Florida's Everglades Dirty Dozen
Under the Microscope
Updated on: January 2024
Nestled at the southern tip of Florida, the Everglades is a vast, subtropical wilderness that stretches over 1.5 million acres. Often referred to as the ‘River of Grass,’ this unique ecosystem is a mosaic of freshwater ponds, prairies, and swamps, supporting an unparalleled diversity of flora and fauna. Among its rich tapestry of life, however, lurks a less welcome presence: the “Dirty Dozen.” This group comprises twelve invasive species that, over time, have found their way into the Everglades and now pose significant threats to its ecological balance. From the notorious Burmese python, which preys on native mammals and birds, to the Old World climbing fern, which smothers native vegetation, these invaders not only disrupt habitats but also alter the very fabric of this fragile environment.
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What Are the Everglades Invasive Species?
Florida’s Everglades is under siege by an infamous group of invasive species known as the “Dirty Dozen.” This unwelcome assembly includes the Burmese Python, known for its massive size and appetite; the Brazilian Pepper Plant, which smothers native flora; the voracious Lionfish; the rapidly multiplying Air Potato; the habitat-altering Australian Pine; the elusive Nile Monitor; the prolific Old World Climbing Fern; the large and disruptive Bullseye Snakehead; the aggressive Cuban Treefrog; the prolific Giant African Land Snail; the water-structuring Melaleuca tree; and the encroaching Chameleons. Each of these species contributes to the degradation of the Everglades’ delicate ecosystem, threatening its biodiversity and ecological balance. This introduction sets the stage for a deeper exploration into how each species arrived, their specific impacts, and the ongoing efforts to mitigate their presence in this unique and vital environment.
Key Takeaway
The unchecked spread of the “Dirty Dozen” invasive species threatens the Everglades’ unique biodiversity, with some initiatives, like the Lionfish Removal and Awareness Day, successfully removing thousands of invasive species from Florida waters annually.
Burmese Python
Burmese pythons are one of the most concerning invasive species in the Florida Everglades. Originally from Southeast Asia, these massive constrictor snakes can grow up to 23 feet in length and weigh over 200 pounds, although the average is typically around 12 feet. They possess beautifully patterned skin, varying from tan to yellow with dark brown blotches, aiding them in camouflage within the dense, marshy terrain of the Everglades.
The Everglades, a vast network of wetlands and forests, is an ideal habitat for these pythons due to its warm climate, abundant water, and plentiful prey. They are typically found in marshes, hammocks, and other wet environments where they can remain concealed and close to water sources. The pythons were likely introduced into this ecosystem as released or escaped pets from the exotic pet trade.
The impact of Burmese pythons in the Everglades is profound and detrimental. As top-level predators with no natural enemies in this environment, they significantly disrupt the natural balance. They prey on a wide variety of species, including endangered and threatened animals. Their voracious appetite and ability to consume large prey allow them to outcompete native predators, leading to a decline in the populations of native mammals, birds, and even alligators. This affects not only the biodiversity but also the overall health of the Everglades ecosystem.
Efforts to control the python population include public hunting programs, tracking and removal by wildlife professionals, and research into more effective eradication methods. Despite these efforts, the Burmese python remains a resilient and elusive challenge, underlining the need for continued and enhanced conservation strategies to protect the unique and precious ecosystem of the Florida Everglades.
Black and White Tegu
The Black and White Tegu is another invasive species causing concern in the Florida Everglades. Originating from South America, particularly Brazil, Paraguay, Uruguay, and Argentina, these large lizards can grow up to 4 feet in length. They are known for their distinctive black and white coloration, with banding across their bodies and tails, which helps them blend into their surroundings.
Tegus are adaptable creatures and can thrive in a variety of environments, but they are often found in the Everglades’ forested areas, grasslands, and even residential regions. Their ability to tolerate different habitats makes them particularly invasive. They were likely introduced into the Everglades through the exotic pet trade, either by escape or intentional release by owners who could no longer care for them.
The impact of Black and White Tegus in the Everglades is significant. They are omnivorous and consume a wide range of food, including fruit, vegetables, eggs, insects, and small animals. This diet means they compete with native species for food and can also directly reduce populations of certain animals by preying on them, including ground-nesting birds and reptiles like the American alligator and the American crocodile, both of which are iconic species of the Everglades.
