Combining ballast water treatment and ballast water exchange: Reducing colonization pressure and propagule pressure of phytoplankton organisms

Abstract

The International Maritime Organization (IMO) will enforce a new abundance-based performance standard for ballast water in September, 2017. Strong oxidants, like chlorine, have been proposed as a method for achieving this standard. However chlorine treatment of ballast water can produce hazardous trihalomethanes. We assessed maximum trihalomethane production from one chlorine dose for three types of ballast water (fresh, brackish and marine) and three levels of total organic carbon (TOC) concentration (natural, filtered, enhanced). While the current standard test considers a five day voyage, there is a high possibility of shorter trips and sudden change of plans that will release treated waters in the environment. Water source and TOC significantly affected trihalomethane production, with the highest amounts generated in brackish waters and enhanced TOC concentration. The concentration of brominated trihalomethanes increased from background levels and was highest in brackish water, followed by marine and fresh water.

Ballast Water Exchange Plus Treatment Lowers Species Invasion Rate in Freshwater Ecosystems

“…Land-based and shipboard research on exchange plus treatment determined that the combined approach may benefit freshwater ecosystems by reducing the abundance of high-risk freshwater and euryhaline organisms in discharged ballast water. , Additionally, exchange plus treatment may provide greater reduction in the total abundance and diversity of certain taxonomic groups compared to treatment alone. , This past work focused on specific cause-and-effect relationships without assessing the linked, system-wide effects of a management measure. Estimating the species establishment rate under different ballast water management measures is a useful approach to evaluate the costs and benefits of management measures at scales suitable for decision-making.…”

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

“…Briski et al (2015) also found a larger effect of BWE + BWMS on community composition of treated ballast water samples, owing to their targeted research objective to examine voyages having freshwater ballast prior to management. Shipboard studies conducted by Paolucci et al (2015Paolucci et al ( , 2017 similarly found that treatment, alone or combined with exchange, lowered total abundance of viable microplankton (≥10 and <50 µm size class). While Paolucci et al (2015Paolucci et al ( , 2017 found only the combined management method met the D-2 standard, it should be noted that chlorine was applied directly to ballast tanks from the ship's deck without a primary filtration step, so results are not directly comparable with those of BWMS.…”

Environmental DNA Metabarcoding: A Promising Tool for Ballast Water Monitoring

“…As BW exchange will be soon phased out as a management method and replaced by the use of BW treatment systems to meet the D2 standard, 81 the development of methods to assess the efficiency of BW treatment systems on communities is logically gaining more attention. 8,82,83 The use of eDNA metabarcoding has been proposed as a major tool to characterize the difference between communities 21,82,84 and tested on microorganisms. 82 Here, although we had only 2 vessels with treated BW, we also detected an important effect of the BW treatment system as failure with DNA extraction and/or amplification was only observed for vessels with treated BW or for vessel with exchanged BW sampled at the sounding pipe.…”