Some Limitations of Indicators and Their Place in Monitoring Schemes

Indicators of marine environmental quality in problem oriented monitoring must be matched to management needs. Indicators, carefully chosen, applied, and interpreted, can help us understand environmental status, and perhaps help to forecast environmental changes. Understanding the causal mechanisms and inter-relationships underlying changes in indicator values usually relies on models derived from previous research. The management focus and utility of marine environmental monitoring programs would be greatly improved by 1) clear definition of management objectives and information needs; 2) more direct representation of management values in the indicators selected for monitoring; 3) specification of appropriate management actions at different threshholds in the monitored indicators; and 4) design of statistically sound sampling with explicit recognition of credible impact hypotheses, desired detection limits, and ambient variability. For many indicators, indexes may be an effective means of describing and communicating environmental trends.