Additionally, Tegus might pose a threat to the eggs of various native species, including endangered ones. Their habit of digging and burrowing can also lead to physical alterations to the landscape, affecting the natural habitat of other species. The introduction and spread of Tegus have prompted concerns about the potential long-term ecological impacts and the displacement of native species.
Attempts to control the Black and White Tegu population in the Everglades include trapping, public awareness campaigns, and research into their behavior and ecology to develop more effective management strategies. Florida has also implemented laws and regulations to manage the trade and ownership of Tegus to prevent further introductions. Despite these efforts, the Black and White Tegu remains a persistent and adaptable invader, challenging the ecological balance of the Florida Everglades and highlighting the need for ongoing and dedicated conservation efforts.
Cuban Treefrog
Cuban Treefrogs are another invasive species in the Florida Everglades that have drawn concern from ecologists and conservationists. Originating from Cuba, the Bahamas, and the Cayman Islands, these amphibians have successfully established themselves in the Everglades and other parts of Florida. They are the largest treefrog species in North America, reaching up to 5 inches in length. Cuban Treefrogs are usually gray, brown, or green, and can change color depending on their environment. They have smooth skin, large toe pads for climbing, and prominent eyes.
These frogs are often found in both natural and human-made environments, demonstrating a high degree of adaptability. In the Everglades, they typically inhabit trees and shrubs near water sources but are also commonly found around buildings, in gardens, and other residential areas where they can find food and shelter.
The impact of Cuban Treefrogs on the Everglades ecosystem is multifaceted and concerning. They are voracious eaters and consume a wide variety of invertebrates, as well as smaller frogs, thus competing with native species for food. Their presence has been linked to declines in native frog populations, as they not only outcompete them for resources but also prey directly on them. Secondly, Cuban Treefrogs can disrupt the natural food web, impacting species that rely on native frogs for their diet.
Moreover, these frogs can secrete a toxic mucus that can deter predators and irritate human skin, posing a risk to native wildlife and pets. Their breeding habits also exacerbate their impact; they reproduce quickly and in large numbers, which allows their populations to grow rapidly and makes them difficult to control.
Giant African Land Snail
The Giant African Land Snail (GALS), specifically the species Achatina fulica, is a highly invasive and destructive species found in the Florida Everglades and other parts of Florida. Originally from East Africa, these snails have become one of the most problematic invasive species in the region due to their size, reproductive rate, and eating habits.
Giant African Land Snails can grow up to 8 inches in length and 4 inches in diameter, making them one of the largest snail species in the world. They have a conical shell with a brownish or yellowish color and distinct dark brown stripes. Their size and the coiling pattern of their shells are distinctive features that help in their identification.
In Florida, these snails are commonly found in a variety of habitats, including gardens, farms, and urban areas, as well as in the natural environments of the Everglades. They prefer moist, warm conditions and are often found in soil, under vegetation, or within debris where they can find food and shelter.
Controlling the population of Giant African Land Snails is challenging due to their rapid reproduction rate and the fact that they have few natural predators in Florida. Efforts to manage their numbers include public education, rigorous inspection and quarantine measures to prevent further spread, the use of bait and chemical treatments to reduce populations, and research into more effective control methods. The Florida Department of Agriculture and Consumer Services has been particularly active in efforts to eradicate these snails, conducting regular surveys and response activities. Despite these efforts, the Giant African Land Snail remains a significant invasive species in the Florida Everglades, representing a continuous threat to agriculture, natural ecosystems, and human health.
Australian Pine
The Australian Pine, also known as Casuarina spp, is a highly invasive tree species in the Florida Everglades and other coastal areas of Florida. Despite its common name, it’s not a true pine but rather belongs to a genus of flowering plants. It was originally introduced to Florida in the late 19th and early 20th centuries for purposes such as windbreaks, erosion control, and timber.
Australian Pines can grow up to 100 feet tall, with long, slender, drooping branches that resemble pine needles. These “needles” are actually modified twigs that perform photosynthesis. The trees produce small, cone-like structures and have distinctive, rough, and segmented bark.
