Landscape scale and contaminant effects on aquatic assemblage structure

The purpose of this research was multifaceted. We investigated the relationship between stressor response models associated with an urban landscape, multiple assemblage response, and fish assemblage nutrient response. Essentially the study area for this research encompassed data collected from across the State of Indiana. The nature of the analysis performed resulted in this volume of data being compartmentalized into discreet spatially driven subsets that were analyzed independently.;To determine the responsiveness of fish assemblages to stressors associated with an urban landscape we targeted the Salt Creek Watershed. Salt Creek is a Lake Michigan tributary in Northwest Indiana, USA, which drains a watershed experiencing rapid urbanization as part of the expansion of the Greater Chicago metropolitan area. The watershed supports a managed coldwater fishery comprised principally of the introduced Skamania strain of the steelhead (Oncorhynchus mykiss). The sustainability of this watershed depends on the proper management of warm water tributaries and salmonid water in the Salt Creek mainstem. Twenty-three fish species were collected in the Salt Creek watershed and were numerically dominated by creek chub (Semotilus atromaculatus ) and green sunfish (Lepomis cyanellus) both of which are tolerant to a wide range of environmental conditions. Habitat quality, measured using the Qualitative Habitat Evaluation Index (QHEI), showed that the watershed was generally degraded and scores ranged from 12--69. Fourteen parameters were significantly correlated with reach scale ecological health and biological integrity. Factor analysis found three factors explained 69% of the contributed variance in the watershed fish assemblage. The first factor included habitat measures comprised of the QHEI score and three of its metrics (i.e., channel, riparian and instream cover scores) and explained 36 percent of data variability. The second factor was comprised of two contaminants (i.e., TDS and Chloride) and one local-scale land-use variable (Agriculture) that explained an additional 20 percent of the variability. The third factor was comprised of two local scale land-use variables (i.e., riparian zone and water) explaining 13percent of the variability.;To evaluate the responsiveness of multiple aquatic assembles to watershed stress we target the Big Oaks National Wildlife Refuge. The Big Oaks National Wildlife Refuge encompasses the northern 51,000 acres of the former Jefferson Proving Ground (JPG) which was used from 1940--1995 as a munitions testing facility. Since 2000 the U.S. Fish and Wildlife Service has utilized the northern 51,000 acres of JPG for ecosystem-based management in conjunction with continued use by the U.S. Department of Army and Indiana Air National Guard for air-to-ground training. An investigation of factors that explained the variance in fish, crayfish, and macroinvertebrate assemblage structure and function was based on catchment and reach-scale land use, habitat, contaminants, and water quality. Our results show that fish, macroinvertebrate, and crayfish assemblages respond to similar broad scale stimulus; however, the specific physical/chemical constituent responsible for the stress may vary, and the realized magnitude of the overall stress on the system 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.;Finally, we evaluated nutrient response in fish assemblages targeting a large data set collected from the Indiana portion of the Corn Belt Plain Ecoregion. This study is conducted as part of the U.S. Environmental Protection Agency (USEPA) desire to development regional nutrient thresholds. The first objective of this study is to develop a biotic model capable of determining the contributions of various nutrients, including Nitrogen components and TP, in streams using fish assemblages. The second objective is to establish an approach for designating defensible nutrient biotic index (NBI) score thresholds and corresponding nutrient concentrations, above which fish assemblages show alterations due to increasing nutrient concentrations. (Abstract shortened by UMI.)...