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Microbial source tracking and evaluation of best management practices for restoring degraded beaches of Lake Michigan

March 20, 2022

Attempts to mitigate shoreline microbial contamination require a thorough understanding of pollutant sources, which often requires multiple years of data collection (e.g., point/nonpoint) and the interacting factors that influence water quality. Because restoration efforts can alter shoreline or beach morphology, revisiting source inputs is often necessary. Microbial source tracking (MST) using source-specific molecular markers, genomic community analyses, and physical modeling was used to identify contamination sources along three Lake Michigan beaches of the Laurentian Great Lakes with historically high fecal indicator bacteria (FIB, E. coli) concentrations. Genetic markers for human (Bacteroides HF183) and mixed gull species (Catellicoccus marimammalium) fecal sources were tested from water and sediment. Gene sequencing (16S rRNA) was used to identify similarities in bacterial communities in nearshore water, river inputs, sand, sediment, and groundwater. Synoptic surveys of water exchange were conducted to determine nearshore-offshore interactions of FIB. In addition to these MST studies, best management practices to mitigate FIB, including gull deterrence, slope grading, wetland establishment, and shoreline plantings, were reviewed for their effectiveness at reducing FIB concentrations over time. Using multiple tools for MST helped identify primary and secondary sources of FIB (gulls, stormwater inputs) and the physical processes that exacerbate FIB concentrations (onshore currents, limited circulation). Management actions were successful in the short-term at reducing FIB, but scope of success was temporally limited, with FIB concentrations often rebounding. Results highlight the usefulness of MST to inform best management practices and the need for a sustained adaptive approach that adjusts for changes in the coastal system.

Publication Year 2022
Title Microbial source tracking and evaluation of best management practices for restoring degraded beaches of Lake Michigan
DOI 10.1016/j.jglr.2022.01.009
Authors Meredith B. Nevers, Paul M. Buszka, Muruleedhara Byappanahalli, Travis Cole, Steven R. Corsi, P. Ryan Jackson, Julie L. Kinzelman, Cindy H Nakatsu, Mantha S. Phanikumar
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Great Lakes Research
Index ID 70229973
Record Source USGS Publications Warehouse
USGS Organization Great Lakes Science Center