The Florida Everglades: Human-Environment Interactions

Located in Southern Florida and widely known as the “River of Grass”, the Everglades are one of the largest wetlands in the world. The ecosystem covers over 4,500 miles of slow moving waters. Water leaving the lake in the wet-season forms a slow-moving river 60 miles wide and over 100 miles long, but rarely more than a few feet deep, flowing southwards across a limestone shelf to Florida Bay at the southern end of the state (U.S. Geological Survey, 1999).

Originally the Everglades extended over 3 million acres from Lake Okeechobee to Florida Bay, and are currently referred to as the ‘historic’ Everglades. The northern 1 million acres were designated to the Everglades Agricultural Area (E.A.A.). The southern 1.5 million acres were dedicated in 1947 as the Everglades National Park (E.N.P.) (Exploring the Environment: Florida Everglades, 2005) (Fig 1).

A World Heritage site, an International Biosphere Reserve, and one of only three areas to be designated a Wetland of International Importance; the Everglades are home to an astounding array of wildlife, from alligators to bald eagles to black bears (Sierra Club, N.d.).

Importance of the Everglades

The Everglades ecosystems are important as a habitat for many unique species of micro-organisms, plants and animals, which have developed over thousands of years. The area is also relied upon by residents as a water supply. The Everglades, which combine climate, geographical location and ocean currents, are also America’s only sub-tropical wildernesses and visitors travel from all over the world to experience its natural beauty (Exploring the Environment: Florida Everglades, 2005).

In terms of human impact, farming and the continuous expansion of cities are essential in Florida. As early as the 1800’s people have affected the Everglades and within 100 years, more than half of the wetlands were lost due to development. In the past few decades people have begun to notice the environmental impacts of removing the Everglades ecosystem from South Florida. Currently private and government agencies are fighting to protect the area; however there are many complicated issues which need to be addressed first. Restoring the Everglades may ultimately mean a decrease in available water elsewhere for anthropogenic activities such as farming (McGinley, 2008). The linkages between the Everglades, Lake Okeechobee and the Kissimmee River, which provides 80% of the surface flow into Lake Okeechobee, illustrate the importance of connectivity among eco-regions to maintain integrity (WWF Report, 2001).

Past Management

Over the last one and half centuries, when major alterations to the Everglades began, there have been numerous cases of disturbances that have caused noticeable impacts ranging in scale, timeframe and type, in terms of social, economic and environmental. The once small indigenous population of South Florida drew a low-impact livelihood from the Everglades (Haman and Svendsen, 2006). Significant development began in the 1850s and really advanced in the early 20th Century through the promotion of land and water resources for agriculture, urban growth and industry (Anderson and Rosendahl, 1998). Large areas have been drained to expose rich soils for agriculture, with the headwaters in Lake Okeechobee subsequently diverted directly into the Atlantic Ocean and the Gulf of Mexico (Sklar et al., 2005). A major driver of change occurred as a result of WWI, which saw demand for agricultural products increase to fuel the economy. People were actively encouraged to farm the land.

Control significantly increased as a response to a disastrous series of floods and droughts throughout the 20th Century, resulting in the construction of large-scale infrastructure (Gunderson and Light, 2006). Hurricanes in 1926 and 1928 led to a major flood control project organised by the Army Corps of Engineers, who constructed a huge levee construction along Lake Okeechobee. By the 1940s, droughts and fires as well as further flooding and water demand led to continued water control through levees, canals and pumps.

The Central and Southern Florida Project for Flood Control was set up in 1948. The Everglades became compartmentalised into three land uses: agriculture (in the north), urban areas (in the east) and conservation (centrally and in the south). Water Conservation Areas (WCA) impounded by levees acted to convert the shallow, free-flowing wetlands into a division of reservoir compartments (Sklar et al., 2005). They were designed to protect agriculture from flooding and control water supplies, but led to a disruption of the natural hydropattern (the direction and spatial extent of flow) and hydroperiod (water depth, timing and duration) (Chimney and Goforth, 2006). Some areas have since experienced excessive flooding whilst others suffered from over-drainage.

