First evaluation of ballast water management systems on operational ships for minimizing introductions of nonindigenous zooplankton
Bailey, S., T. Brydges, O. Casas-Monroy, J. Kydd, R. Linley, R. Rozon, AND J. Darling. First evaluation of ballast water management systems on operational ships for minimizing introductions of nonindigenous zooplankton. MARINE POLLUTION BULLETIN. Elsevier Science Ltd, New York, NY, 182:113947, (2022). https://doi.org/10.1016/j.marpolbul.2022.113947
This manuscript describes tests of ballast water management systems installed on board ships entering Canadian ports, to determine if those systems are meeting international numerical discharge standards for live zooplankton in ballast water. The manuscript also includes overall assessments of biodiversity present in treated ballast water, based on both morphological and DNA-based identification. The study provides the first look at the efficacy of installed management systems, assesses likely reasons for failures to meet regulatory standards, and offers a general description of the diversity of organisms being transferred with treated ballast water. These results will assist with assessing risks associated with ballast water in the current and future regulatory climate, and in determining the degree to which regulation have reduced that risk.
Ballast water is a leading pathway for the global introduction of aquatic nonindigenous species. Most international ships are expected to install ballast water management systems (BWMS) by 2024 to treat ballast water before release. This study examines if ballast water discharges managed by BWMS are meeting standards for organisms ≥50 μm in minimum dimension (i.e., <10 organisms per m3; typically zooplankton). Representative samples of ballast water were collected from 29 ships (using 14 different BWMS) arriving to Canada during 2017–2018. Fourteen samples (48 %) had zooplankton concentrations clearly exceeding the standard (ranging from 18 to 3822 organisms per m3). Nonetheless, compared to earlier management strategies, BWMS appear to reduce the frequency of high-risk introduction events. BWMS filter mesh size was an important predictor of zooplankton concentration following treatment. Greater rates of compliance may be achieved as ship crews gain experience with operation and maintenance of BWMS.
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