What is the term for organisms that indicate the level of pollution in the environment?

Indicator species are organisms that provide insight into the health of an ecosystem and the level of pollution present in the environment. These species are sensitive to environmental changes and can reflect the quality of their habitat. For example, if certain indicator species decline or disappear from an area, it can suggest that pollution levels have risen, or that other harmful changes are occurring in the ecosystem.

In contrast, endemic species are native to a specific location and are not necessarily linked to pollution levels. Invasive species refer to non-native organisms that spread rapidly and can harm native ecosystems. Keystone species play a critical role in maintaining the structure of an ecological community, but they do not specifically indicate pollution levels. Therefore, indicator species are the most accurate term for organisms that signal the degree of pollution or environmental change.