We are researchers at Carnegie Mellon University, working on a project related to "biosensing", "biomarkers" and "bioindicators". We want to know how plants, animals and other organisms can be used to monitor the environment or tell us something about our ecosystem. In the name of science and for fun, please share some examples from your own work or personal experience.
Many species of lichen are very sensitive to air pollution, and are used as kind of bioindicators at least in the northern parts of the globe. In industrial regions in Northern Europe, for example, some lichens were absent for most of the twentieth century, but after better pollution control they re-emerged in many areas during the last few decades of the century.
Usnea ("old man’s beard") are a type of lichen that grow on the branches of trees (especially spruces) and are very dsitinctive in old forests. These lichens also often disappear close to industrial areas and factories, and slowly re-appear if the levels of air pollution decrease.