by
Louisiana Sea Grant College Program

Louisiana State University
Baton Rouge, Louisiana

and

U.S. Department of the Interior

Fish and Wildlife Service
National Wetlands Research Center
Lafayette, Louisiana

In cooperation with
National Oceanic and Atmospheric Administration

Office of Ocean Resources Conservation and Assessment
Strategic Environmental Assessments Division
Rockville, Maryland

and

Fish and Wildlife Service

National Wetlands Inventory
Washington, D.C,



ACKNOWLEDGMENTS

James B. Johnston, U.S. Fish and Wildlife
Service, and Elizabeth B. Coleman,
Louisiana Sea Grant College Program,
served as project officers for this
publication. Data were provided by Dan
Basta, Don Field, and Tony Reyer, National
Oceanic and Atmospheric Administration;
Bill Wilen and Tom Dani, U.S. Fish and
Wildlife Service, National Wetlands
Inventory; and Ken Haddad, State of
Florida.

Ken Varden, Louisiana Sea Grant College
Program, designed the publication and
Bonnie Grayson assisted with computer
graphics. Sue Lauritzen, U.S. Fish and
Wildlife Service, compiled the
photographs. The manuscript was edited
by Elizabeth Coleman, Louisiana Sea
Grant, and Gaye Farris, U.S. Fish and
Wildlife Service.

Cover photo, Cameron Beach at Sunrise,
courtesy of Bill Turnbull, Turnbull Images,
Cameron, Louisiana.

The Louisiana Sea Grant College Program
is a part of the National Sea Grant College
Program maintained by the National
Oceanic and Atmospheric Administration,
U.S. Department of Commerce, and is also
supported by the state of Louisiana.

A companion report to this educational
brochure describes NOAA's national data
base on the distribution and abundance
of coastal wetlands in the continental
United States: National Oceanic and
Atmospheric Administration and the U.S.
Fish and Wildlife Service. 1991. Coastal
wetlands of the United States: an
accounting of a valuable national
resource. NOAA, Strategic Assessments
Division, Rockville, MD.

This document may be cited:

Waizin, M.C., and J.G. Gosselink. 1992.
The fragile fringe: coastal wetlands of the
continental United States. Louisiana Sea
Grant College Program, Louisiana State
University, Baton Rouge, LA; U.S. Fish and
Wildlife Service, Washington, DC; and
National Oceanic and Atmospheric
Administration, Rockville, MD.

dune 1992



the fragile fringe

c
Ww

ASTAL
TLANDS

NTINENTAL
ITED STATES

)
E
F THE
t')
N

Status and
Trends of

Coastal
Wetlands

Residential development in Florida.
Photo: James Johnston, USFWS.

Coastal wetlands in the lower 48
states cover more than 26 million acres
(see table). This a
about 5.5 million acres of salt marshes
and mangroves immediately along the
coast and more than 20 million acres
of freshwater marshes and forested
wetlands along the ri
that drain into the oceans. Although
coastal ecosystems account for only
about 9 percent of the land area in the
lower 48 states, this zone includes
about 30 percent of the wetlands in
these states.

age includes

sand estuaries

Losses of wetlands since the
United States was colonized in the
1700s have been tremendous. The
U.S. Fish and Wildlife Service estimates
that about 220 million acres of wet-
lands existed in the contiguous United
States in colonial times. Today, only
about 103 million acres, or 47 pet
of those wetlands remain, Statistics for
the coastal zone only do not exist, but
one coastal state, California, has lost
more than 90 percent of its original
wetlands. Florida and Louisiana, the
two states with the greatest original

ic

at

COASTAL WETLAND ACREAGE IN THE CONTINENTAL U.S.*

Salt Fresh Forested TOTAL
Marsh Marsh Wetlands** WETLANDS.
Atlantic Coast 1,651,900 1,490,600 8,410,900 11,553,400
Gulf of Mexico 2,496,600 2,751,100 8,211,800 13,459,500
Pacific Coast 121,900 291,200 757.100 1,170,200
Total 4,270,400 4,532,900 17,379,800 26,183,100

‘excludes Alaska, the Great Lakes, and Hawaii
“includes mangroves

Source: National Oceanic and Atmospheric Administration, National Ocean Service, Office of
Oceanography and Marine Assessment, Strategic Assessment Branch.


delta area, at the confluence of the
Sacramento and San Joaquin rivers,
were diked and converted to farmland.
The diking and filling of tidal marshes
for fodder fields continued until the
1970s.

