United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA 620-R-98-004
July 1999
www.epa.gov
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USGS
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The Ecological Condition of
Estuaries in the
Gulf of Mexico
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EPA 620-R-98-004
July 1999
The Ecological Condition of Estuaries in
the Gulf of Mexico
U.S. Environmental Protection Agency
Office of Research and Development
National Health and Environmental Effects Research Laboratory
Gulf Ecology Division
Gulf Breeze, Florida 32561
Interagency Agreement #DW14938557
J. Kevin Summers, Project Officer
This study was conducted in cooperation with
Department of Interior, United States Geological Survey,
Biological Resources Division
Gulf Breeze Project Office
National Health and Environmental Effects Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
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The U.S. Environmental Protection Agency through its Office of Research and Development,
funded and collaborated in the research described here under Interagency Agreement
DW14938557 with the Department of Interior, U.S. Geological Survey, National Wetlands
Research Center. It has been subjected to the Agency's peer and administrative review and
has been approved for publication as an EPA document.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
This report should be cited as:
USEPA. 1999. Ecological Condition of Estuaries in the Gulf of Mexico. EPA 620-R-98-
004. U.S. Environmental Protection Agency, Office of Research and Development, National
Health and Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze,
Florida.
11
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This report, The Ecological Condition of Estuaries in the Gulf of Mexico., was prepared
collaboratively by staff from the U.S. Environmental Protection Agency (USEPA) and the
U.S. Geological Survey (USGS). The staff included Virginia Engle, John Macauley, and
Kevin Summers from the Gulf Ecology Division (GED), National Health and Environmental
Effects Research Laboratory, Office of Research and Development, USEPA, Gulf Breeze,
Florida and Pete Bourgeois, through an Interagency Agreement with the Gulf Breeze Project
Office, National Wetlands Research Center, Biological Resources Division, USGS, Gulf
Breeze, Florida. The report was coordinated through the Gulf of Mexico Program, Stennis
Space Center, Mississippi, and its partners, including USEPA Regions 4 and 6, and USEPA
Office of Water, Florida Department of Environmental Protection, Alabama Department of
Environmental Management, Mississippi Department of Environmental Quality, Louisiana
Department of Environmental Quality, Texas Natural Resources Conservation Commission,
Texas Parks and Wildlife, and Texas Water Development Board. Data was obtained from
these and other sources, including the National Oceanic and Atmospheric Administration,
U.S. Fish and Wildlife Service, Minerals Management Service, and U.S. Bureau of the
Census. All data sources are listed at the end of this report.
We would like to thank the following people for their invaluable assistance in putting this
report together: Lois Haseltine, Renee Conner, and Linda Harwell, Johnson Controls World
Services for desktop publishing, graphics support, and database management; Steve Robb,
USGS for geographic information systems support; Shannon Price, Johnson Controls World
Services, Beth Vairin, USGS, Sheila Howard, National Caucus and Center on Black Aged,
Inc., and James Harvey, USEPA, for technical editor support. Special thanks go to the
technical reviewers of this report: Foster Mayer, Raymond Wilhour, Larry Goodman, and
William Walker of USEPA/GED; James Giattina, Gulf of Mexico Program; John Carlton,
Alabama Department of Environmental Management; Kenneth Haddad, Florida Department
of Environmental Protection; Phil Bass, Mississippi Department of Environmental Quality;
Greg Steyer, Louisiana Department of Environmental Quality; Holly Greening, Tampa Bay
National Estuary Program; Nancy Rabalais, Louisiana Universities Marine Consortium;
Kerry St. Pe, Barataria-Terrebonne National Estuary Program; Larry McKinney, Texas Parks
and Wildlife Department; and Terry Wade, Texas A&M University Geochemical and
Environmental Research Group.
Cover photo of shrimp boat, aerial marsh landscape, and blue crab USGS/NWRC
Cover photo of Snowy Egret ฎDon Baccus (dhogaza@pacifier.com) donb.photo.net/photo_cd/d/b4.html
111
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USEPA U.S. Environmental Protection Agency
EMAP Environmental Monitoring and Assessment Program
EMAP-E Environmental Monitoring and Assessment Program - Estuaries
NEP National Estuary Program
NERRS National Estuarine Research Reserve System
NPDES National Pollution Discharge Elimination System
NOAA National Oceanic and Atmospheric Administration
AD EM Alabama Department of Environmental Management
ALAMAP Alabama Monitoring and Assessment Program
R-EMAP-TX Regional Environmental Monitoring and Assessment Program - Texas
NSSP National Shellfish Sanitation Program
MNET Gulf of Mexico Aquatic Mortality Network
USGS United States Geological Survey
CCMP Comprehensive Conservation and Management Plan
OCS Outer Continental Shelf
AVHRR Advanced Very High Resolution Radiometer
DO Dissolved Oxygen
HAB Harmful Algal Bloom
NSP Neurotoxic Shellfish Poisoning
ER-L Effects Range - Low (Long et al. 1995)
ER-M Effects Range - Median (Long et al. 1995)
PAH Polycyclic Aromatic Hydrocarbon
PCB Polychlorinated Biphenyl
DDT Dichlorodiphenyltrichloroethane
TBT Tributyltin
SAV Submerged Aquatic Vegetation
IV
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Executive
Summary
The Gulf of Mexico is a vast natural resource encompassing the coastal areas of western Florida,
Alabama, Mississippi, Louisiana, and Texas, as well as a portion of Mexico. Many estuaries flow
into the Gulf of Mexico and serve as nursery grounds for fish, habitat for a wide variety of wildlife,
shipping routes, and a source of recreation. Estuarine-dependent species constitute more than 95
percent of the commercial fishery harvests from the Gulf of Mexico, and many important recreational
fishery species depend on estuaries during some part of their life cycle. Gulf estuaries are diverse
and productive ecosystems that provide a variety of valuable resources, including fish and shellfish,
recreation, transportation, and water supply.
Assessing the overall condition of Gulf of Mexico estuaries required incorporating data from other
federal, state, and local monitoring programs to augment the information on ecological indicators
collected by the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and
Assessment Program (EMAP). The resulting document would provide a synthesis of the available
knowledge about the condition of Gulf of Mexico estuaries. This document is intended for use by
scientists and other citizens concerned with the ecological condition of estuaries, as well as by
managers and lawmakers interested in the sustained use of estuaries for commercial and recreational
purposes. It also addresses public concerns about the aesthetic quality of coastal areas vital to
tourism and recreation. By producing this report on the ecological condition of estuaries in the Gulf
of Mexico, we have taken one step in assessing the health of this environmental resource. We have
produced an environmental "report card" to be used as a guide in the evaluation of management
decisions and research directions.
This report is organized in three parts: (1) an introduction that gives background information on the
Gulf of Mexico, estuarine ecology, and the factors that impact estuaries in the gulf, (2) the main
section on priority ecological indicators used to measure the condition of estuaries in the gulf and (3)
an ecological report card that summarizes the data on ecological indicators and provides a rating of
the condition of estuaries in each gulf state and for gulf estuaries overall. Many of the ratings were
based on the percent area of estuaries in each state exhibiting degraded or adverse levels of an
indicator.
Eutrophication, a condition of high nutrients often resulting in low oxygen levels and other adverse
effects, is an important water quality concern for estuaries along the gulf coast. The National
Oceanic and Atmospheric Administration (NOAA) has compared the Gulf of Mexico to other coastal
regions like the middle Atlantic and has ranked the Gulf of Mexico as having the highest number of
point sources of nutrients and the highest percentage of land use devoted to agriculture. We
evaluated monitoring data for nitrogen, chlorophyll, and dissolved oxygen as indicators of
eutrophication. Although most of the estuaries exhibited high nitrogen or chlorophyll or low
v
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Executive Summary
dissolved oxygen concentrations at least once during a survey, many times these conditions were
observed in small rivers or bayous rather than in the entire estuary. Often, the percent area affected
was low. The gulf estuaries had moderate conditions overall for nutrients and dissolved oxygen.
Definite nutrient problems were observed in >25% of the estuarine area in Louisiana and Texas and
definite dissolved oxygen problems were observed in Alabama.
Contaminants in estuarine sediments provide evidence of the accumulation of chemicals from
anthropogenic sources. We compared the concentrations of sediment contaminants to established
guideline values to determine the proportion of estuarine area that could have potential adverse
effects on living organisms. Although detectable levels of contaminants were measured in almost
every estuary in the Gulf of Mexico, <25% of the estuarine area in all states had contaminant
concentrations that exceeded these guidelines.
Wetlands are integral parts of estuarine systems. Declining acreage means habitat loss that may be
the result of commercial and residential development, hydrologic alterations, or dredge and fill
operations. The Gulf of Mexico region contains more than 50% of the coastal wetland acreage in the
U.S. and yet it also has the highest rate of coastal wetland loss. Nine of the top ten estuarine drainage
areas ranked by total wetland area are in the Gulf of Mexico region. The most current estimates of
total wetland loss over the past 200 years range from 41% to 54% for the gulf states. Although
coastal wetlands continue to be altered or destroyed, some estimates indicate that the rate of loss has
slowed. All gulf states were rated as having severe problems with wetland loss.
The condition of benthic (bottom-dwelling) invertebrates, fish and shellfish, birds, and threatened
and endangered species was used to evaluate the health of estuarine fauna. Degraded benthic
communities inhabited <25% of the estuarine area in all gulf states except for Texas. Commercial
fish and shellfish landings may be used as an indicator of population stability while fish biomarkers
are used to measure the health of individuals in the population. Commercial landings of the top four
fisheries (shrimp, menhaden, blue crab, and oyster) are stable in the gulf states while fish biomarkers
indicate fair to poor fish health in Alabama and Texas and good fish health elsewhere. Coastal and
marine bird populations appear to be in good condition throughout the gulf. Four threatened or
endangered species inhabit coastal areas in the Gulf of Mexico: brown pelican, Gulf sturgeon,
manatee, and Kemp's ridley sea turtle. In general, populations of these species are in good to fair
condition in the gulf states.
Public health indicators include shellfish bed closures and chemicals found in edible fish tissue.
Harvest of shellfish (primarily oyster in the Gulf of Mexico) is restricted or prohibited when
concentrations of bacteria or other pathogens reach levels that could impair human health. The gulf
states contain the most acreage of shellfish-growing waters in the U.S. but also have the most acreage
restricted for harvest. All gulf states except Mississippi have >25% of their shellfish-growing waters
restricted for harvest, mostly due to pollution from wastewater treatment plants or other upstream
sources. Advisories may be issued that limit consumption when the concentrations of chemicals in
fish tissue exceed levels known to be harmful to humans. Although seafood consumption advisories
have been issued in all gulf states, the percent of the fish population with high concentrations of
contaminants is relatively low in the gulf overall.
VI
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Disclaimer ii
Acknowledgments iii
Acronyms iv
Executive Summary v
Introduction 1
Estuaries and Their Value 3
Population Distribution 5
Consequences of Human Usage 6
Land Use Patterns 7
Natural Habitat Characteristics 9
Federal Response to Concerns about Estuaries 11
Summary 12
Freshwater Inflow 13
Water Quality 15
Eutrophication 16
Nutrients 17
Chlorophyll a 18
Dissolved Oxygen 20
Harmful Algal Blooms 23
Sediment Contaminants 25
Habitat Change 29
Wetlands 29
Submerged Aquatic Vegetation 31
Vll
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Biological Integrity 33
Benthos 33
Commercial and Recreational Fisheries 35
The Red Drum Fishery 36
Fish Biomarkers 37
Coastal and Marine Birds 38
Threatened and Endangered Species 40
Public Health 43
Shellfish - Growing Waters 43
Contaminants in Fish and Shellfish 44
Fish Kills 46
Ecological Report Card 47
Data Sources 53
Appendix I: National Estuary Programs 65
Appendix II: Characteristics of Estuaries in the Gulf of Mexico . . 69
Vlll
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Introduction
Introduction
The U.S. Gulf of Mexico region encompasses two biogeographical provinces: 1) The
Louisianian Province which covers estuarine systems from Rio Grande, Texas, to Anclote
Key, Florida and 2) the West Indian province which includes the western Florida coast from
Tampa Bay to the Florida Keys (Fig. 1; estuaries in Mexico were not included in this
assessment). This expanse includes many large estuarine systems (surface area > 280 km2)
such as Corpus Christi Bay, Galveston Bay, Sabine Lake, Vermilion-Atchafalaya Bay,
Terrebonne Bay, Barataria Bay, Breton Sound, Lake Pontchartrain, Mobile Bay, Pensacola
Bay, Choctawhatchee Bay, Tampa Bay, and Florida Bay, in addition to several hundred small
estuaries.
Estuaries are bodies of water that are balanced by freshwater and sediment influx from rivers
and the tidal actions of the oceans, thus providing transition zones between the freshwater of
a river and the saline environment of the sea. The result of this interaction is an environment
where estuaries, along with their adjacent marshes and seagrasses, provide a highly
productive ecosystem, that supports wildlife and fisheries and contributes substantially to the
economy of coastal areas. As spawning, nursery, and feeding grounds, estuaries are
invaluable to fish and shellfish. Estuarine-dependent species constitute more than 95 percent
of the commercial fishery harvests from the Gulf of Mexico, and many important recreational
fishery species depend on estuaries during some part of their life cycle. Gulf estuaries are
diverse and productive ecosystems that provide a variety of valuable resources, including fish
and shellfish, recreation, transportation, and petroleum and minerals.
What began as an overall summary of the activities of the USEPA's Environmental
Monitoring and Assessment Program for Estuaries (EMAP-E) in the estuaries of the
Louisianian and West Indian provinces (the Gulf of Mexico and south Florida) has evolved
into the report you see here. One of EMAP-Es goals was to assess ecological conditions
using environmental monitoring data from multiple spatial and temporal scales. From 1991
to 1995 EMAP collected data on ecological indicators from estuaries in the Gulf of Mexico.
The ecological condition of these estuaries was reported in annual statistical summaries that
enumerated areas found to have deleterious conditions (e.g., low dissolved oxygen, degraded
benthic habitat, or contaminated sediments).
Evidence of the diminishing quality of our estuaries has been found in the large amounts of
debris washing up on shores; beach closures due to trash, bacteria, or red tide; reduced water
clarity and water quality; fish consumption advisories issued to warn consumers of
contaminated fish; shellfish bed closures; and fishing bans. This evidence contributes to the
public's perception that something must be done to restore our estuaries to a healthy state. In
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Mississippi/ Alabama
Choctawhatchee Bay
Lake / Pensacola Bi
Borgne Perdido Bay
Bay
/ Apalachicola Bay
St. Andrews Bay Suwannee
River
Sabine
Lake
Galveston Atchatalaya and
Terrebonne and
Tlmbalier Bays
Matagonda Bay
San Antonio Bay
Aransas Bay
Corpus Christ Bay
Tampa Bay
Sarasota Bay A
Rookery Bay
Ten Thousand Islands
Florida Bay
Fig. 1. Estuarine systems located in the Gulf of Mexico (United States; NOAA 1997).
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Introduction
order to effectively gauge whether future management actions are improving the situation,
however, a baseline for gulf-wide estuarine conditions must first be established. The current
report focuses on the ecological condition or health of estuaries in the Gulf of Mexico, using
indicators that are well established in the scientific community and incorporating both the
most current information and historical trend data where available. This report provides
much-needed information to scientists and others concerned with the ecology of estuaries,
and to managers and lawmakers concerned with the sustained use of estuaries for commercial
and recreational purposes. It will also address public concerns about the aesthetic quality of
coastal areas that are vital to tourism and recreation.
Estuaries and Their Value
Estuaries and wetland environments are intertwined. Coastal emergent wetlands border
estuaries and the Gulf of Mexico and include tidal saltwater and freshwater marshes and
mangroves. Encompassing over two million hectares (five million acres or more than half of
the national total), the Gulf of Mexico coastal wetlands serve as essential habitat for a diverse
range of species. These wetlands are used by shorebirds, migratory waterfowl, fish,
invertebrates, reptiles, and mammals. A large percentage of the migrating waterfowl and
migrant Neotropical birds of the U.S. utilize these coastal habitats. Mudflats, salt marshes,
mangrove swamps, and barrier island habitats also provide year-round nesting and feeding
grounds for abundant populations of gulls, terns, and other shorebirds. Gulf estuaries and
marshes and associated watersheds provide habitat for many threatened and endangered
species, including sea turtles (e.g., leatherback, hawksbill, Kemp's ridley, loggerhead, and
green), piping plover, bald eagle, brown pelican, Gulf sturgeon, West Indian manatee, and
American crocodile. Estuaries and wetlands support complex food webs that provide an
abundant food source for juvenile and adult fishes (Fig. 2). In addition to providing habitat,
wetlands also improve water quality by filtering pollutants and sediment and offer a buffer
zone to protect upland areas from flooding and erosion.
