South Florida

Meeting Florida's invasive species

From giant snakes to walking fish, a drive around South Florida reflects a global problem

As we move around the world we sometimes knowingly, and often unknowingly, bring other animals with us. Plants and animals hitch rides in our vehicles. Seeds, bacteria, and viruses hide in the soles of our shoes. We bring animals that would normally live on other continents into our homes as pets. The list of ways that we move biodiversity around the world today is seemingly endless. Occassionally some of these hitchhiking species leave our sides and enter the wild. When they do, the results can turn into an environmental disaster.

It is currently estimated that the introduction and establishment of non-native or ‘invasive species’ costs the US economy 120 Billion Dollars a year and directly accounts for 42% of wildlife declines in our country. These numbers are likely underestimated.
Invasive species effect our infrastruture, food supply, property values, and native diversity. Let’s look at some examples summarized from a statement from US Fish and Wildlife :

Every year invasive rats eat over $19 billion dollars of our stored grains while invasive insects destroy crops worth over $13 billion.

If invasive shellfish reach Washington State, their economic impact on the Columbia River alone would exceed $300 million not including cleanup or increased costs to other industries (e.g., salmon hatcheries) affected.

A single invasive plant caused such ecological damage to lakes in Vermont and Wisconsin that lakefront property values went down by an average of 15%, while the invasive pathogen that results in California’s oak death has led to $135 million in lost property values.

Invasive lionfish have lowered recruitment of fish along the Atlantic coast by as much as 79%. Lionfish are predicted to have a major negative impact on the Atlantic and Caribbean fishing industry, tourism, and reef conservation efforts over the next decade.

The list goes on and on. Invasive species are a global problem and in the US we can easily find invasive species right in our neighborhoods . However, in South Florida the numbers of invasive species that you can find are nothing short of unreal.

The Invasion of Florida


Over a quarter of the animals now found in Southern Florida are non-native. A full third of the plants found in Florica are non-native. This is one of the highest rates of species invasion in the world and costs the state over $500 million a year.

Following a conference hosted by the Bulletin of Marine Science in Miami this November, I had a chance to team up with a group of local reptile enthusiasts and see some of the region’s invasive species firsthand.

Perhaps the most famous invader of Florida is the burmese python Python bivittatus. Although these snakes are commonly kept as pets, there is a problem for people keeping these animals that has led to their repeated release into the wild:

They get big. Really big.

Unfortunately the continual release of snakes by petowners has wreaked havoc on the native species of Florida. By eating their way through the everglades these snakes are wiping out South Florida’s mammals. Common animals like foxes, rabbits, possums, and deer are either absent or severely declining in areas with pythons. These snakes are anything but rare and can reach lengths over 12 feet.

I observed several, the smallest one still easily over 7 feet long, crossing in front of our vehicles.

Pythons aren’t the only invaders we encountered. Glimpsing into the water to look at fish was like glimpsing into a fish tank at a pet store. Pleco catfish and African cichlids had replaced the fish you would have seen in the same waters a hundred years ago. During a rain, walking catfish strolled across the road next to treefrogs.

This short post doesn’t even begin to scratch the surface of the long list of exotics and their impact on Florida. But it is also indicative of a global problem facing us today. The way that biodiversity moves around our planet has changed. Although there are numerous examples of species from far away places colonizing an area naturally over evolutionary time (for example, our work on the rainforest trees of Madagascar), the rate and number of transitions is unprecedented.

Helmus et al. referred to this change in how organisms move around the planet as a “flatting” of species area relationships. Areas are no longer isolated by geography and distance. Area isolation is determined by how economically isolated the humans that live in them are.

This makes studying the impacts of invasion incredibly important for densely populated areas such as South Florida. While we can likely never remove all of these new colonists, we can mitigate their impact and protect areas that they have not yet spread too. We can also utilize a combination of ecological and climatic modelling in conjunction with a lineage or region’s evolutionary history to determine which new species are more likely to invade, which regions facilitate the fastest spread, and what additional factors could prevent a massive invasion.

Driving around South Florida and meeting its native and exotic animals truly underscores how important engaging in biodiversity research and management efforts is now if we want to be long-term stewards of our planet.

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