In the Everglades and surrounding areas, Australian Pines are commonly found along coastlines, riverbanks, and other disturbed areas where they can outcompete native vegetation. They prefer sandy soils and are tolerant of salt and wind, making them well-suited to Florida’s coastal environments.
Restoration projects often involve replanting native vegetation to help recover the natural ecosystem of Australian Pines. However, due to their widespread presence and rapid growth, completely eradicating Australian Pines is challenging, and ongoing management is required to mitigate their impact on the Florida Everglades and other affected areas.
Old World Climbing Fern
The Old World Climbing Fern, known scientifically as Lygodium microphyllum, is a highly invasive fern species causing significant ecological concerns in the Florida Everglades. Originating from Africa, Asia, and Australia, this fern was introduced to Florida in the 1960s and has since spread aggressively throughout the Everglades and other natural areas.
The Old World Climbing Fern is a climbing vine-like fern that can grow indefinitely, with individual fronds reaching up to 90 feet long in some cases. The fern has delicate, small leaves (microphylls) that are arranged in a feather-like pattern on twining stems. It produces spores on the underside of its leaves, which are easily dispersed by wind, aiding its rapid spread.
This fern is commonly found throughout the wetlands, hammocks, and tree islands of the Everglades. It thrives in moist environments but can also grow in drier areas. Its climbing nature allows it to ascend trees and shrubs, covering entire areas with a dense mat of vegetation.
Management efforts include mechanical removal, the application of herbicides, and the use of biological control agents that feed on the fern’s spores. However, the fern’s rapid growth and prolific spore production make control and eradication difficult. Ongoing research aims to find more effective ways to manage and control this invasive species to protect the Florida Everglades and other affected ecosystems. Despite these efforts, the Old World Climbing Fern remains a significant and challenging invasive species in the region.
Chameleons
Several species of chameleons have been introduced into the Florida Everglades, with the Veiled Chameleon (Chamaeleo calyptratus) and the Oustalet’s Chameleon (Furcifer oustaleti) being among the most notable. These reptiles are native to different parts of the world—Veiled Chameleons from the Arabian Peninsula and Oustalet’s Chameleons from Madagascar—but have found their way into Florida through the exotic pet trade. Escapes and intentional releases have led to their establishment in the wild.
Description
Veiled Chameleons – They can grow up to 24 inches long, with males being larger and more colorful than females. They are known for their striking appearance, including a distinctive casque (helmet-like structure) on their heads that grows taller as they mature. Their coloration varies, but they can display a mix of greens, yellows, and browns, changing shades to communicate or respond to temperature and emotions.
Oustalet’s Chameleons -These are among the largest chameleon species, with some individuals reaching up to 27 inches. They tend to be a brown or grayish color but can change shades. They have a less prominent casque than the Veiled Chameleon but still have the characteristic independently mobile eyes and long, sticky tongue.
Where to Find Them
Chameleons in Florida are typically found in warm, humid environments that mimic their native habitats. In the Everglades, they may be found in tree canopies, shrubbery, and near water sources. They prefer areas where they can blend into the foliage and have access to a steady supply of insects.
Impacts of Chameleons
Chameleons primarily feed on insects and have been known to eat large quantities. This can impact native insect populations and disrupt the local food web. They might also compete with native predators for food. Non-native chameleons could potentially introduce new diseases to native reptile and amphibian populations, which might not have resistance to these illnesses. If different species of chameleons interbreed, they could produce hybrid offspring, potentially impacting the genetics of native species. Native species might not recognize chameleons as predators or competitors, which could alter natural behaviors and survival strategies.
Controlling and managing the population of non-native chameleons is challenging due to their elusive nature and reproductive habits. Efforts typically include public education, promoting responsible pet ownership, and removal where possible. The impact of chameleons in the Everglades is still being studied, but like other invasive species, they have the potential to significantly alter the ecosystem. Understanding and mitigating these impacts is crucial to preserving the delicate balance of the Everglades’ unique environment.
Bullseye Snakehead
The Bullseye Snakehead (Channa marulius) is a species of snakehead fish that has become established in the Florida Everglades. Native to South and Southeast Asia, this invasive species was likely introduced into Florida waters through the release of unwanted aquarium pets or as a result of the exotic food trade. The presence of Bullseye Snakehead in the Everglades has raised concerns due to its potential impacts on the ecosystem.