Estuaries provide humans with a variety of uses. They both supply water and provide a point
of discharge for municipalities and industries, and support agriculture, commercial and sport
fisheries, and recreational uses such as swimming, diving, and boating. The complex
network of channels and wetlands within the gulf shoreline provides habitat for estuarine-
dependent commercial and recreational fisheries. In the Gulf of Mexico commercial and
recreational fisheries and tourism are economically important. Tourism in the gulf coast
states contributes an estimated $20 billion to the economy each year. The Gulf of Mexico
ranks second only to Alaska in total commercial landings. The rich waters yielded
approximately 684 million kg (1.51 billion pounds) offish and shellfish in 1996. This
represented at least a two-fold increase in the commercial landings offish in the gulf since
1950, with the peak years from 1982 to 1987 yielding more than one billion kg offish and
shellfish annually (Fig. 3). Worth more than $689 million at dockside, the 1996 harvest
represented 33% of the total annual domestic harvest (excluding Alaska) of commercial fish.
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Introduction
-a-*
Phytoplankton
Fish and
invertebrate
Zooplankton, ป ft
filter feeders Fish, invertebrates;! if
and their larvae / /
Detritus feeders and
decomposer community
Benthic
invertebrates
Fig. 2. Conceptual diagram of the food web in Gulf of Mexico estuaries (redrawn from Weber, et al.,
1992).
The gulf boasts the largest and most valuable shrimp fishery in the U.S. (99 million kg or
69% of the national total in 1996) and also contributed 57% of total oyster production in the
U.S. in 1996. Other important gulf
fisheries include crabs and spiny
lobsters, menhaden, herring, mackerel,
tuna, grouper, snapper, drum, and
flounder. The entire Gulf of Mexico
fishery yields more fmfish, shrimp, and
shellfish annually than the south and
mid-Atlantic, Chesapeake, and Great
Lakes regions combined. The gulfs
waters draw millions of sport fisherman
and beach users each year. It is
estimated that the gulf supports more
than one-third of the national marine
recreational fishing, hosting 4.8 million
anglers in 1995, who caught an
estimated 42 million fish.
1940 1950 1960 1970 1980 1990 2000
Fig. 3. Commercial landings in million kg of all species
from Gulf of Mexico waters from 1950 to 1996 (National
Marine Fisheries Service).
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Introduction
Gulf oil and gas production are equally valuable to the region's economy and are a critical
part of the nation's total energy supply. In 1990, more than 1,600 Outer Continental Shelf
(OCS) leases were in production (Melancon et al 1997). OCS royalties from the Gulf of
Mexico annually contribute about $3 billion to the Federal Treasury. The Gulf of Mexico
ranks second only to Alaska in terms of potential petroleum reserves, contributing 13% of the
U.S. domestic oil and gas production in 1994 (Lore et al 1996). The Minerals Management
Service projects a doubling in Gulf of Mexico oil production by the year 2000. Petroleum
and chemical products also constitute the majority (69%) of shipping tonnage that passes
through gulf ports and harbors.
Shipping and marine transport is an important industry in the gulf. Seven of the top ten
busiest ports in the U.S. in terms of total tonnage are located in gulf estuaries (Port of South
Louisiana, Houston, Baton Rouge, New Orleans, Port of Plaquemines, Corpus Christi, and
Tampa). Shipping tonnage in the gulf has increased from 83 million tons in 1982 to 118
million tons in 1995 with 98% of the traffic traveling via the intracoastal waterway.
Population Distribution
20,000]
n
ฃ 15,000
o 10,000
I
g 5,000
0
1960 1970 1980 1990 1994*
* preliminary estimate
Millions of people live along the Gulf of
Mexico coastline, attracted by its shorelines
and waterways, temperate climate, and
abundant resources. The 1990 census
indicated that coastal counties in the Gulf of
Mexico accounted for only 11% of the
nation's total coastal population and had the
lowest population density (187 persons per
square mile) of all coastal regions of the
continental U.S. (i.e., northeast, southeast,
Great Lakes, and Pacific, excluding Alaska
and Hawaii). The coastal counties in the gulf
are experiencing the second fastest rate of
growth; between 1970 and 1980, the
population grew by more than 30 percent, and between 1980 and 1990, the population grew
by more than 16% (Fig. 4). Texas and Florida have the largest populations in coastal
counties of the Gulf of Mexico and similar relative growth rates (Fig. 4). All but four coastal
counties in Florida had more than a 100% increase in population from 1950 to 1990 (Fig. 5).
According to projections by the U.S. Department of Commerce, the gulfs total coastal
population will increase by 144 percent between 1960 and 2010, to almost 18 million people.
This increase in population is a concern due to the added impacts and competing needs for
the gulfs natural resources.
A growing population will require land to expand into, converting other habitats such as
forest or agriculture to urban areas. Increased housing and road construction puts pressure on
the receiving waters that have to assimilate the additional storm water runoff from the
Fig. 4. Population estimates based on the 10-
year Census for coastal counties in the Gulf of
Mexico (U.S. Census Bureau).
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Introduction
Percent Population Change
1950-90
Fig. 5. Percent change in population from 1950 to 1990 in counties of Florida, Alabama, Mississippi,
Louisiana, and Texas (U.S. Census Bureau).
expanding impervious surfaces associated with urbanization. A growing population also
generates more wastewater and solid waste that require disposal and increase emission of
pollutants to the air. Pollutants carried in water runoff and by atmospheric deposition affect
the health of estuaries.
Consequences of Human Usage
The ability of estuaries to function as nursery grounds depends upon the quantity, timing, and
location of freshwater inflows. Estuarine ecosystems are impacted by humans, primarily via
upstream withdrawals of water for agricultural, industrial, and domestic purposes;
contamination by industrial and sewage discharges and agricultural runoff carrying pesticides
and herbicides; eutrophication caused by excessive nutrient inputs from a variety of nonpoint
(agricultural drainage, faulty septic systems) and point sources (sewage treatment plants); and
habitat alterations (e.g., construction and dredge and fill operations). Common effects of
human use of estuaries include degraded natural habitats, declining plant and animal
populations, diminishing fish and shellfish harvests, and impaired water quality. These
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Effects of human use on estuaries:
Texas, Louisiana, and Alabama ranked first, second, and fourth in the nation in 1995 in
terms of discharging the greatest amounts of toxic chemicals.
More than half of the oyster producing areas along the gulf coast are permanently or
conditionally closed. These closure areas are growing as a result of increasing human and
domestic animal populations along the gulf coast.
Diversions and consumptive water use for human activities have resulted in significant
changes in the quantity and timing of freshwater inflows to the Gulf of Mexico habitats.
Louisiana is losing valuable coastal wetlands at the rate of approximately 65 km2 (25 mi2)
per year.
Up to 18,000 km2 (7,000 mi2) of oxygen deficient (hypoxic) bottom waters have been
documented off the Louisiana and upper Texas coasts.
Source: Gulf of Mexico Program, 1994.
effects are clearly observable in some estuaries of the Gulf of Mexico. Growth of human
populations in the estuarine watersheds, combined with industrial and agricultural discharges,
places more demands on the natural resources. In some areas, estuaries are unable to safely
assimilate the amounts of pollution being added to the system and become adversely affected.
Most problems observed in estuaries are related to land use practices and to human
population density.
Land Use Patterns
Understanding land use within watersheds is a prerequisite to understanding the ecological
condition of Gulf of Mexico estuaries. Gulf estuaries encompass approximately 30,000 km2
(42% of the total estuarine surface area of the U.S. excluding Alaska). Including the
Mississippi River, the Gulf of Mexico drainage area encompasses more than 4 million km2 or
more than 55% of the total area of the conterminous U.S. (Fig. 6). The Gulf of Mexico
receives an average of 27,473 cubic meters per second of freshwater inflow daily (more than
50% of the daily average for the continental U.S.). Although the land use within the entire
watershed determines what materials are carried by runoff into estuaries, we estimated the
percent area that was classified into land use categories of just the five gulf states and not the
entire watershed. Forest and agriculture comprise approximately 58% of the land area in the
five gulf states (Fig. 7). While forests provide filtration for sediment and nutrients from
runoff, as well as structure to stabilize shoreline and reduce erosion, many of the forests are
in areas distant from the shores of the estuarine waters. Many are being replaced by urban and
agricultural expansion.
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Introduction
V.
Gulf of Mexico
\
Mississippi River drainage
D Other drainage
..
C2
Fig. 6. Sources of freshwater inflow into the Gulf of Mexico from the Mississippi River and
non-Mississippi watersheds. (USEPA, Region 6)
Barren
Agriculture
Forest
Rangeland
Water
Shrub/Grassland
Fig. 1. Satellite Advanced Very-High Resolution Radiometer (AVHRR) image of vegetation types in the gulf
coast states (USGS Earth Resources Observation Systems Data Center).
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Introduction
Agricultural land can be divided into pasture and cropland. Pasture land consists of grassy
areas for raising and feeding livestock, while cropland consists of cultivated areas which
provide various food products. Other land uses include wetland habitats (17%) and urban
areas (5%) that are generally located close to the coastline.
Natural Habitat Characteristics
Salinity, temperature, water depth, and sediment type are the primary natural habitat
characteristics that affect estuaries. Water depth affects the distribution of shellfish and
submerged aquatic vegetation. Salinity is influenced by rainfall and tidal surges and affects
the distribution of benthic animals, fish, and plants. Temperature is relatively stable in Gulf
of Mexico estuaries, but changes in temperature can influence when animals feed, reproduce,
move locally, or migrate. Sediment type is an important factor determining the composition
of the benthic community and in the sediment's potential for absorption and adsorption of
contaminants.
Average water depth of estuaries in the Gulf of Mexico is 3 m, with maximum depths
(greater than 10m) occurring in dredged shipping channels and the Mississippi River.
Gulf sediments change from terrigenous to carbonate as one goes from west to east.
EMAP's survey of estuarine sediments found that they are primarily mud (more than 80%
silt-clay) and mixed mud-sand (20-80% silt-clay) from Tampa Bay, Florida, to the Rio
Grande, Texas (Fig. 8). In south Florida, however, sediments are primarily sand (less
than 20% silt-clay).
Water clarity is valued by society and contributes to the maintenance of productive
biological communities. We define low water clarity as less than 10% transmission of
ambient light at 1m depth or water in which divers would not be able to see their hands
when held at arm's length. Moderate water clarity is defined as 10-25% transmission of
ambient light at 1m depth or as water in which waders are unable to see their feet in
waist-deep water. Few gulf estuaries have low water clarity (Fig. 8).
Estuaries are characterized by gradients in salinity from near fresh water at the mouths of
tributaries to near marine at the mouth of the estuary. Gulf of Mexico estuaries are
predominantly polyhaline (more than 18 ppt) during the summer months (Fig. 8).
Shallow estuaries are less able than are deeper ones to store heat, and water temperature
fluctuates from 4 to 32ฐC annually.
Stratification of the water column occurs when layers of water with different salinity or
temperature do not mix. In the gulf this usually occurs during the summer but is highly
variable and often diurnal in nature. Benthic organisms are exposed to rapidly fluctuating
dissolved oxygen and salinity due to tides and inflow.
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Introduction
Sediment Characteristics
Tampa - Rio Grande
South Florida
Mixed
.44%
Mixec
49%
Water Clarity
Moderate
17%
Moderate
33%
Bottom Salinity
>18ppt
50%
<5ppt
23%
5-18ppt
11%
5-18ppt
27%
>18 ppt
80%
Fig. 8. Distribution of sediment characteristics, water clarity, and salinity condition in
estuaries from the Gulf of Mexico. Percentages represent percent area of the Louisianian
Province (Tampa-Rio Grande) and the West Indian Province (South Florida); USEPA
EMAP-E Database for the Louisianian [1991-1994] and West Indian [1995] Province.
10
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Introduction
Federal Response to Concerns about Estuaries
In 1987, the National Estuary Program (NEP) was started by the USEPA "to protect and
restore the health of estuaries while supporting economic and recreational activities." Since
then, seven NEP's (Fig. 9) have been established in the Gulf of Mexico, representing
partnerships between government agencies responsible for managing estuarine resources and
people who depend on estuaries for their livelihood and quality of life. EMAP focused much
of its early efforts on determining the status of estuarine habitats nationwide. More recently,
attention has been focused on estuaries by the Estuary Habitat Restoration Partnership Act
(S.1222, introduced in Congress in 1997), which is specifically designated to provide
assistance to communities to restore estuarine habitat.
To achieve the goals of the NEP, the USEPA helps create local
partnerships between government agencies responsible for managing
estuarine resources and the people who depend on the estuaries for
their livelihood and quality of life. A major benefit of the NEP is
that it brings communities together to decide the future of their own
estuaries. Citizens, business leaders, educators, and researchers
work with representatives from government agencies to identify
their estuary's problems and to recommend solutions. Each NEP
formulates a Comprehensive Conservation and Management Plan
(CCMP) that serves as a blueprint for revitalizing the estuary and
protecting it from new dangers. The Gulf of Mexico NEP's are demonstrating practical and
innovative ways to revitalize and protect their estuaries (see Appendix 1 for brief descriptions
of individual NEPs).
Recognizing the natural value of estuaries, Congress created
the National Estuarine Research Reserve System (NERRS)
in 1972. NERRS is dedicated to fostering a system of
estuary reserves that represents the wide range of coastal and
estuarine habitats found in the U.S. and its territories. In
pursuit of this goal, NERRS works with federal and state
authorities to establish, manage, and maintain reserves, and
to provide for their long-term stewardship. Research and
education are also crucial to meeting this goal. Reserves in
the system serve as laboratories and classrooms where the
effects of both natural and human activity can be monitored
and studied. To date, 22 estuaries nationwide have been
designated as NERRS, 3 of which are located along the gulf
coast (Fig. 2; see Appendix 1 for brief descriptions of
individual NERRS).
11
-------
Introduction
Texas
Mississippi
Weeis B
Mobile Bay
Barataria-Terrebonne
Galveston Bay
Corpus Christ! Bay
Tampa Bay
Sarasota Bay
Charlotte Harbor
Rookery Bay
NEP
O NERRS
Fig. 9. Locations of National Estuary Programs and National Estuarine Research Reserve Systems in the
Gulf of Mexico (USEPA).
Summary
This overview of the estuarine resource characteristics in the Gulf of Mexico sets the context
within which to describe the state of the Gulf of Mexico estuaries. For example, a
combination of environmental factors may underlie changes in fish abundance, size, and
species composition in estuaries. Among these factors are turbidity (water clarity) from
resuspension of sediments and phytoplankton growth, salinity, depth, temperature, nutrient
enrichment, and pollution. Susceptibility offish to poor water quality is, in part, determined
by the estuarine characteristics. This report provides a review of the state of the estuarine
environment in the Gulf of Mexico region. This is a summary of historical information and
of our current state of knowledge about a set of indicators of estuarine condition for water
and sediment quality, habitat change, condition of living resources, and aesthetic quality.
Each indicator is briefly discussed relative to its importance for understanding estuarine
condition; then the current condition of the indicator is summarized. Each indicator is then
used to assess the status of estuarine condition relative to the indicator. This report is an
assessment of the health of estuaries in the Gulf of Mexico based on historical and current
conditions. It serves to emphasize how important estuaries are and why we should continue
to preserve, protect, and correct problems within the gulfs estuaries.
12
-------
Freshwater
Inflow
Functions of freshwater inflow in estuaries:
Provide a food supply by stimulating both
photosynthesis and microbial
decomposition;
Deposit sediments that stabilize coastal
wetlands against erosion, subsidence, and
sea level rise;
Drive estuarine circulation and establish
salinity gradients; and
Create a range of salinities under which
plants and animals thrive.
Source: Gulf of Mexico Program, 1994.
Estuaries function as transition zones
between the freshwater of a river and the
saline environment of the sea and, by
definition, receive freshwater inflows.
The ability of an estuary to function
properly and to sustain populations of
animals and plants depends on the
quantity, quality, timing, and location of
freshwater inflows. The effects of the
diversion of freshwater inflow is of great
concern to resource managers. Whether
freshwater inflow is diverted away from
an estuary (e.g., for agriculture or water
supply) or into an estuary (e.g., effluent,
river discharge diversion), the effects
upon an estuary include habitat loss,
changes in salinity, and altered nutrient
and sediment loads. These changes
affect wetlands, phytoplankton, zooplankton, benthos, and fish directly and indirectly by altering
suspended sediments, dissolved oxygen, water temperature, pH, and water clarity.
