Comparison of Heterotrophic Activity in Forested Streams Originating from Wetland and Agricultural Tile Drainage Sources
Abstract
Agricultural development of lands in Southern Ontario, Canada, have resulted in many headwater streams being sourced by agricultural tile drains instead of wetlands. Tile drainage inputs can influence stream conditions (i.e., temperature, hydrology, and water chemistry) that are important drivers of ecological function. To assess the influence of agricultural tile drainage inputs on stream ecosystem function, I compared heterotrophic activity (i.e., organic matter breakdown and benthic respiration) in forested streams originating from wetland and agricultural tile drainage sources over four seasons. I found a reduction in heterotrophic activity in the tile-sourced stream, particularly in the summer, that appeared to be due to reduced stream temperatures from influxes of groundwater. Reduced heterotrophic activity was also evident in downstream network segments. My findings suggest there may be a widespread reduction in heterotrophic activity in streams across agricultural regions where tile drainage is prevalent.