Measuring Biological Integrity: Lessons from Streams

The concepts of biological integrity and ecological health are not new. This chapter outlines the important lessons of the past decade relevant to measuring and protecting biological integrity or ecological health. Two weaknesses permeate most past approaches to protect water resources: a narrow conception of the factors responsible for degradation and a limited perspective on the components of biological integrity. However, organic material is critical to the biota of streams. Biological integrity continues to decline under a solely chemical focus; a similar result is likely if the elements, but not the assemblages and processes of biotic integrity, are protected under proposed biodiversity legislation. With increased understanding of the complexity of biological systems and complex influences of human actions on those systems, more integrative approaches to assessing biological integrity have developed. A sound biological monitoring program designed to assess biological integrity should have several attributes.