The areas throughout the Gulf of Mexico that have been most adversely affected by alterations in
freshwater inflow are Florida Bay, the Louisiana coastal marshes, and the Texas gulf coast. Florida
Bay receives freshwater inflow from the Everglades, where the natural sheet flow through this
wetland has been altered by canals and water management structures. Seagrass die-off, a declining
shrimp fishery, algal blooms, and fish kills in Florida Bay have been attributed to the effects of
altered freshwater inflow. The vast majority of the freshwater inflow to the Gulf of Mexico comes
through the Mississippi River delta. Historically, the natural flow from the Mississippi River
deposited sediments on the coastal marshes and deltas of Louisiana; this accretion of sediment
countered the loss of land due to subsidence. The Mississippi River's flow is now controlled and
managed by levees and dikes. Because of this change in the natural flow, sediments from the
Mississippi River are now deposited in the Gulf of Mexico, and the rate of land loss exceeds the rate
of accretion in Louisiana's coastal wetlands. In Texas, reduced freshwater inflow to estuaries is of
concern to resource managers primarily because of the adverse effects of salinity changes on
commercial fish and shellfish as well as other estuarine species. Altered freshwater inflow indirectly
affects the metabolism, reproduction, and migration of fish and shellfish as well as other organisms
that inhabit estuaries. Texas state agencies are currently assessing the freshwater inflow
requirements of estuaries in order to sustain a healthy ecosystem and productivity offish, shellfish,
and other estuarine life.
13
-------
14
-------
Water Quality
Not
surveyed
22%
Water
quality
Total estuaries
= 39,666 sq. km.
Total impaired
11,072 sq. km.
^^^-
Leading Causes
Organic enrichment / low DO
Siltation
Habitat alteration
Salinity / TDS / chlorides
Oil and grease
Pathogen indicators
Nutrients
(
3
1
DFL
DAL
DMS
DLA
TX
I 20 40 60 80
% of Impaired Estuarlne Area
Leading Sources
Hydromodification
Petroleum
Industrial sources
Land disposal
Municipal sources
Agriculture
Urban runoff
(
I
II I
|J|" '|
II I
DFL
AL
DMS
DLA
TX
20 40 60 80
% of Impaired Estuarine Area
Fig. 10. Summary of classification of estuaries in
terms of water quality from 1996 305(b) reports
submitted by Florida, Alabama, Mississippi,
Louisiana, and Texas.
In the 25 years since the passage of the
Clean Water Act, billions of pounds of
pollution have been prevented from
entering waterways and the number of
rivers lakes, streams, and estuaries that
are safe for swimming and fishing has
doubled (USEPA 1997). Pursuant to
Section 305(b) of the Clean Water Act,
the states must report on the status of
water quality in their jurisdiction every 2
years. The results from the 1996
assessment of water quality in estuaries
and coastal waters of the Gulf of Mexico
are shown in Fig. 10. Estuaries are
classified according to their designated
beneficial uses, which represent the
desirable activities that water quality
should support. For estuaries these
include primarily aquatic life support, fish
consumption, or recreation. States may
require an individual estuary to support
multiple uses. The states are responsible
for conducting monitoring and assessment
programs to evaluate whether or not the
water quality in estuaries is fully,
partially, or not supporting of the
designated uses. In addition, the states
identify indicators that document the
impact of water quality degradation.
States also identify pollutants or processes
that are responsible for degraded water
quality. The percent of a state's estuaries
that has impaired water quality when
tracked over time is a good indicator of
whether or not efforts to improve
estuarine water quality are successful. Of
the 78% of total estuarine area in the gulf
15
-------
Water Quality
that was surveyed in 1994-95, 65% fully supported designated uses. Of the estuarine area
that was impaired (35%), most of the impairment came from pathogen indicators (e.g. fecal
coliform) and eutrophication indicators (e.g. nutrients, organic enrichment, and low dissolved
oxygen). The primary sources of impairment of estuaries included municipal and industrial
point sources as well as nonpoint sources like urban runoff, agriculture, and land disposal
from septic tanks.
Evaluating the water quality in estuaries involves many levels of monitoring and regulation
including National Pollution Discharge Elimination System (NPDES) permits for discharges
into estuaries; evaluation of wastewater treatment plant effluent; and monitoring for bacteria
(fecal coliform), salinity, and dissolved oxygen. The water quality of estuaries affects all
classes of biota that inhabit this ecosystem, including humans. The quality of estuarine
waters determines whether or not (1) we can consume the fish and shellfish from estuaries,
(2) we can swim safely without fear
of infection, (3) we can inhabit
waterfront property without the
aesthetic nuisance of algal blooms,
noxious odors, or masses of dead and
decaying fish, and (4) all levels of
biota in the estuarine food web can
exist in a healthy, stable environment.
Some of these water quality issues
will be discussed in a later section on
public health.
Eutrophication
Some nutrient inputs to coastal waters
are necessary for a healthy, functional
estuarine ecosystem. When
sediments, sewage, or fertilizers are
introduced into an estuary, however,
the concentration of available
nutrients can increase beyond natural
background levels, resulting in a
condition known as eutrophi cation
(Fig. 11). Even relatively modest
increases in the concentration of
nitrogen or phosphorus may be
sufficient to trigger an algal bloom.
In addition to being unsightly and
malodorous, masses of algae can
deprive an estuary of much-needed
oxygen, interfere with swimming and
Phytoplankton Bloom
ป thrives on nutrients
Dissolved Oxygen
from wave action
and photosynthesis
D.O. trapped
in lighter layer
^ D.O. used up by
1mjcroorganism respiration
'*ซ Nutrients
I by bottom sediments
).O. Consumed
Fish
able to avoid
hypoxia
Shellfish
unable to
escape
hypoxia
Decomposition of organic,
matter in sediments
Fig. 11. Conceptual diagram of the conditions that may
lead to eutrophication in estuaries (redrawn from USEPA,
1998; D.O. = Dissolved Oxygen).
16
-------
Water Quality
boating, and outcompete native submerged aquatic vegetation. Although algae during
periods of light produce oxygen as a result of photosynthesis, metabolic processes such as
respiration during periods of darkness and decomposition can use up dissolved oxygen in the
water column. Natural stratification exacerbates this condition and the bottom water quickly
becomes devoid of oxygen (hypoxic or anoxic). Oxygen replenishment in the bottom water
is diminished because the heavier, saltier water layer on the bottom is resistant to mixing with
the lighter, fresher water on the surface. Oxygen depletion can also occur in unstratified
waters, however. The lack of oxygen forces fish and mobile benthic invertebrates to migrate
out of an area. In extreme cases anoxia can lead to fish kills. Organisms living in the
sediments that cannot escape are variably affected as the oxygen levels decline. State and
Federal agencies monitor indicators of eutrophication in estuaries including concentrations of
nitrogen and phosphorus, chlorophyll a, reports of algal blooms, and dissolved oxygen.
Nutrients
Nitrogen and phosphorus are the primary anthropogenic nutrient inputs of concern in coastal
waters, with nitrogen being more important in marine and estuarine systems and phosphorus
being more important in freshwater systems. Monitoring concentrations of nitrogen in
estuarine waters provides an indicator of the potential of a water body to become eutrophic.
Although nutrients are difficult to control (primarily because they are recycled within an
estuary and often come from nonpoint sources), frequent monitoring in estuaries can serve as
an early warning in an effort to prevent eutrophication.
The major nonpoint sources of nitrogen are fertilizer, animal manure, and atmospheric
deposition. Fertilizer nonpoint source runoff can account for up to 25% of the nutrient input
to estuaries. The highest levels of nitrogen fertilizer use (Fig. 12) in the nation occur within
the Mississippi River drainage basin.
Point sources consist mainly of wastewater treatment plants and other industries. According
to the NO AA National Estuarine Inventory (1990), the Gulf of Mexico region ranks highest
of all coastal regions in the U.S. in the number of wastewater treatment plants (1,300),
number of industrial point sources (2,000), percent of land use devoted to agriculture (31%),
and application of fertilizer to agricultural lands (62,000 tons of phosphorus and 758,000 tons
of nitrogen).
The NOAA Estuarine Eutrophication Survey indicated that high concentrations of total
dissolved nitrogen were observed in up to 19% of the estuarine area of the gulf (Fig. 13) and
that for 8 estuaries these high concentrations were persistent year round. Rabalais (1992)
reported that out of 58 estuarine areas in the Gulf of Mexico for which information was
available, 28 had evidence of a definite or potential problem with nutrient increases. State
water quality inventories [1996 305(b) reports], indicated that the majority of estuaries in
each state were rated with acceptable nitrate concentrations. Of those estuaries in each state
17
-------
Water Quality
Nitrogen Use
Tons fxw Square Mite
60 |-lg/L) conditions were observed in
seven estuaries and that high chlorophyll concentrations (20-60 |-lg/L) were observed in 18
estuaries (Fig. 13).
18
-------
Water Quality
Nitrogen
High(>1 mg/L)
Medium (>0.1, < 1 mg/L)
OLow(>0, <0.1 mg/L)
o Unknown
Chlorophyll a
ฎ Hypereutrophic (>60|jg/l)
High (>20, <60|jg/l)
Medium (>5, <20|jg/l)
O Low (>0,<5ug/l)
o Unknown
Fig. 13. Concentrations of nitrogen (mg/1) and chlorophyll a (|lg/l) observed in estuaries of the Gulf of
Mexico based on the Estuarine Eutrophication Survey (NOAA, 1997).
19
-------
Water Quality
Dissolved Oxygen
Because dissolved oxygen (DO) is an indicator of the habitability of estuarine waters for
marine life, DO is routinely measured by monitoring programs interested in characterizing
the eutrophic state of estuaries. DO is recognized as an indicator of the extent of
eutrophication because wide fluctuations in DO often result from increased primary
productivity and may reflect prior nutrient loading. DO concentrations may also vary
because of natural processes (stratification, depth, wind-induced mixing, tidal fluxes). DO is
necessary for respiration in most aquatic animals but different biota have different
requirements for adequate DO. Hypoxia may increase stress from other factors (e.g.,
contaminants) on marine organisms, whereas anoxic conditions produce toxic hydrogen
sulfide which can be lethal to marine biota.
Although many states require DO concentrations of 4-5 mg/L for estuaries to meet their
designated use criteria, hypoxia is often defined as DO < 2 mg/L, and anoxia as DO < 0.1
mg/L. Sufficient evidence exists that DO < 2 mg/L is extremely stressful to most aquatic
organisms. EMAP reported the occurrence of hypoxia in 10% of bottom waters of the
Louisianian Province during summer sampling from 1991 to 1994, but in only 3% of bottom
waters in south Florida in 1995 (Fig. 14). The NOAA Estuarine Eutrophi cation Survey
reported periodic hypoxia in 30 of 37 estuaries (25% of estuarine area) and anoxia in 16
estuaries (6% of estuarine area; Fig. 14). The apparent discrepancies between the EMAP and
NOAA assessments of hypoxia were due to programmatic differences in design and
interpretation. Low DO was usually observed from June through October and was primarily
driven by stratification of the water column.
Fig. 14. Estuaries in the Gulf of Mexico with observed dissolved oxygen < 2 mg/L (marked
with red dots) on at least one sampling visit during the summer (USEPA, EMAP Database for
the Louisianian [1991-1994] and West Indian [1995] Provinces).
20
-------
Water Quality
Mobile Bay, the largest estuary in Alabama, is a good
example of a "Priority Hypoxia Area" identified by
Rabalais (1992). It is relatively shallow (avg. depth 3
m) with a few deep holes and a dredged shipping
channel. Mobile Bay has a historic problem with
seasonal hypoxiathat often culminates in "jubilees,"
where fish and invertebrates migrate to the shore
attempting to escape low DO. Alabama's Department of
Environmental Management (ADEM) implemented an
intensive estuarine monitoring program (ALAMAP -
Coastal) in 1993. Although the extent and duration of
hypoxia in Mobile Bay varies annually, ALAMAP -
Coastal measured low DO in more than 50% of the
bottom water area in Mobile Bay during the summers of
1993 and 1994 (Fig. 15). Periodic hypoxia in Mobile
Bay is part of the natural ecology and is most often
related to salinity patterns and the degree of water
column stratification.
Dissolved Oxygen
DO mg/L
Fig. 15. Dissolved oxygen conditions
observed in Mobile Bay, Alabama
during the summer of 1994 (Alabama
Department of Environmental
Management 1997).
21
-------
22
-------
Harmful Algal
Blooms
Microscopic, single-celled plants
(phytoplankton) serve as the primary
producers of energy at the base of the
estuarine food web (Fig. 16). Some species
of phytoplankton grow very fast, or "bloom,"
and accumulate into dense, visible patches
near the surface of the water. Although the
causes of algal blooms are not entirely
known, scientists suspect that blooms occur
as a result of a combination of high
temperatures, a lack of wind, and, frequently,
nutrient enrichment. Some algal blooms are
called brown tides, and, while not harmful to
humans, they cause serious ecosystem
impacts due to decreases in light penetration
and dissolved oxygen. Brown tides can cause
seagrass die-offs and fish kills. Some algae produce potent neurotoxins that can be
transferred through the food web, where they cause damage, even death, to animals from
zooplankton to humans.
Fig. 16. Mixed bloom of dinoflagellates. Photo
credit: Don Anderson, Woods Hole
Oceanographic Institution.
The most well-known harmful algal bloom (HAB)
events in the Gulf of Mexico involve blooms of
Gymnodinium breve (also known as red tides; Fig.
17), which occur regularly in the fall off the coasts
of Florida and Texas. This organism discolors the
water red (although other less harmful algae can also
discolor the water red) and has been implicated in
fish kills and the deaths of manatee and other marine
mammals. G. breve produces brevetoxins that cause
Neurotoxic Shellfish Poisoning (NSP). NSP
induces gastrointestinal and neurological symptoms
in humans that, although debilitating, are not fatal.
In addition, toxic aerosols are formed by wave
action and can produce asthma-like symptoms in
humans. This often leads to beach closures.
Fig. 17. Electron photo micrograph of
Gymnodinium breve. Photo credit:
Department of Environmental Protection,
Florida Marine Research Institute.
23
-------
Harmful Algal Blooms
Neurotoxic Shellfish Poisoning
Ciguatera Fish Poisoning
AAmnesic Shellfish Poisoning
^ Brown tide
Fish kills
0 Macroalgal proliferation
Fig. 18. Occurrence of HAB-related events in the Gulf of Mexico (National
Office For Marine Biotoxins and Harmful Algal blooms, Woods Hole
Oceanographic Institution).
Prior to 1972, NSP and fish kills due to harmful algal blooms only occurred along the gulf
coasts of Florida and Texas in relatively localized areas. In the fall of 1996, a bloom of G.
breve spread into Alabama, Louisiana, and Mississippi waters for the first time (Fig. 18).
Brown tides have occurred in the Laguna Madre area of the Texas coast since 1990. The
NOAA Estuarine Eutrophication survey indicated that biological resource impacts caused by
nuisance algae occur in 22 estuaries and by toxic algae in 25 estuaries in the Gulf of Mexico.
The causes of the increase in number and
distribution of major harmful algal blooms are
unknown, but three possible explanations are
offered: (1) algal species are transferred by ballast
water from ships, (2) ocean currents deposit seed
populations, and (3) pollutants add nutrients to the
water. Many scientists believe that the G. breve
blooms in the Gulf of Mexico are a natural
phenomenon because they originate 10-50 miles
offshore in low-nutrient water (Fig. 19). This is
supported by records dating back to the 1500s of
blooms occurring offshore. Others speculate that,
although the currents in the Gulf of Mexico may
initiate a bloom with an upwelling of nutrients, the
actual bloom does not occur until the currents or pig. 19. Red Tide bloom off the west
winds carry the organisms into the nutrient-rich, Florida shelf. Photo credit: Dr. Frank
shallow, near-coastal waters. Muller-Karger, University of South
Florida.
24
-------
Sediment
Contaminants
Fig. 20. Houston Ship Channel surrounded by
petrochemical industries and shipping activities.
Photo credit: Galveston Bay National Estuary
Program.
Toxic substances and pesticides enter Gulf of
Mexico estuaries from industrial and
municipal discharges, urban and agricultural
runoff, accidental spills, and atmospheric
deposition (Fig. 20). These activities often
have adverse effects on estuarine habitat. For
example, the U.S. Coast Guard received an
annual average of 6217 notifications of oil or
chemical spills in Gulf of Mexico ports from
1991 to 1997. Chemicals that enter estuaries
are often bound to suspended particulate
matter that eventually deposits on the
sediment surface. Sediment deposition and
accumulation rates in an estuary depend
greatly on the rate of freshwater inflow and
access to flushing from the Gulf of Mexico.