In the South Bay, diking for salt
production in evaporation ponds began
in 1856 and continues today. About
two million tons of salt are produced
annually in the bay area.

At the same time that wetland
diking and filling were progressing,
fresh water entering the bay was being
diverted through a system of dams,
reservoirs, and canals. Today, about
40 percent of the historic fres
flow is diverted for irrigation and
municipal consumption; another 24
percent of the volume of “fresh water”
entering the bay today is composed of
agricultural, industrial, and domestic
wastewater. This has enormous
implications for the remaining wet
lands, and many indeed have poor
water quality and reduced productivity.
Most of the remaining tidal marshes.
are isolated and there is little opportu-
nity for wetland expansion because of
numerous dikes and urban develop-
ment.

Louisiana, Enormous losses have
occurred recently in wetland habitats
along the Gulf of Mexico, especially in
coastal Louisiana. In the last century
790,000 acres of coastal wetlands were
converted to agricultural, urban, and
industrial use. Between 1956 and
1978, about 680,960 acres of wetlands
deteriorated into open water. The
U.S, Army Corps of Engineers esti-
mates that before the year 2040, nearly
1,000,000 additional acres of wetlands
will be lost, an area larger than the
state of Rhode Island.

The causes of this wetland loss are
both natural and human-induced. In
much of coastal Louisiana, wetlands
formed on delta deposits from sedi
ments in flood waters of the Mississippi
River. Over the last 7,000 years, the
Mississippi River has changed course at
least four times. When the river
changed courses, sediments left in the
abandoned delta lobes compacted and
sank under their own weight, causing
the marsh to deteriorate. Until
relatively recent times, this natural
marsh deterioration in abandoned delta

lobes was offset by marsh formation in
the newest, active delta lobe.

But when the 900-mile levee
tem along the Mississippi River was
completed in the early twentieth
century to protect growing towns from
flooding, the sediment-laden river
water could no longer spill over the
banks to deposit its load of silt in the
wetlands. Thus, new marsh accretion
rates could no longer offset marsh
deterioration in abandoned delta lobes.
River water is now contained in the
main channel of the river and the
sediments needed to build and main-
tain the wetlands are shunted directly
into the Gulf of Mexico.

Because southern Louisiana is an
extremely flat plain, small changes in
land elevation relative to water level
can result in large changes in the

amount of wetland. An action or event

that lowers the marsh surface by as
little as an inch may cause widespread
marsh deterioration. ‘The withdrawal
of oil, gas, water, salt, and sulfur from
near-surface deposits can contribute to
land subsidence, lowering the marsh
surface and drowning the marshes.
Worldwide sea level rise, although
small (6 to 12 inches
per hundred years),
may also be contribut-
ing to marsh drowning.
Wetland loss from
sediment starvation and
marsh drowning has
been accelerated and
exacerbated by other
human activities in the
coastal zone. An
extensive network of
canals for navigation
and for oil and gas
exploration has been
dredged in coastal
Louisiana, ‘The dredging of canals
directly destroys wetlands by convert-
ing them to open water and spoil piles.
Spoil piles block marsh flooding and
draining and thus increase sediment
deficits in the marshes. Waterlogging

in undrained marshes leads to increased

plant stress and lower productivity.
Canals may funnel saltwater into
previously brackish or freshwater
marshes, changing the plant commu-
nity and perhaps ultimately causing the
plants to die. Canals may also shunt

fresh water containing nutrients and
sediments vital to plant productivity
through the wetland system, byps
the wetland plain itself.

Solutions to Louisiana’s wetland
loss problem will require a comprehen-
sive plan of action, incorporating both
large-scale federal actions and local
wetland management.

ing,

Louisiana's productive coastal marshes are
rapidly eroding into open ponds and lakes, a
loss that threatens the survival of the state's
renewable natural resources.

Photo: Louisiana Sea Grant.