Do Ballast Water Management Systems Reduce Phytoplankton Introductions to Canadian Waters?

Abstract

Global coastal aquatic ecosystems are negatively impacted by the introduction of harmful aquatic species through the discharge of ships’ ballast water. To reduce discharges of harmful aquatic organisms and pathogens, such as toxic phytoplankton species, ships are now transitioning to the use of ballast water management systems (BWMS) instead of ballast water exchange (BWE). This study examines the abundance and diversity of phytoplankton in ballast water managed by BWMS (or a combination of both BWE + BWMS) in comparison to those in ballast water managed by BWE alone (collected from ships arriving to Canada’s Pacific coast in 2017–2018 and 2008, respectively). The abundance and diversity of phytoplankton species were also examined in relation to key variables such as ballast water salinity and ballast water age. Total abundance of phytoplankton was significantly lower in preserved samples managed by either a BWMS or BWE + BWMS compared to BWE alone. Abundances in preserved samples were higher than observed in fresh (unpreserved) samples at the time of collection, with all samples managed by a BWMS meeting international limits for the number of viable organisms ≥10 and <50 μm in minimum dimension (based on six 1-mL live counts). While there was no apparent influence of factors such as treatment type [e.g., ultraviolet (UV) or chlorine], presence of filtration, ballast water salinity, ballast water age, nor location of last ballast water uptake on phytoplankton abundances in preserved samples, power to detect differences may be limited by sample size. Ballast water managed by BWMS also tended to have lower abundances of harmful phytoplankton species, although the difference was not statistically significant – additional research into the community composition of live cells in fresh samples could be valuable to discriminate the risk associated with phytoplankton surviving ballast water treatment.

Examining the performance of three ballast water compliance monitoring devices for quantifying live organisms in both regulated size classes (≥50 μm and ≥10–<50 μm)

“…In addition, a small volume sample collection device integrated into the large volume sample collection device was used to collect 20–30 L of whole water into a carboy for analysis of the ≥10–<50 μm size class. Carboys were gently overturned at least five times to mix their content and the water was subsequently split for analysis by B-QUA (1 × 1 L sample) and epifluorescence microscopy (1 L sample) ( Casas-Monroy and Bailey, 2021 ; Casas-Monroy et al ., 2022 ). All sample bottles were kept in a dark, insulated container with ice packs wrapped in bubble wrap (samples kept near or below ambient ballast water temperature) and analyzed within 3–4 h.…”

“…Chlorophyceae , Bacillariophyceae , Dinophyceae , etc.). Only intact cells with clearly visible cell content were assessed (see Casas-Monroy and Bailey, 2021 for details on sample collection and processing).…”

Managing risk of non‐indigenous species establishment associated with ballast water discharges from ships with bypassed or inoperable ballast water management systems

“…Organism discharge concentrations were dependent on management scenario. A fully functioning BWMS was assumed to discharge <10 live (viable) individuals m −3 and ml −1 for zooplankton and phytoplankton, respectively, with actual concentrations estimated from successful treatment applications observed in field studies [Poisson distributions with mean 1.81 live zooplankton organisms m −3 (Bailey et al, 2022) and 1.38 live phytoplankton cells ml −1 (Casas‐Monroy & Bailey, 2021)]. Partial BWMS concentrations were calculated by applying a 95% reduction to modelled uptake concentrations, matching reductions observed in limited field data (see ‘ Model sensitivity ’) while not being so effective that most voyages became compliant.…”

Modification of Ballast Filtering Device on John Lie Training Ship to Prevent Marine Pollution

“…This can also have an impact on the imbalance of marine ecosystems and adversely affect the marine life development (Bailey et al, 2022). The impact of the foreign species development at sea by the IMO is considered more difficult to overcome than the impact of pollution due to oil spills and has become a global problem that requires more serious attention from the entire world maritime community (Bradie et al, 2023;Casas-Monroy & Bailey, 2021;Čulin & Mustać, 2015).…”