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Studies and Monitoring

Everglades National Park

Everglades National Park (NP), Florida, has its own unique environmental concerns based on its particular ecology. Air quality studies and monitoring programs at Everglades NP focus on mercury deposition and effects. Click on the tabs below to review air quality studies and key scientific references at Everglades NP, as well as to access information on air quality monitoring in the park.

  • Studies & Projects
  • Monitoring & Data
  • Key References

Ongoing research in Everglades NP, Florida:

Mercury and the Endangered Florida Panther

The Florida panther (Puma concolor coryi), a state and federally-listed endangered species, has suffered severe declines in population numbers because of environmental stressors, low genetic variability, and habitat loss. Mercury contamination continues to be a suspect in the species’ poor reproductive success. Detectable levels of mercury in panthers and strong spatial gradients have been evident from surveys dating back to 1978, with the highest levels found in panthers from the Shark River Slough of Everglades NP (Roelke et al. 1991). The spatial gradients were reconfirmed more recently (Brandon et al. 2009), and Everglades NP continues to have the highest mean concentrations of mercury in panther hair and blood of all four South Florida regions studied (SFER 2011). Also, mercury in panther hair samples from the 1990s was significantly higher than in museum specimens dating back to the 1890s (Newman et al. 2004). A study in the early 2000s concluded that the risks to panthers from mercury exposure had decreased somewhat from the 1990s (Barron et al. 2004), likely because of better controls on sources of airborne mercury. However, there is evidence that high mercury-level regions in the Everglades continue to exist or could increase because of marsh restoration activities. The high mercury levels found in panthers in Everglades NP have been attributed to a preferential diet consisting predominantly of fish-eating wildlife, such as raccoons and alligators, rather than of herbivores, such as deer.

Mercury and Toxics Impacts

Everglades NP and the surrounding South Florida region have extremely high levels of mercury contamination. This is due in part to high rates of atmospheric mercury deposition from external and local sources, which include coal-burning power plants and waste incinerators, and also due in part to the area’s unusual environmental conditions. Mercury has been documented in many ecosystem components and different levels of the food chain at the park. Elevated concentrations in invertebrates, frogs, fish, wading birds, pythons, and alligators exceed environmental and human health thresholds (Guentzel et al. 1998; Krabbenhoft 2010; Rumbold et al. 2002; Rumbold 2005; Ugarte et al. 2005). Mercury contamination has been suspected in the death of some Florida panthers and attributed to high liver mercury levels (Barron et al. 2004; Roelke et al. 1991). Mercury in wading birds is at levels known to cause neurologic and reproductive impairment (Frederick and Jayasena 2010; Sundlof et al. 1994). Ongoing mercury research at the park continues to assess mercury cycling in the environment and accumulation in sediments, fish, and wildlife.

Other long-term studies on mercury in the Everglades NP include: Mercury Cycling in the Everglades (USGS) and the South Florida Mercury Science Program (Florida Department of Environmental Protection), and other initiatives by the state to work with industry and reduce mercury in the environment. The NPS also facilitates the ongoing monitoring of mercury in wet deposition at Everglades NP. find data »

Despite many scientific accomplishments in the last decade that have improved understanding about how mercury cycles in the Everglades marsh, a significant question remains: Why is mercury in Everglades NP’s biota much higher than in biota from most everywhere else in south Florida? The park continues to collect and provide tissue, feather, or unhatched egg samples from several species, and water and sediment samples, for mercury analysis to answer this question. Mercury monitoring at Everglades NP may also soon be expanded to include wading birds, such as the woodstork—a federally-listed endangered species.

Studies have been conducted on other airborne toxics, including endosulfan. Elevated levels of this agricultural pesticide in sediment, surface waters, and native fish in the Everglades and nearby Biscayne Bay, and in several western national parks, led to widespread public demands to ban endosulfan. EPA recently banned the chemical and is currently negotiating a phase out of endosulfan for all commercial and residential uses.

Air quality monitoring information and data access:

Air Pollutant/Impact

Monitoring Program

Sites and Data Access

Mercury NADP/MDN
Nitrogen & Sulfur Wet deposition NADP/NTN
Dry deposition CASTNet
Visibility IMPROVE

Abbreviations in the above table:

    CASTNet: EPA Clean Air Status and Trends Network
    GPMP: Gaseous Pollutant Monitoring Program
    IMPROVE: Interagency Monitoring of Protected Visual Environments
    MDN: Mercury Deposition Network
    NADP: National Atmospheric Deposition Program
    NPS: National Park Service
    NTN: National Trends Network
    VIEWS: Visibility Information Exchange Web System

For more information regarding monitoring and data assessments conducted by the National Park Service, link to the NPS Air Quality Monitoring Program or to the NPS Air Quality Monitoring History Database for a history of active and inactive monitoring sites at Everglades NP.

Key air quality related references from Everglades NP, Florida:

Barron, M. G., Duvall, S. E., Barron, K. J. 2004. Retrospective and Current Risks of Mercury to Panthers in the Florida Everglades. Ecotox. 13: 233–229.

Brandon, A., Cunningham, M., Onorato, D., Jansen D., Rumbold, D. G. 2009. Spatial and Temporal Patterns in Mercury Concentrations in Blood and Hair of Florida Panthers (Puma concolor coryi): 1978–2008. 30th Annual Meeting of Society of Environmental Toxicology and Chemistry, New Orleans, LA.

