9.8 Invasive Species

What Makes a Species Invasive

An invasive species is a non-native organism introduced to a new ecosystem (often by humans) that spreads rapidly and causes ecological or economic harm. They thrive because they lack natural predators, parasites, or competitors in the new environment. Introductions occur through global trade, travel, ballast water, and intentional releases (e.g., pets, agriculture).

Ecological and Economic Impacts

Invasive species outcompete native species for resources like food, light, and space, reducing biodiversity and disrupting food webs. Examples include zebra mussels clogging waterways and kudzu smothering native plants. They cause billions in damage yearly through crop loss, infrastructure damage, and costly control/eradication efforts.

Management Strategies

Prevention (inspecting cargo, regulating pet trade) is the most cost-effective control. Once established, methods include mechanical removal, chemical pesticides/herbicides, and biological control (introducing natural predators, which carries its own risks). Early detection and rapid response are key to limiting spread and protecting native ecosystems.

Key terms

Invasive species

A non-native organism that spreads rapidly in a new ecosystem, causing ecological or economic harm.

Why invasive species thrive

They lack natural predators, parasites, or competitors in their new habitat.

Common introduction pathway

Global trade and travel, such as ballast water from ships or intentional pet/agricultural releases.

Biological control

Using natural predators or parasites to manage invasive species populations; carries risk of unintended ecological effects.

Best management approach

Prevention (inspection, regulation) is the most cost-effective way to limit invasive species introduction and spread.

Try an AP-style question

What is an invasive species?

1. A non-native species that spreads and causes harm
2. A declining native species
3. Any species that migrates each season
4. A species found only in water