ECOSYSTEM MANAGEMENT AND THE CONSERVATION OF AQUATIC BIODIVERSITY ANDECOLOGICAL INTEGRITY

Ecologically effective ecosystem management will require the developme nt of a robust logic, rationale, and framework for addressing the inhe rent limitations of scientific understanding. It must incorporate a st rategy for avoiding irreversible or large-scale environmental mistakes that arise from social and political forces that tend to promote frag mented, uncritical, short-sighted, inflexible, and overly optimistic a ssessments of resource status, management capabilities, and the conseq uences of decisions and policies. Aquatic resources are vulnerable to the effects of human activities catchment-wide, and many of the landsc ape changes humans routinely induce cause irreversible damage (e.g., s ome species introductions, extinctions of ecotypes and species) or giv e rise to cumulative, long-term, large-scale biological and cultural c onsequences (e.g., accelerated erosion and sedimentation, deforestatio n, toxic contamination of sediments). In aquatic ecosystems, biotic im poverishment and environmental disruption caused by past management an d natural events profoundly constrain the ability of future management to maintain biodiversity and restore historical ecosystem functions a nd values. To provide for rational, adaptive progress in ecosystem man agement and to reduce the risk of irreversible and unanticipated conse quences, managers and scientists must identify catchments and aquatic networks where ecological integrity has been least damaged by prior ma nagement, and jointly develop means to ensure their protection as rese rvoirs of natural biodiversity, keystones for regional restoration, ma nagement models, monitoring benchmarks, and resources for ecological r esearch.