Community Approaches to Monitoring

Where no single important resource can be identified, the question of what to monitor can be difficult, especially if the amount of change that has occurred must be verified statistically. Monitoring programs have therefore often focused on the measurement of indicator species and derived values such as diversity. Actual marine monitoring data show that the variability of single species can be so great that very high numbers of samples are often required to detect even large changes. Derived variables can also be ambiguous indicators of the direction of biological change. In contrast, multivariate techniques directly compare species composition across all samples. They contain more information about community patterns, and can be more sensitive and statistically powerful indicators of change than the parameters described above. We demonstrate quantification of community changes along wastewater outfall gradients with multivariate techniques.