Everglades National Park

South Florida Natural Resource Center

Research Programs and Projects

The information presented on this page was transcribed directly from the South Florida Research Center's report, "Research in Everglades National Park".

  1. Hydrology Program
  2. Marine Program
  3. Vegetation Program
  4. Wildlife Program
  5. Shark Slough Restoration
  6. Nutrient Enrichment
  7. Taylor Slough/ C-111 Basin Restorations
  8. West Dade Wellfield Impacts
  1. Florida Bay Wildlife Population Trends
  2. Endangered and Indicator Species Studies
  3. Exotic Plants
  4. Fire Management Program
  5. Seagrass Die-off in Florida Bay
  6. Fish Kills in Florida Bay
  7. Fisheries Harvest
  8. Widening of Highway 1

The Hydrology Program

The Hydrology Program monitors the quality and quantity of surface and ground water within the park to characterize current hydrologic conditions. Hydrological research evaluates the impacts of upstream water management on the park's water resources, and provides information necessary to develop hydrologic restoration alternatives to mitigate against environmental damage. Current areas of intense interest are development of more "natural" water delivery regimes and determination of the optimum quantity of water necessary to restore ENP. Research hydrologists collaborate with other water management agencies to coordinate and accomplish overall Everglades hydrological objectives.

The Marine Program

The Marine Program is designed to monitor biological conditions and water quality in marine and estuarine systems in the park. Marine research conducts studies on specific resource issues such as impacts of upland water management on marine plant and animal communities, the status of gamefish stocks, identification of critical habitat for juvenile fish and invertebrates and the role of disturbance in the system. For example, the recent die-off of seagrass in Florida Bay and general water quality in the Bay are priority areas. Program staff apply these findings to the management of marine resources in the park.

The Vegetation Program

The Vegetation Program must provide the research necessary to understand the dynamics of the park vegetation, which includes:

  1. Describing and analyzing the Everglades communities and their changes over time and their change as a result of water management practices
  2. Determining the effects of fire on plant communities
  3. Managing and controlling exotic plants threatening the Everglades
  4. Determining the effects of changes in water quantity and quality on park vegetation communities.
The program is severely underfunded and understaffed at present. This program receives ranger division assistance in carrying out programs of prescribed fire management and exotic plant removal.

The Wildlife Program

The Wildlife Program conducts research to discern inter-relationships and dynamics in the wildlife of the Everglades system. It measures environmental relationships and long-term population trends for the park's wildlife, including threatened species and indicator species such as wading birds, alligators, freshwater fishes and the Florida panther. Studies focus on relationships between animal populations and water management practices. Much of the wildlife program is designed to provide the technical information needed for the development of a longterm Everglades restoration program.

Shark Slough Restoration

The only remaining option for recovering the biological vitality that formerly characterized Everglades National Park will be to implement an extensive, ecological restoration program. The Everglades ecosystem has experienced large-scale alternatives in spatial, extent, and temporal hydrological patterns that, while dating back to the beginning of this century, have occurred at an accelerated pace sine the 1950's. Although a wide variety of Everglades animals have been adversely impacted, those populations with relatively large spatial requirements in the ecosystem, or that are high in the aquatic food chains, have been most seriously damaged. Thus, the number of nesting wading birds on the mainland of the park has declined by about 95 percent since the 1930's, and the region can now claim an impressive list of endangered, threatened, or severely stressed species, including the Florida Panther, Round-tailed Muskrat, Wood Stork, Snowy Egret, White Ibis, Snail Kite, Osprey, Limpkin, Cape Sable Sparrow, American Crocodile, and American Alligator. The working hypothesis for the restoration program is that a return to natural hydrological conditions in the wetlands within the Everglades National Park and in adjacent wetlands upstream from the park, in terms of volume and quality of water, timing of surface water flows, and distribution and duration patterns of flooding, will result in a substantial recovery of many characteristic and endangered species in the region. The park is currently working with the Army Corps of Engineers and the South Florida Water Management District to authorize and implement a series of structural and operational changes in water management practices that will be required if we are to achieve the desired hydrological and ecological restoration goals.

Nutrient Enrichment in the Everglades

Everglades wetlands are very sensitive to water quality perturbations and require nearly pristine water in order for preservation intact of native flora and fauna and maintenance of ecological integrity. Water discharged into the public Everglades Water Conservation Areas, including Loxahatchee National Wildlife Refuge, is nutrient-laden compared to natural Everglades water quality. The result of this practice over the last several decades has been well documented nutrient-induced biological changes to these public wetlands. These changes are ecologically systemic and constitute a loss of thousands of acres of native Everglades habitat. Indications of nutrient-induced damage to Everglades National Park have also been documented, as have statistically significant increases in the concentration of phosphorus delivered to the Park since 1977. A lawsuit was filed in October 1988 by the U.S. Department of Justice alleging that two State agencies, the Florida Department of Environmental Regulation and the South Florida Water Management District, have failed to enforce state law and water quality standards, and have failed in their regulatory responsibility by allowing the continued delivery of degraded waters to lands administered by the Department of Interior. Trial date for the suit is set for September 1991 in federal court. The ongoing litigation is now in the midst of an intensive discovery process.

