Invasive or a Nuisance?

We often use the term invasive to describe any critter or plant that is causing a disturbance, but there are quite a few specific characteristics of a species that deem it truly invasive. For example, all people can vouch for the fact that mosquitos are frustrating and can cause harm to humans, but many species of mosquitos are native to the area, which makes them not invasive! For a species to be labeled as invasive, it must have some or most of the following characteristics:

​Non-native to the Area it is Invasive to

​This means that in order for a species to even be considered as invasive, it needs to be occupying a habitat or area that it is not native to. Many invasive species get to their new locales via human introduction and in most cases it’s a complete accident. Because of human beings’ ability to travel with ease from region to region around the world, the massive trade industry between countries, the manufacturing of goods worldwide and even the international pet trade, animals are constantly being introduced to areas where they are not native to. Some animals will be unable to transition to new habitats, some will survive but not cause much disturbance and others will completely take over.

​Harmful to the Economy, Environment or Human Health

In addition to being non-native, the introduced species must cause some kind of damage to the area it has been introduced to. With invasive species’, harm can be see when it costs a lot of money to remove the animals or any damage they have caused, they harm the environment they are introduced to including by decreasing biodiversity, or causing harm to humans because of disease, irritation if it’s a plant, or any kind of dangerous threat.

Biovidersity:
How many species are present in an ecosystem or habitat. Greater Biodiversity is often indicative of a healthier ecosystem.

An example of an invasive species that has caused economical damage to an area is the invasive Asian Carp within the Mississippi river. Four species of carp have taken over the river after being introduce from Asia. They are the Grass Carp, Black Carp, Bighead Carp and Silver Carp. Within the Mississippi river system, aside from costing money to manage, they have negatively impacted the biodiversity of the area, which has also negatively impacted the fishing industries. For 15 years, scientists, fishermen and community members have been trying to manage these aquatic pests spending a grand total of 1.5 billion dollars in an effort to keep them out of the Great Lakes, where their impact on the fishing industry could be irreversible. As of now, they are mostly managed by electric “herding”, which is when boats use sound waves and electric currents to drive the fish into 1,000 foot long nets. Female carp are able to lay up to 5 million eggs at a time, making it near impossible to manage the populations without continuously spending on resources and manpower. One idea for the future that may allow for some kind of long-term management, at least to keep the fish out the Great Lakes, is to create an underwater dam that blocks fish using the same electric currents and sound waves used to control them now by boats!

Photo from leafchronicle.com, submitted by U.S. Fish and Wildlife. Click on image to go to Leaf Chronicle article on the invasive Asian Carp.

​Ability to Reproduce Rapidly/Grow Quickly

​One of the characteristics that makes invasive species so difficult to manage, as mentioned with the invasive carp species of the Mississippi River, is their ability to reproduce rapidly and grow quickly. What this means is that many invasive species have a very short time between when they are born and when they are mature enough to reproduce themselves. Not only do they reach maturity quickly, but they also tend to have a large number of offspring. Individuals reaching maturity quickly and the ability to produce huge numbers of offspring results in the perfect storm for extreme population growth. 

​In the case of plants, the ability to grow quickly is key. Many invasive plants will take over areas because of continual growth cycles with no distinct growing seasons as well as the ability to produce large amounts of seeds at once. One example of an invasive plant species that visibly consumes landscapes because of its extreme growth rate is the kudzu, or “mile-a-minute” vine. It has also been known as “the vine that ate the south.” Kudzu is native to Japan and southeast China where it grows naturally in harmony with other members of the ecosystem; however, the warm, wet climate of the south gives the kudzu vine the opportunity to grow and spread much more rapidly throughout the year.

Kudzu consuming the landscape

Kudzu consuming the landscape

Kudzu consuming the landscape

Wide Range of Adaptations

This is not something that invasive species must have to be called invasive, but it is true that many invasive species do have a wide range of adaptations that allow them to be well suited to thrive in any environment. For animals, one adaptation that is key is the ability to eat a wide range of food. Animals that are adapted to have broader diets will be more successful in new habitats than animals with specific consumption needs. The wide range of adaptations that help invasive species survive in their new habitats aren't always super cool, but they tend to be things that allow the animal or plant to transition to new areas with ease. This is also one of the reasons invasive species are able to spread quickly and easily when introduced to a new place. For plants, one adaptation that makes them very successful when invading new areas is the ability to grow in a range of different temperatures and moisture levels. Plants that aren't able to grow in multiple areas tend to have very specific growing needs, whereas invasive plants have a broad range of temperatures they can thrive in as well as the ability to survive with lots of moisture or little moisture throughout the year.

Invasive species with big appetites from top to bottom: Burmese Python, Black Spiny-Tailed Iguana, Cane Toad, Lionfish.

DANGER: Invasive Species with Big Appetites

Burmese Python

Black Spiny-Tailed Iguana

Cane Toad

Lionfish

How can you help?

Many invasive species get from place to place by hitch-hiking with humans. This can be from latching onto trade-ships, or even attaching to a camper on a weekend in nature.

Some ways that you can help to prevent the spread of invasive species are by planting native plants in your yard or garden, cleaning off boots and clothes after a hike in an area with known invasives, rinsing off your boat after each use to get rid of aquatic hitchhikers, finding the appropriate way to manage household pets, reporting sightings of invasive species, volunteering with a removal project, and by researching invasive species near you!