Linked from
The 106 pages that link to Bioindicator, each with the reason it gives.
Aquatic insectNarrower topic: Aquatic insect communities can signal pollution and habitat change.
FrogNarrower topic: Frog populations can signal changes in water quality and habitat conditions.
Indicator speciesNarrower topic: Indicator species are one form of biological indicator.
PlecopteraNarrower topic: Stoneflies are used as indicators of stream habitat and water quality.
DesmidialesNarrower topic: Desmid communities can reflect water chemistry and habitat quality.
MergusNarrower topic: Mergansers can reflect the condition of fish-bearing aquatic habitats.