Freshwater wrack along Great Lakes coasts harbors Escherichia coli: Potential for bacterial transfer between watershed environments

Journal of Great Lakes Research
By: , and 

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Abstract

We investigated the occurrence, persistence, and growth potential of Escherichia coli associated with freshwater organic debris (i.e., wrack) frequently deposited along shorelines (shoreline wrack), inputs from rivers (river CPOM), and parking lot runoffs (urban litter). Samples were collected from 9 Great Lakes beaches, 3 creeks, and 4 beach parking lots. Shoreline wrack samples were mainly composed of wood chips, straw, sticks, leaf litter, seeds, feathers, and mussel shells; creek and parking lot samples included dry grass, straw, seeds, wood chips, leaf/pine needle litter; soil particles were present in parking lot samples only. E. coli concentrations (most probable number, MPN) were highly variable in all sample types: shoreline wrack frequently reached 105/g dry weight (dw), river CPOM ranged from 81 to 7,916/g dw, and urban litter ranged from 0.5 to 24,952/g dw. Sequential rinsing studies showed that 61–87% of E. coli concentrations were detected in the first wash of shoreline wrack, with declining concentrations associated with 4–8 subsequent washings; viable counts were still detected even after 8 washes. E. coli grew readily in shoreline wrack and river CPOM incubated at 35 °C. At 30°C, growth was only detected in river CPOM and not in shoreline wrack or urban litter, but the bacteria persisted for at least 16 days. In summary, freshwater wrack is an understudied component of the beach ecosystem that harbors E. coli and thus likely influences estimations of water quality and the microbial community in the nearshore as a result of transfer between environments.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Freshwater wrack along Great Lakes coasts harbors Escherichia coli: Potential for bacterial transfer between watershed environments
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2016.04.011
Volume 42
Issue 4
Year Published 2016
Language English
Publisher International Association for Great Lakes Research
Contributing office(s) Great Lakes Science Center
Description 8 p.
First page 760
Last page 767
Country Canada, United States
State Illinois, Indiana, Ontario