United States
      Environmental Protection
      Agency
Science and Ecosystem
Support Division
Region 4 and
Office of Research &
Development
EPA-904-R-96-008
December 1996
South Florida Ecosystem Assessment
               Interim Report
                         \ AGRICULTURAL
                                     h-LOXAHATCH6E
                                      NATIONAL-
                                     WILDLIFE REFUGE
         -
-Wsf
                     Altigator 1 /  WA
                     Alley NCONSERV.
                         V  AREAS^
                     IBIG CYPRESS
                     I NATIONAL
                      PRESERVE
                          WCA-3A,
                       EVERGLADES
                       NATIONAL

Monitoring for
  plications'
  ptive Management:
   '* stem Restoration
                                  t-vt
                                  •

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                                        EPA 904-R-96-008
                                         December 1996
          SOUTH  FLORIDA
 ECOSYSTEM ASSESSMENT
 MONITORING FOR ADAPTIVE MANAGEMENT:
IMPLICATIONS FOR ECOSYSTEM RESTORATION
                (Interim Report)
                       by
              Jerry Stober, Project Manager
        U.S. Environmental Protection Agency Region 4
          Science and Ecosystem Support Division
                    Athens, GA

          Daniel Scheldt, Assistant Project Manager
        U.S. Environmental Protection Agency Region 4
               Water Management Division
                    Atlanta, GA

                    Ron Jones
              Florida International University
         Southeast Environmental Research Program
                     Miami,  FL

                   Kent Thornton
                 FTN Associates, Ltd.
                   Little Rock, AR

                  Robert Ambrose
           U.S. Environmental Protection Agency
  National Health and Environmental Exposure Research Laboratory
                    Athens, GA

                   Danny France
        U.S. Environmental Protection Agency Region 4
          Science and Ecosystem Support Division
                    Athens, GA

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The South Florida Ecosystem Assessment is being accomplished through the cooperation of federal and
state natural resource agency specialists. The agencies include the US Environmental Protection Agency,
the US Fish and Wildlife Service, the US Geological Survey, the US National Park Service, the Florida
Department of Environmental Protection, the South Florida Water Management District, and the Florida
Game and Freshwater Fish Commission. Florida International University Southeast Environmental Research
Program is also a partner in this effort.
                                            JB
                                     FLORIM
        u&
    riSH iU'iUJI.LI E
       SKKVJOK
                              Program

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South Florida Ecosystem Assessment Report
           % OM = percent organic matter
           CM = centimeter
           FT = foot
           KM = kilometer
           kg/yr = kilogram per year
           ppb = parts per billion (ug/L)
           ppt = parts per trillion (ng/L)
           ng/L = nanogram per liter (ppt)
           mg/L = milligram per liter (ppm)
           ug/kg = parts per billion (ppb)
           uMol/hr = micromoles per hour

           Hg  = mercury
           Hg° = elemental mercury
           Hgll = inorganic mercury
           MeHg = methylmercury

           APTMD = Air, Pesticides, and Toxics Management Division
           EAA = Everglades Agricultural Area
           EMAP = Environmental Monitoring and Assessment Program
           FID SERP = Florida International University Southeastern
              Environmental Research Program
           NHEERL-ATHENS = National Health and Environmental Exposure
              Research Laboratory - Athens, GA
           NHEERL - RTP = National Health and Environmental Exposure
              Research Laboratory - Research Triangle Park, NC
           NPS = National Park Service
           ORC = Office of Regional Counsel
           REMAP = Regional Environmental Monitoring and Assessment Program
           SESD = Science and Ecosystem Support Division
           SFWMD = South Florida Water Management District
           US EPA = United States Environmental Protection Agency
           USGS = United States Geological Survey
           WCA = Water Conservation Area

           BASS = Bioaccumulation and Aquatic System Simulator Model
           MERCS = Mercury Cycling Model, Version 5

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                                          South Florida Ecosystem Assessment Report
                                     EXECUTIVE  SUMMARY
   The purpose of this interim report is to introduce the systemwide
(4000-square-mile) scope of the monitoring project in the Everglades
ecosystem and  to present preliminary findings  on the mercury
contamination, eutrophication,  habitat  alteration, and hydropattern
modification issues. The greatest threat to the Everglades ecosystem is to
assume these issues are independent. The monitoring in this project
strongly supports the federal and state Everglades restoration efforts and
will provide a means to evaluate present and future management actions.
This project is focused on the ecological risk assessment  process and
guided by a set of policy relevant questions. A statistical survey design was
used to select 200  canal  and 500 marsh  sampling stations,  a quarter of
which were sampled during successive wet and dry  seasons over two
years. These data allow quantitative estimation of the  relative risk to the
ecological resources  from multiple environmenta threats.  Marsh
monitoring has been conducted during two years, one of which was the
wettest year on record. To determine the range of natural variance to
support and validate mercury modeling, process studies, and future
assessments, this  monitoring should continue.
   The highest mercury  concentrations in  algae, fish, and  great egrets
have been found to occur in Water Conservation Area 3 between Alligator
Alley and Tamiami Trail.  No single point source has been identified that
contributes directly  to these high mercury levels. Atmospheric mercury
loading from precipitation is from 35 to 70 times greater in the publicly
owned Everglades than mercury loading in canal water coming from the
Everglades Agricultural Area. Incineration  in the urban areas is likely the
primary source of atmospheric mercury.
   Several  policy and  management implications arose  from these
preliminary results including:  (I) the current chronic mercury aquatic life
criterion  is  underprotective and needs to be revised; (2) discharging
phosphorus at the current initial control target of 50 ppb will continue to
allow eutrophication of over 95% of the Everglades marshes;  and (3)
ecological restoration must consider hydropattern modification,  nutrient
loading, mercury cycling, and  habitat alteration simultaneously, not
independently.
    Comparative ecological risk assessment is a critical element in adaptive
management for ecosystem restoration. This ecosystem assessment
project provides a critical framework and foundation for assessing the
effectiveness of Everglades ecosystem restoration activities into the 21st
century.

