How Do Invasive Species Affect Biodiversity and How Can They Be Controlled?

Biodiversity is the world around us.  It is the variety of life on Earth from the genes that make up individual organisms to the species interacting with one another and the ecosystems that provide important services to people.  

The Impact of Invasive Species

Invasive species – ones that have been introduced to an ecosystem due to human-related activities like trade, travel or horticulture practices - are now common in the U.S. and compromising our nation’s biodiversity. Alarmingly, invasive species are a major factor in an estimated 40 percent of endangered species listings and are one of the five main drivers of global biodiversity loss. 

Through predation, competition for resources like food and water and transmission of diseases, invasive species are causing the decline of native species and disrupting the important interactions that contribute to healthy native ecosystems.  

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Janet Horton/Alamy Stock Photo

As native species are lost, so is some of the evolutionary history, functions, and species interactions that contribute to the diversity of healthy ecosystems. This loss can lead to degraded ecosystem services and the inability for an ecosystem to protect itself from major disturbances.  

When species disappear from an ecosystem, those that depend on them for food, pollination or other needs are also impacted. This can decrease overall productivity and resilience. At a certain point, it becomes a “Jenga effect”– pull out too many pieces, and eventually the structure collapses.  

For example, the growing and expanding populations of lionfish, who have very few predators, is harming native coral reef ecosystems in the Atlantic, Gulf of Mexico and Caribbean. When lionfish prey on herbivores who eat algae, this disruption in the food chain promotes algae growth which is detrimental to the health of coral reefs.  

Coral reefs are already struggling due to climate change and pollution and the threats from lionfish are threatening the collapse of these ecosystems. Currently, there are seven coral species listings in lionfish-infested areas.  

It is impossible to mention invasive species without mentioning climate change. Climate change is exacerbating the spread of invasive species and changing environmental conditions to make it easier for introduced plants and animals to get a foothold which puts additional pressure on some of the already at-risk species native to the area.  

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Marsha Skoczek/NOAA

Taking Action Against Invasive Species

Defenders is fighting invasive species. We are initiating and supporting invasive species removal programs, like clearing invading sunfish from headwater streams to make room for endangered laurel dace, and fighting for substantial funding for invasive species resistance. We are advocating for policies that will require screening and inspection before plants and animals come into the country. 

You can help too. From planting native plants in your garden to supporting native pollinators to checking your boat for nonnative stowaways before you set sail to advocating for removal programs action on Capitol Hill, controlling the spread of invasive species is a collective effort that starts with us.  

Addressing Biodiversity Crisis Through Policy

The U.S. lacks a comprehensive and coordinated approach to tackling the five main drivers of the biodiversity crisis, one of which is invasive species. Defenders is actively working with members of Congress to implement a national biodiversity strategy. There are at least 32 federal agencies with shared responsibilities for invasive species prevention, eradication, and control efforts, though coordination is often lacking. A national biodiversity strategy would address the extinction crisis by requiring more effective and coordinated use of laws and policies to protect biodiversity from invasive species and other threats.  

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Joanne McCubrey

Promoting Native Plant Sustainability 

Native plants are the foundation for healthy ecosystems and the environment.  Growing our native seed supply and prioritizing native seeds in replanting and restoring our landscapes over exotic plants helps to promote healthy, native systems for wildlife and people. A new report shows that significant work is needed to strengthen native seed production and distribution to keep ecosystems intact. Native wildlife depends on healthy native plants over exotic plants because they co-evolved together. Native plants are the very foundation of life for at-risk species and provide species with shelter and sustenance they need to thrive. Defenders is advocating for increasing our nation’s native seed supply to keep our lands healthy, natural, and resilient to climate change.   

International Collaboration for Wildlife Protection

Wildlife trade treaties and laws like the Convention on International Trade in Endangered Species are important for stopping the spread of invasives and Defenders works with countries and partners around the world on enforcing and strengthening these protections.  

Defenders is committed to safeguarding ecosystems by advocating for conservation measures for native wildlife and their habitats as well as ecosystem restoration efforts.