title: The green alga, Cladophora, promotes Escherichia coli growth and contamination of recreational waters in Lake Michigan.
abstract: A linkage between Cladophora mats and exceedances of recreational water quality criteria has been suggested, but not directly studied. This study investigates the spatial and temporal association between Escherichia coli concentrations within and near Cladophora mats at two northwestern Lake Michigan beaches in Door County, Wisconsin. Escherichia coli concentrations in water underlying mats were significantly greater than surrounding water (p < 0.001). Below mat E. coli increased as the stranded mats persisted at the beach swash zone. Water adjacent to Cladophora mats had lower E. coli concentrations, but surpassed EPA swimming criteria the majority of sampling days. A significant positive association was found between E. coli concentrations attached to Cladophora and in underlying water (p < 0.001). The attached E. coli likely acted as a reservoir for populating water underlying the mat. Fecal bacterial pathogens, however, could not be detected by microbiological culture methods either attached to mat biomass or in underlying water. Removal of Cladophora mats from beach areas may improve aesthetic and microbial water quality at affected beaches. These associations and potential natural growth of E. coli in bathing waters call into question the efficacy of using E. coli as a recreational water quality indicator of fecal contaminations.
authors.affiliation: Dep. of Biology and Microbiology, Univ. of Wisconsin-Oshkosh, 800 Algoma Blvd., Oshkosh, WI 54901, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Vanden Heuvel
authors.forename: Colleen
authors.initials: C
authors.lastname: McDermott
authors.forename: Robert
authors.initials: R
authors.lastname: Pillsbury
authors.forename: Todd
authors.initials: T
authors.lastname: Sandrin
authors.forename: Julie
authors.initials: J
authors.lastname: Kinzelman
authors.forename: John
authors.initials: J
authors.lastname: Ferguson
authors.forename: Michael
authors.initials: M
authors.lastname: Sadowsky
authors.forename: Muruleedhara
authors.initials: M
authors.lastname: Byappanahalli
authors.forename: Richard
authors.initials: R
authors.lastname: Whitman
authors.forename: Gregory T
authors.initials: GT
authors.lastname: Kleinheinz
mesh_terms: D001493:Bathing Beaches; D000460:Chlorophyta / Q000502:physiology*; D004926:Escherichia coli / Q000254:growth & development*; D005618:Fresh Water / Q000382:microbiology*; D014871:Water Microbiology / Q000592:standards*; D014876:Water Pollution; D014922:Wisconsin