Poster Details

Abstract

Urban water systems are highly managed, especially in the semi-arid, Intermountain West. Here, humans have constructed extensive conveyance systems to support agriculture, mitigate flooding, and discharge stormwater. Despite their regional prevalence, the ecological structure and functioning of these conveyance systems remains largely unknown. To address this gap, we are comparing ecosystem structure and function (i.e. leaf decomposition) between an urban canal the Logan River in Logan, Utah. We hypothesized that leaf decomposition would be slower in the canal compared to the river because of reduced shredder biomass associated with poorer water quality. We also expected water temperature and concentrations of nutrients and metals to be higher at sites further downstream in both waterways, due to the accumulation of stressors as they flow through urban areas. To test these hypotheses, we collected water quality and freshwater invertebrates samples and measured leaf decomposition at twenty sites along the Logan River and an urban canal. Our results did not support these hypotheses. The canal showed faster leaf decomposition as the canal had a significantly lower amount of ash-free dry mass remaining in coarse-mesh litter bags compared to the river. Leaf breakdown was driven by a significantly higher biomass of shredders (Hyalella sp.) in the canal compared to the Logan River. Water chemistry data of several nutrients and metals suggest that the lower reaches of the Logan River have poorer water quality than both the canal and the upstream reaches of the river. Our results suggest that man-made waterways can retain important ecological services.