title: Effects of Best Management Practice on Ecological Condition: Does Location Matter?
abstract: Best management practices (BMPs) are increasingly being promoted as a solution to the potentially adverse effects agriculture can have on aquatic systems. However, the ability of BMPs to improve riverine systems continues to be questioned due to equivocal empirical evidence linking BMP use with improved stream conditions, particularly in regard to ecological conditions. Explicitly viewing BMP location in relation to hydrological pathways may, however, assist in establishing stronger ecological linkages. The goal of this study was to assess the association between water chemistry, benthic macroinvertebrate community structure, and the number and location of agricultural BMPs in a catchment. Macroinvertebrate and water samples were collected in 30 small (<12 km(2)) catchments exhibiting gradients of BMP use and location in the Grand River Watershed, Southern Ontario, Canada. Stepwise regression analysis revealed that concentrations of most stream nutrients declined in association with greater numbers of BMPs and particularly when BMPs were located in hydrologically connected areas. However, BMPs were significantly associated with only one metric (%EPT) describing macroinvertebrate community structure. Furthermore, variance partitioning analysis indicated that less than 5% of the among site variation in the macroinvertebrate community could be attributed to BMPs. Overall, the implemented BMPs appear to be achieving water quality improvement goals but spatial targeting of specific BMP types may allow management agencies to attain further water quality improvements more efficiently. Mitigation and rehabilitation measures beyond the BMPs assessed in this study may be required to meet goals of enhanced ecological condition.
authors.affiliation: Department of Geography, Western University & Canadian Rivers Institute, 1151 Richmond St, London, ON, N6A 5B7, Canada.
authors.forename: Roger
authors.initials: R
authors.lastname: Holmes
authors.affiliation: Department of Geography, Western University & Canadian Rivers Institute, 1151 Richmond St, London, ON, N6A 5B7, Canada.|Prothea Srl, Milan, Italy.
authors.forename: David G
authors.initials: DG
authors.lastname: Armanini
authors.affiliation: Department of Geography, Western University & Canadian Rivers Institute, 1151 Richmond St, London, ON, N6A 5B7, Canada. adam.yates@uwo.ca.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Yates
mesh_terms: D000383:Agriculture; D059001:Aquatic Organisms / Q000502:physiology; D003247:Conservation of Natural Resources; D004463:Ecology; D004784:Environmental Monitoring; D009864:Ontario; D045483:Rivers / Q000737:chemistry*; D014876:Water Pollution / Q000032:analysis*; D060753:Water Quality
keywords: Agriculture; Benthic macroinvertebrates; Best management practices; Hydrologic connectivity; Stream ecosystems; Water chemistry