Imagine someone coming into your home, eating all your food, destroying your furniture, and then refusing to leave. Talk about an unwelcomed house guest, but it's actually a very accurate comparison of what can happen when an invasive species moves into an environment. Whether it's a plant, animal, or other organism (such as a microbe), when a non-native element is introduced into an ecosystem that's not prepared to handle such things, the impact is usually devastating, both in terms of wiping out habitats and generating significant financial losses as well. According to a recent report in "The Washington Post," invasive species are responsible for $120 billion in collateral damage each year, and sadly, most of these invasive species end up in the wrong place at the wrong time because of human action.
Let's take a look at some of the areas that have suffered the most as a result of invasive species, including the culprit behind the destruction, how it first entered the ecosystem, the damage done, and any steps taken (past or present) to get things back under control.
10: Lionfish Zero in on Caribbean Coral Reefs
The crystal blue waters of the Caribbean may seem calming from the surface, but there's been a disturbance lurking underneath since the mid-1990s, when lionfish first made their way from their native Indo-Pacific waters into this new, foreign habitat. Thought to have come by way of hurricanes as well as from aquariums dumped into the sea, lionfish have voracious appetites, with a diet that includes over 40 different types of fish and crustaceans [source: National Oceanic and Atmospheric Administration]. This wouldn't be such a problem except for the fact that lionfish have very few predators in the Caribbean. Those who do go after them, find themselves faced with a bit of challenge in nabbing their prey, as lionfish are also equipped with protective, external, venomous spines [source: NOAA].
Researchers from Oregon State University in conjunction with the National Oceanic Atmospheric Administration (NOAA) have since been studying the impact of lionfish in these tropical waters, and the results are staggering, with native coral reef fish populations declining as much as 80 percent. Though complete eradication of lionfish from Caribbean waters seems unlikely, efforts to control their devastating impact are currently in play. This includes creating targeted fisheries (lionfish tastes good and though it has venomous spines, cooking the fish negates any adverse impact) and reintroducing healthy populations of potential lionfish predators into the ecosystem, such as shark and grouper [source:NOAA].
9: Florida Fruit Orchards Pilfered by Monk Parakeets
Under normal circumstances, these birds call South America home, but they ended up taking a permanent vacation to Florida starting in the late 1960s when they were brought into the U.S. as exotic pets, before more stringent importing regulations regarding pet trade were put in place. Unfortunately for Floridians, these squawky birds are far too fond of flowering, nectar, and fruit-producing plants, and as a result, the state's ecosystem has suffered on numerous fronts. Fruit orchards are a favorite target of attack, and monk parakeets have the bad habit of spreading seeds from more exotic plants that can thrive in their original region but run the risk of becoming a nuisance if brought to a foreign area. The birds also form rather noisy flocks and tend to nest on light poles and electrical structures, which are often damaged as a result [source: University of Florida Dept. of Wildlife and Conservation].
Since monk parakeets source most of their food from bird feeders, residents in the Florida area can help curb the population by limiting this as an option. Additionally, several electric utility companies in Florida are conducting ongoing research to develop new trapping methods and other deterrents to help minimize costly damages created by their nests [source: University of Florida Dept. of Wildlife and Conservation].
8: Starlings Take States by Storm, Via Central Park
During the past 100 years, the European starling has damaged ecosystems in nearly every U.S. state with the exception of North Dakota and Alaska where they have yet to be pinpointed. Sporting purple and green iridescent plumages, the birds were first brought into New York's Central Park in the late 1800s by Eugene Schieffelin, a drug manufacturer who wanted to bring every bird referenced in Shakespeare's work to North America. The plan quickly backfired, as starlings are known for roosting in hoards reaching tens of thousands. Their droppings, which can accumulate 12 inches (0.3 meters) or deeper, are also cited as the trigger behind numerous infectious diseases harmful to plant life, other animals and humans, such as the transmissible gastroenteritis virus (TGE) [source: AgNIC Wildlife Damage Management].
Multiple approaches have been made to curb their population, including the use of poisoned pellets, Roman candles, even itching powder, but with little impact [source: Webley]. Current efforts include the encouragement of better farm management practices to limit the amount of livestock feed available for starlings to feast on, though they also enjoy fruit and insects [source: AgNIC Wildlife Damage Management].
6: Mountain Pine Beetles Barking Up Too Many Trees in Western U.S.
Wildfires have long plagued forests in the western half of the United States, but these trees face a much bigger threat that's far less visible but even more deadly: mountain pine beetles. For example, in 2007 these little buggers knocked out a staggering 3.9 million acres (1.6 million hectares) of trees across the states of Colorado, Montana, Wyoming, Idaho, Washington, Oregon and Utah. On average, fires burn down 3.4 million acres (1.38 million hectares) each year [source: Puckett].
Mountain pine beetles spend most of their lives underneath tree bark, where they bore and lay new eggs, subsequently severing the tree's circulation. Efforts to control their spread include dispersing chemicals similar to the ones they produce, thereby tricking them into thinking the tree is already playing egg host to other beetles. This procedure can prove costly, though [source: Puckett].
4: Southern States Covered in Kudzu
Though this vine was originally used in Asia for decorative and medicinal purposes, it made its stateside debut in 1876 in tandem with the Centennial Exposition in Philadelphia. By the 1930s, the U.S. government incentivized farmers to use it for erosion control. However, once the vine was introduced into the warmer climates of the South, its growing power proved to be a force to be reckoned with, as it began to grow a foot (30 centimeters) on average daily [source: Friedman].
With no known natural predators outside its native Asia, kudzu now covers over 7 million acres (2.8 million hectares) in the southern U.S., and has been responsible for killing trees, breaking power lines, and even collapsing buildings [source: Friedman]. As such, it has earned several not-so-nice nicknames, including "the vine that ate the South." Several control mechanisms have been investigated, including chemical solutions and biological means like the introduction of the Asian soybean rust, which has proved to be effective in eradicating the vine. Other efforts include finding useful ways to repurpose kudzu, such as in construction of baskets [source: Shores].
2: Cajun County Wrestles with Nutria
Also known as the "Swamp Beaver" and originally found in South America, nutria first came into the U.S. during the 1930s when fur production was in full swing. As a result of some escaping into the wild, their population exploded and since then, it's become one big nuisance for the state of Louisiana. Looking like a cross between a giant rat and a duck thanks to its webbed feet, it's overtaken the wetlands that run along the Gulf of Mexico. This is a coastline already disappearing at a rate of 35 square miles (90.1 square kilometers) per year as a result of both natural and human disturbance, but nutria further fuel this erosion, as they devour plants necessary for keeping the soil from washing away. State officials estimate over 100,000 acres (40.5 hectares) have been damaged as a result [source: Martel].
Efforts to control these critters over the past decade have ranged from state initiatives to market nutria meat as a viable commodity (and therefore foster hunting practices) to even offering bounties of $4 for each one captured [source: Martel].
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