Status and Trends of Emergent and Submerged Vegetated Habitats, Gulf of Mexico, U.S.A.


United States
Environmental Protection
Agency
Office Of Water
Gulf Of Mexico Program
Stennis Space Center, MS 39529
EPA 800-R-92-003
September 1992
Status And Trends Of
Emergent And Submerged
Vegetated Habitats,
Gulf Of Mexico, U.S.A.
                           Recycled/Recyclable
                           Printed on paper that contains
                           at least 50% recycled fiber

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            U.S. ENVIRONMENTAL PROTECTION AGENCY
                   GULF OF MEXICO PROGRAM
             HABITAT DEGRADATION SUBCOMMITTEE
                          REPORT ON
     THE STATUS AND TRENDS OF EMERGENT AND SUBMERGED
       VEGETATED HABITATS OF GULF OF MEXICO COASTAL
                         WATERS, U.S.A.
       EDITORS: THOMAS DUKE, TECHNICAL RESOURCES, INC.
WILLIAM L. KRUCZYNSKI, U.S. ENVIRONMENTAL PROTECTION AGENCY

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                                TABLE OF CONTENTS
                                                                                 Page

Habitat Degradation Subcommittee  . . .	     v

Conversion Factors	,«,,.,,,,..	, ......    yi

Preface	   Vii

Executive Summary	   vm

Introduction .	     i

Inventories of Coastal Habitats	     7

Functions and Values of Gulf Coastal Habitats	   26

Quality of Coastal Habitats		   42

Living Resources	   61

   Marshes	   61
   Seagrasses	   66
   Mangroves	   71
   Endangered Species and Habitats  .	'.'.I'.'.'.'.'.'.'.'.   76

Case Histories	   86

   Texas	   86
     Barrier Islands	   89
     Estuaries	   89
       Matagorda Bay	   92
       Brownsville  	      93
       Neches River	   93
       Galveston Bay  	   94
   Florida  	'.'.'.'.'.'.'.'.'.   98
     Tampa Bay	-.'.'.'.'.'.'.'.'.'.'.   99
     Charlotte Harbor	. .... .1 ...........  103
   Louisiana  	' ' '  iQ6
     Atchafalaya Basin	  108
     Barataria Basin .	'.'.'.'.  110
     Calcasieu Basin/Chenier Plain	'.'.'.'.'.'.'.'.'.  115
   Alabama	  117
     Mobile-Tensaw River Delta	  117
     Mobile Bay	  119
   Mississippi	[ ]    120

Conclusions  	   125

Bibliography	   130

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LIST OF TABLES
Page
Table 1. Wetlands Acreage (Acres) Changes from 1950's to 1970's 7
Table 2. Wetland Acreage (Acres) in the Gulf of Mexico 8
Table 3. Coastal Wetlands Classification for the Gulf of Mexico 10
Table 4. Emergent Wetlands (Acres) in Coastal Counties 12
Table 5. Totals (Acres) of Selected Wetlands by State for the Gulf of Mexico 15
Table 6. Coastal Wetlands by Estuarine Drainage Area 16
Table 7. Total Acreage (Acres) of the Coastal Barrier Resource System (CBRS) Sound within
the Gulf States Area 17
Table 8. Texas Coastal Habitats (Acres) 21
Table 9. Acreage (Acres) of Selected Habitats in Florida 22
Table 10. Calculations of Total Loss/Accretion (Acres) in the Mississippi River Deltaic
Plain Recorded on Quadrangle Maps 23
Table 11. Production Rate for Various Wetland Habitats 27
Table 12.
Table 13.
Table 14.
Table 15,

Table 16.
Table 17.
Table 18.

Table 19.
Table 20.
Table 21.
Table 22.
Table 23.
Preliminary Estimates of Animal Secondary Production, Consumption, Standing
Stock and Turnover for Different Ecosystems 36
Characteristics of Some Gulf of Mexico Estuaries . 37
Changes in Area by Habitat in Louisiana's Coastal Zone from 1955/56-1978 ... 48
Proposed Projects and Acres of Habitat Involved in NMFS Habitat Conservation
Efforts From 1981 through 1987 , ,.-.... 53
Shellfish Harvest Classification by States in 1985 55
Examples of Temporary Closures of Approved Waters in the Gulf of Mexico ... 56
Areal Changes (in Acres) in Selected Coastal Barrier Resource Systems Units,
ca. 1940's to 1982 . •
60
Estimated Fur Catch per 1,000 Acres of Coastal Marsh 65
Areal Coverage (Acres) of Selected Seagrass Beds 67
Estimates of Emergent Wetland Acreages (Acres) of Coastal Counties in Florida . 74
Number of Turtle Nests Observed Along Sections of Coast, Summer 1989 83
Water Volume, Average Depth, and Marsh Area of River Deltas 87
11

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Table 24.
Table 25.

Table 26.

Table 27.
Table 28.
Table 29.

Table 30.
Table 31.
Table 32.

Table 33.
Table 34.
Table 35.
Table 36.
Table 37.

Table 38.

Table 39.
Table 40.
Table 41.
Table 42.
Table 43.
Table 44.
Table 45.
Areal Extent (Acres) of Vegetated Wetlands by River System and Year  .
  88
Human Impacts on Selected Texas Barrier Island Regions and a Summary of Current
Acreage (Acres) by Habitat Type	;	   90
Net Changes in Area from Marsh to Open Water in the Neches River Basin,
Texas	   94
Galveston Bay Wetland Habitat Changes, 1956-1979	   95
Landings of Commercial and Recreational Fisheries in Galveston Bay in 1986 .  .   96
Annual Weight of Finfish Landed by Recreational Boat Fishermen from Galveston
Bay during  1984, 1985, and 1986  .		.'...;	   96
Annual Production of Primary Producers in Tampa Bay	  100
Summary of Major Habitat Trends In Acres for the Tampa Bay Region .......  101
Area (Acres) of Various Wetland Habitats for 21 Quadrangles in the Tampa Bay
Region for Three Time Periods	  102
Changes in Habitat Acreages in Sarasota Bay .	 ... ............  .  104
Wetland Acreage Change in Charlotte Harbor from 1945-1982  .............  104
Acres (x 100) of Specific Habitats in the Atchafalaya Basin	  109
Net Areal Change (Acres) and Average Annual Rates of Change of Marsh to
Nonmarsh in Barataria Basin, Louisiana .	  Ill
Marsh Area (Acres) in 1945, 1956, 1969, and 1980 and Rates of Change During
1945-56, 1956-69, and 1969-80 in Barataria Basin Marshes .....  .	  112
Change in Area (Acres) of Habitats in the Calcasieu Basin, Louisiana between 1953
and 1975	 . .	  116
Wetland Losses (Acres) in the Chenier Plain Between 1952 and 1974
Change in Acreage (Acres x 100) in Louisiana Wetlands  .........
                                                  ->
Habitat Acreages in Alabama's Mobile-Tensaw River Delta . ......
Impact of Dredging Activities on Mobile Bay Estuarine Marshes . . .
Estimates of Marsh Area by Type and Geographic Area for Mobile Bay and the
Mobile Delta .	
Summary of Studies Documenting Loss of Coastal Habitats in Gulf States
Selected Wetland Changes (Acres) Along the Gulf Coast	,
116
117
118
121