In the 1960s/1970s a series of droughts occurred when management was preparing for flooding. By this point people began to realise that decades of management were simply not working. Water management has followed a pattern of growth, crisis and reformation (Gunderson and Light, 2006), with the increased application of hard-engineering structures as the continued response. This approach has been encouraged through the standpoint of optimal thinking; the continual search to maximise profits from the landscape at the expense of its long-term supporting capacity.

In 1983 the Everglades was subject to a period of heavy and sustained rainfall. The event caused severe flooding and resulted in demands for a new approach to water management and instigated a period of experimental approaches to delivering this at state and federal levels.

Up until this point it was not recognised that disturbances have effects beyond their scale and type and the system could not withstand these cross scale effects.

In 1992 congress passed a bill for the Army Corps to devise a plan to rectify the environmental damage caused by previous management (Mayer, 2001). A Comprehensive Everglades Restoration Plan aims to add water storage capacity and restore the delivery and timing of flows. Plans have been made for 18,000 ha of treatment wetlands to be created, allowing naturally occurring biological processes to reduce the runoff of nutrient loads into the Everglades (Chimney and Goforth, 2006). The Everglades Nutrient Removal Project has enabled the monitoring of such techniques on 1,544 ha of prototype wetland to prepare for the large-scale plans. A mandatory best management practices program has targeted reductions of nutrient loading in the Everglades Agricultural Area, with decreasing trends in phosphorus loads observed after 7-10 years of implementation (Daroub et al., 2009).

Scientists and policy-makers have shaped the way people have understood the Everglades environment and its consequent management policies (Meindl et al., 2002). We now understand that fundamental errors were calculated in how much water should have been removed from the landscape to make it agriculturally productive. There was also a failure to realise that although soils were highly productive, the system as a whole was nutrient poor (Walker and Salt, 2006), and so manipulation of the system for agriculture has led to shifts in its ecological functioning.

Threats and Trajectories

Water Quality: Runoff from the EAA travels directly into the WCAs through a series of canals (Chimney and Goforth, 2001) contributing to nutrient enrichment, causing eutrophication. Heavy metal contamination is also an issue, particularly regarding mercury.

Altered flow regimes: coupled with the impoundment of the WCAs, this has exposed areas to extremes of flooding and over-drainage, as well as having significant ecological impacts through reductions in wildlife and fish populations who depend upon the timings and durations of flows for foraging and reproduction (Perry, 2004).

Invasive species: 1.5 million acres of land has become infested with invasive species (Kranzer, 2003). Most significantly, nutrient enrichment has facilitated a shift in dominance from sawgrass (which prefers low-nutrient environments) to cattail (which is adapted to high-nutrient environments) (Walker and Salt, 2006) Attempts to kill cattail, through fire and stem damage, triggers its reproductive process (Serbesoff-King, 2003). Under low-nutrient conditions, when sawgrass was burned it was replaced by wet prairie communities which were then re-colonised by sawgrass. The sawgrass/wet prairie marshlands were resilient to fire disturbances under this regime but the invasion of cattail has instigated a loss of this resilience. This has had significant impacts on ecology. For example, there has been a 90-95% decline of wading birds.

Habitat and species losses: 50% of the historic Everglades has been lost and cannot be restored, while flows of water have been reduced by approximately 70% (Perry, 2004). There are now 68 federally listed endangered species, such as the Florida panther and the American crocodile.

Declining Fisheries: the region has already seen erosion and collapse of a few coastal creeks with the erosion activating stored nutrients in peat and mud soil which is taken up by micro organisms increasing the risk of eutrophication. Loss of sea grass from increased depth of water and salinity at Florida bay has already been seen, affecting the world class fisheries in the location (Friar, 2007).

Population growth: Over the past century, the population of the Everglades has grown from 10,000 to 6 million and is projected to double to 12 million by 2050 (Walker and Salt, 2006). The South Florida Water Management District (SFWMD) predicts an increase in water demand of 38% by 2010 (Mayer, 2001).

