Everglades Pollution: Impacting Wildlife, What's The Damage?

The Everglades National Park is often referred to as the most threatened park in the U.S.. The park is affected by many sources of air pollution, including power plants, urban areas, agriculture, and industry. These pollutants can harm the park's natural resources, such as surface waters, vegetation, birds, and fish. One of the main issues with Everglades water quality is phosphorus enrichment, which has degraded water quality since the 1960s. Another issue is elevated mercury levels in wildlife, which can be toxic to both animals and humans. In addition, invasive species, rising sea levels, and climate change all pose significant threats to the Everglades and its wildlife.

Eutrophication and acidification

Eutrophication in the Everglades is primarily driven by agricultural runoff, which contributes high levels of phosphorus to the ecosystem. This has led to a shift in the natural nutrient-removal system, with the northern Everglades, historically acting as a sink, now becoming a nutrient source. Canals constructed for water management have also played a role in transporting polluted water into the Everglades, further exacerbating the issue. The excess phosphorus has led to phosphorus enrichment in the water, with levels exceeding the Phase I control target of 50 parts per billion in about 44% of the Everglades canal system and 4% of the marsh area as of 1995-1996. This has resulted in changes in vegetation, with cattail encroachment and a decrease in sawgrass marsh, which was previously the dominant plant community.

Agricultural releases of sulfate into the freshwater Everglades have also contributed to eutrophication and have been identified as a major concern due to their deleterious effects on the ecosystem. Sulfate enrichment has led to the biomagnification of toxic mercury in wildlife, increasing the risk of human exposure, and the formation of hydrogen sulfide, which is toxic to wetland vegetation and aquatic animals, particularly burrowing species.

Acidification, caused by nitrogen and sulfur deposition, has led to the leaching of important cations from soils, lakes, ponds, and streams, resulting in decreased habitat quality. While the sensitivity of the Everglades to acidification is relatively low compared to other national parks, it still poses a threat to certain plant and lichen species.

Overall, eutrophication and acidification have significant impacts on the wildlife of the Everglades, altering the natural balance of the ecosystem and threatening the survival of various plant and animal species.

Mercury contamination

The sources of mercury contamination in the Everglades are diverse. Firstly, agricultural practices, such as fertilizer applications and pesticide use, release mercury into the ecosystem. Additionally, nearby power plants, urban areas, and industrial activities contribute to mercury pollution in the region. Atmospheric deposition plays a significant role, as mercury can travel long distances through the air before settling on water surfaces, undergoing methylation, and eventually finding its way into the food chain.

The effects of mercury contamination on Everglades wildlife are profound and wide-ranging. It has been linked to reduced reproductive success and impaired growth and development in various species. For example, research has shown that mercury exposure decreases the propensity of great egrets to initiate breeding, with a reduction of over 50% in the Florida Everglades. Mercury contamination also affects the behaviour of birds, with egret nestlings exhibiting disoriented behaviour and males forming male-male pairs.

Mercury bioaccumulation has been observed in several species, including largemouth bass, alligators, and pythons. In fact, python mercury levels have been found to be three to four times higher than in alligators, which were previously considered the highest in the ecosystem. This has raised concerns about the survival of pythons in the region. Additionally, mercury levels in largemouth bass in the Everglades remain high, prompting the Florida Department of Health to issue "Do Not Eat" advisories for women of childbearing age and young children.

The endangered Florida panther, a unique species to the Everglades, has also been impacted by mercury contamination. Studies have shown high levels of mercury in their hair and blood, which may be related to their diet, including fish-eating wildlife. This contamination puts an already vulnerable species at further risk.

Recent years have seen a decrease in mercury contamination in the Everglades, which has had positive effects on bird populations. However, the issue of mercury contamination in the Everglades remains a critical concern, requiring ongoing efforts to protect and restore the health of this unique ecosystem and its diverse wildlife.

Climate change

The Everglades, already sensitive to water flow changes, faces increased risks of saltwater intrusion as sea levels continue to rise. This intrusion can harm drinking water aquifers and freshwater vegetation and compromise the habitats of numerous species. The warming climate is also leading to increased precipitation and more intense hurricane seasons, which have damaged coral reefs and shuttered visitor centers.