Once deposited in the sediment, toxic chemicals may be available for uptake by benthic
organisms. Bioavailability is greatly dependent on the characteristics of the sediment,
including concentrations of total organic carbon and acid-volatile sulfide. Some chemicals
are acutely toxic, resulting in death of the animal; others may have chronic toxicity effects,
affecting growth or reproduction. Toxic chemicals can affect humans because they may
become biomagnified as they are stored in animal tissue and transferred through the food
chain. When sediment chemistry information is combined with sediment toxicity data and
benthic health indicators, a better assessment of overall sediment quality can be
accomplished.
Evaluation of the potential effects of contaminated sediments on estuarine organisms is
difficult because few applicable state or federal regulatory criteria exist to determine
"acceptable" sediment concentrations of all substances. Informal guidelines based on many
field and laboratory studies have been suggested, however. Guidelines such as effects range-
low (ER-L) and effects range-median (ER-M) values (Long et al. 1995) provide
environmental managers with benchmarks to determine if contaminated sediments have the
potential to adversely affect aquatic organisms. These (and other) guidelines benefit from the
weight of evidence afforded by large data sets associating sediment contaminant
25
-------
Sediment Contaminants
concentrations with biological effects, but suffer from a failure to incorporate the effects of
multiple chemicals in complex mixtures, as the chemicals exist in the environment. In
sediments in the Gulf of Mexico estuaries, EMAP measured polycyclic aromatic
hydrocarbons (PAHs; components of petroleum and produced by combustion processes),
polychlorinated biphenyls (PCBs; used in insulators and capacitors), aliphatic hydrocarbons
(e.g., alkanes which are abundant in crude oil), pesticides (e.g.,
dichlorodiphenyltrichloroethane [DDT], chlordane, dieldrin, endosulfan), organotins (e.g.,
tributyltin [TBT] found in anti-fouling paint) and trace metals (e.g., zinc, lead, mercury,
Number of Contaminants
>5 > ERL
> ERM
Fig. 21. Sites where contaminants (metals or organic) exceeded Long et al. (1995) ER-L or
ER-M guidelines (USEPA, EMAP Database for the Louisianian [1991-1994] and West
Indian [1995] Provinces).
cadmium, copper). EMAP reported that ER-L guidelines were exceeded for all of the major
groups of sediment contaminants, albeit at very low rates (<1% of area) for PAHs and PCBs.
There was a fairly even distribution of sites from the Florida panhandle to Corpus Christi
Bay, Texas, where contaminants exceeded ER-L or ER-M guidelines (Fig. 21). Based on the
percent area of each estuary that was contaminated, however, the majority of estuarine
systems in all gulf states were identified by EMAP as having fair to good sediment quality.
EMAP identified several estuaries as having predominately contaminated sediments. These
correspond well with those watersheds identified by the USEPA National Sediment Inventory
26
-------
Sediment Contaminants
Superfund Sites
Finalized sites
Proposed sites
Detailed sites
Construction completed sites
Fig. 22. Location of Superfund sites near coastal areas of the gulf states (USEPA).
as "areas of probable concern." Several USEPA Superfund sites are also located near heavily
industrialized estuaries, particularly Galveston Bay, Tampa Bay, and the Florida panhandle
(Fig. 22).
With one-half of the total chemical production and 30% of the total petroleum industry in the
U.S. located in and around Galveston Bay, Texas, this estuary provides a good example of
the impacts of urban and industrial sources on sediment quality. Galveston Bay has a history
of environmental problems as a result of rapidly escalating demands placed upon the bay's
resources. Sediment chemistry
analyses by USEPA's Region VI (R-
EMAP-TX) indicated that sites in East
Bay Bayou, Trinity Bay, the marinas,
and small lakes had as many as seven
contaminants exceeding ER-L
guidelines (Fig. 23). In East Bay
Bayou, several PAHs, including
fluorene and phenanthrene, exceeded
ER-L guidelines. At the marinas and
in Offats Bayou, copper and
chlordanes exceeded ER-L values.
Offats Bayou also had high levels of
lead, zinc, and DDT.
ERL Ranges
0
Station location
Fig. 23. Distribution of sites with sediment contaminants
greater than ER-L guidelines in Galveston Bay, TX (R-
EMAP, Texas, 1993).
27
-------
Habitat Change
Wetlands
Wetlands are the interface between the aquatic and terrestrial components of estuarine
systems. In the Gulf of Mexico, wetlands include both emergent (i.e., marshes and certain
forested scrub-shrub habitats) and submerged vegetated habitats (seagrasses; Fig. 24). These
habitats are critical to the life cycles of fish, shellfish, migratory birds, and other wildlife;
they also filter and process residential, agricultural, and industrial wastes, thereby improving
surface water quality, and they buffer coastal areas against storm and wave damage. An
estimated 95% of commercial fish and 85% of sport fish spend a portion of their lives in
coastal wetland and estuarine habitats. Adult stocks of commercially harvested shrimp in the
Gulf of Mexico are directly related to wetland quality and quantity (Turner and Boesch,
1988). Wetlands in the Gulf of Mexico region are being rapidly damaged or destroyed by
human activities (e.g., flood control, agriculture, waste disposal, real estate development,
shipping, commercial fishing, and oil and gas exploration and production) and natural
CO
2,500
2,000
1,500
o
ซ- 1,000
tf\
fli
u 500
0
D Florida
D Alabama
D Mississippi
D Louisiana
D Texas
Salt Marsh Fresh Forested Tidal Flats
Marsh
Fig. 24. Total acreage of dominant coastal wetland types by state based on U.S. Fish and Wildlife Service
wetland inventory maps (NOAA, 1991).
29
-------
Habitat Change
processes (e.g., rising sea level, sediment compaction and submergence, droughts, animal
"eat-outs," storms, and floods; Table 1).
Table 1. Primary causes of diminishing quality and acreage of coastal emergent
wetlands in the Gulf of Mexico by state (Duke and Kruczynski, 1992).
State
Texas
Louisiana
Mississippi
Alabama
Florida
Cause
Subsidence due to extraction of oil, gas, and fresh water
Navigation channels altering hydrodynamic flow
Natural subsidence
Reduced sediment deposition
Dredge and fill operations
Dredge and fill operations
Conversion to commercial and private developments
Total existing coastal wetland acreage and historical wetland loss estimates are the most
frequently cited indicators of wetland status. In a pilot study EMAP evaluated additional
indicators of wetland health that included the condition of individual plant species and soil
characteristics, in addition to acreage and loss estimates. These indicators were not measured
gulf-wide, however, and were not used for assessment in this report. Discrete estimates for
wetland acreage or loss for estuaries in the Gulf of Mexico were not available. Where
information on coastal wetland loss was available (e.g., for Louisiana) it was used; otherwise,
total wetland loss estimates were gathered for each gulf state. Total wetland loss (coastal and
inland) for the five gulf states from 1780 to 1980 was estimated to be 40 million km2
(approximately 50%; Fig. 25). Although agriculture is the leading cause of all wetland
losses, including coastal and inland, residential and commercial development accounted for
42% of estuarine wetland loss nationwide from 1985 to 1995. Between 1985 and 1995 the
southeastern U.S. lost the greatest area of wetlands (51% of national total), but the rate of
wetlands loss both nationally and in the gulf has slowed considerably.
Coastal emergent wetland loss for
Louisiana represents 67% of the
nation's total loss (177,625 ha or
438,911 acres) from 1978 to 1990
(Fig. 26). Much of this loss is related
to altered hydrology stemming from
navigation, flood control, and mineral
extraction and transport projects.
Most actual wetland loss is the result
of the indirect effects of these
projects, specifically the disruption of
flow and natural movement of water
and sediments rather than actual loss
due to erosion.
25
1780
1980
Fig. 25. Estimated total area of wetlands by state in 1780
and 1980 (Dahl, 1990; U.S. Fish and Wildlife Service).
30
-------
Habitat Change
Fig. 26. Changes in wetland area for coastal Louisiana based on National Wetland Inventory data and
Landstat TM Imagery compiled by USGS Baton Rouge Project Office.
Submerged Aquatic Vegetation
Submerged aquatic vegetation (SAV) species, or seagrasses, are particularly sensitive to light
and water quality. Seagrasses have an important ecological role in providing food for
waterfowl, manatees, and green sea turtles, and in providing habitat for many fish and
shellfish species. SAV also affects physical processes in estuaries, such as nutrient cycling,
sediment stability, and water turbidity. Changes in seagrass distribution, therefore, can
reflect the health of an estuary, and losses of seagrasses may be an indicator of water quality
problems. Seagrass habitat loss ranges from 20% to 100% over the last 50 years for most
estuaries in the northern Gulf of Mexico (Handley, 1995). This decline is related primarily to
coastal population growth and accompanying municipal, industrial, and agricultural
development, but some losses may also be attributed to natural causes (i.e., hurricanes,
storms, and salinity changes). Currently, 95% of the seagrass acreage in the Gulf of Mexico
is localized in estuarine areas of Florida and Texas. The NOAA Estuarine Eutrophication
Survey reported that the spatial coverage of SAV was very low to low (>0 to 25% coverage)
in 32 estuaries, particularly in the mixing zone. Spatial coverage was high in Apalachee Bay,
Florida and Laguna Madre, Texas. NOAA estimated that the spatial coverage of SAV in the
gulf was equivalent to 12-24% of the estuarine area. Where trends in SAV coverage were
observed, both increasing and decreasing trends were attributed to habitat alteration or to
changes in nonpoint and point sources of pollution and in hydrology.
31
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Biological
Integrity
Changes in biological communities may indicate a disruption of healthy environmental
conditions. Quantifying the condition of biological communities enables us to identify the
cumulative effects of pollution or habitat alteration. EMAP-E uses biological monitoring of
benthos and fish to evaluate estuarine condition. The National Marine Fisheries Service
(NMFS) monitors the productivity of fisheries to ensure the economic health of the fishing
industry. The U.S. Fish and Wildlife Service (USFWS) is responsible for tracking the
population status of waterfowl, which is an important indicator of wetland condition.
Monitoring the recovery of threatened and endangered species provides important
information about the success of management actions designed to protect the habitat of those
species.
Moderate
28%
Degraded
23%
Reference
49%
Benthos
The worms, clams, and crustaceans that
inhabit the bottom substrates of estuaries are
collectively called benthic macroinvertebrates
or benthos. These organisms play a vital role
in maintaining sediment and water quality,
and are an important food source for bottom-
feeding fish, shrimp, ducks, and marsh birds.
Benthos are often used as indicators of
perturbations in the estuarine environment
because they are relatively nonmobile, and
therefore cannot avoid environmental
problems. The response of benthic
communities to alterations in sediment and
water quality is relatively well understood and is often expressed as changes in community
structure, density, and diversity. Benthic population and community characteristics are
sensitive indicators of contaminant and dissolved oxygen stress, salinity fluctuations, and
disturbance and serve as reliable indicators of estuarine environmental quality. EMAP-E
developed a benthic index of environmental condition for estuaries that incorporates changes
in diversity and the populations of indicator species to distinguish degraded benthic habitats
from undegraded benthic habitats (Engle etal. 1994; Engle and Summers 1999). Using the
benthic index, 25% of the estuarine area in the Louisianian Province was determined to have
Fig. 27. Percent area of estuaries in the
Louisianian Province classified by the benthic
index as degraded (< 3), moderate (3-5), or
reference (> 5) (USEPA, EMAP Database for the
Louisianian Province, 1991 to 1994).
33
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Biological Integrity
degraded benthic resources from 1991 to 1994 (Fig. 27) (Macauley et al. 1999). When
examined on the level of an individual estuary (e.g., Pensacola Bay, FL), degraded benthic
resources were most often associated with sediment contaminants or hypoxia (Engle and
Summers 1998).
Pensacola Bay, an estuary in northwest Florida, has a sedimentation problem because of poor
flushing and high suspended sediment input from its tributaries. Evidence of problems in the
bay include low benthic diversity, decline of seagrasses and oyster populations, and
contaminated sediments, especially in the bayous. Pensacola Bay has predominantly muddy
sediments, dominated by polychaete and nemertean worms that are, in general, tolerant to
habitat disturbances. The benthic index identified 12 degraded sites located primarily in the
mainstem of Pensacola Bay and in the three bayous near Pensacola (Bayous Chico, Grande,
and Texar) (Fig. 28). Areas of Pensacola Bay have severely contaminated sediments, with as
many as 40 chemicals at concentrations greater than ER-L guidelines, especially in the
bayous. The benthic community is severely impoverished in the areas of the bay with low
sediment quality.
Benthic Index
Fig. 28. Areas in Pensacola Bay, Florida that were classified by the benthic index as
degraded (), moderate ( ), or reference () (Engle and Summers, 1998).
34
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Biological Integrity
Commercial and Recreational Fisheries
There is much public concern about the quality and abundance offish, especially
commercially and recreationally important species. Estuaries provide food, refuge from
predation, and habitat for a wide variety of fishes and invertebrates. Many of these species
are economically important and use various estuarine habitats to complete their life cycles.
Estuaries are especially important as nursery areas for many species during their early and
juvenile life stages. As a result, the economic viability of the commercial and recreational
fisheries of the Gulf of Mexico is also estuarine dependent. Tracking the status of fishery
resources is one step in the effort to build sustainable fisheries. The decline of fisheries may
be due to overfishing or habitat degradation. As the carrying capacity of an estuary declines,
the fish stocks which inhabit it can no longer support fishing levels that were previously
sustainable. Therefore, the status of fishery resources can be used as an indicator to assess
the suitability of estuarine habitat for sustaining those fisheries. The top four fisheries in the
Gulf of Mexico (menhaden, shrimp, oyster, blue crab) use estuaries extensively (Fig. 29).
The Gulf of Mexico yielded the nation's largest regional commercial fishery (excluding
Alaska) by weight in 1996, representing 33% of the national total by weight and 32% by
value. The total commercial harvest in the Gulf of Mexico was dominated by the landings
from Louisiana (Fig. 30). The Gulf of Mexico shrimp fishery is the largest and most valuable
in the United States, accounting for 69% of the total domestic harvest, with most of the
shrimp landings in Louisiana and Texas (Fig. 31). Shrimp are especially dependent on
estuaries, and the degradation of estuarine water quality and loss of gulf wetlands are
considered significant threats to this fishery.
Recreational fishing is also important to the economy of gulf states. Over 40% of the nation's
marine recreational fishing occurs in the Gulf of Mexico, with the highest number of anglers
fishing in Florida and Texas (Fig. 32). Although many of the recreational fish species are
exclusively offshore, some use estuaries for a major part of their life cycle. Speckled trout
(or spotted seatrout; Cynoscion nebulosus\ for example, spawns over seagrass beds but is
known to migrate offshore and red drum (Sciaenops ocellatd) spawns in estuaries where the
Metric Tons
9914 93324
27742
Million $
491615
400
] Shrimp n Blue Crab n Menhaden n Oyster
Texas Louisiana Mississippi Alabama Florida
Fig. 29. Landings in 1996 by weight and value for
the top four commercial species in the Gulf of
Mexico (National Marine Fisheries Service).
Fig. 30. Landings by weight and value of all
commercial species by state in the Gulf of Mexico in
1996 (National Marine Fisheries Service).
35
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Biological Integrity
Louisiana
Mississippi
Alabama
Florida
5,000
10,000 15,000
Metric Tons
20,000 25,000
Florida Gulf Coast
2,231
1,500
Fig. 31. Landings of shrimp by state and species in Fig. 32. Numbers in thousands of recreational
the Gulf of Mexico in 1996 (National Marine Fisheries anglers fishing in coastal waters in 1995 by state
Service). in the Gulf of Mexico (National Marine Fisheries
Service; Texas Parks & Wildlife).
young develop for 2-3 years before moving offshore.
The Red Drum Fishery
The drums (Family Sciaenidae) are characteristic of inshore fishes found in the northern Gulf
of Mexico and include important commercial and recreational species such as red drum (or
redfish), black drum (Pogonias cromis\ spotted seatrout, and Atlantic croaker. Most species
spawn in shallow offshore waters or at the entrance to a bay; the larvae enter estuaries, where
they spend one or more summers and take advantage of the greater availability of food and
protection which estuarine habitats afford. Some species, such as red and black drum, are
long-lived.
The red drum commercial fishery was closed to all harvest in U.S. Federal waters of the Gulf
of Mexico on January 1, 1988 (Fig. 33). Stock assessments indicated that red drum were
heavily fished prior to moving offshore to spawn and that those fish less than 12 years of age
were poorly represented in the
offshore spawning population. In
addition to the federal closure, states
enacted stringent measures to reduce
red drum mortality in inshore areas.
Red drum populations appear to be
responding to the management
measures, and, although all five
states have recreational bag limits
and slot limits that exclude large fish,
Texas has issued "Red Fish Tags"
that allow anglers to keep two large
fish per year.