122
126
128
                                           111

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                                    LIST OF FIGURES
                                                                                      Page
Figure 1. Acreage Percentages of Coastal Emergent Wetlands by State 	   18
Figure 2. Percentage of Specified Habitat Gulf-wide	 .	   19
Figure 3. Impacts on Quality and Acreage of Wetland Habitats in the Gulf of Mexico ....   43
Figure 4. Impacts on Natural-Emerged and Submerged Aquatic Vegetation	   44
Figure 5. Impacts on Bathymetry and Water  Patterns on Wetlands   .........;	   45
Figure 6. Range of Sea Turtles in Gulf Coast States	   77
Figure 7. Range of Selected Endangered or Threatened Bird Species in Gulf Coast States  .   78
Figure 8. Range of Selected Endangered or Threatened Mammals in Gulf Coast States  ...   79
Figure 9. Range of Selected Endangered or Threatened Fish, Reptile, and Amphibians in Gulf
         Coast States	   80
                                            IV

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                     U.S. ENVIRONMENTAL PROTECTION AGENCY
                             GULF OF MEXICO PROGRAM
                       HABITAT DEGRADATION SUBCOMMITTEE
 William L. Ktuczynski
 U.S. Environmental Protection Agency
 Environmental Research Laboratory
 Gulf Breeze, Florida 32561

 Donald F. Bosch
 Center for Environmental and Estuarine
 Studies
 University of Maryland
 Cambridge,  Maryland 21613

 R. Eugene Turner
 Center for Wetland Resources
 Louisiana State University
 Baton Rouge, Louisiana  70803

 Larry Goldman          ,
 U.S. Fish and Wildlife Service
 P.O. Drawer 1190
 Daphne, Alabama 32526

 Kenneth Heck
 Dauphin Island Sea Laboratory
 P.O. Box 369
 Dauphin Island, Alabama 36528

 R. Robin Lewis III
 Lewis Environmental Services
 P.O. Box 20005
 Tampa, Florida  33622-0005

 Kenneth Haddad
 Florida Department of Natural Resources
 100 8th Ave. S.E.
 St. Petersburg, Florida 33701

 Larry Lewis
 Mississippi Bureau of Marine Resources
 2620 W. Beach Boulevard
 Biloxi, Mississippi 39531

 Rex C. Herron
 National Marine Fisheries Service
 Bldg. 1103
 John C. Stennis Space Center
 Stennis Space Center, Mississippi  39529

 Peter Sheridan
 National Marine Fisheries Service
4700 Avenue U
Galveston, Texas 77550

Bill Good
Louisiana Department of Natural Resources
P.O. Box 94396
Baton Rouge, Louisiana  70804
 Paul Montagna
 University of Texas
 Marine Science Institute
 Port Aransas, Texas 78373

 Warren Pulich
 Texas Parks and Wildlife
 4300 Smith School Road
 Austin, Texas 78744

 Robert Rogers             •
 Mineral Management Service
 1201 Elmwood Part Boulevard
 New Orleans, Louisiana 701302

 Bennett Landreneau
 Soil Conservation Service
 3737 Government Street
 Alexandria, Louisiana  71302  ,

 Carl Brown
 U.S. Army Corps of Engineers
 Waterways Experiment Station
 3909 Halls Ferry Road
 Vicksburg, Mississippi  39280

 Brent W. Smith
 U.S. Department of Energy
 900 Commerce Rd.
 New Orleans, Louisiana 70123

 William G. Cibula
 National Aeronautics and Space
 Administration
 John C. Stennis Space Center
 Stennis Space Center, Mississippi
39529
Mary Watzin
U.S. Fish and Wildlife Service Research Unit
University of Vermont
School of Natural Resources
Burlington, Vermont 05405

Mike Evans  (CAC Representative)
1901 Ames Blvd.
Marrero, Louisiana  70072

Dr. Robert Stewart
National Wetland Research Center
1010 Gause Blvd.
Slidell, Louisiana 70458

Mr. Ronald J. Ventola
Chief of Regulatory Functions Branch
New Orleans District
Army Corps  of Engineers
P.O. Box 60267
New Orleans, Louisiana  70160-0267

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                                CONVERSION FACTORS
METRIC
1 meter (m)
1 meter (m)
1 kilometer (km)
1 hectare (ha)
1 square kilometer (km2)
1 square kilometer (km2)
1 kilogram (kg)
1 metric ton (mt)
ENGLISH
39.37 inches (in)
3.281 feet (ft)
0.62 mile (mi)
2.47 acres (ac)
0.3861 square miles (mi2)
247 acres (ac)
2.2046 pounds (Ib)
1.1  ton (t)
                                            VI

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PREFACE

This report was prepared by the Habitat Degradation Subcommittee of the U.S. Environmental
Protection Agency's Gulf of Mexico Program. Subcommittee members supplied pertinent data and
references which were summarized and assembled by the editors of this document. The data and
information contained in this review were obtained by dedicated scientists and resource managers
who were aware of the ecological and social significance of wetlands, seagrasses, and other Gulf
habitats long before their importance was generally recognized. This report is meant to summarize
and highlight their contributions to the knowledge of Gulf of Mexico resources.

The authors appreciate the many useful recommendations given during review of the draft
document. Those recommendations have helped in making this report on habitat losses in the Gulf
of Mexico coastal area as complete a summary as possible. We gratefully acknowledge B. Albrecht,
A. Leskowich, and E. Luna of TRI, Inc. for their assistance in reviewing, organizing, and
summarizing the data used in this report. We also thank the many colleagues who supplied
unpublished data and information, as well as encouragement. We are especially appreciative for the
time and information given by W. White, Texas Bureau of Economic Geology, and W. Longley, Texas
Water Development Board.

This report is not intended to be a complete literature review of all Gulf of Mexico habitats.
Rather, it is a convenient summary of available information on the acreage of saline coastal emergent
and submerged vegetated habitats. It is hoped that future reports will address the status and trends
of other Gulf of Mexico coastal and nearshore habitats, such as swamps, pine flatwoods, savannahs,
beaches and dunes, tidal flats, soft bottoms, hard bottoms, and coral reefs. The Bibliography
contains many references not cited in the text and are included for those who wish to pursue a topic
in more detail than given herein.

