title: Influence of CuSO4and chelated copper algaecide exposures on biodegradation of microcystin-LR.
abstract: Copper exposures from algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated. Microcystis aeruginosa was exposed to four concentrations (0-5.0 mg Cu L-1) of three copper-algaecide formulations, and rates and extents of MCLR degradation were measured. In untreated controls and following exposures of 0.1, 0.5, and 1.0 mg Cu L-1, MCLR concentrations decreased at a rate of ∼41-53 μg MCLR/L d-1. Following exposure to 5.0 mg Cu L-1MCLR degradation rates decreased an order of magnitude to ∼3-7 μg MCLR/L d-1. Bacterial diversity decreased following copper-exposures greater than 0.1 mg Cu L-1for all formulations. Relative abundance of certain groups of MC-degrading bacteria identified in treatments increased with increasing copper concentration, suggesting they may be less sensitive to copper exposures than other, MCLR and non MC-degrading heterotrophic bacteria present in the assemblage. Results from this study revealed that copper concentration can influence degradation rates of MCLR, however this influence was not significant within copper concentrations currently registered for use (≤1.0 mg Cu L-1) of the tested algaecides. Copper formulation did not significantly alter degradation rates or bacterial composition. These data augment our understanding of the influences of copper algaecide-exposures on MCLR degradation, and can be used to inform more accurate risk evaluations and use of copper-algaecides for management of MCLR-producing cyanobacteria.
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA. Electronic address: kiwinsk@g.clemson.edu.
authors.forename: Kyla J
authors.initials: KJ
authors.lastname: Iwinski
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Rodgers
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: Ciera M
authors.initials: CM
authors.lastname: Kinley
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: Maas
authors.initials: M
authors.lastname: Hendrikse
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: Alyssa J
authors.initials: AJ
authors.lastname: Calomeni
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McQueen
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, 29634-0001, USA.
authors.forename: Tyler D
authors.initials: TD
authors.lastname: Geer
authors.affiliation: Contango Strategies Ltd., 410 Downey Road, Saskatoon, SK, S7N 4N1, Canada.
authors.forename: Jenny
authors.initials: J
authors.lastname: Liang
authors.affiliation: Contango Strategies Ltd., 410 Downey Road, Saskatoon, SK, S7N 4N1, Canada.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Friesen
authors.affiliation: Contango Strategies Ltd., 410 Downey Road, Saskatoon, SK, S7N 4N1, Canada.
authors.forename: Monique
authors.initials: M
authors.lastname: Haakensen
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects; D003300:Copper / Q000633:toxicity*; D019327:Copper Sulfate / Q000633:toxicity*; D006540:Herbicides / Q000633:toxicity*; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism*; D046931:Microcystis / Q000187:drug effects* / Q000378:metabolism
chemical_list: D006540:Herbicides; D008387:Marine Toxins; D052998:Microcystins; D003300:Copper; C057862:cyanoginosin LR; D019327:Copper Sulfate
keywords: Algaecides; Copper; Microcystin; Microcystin-degrading bacteria; Microcystis aeruginosa