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Seasonal variation in the effectiveness of agricultural best management practices at reducing metabolism within agricultural streams in South Western Ontario: A paired catchment study
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The eutrophication of freshwater systems has become a global problem owing to anthropogenic increase in nutrient loading, particularly Nitrogen and Phosphorus. Over the past half century, the Laurentian Great Lakes have seen an acceleration of eutrophication because of increased population and human activity across the drainage basin. Eutrophication and the associated increase in algae biomass, can cause a range of impairments to the water quality, ecosystems functioning and ecosystem services of streams and receiving water bodies. For example, eutrophication can degrade the aesthetics of the lake, lead to dissolved oxygen depletion, impair water taste, produce odour and form toxic algae blooms.
Phosphorus is commonly the limiting nutrient of algae growth within freshwater such as the Great Lakes. Agricultural activities, such as tillage practices, crop fertilization and pastoral grazing, can increase the rate at which phosphorus and other nutrients are delivered to the stream, particularly during hydrological events. Agricultural Best Management Practices (BMPs) are increasingly being used to mitigate the effects of agriculture on stream ecosystems by reducing nutrient losses from agricultural lands, through structural and/or managerial changes. However, knowledge of the effectiveness of BMPs at reducing ecological effects of nutrient inputs to streams during hydrological events is limited, especially when considering cumulative effects of BMPs at larger spatial scales (e.g., catchment). Therefore, this study aims to establish linkages between BMP use and nutrient loading during hydrological events and subsequent responses in ecological condition.
Objectives
Significance to the CREATE program
The outcomes of this study will contribute to improved understanding of the effectiveness of catchment scale BMP implementation at mitigating the delivery of nutrient from agricultural land into streams, and the subsequent ecological effects. More specifically, by studying multiple seasons this study will identify key times of year where current BMPs may be more or less effective in retaining nutrients on the land. This temporally based information will inform managers as to whether existing types of BMPs can effectively mitigate nutrient loadings year round or if additional BMPs are needed to address seasonal conditions. Additionally, this study will establish if stream ecological conditions benefit from reductions in nutrient loads and when in the hydrologic year those benefits are realized. Moreover, the establishment of linkages between temporal patterns and nutrient loads and stream metabolism will provide insight into whether stream ecosystems can serve as an additional barrier to nutrient loss by assimilating nutrients into instream food webs. Together these findings will enhance the understanding of how land and stream management decisions influence nutrient losses to Lake Erie, enabling improved policy and management strategies for reducing eutrophication of the lake.
Stressors Addressed: Eutrophication (nutrients), land-use practices (agriculture)
Phosphorus is commonly the limiting nutrient of algae growth within freshwater such as the Great Lakes. Agricultural activities, such as tillage practices, crop fertilization and pastoral grazing, can increase the rate at which phosphorus and other nutrients are delivered to the stream, particularly during hydrological events. Agricultural Best Management Practices (BMPs) are increasingly being used to mitigate the effects of agriculture on stream ecosystems by reducing nutrient losses from agricultural lands, through structural and/or managerial changes. However, knowledge of the effectiveness of BMPs at reducing ecological effects of nutrient inputs to streams during hydrological events is limited, especially when considering cumulative effects of BMPs at larger spatial scales (e.g., catchment). Therefore, this study aims to establish linkages between BMP use and nutrient loading during hydrological events and subsequent responses in ecological condition.
Objectives
- Compare nutrient loadings associated with hydrological events between agricultural catchments with and without BMPs.
- Quantify associations between temporal patterns in stream metabolism and nutrient loadings from hydrological events in agricultural catchments with and without BMPs.
Significance to the CREATE program
The outcomes of this study will contribute to improved understanding of the effectiveness of catchment scale BMP implementation at mitigating the delivery of nutrient from agricultural land into streams, and the subsequent ecological effects. More specifically, by studying multiple seasons this study will identify key times of year where current BMPs may be more or less effective in retaining nutrients on the land. This temporally based information will inform managers as to whether existing types of BMPs can effectively mitigate nutrient loadings year round or if additional BMPs are needed to address seasonal conditions. Additionally, this study will establish if stream ecological conditions benefit from reductions in nutrient loads and when in the hydrologic year those benefits are realized. Moreover, the establishment of linkages between temporal patterns and nutrient loads and stream metabolism will provide insight into whether stream ecosystems can serve as an additional barrier to nutrient loss by assimilating nutrients into instream food webs. Together these findings will enhance the understanding of how land and stream management decisions influence nutrient losses to Lake Erie, enabling improved policy and management strategies for reducing eutrophication of the lake.
Stressors Addressed: Eutrophication (nutrients), land-use practices (agriculture)