A living species which, by its presence or absence, abundance or scarcity, allow to assess the degree of pollution of water or air. (e.g : lichens for the atmosphere, salmonids for rivers, etc.)
Specie or group of species whose observed characteristics (occurrence, abundance, biomass, biological traits, etc.) provide an indication of the level of environmental degradation. A bioindicator is therefore subject to measures to indicate the presence or effects of pollutants and thus allows the quality of the environment in which it is collected to be assessed. It can be considered complementary (especially for the spatial distribution of pollution, the characterization of synergies, the gradual pollution, etc.) of networks of physicochemical measurements.