Natural-born Killers—anti-fouling coating systems and their mixed effects on the marine environment

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine, by Mr. Charles (Bud) Darr, U.S. Coast Guard Office of Maritime and International Law.


Like so many issues related to environmental protection, balancing the benefits of a particular protective measure against the potential harm is a prime consideration. For example, anti-fouling hull coating systems can provide substantial environmental benefits, but an effective coating system can also have an unfortunate negative impact on the marine environment. In other words, what happens when the natural-born killers are too good at killing?

Positive Effects of Anti-fouling Coating Systems
As a ship’s hull becomes fouled with biological matter, the resulting surface friction causes a significant increase in the power required to maintain speed. The additional power output results in increased fuel consumption, which adds cost. As power output increases, the air pollution emissions from a shipboard propulsion system also increase.

Possible Environmental Harm
Among the environmental harm caused by certain anti-fouling coating systems are documented mutations in invertebrate species, long-term heavy metal deposition, effects on marine mammals, and dangers to human health and welfare.

Although more research remains to be done, there is a growing belief that the top of the food chain, including these mammal vertebrate species, is substantially affected by exposure to these biocides.

Ongoing Efforts
At present, the principal substitutes are copper-based coating systems. However, copper is far from a perfect solution because it is also associated with negative environmental effects, though not believed to be as serious as those related to biocides.

Although there are some less toxic alternative biocides under consideration, some of the most promising alternatives may be those that approach the problem by inhibiting adherence of the species to the hull rather than killing the species directly.


For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.

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Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.