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                           South Florida Ecosystem Assessment Report
Contents
US EPA REGION 4

SOUTH FLORIDA
ECOSYSTEM
ASSESSMENT
INTRODUCTION 	 1
 SOUTH FLORIDA EVERGLADES	 1
 ISSUES	3
 US EPA REGION 4 ECOSYSTEM
  ASSESSMENT PROJECT..	,. 7
HIGHLIGHTS	11
 EUTROPHICATION	11
 MERCURY CONTAMINATION	 13
 HABITAT ALTERATION	 17
 HYDROPATTERN MODIFICATION	 18
ECOSYSTEM RESTORATION
TOOLS................................................. 19
POLICY AND MANAGEMENT
IMPLICATIONS	21
 WATER QUALITY	 21
 AIRQUALITY	23
 ASSESSING THE RISK	 23
ON-GOING AND FUTURE STUDIES.. 25

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              South Florida Ecosystem Assessment Report
ACKNOWLEDGEMENTS
                        PARTICIPANTS IN US EPA REGION 4
                        EVERGLADES ASSESSMENT PROJECT
                        US EPA Region 4
                        Program Offices

                        APTMD
                        L. Anderson-Carnahan
                        D. Dubose
                        L. Page
                        ORC
                        P Mancusi-Ungaro
                        SESD
                        B. Berrang
                        P Meyer
                        C. Hal brook
                        M. Parsons
                        D. Smith
                        W McDaniel
                        M.Wasko
                        J. Scifres
                        M. Birch
                        PMann
                        T. Slagle
                        T. Stiber
                        J. Davee
                        D. Colquitt
                        D. Kamens
                        R. Howes
                        G. Collins
                        J. Bricker
                        B. Noakes
US EPA - Office of Research
and Development

EMAP
R. Linthurst
K. Summers
T. Olsen
NERL-RTP
R. Stevens
R. Bullock
J. Pinto
NERL-ATHENS
R. Araujo
C.  Barber
N.Loux
L. Burns

FIU-SERP
RJaffe
J. Trexler
Y.Cai
A. All
N. Black
I.MacFarlane
W. Loftus
I.Thomas
University of Georgia
S. Rathbun
Florida Department of
Environmental Protection
T. Atkeson
South Florida Water
Management District
L. Fink

Contractors
J.Maudsley, Mantech
B. Lewis, Mantech
M.Weirich, Mantech
D. Stevens, Mantech
M. McDowell, Mantech
C. Laurin, FTN Associates, Ltd.
J. Benton, FTN Associates, Ltd.
R. Remington, FTN Associates, Ltd.
S. Ponder; Integrated Laboratory
 Systems
K. Simmons, Integrated Laboratory
 Systems
S. Pilcher, Integrated Laboratory
 Systems
E. Crecelius, Battelle Marine Sciences
B. Lasorsa, Battelle Marine Sciences
                        PHOTO CREDITS
                        US EPA Region 4 provided the cover photo. The USGS provided Figure I. D. Scheldt of the US EPA contributed
                        Figures 2, 3, 5,  6, 7, 12, 35, and 39. R Meyer of the US EPA contributed to Figures 2 and 33. The US NPS
                        contributed Figure4.J. StoberoftheUSEPAprovided Figures I I and37.T. Cawleyprovided Figure 13. PFredricks
                        of the University of Florida provided the great egret data presented in Figure 26. The SFWMD provided Figure 36.

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                                         South Florida Ecosystem Assessment Report
                                                    INTRODUCTION
SOUTH FLORIDA EVERGLADES
   "There are no other Everglades in the world.
They have always been one of the unique regions
of the earth. Nothing anywhere else is like them:
Their vast glittering openness, wider than the
enormous visible round of the horizon, the racing
free saltiness  and  sweetness  of their massive
winds, under the dazzling blue heights of space1."

   The Florida Everglades  is one of the largest
freshwater marshes  in the world. Just one
hundred years ago  this vast  wilderness
encompassed over 4000 square miles, extending
 00 miles from the shores of Lake Okeechobee
south to the coast.  Subtle irregularities in ground
elevation resulted in a mosaic of sawgrass marsh,
wet prairies,  sloughs, and tree islands. The
intermingling of temperate and Caribbean flora
created habitat for a variety of fauna, including
the Florida panther,  the alligator, and the hundreds
of thousands  of wading birds with which the
Everglades were synonymous. The unique and
timeless characteristics  of the  Everglades were
described by Marjory Stoneman Douglas in her
classic work, The  Everglades:  River of Grass. This work brought the
Everglades to national and international  attention as a natural resource
worthy of preservation.
Figure 1. USGS satellite image of South Florida: light
areas on the east indicate urban areas; dark areas in
the center are the remnant Everglades; and the red
area at the top is the EAA.
                   "They were changeless. They were  changed1
   During the last century, the Everglades ecosystem has been altered to
provide for extensive agricultural and urban development (Figure  ). Today,
50% of the  historic  Everglades wetlands  have been drained, and an
   1Marjory Stoneman Douglas. 1947. The Everglades: River of Grass. Banyan Books.
   Sarasota, FL.

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  South Florida Ecosystem Assessment Report
                  Everglades Ecosystem
                                                     LOXAHATCHEE
                                                      NATIONAL
                                                    WILDLIFE REFUGE
   Wet Prairie •
Floating Periphyton
                                                          Wot Prairie -
                                                         Sawgrass Marsh
  Cypress Forest
                     Figure 2, Everglades ecosystem commuriilies

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                                            South Florida Ecosystem Assessment Report
expanding South Florida human population of nearly 6  million competes
for this ecosystem's water and land.

   The Everglades changed dramatically as drainage canals were dug and
agricultural  and urban development increased in the 20th century.  Most
of the remaining Everglades are in Loxahatchee  National Wildlife Refuge,
Everglades National Park, orthe Water Conservation Areas (WCAs) (Figure
2). Today, Everglades National  Park includes only one-fifth of the original
river of grass that once spread over more than 2 million  acres. One-
fourth of the historic Everglades is now in extensive agricultural production
within the  1000-square-mile Everglades Agricultural Area (EAA), where
sugar cane  and vegetables are grown  on fertile peat soils.  Big Cypress
National Preserve protects forested swamp resources within the Everglades
watershed.  Although half of the 16,000-square-mile Everglades watershed
is  in  public  ownership, there are a number of environmental  issues that
must be resolved to restore  and protect the  Everglades ecosystem,
including eutrophication; mercury contamination of gamefish, wading birds,
and  other  top predators; habitat alteration  and loss; hydropattern
modification; water supply  conflicts; endangered species;  and nuisance
exotic species introductions.

ISSUES
   Eutrophication
   Nutrient loading from the Everglades Agricultural Area
and  urban  areas has significantly increased nutrient
concentrations, particularly phosphorus, in the downstream
Water Conservation Areas and the Park, resulting in major
eutrophic impacts to these wetland systems (Figure 3).
Among the progressive Everglades eutrophic impacts are
increased  soil phosphorus  content,  changed natural
periphyton communities,  increased oxygen-demanding
organic  matter, loss of water dissolved oxygen, loss of native sawgrass
plant communities,  loss  of important wading bird foraging habitat, and
conversion  of wet prairie plant communities to cattails. These collective
changes are systemic and impact the structure and function of the aquatic
Figure 3. Eutrophication promotes cattail
expansion.

