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

Journal of Great Lakes Research
By: , and 



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.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Microbial source tracking and evaluation of best management practices for restoring degraded beaches of Lake Michigan
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2022.01.009
Volume 48
Issue 2
Year Published 2022
Language English
Publisher Elsevier
Contributing office(s) Great Lakes Science Center
Description 14 p.
First page 441
Last page 454
Country United States
State Illinois, Wisconsin
City Chicago, Racine
Other Geospatial Jeorse Park Beach, Lake Michigan, North Beach, 63rd Street Beach
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