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Spatial and Temporal Water Quality Patterns in Open-Water Lake Michigan from the 2015 CSMI
Citation:
Trebitz, A., A. Cotter, A. Opseth, A. Scofield, AND J. Hoffman. Spatial and Temporal Water Quality Patterns in Open-Water Lake Michigan from the 2015 CSMI. To be Presented at International Association for Great Lakes Research, Detroit, MI, May 15 - 19, 2017.
Impact/Purpose:
not applicable
Description:
Water quality patterns in the Laurentian Great Lakes broadly reflect climate, surficial geography, and landuse but are also shaped by limnological and biological processes. Open-water sampling conducted as part of the 2015 Lake Michigan interagency coordinated science and monitoring initiative (CSMI) at 3 depths along 8 transects over 3 time periods provides an opportunity to examine water quality patterns over large spatial scales and hydrologically active time periods. Sampling stations were unstratified but showing surface warming in May, and stratified with elevated metalimnetic nutrients and chlorophyll at deeper stations in July and September. Significant spatial patterns (e.g., north vs south, shallow vs. deep) were observed in in some but not all sampling periods, but patterns in CHLA were not necessarily concordant with nutrients. Consistent with recent trends, we find that open waters remain generally oligotrophic in both TP and CHLA. Biological composition changes may be driving a temporal offset between nutrient maxima during spring isothermal conditions and CHL maxima during summer-stratification.