title: Chlorine dioxide as a treatment for ballast water to control invasive species: shipboard testing.
abstract: The efficacy of chlorine dioxide (ClO2) in eliminating organisms present in estuarine ballast water of a containership was determined under actual operating conditions by comparing the survival of planktonic communities present in waters of treated and control ballast tanks. Sampling was via ballast-tank hatches. The treatment (5 mg L(-1)ClO2 without pre-filtration) delivered by a prototype ClO2-generating system was generally effective against planktonic assemblages, although bacterial communities rebounded after a few days. Regardless of temperature, ClO2 was very effective against phytoplankton; the effect was immediate, without resurgence. Some zooplankters in the ≥ 50-μm fraction may survive the biocide, especially those able to find refuge within a protective coating (e.g., cysts, resting eggs, and shells) or in sediment. In order to boost efficacy, a pre-filtration step is recommended (now installed as standard equipment) to lower the intake of the ≥ 50-μm fraction and lessen the challenge posed by this size class.
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI 02882, USA. Electronic address: lmaranda@mail.uri.edu.
authors.forename: Lucie
authors.initials: L
authors.lastname: Maranda
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI 02882, USA.
authors.forename: Annie M
authors.initials: AM
authors.lastname: Cox
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI 02882, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Campbell
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI 02882, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Smith
mesh_terms: D000818:Animals; D001419:Bacteria; D017606:Chlorine Compounds; D004202:Disinfectants; D058865:Introduced Species; D010087:Oxides; D010933:Plankton / Q000254:growth & development*; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology; D012767:Ships
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide
keywords: Ballast water; Biocide; Chlorine dioxide; ClO(2); Invasive species; Shipping