Associated Use Attainment Response between Multiple Aquatic Assemblage Indicators for Evaluating Catchment, Habitat, Water Quality, and Contaminants

Use attainability analysis (UAA) at a watershed scale typically relies on the assumption that indicator organisms are responding similarly to the same environmental stressor. Factors explaining variance in fish, crayfish, and macroinvertebrate assemblage structure and function were investigated with emphasis on catchment and reach scale land use, habitat, contaminants, and water quality variables. Habitat quality scores ranged from 25 to 85 (average 61.36±10.08). The substrate score, instream cover, riffle-run score, and channel score were primary factors contributing to declining habitat quality. Factor analysis found that four factors explained 69% of the contributed variance in fish assemblage, two factors accounted for 56% of variance in macroinvertebrate assemblages, and two factors explained 49% of the variance in crayfish assemblages. Overall drivers of assemblage structure were associated with broad scale issues of wastewater treatment, groundwater, and land use. Our results show that fish, macroinvertebrate, and crayfish assemblages respond to similar broad scale stimulus; however, the specific constituents responsible for the stress may vary with the magnitude of the cumulative stress, which may be expressed by each organismal group differently. Our data suggest that varying organismal groups can respond independently and stress reflected in one assemblage may not necessarily be observed in another since each organismal group is measuring different aspects of the environment