Exploring potential spatial-temporal links between fluvial geomorphology and nutrient-periphyton dynamics in streams using simulation models

Understanding stream ecosystem processes necessitates an awareness of not only the physical, chemical, and biological systems, but also how these separate systems interact with each other. Using a nutrient retention and periphyton growth model coupled to a dynamic geomorphic template, we explore the potential role of channel shape, slope, and sediment texture on downstream nutrient retention, and attempt to determine if physical changes alone can drive or influence changes in nutrient-periphyton dynamics. The overall model results suggest there is a strong potential control of both nutrient retention and periphyton biomass by channel morphology. For example, with constant biochemical process rates, geomorphic variations alone could alter spatial distribution of nutrient retention over a 4-km study reach by between 11 percent and 52 percent. These results suggest channel geomorphology has a potentially strong influence on both nutrient retention and basal food sources in streams.