Finally, the authors wish to caution the readers that it is not advisable to compare acreages
given in different inventories summarized in this report since different definitions, baselines, and
criteria were used in preparation of each inventory. However, in Case Histories we have assembled
historical data for selected estuarine systems which were analyzed by the same author for the purpose
of identifying trends of habitat acreage.
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EXECUTIVE SUMMARY

The purpose of this report is to present a comprehensive summary of the current status and
historical trends of saline vegetated habitats of the coastal region of the Gulf of Mexico, U.S.A. The
inland boundary of this survey is based upon the U.S. Fish and Wildlife Service's (FWS) delineation
of estuarine habitats and is generally an imaginary line across rivers, bays, sounds and the like where
the ocean derived salts measure less than 0.5 ppt during periods of low flow and where there is little
measurable tidal influence. The seaward limit of the survey is generally restricted to offshore areas
of continually diluted seawater. ,

Data bases for habitat types within the coastal area of the Gulf were found to be dissimilar.
Thus, it was not possible to discuss all habitat types in the same amount of detail. Most of the
acreage inventories presented herein are for marsh habitats; however, available published information
is summarized for seagrass and mangrove habitats.
I
Because of dissimilarities of definitions, baselines, and other factors, it is not advisable to
compare acreages of habitat type given in different inventories. However, historical information
given in Case Histories for selected waterbodies are compared when data from the same author was
available for different time periods.

Inventories of Coastal Habitats and Living Resources

Wetlands are highly productive habitats that are of great value to society and the environment.
Wetlands are defined as: "Those areas which are inundated or saturated by surface or groundwater
at a frequency and duration sufficient to support, and that under normal circumstances do support,
a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally
include swamps, marshes, bogs, and similar areas" (Federal Interagency Committee for Wetland
Delineation, 1989). Coastal wetlands of the Gulf of Mexico are of special interest because of their
recognized importance in maintaining the production of the rich Gulf fisheries resources.

A review of historical inventories indicates that acreage of all emergent and submerged
vegetated wetland communities in the nation is decreasing. Overall, approximately 54% of the
original 215 million ac (87 x 106ha) which were present at the founding of the country have been
lost. There were approximately 108 million ac (44 x 106ha) of wetlands in the 1950's and 99 million
ac (40 x 106ha) in the 1970's, a loss of over 9 million ac (3.6 x 106 ha). The majority of historic
losses were due primarily to agricultural conversion of bottomland hardwoods and other wetland
Vlll

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     types and development of palustrine and estuarine wetlands.  This rapid loss rate, in part, led to
     increased federal and state regulatory programs governing the conversion of wetlands.

          The recently completed Gulf-wide inventory, prepared by the National Oceanographic and
     Atmospheric Administration (NOAA), is based on FWS National Wetland Inventory maps prepared
     from 1972 to 1984 aerial  photographs.  The'NOAA report summarizes acreage of coastal wetland
     types by counties and by selected estuarine drainage areas. Because recent national trends indicate
     that the amounts of most wetland types are still declining,  the acreages presented in the NOAA
     report may be greater than the actual current acreage of coastal  wetlands.  The following table
     summarizes the most recent information on the current status of five wetland categories in Gulf coast
     states as calculated from NOAA data:
Totals (Acres) of Selected Wetlands by State for the Gulf of Mexico (from NOAA, 1991)1'2


State
Texas
Louisiana
Mississippi
Alabama
Florida


; Salt Marsh
432,000
1,722,800
58,800
25,500
257,200

Fresh Marsh
(Tidal)
22,500
65,000
_3
100
9,800
Forested
Scrub-Shrub
(Estuarine)
2,600
10,200
900
2,800
613,700
Forested
Scrub-Shrub
(Tidal Fresh)
7,400
4,800
-
2,000
18,400

Tidal
Flats
275,100
31,800
2,300
4,100
192,900


Total
739,600
1,834,600
62,000
34,500
1,092,000

Percentage
of Total
20 .
49
2
0
29
TOTALS
2,496,300
97,400
630,200
32,600
506,200  3,762,700
1 Acreage originally reported as acres x 100
2 Calculations based on FWS wetland inventory maps
3 None recorded                   ,
          Seagrass habitat was not included in the NOAA survey.  Of the five major coastal wetland
      habitats included, .66% of the acreage was salt marsh,  17% forested scrub-shrub, 13% tidal flats, 3%
      tidal fresh marsh, and 1% forested. The distribution of these habitats is not equal across the Gulf
      states.  Louisiana contains most of the Gulfs salt marshes with 69%,  followed  by  Texas (17%),
      Florida (10%), Mississippi (2%), and Alabama (1%). Texas contains 54% of the tidal flats and Florida
      has 97% of the estuarine forested scrub-shrub habitats (mostly mangroves).
                                                  IX

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Other surveys have estimated acreage of seagrass meadows. There are an estimated 800,000 ac
(323,887 ha) of seagrasses within Gulf estuaries, and 95% of these are found in Florida and Texas.
Large meadows of seagrass are located near shore along the west coast of Florida; 2,123 mi2 (5,500
ha) of beds are located within the boundaries of the Everglades National Park in Florida Bay.
Seagrass meadows support diverse flora and fauna and are important nursery areas which provide
both cover and food for many species of fish which are harvested commercially and recreationally.
Unfortunately, human activities have resulted in extensive historic direct losses of seagrasses. Also,
suspended particulate materials from dredging and other activities can block sunlight from
seagrasses, and interfere with their growth and reproduction.

Mangrove forests occur mainly along Florida's coasts. Estimates of the total area of mangroves
in Florida range from 430,000 to 650,000 ac (174,000 to 263,000 ha). Mangrove forests provide
important habitats for young fish and other species and their elimination can result in a loss in
recruitment of juveniles. Several human activities, including ditching or impounding for mosquito
control, reduction of fresh-water input, and clearing and filling, have degraded the quantity and
quality of mangrove habitats.

Wetlands and other coastal communities are important habitats for many threatened or
endangered plants and animals. Marine turtles such as Kemp's Ridley, Hawksbill, Leatherback,
Green, and Loggerhead, as well as other species of endangered or threatened vertebrates, are found
along the Gulf coast. Gulf coastal habitats also provide important sites for bird rookeries.

Functions and Values of Wetlands
Society has been slow in recognizing the functional values of wetlands. Historically, wetland
habitats have been treated as wastelands. Alternate "productive" uses of wetlands have disrupted the
natural functions of many wetland ecosystems. Wetlands provide many important ecological and
societal benefits. They are important habitats for a variety of plants and animals. Many species,
including threatened and endangered ones, are dependent upon wetlands for food, protection from
predators, resting areas, reproductive material or sites, molting grounds, and other requirements of
life. Wetlands act as natural filters which remove organic pollutants, excess nutrients, and suspended
particulates from water as it flows from uplands to the sea. Wetlands restrict the flow of flood
waters and also serve as natural barriers that temper the effects of water surges from episodic events,
such as hurricanes and other storms. They also may lessen wind damage to inland areas. Wetlands
contribute to detrital food webs and are an important link in nutrient processing and cycling.
Finally, wetland communities are aesthetically, pleasing and are natural classrooms.

