Understanding Invasive Species in IB ESS
In IB Environmental Systems & Societies (ESS), invasive species are a key topic under ecosystem stability and biodiversity. An invasive species is a non-native organism introduced — intentionally or accidentally — into an ecosystem where it causes harm to the environment, economy, or human health. These species outcompete native organisms, disrupt ecological balance, and reduce biodiversity.
Causes of Invasive Species Introduction
Human activity is the main driver of biological invasions. Species are often transported across regions through:
- Global trade and travel — seeds, insects, and small animals hitchhike in cargo or luggage.
- Agriculture and aquaculture — non-native plants or fish introduced for economic reasons escape containment.
- Pet trade and ornamental gardening — exotic animals or plants released into the wild.
- Climate change — warmer temperatures allow species to expand into new regions.
The IB ESS syllabus emphasizes understanding how human systems interact with natural systems, and invasive species represent a perfect example of this link.
Ecological Impacts of Invasive Species on Ecosystems
Invasive species often outcompete native species for food, light, and habitat. This can trigger a cascade of ecological effects:
- Biodiversity loss: Native species decline or go extinct when unable to compete.
- Disruption of food webs: Predation and competition alter trophic relationships.
- Habitat alteration: Some invasive plants, like kudzu, physically change ecosystem structure.
- Introduction of new diseases: Invasive organisms may carry pathogens that harm local wildlife.