Fig. 33. Commercial landings of red drum by weight and
value in the Gulf of Mexico from 1950 to 1995 (National
Marine Fisheries Service).
36
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Biological Integrity
Following the federal closure and
state regulatory actions on red drum,
black drum were accepted as a
substitute within the commercial
market (Fig. 34). This "new" fishery
added to the already existing pressure
on black drum and led the gulf states
to establish interim regulatory
measures. As a result, present harvest
levels are well below those which are
thought to negatively affect
recruitment and spawning stocks.
Fish Biomarkers
1955 1960 1965 1970 1975 1980 1985 1990 19!
Fig. 34. Commercial landings of black drum by weight
and value in the Gulf of Mexico from 1950 to 1995
(National Marine Fisheries Service).
An increased awareness of the adverse effects of environmental degradation on fish
populations has led many federal and state monitoring programs to include fish health
assessment (Blazer et al. 1994). Fish from contaminated waters often display pathological
conditions such as fin rot, skin ulcerations, skeletal abnormalities and epidermal growths. In
addition, these abnormalities may be indicators of health risk to birds, mammals, and even to
humans. Therefore, as an indicator of environmental conditions, fish abnormalities should
be of interest to resource and regulatory agencies as well as to the general public. Fish
biomarkers such as gross pathology, splenic macrophage aggregates, and skeletal anomalies
were investigated by EMAP in the Gulf of Mexico from 1991 to 1994.
The frequency and type of gross pathologies on fish taken from trawls in estuarine waters are
indicators of the overall condition offish populations. Field and laboratory studies have
shown an association between gross pathological disorders in fish and exposure to pollution.
Gross pathological disorders in fish
include tumors and lesions on the
skin, malformations of the eye, gill
abnormalities, and parasites. From
1991 to 1994, in the Louisianian
Province, EMAP examined 64,082
fish caught in trawls for external
gross pathological disorders. Gross
pathologies were observed on 408
fish, which gives a background
pathology incidence rate of 0.6%.
Of all pathologies observed, 61%
were parasites and 45% occurred in
menhaden (Brevoortictpcttronus;
Fig. 35). The majority of observed
pathologies (88.8%) occurred in
Atlantic croaker
19%
Atlantic bumper
Fig. 35. Distribution by species of the 408 fish with observed
gross pathological disorders (USEPA, EMAP Database for the
Louisianian Province, 1991 to 1994).
37
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Biological Integrity
Texas and Louisiana, with 47% of all pathologies found in fish from Galveston Bay, Texas.
Gross pathological abnormalities were more prevalent at sites with high sediment
contaminant concentrations (Fournie et al. 1996.)
Macrophage aggregates are a prominent feature offish spleen, kidney, and liver. Recent
studies suggest that the size and density of macrophage aggregates may be sensitive
histological indicators offish health and environmental quality (Blazer et al. 1994).
Although macrophage aggregates have been criticized as nonspecific, there is some evidence
that, when demersal fish are examined, increased size and density of macrophage aggregates
are associated with environmental contamination. One hundred ninety-one fish samples from
149 sites were examined for macrophage aggregates by EMAP-E from 1992 to 1994. Fish
from only five of these samples contained spleens with more than 40 macrophage aggregates
per square millimeter (Fig. 36). This incidence of relatively high macrophage aggregate
density represents a small percentage of the total number offish examined indicating a
localized effect of pollution on fish.
Fig. 36. Sites in the Gulf of Mexico where fish samples contained spleens with > 40 macrophage aggregates
per mm2 (USEPA, EMAP Database for the Louisianian Province, 1991 to 1994).
Coastal and Marine Birds
Gulf of Mexico estuaries provide necessary habitat for both migrant and resident coastal and
marine birds. Waterfowl, primarily ducks and geese, migrate to Gulf of Mexico feeding
grounds during winter to take advantage of the vast estuarine resources. Canvasback
(Aythya valisinerid), redhead (Aythya americana), and scaups (Aythya spp) and other divers
such as the ruddy duck (Oxyurajamaicensis), feed and congregate in open waters of
38
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Biological Integrity
1000
900
800
w 700
i 60ฐ
ง 500
| 400
300
200
100
Redhead
Breeding Population Estimates
estuaries, often clustered in dense rafts. An
estimated 80% of the redhead population
overwinters in the brackish to hypersaline
waters of Laguna Madre, Texas. Other
redhead wintering grounds in the Gulf of
Mexico include Chandeleur Sound, Louisiana
and Apalachee Bay, Florida. Redheads are
especially dependent on healthy SAV beds in
their wintering areas. If the decline in SAV
continues (over 50% of shoalgrass beds in
Laguna Madre have disappeared since the
1960's), the redheads may be forced to find
new wintering grounds. Healthy and stable
populations of waterfowl are indicators of
healthy estuarine and wetland conditions in
the Gulf of Mexico. Although redheads declined below their target population size of
760,000 during the 1980's, redheads currently exceed their target population size (Fig. 37).
1960
1970
1980
1990
2000
Fig. 37. Estimates of the number of redhead
ducks in the North American breeding population
from 1950 to 1996 (Smith, 1995; Federal Duck
Stamp, 1987-1988).
Wading birds of the coastal Gulf of
Mexico include the families, Ardeidae
(herons, egrets and bitterns),
Ciconiidae (storks), Gruidae (cranes),
and Threskiornithidae (ibis and
spoonbills). The most abundant
species in estuaries are tricolored
herons (Egretta tricolor) and snowy
egrets (Egretta thula). More than 80%
of the total number of breeding
tricolored and little blue herons
(Egretta caerulea) nest along the gulf
coast. Although the number of
colonies of wading birds on the gulf
coast is often less than the number of
colonies on the Atlantic Coast, the gulf
colonies are larger in number of birds,
accounting for a majority of the total
breeding population of wading birds
(Fig. 38). The wading birds listed in
Figure 38 prefer salt marshes and
other wetlands bordering coastal bays.
The North American Breeding Bird
Survey summarizes trends in wetland
breeding birds (e.g., herons) from
1966-1996. Significant decreasing
1ฃ=
Black skimmer
Gull-billed tern
Laughing gull
Least tern
0%
Great blue heror
Great egre
Little blue heror
Roseate spoonbill
Snowy egre
1
Marine birds
H I
f H
i r i
T C
i i i
/
20% 40% 60% 80% 100'
Wading birds
~^t
I I 1
I f 0
I I 0
I 0
I I 0
' /
)% 20% 40% 60% 80% 1000/
D Atlantic Florida DGulf |
/.
(,
Fig. 38. Breeding populations of wading birds and
seabirds common to the gulf coast showing the percent of
population located among the gulf, Florida, and Atlantic
coasts (U.S. Fish and Wildlife Service, 1988).
39
-------
trends in little blue heron populations were indicated for Alabama and Florida, while
significant increasing trends for other wading birds were indicated for all of the gulf states.
The most common marine birds along the gulf coast include laughing gulls (Larus atricilld),
terns (sub Family sterninae), and migrating sandpipers (Family Scolopacidae) and plovers
(Family Charadriidae). Laughing gulls are the only gull species that nest on the gulf coast,
and are the most abundant marine birds to nest in this region. The largest populations of
black skimmers (Rynchops niger) and gull-billed terns (Sterna niloticd) in the U.S. nest along
the gulf coast (Fig. 38). These birds utilize almost exclusively coastal bays and nearshore
waters for both nesting and feeding. The North American Breeding Bird Survey had little or
no trend information for these marine birds in the gulf states, however, laughing gulls were
listed as showing a significant increase in population from 1966-1996 in the southeast.
Threatened and Endangered Species
Degraded water quality, altered water flow, and loss of suitable habitat are the greatest threats
to aquatic species at risk of extinction. Efforts to minimize water pollution or restore natural
flow should contribute to the protection of threatened or endangered species. Because these
species are already at risk, they act as sentinels, providing us with early warnings of even
small perturbations in their environment. Charting their recovery also provides us with an
indicator of the success of management programs designed to ensure that these species have a
clean and safe habitat.
The Gulf sturgeon (Acipenser oxyrhynchus desotoi; Fig. 39) was listed as a threatened
subspecies on September 30, 1991. The Gulf sturgeon is an anadromous fish, migrating from
salt water into large coastal rivers. Historically, the Gulf sturgeon occurred in rivers from the
Mississippi River to the Suwannee River and in bays and estuaries from Florida to Louisiana.
Little is known about current population levels outside the Suwannee, Apalachicola and Pearl
Rivers but they are thought to have declined from historic levels. Although much of the
sturgeon's life is spent in fresh water, it utilizes bays and estuaries for feeding and migration.
Major threats to this rare, primitive species include physical barriers (e.g., locks and dams) to
spawning grounds, habitat loss, and poor water quality.
Fig. 39. Illustration of a Gulf sturgeon.
40
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Biological Integrity
The Florida manatee (Trichechus
manatus; Fig. 40) is currently listed as
an endangered species, although
ongoing efforts to protect manatee have
been successful and the Florida
population appears to be rebounding.
Manatee inhabit freshwater, brackish,
and marine waters throughout the gulf
coast, although the largest population is
in Florida. Along the gulf coast of
Florida, the principal summer habitats
of manatee are estuaries and riverine
grassbeds where they feed on
submerged, emergent, and floating
vegetation. Because manatee depend
on healthy estuarine habitat, shifts in
population counts may indicate
degradation of the coastal environment. The greatest human impacts on manatee survival
include recreational boat traffic and intensive coastal development, but some manatee
mortalities may also be attributed to natural causes (e.g., cold temperatures or red tide). In
1996, a record number of manatee (2,639) were counted in the January survey, but a record
number of deaths also occurred (416), with 151 deaths attributed to toxic red tide and 60 to
watercraft. The U.S. Fish and Wildlife Service's first 1997 survey reported an encouraging
population count of 2,229 manatee with a record high 1329 on the Florida west coast despite
the 1996 red tide deaths.
Fig. 40. Photograph of two manatee. Photo credit:
Homosassa Springs State Wildlife Park
The brown pelican (Pelecanus occidentalism
Fig. 41) is still listed as endangered in
Louisiana, Texas, and Mississippi, while stable
populations now thrive in Florida and Alabama.
Brown pelicans nest in colonies along the gulf
coast and feed primarily on fish from shallow
waters of estuaries. Because they depend on
high quality coastal habitat, declining trends in
brown pelican nesting populations may indicate
degradation of nesting substrate or fluctuations
in food supply. Brown pelican populations
declined sharply in the 1950's and 1960's,
primarily due to the ingestion offish
contaminated with pesticides like DDT. In the
1970's, the banning of DDT and listing the
pelican as an endangered species contributed to its successful rebound. The gulf coast
population, while still considered endangered, was recently estimated at 6,000 breeding pairs.
Fig. 41. Photograph of adult brown pelican.
Photo credit: Marcus G. Martin, University of
Minnesota.
41
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Biological Integrity
Several sea turtles are listed as
endangered in the Gulf of Mexico,
including the Kemp's ridley
(Lepidochelys kempii; Fig. 42),
green (Chelonia mydas),
loggerhead (Caretta caretta\
leatherback (Dermochelys
coriacea\ and hawksbill
(Eretmochelys imbricatd). Adults
of the Kemp's ridley sea turtle are
restricted to the Gulf of Mexico,
where their major non-nesting
habitat includes nearshore and
inshore waters (especially in
Louisiana) and salt marshes where
they feed on crabs and other
invertebrates. The entire
population of Kemp's ridley sea turtles has expanded its nesting range beyond the 5 miles of
beach in Tamaulipas, Mexico. In 1947 the population was estimated at 42,000 females;
currently, an estimated 1500 females return to nest and their numbers have been declining
each year. Major threats to this turtle have included overharvesting, shrimp nets, oil spills,
marine debris, and dredging. Currently the Mexican government has banned harvest of
Kemp's ridleys and instituted strict management and protection efforts while the National
Marine Fisheries Service has implemented regulations that require shrimp fisherman to use
turtle excluder devices in their trawls.
Fig. 42. Photograph of a baby Kemp's ridley sea turtle.
Photo credit: Bill Reaves, Texas Parks and Wildlife
Department.
42
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Public Health
Many pollutants found in Gulf of Mexico waters have the potential to produce acute and chronic
human health effects. Humans may be exposed to waterborne toxins or pathogens via two principal
pathways: consumption offish and shellfish and direct contact with water. The degree of human
health risk depends upon the specific characteristics of the pollutant, including its potential to reach
and thereby cause adverse impacts in humans. As an example, an advisory was issued by the
Louisiana Department of Health and Hospitals in June 1997 for Lake Pontchartrain. This advisory
was for swimming, consuming, inhaling spray or otherwise contacting the water after a toxic
cyanobacterial bloom spread over the lake following the opening of a spillway from the Mississippi
River.
Shellfish - Growing Waters
Shellfish resources in Gulf of Mexico estuaries range from those located only in brackish water to
those found mainly in salt marshes and inshore coastal areas, and include penaeid shrimp (Penaeus
spp.), blue crab (Callinectes sapidus), and oysters (Crassostrea virginicd). Oysters are important
ecologically because they have a major role in altering water clarity through filter-feeding and
because oyster reefs are vital habitats for other species. The Gulf of Mexico is the largest oyster-
producing region in the Nation, with 57% of the national total in 1996.
1,153
D Approved D Conditional D Restricted Prohibited
Shellfish-growing waters in the Gulf of
Mexico refer mainly to oyster-producing
waters. These are affected by urbanization
and may be closed to harvest because of
pollution. The National Shellfish Sanitation
Program (NSSP) classifies shellfish-growing
waters to protect public health. Shellfish-
growing waters are classified as approved,
conditionally approved, restricted, or
prohibited based on sanitary surveys that
identify actual pollution sources and evaluate
water quality data (Fig. 43). In cases where
water quality problems are the cause of
shellfish bed closures, this indicator could be
used to determine the area and extent of pollution. The acreage of shellfish-growing waters that are
harvest-restricted because of pollution can be used as an indicator of water quality to measure the
progress of improved coastal zone management efforts. Although the gulf region contains the most
classified shellfish-growing waters in the nation (6.3 million acres in estuaries in 1995), it also ranks
first in total acres of prohibited shellfish-growing waters. From 1990 to 1995 the total acres of
approved shellfish-growing waters decreased by 574,000 acres (Fig. 43). The top three pollution
sources affecting harvest limitation in 1995 were upstream sources, individual wastewater treatment
Fig. 43. Classified shellfish - growing waters in
thousand acres in the Gulf of Mexico (NOAA,
National Ocean Service).
43
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Public Health
plants, and wildlife. Commercial landings of oysters decreased from 1985 to 1990 but have
increased since 1990, especially in Louisiana and Texas (Fig. 44).
Landings (metric tons)
n
.
3
- :
n
ii
: : : - .
i i M M n M n
tit II
[
-
|
n
B
i I 1 \ \ I \ \ \ 11 I \ i
D Alabama Florida West Coast D Louisiana D Mississippi Tex
-
J i
as
-i
i n
r.
i
\l\\\\\\\\
Fig. 44. Commercial landings of oyster in the Gulf of Mexico by state from 1950 to 1995 (National
Marine Fisheries Service).
Contaminants in Fish and Shellfish
Seafood consumption advisories are designed to protect the public from the health risks of
consuming contaminated fish and wildlife. These advisories serve as a warning that high
concentrations of harmful chemicals (e.g., mercury and dioxins) have been found in local fish and
wildlife. Consumption advisories are useful as a benchmark because the number of waterbodies
added to the list each year is frequently a direct indicator of increasing environmental contamination.
As of 1997, Florida, Alabama, Louisiana, and Texas had fish consumption advisories in effect for
selected estuarine waters (Table 2).
Other federal monitoring programs that track the occurrence of chemicals in fish and shellfish tissue
include EMAP and the NOAA National Status and Trends Program Mussel Watch Project. Analysis
of chemical contaminants in the edible tissue of fish and shellfish provides information on the
bioaccumulation of contaminants released to the environment. This information could provide an
early warning for emerging problems that could affect the viability of estuaries. Guidance values
(U.S. Food and Drug Administration or international) for metal concentrations were exceeded in
catfish, croaker, and shrimp tissues analyzed by EMAP. In most cases, however, only a low
percentage of the fish populations showed elevated concentrations of trace metals (Fig. 45), and none
showed elevated levels of either pesticides or PCB's. The high concentrations of arsenic in catfish
(Fig. 45) may be an artifact of the chemical analysis that did not separate organic forms of arsenic
from inorganic forms. The NOAA Mussel Watch Project identified increasing trends, however, in
the concentrations of at least one target contaminant in oyster tissue from 21 of 55 monitored sites in
the gulf. Only six sites with increasing trends also had high concentrations of one or more metals.