Bullseye Snakeheads are large, predatory fish that can reach up to 47 inches in length, though most are smaller. They have a long, serpentine body shape with a flattened head and large mouth equipped with sharp teeth. Their coloration is generally dark brown with a mottled pattern, helping them blend into the murky waters of their habitat. A distinctive feature is the “bullseye” pattern near the base of the tail fin—a dark spot surrounded by a lighter ring.
Bullseye Snakeheads are primarily found in freshwater systems, including canals, rivers, lakes, and ponds. In the Florida Everglades, they are often seen in slow-moving or stagnant waters where they can hide among vegetation. They are well-adapted to low-oxygen environments and can breathe air, allowing them to survive in waters that might be inhospitable to other fish.
As top-level predators, these fish consume a wide array of prey, including fish, amphibians, and invertebrates. This predation can lead to a marked reduction in native species populations, disrupting the delicate balance of the aquatic food web. Additionally, Bullseye Snakeheads compete with native predators for both food and habitat. This competition can potentially displace native species, thereby altering the community structure. Their feeding habits further contribute to ecosystem alteration, leading to shifts in the types and numbers of species present. Such changes can have cascading effects, impacting water quality, vegetation, and the overall health of the aquatic environment. Moreover, Bullseye Snakeheads are known for their resilience and ability to spread to new areas. Their unique air-breathing capability allows them to survive in conditions that would be lethal to many other fish species. Coupled with the ability to move overland for short distances, they can potentially colonize new water bodies, further expanding their impact and posing a continuous threat to native ecosystems.
Brazilian Pepper Plant
The Brazilian Pepper Plant, known scientifically as Schinus terebinthifolius, is one of the most invasive and troublesome plant species in the Florida Everglades. This species, native to Argentina, Paraguay, and Brazil, was introduced to Florida in the mid-1800s for ornamental purposes. Its attractive red berries and lush foliage made it popular in landscaping, but these same characteristics have allowed it to spread aggressively in natural areas like the Everglades.
The Brazilian Pepper Plant is a dense, evergreen shrub or small tree that can grow up to 30 feet tall. Its compound leaves are dark green, glossy, and have a distinctive aroma when crushed. The plant produces small white flowers that develop into clusters of bright red berries, which are a key factor in its spread. The berries are attractive to birds and other wildlife, which eat them and disperse the seeds over wide areas.
In the Florida Everglades, Brazilian Pepper Plants are commonly found in disturbed areas, along roadsides, in wetlands, and on tree islands. They thrive in both dry and wet conditions and can quickly dominate an area, forming dense thickets that are difficult to remove. These plants prefer sunny locations but can also grow in partially shaded environments.
The pervasive nature of the Brazilian Pepper Plant makes it particularly challenging to eradicate, often hindering restoration efforts and necessitating substantial resources for its control and removal. Moreover, the seeds left in the soil can lead to quick re-infestation even after initial removal. Besides its environmental impacts, the plant is known to cause respiratory and skin reactions in some individuals, adding a public health concern to its invasive nature.
Air Potato
The Air Potato (Dioscorea bulbifera) is a particularly aggressive and problematic invasive plant species found in the Florida Everglades and other parts of Florida. Native to Africa, Asia, and Australia, this vine was introduced to the Americas as an ornamental plant and for potential food use, given its tuberous nature. However, it has since become an ecological nuisance in many natural areas, including the Everglades.
The Air Potato is a perennial vine that can grow extremely quickly, sometimes up to 8 inches per day, reaching heights of more than 70 feet. It has broad, heart-shaped leaves and produces aerial tubers, known as “bulbils,” which resemble small potatoes hanging from the vine. These bulbils are the primary means of reproduction, though the plant also produces underground tubers. When they fall to the ground, each bulbil can give rise to a new plant, leading to rapid and widespread proliferation.
In the Florida Everglades, Air Potato vines are often found climbing over trees, shrubs, and other vegetation, forming dense mats that can cover large areas. They prefer disturbed areas, edges of forests, and open canopy areas where sunlight is abundant. However, they can also be found in more shaded environments, demonstrating a high degree of adaptability.
