Impact Assessment

Abstract

A common monitoring problem is: Describe the effect of an environmental alteration on the abundance of a given species at the ‘Impact’ site. Harbors, breakwaters, developments, sewage outfalls, oil platforms, coastal power plants and recreational access – and removals or redesigns of these – are examples in the marine environment, and plants, invertebrates and fish are typical populations of concern. The Impact site is defined naturally in some cases, as a bay or estuary, but arbitrarily in others, as a region surrounding the alteration. Before permitting such alterations, decision makers review predicted effects. These are often subjective, widely varying, and wrong. Monitoring and assessment can aid later decisions: to close the alteration down, modify its design or operation, require mitigation or compensation, allow expansion, or collect further data. By exposing error, it helps keep predictors honest; by adding information, it improves future decisions.