Scholarly Commons

Nutrient Composition and Sediment Size in Stream Sediments

Precision conservation is the use of geospatial analysis of high-resolution datasets to determine the location where restoration will be the most effective based on elements like stream location, watershed size, and neighboring land use. For four years, Susquehanna University has worked with the Chesapeake Conservancy to study the effects of stream restoration throughout nine different watersheds in Centre, Montour, Union, and Northumberland counties. Sites are monitored before and after stream restoration has been implemented to determine the effects of restoration and best management practices on factors such as species diversity, fish populations, water quality, mean grain size of sediments, and nutrient concentrations in stream sediment. At 31 different sites, a one hundred-meter reach is electroshocked for fish, and five sediment samples are taken from a pool, riffle, eddy, a run from pool to a riffle, and a run from a riffle to a pool. The sediment samples were analyzed for grain size and nutrient concentrations, including ammonia, nitrate, and phosphate. Stream restoration should help improve stream quality by reducing erosion and the amount of fine sediments entering the stream. It was found that as mean grain size of sediments decreased, nitrate and ammonia concentrations increased, while phosphate concentrations showed no significant correlations to grain size. Increasing amounts of clay, silt, and ammonia in sediment samples also correlated to heavily agriculturally impacted streams. Also, fish populations decreased as nutrient concentrations increased, with a significant correlation to nitrate. By studying nutrient concentrations and their correlation to mean grain size, we hope to demonstrate that best management practices can improve both fish and macroinvertebrate habitat and reduce the potential nutrient storage in the stream channel sediments.