The Everglades, a vast wetland ecosystem in South Florida, stands as a unique and biodiverse natural treasure. This intricate network of marshes, swamps, and forests supports an array of native plant and animal life. However, this delicate balance faces a significant and ongoing challenge from the proliferation of invasive species.
Understanding the Scale of Invasion
The Everglades hosts over 250 established invasive species, including plants, amphibians, fish, birds, reptiles, mammals, and invertebrates. Florida faces one of the nation’s most severe non-native species problems, with approximately 1,000 of its 4,000 plant species being non-native.
Counting an exact number is challenging due to ongoing introductions and detection difficulties. An invasive species is defined as a non-native species introduced by humans that causes environmental, economic, or health harm.
Recent decades show an increase in exotic species within the Everglades. This proliferation stems from South Florida’s role as a transportation hub, facilitating introductions through agriculture, shipping, and the pet trade. Approximately 26% of South Florida’s fish, reptiles, birds, and mammals are now exotic.
Prominent Invasive Species
Several species have significantly impacted the Everglades. The Burmese python, native to Southeast Asia, established populations from escaped pets, with numbers increasing after Hurricane Andrew in 1992. These large constrictor snakes, which can grow over 20 feet long, are apex predators, preying on native mammals, birds, and alligators. They have established breeding populations across Miami-Dade, Monroe, and Collier counties, and are spreading north within Florida.
Lionfish, from the Indian and Pacific Oceans, were introduced to Florida waters through aquarium releases. These fish possess venomous spines and can consume over 70 different species of fish and invertebrates. They have spread throughout the Caribbean, Atlantic, and Gulf of Mexico, including Florida Bay, threatening marine ecosystems.
The Tegu lizard, from South America, established populations from escaped pets. These large, omnivorous lizards, some reaching four feet in length, consume fruits, insects, small animals, and especially eggs, including those of native alligators and turtles. Breeding populations are centered in Miami-Dade and Hillsborough counties and are expanding into Everglades National Park and other areas.
Among invasive plants, the Melaleuca tree, native to Australia, was introduced to Florida in 1906 for timber and land drying. This fast-growing tree forms dense stands, displacing native cypress and sawgrass and disrupting water flows. It infests over 400,000 acres in South Florida, and its oil-rich leaves create a fire hazard.
Brazilian Pepper, from South America, was imported as an ornamental species in the late 1800s. This shrub forms dense canopies that shade out native vegetation and produce chemicals inhibiting other plant growth. It is the most widespread non-native invasive plant in Florida, occupying over 700,000 acres and invading natural communities, including Everglades National Park.
Impact on the Everglades Ecosystem
Invasive species alter the Everglades ecosystem, threatening native flora and fauna. These organisms outcompete indigenous species for resources like sunlight, water, and nutrients. Invasive plants like melaleuca and Brazilian pepper create dense monocultures, displacing native vegetation essential for biodiversity.
Predation by invasive animals causes declines in native wildlife. Burmese pythons, for instance, have caused mammal populations, including raccoons, opossums, and bobcats, to plummet by up to 99% in areas they inhabit. Tegu lizards consume eggs of native reptiles and ground-nesting birds, impacting reproductive success. Lionfish prey on native fish and invertebrates, disrupting the marine food web.
Invasive species also alter physical habitats. Melaleuca trees can dry out wetlands and disrupt water flow, and their flammable leaves increase wildfire risk. Brazilian pepper forms thickets that change habitat structure, making them unsuitable for native species. These alterations impact the food web and ecosystem functions.
Strategies for Control and Prevention
Controlling invasive species in the Everglades involves control measures and prevention strategies. Early detection and rapid response systems identify new populations and initiate control before widespread establishment. Public participation through platforms like “IveGot1” helps authorities locate and respond to sightings.
Physical removal programs manage existing invasive populations. For Burmese pythons, efforts include the Python Elimination Program, which employs paid contractors, and the annual Florida Python Challenge. Biologists use techniques like radio telemetry with “scout snakes” to locate and remove breeding pythons, focusing on adult females. Invasive plants like melaleuca and Brazilian pepper are managed through manual removal and herbicide applications.
Biological control methods offer a long-term strategy for widespread plant invaders. For example, insects that are natural enemies of melaleuca have been released in the Everglades to reduce the tree’s growth. These agents weaken invasive species, making them less competitive against native plants.
Preventing new introductions is a key aspect of invasive species management. Public awareness campaigns, like “Don’t Let It Loose,” educate pet owners about releasing exotic animals. Florida has also implemented stricter regulations on the pet trade, banning possession and breeding of high-risk invasive reptiles like Burmese pythons, tegus, and green iguanas, and requiring permits for existing pets. These strategies, often involving collaborations, aim to mitigate the threat posed by invasive species to the Everglades.