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Estuaries and fringing wetlands provide critical habitats for many species of sport and
commercial fishes. Estimates vary, but as many as 95% of commercial fish landed and 85% of the
sport catch in the Gulf of Mexico spend at least a portion of their life in estuarine and wetland
habitats. The production of waterfowl and other wildlife, such as fur-bearing mammals, is also
determined by the abundance and quality of wetlands.

Often the values of natural systems are viewed in terms of the dollar value of the tangible and
intangible benefits those systems provide. It is difficult to accurately quantify all of the benefits that
wetlands provide to society. However, economic models, based upon the link between wetlands and
commercial and sport fisheries, have quantified the value of specific wetland types. Values derived
from these studies vary from approximately $1,000 to $82,000 per acre. The wide range of values
reflects the disparity and accuracy of economic theories and estimates, as well as the variance of
wetland types.

Quality of Wetlands

The quality of Gulf wetland habitats has been severely reduced through natural processes, such
as subsidence, erosion, rising sea level, and by human activities, including construction of canals and
channels, dredging, spoil disposal, draining, and filling. Subsidence is the fate of delta marshes
where natural sediment deposition is precluded through construction of dams and other diversions.
These lands can become compacted and sink beneath the water. Currents and surges from hurricanes
and storms can accelerate erosion of sediment and other substrate, resulting in deterioration of
wetland habitats. Sea level rise can hasten wetland subsidence and result in more open water acreage.

Construction and maintenance of canals has adversely impacted wetlands, particularly in coastal
Louisiana. Channels convert emergent wetlands into open water and cause erosion of the remaining
marsh. Saltwater intrusion brought about by altered circulation due to channelization has caused.
deterioration of large areas of coastal wetlands.

Historically, it was common practice in coastal areas to excavate and/or fill wetlands to create
upland for real estate development. Material excavated from the bottom of adjacent waters or
imported fill material was placed on submerged lands along the shoreline or on top of emergent
wetlands to create uplands. Often, the fill material was contained or stabilized by bulkheads. In
addition to direct loss of habitat, this process often resulted in high concentrations of suspended
particulates and detrimental impacts to submerged plant communities in adjacent areas due to
reduced light conditions. Also, changes in texture, particle size, depth and other physical/chemical
changes .resulting from dredging hampered recolonization by benthic flora and fauna.
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One indication of the quality of estuarine habitats is the quality of indigenous shellfish.
Shellfish waters are classified for the commercial harvest of oysters, clams, and mussels based upon
i
public health concerns. Shellfish obtain nourishment by filtering large volumes of water and can
bioconcentrate pollutants which are found in low concentrations in the water. Humans can ingest
these pollutants, which include chemicals, bacteria, and other pathogens, by eating poorly prepared
or raw shellfish meats. Therefore, the harvest of shellfish is strictly regulated and not permitted in
waters which contain certain levels of bacteria and other pollutants.

Shellfish waters are classified by states and by the National Shellfish Sanitation Program (NSSP)
guidelines. This classification reflects concentrations of pollutants, pollution sources, and
concentration of fecal coliform bacteria. Waters are classified as approved, conditionally approved,
restricted, or prohibited. A survey by NOAA in 1987 indicated that approximately 42% of waters
suitable for raising shellfish in the Gulf of Mexico were approved for harvesting. The remaining
•acreage was contaminated sufficiently to result periodic closure or prohibition to shellfish harvesting.

Case Histories

Several detailed case histories are presented. These studies describe the modifications to habitats
which have occurred in specific areas along the Gulf coast.

More than 70% of the total wetland loss from seven Texas river deltas (Colorado, Neches,
Guadalupe, Lavaca, Trinity, Neches, and San Jacinto) from 1930 to 1980 occurred along the San
Jacinto and Neches Rivers (White and Calnan, 1990). Major factors responsible for these losses
include a rise in water level due to human-induced subsidence, natural compactional subsidence,
global sea-level rise, and reduction of movement of sediment to marshes due to reservoir
development in river drainage basins, channelization, and disposal of spoil on natural levees. The
general trend in deltaic wetlands along the Texas coast is conversion of wetlands to open water and
barren flats.

The impacts of human activities on habitats in Tampa Bay, Sarasota Bay, and Charlotte
Harbor, Florida are well documented. Channel deepening, maintenance dredging, and dredging and
filling to create uplands, have resulted in the loss of 44% of the original (100-year study) wetlands
bordering Tampa Bay. In Sarasota Bay, changes in wetland habitat acres from 1948 to 1987 include
loss.es of 35% of its seagrass beds, 45% of mangrove swamps, 85% of tidal marshes, and an increase
of 16% of oyster beds. Wetland changes in Charlotte Harbor from 1945 to 1982 include losses of 29%
of its seagrasses, 51% of salt marshes, 39% of oyster reefs, and an increase of 10% in mangroves.
Several studies conclude that long-term effects of the release of fine sediment into the water column
xn

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from dredging and filling may be even more damaging to plant communities than the initial habitat
destruction.

In the Mississippi River Deltaic Plain, the major habitat issues include loss of salt marsh, salt
water intrusion, and maintenance of habitat and water quality. In Louisiana, a significant change
in acreage in coastal wetlands occurred between 1956 and 1978, when approximately 51% of the
state's emergent marsh and 59% of forested wetlands were lost. During that time period, there was
a concurrent 272% increase in acreage used for disposal of dredged material. Other studies have
shown that approximately 34% of Louisiana marsh was changed to non-marsh from 1945 to 1980,
and that currently there is a net wetland loss of approximately 39 mi2 (101 km2) annually in coastal
Louisiana. Barrier island retreat in Louisiana is occurring at rates as high as 160 ac (65 ha) per year.

A study in Mobile Bay, Alabama revealed that emergent marsh habitat declined by more than
10,000 ac (4,000 ha), or 35%, between 1955 and 1979. Half of this loss resulted from industrial,
commercial, and residential development; other losses were the result of erosion and/or subsidence.
Another survey described a loss of 50% or more of submerged aquatic vegetation. The most
significant impacts noted in these studies were the direct and indirect effect of dredging.

A decline of the area covered by seagrass and a decline of seagrass species has occurred in
Mississippi Sound. Seagrass acreage in 1975 was approximately 60% of that found in 1969, and losses
are continuing. Hurricane damage and seagrass destruction by fresh water discharged through a
spillway account for approximately half of the loss. The causes of the remainder of the losses are
undetermined. The seagrass beds remaining in Mississippi Sound are composed largely of Halodule
wrightii and in this species leaf abundance is reduced compared to historic levels.

, Conclusions

• The Gulf coastal zone is characterized by a great diversity of habitats and natural resources,
as well as industrial and recreational potential. The coastal area is richly endowed with
productive wetland habitats whose ecological functions enhance viable wildlife and fishery
resources of the Gulf. Wetland systems are in natural biogeochemical balance with
contiguous terrestrial, freshwater, and marine systems from which the wetlands both receive
and contribute biomass, nutrients, and other essential ingredients. The natural balance can
be adversely impacted by society and nature and these impacts can change, irreversibly, the
quantity and/or the character of the habitat. For example, when accretion of sediments by
marshland is exceeded by subsidence, the result is a loss in marshland and an increase in
open water.
xm

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•   Although it is difficult and sometimes impossible to precisely compare acreages of wetlands
    at different time intervals, available comparisons indicate a major and continuing loss of
    emergent marsh, mangrove, and seagrass habitats along the Gulf coast.  This loss often is
    due to a coupling of natural forces and human activities.