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              South Florida Ecosystem Assessment Report
Figure 4. Florida panther, an endangered
species, died from mercury toxicity.
Figure 5. Wading birds have
elevated mercury levels.
              system. The  Florida  Department of Environmental
              Protection (FDEP) has concluded that eutrophication of the
              Everglades results in the violation of four Florida water
              quality standards to protect fish and wildlife and creates an
              imbalance in  natural populations of aquatic flora and fauna,
              with a resulting loss in biological  integrity. Some eutrophic
              impacts, such as periphyton community changes, are
              thought to be short-term and reversible if nutrient additions
can be significantly decreased. Other  impacts are considered  long-term
(decades), such as loading peat soil with excess phosphorus that triggers
the loss of native plant communities and foraging habitat.  The  nutrient
levels required to sustain the natural  balance of oligotrophic plants and
animals into future decades and centuries are currently under  debate.
There are still many marsh areas where natural  water phosphorus
concentrations are less than  0 ppb. A combination of agricultural  best
management practices and construction of over 40,000 acres of wetlands
(Stormwater Treatment Areas) are being implemented in an attempt to
control phosphorus loadings. The effectiveness ofthese controls in reducing
nutrient concentrations to near historic levels, however, is not yet known.
      Mercury Contamination
         Many of South Florida's fresh waters are under human health
      fish consumption  advisories because of mercury contamination in
      largemouth bass  and  other top  predator fish.  Mercury
      concentrations in an endangered Florida panther were high enough
      to either have killed or contributed to the death of that panther in
       1989 (Figure 4). Wading bird populations today are about one-fifth
      of their abundance  in  the   930s.  Wading  bird  mercury
      concentrations also are high  in certain Everglades areas, one of
      many factors that  might be contributing to their decline (Figure 5).
      The  sources and factors contributing to this mercury contamination
      and bioaccumulation are not yet clearly understood. If the sources
      or critical processes can be identified,  understood,  and  managed,
      the effects of mercury contamination may be reversible. This
      reversal, however, could take decades to realize even with effective
      management practices.

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South Florida Ecosystem Assessment Report
    Figure 6. Urban development has altered water
    flow and habitat.
   Habitat Alteration and Loss
   Over   million acres  of the original River of
Grass have been drained and altered for other uses
since  the turn of  the 20th century (Figure 6). In
addition to the habitat lost, much of the  remaining
habitat  has been altered because  of  unnatural
flooding and drying, ground  water removal, or
similar  perturbations.  This  habitat alteration  is still  ongoing as the
population of South Florida continues to expand.  Unlike eutrophication
and mercury contamination,  habitat loss is irreversible with certain land
uses.  In addition, habitat alteration aggravates other environmental
problems, and these interactions are poorly understood.

   Hydropattern Modification
   Clearly, the greatest change that has occurred
in the Everglades ecosystem is due to changing the
hydropattern, orthe depth, timing, and distribution
of surface water,  that occurred  naturally  in these
systems (Figure 7). Wetland systems, by definition,
are driven  by water. Canal  drainage systems, levees,
flood control  structures,   and  water supply
 ,     •    ,        I,  ,.        , -,  ,   • •  i
diversions have  collectively contributed to large-
scale changes that have occurred in the Everglades
ecosystem. The US Army  Corps of Engineers in their Central and Southern
Florida Project Re-Study is evaluating the modification of canals and levees
to return the hydropattern to a more  natural regime.  Determining the
natural flow regime and hydropattern and subsequently implementing the
required flows in  the Everglades is a major restoration activity. "Draining
the swamp" represents one  of the greatest issues facing the Everglades
ecosystem.

   Endangered and  Exotic Species
   The  South Florida ecosystem is known for its great diversity of  plants
and animals, many  of which are  endangered. Florida  also has a large
number of introduced or nonnative fish and  birds, which compete with
    Figure 7. Extensive canal systems and water
    maunagement have modified tneynatural nydropat.
    tern.

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     South Florida Ecosystem Assessment Report
                the native species. These introduced or exotic species are not restricted
                to fauna; there are also significant numbers of nonnative  plants.  The
                melaleucatree, for example, has taken over large areas of the Everglades.
                This species was originally introduced  because of its ability  to transpire
                water and help drain the wetland areas.  Eliminating  introduced species
                altogether is unlikely, but practices for  minimizing their impact on native
                habitat and  preventing  continued  expansion into the Everglades are
                needed.

                   Interaction Among  Issues
                   None of the issues discussed  above are  independent of the others.
                These issues are all intertwined, each problem affecting other problems.
                Addressing these issues requires a large-scale perspective. Integrated and
                holistic studies of the multiple  issues  impacting the  Everglades need to
                compare the risks  associated with all impacts and their interactions.  The
                US EPA South  Florida Ecosystem  Assessment effort is a project  that
                provides a foundation for addressing these issues and contributes to the
                InterAgency Task Force on Ecosystem Restoration efforts.

The  greatest  threat to  the Everglades  ecosystem  is to  assume
the  issues are independent.

                   Ecosystem Restoration
                   Among the federal and state Everglades restoration efforts in progress
                are the EAA phosphorus control program and projects to restore water
                delivery (and ecology) throughout the  Everglades. The present US  EPA
                South Florida Ecosystem Assessment effort integrates several  important
                restoration  issues  and provides a critical science-based foundation for
                ecosystem assessment and restoration. Long-term monitoring will provide
                critical  baseline information to evaluate  ecosystem restoration.  More
                importantly, continued  monitoring is the  only  way to evaluate the
                effectiveness of management strategies to improve ecological conditions.

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                                          South Florida Ecosystem Assessment Report
US EPA REGION 4 SOUTH FLORIDA ECOSYSTEM
ASSESSMENT PROJECT
   The   US  EPA  Region  4  Regional
Environmental Monitoring and Assessment
Program  (REMAP) is an innovative, long-
term research, monitoring and assessment
program designed to measure the current
and  changing condition of ecological
resources in South Florida. The ultimate
goal of this program is to provide decision
makers  with sound ecological data to
improve environmental management
decisions on multiple environmenta issues
and restoration efforts. The Region 4 South
Florida Ecosystem Assessment Project uses
the US  EPA ecological risk assessment
framework  as a foundation for providing
decision  makers with critical  information
(Figure 8). The program is guided by seven
policy-relevant questions:
        Ecological Risk Assessment
             PROBLEM FORMULATION
                Characterization of

             Exposure -4—*• Ecological
                            Effects

•^
RISK

•^"
C


^" ^
HARACTERi;

•^s
7.fl

w
JION
Figure 8. Ecological Risk Assessment Framework. Ecological
risk assessment is a way of determining the likelihood of
adverse ecological effects from a pollutant or management
practice.
     Magnitude - What is the magnitude of the mercury problem?
     Extent - What is the extent of the mercury problem?
     Trend - Is the problem getting better, worse, or staying the
     same?
     Cause - What factors are associated with or causing the
     problem?
     Source - What are the contributions and importance of
     mercury from different sources?
     Risk - What are the risks to different ecological systems and
     species from mercury contamination?
     Solutions  - What  management alternatives are available to
     ameliorate or eliminate the mercury contamination problem?

