ABSTRACT
This chapter provides an overview of our approach to ecological causal assessment: list candidate causes, derive evidence for each, and identify which is best supported by the evidence. The approach is illustrated with a case of a fish kill in the Kentucky River. The process is implemented in three main steps: formulate the problem, derive evidence, and form conclusions. Problem formulation identifies the subject and scope of the assessment by defining: the effects of concern, the spatial and temporal extent of the problem, and the candidate causes that will be explored. Even when the issue being addressed by the causal assessment seems obvious, it is worth taking a step back to carefully articulate the problem being investigated and the candidate causes under consideration. Completing the steps of causal assessment can strengthen the scientific basis for decisions made to improve biological conditions.