44
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Public Health
Table 2. 1997 Active Fish Consumption Advisories for Gulf of Mexico Estuarine Waters (USEPA 1997).
Advisory Location
Florida marine waters
Gulf of Mexico, FL
Charlotte Harbor, FL
Tampa Bay, FL
Florida Keys, FL and Florida
Bay, FL
Alabama Coastal Waters
Bayou D'Inde, LA
Calcasieu River
Gulf of Mexico - off of LA
Coast
Lavaca Bay, TX
Houston ship channel, TX
Upper Galveston Bay, TX
Gulf of Mexico, TX
Pollutant
Mercury
Mercury
Mercury
Mercury
Mercury
Mercury
PCB's
Hexachlorobenzene
Hexachlorobutadiene
PCB's
Hexachlorobenzene
Hexachlorobutadiene
Mercury
Mercury
Dioxins
Mercury
Species
shark
King mackerel 33-39"
King mackerel > 39"
Spanish mackerel,
crevalle jack, spotted
seatrout
gafftopsail catfish,
crevalle jack, ladyfish,
Spanish mackerel
crevalle jack and spotted
seatrout
King mackerel >39"
King mackerel <39"
fish and shellfish
fish
King mackerel < 39"
King mackerel > 39"
fish and crab
catfish and blue crab
King mackerel
Population affected1
Restricted general
Restricted special
Restricted general
Restricted special
No consumption general
Restricted general
Restricted special
Restricted general
Restricted special
Restricted general
Restricted special
No consumption general
Restricted general
No consumption special
Restricted general
Limited consumption
Restricted general
Restricted special
No consumption general
Fishing ban
No consumption special
Restricted general
Restricted general
Restricted special
1 Terms for Population Affected:
Restricted - consumption should be limited to one meal per week; this varies by state
No consumption - fish should not be consumed at all by the population affected
General - population, in general
Special - population, special high-risk groups (e.g., children and women of child-bearing age)
45
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Public Health
Fish Kills
The assessment of mortalities offish, or fish kills, can
be used by environmental managers to determine
areas of concern. Large numbers of dead or dying
fish in estuaries are an aesthetic nuisance as well as a
health threat. Fish kills may be indicators of natural
phenomena like sudden changes in temperature
("freeze kills"), oxygen depletion resulting from
sustained periods of hot weather coupled with low-
flow conditions, or red tide. Human activities such as
accidental toxic chemical spills, toxins released in
wastewater, or nutrient enrichment may also
contribute to fish kills. Most states are mandated to
respond to fish kill events, to determine the most
probable cause, and to compile summaries
offish kills. NOAA compiled a nationwide
database of fish kills in coastal waters from
1980-89. Results indicated that there was
no trend in fish kill events during this time
(Fig. 46), but that the majority offish kill
events occurred during the summer months
and were caused by hypoxia (Fig. 47). A
national "hot spot" for fish kills was in
Texas, where Galveston County had the
highest number offish killed and Galveston
Bay had the most reported events.
Currently, an association of Federal and
State agency personnel are creating a
network for Gulf of Mexico coastal waters
to report fish kill events (Gulf of Mexico
Aquatic Mortality Network or GMNET).
GMNET's mission is (1) to enhance
cooperation among the Gulf states so that fish kill data
are collected and reported in a timely and consistent
manner, and (2) to determine if fish kill events can be
used as an indicator of environmental perturbation in
estuaries.
Metals in Tissue
FDA Exceedances
Fig. 45. Percent of sampled population for
target species with tissue concentrations of
metals that exceeded FDA guidelines (USEPA,
EMAP Database for the Louisianian
Province, 1991 to 1994).
80 81 82 83
84 85 86
Year
88 89
I Numbers -
-Events
Fig. 46. Number of fish kill events and number of fish
killed in Gulf of Mexico coastal waters from 1980 to 1989
(NOAA/ORCA 1991).
Number of Fteh-KlH Events
OH
46
Fig. 47. Percent of all fish kill events
in Gulf of Mexico coastal waters from
1980 to 1989 that were caused by low
dissolved oxygen, temperature,
storms, or waste water
(NOAA/ORCA 1991).
-------
Ecological
Report Card
In a letter addressed to participants attending a National Environmental Monitoring and
Research Workshop at the Smithsonian Institution on September 25, 1996, Vice-President
Gore challenged federal agencies to "work with the scientific community and other interested
parties to produce a 'report card' on the health of our Nation's ecosystems by 2001. This
report card should establish an environmental baseline to evaluate the status of our
ecosystems." Partly in response to this challenge, EMAP's research strategy includes
regional-scale geographic assessments that will result in "State of the Region" reports.
Geographic assessments will use ecological indicators to describe the status and trends in the
condition of environmental resources within a region and to evaluate the probable causes of
the observed effects.
This report takes one step in assessing the health of Gulf of Mexico estuaries. This
assessment may serve as a baseline for conditions in gulf estuaries. Progress to date can be
estimated and the effects of future management decisions can be gauged by comparing future
conditions to the data presented in this report.
The rating of each indicator is summarized separately using a green to red (rank scores of 1 to
5) color scheme where green means good or no problem, and red means poor or severe
problem. Where possible, rankings were based on the percent area of estuaries that were
affected by levels of one or more indicators that described "problem" conditions (see final
report card at the end of this chapter for a key to the color scheme).
I Nutrients
FL
I
AL
I
MS
LA
I
TX
I Gulf 1
Eutrophication is potentially one of the most critical problems facing gulf coastal ecosystems.
Excess nitrogen enters gulf estuaries via fertilizer runoff from agricultural and residential
land, animal manure, and atmospheric deposition. The gulf region has the highest number of
wastewater treatment plants and the most land devoted to agriculture with the most applied
fertilizer. Many gulf estuaries show evidence of pre-eutrophic or eutrophic conditions. The
goal of State and Federal agencies responsible for managing coastal ecosystems is to identify
potential problems and take preventive actions before they become a reality. Four indicators
of nutrient enrichment were used to assess the overall nutrient status of estuaries: the NOAA
Estuarine Eutrophication Survey, state 305(b) assessments of nitrogen and chlorophyll levels,
and Rabalais' (1992) evaluation of nutrient increases. Nutrient problems ranged from
minimal in Alabama to definite problems in Louisiana and Texas with overall moderate
47
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Ecological Report Card
problems throughout the gulf.
I Dissolved Oxygen I FL I AL I MS I LA I TX I Gulf I
Dissolved oxygen (DO) in the Gulf of Mexico has received much press recently due to the
large area of hypoxia located on the continental shelf off the Louisiana coast. Estuarine
hypoxia, on the other hand, is less understood except at a local level (e.g., the "jubilee"
phenomenon in Mobile Bay). Low DO in estuaries may be attributed to natural cycles of
stratification, metabolism, seasonal storm events, and depth/tide regimes. Low DO is often
exacerbated by the anthropogenic effects of nutrient enrichment habitat modification, and
channelization. Using EMAP and NOAA data and Rabalais' (1992) assessment of oxygen
depletion, gulf estuaries ranked as fair overall, with most of the estuaries with persistent low
DO occurring east of the Mississippi River.
1 Sediment
1 Contaminants
FL
AL
MS LA
TX
Gulf
Long et al.'s (1995) ER-L and ER-M values provide guidance for environmental managers to
identify sediments with a possible or probable likelihood of causing adverse effects to the
biota. Using these and other guidelines in an assessment of contaminants in gulf estuaries,
Engel and Evans (1997) concluded that "the coastal Gulf of Mexico is not broadly at risk
from persistent chemical contaminants." We compared the EMAP data to these guidelines
and also concluded that estuarine sediments in the Gulf of Mexico, are in fair condition
overall with respect to contaminants. The few "hot spots" that have been identified by large-
scale monitoring programs seem to be localized to shipping channels and point sources.
I Wetlands I FL | AL | MS I LA | TX | Gull I
We were unable to obtain standardized data on coastal wetland loss rates throughout the Gulf
of Mexico region. The National Oceanic and Atmospheric Administration reported in 1991
that although the gulf had the most acreage of coastal wetlands in the United States, the
region also had the highest rate of wetland loss. Total loss of wetlands (coastal and inland) in
the gulf states ranged from 41% in Louisiana to 54% in both Florida and Mississippi from
1780 to 1980. Seagrass habitat loss ranged from 20% to 100% for most gulf estuaries over
the past 50 years. The acreage of coastal wetlands has continued to diminish since the 1950's
in all states, although the rate of wetland loss has slowed (e.g., from 42 mi2/yr during the
1970's to 25 mi2/yr in the 1990s in Louisiana). Most coastal wetlands are lost to residential
and commercial development although, in Louisiana, coastal wetlands are often destroyed by
hydrologic alterations. The high rate of coastal wetland loss in the Gulf of Mexico is mostly
the result of man's influence.
I Benthos I FL I AL I MS I LA I TX I Gulf I
EMAP-E collected benthic samples from northern gulf estuaries from 1991 to 1994. A
benthic index of estuarine condition was developed by EMAP-E that can be used to indicate
whether the benthic communities are similar to known degraded communities, known
reference communities, or are somewhere between these two extremes. Twenty-three percent
of the estuarine area in the northern Gulf of Mexico (excluding Tampa Bay to Florida Bay)
had degraded benthic communities. When the condition of the benthos is examined on a
48
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Ecological Report Card
local level, degraded benthic communities are often associated with sediment contaminants
or hypoxia.
Fish/Shellfish
Landings
FL
AL
MS
LA
TX
Gulf
The top four fisheries in the Gulf of Mexico (menhaden, shrimp, oyster, blue crab) use
estuaries extensively. Trends in commercial landings vary among the gulf states but are, in
general, stable. The shrimp fishery in the gulf, for example, accounts for 69% of the
domestic harvest of shrimp. Shrimp landings are stable in Florida, Alabama, and Mississippi,
but they have been decreasing in Louisiana and Texas. Degraded water quality and loss of
wetlands have been cited as possible causes of the declines in shrimp fisheries in these states.
A fishery management success story can be seen in the history of the red drum. Following a
severe population crash due to overfishing in the late 1980's, the red drum fishery was closed
to all commercial harvest. A decade later, however, the red drum population in the gulf is
recovering, and limited fishing is now allowed in all gulf states.
I Fish Biomarkers I FL I AL I MS I LA I TX I Gulf ~l
Fish health assessments were made by EMAP-E in the northern gulf estuaries (excluding
Tampa to Florida Bay) by examining fish for gross pathological disorders and splenic
macrophage aggregates. Incidences offish pathologies and macrophage aggregates occurred
at a higher rate in Alabama and Texas than in the other gulf states but were, in general,
confined to certain estuaries. Most of the pathologies observed were parasites, and most
occurred in menhaden. High rates of gross pathological abnormalities and high densities of
macrophage aggregates may be associated with environmental contamination.
Coastal and Marine
Birds
FL
AL
MS
LA
TX
Gulf |
Gulf of Mexico estuaries and wetlands provide essential habitat for migratory and resident
birds. Waterfowl use these ecosystems as winter feeding grounds. Resident wading birds
and marine birds rely on estuaries and wetlands for nesting and feeding. In general, gulf
estuaries and wetlands support large, healthy, stable populations of waterfowl and other
coastal birds.
I Threatened Species I FL I AL I MS I LA I TX I Gulf ~l
Many threatened and endangered species inhabit the gulf states but only four use estuaries
almost exclusively: brown pelican, Gulf sturgeon, manatee and Kemp's ridley sea turtle.
These species' populations are stressed primarily because of degraded water quality and
habitat alterations. The brown pelican is stable in Florida and Alabama and, while population
numbers are low elsewhere, there is some evidence that they are increasing. There is little
information about the population stability of the Gulf sturgeon outside of Florida, and the
manatee is found routinely only in Florida. Manatee numbers are still low but appear to be
recovering slowly. The Kemp's ridley sea turtle population has been steadily declining since
the 1940's and is currently estimated to have only a thousand nesting females.
49
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Ecological Report Card
I Shellfish Bed Closures I FL I AL T
MS
I
LA
I
TX
I Gulf 1
Although the gulf region contains the most classified shellfish-growing waters in the U.S.
(6.3 million acres in 1995), this region also has the most acreage of waters that are restricted
or prohibited for shellfish harvest. The percent of waters among the gulf states that were
harvest-restricted from 1985 to 1995 ranged from 24% to 43% with increases in restricted
waters over that time from 4% to 65%. Gulf waters lost 574,000 acres of approved shellfish-
growing waters between 1990 and 1995, mostly due to pollution from upstream sources and
wastewater treatment plants.
I Tissue Contaminants I FL | AL |
MS
_L
LA
_L
TX
_L
Gulf
J
Environmental contaminants found in the edible tissue offish and shellfish could potentially
pose a threat to human health. Seafood consumption advisories were issued in Florida,
Alabama, Louisiana, and Texas in 1997. EMAP-E analyzed 718 composite fish/shellfish
samples for chemical contaminants. Comparing the results to FDA and international
consumption guidelines yielded a low percentage offish/shellfish with elevated
concentrations of contaminants.
Priority Ecological Indicators
Nutrients *
Dissolved oxygen *
Sediment contaminants *
Wetland *
Benthos *
Fish/shellfish landings
Fish biomarkers
Coastal and marine birds
Threatened species
Shellfish closures *
Fish tissue contaminants
FL
AL
MS
LA
TX
Gulf
* Key to color scheme where % area indicates the best estimate
of % area affected by adverse condition levels of the indicator.
Color
% area
0-5%
> 5-10%
>10-25%
>25-35%
>35%
Subjective rank
good; no problem
good-fair; minimal problem
fair; moderate problem
fair-poor; definite problem
poor; severe problem
50
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Ecological Report Card
The final product of this report is a report card that represents the best estimates of the extent
of ecological conditions based on the most recent available data. For the gulf estuaries
overall, most indicators ranked in fair condition. Minimal or no problems were observed for
fish and bird populations gulf-wide. Wetland loss and shellfish bed closures were rated as
definite or severe problems for almost all gulf states and these indicators presented the most
severe ecological concerns for gulf estuaries. Estuaries on the Florida gulf coast had
moderate problems identified by most of the indicators and, of all states, Florida rated most
similarly to the gulf overall. Alabama rated good to fair for most of the indicators, with
problems indicated by dissolved oxygen and fish biomarkers. Mississippi rated good to fair
for all indicators except wetland loss. Louisiana and Texas had definite problems with
nutrients. Fish tissue contaminants were a definite problem in Louisiana while degraded
benthic communities and fish health were indicated as problems in Texas.
The mix of colors in the report card suggest that estuaries in the Gulf of Mexico have some
significant environmental problems but that the extent of these problems varies among the
gulf states. There has been some improvement in the condition of estuaries since the Clean
Water Act was passed as indicated by the good condition of some estuarine fauna and the
relatively moderate problems with water quality and contaminants. The orange and red areas,
however, indicate that effective management and protection of estuaries must continue in the
Gulf of Mexico. Special attention should be directed toward stemming the loss of coastal
wetlands gulf-wide and improving the quality of wastewater and other effluents in order to
increase the acreage of shellfish beds that are approved for harvest.
51
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52
-------
Data Sources
Introduction
"National Estuary Program: Bringing our Estuaries New Life" located at the website for U.S.
EPA, Office of Water, Office of Wetlands, Oceans, and Watersheds, National Estuary
Program.
)://www.ei)a.gov/OVVO'W/estuaries/net).I
"National Estuarine Research Reserve System (NERRS)" located at the web site for the
NERRS centralized data management office.
http://inlet.geol.sc.edu/cdmohoine.htiiil
Estuaries and Their Value
Weber, M., R.T. Townsend, and R. Bierce. 1992. Environmental Quality in the Gulf of
MexicoA Citizen's Guide. Center for Marine Conservation: Washington, D.C. 132 p.
"An Introduction to Estuaries" and the Estuary-Net Project located at the web site for
National Estuarine Research Reserve System.
http://iniet.geol.sc.edu/nerrsintro. html
"Estuary Facts" located at the web site for Restore America's Estuaries.
http://www.estuairies.org/
National Oceanic and Atmospheric Administration. 1990. Estuaries of the United
StatesVital Statistics of a National Resource Base. National Oceanic and Atmospheric
Administration, National Ocean Service, Rockville, MD. 79 p.
"Commercial and Recreational Fisheries" located at the web site for NOAA, National Marine
Fisheries Service, Fisheries Statistics and Economics Division.
h //'ir e in o r a. s s p. in m fs. g o v /
Waterborne Commerce of the United States, 1995. Water Resources Support Center, U.S.
Army Corps of Engineers, Fort Bluoir, VA.
