Characterization of River Plumes in Lake Michigan Using a Towed Multisensor Array

River plumes are dynamic environments that influence ecological processes in the nearshore regions of the Laurentian Great Lakes.  Although the role of river plumes in delivering nutrients and sediment to offshore waters has been explored in some detail, the three-dimensional dynamics of these systems are not well understood.  Here, we develop geostatistical methods for interpreting physical and biological data collected by a towed undulating sensor package, called Triaxus off three different river systems in Lake Michigan. Several geostatistical methods and visualization methods were used to identify river plumes and surrounding lake water.  Ultimately, we were able to distinguish river plumes from the surrounding lake water via clustering algorithms using water temperature and conductivity.  Once specific water masses were identified, further analyses of the lower trophic level data collected by Triaxus were conducted. Overall, we found that river water contained higher chlorophyll a concentrations and supported higher density and biomass of zooplankton than the surrounding lake water.  Our results demonstrate the utility of using towed sensor arrays to distinguish different water masses in the Great Lakes and show that river plumes can be important habitat features in large freshwater systems.