•   Although economic evaluation of wetlands is still developmental, a recent study has placed
    the value of marsh in south Florida, based on sport and commercial fisheries landings alone,
    to be equivalent to some estimates of the commercial value of the land for development.

•   In many instances, wetland habitats along the Gulf coast continue to be besieged by human
    activities such as dredging and filling for construction of canals, marinas, port facilities, real
    estate development, and conversion to other uses.  Natural phenomena such as subsidence,
    sea level rise, and erosion are  also adversely impacting wetlands.  The primary causes of
    diminishing quality and losses of coastal emergent wetlands vary from state to state and
    include  subsidence due to extraction of oil, gas, and fresh water in Texas; alterations of
    hydrodynamic flow due to construction of navigation channels, as well as subsidence, in
    Louisiana; and dredge and fill operations in Mississippi, Alabama, and Florida.

•   Closure  of vast areas pf  shellfish harvest waters is common to all  Gulf states and  is
    indicative of deterioration of water quality.

•   Submerged vegetated communities in all Gulf  coastal waters are susceptible to adverse
    effects of direct filling  through deposition of dredged material and indirectly  from the
    production of suspended material in the water column that blocks the sunlight necessary for
    growth and reproduction.  Excess nutrients from sewage treatment plant discharges, septic
    tank systems, and drainage  from agricultural fields contribute to  seagrass declines by
    stimulating growth of periphyton on the plants and phytoplankton in the waters over the
    grass beds.

•   The loss of quantity and  quality of wetlands has slowed since the late 1970's due to passage
    and enforcement of federal and state laws and regulations.  Also, the ecological and societal
    functions of wetlands are becoming better known to resource  managers and to a more
    interested and active public. Better informed managers and public awareness have made
    a positive difference in management decisions concerning the disposition of  wetland
    habitats.
                                       xiv

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Interest in habitat management and research continues to grow.  Many wetlands research
and demonstration projects are underway or about to begin.  For example, the U.S. FWS is
digitizing information on wetland acreages in Gulf coastal states (some of the preliminary
data are presented in this report), NOAA continues to collect data in the Status and Trends
Program, EPA has initiated a monitoring program  in near coastal waters and estuaries
(Ecological Monitoring and Assessment Program), and Florida and Texas will soon publish
Up_to-date wetland acreage  data.  The U.S. Army Corps of Engineers is designing and
testing several freshwater diversion projects to improve the condition of wetland habitats
along the lower Mississippi River.
                                    xv

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Introduction

' The purpose of this report is to summarize the current status and historical trends in quality
and quantity of saline coastal wetland and seagrass habitats of the Gulf of Mexico. The paper is
organized into the following sections: Inventories of Coastal Habitats, Functions and Values of
Coastal Habitats, Quality of Coastal Habitats, Living Resources, Case Histories, and Conclusions.
The boundaries of emergent coastal wetlands are based on the delineation of estuarine boundaries
by Cowardin et al. (1979) and include areas: 1) upstream and landward where ocean-derived salts
measure less than 0.5 ppt during periods of low flow, or where there is a significant tidal influence;
2) an imaginary line closing the mouth of a river, bay, or sound; and 3) to the seaward limit of
wetland emergent vegetation where it is not included in 2). This system also includes offshore areas
of continually diluted seawater.

Ecological habitats along the Gulf of Mexico coast are many and varied. Habitats discussed
in this document are limited to the coastal plain and are generally delineated by the upper reaches
of tidal action and include emergent herbaceous marshes, mangrove forests, and seagrass meadows.
The intention of this document is not to summarize all available information on these habitats, but
rather to summarize data given in surveys of historical and current acreages. Additional references
are included in the Bibliography for those interested in pursuing other topics in more detail than
presented in this report.

Data presented in published and unpublished surveys of habitat acreage are summarized and
discussed. Many surveys of habitat quantity have been made for different purposes and the
definitions of wetland types, baselines, and interpretation of boundaries may differ between surveys.
Thus, it is not advisable to directly compare acreages of habitats measured at different times by
different authors. We have summarized trends in habitat change in Case Histories for selected
estuaries where measurements of habitat acreages were made using the same method for different
time periods specifically for the purpose of calculating changes in habitat extent.

The function of coastal ecosystems is dependent upon the quantity and quality of coastal
habitats. Thus, the amount of habitats lost may be a good indicator of estuarine "health." Other
indicators of the health of coastal areas include the status of shellfish resources for human
consumption and endangered species and their habitat. For this reason, summaries of available
information on shellfish harvesting and endangered species are presented.

The Gulf of Mexico is bordered by 207 estuaries (Thayer and Ustach, 1981). The total open-
water area of Gulf estuaries at mean high water is approximately 7.9 x 106ac (3:2 x 106ha) with a
volume of approximately 57.9 x 106acre-ft (Lindall and Saloman, 1977. The estuarine acreage is not
\
1

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evenly distributed among Gulf states. Louisiana contains 43%, Florida 26%, Texas 19%, Mississippi
6%, and Alabama 5% of the estuarine acreage. The Gulf coastal region is dominated by warm
subtropical waters and generally small tidal ranges. From Apalachee Bay, Florida, southward tides
range from 1.97 to 3.94 ft (0.6 to 1.2 m), while to the west, tidal amplitude generally is < 2 ft (0.6 m)
(Brooks, 1973; Christmas, 1973; Diener, 1975).

The shoreline of the Gulf coast of the U.S.A. is 15,500 mi (25,000 km) long and includes many
diverse wetland habitats including tidal marshes, mangroves, and submerged seagrass beds. Coastal
marshes and mangroves forests form the interface between marine and terrestrial habitats, while
seagrass beds interface between emergent vegetation and unvegetated estuarine and coastal bottoms.
The geography of these habitats vary throughout this broad zone. In some areas fringing wetlands
occur as narrow bands, while in other areas marshes are very broad and cover large areas.
i
Coastal Gulf wetland habitats can consist of either monotypic stands or diverse plant
communities. Wetlands are transitional zones between terrestrial and aquatic environments and there
is a wide variety of wetland habitats. Coastal, estuarine wetlands occur in areas of reduced salinity
and are transitional zones between fresh and salt water habitats. "Wetlands" is used as a collective
term for habitats such as bogs, marshes, and swamps. A more scientific definition of wetlands has
been offered by Cowardin et al. (1979): "Lands transitional between terrestrial systems where the
water table is at or near the surf ace; or the land is covered by shallow water. Wetlands must have one
or more of the following attributes: 1) at least periodically, the land supports predominately
hydrophytes; 2) the substrate is predominately undrained hydric soil; 3) the substrate is nonsoil and
is saturated with water or covered with shallow water during the growing season." This definition
includes submerged aquatic vegetation such as the productive seagrass beds found in coastal waters
of the Gulf.
The U.S. Army Corps of Engineers (COE) and the U.S. Environmental Protection Agency
(EPA) are responsible for making jurisdictional determinations of wetlands for regulatory purposes
and have developed the following definition of wetlands: "Those areas that are inundated or
saturated by surface or groundwater at a frequency and duration sufficient to support, and that under
normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated
soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas." A
standardized methodology for delineating wetland limits has been developed and includes this
definition of wetlands (Federal Interagency Committee for Wetland Delineation, 1989). This method
requires that hydric soils, hydrology, and prevalence of wetland plants be present at normal sites.
Proposed changes to this methodology are currently under review.