53
-------
Melancon, J.M., C.L. Nixdorff, R.C. Bowser, and C. Yu. 1997. Gulf of Mexico Outer
Continental Shelf Daily Oil and Gas Production Rate Projections from 1996 through 2000.
MMS 97-0006. Minerals Management Service, Gulf of Mexico OCS Regional Office, New
Orleans, LA.
Lore, G.L., J.P. Brooke, D.W. Cooke, RJ. Klazynski, D.L. Olson, and K.M. Ross. 1996.
Summary of the 1995 Assessment of Conventionally Recoverable Hydrocarbon Resources of
the Gulf of Mexico and Atlantic Outer Continental Shelf. MMS 96-0047. Minerals
Management Service, Gulf of Mexico Region, New Orleans, LA.
Population Distribution
Culliton, T.I, M.A. Warren, T.R. Goodspeed, D.G. Remer, C.M. Blackwell, and J.J.
McDonough, IE. 1990. 50 Years of Population Change along the Nation's Coasts, 1960-
2010. U.S. Department of Commerce, National Oceanic and Atmospheric Administration,
National Ocean Service, Silver Spring, MD. 41 p.
Culliton, T.J., JJ. McDonough, HI, D.G. Remer, and D.M. Lott. 1992. Building along
America's Coasts. 20 Years of Building Permits, 1970-1989. U.S. Department of
Commerce, National Oceanic and Atmospheric Administration, National Ocean Service,
Rockville, MD. 49 p.
"Population Estimates of the U.S., Coastal Regions and States by Coastal Region" located at
the web site for the U.S. Bureau of the Census.
"Population and Development in Coastal Areas - Population Estimates for Estuarine and
Coastal Drainage Areas (ED As/CD As)" located at the web site for NOAA's ORCA
Information Service.
Consequences of Human Usage
U.S. EPA. 1994. Freshwater Inflow Action Agenda for the Gulf of Mexico. EPA/800/B-
94/006. U.S. Environmental Protection Agency, Office of Water, Gulf of Mexico Program,
Stennis Space Center, MS.
54
-------
Da fa Sources
Land Use
National Oceanic and Atmospheric Administration. 1990. Estuaries of the United States:
Vital Statistics of a National Resource Base. National Oceanic and Atmospheric
Administration, National Ocean Service, Rockville, MD. 79 p.
"AVHRR Vegetation Index" - compiled from data on CD-ROM. North American
Composite: an AVHRR 1 km North American Continent Data Set for Global Change
Monitoring. 1992. U. S. Geological Survey, EROS Data Center, National Mapping
Division.
Natural Habitat Characteristics
NOAA. 1990. Estuaries of the United States - Vital Statistics of a National Resource Base.
National Oceanic and Atmospheric Administration, National Ocean Service, Rockville, MD.
79 p.
U.S. EPA, EMAP-E Database for the Louisianian (1991-1994) and West Indian (1995)
Provinces. U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL.
Freshwater Inflow
U.S. EPA. 1994. Freshwater Inflow Action Agenda for the Gulf of Mexico. EPA/800/B-
94/006. U.S. Environmental Protection Agency, Office of Water, Gulf of Mexico Program,
Stennis Space Center, MS.
Cross, R.D. and D.L. Williams (eds.) 1981. Proceedings of the National Symposium on
Freshwater Inflow to Estuaries. FWS/OBS-81/04. U.S. Fish and Wildlife Service,
Biological Services Program, Washington, DC.
Longley, W.L. (ed.) 1994. Freshwater Inflows to Texas Bays and Estuaries: Ecological
Relationships and Methods for Determination of Needs. Texas Water Development Board,
Austin, TX.
Water Quality
Hunsaker, C.T. and D.E. Carpenter. 1990. Environmental Monitoring and Assessment
Program Ecological Indicators. EPA/600/3-90/060. U.S. Environmental Protection Agency,
Office of Research and Development. Washington, D.C.
55
-------
U. S. EPA. 1996. Environmental Indicators of Water Quality in the United States.
EPA/841-R-96-002. U.S. Environmental Protection Agency, Office of Water, Washington,
D.C.
Strategic Assessment of Florida's Environment (SAFE)
Florida Assessment of Coastal Trends (FACT), Florida Department of Community Affairs,
Florida Coastal Management Program.
Pensacola Bay Ecosystem Management Plan: Environmental Indicator System at the web site
for Florida Department of Environmental Protection, Northwest District.
U.S. EPA. 1995. 1994 National Water Quality Inventory Report to Congress. EPA/841/R-
95/005 U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
U. S. EPA. 1997. Address by Vice President, Al Gore, on the 25th Anniversary of The Clean
Water Act. October 18, 1997, The White House, Office of The Vice President.
"The Quality of our Nation's Water: 1996" located at the web site for the U.S. Environmental
Protection Agency.
"The Quality of our Nation's Water: 1996 State Fact Sheets" located at the web site for the
U.S. Environmental Protection Agency.
The State of Texas Water Quality Inventory, 13th Edition, 1996. Prepared pursuant to Section
305(b) Federal Clean Water Act by the Texas Natural Resource Conservation Commission,
Austin, TX. SFR-50.
1996 Louisiana Water Quality Inventory. Prepared pursuant to Section 305(b) Federal Clean
Water Act by the Louisiana Department of Environmental Quality, Water Quality
Management Division, Baton Rouge, LA.
State of Mississippi Water Quality Assessment 1996. Prepared pursuant to Section 305(b)
Federal Clean Water Act by the Mississippi Department of Environmental Quality, Office of
Pollution Control, Jackson, MS.
56
-------
Water Quality Report to Congress for Calendar Years 1994 & 1995, June 1996. Prepared
pursuant to Section 305(b) Federal Clean Water Act by the Alabama Department of
Environmental Management, Montgomery, AL.
1996 Water-Quality Assessment for the State of Florida, Section 305(b) Main Report.
Prepared pursuant to Section 305(b) Federal Clean Water Act by the Florida Department of
Environmental Protection, Tallahassee, FL.
Eutrophication
USEPA. 1998. Condition of the Mid-Atlantic Estuaries. EPA 600-R-98-147. U.S.
Environmental Protection Agency, Office of Research and Development, National Health and
Environmental Effects Laboratory, Atlantic Ecology Division, Narragansett, RI.
NOAA. 1997. NOAA's Estuarine Eutrophication Survey, Volume 4: Gulf of Mexico
Region. Silver Spring, MD: Office of Ocean Resources Conservation and Assessment
(ORCA). 77 p.
Rabalais, N.N. 1992. An Updated Summary of Status and Trends in Indicators of Nutrient
Enrichment in the Gulf of Mexico. Report to Gulf of Mexico Program, Nutrient Enrichment
Subcommittee. Publication No. EPA/800-R-92-004, U.S. Environmental Protection Agency,
Office of Water, Gulf of Mexico Program, Stennis Space Center, MS. 421 p.
NOAA. 1990. Estuaries of the United States - Vital Statistics of a National Resource Base.
National Oceanic and Atmospheric Administration, National Ocean Service, Rockville, MD.
79 p.
U.S. EPA. 1994. Nutrient Enrichment Action Agenda for the Gulf of Mexico. EPA/800-B-
94-004. U.S. Environmental Protection Agency, Office of Water, Gulf of Mexico Program,
Stennis Space Center, MS. 161 p.
Puckett, LJ. 1994. Nonpoint and Point Sources of Nitrogen in Major Watersheds of the
United States. Water-Resources Investigations Report 94-4001. U.S. Geological Survey,
National Water Quality Assessment Program, Reston, VA.
U.S. EPA, EMAP-E Database for the Louisianian (1991-1994) and West Indian (1995)
Provinces. U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL.
57
-------
Macauley, J.M., J.K. Summers, and V.D. Engle. 1999 Estimating the Ecological Condition
of the Estuaries of the Gulf of Mexico (1991-1994): Statistical Summary. Environmental
Monitoring and Assessment (in press).
ADEM. 1997. A Report on the Condition of the Estuaries of Alabama in 1993-1995: A
Program in Progress. Alabama Monitoring & Assessment Program - Coastal. Alabama
Department of Environmental Management, Mobile Field Office, Mobile, AL.
Harmful Algal Blooms
"The Harmful Algae Page" located at the web site for the National Office for Marine
Biotoxins and harmful Algal Blooms, Woods Hole Oceanographic Institution, Woods Hole,
MA.
"HAB Events in the U.S." located at the web site for the National Office for Marine
Biotoxins and Harmful Algal Blooms, Woods Hole Oceanographic Institution, Woods Hole,
MA.
"Red Tide Bloom off west Florida shelf," located at the web site for the University of South
Florida, CZCS Images.
"ECOHAB - Ecology and Oceanography of Harmful Algal Blooms" located at the web site
for the Florida Marine Research Institute.
"What is Red Tide?" located at the web site for Solutions to Avoid Red Tide (START),
Longboat Key, FL.
"Frequently Asked Questions about Red Tide" located at the web site for Texas Parks and
Wildlife, Austin, TX.
Sediment Contaminants
U.S. EPA, EMAP-E Database for the Louisianian (1991-1994) and West Indian (1995)
Provinces. U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL.
58
-------
Coast Guard Notifications by Unit located at the web site for The National Response Center.
U.S. EPA. 1994. Toxic Substances and Pesticides Action Agenda for the Gulf of Mexico.
EPA/800/B-94/005. U.S. Environmental Protection Agency, Office of Water, Gulf of
Mexico Program, Stennis Space Center, MS.
Long, E. R., D. D. MacDonald, S. L. Smith, and F. D. Calder. 1995. Incidence of adverse
biological effects within ranges of chemical concentrations in marine and estuarine
sediments. Environmental Management 19:81-97.
"National Priorities List (NPL) Sites in the United States" located at the web site for U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Superfund.
Shipley, F.S. and R.W. Kiesling (eds.) 1994. The State of the Bay: A Characterization of the
Galveston Bay Ecosystem. The Galveston Bay National Estuary Program Publication
GBNEP-44. 232 p.
U.S. EPA. 1993. R-EMAP Regional Environmental Monitoring and Assessment Program.
EPA/625/R-93/012. U.S. Environmental Protection Agency, Office of Research and
Development, Cincinnati, OH.
U.S. EPA. R-EMAP-TX Database for Galveston Bay, 1993. U.S. Environmental Protection
Agency, Region 6, Dallas, TX.
Engel, D.W. and D.W. Evans. 1997. Assessment of Contaminants in Sediments of the
Coastal Gulf of Mexico and Potential For Impact on Living Marine Resources. Draft Report
to U. S. Environmental Protection Agency, Gulf of Mexico Program, Stennis Space Center,
MS.
Habitat Change
NOAA. 1991. Coastal Wetlands of the United States: An Accounting of a Valuable
National Resource. National Oceanic and Atmospheric Administration, National Ocean
Service, Rockville, MD. 59 p.
Barras, J.A., P.E. Bourgeois, and L.R. Handley. 1994. Land Loss in Coastal Louisiana 1956-
90. National Biological Survey, National Wetlands Research Center Open File Report 94-01.
59
-------
Data Sources
Johnston, J.B., M.C. Watzin, J.A. Barras, and L.R. Handley. 1995. Gulf of Mexico Coastal
Wetlands: Case Studies of Loss Trends. In: LaRoe, E.T., et al. (eds.) Our Living Resources:
a Report to the Nation on the Distribution, Abundance, and Health of U.S. Plants, Animals,
and Ecosystems. U.S. Department of the Interior, National Biological Service, Washington,
D.C. p. 269-272.
Duke, T. and W.L. Kruczynski. 1992. Status and Trends of Emergent and Submerged
Vegetated Habitats, Gulf of Mexico, U.S.A. EPA/800-R-92-003. U.S. Environmental
Protection Agency, Office of Water, Gulf of Mexico Program, Stennis Space Center, MS.
161 p.
Dahl, Thomas E. 1990. Wetlands Losses in the United States 1780's to 1980's. U.S.
Department of the Interior, Fish and Wildlife Service, Washington, D.C.
Status and Trends of Wetlands in the Conterminous United States, 1985-1995. Draft report.
U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C.
Turner, R.E. and D.F. Boesch. 1988. Aquatic Animal Production and Wetland
Relationships: Insights Gleaned Following Wetland Loss or Gain. In: The Ecology and
Management of Wetlands. Vol. 1. Ecology of Wetlands. Timber Press: Portland, OR. p. 25-
39.
U.S. EPA. 1994. Habitat Degradation Action Agenda for the Gulf of Mexico. EPA/800/B-
94/002. U.S. Environmental Protection Agency, Office of Water, Gulf of Mexico Program,
Stennis Space Center, MS.
Handley, L.R. 1995. Seagrass Distribution in the Northern Gulf of Mexico. In: LaRoe, E.T.,
et al. (eds.) Our Living Resources: a Report to the Nation on the Distribution, Abundance,
and Health of U.S. Plants, Animals, and Ecosystems. U.S. Department of the Interior,
National Biological Service, Washington, D.C. p. 273-275
Deegar, L.A., J.W. Day, and J.G. Gosselink. 1986. Relationships among physical
characteristics, vegetation distribution, and fisheries yield in Gulf of Mexico Estuaries. In:
D.A. Wolfe (ed.) Estuarine Variability. Academic Press, Inc.; Orlando, Florida.
NOAA. 1997. NOAA's Estuarine Eutrophi cation Survey, Volume 4: Gulf of Mexico
Region. Silver Spring, MD: Office of Ocean Resources Conservation and Assessment
(ORCA). 77 p.
60
-------
Biological Integrity
Engle, V.D., J.K. Summers, G.R. Gaston. 1994. A Benthic Index of Environmental
Condition of Gulf of Mexico Estuaries. Estuaries 17:372-384.
Engle, V.D. and J.K. Summers. 1998. Determining the Cause of Benthic Condition.
Environmental Monitoring and Assessment 51:381-397.
Engle, V.D. and J. K. Summers. 1999. Refinement, Validation, and Application of a
Benthic Condition Index for Northern Gulf of Mexico Estuaries. Estuaries, (in press).
Macauley, J.M., J.K. Summers, and V.D. Engle. 1999. Estimating The Ecological Condition
of The Estuaries of The Gulf of Mexico (1991-1994): Statistical Summary. Environmental
Monitoring and Assessment (in press).
U.S. EPA, EMAP-E Database for the Louisianian Province, 1991-1994. U.S. Environmental
Protection Agency, Gulf Ecology Division, Gulf Breeze, FL.
"Commercial and Recreational Fisheries" located at the web site for NOAA, National Marine
Fisheries Service, Fisheries Statistics and Economics Division.
"Texas Recreational Fishery Statistics" located at the web site for Texas Parks and Wildlife.
"The Red Drum in Texas" and "Status of the Fishery" located at the web site for Texas Parks
and Wildlife.
U.S. EPA. 1994. Living Aquatic Resources Action Agenda for the Gulf of Mexico.
EPA/800/B-94/007. U.S. Environmental Protection Agency, Office of Water, Gulf of
Mexico Program, Stennis Space Center, MS. July, 1994.
Fournie, J.W., J.K. Summers, and S.B. Weisberg. 1996. Prevalence of Gross Pathological
Abnormalities in Estuarine Fishes. Transactions of the American Fisheries Society 125:581-
590.
Blazer, V.S., D.E. Facey, J.W. Fournie, L.A. Courtney, and J.K. Summers. 1994.
Macrophage Aggregates at Indicators of Environmental Stress. Modulators of Fish Immune
Response 1:169-185.
61
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Smith, G.W. 1995. A Critical Review of the Aerial and Ground Surveys of Breeding
Waterfowl in North America. U.S. Department of the Interior, National Biological Service,
Washington, D.C. Biological Science Report 5. 252 p.
"Migratory Bird Hunting and Conservation Stamp (1987-1988 Redhead Ducks)" located at
the web site for the U.S. Department of the Interior, Fish and Wildlife Service, Federal Duck
Stamp Program.
Custer, C.M. 1993. Life History Traits and Habitat Needs of the Redhead. Fish and
Wildlife Leaflet 13.1.11 in the Waterfowl Management Handbook. U. S. Department of the
Interior, Fish and Wildlife Service, Washington, D.C.
Spendelow, J.A., and S.R. Patton. 1988. National Atlas of Coastal Waterbird Colonies in
the Contiguous United States: 1976-82. U.S. Department of the Interior, Fish and Wildlife
Service, National Wetlands Research Center. Biological Report 88(5). 326 p.
Saver, J.R., I.E. Hines, G. Gough, I. Thomas, and E.G. Peterjohn. 1997. The North
American Breeding Bird Survey Results and Analysis. Version 96.4. Pataxent Wildlife
Research Center, Laurel, MD.
