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HA3 Effects of Multiple Stressors on Marine Resources
() Diagnosing causes of impairment in coastal ecosystems.
Jordan, S1, Engle, V1, 1 USEPA Gulf Ecology Division, Gulf Breeze, FL, USA
ABSTRACT- Estuarine and coastal ecosystems are challenged by excessive burdens of nutrients, sediments, and toxic contaminants, in combination with loss and degradation of essential habitats, alterations in the delivery of freshwater, and unsustainable resource uses. The terms diagnosis and diagnostics are applied to methods for determining causes of ecological impairment in systems subject to multiple sources of stress and disturbance. Diagnosis in the classical sense involves a comprehensive assessment of ecosystem health relative to a baseline condition of minimal impairment, followed by inferential reasoning about causes (effects-based approach). The term diagnostics also has been applied (less appropriately) to stressor-based approaches that employ mechanistic systems models, or use deductive methods analogous to toxicity identification evaluations. Despite the obvious management need to identify causes of impairment, complex coastal systems pose significant challenges. Among the challenges are the general lack of data to fully evaluate ecological impairment, and difficulties with the idea of causation. Proximal causes of biological impairment involve molecular and physiological responses to an individual organism′s immediate environment. Intermediate causes may be associated with time-integrated loads of contaminants to a system, or disturbances of the physical environment that affect populations and communities of organisms. At the most general (ecosystem) scale, causes may be as remote and diffuse as policy decisions about land use, water allocations, economics, and social welfare. Restoration and protection of coastal ecosystems will require thousands of incremental local actions in concert with regional, national, and global policy decisions. We suggest that a variety of diagnostic models is needed to inform management and policy at appropriate scales, from minutely detailed assessments of small watersheds, to global analyses of how emergent ecosystem properties correlate with major societal choices. At all scales, diagnosis must be based on sound science to avoid decisions based on untested assumptions and local biases.
Key words: Estuaries, Coastal ecosystems, Multiple Stressors, Diagnostics
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