Approaches to assessing and managing cumulative ecosystem change, with the Bay of Quinte as a case study: an essay

Rising concern for the future of humans and the earth's ecosystems provides the backdrop for an essay on approaches to assessing and managing ecosystem health. A review and critique of two rival metaphors of human health, illness and wellness, provide the staring point for evaluation of parallel approaches to the assessment and management of ecosystems. The limitations of the metaphors are noted for humans and ecosystems. The ‘impact assessment’ and ‘ecosystem approach’ concepts of ecosystem assessment and management are contrasted. As a case history, the nature and pace of change in the Bay of Quinte ecosystem are reviewed, spanning from colonization by the Empire Loyalists at the end of the 18th century through the current development of a remedial action plan for the ecosystem. The review includes the long-term scientific study of the Bay's response to point-source phosphorus control (Project Quinte) and the recent efforts to develop and implement a coordinated clean-up program (Remedial Action Plan). From the lessons of the Quinte experience, a framework is derived, combining the illness and wellness approaches to health. The framework deals with five topics: uncertainty and the precautionary principle; an ecosystem health scale; indicators of ecosystem health; maximum allowable change; and, regulation and planning. Uncertainty should not be used to justify inaction. A precautionary principle assumes that impacts will occur and places the burden of proof on the proponents of ecosystem disturbance. An ecosystem health scale is defined using current, original, and potential conditions. Restoration to the original condition is unlikely but provides a justifiable direction for actions to establish sustainability. Indicators of ecosystem health with sustainable ranges are preferred over end-points and thresholds. The concept of maximum allowable change is promoted with a tentative suggestion that a fifty percent rule might be used. Finally, an argument for the combined use of regulation and planning. Regulatory approaches tend to perpetuate confrontation. Planning can be used to lengthen the time-horizon from quarterly reports to generations and identify self-regulating codes of behaviour. The framework is briefly discussed and placed in a broader context linking humans and ecosystem, illness and wellness.