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           South Florida Ecosystem Assessment Report
*Probability Samples:
Foundation For Regional
Risk Assessment
   Probability samples are  samples
where every member of the statistical
population has a known chance of being
selected and where the samples are drawn
at random. The project used a statistical
survey design in selecting its probability
samples so that the samples were drawn
in direct proportion to their occurrence in
the population; whether it was EAAor
WCA canals, sawgrass or cattail marshes,
or soil type. The measurements taken
can be used to estimate the proportion
(extent) and condition of that resource in
South Florida. The probability of selecting
the site is known and the site represents
that resource in an unbiased manner The
sampling design is not biased to favor one
marshtype overanother(e.g., sampling
only the marshes next to a road because
it was easier, or selecting a canal because
it looked good or bad). The riskto any of
the ecological resources from the multiple
environmental threats in South Florida is
a direct  function of the extent and
magnitude of both the threat and the
ecological effects. Without probability
samples, these risks can not be realistically
estimated. Probability samples provide the
foundation for ecological risk assessment
in South Florida.
   The seven questions listed are equally
applicable to each issue  impacting the
Everglades ecosystem, such as  mercury
contamination,  eutrophication, habitat
alteration, or hydropattern modification.

   The Region 4 project used a random,
probability-based sampling strategy to
select sites for sampling *.  Samples were
collected   from   south   of  Lake
Okeechobee to the mangrove fringe on
Florida Bay and from the ridge along the
eastern coast into Big  Cypress  National
Preserve on the west. The distribution
of 200 canal samples is shown  in Figure
9 while the distribution of 500  marsh
samples  is shown in  Figure  10. The
samples represent the current ecological
condition in over 750 miles  of  canals
and in over 3000 square miles of marsh
(over 2  million acres). The canals were
sampled  in September  993,  May  and
September  1994, and  May 1995. The
marshes were sampled  in April and
September    995   and  May  and
September  1996. This corresponds to
two  dry  (April and May)  and  two wet
(September) seasons for  both systems
over a two-year period.  The project
sampling included water (Figure   I),
canal sediment, marsh soil (Figure   2),
fish (Figure   3), and agae at each canal
and marsh sampling site location  during
each sampling period. The parameters
                                                                           -K     ,   -v   •(
                                                                              "jWjb^T^
      •
        v*%-~}-
                "S
"-^-r
Figure 9. 200 sampling sites are
located on over 750 canal miles.
                                                                            Figure 10. 500 sampling sites are
                                                                            located on over 2 million marsh acres.

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                                             South Florida Ecosystem Assessment Report
that were measured at each site can be used to answer
questions on multiple issues, including
    Eutrophication (e.g., Total phosphorus,
       cattail,  sawgrass,  and  periphyton
       distribution)
    Mercury  contamination (e.g.,  mercury in
       water, soil, agae, and mosquitofish)
    Habitat alteration (e.g., plant community
       distributions throughout South  Florida)
    Hydropattern modification (e.g., water
       depth at all sites)
Figure 11. Helicopters and air boats were
used for sampling the marsh.
   In addition to the canal and  marsh  sampling,  four
transects established from the edge of a canal into the marsh
along eutrophic gradients and the mercury load from seven
canal structures were also sampled.

   The study is providing information  critical to the South
Florida  Ecosystem Restoration Task Force.  The project  is
providing  information to answer the  policy-relevant
questions raised above and to determine if the precursor
and ecological success criteria identified by the Task Force
are being achieved.

   This study permits a synoptic  look at the  ecological
condition of the entire freshwater canal and marsh system
in South Florida  from Lake Okeechobee to the Florida
mangrove systems. This large-scale perspective is needed
to understand the impacts of different factors, such as
phosphorus,  mercury,  habitat  alteration, or hydropattern
modification, on the entire system rather than a small piece
or area.  Looking  only at isolated pieces in any given  area
and extrapolating to South Florida would provide a distorted
perspective. The statistical sampling approach permits
Figure 12. Soil cores were collected at each
of the marsh sites and analyzed for mercury,
nutrients, and other constituents.
Figure 13. Mosquitofish were sampled
because they are common in both the canals and
the marsh.

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              South Florida Ecosystem Assessment Report
8! 26.20
Q
3
     APRIL & SEPTEMBER 1395
       COMBINED SEASONS

            KA-
APRIL & SEPTEMBER 1995/^V,
  COMBINED SEASONS 'k. '.\

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      $yJi'~d-    '''• ^Vj-J

                               ml*-
                                ^Mf.
                                                   M.CO

                                                   20.00

                                                   10.09

                                                   D.ra
                                 -31 00  -80.80  -80.60   -80.40
       -81.00  -80.80  -8060   -80.40
                        LONGITUDE, degrees
Figure 14. Thickness of the soil       Figure 15. Percent Organic
or peat deposits throughout the         Matter in top soil throughout the
marsh.                           marsh.
quantitative estimates, with known
confidence,  about population
characteristics, such as acres of
marsh  in cattails, percent of the
marsh  with fish mercury con-
centrations  greater  than the
proposed predator protection
level of  00 ppb (see  page  4),
or percent of the canal  miles with
tota  phosphorus concentrations
greater than the Phase I control
target  level  of 50  ppb. Study
information  is  aiding  decision
makers with its significant findings
related to the major issues facing
ecosystem  restoration  in South
Florida.
                            In addition to providing answers to policy relevant questions, the
                         project also  is  contributing to a better scientific understanding of the
                         Everglades ecosystem. A holistic picture of soil thickness (Figure  14) or
                         percent organic matter (Figure 15) is not only scientifically important but
                         also provides insight into areas with peat subsidence and areas of organic
                         soils that might bind phosphorus or metals.

