How do we assess the impacts of human activities on natural ecosystems? What can the biota tell us about the environment and its response to natural stress? Introduction

Introduction What can the canary in the coal mine tell us? Historically, canaries accompanied coal miners deep underground. Their small lung capacity and unidirectional lung ventilation system made them more vulnerable to small concentrations of carbon monoxide and methane gas than their human companions. As late as 1986, the acute sensitivity of these birds served as a biological indicator of unsafe conditions in underground coal mines in the United Kingdom. Since human health concerns continue to drive the development and application of bioindicators, the loss of ecosystem services (e.g., clean air, drinking water, plant pollinators) has increasingly focused our attention on the health of natural ecosystems. All species (or species assemblages) tolerate a limited range of chemical, physical, and biological conditions, which we can use to evaluate environmental quality. Despite many technological advances, we find ourselves turning to the biota of natural ecosystems to tell us the story of our world.