"Brine-induced mortality of non-indigenous species in ballast water" by Johanna Bradie

Date of Award

2009

Publication Type

Master Thesis

Degree Name

M.Sc.

Department

Great Lakes Institute for Environmental Research

Keywords

Toxicology.

Supervisor

MacIsaac, Hugh (GLIER)

Rights

info:eu-repo/semantics/openAccess

Abstract

Transoceanic vessels entering the Great Lakes are required to undergo ballast water exchange to reduce the risk of transporting non-indigenous species. Ballast water exchange effectively reduces invertebrate density and richness in ballast; however, an alternative treatment is required for non-compliant ships. Sodium chloride brine was proposed to treat residual and incompletely-exchanged ballast water. Laboratory experiments were conducted to determine the minimum brine treatment to exterminate >95% of ballast water taxa. Invertebrate communities were exposed to a range of brine concentrations (15ppt to 115ppt) until complete mortality was reached. Biological evidence supports a one-hour exposure to 115ppt brine to treat ballast water. This treatment is broadly effective (>99.9%) regardless of treatment temperature, taxonomic group, or species' habitat salinity. A median of 0.00% (range 0.00-5.33) of individuals in ballast are expected to survive treatment, and the expected number of individuals released is within Canadian discharge standards. Before implementation, ship-scale trials are required.

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