                            This  study, while  contributing  to  the  development of adaptive
                         management practices, also provides the information needed to evaluate
                         the effectiveness of these management practices. For example, once the
                         Phase I phosphorus control program is in  place, phosphorus concentrations
                         throughout the canal and marsh system can be reassessed to evaluate the
                         effectiveness of the control program.
                            The following is a summary of  993-95 study highlights based on all
                         four canal sampling events (two wet and two dry seasons) and the first
                         two marsh sampling events (one wet and one dry season).
10

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                                                           South Florida Ecosystem Assessment Report
                 Total P >50 ppb (44%)
                                                                           HIGHLIGHTS
                                                  EUTROPHICATION
Total P 25-50 ppb
(20%)
                  Total P 10-25 ppb (25%)

Figure 16. South Florida canal water total phosphorus
concentrations distributions during the wet season.
                                    Historically, the  Everglades
                                 ecosystem was nutrient poor, with
                    Total P<10 ppb phosphorus concentrations less
                            (11%) K
                                 than  10  ppb over large areas.
                                 Increased total phosphorus  con-
                                 centrations and  eutrophication
                                 have  been   associated   with
                                 discharges from  the  Everglades
                                 Agricultural Area into the Water
Conservation Areas, particularly the Refuge and Water Conservation Area
2A. In  995 about 45% of the canal miles (about 340 miles) in both the
wet and dry seasons had total  phosphorus concentrations greater than
the Phase I control target of 50  ppb (Figures 16 and  7). In contrast only
2% (wet season) to 5% (dry season) of the marsh area (about 39,000 to
80,000 acres) had tota phosphorus concentrations in excess of 50 ppb
(Figures  I 8 and 19). It is clear the canals are delivering tota  phosphorus
to the marsh.
                    Discharging phosphorus at the Phase I
                 control target of 50 ppb will continue to result
                 in  eutrophication of over  95% of the
                 Everglades marshes. During the wet season,
                 88% of  the marsh (over  1.6  million acres)
                 has a total phosphorus concentration of less
                 than 25 ppb, or half this target concentration,
                 and over 35% of the  marsh has a total
                 phosphorus concentration less than 10 ppb
                 during the wet season.
                                              Total P >50 ppb (46%)
                                         Total P 25-50 ppb
                                         (34%)
                                                                         Total P<10 ppb
                                                                                  (2%)
                                                                   Total P 10-25 ppb (18%)
                                                          Figure 17. South Florida canal water total phosphorus
                                                          concentrations distributions during the dry season.
                     Discharging phosphorus at the Phase I control target of 50 ppb will continue
                     to  result in eutrophication of over 95% of the Everglades marshes.
                                                                                                      11

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               South Florida Ecosystem Assessment Report
Total P 10-25
(51%)
ppb
                                   Total P 25-50 ppb
                                               (10%)
                                      Total P >50 ppb
                                                 (2%)   <35%>
                Total P<10 ppb (37%)
 Figure 18. South Florida marsh water (area-weighted) total
 phosphorus concentrations distributions during the wet season.
                                                        Total P 1 0'25
                                    Total P 25-50 ppb
                                                 (35%)
                                                                                     Total P >50 ppb
                                                                                                 (5%)
                                                             Total P<10 ppb (25%)

                                            Figure 19. South Florida marsh water (area-weighted) total
                                            phosphorus concentrations distributions  during the dry season.
                              Average total phosphorus
                           canals north of Alligator Alley
                              Canals
                  Seasonal Average Total Phosphorus, ppb
        North of
   Alligator Alley
 Alligator Alleyto
   Tamiami Trail
        South of
    Tamiami Trail
                                         Wet
                                     | Dry
Figure 20. Water total phosphorus distribution in canals from
north to south. Note:  50 ppb is the Phase I control target.

                             Marsh
                 Seasonal Average Total Phosphorus, ppb
        North of
   Alligator Alley
 Alligator Alley to
   Tamiami Trail
        South of
   Tamiami Trail

                             Wet
                                                   Dry
concentrations  in the canals are highest in
near and within the EAA (Figure 20). The
    average total  phosphorus concen-
    trations in  the  canals above Alligator
    Alley are about 4 times higher than in
    the marshes above Alligator Alley during
    the wet season (Figures 20 and 2 ).
    While  the  average total  phosphorus
    concentrations are similar in the canals
    and marshes south  of Tamiami Trail,
    delivery of total phosphorus  loads from
    the Everglades Agricultural Area is not
    limited just to the marshes above
    Alligator Alley (Figures 20 and 2 I). Total
    phosphorus loads in the canals are being
    transported south into the Park (Figure
    22).

       These  elevated  nutrient  con-
    centrations  are also indicated by the
    absence of an enzyme  (alkaline
    phosphatase)  released  by micro-
    organisms.  The enzyme is  produced
    only when  phosphorus concentrations
    in the water are so low that growth is
    limited (Figure 23). A latitudinal pattern
Figure 21. Water total phosphorus distribution in marsh from
north to south. Note:  50 ppb is the Phase I control target.
12

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                                                                South Florida Ecosystem Assessment Report
                        •|, IK
                                DRf SE*SC*J
                                 •  * '  '


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                             •       _  *
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                         .  •     TRAIL
                             -K] IB'  .Ifc.lK-  -IU&)  -111 411
                                                       -B: III  -m.pl  .illii.ii  -Sl> i
                     Figure 22. Pattern of marsh water total phosphorus concentrations.
                     Note: Hot spots near EAA, the Refuge, and the Park.

       •a i to
         LONGITUDE.
Figure 23. Microbial enzyme patterns.
High enzyme values imply low phosphorus
concentrations in water.
                   exists from north to south across the marsh and also indicates the clean
                   interior of the Refuge.
MERCURY CONTAMINATION
   The REMAP program was initially designed to
address mercury contamination  in South Florida.
Mosquitofish were selected as the  indicator fish
species because the fish are common throughout the
marsh and canals, can  be  easily collected at all
sampling sites, and are in the food chain for wading
birds and sport fish. Largemouth bass are the popular
sport fish and have high mercury concentrations, but
are not found at every site, are more mobile, and
are difficult to consistently collect in the marsh.

   Once mercury enters  the food chain, it increases
in concentration or biomagnifies at each  higher step
or level in the  food  chain. The highest mercury
concentrations are usually found in top predator fish
(e.g., largemouth bass), birds, reptiles,  and mammals
                                                                                                              13

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              South Florida Ecosystem Assessment Report
 Fish Hg100-250 ppb
 (43%)
                                     Fish Hg> 250 ppb
                                                (25%)
                                                                                    Fish Hg> 250 ppb
                                                                                               (4%)

                                                                                        Fish Hg 100-250 ppb
                                                                                                     (13%)
                        Fish Hg< 100 ppb (32%)
Figure 24. South Florida marsh (area-weigted)
mosquitofish mercury concentration distributions.
                                                        FishHg<100ppb
                                                        (83%)
                                                  Figure 25. South Florida canal mosquitofish
                                                  mercury concentration distributions.
  31B5
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                          that eat fish or fish-eating animals (e.g. raccoon, Florida panther). A predator
                          protection  level of 100  ppb mercury has been proposed by the US Fish
                          and Wildlife Service and can be used as a criterion for comparison among
                          systems and to determine potential exposure of largemouth bass and other
                          fish-eating animals to  mercury.
   In contrast to phosphorus, the highest mercury
concentrations  are found  in the marshes and not
the canals. Over half the  area in the  marsh (68%
or over   million acres) has mosquitofish with
mercury  concentrations that exceed  I 00 ppb
(Figure 24). About  17% of the canal  miles (about
 30 miles)  have mosquitofish  with mercury
concentrations that exceed the proposed predator
protection level of 100 ppb (Figure 25). The  highest
concentrations of methylmercury (the form of
mercury concentrated in the food chain) are found
not only in fish and  birds (Figure 26), but  also in
a gae in the  marsh  between Alligator Alley and
Tamiami Trail. The  concentration of mercury in
marsh mosquitofish  is significantly higher than the
concentration found  in canal mosquitofish (Figures
27 and 28).
                                   Me
                                       laaa
                                  OH H-o
Figure 26. Hot spot is the same for total mercury in
mosquitofish and great egret feathers.
14