Climate Change: Sea level has been rising in Florida since the last ice age (10,000 yrs BP), increasing by 9 inches every 100 years up to 3,200 yrs BP when it dropped to 1.5 inches (Friar, 2007). 60% of park is less than 3% above mean sea level with the highest ground being 11 feet above. The IPCC report by Parry et al. (2007), modelled the impact using 6 different climate change scenarios, projecting a rise between 7-23 inches by end of the century, leading to a potential 10-50% of parks freshwater marsh being transformed to salt water marsh. The IPCC report predicts a 2-5oC temperature rise by 2100, with potential to increase algal blooms and marine diseases, as well as kill off sea grass.

Floods and droughts: The Everglades experiences a wide variation in climate due to tropical weather systems and regional shifts in weather related to the southern oscillation (Perry, 2008). The area is increasingly vulnerable to shocks from extreme weather events. Hurricane activity is predicted to increase and as well as its direct damage, indirect increases in freshwater discharge and nutrient enrichment can also result (Williams et al., 2008).

Fires: Over-drainage is likely to have contributed to the large number of severe fires throughout the 20th Century (Newman et al., 1998), which has contributed to the invasion of cattail.


Water quality is a key threshold in the Everglades system. The system was once oligotrophic but has in parts become hypereutrophic. Excessive nutrient loads have caused imbalances in the natural fauna and fauna. Management aims to reduce phosphorous levels below 50ppb to begin with and achieve 10ppb in the long term. 10ppb has been identified as the key point at which the Everglades’ biota can be protected (DOI, 2005).

Mercury contamination has been linked to agricultural practices and is toxic. Sulphur is a major control on mercury levels and discharge from the EAA is the driving force. Increasing the water flow to the Everglades may result in sulphur concentrations increasing and thus mercury. Current safe body burden concentrations are set at 0.3 mg/kg. At present all fish species are above this threshold (Alexrad et al 2005).

Regional runoff is now transported to the coasts through a canal system. The waters cause significant damage to coastal estuaries through contamination, eutrophication and salinity changes. Algal blooms are a result and produce toxins that harm marine biota and are a human health risk. There is a point at which the runoff contaminates can no longer be absorbed without risking damage to coastal waters and marine life. Transported runoff is therefore a key threshold within the Everglades ecosystem (Perry, 2008).

IPCC’s 2007 projections could lead to submerging of tidal flats and inland freshwater marshes impacting on wading birds and other species. A 23 inches rise would submerge the pinelands (one of the largest ecosystems in S. Florida aka Everglades Flatwoods). The IPCC projections may also lead to erosion of beaches leaving fewer habitats for nesting sea turtles (Friar, 2007).

Adaptive Management

The Millennium Ecosystem Assessment board (MEA, 2005) define adaptive management as a systematic process which utilises management as an experimental tool in order to learn lessons and improve future policies. Adaptive systems are dynamic and can change in response to perturbations and complex problems more effectively than “trapped” and rigid management structures (Gunderson and Light, 2006). These ideas are linked strongly to resilience, as in order to be sustainable, a system must have a certain level of resilience to survive shocks without changing dramatically. Systems controlled by rigid management structures are usually less capable of adapting to sudden changes and thus can hinder long term sustainability through processes of stagnation in policy and beaurocracy.

Current Management and Future Trajectories

Current management in the Everglades is focused on resolving past conflicts as opposed to seeking sustainability for the future (Gunderson and Light, 2006). The Everglades management paradigm adopts a scientific approach rather than an adaptive one (Brunner and Steelman, 2005). Gunderson and Holling (2002) state that the Everglades is in a “management trap”, fuelled by conventional bureaucratic systems in play which control financial infusion into the system. Gunderson and Light (2006) describe the management system as resultantly being itself very resilient, governed by rules and policies which are no longer appropriate to tackle the complexity of the problems at hand. Such a system has strongly discouraged experimental research which is feared may not necessarily produce meaningful results reducing the overall ability for managers to learn from mistakes made.

Presently, in order for policies to be accepted, managers must first be able to rigorously predict every potential outcome of the proposal. Innovation is often stifled through complex social and political pressures which dissuade the diversification of management strategy. An example of this occurred in 1983, where managers have trialled a “free flow” program of water distribution following a period of heavy rainfall. The project was developed as a test to investigate the requirement of such heavily regulated control of water supplies throughout the region. Light et al. (1989) describe how the project was cancelled within a year as a result of lawsuits filed by local stakeholders who were worried the new system would not serve their best interests. This has produced a resilient management structure which focuses primarily on reactionary hard engineering solutions to problems as they occur, as opposed to learning from experience and testing the waters to inform a longer term future strategy of conservation. Wesley et al. (2005) describes this mismatch between solution finding and problems as the most major obstacle for social innovation in management strategising.