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Wetlands are highly productive habitats and have great value to people. The acreage of wetland
habitats has been decreasing at an alarming rate for the past 40 years. In the past, wetlands were
often viewed as wastelands to be converted to farmland or residential and industrial sites. More
recently, the value of wetlands to coastal ecosystems and to human well-being has become
recognized. Some now see wetlands as "wonderlands" as opposed to "wastelands" (US. EPA, 1988a).
The gradual development of this positive attitude toward wetlands is in part due to an increased
understanding of their role in general ecological processes and a better understanding and
quantification of the tangible value of wetlands to society.

Wetlands provide shelter for many species of plants and animals which inhabit these unique
areas. For example, coastal emergent wetlands, including salt marshes and mangrove forests, furnish
protective cover for the food organisms needed by many larger animals. Coastal wetlands contribute
organic material to the detrital food web and are integral to the processing and flow of nutrients.
Wetlands are natural filters and remove organic pollutants, excess nutrients, and suspended
particulates from water as it flows from the terrestrial environment to the sea. They also serve as
natural barriers that temper the effects of water surges from episodic events, such as hurricanes and
other storms, and may lessen wind damage to inland areas.

Wetlands contribute to human activities in many ways. For example, they provide important
nursery habitat for many sport and commercial fish species. Estimates vary, but as much as 95% of
the weight of commercial fish landed and 85% of the weight of the sport catch in the Gulf of Mexico
comes from fish that spend at least a portion of their life in coastal wetland and estuarine habitats
(Thayer and Ustach, 1981; Lindall and Thayer, 1982).

During the past few decades the Gulf estuaries have begun to show signs of increased
deterioration of environmental quality. Serious deterioration is becoming evident in many locations.
Loss of quality and acreage is occurring for marshes, seagrass beds, and mangroves, as well as in hard
substrates, such as shellfish beds and coral habitats. Impacts are directly linked to increased human
activities within estuarine watersheds (NOAA, 1990c).

Wetlands can be adversely impacted by both natural and human activities. Natural causes that
result in loss of wetlands include subsidence and impact from hurricanes and other storm events.
Subsidence is the natural fate of delta areas which no longer receive sediments from rivers or flood
waters. Human activities which interrupt the flow of water to wetlands and deprive them of the
required sediment can exacerbate the rate of subsidence. Hurricanes and other strong storm surges
can flood freshwater marshes with saltwater which kills salt intolerant plants. Rising sea levels can
accelerate the loss of wetlands by converting them to open water areas. Human activities that have
been especially harmful to wetland habitats include: draining for crop and timber production;

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draining or impounding for mosquito control; dredging for construction and maintenance of
navigation and access channels, flood protection, or development; and discharging of sewage, toxic
effluents, and other wastes. Increased state and federal regulatory control has begun to slow the rate
of loss of several wetland types. : For example, the passage of the "swampbuster" provisions of the
1985 Food Securities Act has slowed the rate of conversion of productive swamp wetlands to
agriculture lands. •
^^
The Gulf of Mexico is one of the fastest growing regions in the nation. The population of
the Gulf coast increased 33% between 1970 and 1980, and the population is projected to increase by
144% between 1960 and 2010 (Culliton et al., 1990). Concurrent with population growth has been
a decline in environmental quality. Increased population has resulted in increased pressure for
wetland development and in increased discharges of domestic and industrial wastes into coastal
waters.

A good indicator of the ecological health of an estuarine system is the ability to harvest shellfish
for human consumption. Approximately 30% of harvestable shellfish waters in the Gulf were closed
to harvesting in 1985 (NOAA, 1988c). The closure of shellfish waters for harvesting due to excess
colif orm bacteria concentrations is one indication that society's pollution has degraded estuarine and
wetland habitats. Recently, the occurrence of persistent marine debris such as plastics on coastal
beaches has been a concern because this unsightly material accumulates and may have adverse effects
on animals through ingestion or entanglement. Also, the aesthetic delight of a natural experience is
degraded by the prevalence of human refuse which may be indicative of our disregard for natural
habitats.

It is often difficult to precisely compare acreages of wetlands at one location measured at
different time intervals because of possible differences in wetland classification, tidal and moisture
conditions, and wetland mapping criteria. However, it has been documented that wetlands are
continuing to be lost nationally as well as regionally in the Gulf of Mexico. Approximately 97
million ac (39 x 106 ha) of wetlands remain of the original 215 million ac (87 x 106 ha) in the
contiguous U.S. (Tiner, 1984). According to Prayer et al. (1983), over 9 million ac (3.6 x 106ha) of
the nation's wetlands were lost from the 1950's to the 1970's. Most of this decrease was in inland
areas, but coastal habitats also experienced marked declines. Realization of these losses prompted
Congress to include Section 404 in the 1972 reauthorization of the Federal Water Pollution Control
Act. Section 404 requires a federal permit for dredging and filling of waters of the United States
including wetlands. The history of the Section 404 program has been discussed by Lieberman (1984),
Want (1984), Nagel (1985), Anadromous Fish Law Memo (1988), Brady (1990), and others. All agree
that regardless of the federal regulatory program, wetlands continue to be lost by natural and human
causes. This fact prompted the convening of the National Wetlands Policy Forum by the

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Conservation Foundation at the request of EPA in 1987 which adopted as its interim goal to "achieve
no overall net loss of the nation's remaining wetland base" (National Wetlands Policy Forum, 1988).

Recent wetland losses in some areas remain great. For example, Day and Craig (1981) estimated
that 32,000 ac (SOmi2) (13,000 ha) of wetlands were being lost annually in coastal Louisiana. Coastal
Louisiana wetland losses were recently estimated to be 31 mi2 per year (Dunbar et al., 1990). Similar
losses during this period have been documented in all Gulf coast states, particularly in Galveston
Bay, Texas; delta habitats in Louisiana; the Mississippi Sound; Mobile Bay, Alabama; and Tampa and
Sarasota Bays in Florida. Detailed analyses of historical and continuing wetland losses of these areas
are summarized in Case Histories of this report.

