title: Influence of wave action on the partitioning and transport of unattached and floc-associated bacteria in fresh water.
abstract: The dynamic interaction of bacteria within bed sediment and suspended sediment (i.e., floc) in a wave-dominated beach environment was assessed using a laboratory wave flume. The influence of shear stress (wave energy) on bacterial concentrations and on the partitioning and transport of unattached and floc-associated bacteria was investigated. The study showed that increasing wave energy (0.60 and 5.35 N/s) resulted in a 0.5 to 1.5 log increase in unattached cells of the test bacterium Pseudomonas sp. strain CTO7::gfp-2 in the water column. There was a positive correlation between the bacterial concentrations in water and the total suspended solids, with the latter increasing from values of near 0 to up to 200 mg/L over the same wave energy increase. The median equivalent spherical diameter of flocs in suspension also increased by an order of magnitude in all experimental trials. Under both low (0.60 N/s) and high (5.35 N/s) energy regime, bacteria were shown to preferentially associate with flocs upon cessation of wave activity. The results suggest that collecting water samples during periods of low wave action for the purpose of monitoring the microbiological quality of water may underestimate bacterial concentrations partly because of an inability to account for the effect of shear stress on the erosion and mobilization of bacteria from bed sediment to the water column. This highlights the need to develop a more comprehensive beach analysis strategy that not only addresses presently uncharacterized shores and sediments but also recognizes the importance of eroded flocs as a vector for the transport of bacteria in aquatic environments.
authors.affiliation: a Ryerson University, Department of Chemistry and Biology, Toronto, ON M5B 2K3, Canada.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sousa
authors.affiliation: a Ryerson University, Department of Chemistry and Biology, Toronto, ON M5B 2K3, Canada.|b Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6, Canada.
authors.forename: Ian G
authors.initials: IG
authors.lastname: Droppo
authors.affiliation: c Queen's University, Department of Chemical Engineering, Kingston, ON K7L 3N6, Canada.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Liss
authors.affiliation: d McMaster University, School of Geography and Earth Sciences, Hamilton, ON L8S 4K1, Canada.
authors.forename: Lesley
authors.initials: L
authors.lastname: Warren
authors.affiliation: a Ryerson University, Department of Chemistry and Biology, Toronto, ON M5B 2K3, Canada.|e Stellenbosch University, Department of Microbiology, Private Bag X1, Matieland, 7602, South Africa.
authors.forename: Gideon
authors.initials: G
authors.lastname: Wolfaardt
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D058491:Bacterial Load; D018441:Biofilms; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology; D013314:Stress, Mechanical
keywords: action des vagues; bacteria; bacterial mobilization; bactéries; bactéries de sédiment; floc; floculat; mobilisation bactérienne; sediment bacteria; wave action