Microbial community storm dynamics signal sources of “old” stream water
Accurate prediction of water quality and quantity in a changing climate is hindered by an incomplete understanding of watershed processes, and inferential approaches to identify pathways of water to streams remain limited. Here, we demonstrate how aquatic microbial communities may serve as novel hydrologic tracers associated with known source environments recorded in bioinformatics databases. During a multiple-day storm event, as streamflow increased in volume, abundance of distinct taxonomies of microbes decreased (i.e., diluted), including groups commonly associated with freshwater. In contrast, groups that increased with streamflow (i.e., mobilized) included taxa that are associated with soil, suggesting a growing contribution of water from the hillslope. This study affirms that microbial communities provide novel information on streamflow sources and improve our understanding of hydrologic processes.