Taylor Slough/C-111 Basin Restorations

The hydrology of the Taylor Slough and C-111 Basins has been modified by upstream drainage and the diversion of excess wet season water into the C-111 canal and, subsequently, into the downstream estuaries. The alteration of natural hydroperiods is particularly apparent in the headwaters of Taylor Slough where lower water levels have been exacerbated by drawdowns in the L-31W canal. Restoration of wetlands in these basins and the reduction of damaging discharges into the downstream estuaries require major structural and operational changes in the South Dade Conveyance System. Following the catastrophic C-111 canal discharge into Manatee Bay and Barnes Sound in August 1988, the South Florida Water Management District designed and implemented the C-111 Interim Plan allowing for controlled discharge into these estuaries and increased freshwater flow into Florida Bay. The Army Corps of Engineers is now beginning the process for making structural and operational changes to the C-111 canal. Park research staff and SFWMD staff are participating in this effort. Current goals are that excess water be released into northern Taylor Slough and the C-111 Basins including Florida Bay, thus negating the need to release unwanted water into downstream estuaries directly via the C-111 canal. This ongoing process represents an important opportunity for restoration of more natural hydrologic conditions in Taylor Slough, the C-111 Basins and Florida Bay.

West Dade Wellfield Impacts

Dade County is experiencing rapid population growth which has placed increased demands on the municipal water supply system. In response, Dade County is designing a 140-million-gallon-per day wellfield which will be located in the western portion of the County adjacent to Northeast Shark Slough. Pumpages of the proposed wellfield are expected to produce drawdowns that will impact water levels in the wetlands along the edge of Northeast Shark Slough. Reduced water depths and/or shortened hydroperiods may negate much of the restoration efforts of the current Shark Slough water delivery experiments. Increased surface water diversions from Water Conservation Area 3A will also be needed to maintain canal stages in the areas adjacent to the proposed wellfield. The higher canal stages are necessary to reduce the lateral extent of the drawdowns into developed areas of the County which have the potential for water quality degradation. The impacts of these surface water diversions on water deliveries to Everglades National Park and the developed areas of the lower East Coast need to be evaluated.

Florida Bay Wildlife Population Trends

Since the late 1970's, information from a mix of wildlife studies and censuses in Florida Bay has presented an unsettling picture of an ecosystem where all is not well. While Bald Eagle and American Crocodile numbers and reproduction rates have looked good, the number of nesting Ospreys has significantly declined, and reproductive rates by Great White Herons nd Roseate Spoonbills may also have been reduced. The cause for the relatively sharp decline in Ospreys is unknown, while reproductive problems by spoonbills may be due to the affects of unnatural water deliveries from C-111 into the bird's major feeding grounds. The current level of information for these and other larger vertebrates in the Bay, however, is for the most part inadequate for an assessment of the magnitude and nature of the problem(s). A systematic censusing program for several key indicator species is called for, as a basis for selecting more intensive studies where problems are confirmed.

Endangered and Indicator Species Studies

The Park's research staff is currently conducting or supporting a series of long-term studies and inventories of an array of key species in the Everglades ecosystem. Species included in this program are several that are classified as endangered: Manatee, Florida Panther, Wood Stork, Bald Eagle, Snail Kite, American Crocodile, and the sea turtles; or that are important indicators of the wetland ecosystems: wading bird populations, the American Alligator, and the freshwater fish community. We study these species both to understand the habitat requirements of each in the Everglades region, and to understand long-term changes in the components and functions of these ecosystems. Much of our ecosystem management and restoration programs are based upon an understanding of the impacts that water management practices have had on the Everglades and Florida Bays systems, which we have learned through these species studies.

Exotic Plants

Everglades National Park has over 200 exotic pest plant species occurring in every plant community. The major problem species are Melaleuca quinquenervia, Schinus terebinthifolius, and Casuarina spp. Everglades is currently involved in an interagency project with Dade County to control Melaleuca in the East Everglades acquisition area, and a wetland restoration project to control Schinus in the Hole-in-the-Donut.

Fire Management Program

Everglades National Park contains many fire adapted plant community associations. These communities have, in the past several decades, been subject to numerous human-caused fires, both prescribed and wild fires, during seasons that are not considered appropriate for the maintenance of these ecosystems. The Everglades Fire Management staff and the SFRC are engaged in evaluating the prescribed burn program to adjust the burn regimes to more appropriate early wet season burns (April through June).

Seagrass Die-Off in Florida Bay

Seagrasses, primarily turtlegrass, Thalassia testudinum, have been dying since the summer of 1987 in western Florida Bay. Since then, an estimated 20,000 acres of seagrass bottom have been denuded and an additional 60,000 acres have been impacted to a lesser degree. Some recolonization by shoal grass, Halodule wrightii, is occurring. The loss of seagrass habitat on this scale is unprecedented in tropical seagrass systems. An analogous situation has been observed only once previously, that being the eelgrass wasting disease of the 1930Õs. At that time eelgrass disappeared over much of its range along the east coast of the United States and in Europe. Severe habitat alterations, species disappearances, and declines in fisheries were attributed to the decline of this seagrass.

