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DETERMINING THE CAUSES OF ADVERSE EFFECTS IN NEAR COASTAL ECOSYSTEMS: FROM TOXICITY IDENTIFICATION EVALUATIONS TO WATERSHED DIAGNOTICS
Citation:
Burgess, R M., K T. Ho, M Pelletier, D E. Campbell, M Cantwell, J R. Serbst, AND S Ryba. DETERMINING THE CAUSES OF ADVERSE EFFECTS IN NEAR COASTAL ECOSYSTEMS: FROM TOXICITY IDENTIFICATION EVALUATIONS TO WATERSHED DIAGNOTICS. Presented at The Society of Environmental Toxicology and Chemistry Annual Metting, Portland. OR, November 14-18, 2004.
Description:
Several approaches are available for evaluating adverse effects in near coastal ecosystems. These range from performing toxicity tests with individual organisms on water column and sediment samples to conducting macrofaunal compositional analyses on pelagic and benthic communities. Similarly, applicable endpoints vary from mortality and reproductive effects to ecological alterations. However, few approaches exist for identifying the actual causes of observed adverse effects. Consequently, very frequently, environmental scientists and managers know adverse effects like toxicity or environmental impairments are present but have no information on likely causes. This presentation will discuss the on-going evolution and development of an causal methods for identifying the causes of adverse effects in near coastal ecosystems. The first established causal approach for identifying active stressors in aquatic ecosystems were Toxicity Identification Evaluations (TIEs). Developed in the 1980s and 1990s, TIEs are used on water and sediment samples to assess the significance of toxic chemicals in causing observed adverse effects. TIEs have been applied to environmental risk assessments and contaminated site remediations. As the next step in the evolution of causal methods, we are developing watershed diagnostics. The watershed diagnostic approach is designed to determine the causes of adverse effects at the watershed scale as elicited by nutrients, toxic chemicals and clean sediments. To accomplish this, TIE methods will be used to determine the significance of toxic chemicals while stressor-specific indicators will be measured to assess the importance of other stressors. In order to definitively confirm the role of any given stressor as the cause of an observed adverse effect, a decision matrix will relate stressor presence in a water body to observed effects and stressor source. The ultimate goal of the watershed diagnostic approach is to provide environmental managers with a useful tool for protecting near coastal ecosystems.