Water Assessment and Criteria

Abstract

The most useful measures of biotic integrity of aquatic systems reflect the biological responses of organisms and their populations to the prevailing (past and present) environmental conditions. The ability to classify the quality of streams and rivers (with indigenous biological assemblages) provides information that is integral for making management decisions and identifying anthropogenic impacts (35). Development of an “Index of Biotic Integrity” (IBI) using a combination of 12 community parameters (metrics) for fish assemblages provided direction into a new and innovative way of obtaining this type of information (24). The combination of these community attributes (multimetrics) into an IBI provided a classification of the quality of fish communities as a measure of water/habitat quality. The metrics used in the construction of the IBI encompassed several levels of fish community structure and function—species composition/richness and information on ecological factors (trophic structure and health). Successful application of multimetric indices depends on selecting the appropriate metrics used to describe and delineate the biological assemblages (36). The use of multimetrics provides a way of measuring the response of biological assemblages at several levels of organization (e.g., composition, condition, and function) to anthropogenic influences, and these measurable biological attributes can be tested, verified, and calibrated for use in the respective geographical areas of study.