The value of wetlands depends upon the beholder's perspective. Some view wetlands as
potential sites for residential development, some as havens for fish and wildlife, and others as
cultivatable farmland or prospecting grounds for oil and gas production. Because of the many
competing uses of wetlands, it has become commonplace to attempt to quantify the market value of
wetland acreage. This is often difficult because there are many kinds of habitats which produce
varying amounts of tangible and intangible products. Several attempts have been made to place a
monetary value on the tangible services provided by wetland habitats (e.g., fisheries productivity).
However, these habitats are an integral part of the coastal ecosystem and provide many intangible
goods and services to society, such as aesthetic values, teaching tools, and nutrient cycling. The
monetary values of these intangible goods and services are very difficult to quantify.

Some progress has been made in estimating a market value of the capacity of wetlands to
provide vital habitat for fishery organisms. Several biologists and economists have suggested a
relationship between yields of commercial and sport fisheries and acreage of wetland habitats which
are available to fish and shellfish (Turner, 1977; Deegan et al., 1986). Based on these relationships,
economic models have been developed to establish the value of specific wetlands; estimated values
have ranged from less than $1,000 to $82,000 per acre (Bell, 1989; Foster, 1978; Gosselink et al.,
1974).

The nutrient-rich and highly productive emergent vegetated wetlands, such as marshes and
mangroves, submerged aquatic habitats, such as seagrasses, coral reefs, and other live bottoms, and
mud and sand flats provide important habitat for the living resources, including numerous
endangered species of the Gulf of Mexico. Probably one of the most important values of wetlands
is their use by many estuarine and marine animals for spawning, rearing, feeding, migration, and
protection from predators. Thus, populations of these organisms can be limited by the quality and
quantity of these habitats.

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     The coastal wetlands of the Gulf of Mexico are of special interest because the Gulf is an
exceptionally productive sea that annually yields nearly 2 billion pounds (900,000 mt) of fish  and
shellfish and contains five of the top seven commercial fishery ports in the nation by weight (NOAA,
1990). The Gulf is one of the few areas of the U.S. Exclusive Economic Zone that possesses large
quantities of unexploited fishery-resources.  The Gulf is  well known for its  coastal estuaries,
wetlands, and barrier  islands that  provide important habitat for large populations  of wildlife,
including waterfowl, shore birds, and colonial nesting birds. For example, the Gulf provides critical
habitat for 75% of the migratory waterfowl traversing the United States. The extensive emergent
herbaceous coastal wetlands which remain in the Gulf make up about half of the Nation's remaining
total wetland area (U.S. EPA, 1988c).

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                                  Inventories of Coastal Habitats

       The purpose of this section is to provide a summary of major inventories of coastal habitats.
  The reader is cautioned not to attempt to  compare data between inventories since baselines and
  definitions are not consistent among  them.  All historical surveys document that  the acreage of
  wetlands in the Nation, particularly the Gulf of Mexico, decreased dramatically between the 1950's
  and 1970's. According to Prayer et al. (1983), the total acreage of wetlands and deep-water habitat
  nationwide was 179.5 million ac (72 x 106ha) in the  1950's and 171.9 million ac (69.6 x  106ha) in
  the 1970's, a loss of 7.6 million ac (3.1 x 106ha) (Table 1). There were 108.1 million ac (43.8 x 106
  ha) of wetlands in the 1950's and 99.0 million ac (40.1 x 106ha) in the 1970's, a loss of over 9 million
  ac (3.6 x 106 ha). The majority of this loss was in palustrine freshwater and estuarine wetlands. In
  general, these data are useful only at the national level because of difficulties in comparing acreage
  figures  estimated at different  times.  Also, Prayer  et al. did  not estimate  acreage of seagrass
  communities.
Table 1. Wetlands Acreage (Acres) Changes from 1950's to 1970's (From Prayer et al., 1983)*


Marine
Intertidal


Estuarine
Subtidal

Estuarine
Intertidal
Non-veg.

Estuarine
Intertidal
Emergent
Estuarine
Intertidal
Forested
Scrub/shrub
Estimated Acreage
in 1970's       '    78,400 (14.0)2  14,967,700 (1.5)   746,500 (9.8)  3,922,800 (4.3)
Estimated Acreage
lost or gained in
1950's to 1970's    -4,000 (57.5)   +200,200 (14.9)      +5,400 (*)3  -353,200 (8.3)
573,000 (14.4)


-19,100(93.2)
1 Original acreage presented as acres x 1000
2 Standard error (percentage of the entry)
3 Standard error of estimate is equal to or larger than estimate
        Tiner (1984) also reviewed the losses of Wetlands from the 1950's to the 1970's and found that
   the greatest wetland losses nationally during that period occurred along the Gulf coast, particularly
   in Louisiana, Florida, and Texas. Most of Louisiana's losses were attributed to submergence by
   coastal 'waters, while dredge and fill  and residential development in coastal areas were most
   significant in Florida and Texas.

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Tiner divided the major causes of wetland loss and degradation into three categories: direct
human effects, indirect human effects, and natural effects. Direct human effects included drainage
for crop production, dredging and stream channelization, filling, construction of dikes, dams, levees,
and seawalls, discharges of pollutants and other materials, and mining of wetland soils. Indirect
human causes included sediment diversion by dams, deep channels, and other means, hydrologic
alterations by canals, levees, and spoilbanks, and subsidence due to extraction of materials (ground
water, oil, gas, etc.). Natural threats included subsidence, droughts, hurricanes and other episodic
events, and grazing by nutria and muskrats. '

A nationwide compilation of existing coastal wetlands data was conducted by the National
Oceanic and Atmospheric Administration (NOAA) (Alexander et al., 1986) and was based on U.S.
Fish and Wildlife Service (FWS) data and other existing sources of information. NOAA did not use
the U.S. FWS classification system because some data were obtained from states, and many states had
their own classification systems.

These data, gathered at different times between 1954 and 1980, indicate the presence of over
11 million ac (44,534 km2) of wetlands along the coastal United States, of which 5,184,000 ac (20,988
kmr) are located in the Gulf of Mexico. Emergent wetland acreage, consolidated under three
categories, is given in Table 2.
Table 2. Wetland Acreage (Acres) in the Gulf of Mexico (from Alexander et aIM 1986)1
State
Florida
Alabama
Mississippi
Louisiana
Texas
Subtotal
Salt Marsh
431,300
14,600
64,000
1,748,600
390,400
2,648,900
Fresh Marsh
77,500
10,600
4,000
688,800
896,500
1,676,500
Forested
970,700
151,300
76,000
437,200
40,300
1,675,500
Total
1,479,500
176,500
144,000
2,874,600
509,400
5,184,000
1 Aerial photography dates:
FL - 1972-1976
AL = 1976-1978
MS - 1979-1980
LA « 1976-1978
TX = 1950-1951

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Alexander et al. (1986) also reported these data by county. The manner in which each state
delineated wetlands and its classification methodology are found in an appendix of that report. A
fundamental obstacle to consolidating these data is the lack of a unified system of classification and
quantification. Another problem is that wetlands conform to drainage basins, not political
boundaries. Also, acreages of seagrasses and tidal flats were not included in this survey.