"Endangered Species Home Page" located at the web site for the U.S. Dept. of the Interior,
Fish and Wildlife Service
"Gulf Sturgeon" located at the web sites for U.S. Department of the Interior, Fish and
Wildlife Service and the National Marine Fisheries Service.
"Brown Pelican" located at the web sites for U.S. Department of the Interior, Fish and
Wildlife Service
Hawkins, D. 1997. Manatee Populations Rebound. In: People, Land, and Water. Volume 4.
March 1997. U.S. Department of the Interior, Washington, D.C.
VanMeter, V.B. 1989. The West Indian Manatee in Florida. Florida Power & Light Co.,
Miami, FL. 41 p.
62
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O'Shea, T.J., B.B. Ackerman, and H.F. Percival. 1995. Population Biology of the Florida
Manatee. Information and Technology Report 1. U.S. Department of the Interior, National
Biological Service, Washington, D.C. 289 p.
"Kemp's ridley sea turtle" located at the web sites for the Texas Parks and Wildlife
Department, the U.S. Fish and Wildlife Service, and the National Marine Fisheries Service.
Hawkins, D. 1997. Manatee Populations Rebound. In: People, Land, and Water. Volume 4.
March 1997. U.S. Department of the Interior, Washington, D.C.
Public Health
NOAA. 1991. The 1990 National Shellfish Register of Classified Estuarine Waters.
National Oceanic and Atmospheric Administration, National Ocean Service, Rockville, MD.
100 p.
The 1995 National Shellfish Register of Classified Growing Waters" located at the web site
for the National Oceanic and Atmospheric Administration, National Ocean Service, Office of
Ocean Resources Conservation and Assessment.
"1997 Listing of Fish and Wildlife Advisories (LFWA) Database" located at the web site for
the U.S. Environmental Protection Agency, Office of Science and Technology.
"Commercial and Recreational Fisheries" located at the web site for NOAA, National Marine
Fisheries Service, Fisheries Statistics and Economics Division.
U.S. EPA, EMAP-E Database for the Louisianian Province, 1991-1994. U.S. Environmental
Protection Agency, Gulf Ecology Division, Gulf Breeze, FL.
O'Connor, T.P. and B. Beliaeff. 1995. Recent Trends in Coastal Environmental Quality:
Results from the Mussel Watch Project 1986 to 1993. National Oceanic and Atmospheric
Administration, National Ocean Service, Silver Spring, MD. 46 p.
63
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Data Sources
Lowe, J.A., D.R.G. Farrow, A.S. Pait, SJ. Arenstam and E.F. Lavan. 1991. Fish Kills in
Coastal Waters, 1980-1989. National Oceanic and Atmospheric Administration, National
Ocean Service, Office of Ocean Resources Conservation and Assessment, Rockville, MD.
69 p.
"Animal and Plant Mortalities in the U.S." located at the web site for the National Office for
Marine Biotoxins and harmful Algal Blooms, Woods Hole Oceanographic Institution, Woods
Hole, MA.
"The Gulf of Mexico Aquatic Mortality Response Network (GMNET)" located at the web
site for U.S. Environmental Protection Agency, Gulf of Mexico Program.
64
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Appendix I:
National Estuary Programs (NEP) and National Estuarine
Research Reserve Systems (NERRS) in the Gulf of Mexico
The Sarasota Bay NEP
The Sarasota Bay NEP began in 1989 in response to public concern
about pollution and habitat loss from rapid growth, development, and
overuse. Fifty years ago, Sarasota Bay was described as a pristine
estuary with lush seagrass meadows, abundant fish and shellfish, and
clean, clear water. Since then, Sarasota Bay has lost 40% of its
wetlands and suffers from high nutrient loading from nonpoint
sources and toxic contamination of sediments. Through the Sarasota
Bay NEP, a baywide monitoring program was instituted to evaluate
the status of and trends in priority problems such as nitrogen loadings and loss of wetland and
seagrass habitat. In order to improve management of the Bay's resources, the program has
also recommended (1) an alternative development strategy which increases open space and
reduces stormwater runoff and (2) treated wastewater reclamation to be used as an alternative
water source. Sarasota Bay NEP homepage at
http://pelican.ginpo.gov/gulfofinex/estuarypartner/Sarasota/SarasotaBay.htniI
The Tampa Bay NEP
. - -. . Recognizing the need for a comprehensive bay restoration and
protection plan, the Tampa Bay NEP was established in 1991 to
address the harmful effects of growth and development on the water
quality and wetland/seagrass habitats of Tampa Bay. The NEP has
sponsored research into the bay's problems, tested early management
actions, and initiated several public outreach programs to get citizens
involved in protecting the bay. The NEP lists its priority concerns as
water and sediment quality, bay habitats, dredging and dredged
material management, fish and wildlife health, and spill prevention and response. Tampa
Bay has seen marked improvements in water quality and general health over the past several
years, and the goal of the NEP is to ". . . maintain this steady progress, even in the face of
continued growth." Tampa Bay NEP homepage at httjK//aeceงงJ^ilF?i*l"'?' ih ซH
65
-------
Appendix I
The Barataria-Terrebonne NEP
f. H
'
liarataria-Terreboiine
NATIONAl. ESTUARY PROGRAM
Many of the priority issues affecting the health
and stability of the Barataria-Terrebonne basin
relate back to hydrologic modifications,
including levees, dredge canals, and other
artificial structures that change the natural flow of water. In this basin, hydrologic
modifications have led to a reduction in the amount of sediment from the Mississippi River
that settles on the wetlands. The wetlands in this basin are subject to subsidence if the rate of
sediment building falls below the rate of sinking. Habitat loss affects the condition of living
resources and reduces the recreational and commercial value of wetlands and estuaries.
Although habitat loss is the most pressing ecological issue facing the Barataria-Terrebonne
basin, the NEP is also concerned with eutrophication, pathogen contamination, and toxic
contamination. The NEP is currently developing a computer landscape model that will be
used to evaluate the impacts of actions that could be taken to conserve habitat in this
estuarine watershed. Barataria-Terrebonne NEP homepage at
The Galveston Bay NEP
The Galveston Bay NEP was established in 1988 with a mission to
characterize, identify, and assess problems and issues affecting water
quality in Galveston Bay. The major problems affecting the bay are (1)
changes in the amount and timing of freshwater inflow that have
altered salinity patterns in the bay, (2) loss of wetland and seagrass
habitats, and (3) point and nonpoint sources of wastewater that
contribute toxic substances and bacterial contamination to water and
sediments and lead to poor water quality. The greatest challenge
facing the Galveston Bay NEP is finding a balance between competing
human uses and the environment. The NEP has designed a monitoring
program, has implemented management tools to enhance interagency coordination, and has
produced a "State of the Bay" report that characterizes the Galveston Bay ecosystem.
Galveston Bay NEP homepage at
The Corpus Christ! Bay NEP
The Corpus Christi Bay NEP, established in 1992, is a community
based effort to identify the problems facing the bays and estuaries of
the Texas Coastal Bend. The mission of the NEP is (1) to enhance
cooperation among business, government, and the general public to
identify priority problems needing attention, (2) to encourage the use
of appropriate and feasible management actions that will ensure
sustainable utilization of resources in the future, (3) to coordinate
research, planning, management, and public outreach efforts, and (4) to ensure that "everyone
has a voice in managing the Coastal Bend's bays and estuaries." The NEP is currently
66
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Appendix I
investigating several priority issues: altered freshwater inflow, declines in living resources,
loss of wetlands and other habitats, degradation of water quality, altered estuarine circulation,
selected public health issues, and debris. These investigations will identify the status and
trends of water quality and living resources. Corpus Christi Bay NEP homepage at
The Charlotte Harbor NEP
Charlotte Harbor was named to the National Estuary Program in
1995. The NEP was established to address priority problems in
Charlotte Harbor, including hydrologic alterations, water quality
. , degradation, and fish and wildlife habitat loss. As urban development
"^Jl Hfttifl"^ l . . , 1111 r> i i
increases in the watershed, local governments are faced with
balancing conflicting needs for a reliable water supply, treating
residential wastewater, and preserving habitat. The goals of the Charlotte Harbor NEP are to
(1) improve environmental integrity; (2) preserve, restore, and enhance seagrass and
wetlands; (3) reduce point and nonpoint pollution; (4) provide proper freshwater inflow; and
(5) develop and implement a strategy for public participation and education as well as a
formal management plan to achieve these goals. Charlotte Harbor NEP homepage at
The Mobile Bay NEP
Mobile Bay was designated as a NEP in 1995. Mobile Bay NEP is
currently working towards prioritizing the environmental problems of
Mobile Bay by holding monthly workshops that involve the public and
the Technical and Citizens Advisory Committees. These workshops
allow everyone to voice their concerns about the bay and to come to
consensus on priority issues. Concurrently, a scientific literature
review will compile and analyze the existing data for Mobile Bay
water quality, living resources, and human uses. Mobile Bay NEP
homepage at: :..^./<;i..;....;..;..:.;.;,,, :./.'../ :..1,;.Y...^..:...;.:.:..:..:.!....L' '...'...I
Weeks Bay NERRS
Weeks Bay is a small, shallow, estuarine embayment off Mobile Bay, fringed with marsh and
forested wetland. Designated an Outstanding National Water Resource in 1992, the Weeks
Bay watershed is ideally sized for estuarine research projects. Research from before 1990
focused primarily on obtaining baseline data, including projects on SAV type and abundance,
nursery habitats and indicator species since little was known about the relatively pristine and
unimpacted rural bay. Post-1990 research has included estuarine modeling, studies of salinity
regime, non-point source pollution and land-use studies, nutrient production and input,
community and habitat studies, migratory bird banding, and pesticide impacts. Current
67
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Appendix I
research efforts at the Weeks Bay NERR and within its watershed include hydrodynamic
modeling, floral and faunal inventories and ongoing assessment and abatement of nonpoint
pollution.
Apalachicola Bay NERRS
The Apalachicola Bay is the largest of the currently existing NERR sites, with 193,758 acres
of land and water within its boundaries, and potential for considerable expansion. The overall
high water quality of the Apalachicola estuary, combined with other factors, provides ideal
living conditions for estuarine biota, resulting in a highly productive estuarine system. The
myriad of habitats found within the reserve support a wide range of plant and animal species,
many of which are threatened or endangered. Research activities of the reserve include
long-term monitoring of physical, chemical, and biological parameters important to estuarine
productivity; a marsh restoration/breakwater demonstration program; on-site assistance for
regional research projects; and protection and monitoring programs for threatened sea turtles
and migratory bird nests. An onsite, computerized library consisting of over 3,700
publications is available for use by visiting researchers. From 1990 to 1995, over 40 research
and monitoring projects were undertaken by staff and outside investigators.
Rookery Bay NERRS
The Rookery Bay NERR is located at the northern end of the Ten Thousand Islands on the
gulf coast of Florida, one of the largest mangrove-forested regions in the U.S. Rookery Bay
represents one of the few remaining undisturbed mangrove estuaries in North America.
Pristine mangrove forests surround shallow bay waters and the upland buffer consists of pine
flatwoods and dry-zone scrub. Visiting scientists utilize on-site laboratory facilities for
systems and baseline studies of the plant and animal communities of the reserve. Research
conducted at the site has included the study of nutrient cycling in mangrove systems,
estuarine food webs, estuarine faunal abundance, and bird population dynamics. Long-term
ecological monitoring efforts of the Rookery Bay NERR include water quality monitoring
(physical, chemical, and biological), meteorological and tidal conditions, and benthic
invertebrates. Data generated from the research programs are used to assess the health of the
Rookery Bay ecosystem, guide future research efforts, and develop new management policies
and educational programs for the reserve.
68
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Appendix II:
Characteristics of Estuaries in the Gulf of Mexico
Definitions
Low Water Clarity = < 10% Transmission of ambient light to 1 m depth
High TON = Total dissolved nitrogen >= 1 mg/L
High Chlorophyll = Chlorophyll a > 20 ug/L
Hypoxia = at least 1 event of DO >0, <= 2 mg/L
Anoxia = at least 1 event of DO =0 mg/L
Low DO = Minimum bottom dissolved oxygen cone, over 12 hours is < 2 mg/L
High Sediment Contaminants = more than 5 analytes had concentrations > ER-L (Long et al. 1995)
Coastal Wetlands includes Salt/Fresh Marsh, Forested Scrub/Shrub, Tidal Flats
SAV = Submerged Aquatic Vegetation
Degraded Benthos = Benthic index < criteria for a province
% Fish with Pathology = Number offish with observed pathology / number offish sampled
Harvest Limited Shellfish Beds include beds conditionally approved, restricted, & prohibited for harvest
69
-------
Appendix II
Estuary
Florida Bay
Ten Thousand Islands
Charlotte Harbor
Sarasota Bay
Tampa Bay
St. Josephs Bay
Waccasassa Bay
Suwannee Sound
Apalachee Bay
Apalachicola Bay
St. Andrew Bay
Choctawhatchee Bay
Pensacola Bay
Perdido Bay
Mobile Bay
Mississippi Sound
Lake Borgne
Lake Pontchartrain
Breton/Chandeleur Sounds
Mississippi River
Barataria Bay
Terrebonne/Timbalier Bays
Atchafalaya/Vermilion Bays
Calcasieu Lake
Sabine Lake
Galveston Bay
Brazos River
Matagorda Bay
San Antonio Bay
Aransas Bay
Corpus Christ! Bay
Laauna Madre
ro
(D
,
ฑi
^C
15
tt>
1
31
17
13
30
27
66
26
16
30
22
31
25
23
15
19
24
7
2
27
6
13
18
1
12
11
11
28
19
13
15
22
36
(M
>,
(0
O
i
OT
#
1
37
42
9
2
11
40
22
58
17
32
7
61
43
78
72
60
75
74
46
77
67
62
83
63
48
61
96
68
71
87
73
32
% Area with
Low Water Clarity 2
0
50
67
0
0
0
0
96
16
12
0
<1
<1
8
<1
5
9
13
9
36
23
3
59
99
6
39
0
32
72
0
34
0
li
-------
Appendix II
Estuary
Florida Bay
Ten Thousand Islands
Charlotte Harbor
Sarasota Bay
Tampa Bay
Waccasassa Bay
Suwannee Sound
Apalachee Bay
Apalachicola Bay
St. Josephs Bay
St. Andrew Bay
Choctawhatchee Bay
Pensacola Bay
Perdido Bay
Mobile Bay
Mississippi Sound
Lake Borgne
Lake Pontchartrain
Breton/Chandeleur Sounds
Mississippi River
Barataria Bay
Terrebonne/Timbalier Bays
Atchafalaya/Vermilion Bays
Calcasieu Lake
Sabine Lake
Galveston Bay
Brazos River
Matagorda Bay
San Antonio Bay
Aransas Bay
Corpus Christ! Bay
Laauna Madre
_c
^
If
Jl
100
58
48
25
14
0
3
14
13
54
16
48
46
19
0
25
13
0
22
0
5
50
10
21
47
25
20
0
23
17
"ro
'x
o
<
.c
ฑi
ro
(D
<
ฃ
15
46
42
25
10
0
<1
0
13
23
0
1
8
<1
0
9
5
0
14
0
3
10
0
<1
0
0
0
0
0
7
1
-C
ฑi
ro
260
5
53
99
30
91
8
32
9
13
3
8
0
5
30
80
8 14
80
0
0
18
7
16
21
13
191
% Area with
Degraded Benthos2
12
50
89
50
58
0
4
0
5
100
0
58
25
100
19
18
0
13
5
76
0
16
54
0
44
45
100
22
80
98
21
24
% Fish with
Pathology2
0
0
0
0
0
0
3.25
0
0
0.03
<0.01
0.01
0.01
0.01
0.01
0.05
0.02
0.04
0
0.58
0.06
0.03
0.09
0.01
0
0
0
% Acres of Harvest
Limited Shellfish
Beds5
7
50
100
69
52
100
71
100
100
100
100 6
100
63
176
100 6
18
92
41
13
100
100
100
61
100
23
35
24
26
79
Sources of Data:
6 NOAA (1990) National Shellfish Register
7 NOAA (1990) Estuaries of the United States
8 National Biological Service (1995) Our Living Resources
9 Personal Communication K. Gustafrom, Sarasota NEP
71
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-------
The Ecological Condition of Estuaries in the Gulf of Mexico is a joint
publication by U.S. EPA's Gulf Ecology Division and USGS/NWRC's Gulf
Breeze Project Office (EPA 620-R-98-004, July 1999). As another means of
distribution, we have created a CDROM product which provides 2
versions of the document in Adobe Systems Incorporated's portable
document format (PDF) - the first is a "low-resolution" version suitable for
viewing purposes; the second is a "high-resolution" version suitable for
high quality printing purposes.
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