An ecosystem—like all systems—is made up of many different parts working together. But what happens when that system gets out of balance?
One thing that can stress an ecosystem is adding a new species. An invasive species is any plant or animal that lives in an ecosystem where it does not occur naturally and where it causes harm. Many invasive species come to a new ecosystem because people moved them there, either on purpose or by accident. In their new locations, invasive species do not have the predators, competition, or diseases that keep them in check in their native area. Without these controls, they can take over a habitat, making it difficult for native species to thrive.
Paths to Invasion
There are many ways invasive species end up in a new location, far away from their native range. In some cases, people intentionally bring them to the new area, not realizing the damage they could cause. For example, the nutria was brought to the United States from Argentina in the 1930s to produce fur. Now there are millions of them in the wild, causing tremendous damage to crops and waterways.
In many cases, these species are “hitch-hikers” along for the ride when people move barges, boats and trailers, cars and trucks, animals, commercial goods, food, or clothing. Without realizing it, people transport these species to a new ecosystem.
Common Characteristics of Invasive Species
The more of these characteristics a species possesses, the more likely it is to be invasive:
- Tolerates a wide range of conditions.
- Produces lots of seeds or eggs.
- Has few natural controls such as predators, competition, or disease.
- Has a long growing season.
- Needs a short amount of time to reproduce.
A Worldwide Problem
Invasive species are a problem around the world as they crowd out native species and change habitats. Once they have taken hold in an ecosystem, invasive species are almost impossible to remove. Controlling invasives is very time-consuming and expensive.
Invasive species are not new, but because of more worldwide travel and shipping of goods, the number of new invasions continues to increase. In the United States alone, scientists estimate there are about 7,000 invasive species, including plants, mammals, birds, amphibians, reptiles, fish, and insects. Some have caused major environmental damage. Together, they account for about $138 billion in costs to agriculture, forestry, and other segments of the United States economy.
How to Prevent Invasive Species
The best way to manage invasive species is to prevent their spread. You can help stop the spread of harmful invaders in your community in the following ways.
Gardening
- Don’t grow plants known to be invasive. If you don’t know it, don’t grow it!
- Avoid using seed mixtures, especially ones labeled “wildflowers.”
- Landscape with plants native to your area.
Boating and Fishing
- Never move water, animals, or plants from one body of water to another.
- Do not release live fish, including bait, into a new body of water.
- Wash all boating and fishing gear after use to prevent accidentally spreading invaders.
Pets
- Get any non-native pets from trustworthy dealers only.
- Don’t release any pets or aquarium fish into a native habitat or natural body of water.
Take Action!
- Tell others about the harm that invasive species cause.
- Volunteer to help remove invasive plants from your local park or nature reserve.
Source: Adapted from “What You Can Do to Prevent Species Invasion.” Union of Concerned Scientists.
Discussion Questions
- What is an invasive species?
- How are invasive species harmful?
- How do invasive species spread to new locations?
- What can you do to prevent the spread of invasive species?