Seagrasses form the basis for the ecology of Florida Bay by:

  1. serving as the dominant primary producer;
  2. supporting both grazing and detrital food chains;
  3. providing shelter for animals;
  4. stabilizing sediments; and
  5. influencing nutrient relationships.

Park research staff of the South Florida Research Center have joined with scientists from the Florida Department of Natural Resources, the University of Georgia, the University of Virginia and Florida International University to study the problem. Research to date suggests that the synergistic effect of several naturally stressful factors (lack of hurricanes, relatively high fall water temperatures, overly mature seagrass beds) have resulted in a production/respiration imbalance causing seagrass to die. By-products of the decomposition of dead seagrass and the loss of the plant canopy have promoted poor water quality and increased epiphytic algal growth encouraging continued die- off.

Fish Kills in Florida Bay

Florida Bay is an extensive, poorly mixed, shallow water estuary prone to hypersalinity. Systems exhibiting these characteristics can be highly stressful for fish because water conditions respond rapidly to changes in atmospheric conditions. Fish living in Florida Bay regularly experience environmental extremes which occasionally result in fish kills. Records of fish kills occurring in the estuaries of Everglades National Park date rom 1944 and include 33 known fish kills; undoubtedly others have occurred. Typically fish kills are caused:
  1. by rapid drops in water temperature associated with winter cold snaps; or
  2. by stress related anoia associated with high temperatures, large rainfall events, extreme low water, or combinations of these factors.
Additionally, fish kills in Florida Bay are caused by special events such as the freshwater release from the C-111 canal in August 1988. At this time there is no substantive evidence suggesting that a fish kill in Florida Bay has resulted from the discharge of a ŮpollutantÓ.

Of the 33 reported fish kills, 7 occurred between the months of December and January associated with the passage of cold fronts through south Florida. The remaining 26 fish kills occurred between the months of March and November and probably resulted from anoxia due to localized environmental extremes. Half of these fish kills occurred in the fall (September to November); fall is a period of relatively high natural stress because primary production declines with day length while water temperature remains relatively high keeping plant respiration high.

This past year has been noteworthy in terms of the number of significant fish kills occurring in Florida Bay. Last Christmas a cold snap killed fish throughout Florida Bay and this summer and fall 3 fish kills occurred in the Rankin Lake area east of Flamingo. This region of the bay has, for years, been the site of numerous large fish kills probably because it is several square miles in extent and extremely shallow, averaging less than a foot. When environmental extremes suddenly occur fish can not escape. Currently severe seagrass die-off is present in the Rankin Lake area and is exacerbating this naturally stressful situation. The frequency of fish kills in this area and their severity can probably be attributed to the poor water quality and the tremendous plant decomposition associated with seagrass die-off.

Fisheries Harvest

Everglades National Park is the site of a large recreational sport fishery. Commercial fishing was present in the bay uyntil 1985. Beginning in the miod to late 1950's the University of Miami developed and maintained a fishery harvest monitoring program in the park. South Florida Research Center staff have continued this work since the early 1970's. The database which has been developed over the years is one of the finest in the country and currently contributes significantly towards fishery management in Everglades National Park, the State of Florida and the Gulf of Mexico.

The number of recreational sport fisherman in the park grew at an annual rate of approximately seven percent per year from 1979 through 1987. Typically about 45,000 recreational fishing trips are made in the park each year. Current harvest by sport fishermen exceeds 385,000 fish each year. The primary species being harvested continue to be gray snapper, spotted seatrout, red drum and snook. Increased catches of black crum, sheepshead, tripletail and Jewfish have been reported. Recently a 10 inch size limit was established for the gray snapper and may have resulted in heavier harvest of other species such as sheepshead. The two year statewide closure of the red drum harvest has not resulted in the "comeback" for this species which was expected. Currently a seasonal closure, a bag and size limit are in effect for the red drum. Snook harvest is stable but well below the 1985 peak.

Widening of U.S.Highway 1

The Florida Department of Transportation is currently in the active stages of planning for improving and widening U.S. Highway 1 between Florida City and Key Largo. The need for evacuation of the Florida Keys during hurricanes has given this project a high priority. Since the Florida East Coast Railroad first reached Key Largo around the turn of the century it has been recognized that its road bed (now U.S. 1) had impacted the ecology of this region. These impacts include: disruption of the natural hydrology of the marshes south of Florida City and in northeast Florida Bay; fragmentation of natural wetlands and vehicle related impacts to wildlife. Wildlife in the vicinity include several Federally listed endangered species such as the American crocodile and the Florida panther. Park research staff are actively working with FDOT in identifying and insuring that these environmental considerations are incorporated into the finished highway.

This page is designed and maintained by:

Project Director
Everglades Information Network & Digital Library
Florida International University Libraries

Copyright © 1996. All rights reserved.
Illustrations copyright © 1995 by Wendell Minor from Everglades
by Jean Craighead George, HarperCollins Children's Books,
and included on this site with the express permission of the publisher.