Indicator species are unique environmental indicators as they offer a signal of the biological condition in a watershed or ecosystem, and are a warning system that pollution has entered the food web.

The term indicator species is a bit misleading, as indicators are often whole groups of flora/fauna types which can be used to assess environmental condition.

Most indicator species are fish, invertebrates, periphyton and macrophytes.

See also

• Keystone species
• Flagship species