Using turbidity measurements to estimate phosphorus and sediment flux in a Great Lakes Coastal Marsh, in Ohio

Great Lakes coastal marshes have the potential to filter water coming off of the landscape and remove sediments and nutrients before they reach the lakes. However, this ability has largely been neutralized as vast areas of coastal wetlands have been isolated behind dikes; while at the same time the Great Lakes continue to suffer from excess phosphorus loading. In this study we used high-frequency measurements of discharge and turbidity to estimate sediment and phosphorus retention in a formerly diked coastal wetland. We found sediment and phosphorus retention to be episodic and highly related to fluctuations in water level. Low water levels in Lake Erie in late 2012 resulted in low retention in the wetland, but as water levels rose in the first half of 2013 sediment and phosphorus retention increased. Overall, the reconnected wetland was a sink for both total phosphorus and suspended sediment, and locally reduced phosphorus loading rates to Lake Erie.