Rapporteur’s Report

Summary of Presentations

The task of defining ecosystem health is difficult because of the complex nature of ecosystems and the multitude of problems that must be considered. The initial section, therefore, sets the stage by considering the definition of ecosystem health, its relationship to and comparison with the health services, its relationship to the delivery of ecosystem services, and its utility in communicating with the public.

Rapport suggests that ecosystem health is a concept around which a new integrative science can emerge by drawing from a number of disciplines including the biological, social, and health sciences. He cautions, however, that the health analogy cannot be followed strictly because of the multitude of problems associated with ecosystem variability and responses.

Calow argues that definitions of health boil down to the assumption of a core norm, from which deviations represent the state of health. This norm can be defined in various ways, not all of which are acceptable. He concludes that since the ecosystem approach is often used to manage ecosystems for human health and services, it is possible to define states of ecosystem health in these terms.

Ramade summarizes a number of qualitative and quantitative criteria for the abiotic and biotic components of an ecosystem that included structural and functional criteria for defining a “healthy” ecosystem. He concludes that much additional research is needed to define ecosystem health, especially in the assessment issue areas of key species identification; improved knowledge of functional bioindicators; impingement of anthropogenic perturbations; chemical cycle influence; and, impingement at regional and landscape scales.

Pratt and Cairns develop the concept of “ecosystem services,” and summarize the activities or functions of ecosystems that are perceived to be beneficial to human society. They then discuss the correlation that should exist between ecosystem health and ecosystem services, a relationship that is not well documented.

Amaral-Mendes outlines some of the approaches used in toxicology to evaluate human health effects of exposure to chemicals. Also, he notes that in the field of ecotoxicology, the evaluation of the toxicological effects of human exposure to toxic compounds relies on a multimedia approach to the analysis of environmental risk and pollution control strategies. Although believing that more agreement is needed on the bases for exposure assessment and the processes involved, he suggests that the multimedia approach to the evaluation of human environmental health provides an indispensable link to ecosystem health. He then points to recent developments in the field of biomarkers and outlined their uses to determining changes in biological responses that can be related to exposure to an environmental contaminant.