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                                           South Florida Ecosystem Assessment Report
 The highest mercury concentrations in algae,  fish,  and Great Egrets all  co-occur
 in Water Conservation Area 3 between Alligator Alley and Tamiami Trail.
   The  marshes are the primary
areas of mercury contamination.
For methyl mercury to be formed,
exactly  the right combination of
environmental conditions must
occur.  Under the right set of
conditions of temperature, total
phosphorus, tota organic carbon,
sulfate, and pH, inorganic mercury
is converted by microorganisms to
methylmercury.  This  methyl-
mercury enters the food  chain
primarily through bioaccumulation
by algae, bacteria, and other tiny
organisms that are eaten by larger
organisms. The right combination
of environmental conditions occurs
between Alligator Alley  and
Tamiami Trail (Table I). Above
Alligator Alley, the organic com-
pounds and reduced sulfate (sulfide)
might bind the mercury or methyl-
mercury so it is not available for
uptake   by  organisms. Below
Tamiami  Trail,  lower  concen-
                                                          Marsh
                                          Average Mosquitofish Mercury Concentrations, ppb
                                                o                  ioa
                                                                                     :: :
                                       North of
                                   Alligator Alley

                                 Alligator Alley to
                                   Tamiami Trail

                                       South of
                                   Tamiami Trail
                                 Figure 27. Marsh mosquitofish mercury distribution from north to
                                 south. Note:  100 ppb is proposed predator protection level.

                                                         Canals
                                         Average Mosquitofish Mercury Concentrations,  ppb
                                               0                  i Oil                2 DO
                                       North of
                                   Alligator Alley

                                 Alligator Alley to
                                   Tamiami Trail

                                       South of
                                   Tamiami Trail
                                 Figure 28. Canal mosquitofish mercury distribution from north
                                 to south.  Note: 100 ppb is proposed predator protection level.
                                        Table 1
            Average Marsh and Canal Water Quality in Three Everglades Zones
                                    North of
                                 Alligator Alley
                                Marsh     Canal
Constituents

Total Phosphorus, ppb (ug/L)      20         78

Total Organic Carbon, ppm(mg/L)  25         26

Sulfate, ppm (mg/L)               9         27

Methylmercury, ppt(ng/L)         0.6        0.2
 Alligator Alley        South of
to Tamiami Trail    Tamiami Trail
Marsh     Canal    Marsh     Canal
 16

 17

  4
0.4
24
18
7
0.2
12
15
3
0.2
14
11
8
0.1
                                                                                        15

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              South Florida Ecosystem Assessment Report
                         trations of sulfate and total phosphorus are likely to limit the  microbial
                         methylation and organic production rates, respectively. Between Alligator
                         Alley and Tamiami Trail, the concentrations of organic compounds and
                         sulfide  have decreased and probably no longer compete  with the
                         microorganisms for mercury. In addition, phosphorus delivered from the
                         canals to the marsh in low concentrations  may stimulate the growth  of
                         periphyton mats. Periphyton are attached algae common in the Everglades
                         ecosystems. The  USGS has found methylating bacteria associated with
                         these mats.

                            Increased production  of algal mats may result in increased
                         methylmercury production.  This  methylmercury then increases  in the
                         food  chain from algae up to  wading bird nestlings and higher food chain
                         levels. The highest bioaccumulation in  mosquitofish  occurs  between
                         Alligator Alley and Tamiami  Trail  in both the canal and marsh habitats
                         (Figures  27 and 28).  However,  mosquitofish  also have high  mercury
                         contamination in  the  marsh south of Tamiami Trail  in the Park (Figure
                         27).  For methylmercury to accumulate up the food chain,  the right
                         combination of environmental conditions must exist and a complete food
                         chain for increased biomagnification at each level (Figure 29). The food
                         chain in the canals above Alligator Alley may not be sufficiently  complete
                         to accumulate mercury to concentrations above the predator protection
                         levels because of  increased eutrophication.

                                            Mercury Bioaccumulation
16
                    Figure 29. Bioaccumulation of mercury up the food chain from the water to wading birds and
                    the Florida panther.

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                                             South Florida Ecosystem Assessment Report
HABITAT ALTERATION
   One of the greatest human impacts in South  Florida has been to the
natural habitat. Over 50% of the historic Everglades wetlands have been
drained. In addition to habitat loss, there has also been significant alteration
of the remaining habitat. Because  of eutrophication,  about 4% (over
77,000 acres) of the Everglades  is now  cattail marsh (Figure 30). At the
turn of the 20th century, less than 1% of the marsh area was cattails.
                       Wet Prairie (46%)
                                          Cypress (5%)
                                          Pond(1%)
                                       Cattail (4%)
             Sawgrass (44%)
             Figure 30. Current distribution of marsh types
             found in the South Florida Everglades.
   Study results indicate that the  Everglades marsh habitat (Figure 30)
consists of 90% sawgrass and wet prairie communities and 4% cattail. As
ecosystem  restoration efforts proceed, such as phosphorus control or
modifications to hydropattern, these relative  habitat percentages can be
monitored  to assess the effectiveness  of restoration efforts.  Decreased
percentages of cattail  marsh can indicate decreased nutrient loading and
decreased eutrophication. Changes  in the percentages of different habitat
types can also indicate an increase or  decrease in the spread of exotic
species,  such as the  melaleuca tree.  There are other  project habitat
indicators that also provide information on other restoration issues (e.g.,
percent dry area).
                                                                                           17

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              South Florida Ecosystem Assessment Report
                         HYDROPATTERN MODIFICATION
                            The greatest change that has occurred in the Everglades ecosystem is
                         the change in surface water depth, distribution, and timing. The original
                         intent of the canals and levees was to "drain the swamp" so it could be
                         used for agricultural production and urban development. A comparison
                         of a model simulation  of the natural marsh water depth during a dry
                         season for the study area is shown  in contrast to  the actual measured
                         water depths  in the study area in April  995 (Figure 3 I). Changing water
                         depth also can significantly impact plants  and animals. Wading birds, for
                         example, might not be able to forage because  of increased depth while
                         some fish species lose habitat because depths are too shallow. The present
                         ponding of water in WCA-3A may influence the methylation of mercury.
                         The cornerstone to Everglades restoration is hydrologic restoration.
                         Without some semblance of the natural  hydropattern in  South  Florida,
                         the River of Grass and Big Cypress are unlikely to be protected or restored.
              Ecological Restoration requires Hydropattern Restoration.
                                                    LOWGITO&E,!
                             Figure 31. Comparison of current (left) vs. simulated natural marsh (right)
                             water depths for the study area.
18

