HR: 14:00h
AN: NB43B-03 INVITED     [Abstracts]
TI: Integrating Descriptive and Experimental Approaches to Identify Stressor Effects on Stream Benthic Communities
AU: * Clements, W
EM: willc@cnr.colostate.edu
AF: Colorado State University, Department of Fishery and Wildlife Biology, Fort Collins, CO 80523 United States
AB: Descriptive studies which compare composition of benthic macroinvertebrate communities upstream and downstream from contaminant discharges generally cannot be used to identify stressors or to demonstrate causal relationships between stressors and biological responses. In this study I describe results of stream microcosm and field experiments designed to support results of descriptive studies conducted in the metal-polluted Arkansas River, CO. Monitoring benthic communities before and after remediation of metal inputs provided correlative evidence that elevated heavy metal concentrations altered community composition and reduced abundance of metal-sensitive taxa. However, these field data were not especially useful for estimating safe concentrations of heavy metals that would be protective of benthic communities. Exposure pathways in the Arkansas River were quantified by measuring metal bioaccumulation in caddisflies (Trichoptera) collected upstream and downstream from metal inputs. Microcosm and field experiments were used to establish concentration-response relationships between heavy metals and several structural (abundance, richness) and functional (macroinvertebrate drift, community respiration) endpoints. Consistency of these responses was demonstrated by comparing results to a spatially extensive survey of metal-polluted streams in Colorado. This study demonstrates the power of integrating descriptive and experimental approaches for developing causal arguments and identifying stressors in ecological assessments.
DE: 4804 Benthic processes/benthos
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly