Geographical Gaps Limit Ballast Water Research

The US Coast Guard’s Office of Commercial Vessel Compliance recently released its U.S. Port State Control Annual Report for 2024 highlighting a 200% increase in untreated ballast water discharges compared to 2023.

With this result, there’s still a risk of invasive species arriving in ballast water. And a review of research into the organisms found in ballast water published in March highlights just how limited current knowledge is.

The study found that 53.5% of the sampling effort of in-situ ballast water has been concentrated in North America, as determined from a review of 2,088 studies published between 1932 and 2022.

For both number of publications and sampling effort, approximately 85% of data is from the northern hemisphere.

Only 12% of publications documenting plankton organisms sampled in ballast water were from the southern hemisphere, and no study reported analyses of benthic communities in ballast tanks outside of North America and Europe.

Without ballast water management, a single discharge could release billions of organisms. However, ships with the greatest quantity of ballast water discharge aren’t necessarily the greatest environmental risk, as the diversity and viability of organisms varies with source region, transit route and season.

The study authors highlight that this has important ramifications for testing the efficacy of ballast water treatment systems. “Ballast water treatment technologies being used now to meet discharge standards, such as chlorination, ultraviolet radiation, and ozonation (often in combination with filtration), are sensitive to differences in temperature and multiple water quality parameters which vary among global regions. Thus, measures of performance or compliance in one global region may not adequately predict or serve as a proxy for different regions.”

The conditions used for type approval testing represent a very limited range of real-world conditions. Thus, it remains critical to address current gaps with in-situ analyses going forward, they say.

The US Coast Guard is also calling for action after observing an overall increase of 6% in ballast water related deficiencies compared to 2023. It is asking vessel operators to prioritize proper operation of ballast water management systems as designed, along with prioritizing maintenance and proactive inspections of components to address vulnerabilities before they result in violations.

“Given the increase in deficiencies, the service anticipates focusing heavily on ballast water in the near term to mitigate non-compliance and support improved system performance across the fleet. As we move into 2025, the Coast Guard remains committed to working with industry stakeholders to strengthen compliance efforts and ensure the continued protection of our marine environment.”