Determining the Association between the Structure of Stream Benthic Macroinvertebrate Communities and Agricultural Best Management Practices

.......................................................................................................................................... ii Acknowledgements ........................................................................................................................ iv List of Tables and Figures............................................................................................................. vii List of Abbreviations ................................................................................................................... viii 1.0 Introduction ............................................................................................................................... 1 1.1 Agriculture and the Environment .......................................................................................... 1 1.2 BMPs as a Mitigation Tool for Agricultural Impacts on River Systems .............................. 3 1.3 Effectiveness of BMPs at Mitigating Negative Impacts from Agriculture ........................... 4 2.0 Research Goal ......................................................................................................................... 11 2.1 Objectives ............................................................................................................................ 11 2.2 Hypothesis ........................................................................................................................... 11 3.0 Methods................................................................................................................................... 12 3.1 Study Area ........................................................................................................................... 12 3.2 Site Selection ....................................................................................................................... 14 3.3 Identifying the Degree of Hydrological Connection for BMPS ......................................... 17 3.4 Description of Riparian Vegetation and Tile Drainage ....................................................... 19 3.5 BMP Metrics ....................................................................................................................... 20 3.6 Field Sampling .................................................................................................................... 23 3.6.1 Benthic Macroinvertebrates .......................................................................................... 23 3.6.2 Habitat Assessment....................................................................................................... 24 3.6.3 Water Chemistry ........................................................................................................... 25 3.7 Data Analysis ...................................................................................................................... 26 3.7.1 Association between BMP Metrics and Water Parameters .......................................... 28 3.7.2 Stepwise Ordination Regressions and Variance Partitioning ....................................... 28 4.0 Results ..................................................................................................................................... 31 4.1 Land Use Summary ............................................................................................................. 31 4.2 BMP Abundance and Composition ..................................................................................... 31 4.3 Degree of Hydrological Connection for BMPs ................................................................... 33 4.4 Habitat Assessment ............................................................................................................. 34