Nutrient and microbial community dynamics in agriculturally-intensive watersheds impacting Lake Erie

Session: Nutrient Sources, Transport, and Internal Cycling (1)

Nick Falk, University of Windsor GLIER, [email protected]
Ken Drouillard, University of Windsor, Great Lakes Institute for Environmental Research, [email protected]
Chris Weisener, University of Windsor, [email protected]

Abstract

Tributary bed sediments can be release vectors of legacy phosphorous (P) within agricultural catchments of the Great Lakes, even after point/non-point source abatement. However, monitoring frameworks generally focus only on P-species in the water column, potentially missing the influence of phosphorous flux in benthic settings. Further, microbial community dynamics related to nutrient transformations in sediments has not been accounted for, despite the tremendous control they exert on hyporheic redox state. To address this research gap, a study was initiated through April-July 2018 within Big Creek, ON; a tributary of Lake St. Clair. Bed sediment samples from an upstream region of the agricultural catchment were collected and analyzed for bioavailable P buffering capacity through zero-equilibrium phosphorous concentration incubations and coupled with microbial community analysis via DNA-extraction and water chemistry parameters. In tandem, suspended particulate load samples were collected via sediment traps to assess microbial transport and resuspension between sampling points. Results suggest fine scale (<1 km) variabilities in P buffering capacity within the sampling region related to creek morphology, as well as spatial/temporal relationships between the microbial community and bioavailable P flux. Future work will seek to correlate sources/timing of sediment phosphorous release with in-situ microbial gene expression via metatranscriptomic analysis.

Twitter handle of presenter
@falkemup