The Air Potato aggressively smothers native vegetation in the Florida Everglades, leading to a significant decline in biodiversity and habitat alteration. Its prolific reproduction through aerial bulbils makes control efforts, including physical removal and biological agents, challenging. Despite ongoing management strategies, the Air Potato remains a persistent and destructive invasive species in this unique ecosystem.
Lionfish
Lionfish, specifically the Red Lionfish and the Devil Lionfish (, are invasive species causing significant concern in the Florida Everglades and the broader Atlantic Ocean and Gulf of Mexico. Originally from the Indo-Pacific region, these lionfish were likely introduced into Florida waters through the aquarium trade, with individuals being released into the wild.
Lionfish are known for their striking appearance. They have elongated, fan-like fins and bold, zebra-like stripes of red, white, and brown, which serve as a warning to potential predators of their venomous spines. These fish can grow up to 18 inches long, though most are smaller. They have a row of long, venomous dorsal spines, as well as smaller spines on their pelvic and anal fins, which they use for defense.
While lionfish are not typically found in the freshwater environments of the Everglades themselves, they are prevalent in the nearby marine and estuarine waters, including coral reefs, mangroves, seagrass beds, and artificial structures like shipwrecks and piers. Their adaptability to various marine environments and lack of natural predators in the Atlantic allow them to occupy a wide range of depths and habitats.
Lionfish have significantly impacted the marine ecosystems around the Florida Everglades, primarily through their voracious predation habits, which involve consuming over 70 different species of fish and invertebrates. This predatory behavior leads to considerable declines in native fish populations and disrupts the ecological balance, further exacerbated by their competition with native predators for food and habitat. Compounding these issues is the lionfish’s rapid reproductive rate, with females releasing thousands of eggs every few days, leading to swift population growth and spread. Despite efforts like organized culls and public awareness campaigns, lionfish continue to be a formidable and damaging invasive species in the waters surrounding the Florida Everglades.
Nile Monitor
The Nile Monitor, a robust and invasive reptile from Africa, has established a concerning presence in the Florida Everglades. These large lizards, which can grow up to an imposing 7 feet in length, are easily identified by their muscular build, powerful limbs equipped with strong claws, and a striking pattern of light yellow to olive green bands and spots over their dark skin. Adapted for a semi-aquatic lifestyle, Nile Monitors are exceptional swimmers, a trait that makes the water-rich environments of the Everglades an ideal habitat for them. They are most commonly observed near rivers, canals, marshes, and other water bodies, where they have easy access to food and shelter.
The impact of the Nile Monitor on the Everglades ecosystem is multifaceted and deeply concerning. As carnivores, they have a varied diet that includes fish, frogs, small mammals, and birds, as well as the eggs of native reptiles like alligators and turtles. This diverse appetite means they compete directly with native predators for food, potentially leading to a reduction in these species and an imbalance in the food web. The consumption of eggs of native species is particularly damaging, as it can lead to a decrease in the populations of already vulnerable species and further disrupt the ecological balance.
Controlling the population of Nile Monitors in the Everglades is a significant challenge. Their elusive nature makes them difficult to capture, and they reproduce rapidly, with females laying dozens of eggs at a time, which can hatch into a new generation of monitors capable of further expanding their territory. Efforts to manage their numbers include trapping and removal programs, public education to prevent the release of exotic pets, and research to better understand their behavior and impact on the ecosystem. Despite these efforts, the Nile Monitor continues to be a persistent and problematic invasive species in the Florida Everglades, necessitating ongoing attention and resources to protect this unique and vital ecosystem.
Conclusion
The “Dirty Dozen” of Florida’s Everglades represents a significant and pressing ecological challenge, underscoring the complex and often unintended consequences of species introduction into non-native environments. From the vast appetite of the Burmese Python to the suffocating tendrils of the Old World Climbing Fern, each species poses its own unique threat to the biodiversity and structural integrity of this unique ecosystem. Efforts to manage and mitigate these invaders are ongoing and require a combination of public awareness, scientific research, and innovative management strategies. The plight of the Everglades serves as a poignant reminder of the delicate balance of natural ecosystems and the importance of vigilant stewardship to preserve these treasures for future generations. The fight against the “Dirty Dozen” is not just about saving a regional treasure; it’s about maintaining the ecological diversity and health of our planet.