Carriger, J. F., Rand, G. M., Gardinali, P. R., Perry, W. B., Tompkins, M. S., Fernandez, A. M. 2006. Pesticides of Potential Ecological Concern in Sediment from South Florida Canals: An Ecological Risk Prioritization for Aquatic Arthropods. Soil and Sediment Contamination 15 (1): 21–45.

Carriger, J. F. and Rand, G. M. 2008a. Aquatic Risk Assessment of Pesticides in Surface Waters in and Adjacent to the Everglades and Biscayne National Parks: I. Hazard Assessment and Problem Formulation. Ecotoxicology 17 (7): 660–679.

Carriger, J. F. and Rand, G. M. 2008b. Aquatic Risk Assessment of Pesticides in Surface Waters in and Adjacent to the Everglades and Biscayne National Parks: II. Probabilistic Analyses. Ecotoxicology 17 (7): 680–696.

[EPA] U.S. Environmental Protection Agency. 2008. The National Listing of Fish Advisories. Available at

Florida [DOH] Department of Health. 2009. Your Guide To Eating Fish Caught In Florida. Available at (pdf, 918 KB).

Frederick, P. and Jayasena, N. 2010. Altered pairing behavior and reproductive success in white ibises exposed to environmentally relevant concentrations of methylmercury. Proceedings of the Royal Society B, doi: 10.1098/rspb.2010.2189.

Guentzel, J. L., Landing, W. M., Gill, G. A., Pollman, C. D. 1998. Mercury and major ions in rainfall, throughfall, and foliage from the Florida Everglades. The Science of the Total Environment 213: 43–51.

[IMPROVE] Interagency Monitoring of Protected Visual Environments. 2010. Improve Summary Data. Available at

Krabbenhoft, D. P. 2010. Mercury Bioaccumulation in Everglades Pythons. Poster, Greater Everglades Ecosystem Restoration Conference: July 12–16, 2010. Naples, FL.

Kohut, B. 2004. Assessing the Risk of Foliar Injury from Ozone on Vegetation in Parks in the South Florida / Caribbean Network. Available at (pdf, 130 KB).

Newman, J., Zillioux, E., Rich, E., Liang, L., Newman, C. 2004. Historical and Other Patterns of Monomethyl and Inorganic Mercury in the Florida Panther (Puma concolor coryi). Arch. Environ. Contam. Toxicol. 48: 75–80.

[NPS] National Park Service. 2010. Air Quality in National Parks: 2009 Annual Performance and Progress Report. Natural Resource Report NPS/NRPC/ARD/NRR—2010/266. National Park Service, Denver, Colorado. Available at Parks_2009_Final_Web.pdf (pdf, 2.8 MB).

Rand, G. M. and Carriger, J. F. 2004. Screening Level Ecological Risk Assessment (SERA): Canal-111 and Adjacent Coastal Areas. Report submitted to Everglades National Park.

Rand, G.M. et al. South Florida Freshwater Ecological Risk Assessment: 1990–2007. In Prep.

Roelke, M. E., Schultz, D. P., Facemire, C. F., Sundlof, S. F., Royals, H. E. 1991. Mercury Contamination in Florida Panthers. Report of the Florida Panther Technical Subcommittee to the Florida Panther Interagency Committee.

Rumbold, D. G. 2005. A probabilistic risk assessment of the effects of methylmercury on great egrets and bald eagles foraging at a constructed wetland in South Florida relative to the Everglades. Human and Ecological Risk Assessment 11 (2): 365–388.

Rumbold, D. G., Fink, L. E., Laine, K. A., Niemczyk, S. L., Chandrasekhar, T., Wankel, S. D., Kendall, C. 2002. Levels of mercury in alligators (Alligator mississippiensis) collected along a transect through the Florida Everglades. Science of the Total Environment 297 (1–3): 239–252.

[SFER] South Florida Environmental Report. 2011. Volume I The South Florida Environment. South Florida Water Management District, West Palm Beach, Florida. Available at
page/portal/pg_grp_sfwmd_sfer /portlet_prevreport/2011_sfer/v1/vol1_table_of_contents.html

Sullivan, T. J., T. C. McDonnell, G. T. McPherson, S. D. Mackey, and D. Moore. 2011. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/313. National Park Service, Denver, Colorado. Available at

Sullivan, T. J., T. C. McDonnell, G. T. McPherson, S. D. Mackey, and D. Moore. 2011b. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: South Florida/Caribbean Network (SFCN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/308. National Park Service, Denver, Colorado. Available at (pdf, 12 MB).

Sundlof, S. F., Spalding, M. G., Wentworth, J. D., Steible, C. K. 1994. Mercury in Livers of Wading Birds (Ciconiiformes) in Southern Florida. Archives of Environmental Contamination and Toxicology 27 (3): 299–305.

Ugarte, C. A., Rice, K. G., Donnelly, M. A. 2005. Variation of total mercury concentrations in pig frogs (Rana grylio) across the Florida Everglades, USA. Science of the Total Environment 345 (1–3): 51–59.

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Pollutants including mercury, nitrogen, ozone, and fine particles affect resources such as streams, soils, and scenic vistas. Find out how on our Everglades NP Air Pollution Impacts web page.

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Last Updated: January 03, 2017