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                                 South Florida Ecosystem Assessment Report
ECOSYSTEM RESTORATION TOOLS
   Multiple tools  are  required  to  resolve multiple  interrelated
environmenta  issues. A  number of tools are being used as part of the
Everglades ecosystem restoration efforts, including  mathematical models.
To investigate the mercury contamination problem, for example, US EPA
has two models that are  currently available. The Marsh Screening Model
(Figure 32) is a large-scale Everglades  ecosystem model with relatively
simple mercury cycling formulations that can be used to screen different
policy and/or management scenarios and evaluate their potential effects
on reducing mercury contamination. A second model,  BASS, is a  food
chain model that provides insight  on  how mercury  is  bioaccumulated
through the food chain. BASS provides  insight into the potential effects of
mercury on critical food chains
within the Everglades ecosystem.
US EPA  is  also developing a
dynamic mercury-cycling model,
MERCS.

   Other tools have been devel-
oped by other agencies and  are
being used to address important
environmental issues,  such as
hydropattern modification. The
South Florida Water Management
District, for example, has devel-
oped several hydrologic models
that are  being used to  evaluate
different management approaches
for restoring the natural hydrology
to the Everglades. One  of these
models  is called the  Natural
System  Model. The  Natural
System Model provides estimates
of what the hydrology might have
been under various meteorological and climatic conditions before major
drainage efforts  began (Figure 3  ). A second hydrologic  model simulates
current conditions within the marsh ecosystem and provides a tool for
                                                          Flow
                      Figure 32. Schematic showing the marsh screening model network.
                                                                         19

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              South Florida Ecosystem Assessment Report
                                                     evaluating the effects of different flood
                                                     control  and water supply management
                                                     options on marsh hydrology. By using both
                                                     models  and comparing and contrasting
                                                     their output, managers can better assess
                                                     which management  approaches offer
               Figure 33. Waste incinerators are one of the    °Ptimal  restoration options.
               sources of atmospheric mercury.
                            Other agencies also have developed tools that are being used in the
                          Everglades  ecosystem  for different  issues,  such as eutrophication,
                          atmospheric emissions,  habitat alteration, and other problems. While
                          mathematical modeling is one technology that is being pursued, this is
                          not the only set of tools in the toolbox.  Improved and innovative field
                          sampling techniques, more precise analytical procedures and use of remote
                          sensing and  satellite imagery are being used to investigate these issues.
                          The US EPA, for example, conducted a major study to investigate mercury
                          emissions from municipal and  medical waste incinerators (Figure 33) and
                          a coal-fired cement kiln. They are in the process of evaluating the fate and
                          transport of this mercury and its possible deposition over the marsh (Figure
                          34). The State of Florida, the  Electric Power Research Institute, and the
                          US EPA established a deposition monitoring network to determine the
                          atmospheric mercury forms  and  potential  deposition to  the marsh
                          throughout South Florida. The  USGS  is  conducting mercury
                          biogeochemical  and bioaccumulation  process studies.  Modeling,
                          monitoring,  and process studies are complementary tools for addressing
                          Everglades ecosystem issues. All of these tools and their information must
                                                              be integrated to develop man-
                                                              agement approaches that will not
                                                              only  restore and protect the
                                                              Everglades  but  also satisfy the
                                                              different societal demands for
                                                              water  supply,  flood  control,
                                                              agriculture,  and urban  devel-
                                                              opment.
                                                           I
               Figure 34. Fate and transport of mercury emissions from
               the source to the atmosphere and then deposited over the
               marsh.
20

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                                               South Florida Ecosystem Assessment Report
POLICY AND MANAGEMENT IMPLICATIONS
         WATER QUALITY
           Mercury
           The current water tota mercury criterion for protection
         of aquatic life is  2 parts per trillion (ppt). One  hundred
         percent of the  Everglades marsh has total  mercury
         concentrations less than 12  ppt. This criterion, therefore,
         is under-protective  because wildlife effects have been
         observed and  00% of the  Everglades is under a human
         health fish consumption advisory. In addition, the predator
         protection criterion  for mercury  in prey species of  00
         ppb  proposed  by the US  Fish and Wildlife Service is
         exceeded in over 65% of the marsh area. This indicates that alligators,
         raccoons, otters, endangered wading birds, other fish-eating animals, the
         Florida panther, and  humans are at risk from  mercury contamination.
            Figure 35. Wet deposition of mercury during
            storms is a major source of mercury to the
            marsh.
                The current chronic mercury aquatic life criterion is underprotective.
           Mercury Load ings
           South Florida Water Management District monitored total mercury
         concentrations biweekly at the pumps located on the canals surrounding
         the Everglades Agricultural Area. Atmospheric deposition monitoring data
         were collected at seven locations throughout South Florida. The data
         from these two monitoring programs were  used to estimate the annual
         total mercury loads to the Everglades ecosystem (Table 2). Atmospheric
         deposition in precipitation (Figure 35)
         contributed from  35 to 70 times the
         mercury loading  to the fresh water
         Everglades  compared to Everglades
         Agricultural Area stormwater. It is not
         known  what  proportion  of this
         atmospheric deposition is of natural
         versus anthropogenic origin. Atmos-
         pheric mercury source apportionment
         studies are scheduled for the next 4 to
         5 years.
                 Table 2
       Comparison of Atmospheric vs.
       Surface Water Mercury Loading
Year

1994

1995
Atmospheric
 Deposition
   (Ka/vrl

    140

    140
EAA Water
Discharge
  (Ka/vrl
                                                                                       21