Future Implications

Whilst the social and political systems have suffered from their resilient and rigid policies, the ecology has experienced a loss of its resilience which has led to a shift from sawgrass to cattail dominance. This indicates that the benefits of resilience depend on individual’s perspectives of the system being managed.

For the Everglades to become a resilient system, the thresholds that have been identified must be considered. Currently the pressures are too great for the ecological system to absorb the disturbance without significant change. Phosphorous and mercury concentrations are currently too great for the system to tolerate without significant change. It will take a considerable reduction in these entities to move to a more ecologically resilient state.

Management is now somewhat at a stalemate as so many constraints are placed on future actions that the system is unable to progress forward (Gunderson and Light, 2006). Management therefore currently lacks the encouragement to employ innovation through experimentation. The varying interests of numerous stakeholders and pressures from past failures restrict the system’s capacity to adapt.

The replacement of sawgrass with cattail provides a good example of how shifts are driven by processes working at varying spatial and temporal scales (Walker and Salt, 2006). Vegetation structures form the most rapidly changing variable with plant turnovers of approximately 5-10 years. Fires occur in cycles of 10-20 years while freezes and droughts occur at return times of several decades. Finally, soil phosphorus concentrations form the slowest variable with turnover times over centuries. Development of the Everglades must recognise it as a linked socio-ecological system, with a range of linked ecological and social cycles.

The Everglades are beyond a point where they can ever be fully restored. Management schemes now face the challenge of balancing restoration and conservation against meeting the requirements of water supply and flood protection for present and projected populations. To address this there is a need to move away from the rigid paradigm of scientific management towards a more adaptive and holistic approach.

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Works Cited

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Geary, T.F. and Woodall, S.L. 1990  Melaleuca. In Burns, R. M. and B. H. Honkala, Technical coordinators. Silvics of North America: 1.Conifers; Honkala, technical coordinators. Silvics of North America: 1.Conifers; Washington, DC. Vol. 2. [Online] Available:

Bodle, J. M., A. P. Ferriter and D. D. Thayer. 1994 The biology, distribution, and ecological consequences of Melaleuca quinquenervia in the Evergladesp. 341-355. In S. M. Davis and  Ogden J.C. (eds.). Everglades: the ecosystem and its restoration., St. Lucie Press, Delray Beach.

Diamond, C., D. Davis and D. C. Schmitz. 1991 Economic impact statement: the addition of Melaleuca quinquenervia to the Florida prohibited aquatic plant list, 87-110. In Center, T.D., Doren, R. F., Hofstetter R.L., Meyers R.L., and Whiteaker, L.D. (eds.). Proc. Symp. Exotic Pest Plants. National Park Service, Denver, CO

Chimney, M.J and Goforth, G. 2001 Environmental Impacts to the Everglades ecosystem: a historical perspective and restoration strategies. Water Science and Technology, 44, 93-100.

Ogden, L. 2009 The Everglades Ecosystem and the Politics of Nature. American Anthropologist. 110, 1, 21-32

Perry W.B. 2008 Everglades restoration and water quality challenges in south Florida. Ecotoxicology, 17, 569-578.

Smith, S, M., Gawlik, D, E., Rutchey, K., Crozier G, E. And Gray, S. 2003 Assessing drought-related ecological risk in the Florida Everglades. Journal of Environmental Management. 68, 355–366.

DOI and USACE (Department of Interior and US Army Corps of Engineers). 2005 Central and Southern Florida Project Comprehensive Everglades Restoration Plan: 2005 Report to Congress. Washington, DC USA. [Online] Available:

Axelrad D, Atkeson T, Pollman C, Lange T, Rumbold D, Weaver K. 2005  Chapter 2B: Mercury monitoring, research and environmental assessment in South Florida. In South Florida Environmental Report. South Florida Water Management District, West Palm Beach, Florida, USA. [Online] Available:

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