The interconnectedness of air quality and climate change is evident in the Everglades. Industrial air pollution from nearby sources, such as power plants and agricultural practices, contributes to both local air quality issues and the broader climate crisis. Sugarcane burning, a practice unique to Florida's agricultural industry, exacerbates air pollution across the state, including in the Everglades.

The impacts of rising sea levels and changing salinity on wildlife in and around the Everglades remain uncertain. However, the projected loss of habitat and marsh nurseries could harm many species. Researchers predict that the endangered Cape Sable seaside sparrow, a ground-nesting bird, will significantly decline in population as sea levels continue to rise.

To address these challenges, efforts are being made to update industrial facilities to reduce pollution, monitor air quality in nearby communities, and emphasize the importance of stronger climate science and adaptation measures.

Introduced species

The Everglades is a massive watershed in the southern portion of the US state of Florida. It is a subtropical wetland ecosystem spanning two million acres across central and south Florida. The Everglades is internationally known for its extraordinary wildlife. The region hosts one of the highest numbers of exotic plant species in the world.

The Everglades is being threatened by numerous plants and animals that were introduced both on purpose and by accident. Some introduced species become a small part of the landscape, while others thrive at the expense of native plants and wildlife. When an introduced species puts additional stresses on native wildlife and threatens habitats, it is called an invasive species.

Due to the alteration of water flows and the interruption in the natural pattern of wildfires, invasive species are a significant threat in the Everglades. These species from other parts of the world are taking advantage of the unbalanced conditions to establish themselves, whereas native plants and animals are struggling to survive. An invasive species is able to spread throughout new ecosystems because it doesn't have the natural predators from its native land to keep it in check. Once they've become established, these invaders are hard to stop.

About 1.7 million acres of the Everglades have been invaded by non-native plants, such as the Brazilian peppertree, Chinese privet, the broad-leaved paperbark tree or "melaleuca", and Old World climbing fern. Another harmful invasive species is the Burmese python, which likely escaped into the park when hurricanes destroyed the captive breeding facilities used to furnish pet owners. These snakes have nearly wiped out most small mammals in the park and have even been known to prey on alligators. Other animal invaders that prey on, or compete with, native species include Cuban tree frogs, which eat smaller native frogs, and Nile monitors, which eat burrowing owls and crocodile eggs.

In addition to the Burmese python and Nile monitors, other invasive reptiles in the Everglades include the green anaconda, the spectacled caiman, the tokay gecko, and the knight anole. Invasive mammals include wild boars, feral pigs, feral cats, black rats, and wild dogs.

Invasive birds in the Everglades include the monk parakeet, the Muscovy duck, and the iguanas.

Invasive fish species include the Mayan cichlid, the blue tilapia, the sailfin catfish, the suckermouth catfish, the walking catfish, and the pike killifish.

Invasive amphibians include the island apple snail, the Asiatic clam, and the bromeliad beetle.

Invasive plants include the water hyacinth, the water lettuce, the Burma reed, the hydrilla, the air potato, the carrotwood, the downy rose myrtle, and the Australian pine.

Agricultural chemicals

The natural plant and animal communities in the Everglades developed under very low phosphorus conditions, so high levels of phosphorus cause significant issues. These include the loss of native plant communities and open water areas where wading birds feed, and a reduction in the dissolved oxygen in the water, which fish need to survive. By 1990, it was estimated that over 40,000 acres of the public Everglades had been impacted by phosphorus pollution.

Other chemicals released through agricultural practices have also contributed to pollution. Sulfate released into the freshwater Everglades by agriculture has caused two main issues: the biomagnification of toxic mercury in wildlife, and the formation of hydrogen sulfide in Everglades soils, which is toxic to wetland vegetation and aquatic animals, particularly burrowing species.

Agricultural sources of pollution also contribute to the deposition of nitrogen compounds, which disrupt the delicate balance of the Everglades' aquatic ecosystems.

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