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              South Florida Ecosystem Assessment Report
Figure 36. EAA stormwater discharge
contributes nutrients and mercury.
Phosphorus
   The Phase  interim phosphorus control target has been
established at a maximum of 50 ppb. However in  1995,
97% of the marsh had total phosphorus concentrations
less than 50 ppb. In addition, over 88% of the marsh had
total phosphorus concentrations less than 25 ppb or half
the Phase   total phosphorus control target.  Discharges
from the  Stormwater Treatment Areas at 50 ppb will
continue to increase Everglades eutrophication (Figure 36).
    Discharges from the  Stormwater Treatment Areas  at 50 ppb will continue
    to cause Everglades eutrophication.
                            Phosphorus-Mercury Interactions
                            The increased phosphorus concentrations measured in the Refuge,
                         the Everglades Water Conservation Areas, and the Park are above natural
                         background concentrations and may aggravate the mercury problem by
                         increasing the biomass of the periphyton mats in which additional mercury
                         methylation might be occurring. Recent studies by the USGS have indicated
                         that periphyton mats and  associated microbial communities might serve
                         as methylation sites for mercury.  Because the historic Everglades were so
                         nutrient-poor, there is a clear relationship between increased phosphorus
                         and eutrophication, which can result in increased plant biomass, including
                         periphyton. The effects of increased phosphorus cascade through the
                         ecosystem affecting  more than just plant  biomass. When  production
                         exceeds some critical threshold, organic matter can bind mercury, making
                         less  mercury  available  for methylation. In addition,   if oxygen
                         concentrations go to zero because of decaying organic matter, sulfide can
                         be released that also binds mercury. Process and food web studies are
                         required to further define the  driving factors and associated environmental
                         conditions.
22

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                                                         South Florida Ecosystem Assessment Report
               AIR QUALITY
                  Based on the deposition monitoring (Figure 37), emission studies,
               and an emissions inventory, the average mercury emissions for South
               Florida are about  3 times  higher than the state average.  In South
               Florida, the mercury deposition from precipitation downwind of the
               urban area is about 2 to 3 times the background level. The emission
               source studies indicate that municipal and medical waste incinerators
               are the major atmospheric mercury emission sources in South Florida.
               The portion of deposited mercury that comes from local sources has
               not been determined. However, additional studies to provide better
               estimates of natural mercury releases to the atmosphere are  in
               progress.
                                    Figure 37. Air depo-
                                    sition monitoring towers
                                    are located at 7 sites
                                    throughout South Florida.
                   Incineration,  not natural  sources, is the  primary source of atmospheric
                   mercury in South Florida.
            Hydropattern
            Modification
                        Eutrophication
                    Merc LJ ry
                    Cycling
              Endangered
                Species
Figure 38. Restoration issues are highly interde-
pendent and must be addressed together.
ASSESSING THE RISK
   US EPA Region 4 is in the process of
conducting a comparative  ecological  risk
assessment to determine which of these
environmental  problems  place   the
Everglades ecosystem at greatest risk. The
comparative  assessment is critical because
none of the problems occurs independently
of the others (Figure 38). Hydropattern
modification  is a primary driver of all  the
problems,  but hydropattern  can  be
influenced by habitat alteration. Both of these
problems  influence eutrophication and
mercury  contamination  and  cycling.
Eutrophication,  through  phosphorus
               addition,  is apparently contributing to the mercury  problem, and all of
               these problems influence wildlife and the increased distribution of nuisance
                                                                                                     23

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              South Florida Ecosystem Assessment Report
                         exotic species. Assessing the risk to the ecological resources from the
                         multiple environmental threats in  South  Florida requires a common
                         reference frame for estimating the extent and magnitude of both the threat
                         and the ecological effects.  The US EPA Ecosystem Assessment Project is
                         the first and only study, because  of its sampling design and probability
                         samples, to provide a common reference frame for multiple environmenta
                         threats and effects.  The spatial patterns of soil depth, phosphorus, fish
                         mercury, and water depth, for example, represent the first such unbiased
                         snapshots  of the condition of the South Florida Everglades ecosystem.
                         The consistent and  comparable data  from this study are critical for a
                         comparative ecological risk assessment.  Continued monitoring through
                         time will  permit these comparative risk estimates to be refined,
                         contributing to better management decisions. In addition, the Ecosystem
                         Restoration Task  Force has identified restoration success indicators (Table
                         3). These  indicators can be built into the monitoring program and can be
                         used to evaluate different management  options for ecosystem restoration.
                                          Table 3
                     Example Ecosystem Restoration Success Indicators
   Problem
   Hydropattern Modification
   Habitat Alteration
   Eutrophication
   Mercury Contamination
   Endangered Species
Success Indicators
Reinstate system-wide natural hydropatterns and sheet flow
Increased spatial extent of wildlife corridors/greenways/flyways
Reduced phosphorus loading
Reduced top carnivore mercury body burden
Increased populations of threatened/endangered species
                            The greatest threat to the Everglades ecosystem, however, is assuming
                         the problems facing the Everglades can be managed independently from
                         each other.  These problems are often  interdependent and must be
                         addressed using holistic, adaptive management approaches. This forms
                         the foundation for the comparative ecological assessment of the relative
                         risks from each of the environmenta problems.

    Comparative ecological risk assessment is  a critical  element of adaptive
    management for ecosystem restoration.
24

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                                        South Florida Ecosystem Assessment Report
           ON-GOING AND FUTURE  STUDIES
   US EPA Region 4 has completed one full  cycle of canal and  marsh
sampling and is in the process of analyzing the information. This information
will be used not only to answer the seven policy-relevant questions (page
7) identified for  mercury, but also to answer similar questions related to
the other environmental problems threatening the Everglades ecosystem
(Figure 39).  While this information  provides a sound baseline for
preliminary answers to these questions, one of the wettest years on record
occurred during the field sampling effort. Additional monitoring is essential
to determine the variability in the baseline patterns from
season to season and the effect of this variability on future
management decisions. Additional monitoring will increase
our ability to make statements about subareas in  the
Everglades ecosystem under different water management
regimes and  will minimize the time required to detect
changes from adaptive management actions.  Monitoring
and iterative comparative ecological risk assessments should
continue over the next 3 years as scientific understanding
of the interactions among these problems develops.
 WARhlNI
 SP-.IIM hii liiuiil • h*
                urt 
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              South Florida Ecosystem Assessment Report
                           The US EPA, a member of the South  Florida Ecosystem Restoration
                         Task Force, is contributing to other studies being conducted as part of the
                         restoration  effort. This project  is  contributing to on-going mercury
                         biogeochemistry and bioaccumulation process studies being conducted
                         by the USGS. For example, the Region 4  Ecosystem Assessment Project
                         has identified critical study areas in South Florida where process research
                         is needed to better understand the interrelationships among hydropattern
                         modifications, nutrient additions, and mercury cycling in the Everglades
                         ecosystems. This project is also  providing complementary monitoring
                         information for simultaneous studies of atmospheric  mercury emission,
                         transport, and deposition in South  Florida.  In addition, the US  EPA is
                         working with the  SFWMD Everglades Nutrient Removal  Project and
                         Stormwater Treatment Area Studies, the  US Army Corps of Engineers
                         Central and Southern Florida Project Re-study, and Florida Department
                         of Environmental Protection studies. The first comparative ecological risk
                         assessment,  incorporating results from these efforts,  is  planned for late
                          997.
    The US  EPA Region 4 Ecosystem Assessment Project provides a critical
    framework and  foundation  for assessing  the effectiveness of Everglades
    ecosystem  restoration activities into the 21st century.
26

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