The most recent Gulf-wide wetland inventory was prepared by NOAA (1991) which lists
acreage and habitat types of coastal wetlands for the five Gulf coast states. The most recent NOAA
report also summarizes coastal wetland acreage by estuarine drainage area (EDA) and by county.
NOAA's research included a review of existing data on the areal extent and distribution of coastal
wetlands, but much of this information was found to be incomplete or outdated. NOAA then
evaluated an alternative source of information, the National Wetland Inventory (NWI) mapping
program of FWS. The NWI program has summarized scientific information on the extent of the
Nation's wetlands through creation of detailed maps and research on historical status and trends.
The maps are developed from aerial photography and are based on 1:24,000 scale U.S. Geological
Survey (USGS) maps. The NWI maps were quantified by NOAA using a grid sampling technique
which provided a time and cost effective alternative to standard digitizing techniques. Methods and
statistical reliability of this technique are given in the NOAA report.

In all, 56.2 million ac (227,530 km2) were sampled by NOAA. Of this, 24% or 13.7 million ac
(55,466 km2) were identified as wetlands. Four major wetland habitat types are listed. The largest
category is forested wetlands (8,100,000 ac; 32,794 km2; 59% of total), followed by fresh marsh
(2,600,000 ac; 10,526 km2; 19%), salt marsh (2,500,000 ac; 10,121 km2; 18%), and tidal flats (500,000
ac; 2,024 km2; 4%). Open water and uplands are included as nonwetland habitat types in this survey.

The major habitat types are further subdivided into wetland subgroupings and nonwetlands and
include: salt marsh - brackish, high, low, unspecified; fresh marsh - nontidal, tidal, unspecified;
forested and shrub-scrub - estuarine, nontidal fresh, tidal fresh, unspecified fresh; tidal flats; open
water - fresh and nonfresh; and uplands. Definitions of these habitat types and common plant
communities are given in Table 3.

The dates of aerial photography for the maps used in the NOAA study ranged from 1972 to
1984, with 28% taken in 1979 and 42% taken after 1980. Because of the date of the photographs and
the fact that national trends indicate that the amounts of most wetland types are still declining
(Prayer et al., 1983), wetlands statistics presented by NOAA may over estimate the actual current
amount of coastal wetlands.

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Table 3.  Coastal Wetlands Classification for the Gulf of Mexico (from NOAA, 1991)
NOAA
 FWS
 Common Plant Community
Salt Marsh

     Brackish




     High




     Low



     Unspecified
Estuarine intertidal emergent
regularly and irregularly flooded
salinity >0.5o/00and <30o/00
Estuarine intertidal emergent
irregularly flooded salinity >30°/00
Estuarine intertidal emergent
regularly flooded or irregularly
exposed salinity >300/00

Estuarine intertidal emergent
 black needlerush (Juncus
 roemerianus). salt hay grass
 (Spartina patens), salt grass
 (Distichlis spicata)

 black needlerush (JL
 roemerianus). salt hay grass
 (S.. patens), salt grass (EL
 spicata)

 smooth cordgrass (S..
 alterniflora)
see "brackish," "high," and "low"
Fresh Marsh

     Tidal
     Unspecified
Lacustrine littoral emergent tidal
Palustrine emergent tidal
Riverine tidal or lower perennial
emergent tidal

Lacustrine littoral emergent

Palustrine emergent
Riverine tidal or lower perennial
spike-rush (Eleocharis spp.)
three-square rush (Scirpus
americanus)
see "tidal"
Forested and scrub-shrub

     Estuarine
     Tidal fresh
Estuarine intertidal forested or
scrubrshrub
Palustrine forested or scrub-shrub
tidal
black mangrove (Avicenriia
germinans)
marsh elder (Iva frutescens)
red mangrove (Rhizophora


same as "nontidal"
Tidal flats
Estuarine intertidal/ Marine
intertidal (includes aquatic beds,
beach/bars, flats, reefs, rocky
shores, streambeds, and
unconsolidated shores)
saltwort (Batis maritima)
smooth cordgrass (S..
alterniflora)
                                             10

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The matrix presented in Table 4 is based on the most recent NOAA inventory (1991) and
•shows acreage of selected coastal habitats in Gulf states, by county. The term "unspecified" was used
in some areas when information available from maps and aerial photographs was insufficient to
determine whether the area was tidal or non-tidal. Therefore, NOAA's fresh marsh (unspecified)
category was not included in total coastal acreage in this summary of status and trends.

Summaries of acreages presented in Table 4'are presented in Table 5 and Figures 1 and 2 by
state and habitat type. Even though total wetland acreage has diminished greatly during the last 30
years, the Gulf of Mexico still contains large areas of these valuable habitats (Table 5). Louisiana
and Florida contain approximately 80% of the total 3,762,800 ac (15,234 km2) in the five wetland
categories. Louisiana has the greatest acreage of coastal emergent wetlands with 49% of the total,
followed by Florida (29%), Texas (20%), and Mississippi (2%). Texas contains 54% of the regional
tidal flats, and Florida has 97% of the estuarine forested scrub-shrub, most of which is mangrove
(Figure 1). Of the five major coastal wetland habitats, 66% of the acreage is salt marsh, 17% forested
scrub-shrub, 13% tidal flats, 3% tidal fresh marsh, and 1% forested (Figure 2).

Acreage of wetland habitats along the Gulf coast in selected estuarine drainage areas (EDA) is
given in Table 6. Wetland inventory maps are not yet complete for all EDA's, and the NOAA
document describes the location, dominant wetland type, dimensions, and other characteristics for
twenty-three of the thirty-one major EDA's. This analysis by natural ecological units, rather than
by state or county delineation, is an especially useful baseline in evaluating the potential impacts of
natural and man-induced degradation of specific ecosystems.

Another inventory of wetlands and other habitats is presented by Watzin and Baumann (1988),
who list acreages of the Coastal Barrier Resource System (CBRS) within the Gulf states (Table 7).
The coastal barrier resource system (CBRS) is a network of coastal barriers protected under the
Coastal Barrier Resource Act (CBRA). There are 186 units (islands) in the CBRS, ranging in size
from less than 20 ac (8.1 ha) to more than 49,000 ac (19,838 ha). Barrier islands, barrier spits and
peninsulas, bay barriers, and tombolos (sand or gravel bar that connects an island with the mainland
or another island) are all included in the system. Watzin and Baumann (1988) summarized the results
of a 1982 inventory of the CBRS-and a study of the shoreline change and wetland loss which
occurred in selected units of the system. A discussion of their findings on losses of wetlands from
the coastal barrier system is presented later in this document.

Other habitat inventories are available on a statewide basis. For example, the Environmental
Geologic Atlas project of Texas was initiated in 1969 to produce a thorough regional analysis of
natural resources and processes, lands, water bodies, and other factors for coastal counties. The
11