A DAY IN THE LIFE OF A RIVER: LAGRANGIAN PROFILING OF RIVER METABOLISM
River ecosystem processes vary in time and space. The reference frame employed to investigate ecosystem dynamics constrains what can be learned. Over 60 years of Eulerian (i.e., fixed station) measurements of stream metabolism have yielded enormous insights about the controls and constraints on primary production and respiration through river networks. With this work, we extend metabolism measurements to a Lagrangian reference frame, wherein spatial variation in ecosystem processes is of particular interest. Using a citizen science approach, we obtained many longitudinal temperature and dissolved oxygen (DO) profiles from multiple spring-fed rivers over a single day. These ca. 5 km profiles are analyzed for spatial patterns of primary production and respiration, and the results contrasted to contemporaneous fixed-station measurements. The profiles reveal substantial spatial variation in the rates of DO production and depletion, from which spatially dis-aggregated metabolism estimates were obtained. These rates were entirely consistent with reach-scale estimates from fixed-point DO time series, but reveal considerable within-reach heterogeneity. Where spatial variation in metabolism is expected to be important, as in river networks and heterogeneous channels, this Lagrangian approach is simple and informative.
Matthew Cohen (Primary Presenter/Author), University of Florida, firstname.lastname@example.org;
Robert Hensley (Co-Presenter/Co-Author), University of Florida, email@example.com;
Lauren Devito (Co-Presenter/Co-Author), University of Florida, firstname.lastname@example.org;