Fungus in hull paint may solve barnacle problem

February 28, 2007 Biofouling of marine organisms on ship hulls has been a global problem since man crafted the first boat. These days, many marine enterprises suffer the problem and the cost of reducing it, in aquaculture, offshore industries and harbours. In shipping alone, marine biofouling and its most significant organism, the barnacle, increase drag, adversely affect fuel consumption, increase pollution (via the workload on the machinery and downtime due to dry-docking. The annual global cost of cleaning alone is in the billions of dollars. Toxic paints are the most prevalent current anti-fouling strategy but they cause severe environmental disturbances due to the emission of toxic substances into the marine environment. Currently used toxic paints based on Tributyl tin oxide (TBT) are the first target as they generate unwanted effects at non-target organisms and will be banned by 2010, but this ban may be followed by the prohibition of other substances in marine paints. Now a new type of paint has been developed which uses an extract from the microscopic fungus Streptomyces avermitilis to poison barnacles. The fungus lives in the ocean and is extremely poisonous to acorn barnacles and other crustaceans, a feature based on the environmentally friendly defense of the fungus against being eaten. A new study from Goteborg University in Sweden has found that when this fungus is added to paint for ship hulls, the surface remains entirely free from barnacles. As little as a 0.1-percent mixture of pure fungal extract in paint is sufficient to affect the nervous system of barnacles and prevent any growth and the fungal extract is toxic only as long as the paint is on a painted surface. When the paint is dissolved in sea water, the activation of the poison appears not to take place, making the paint apparently harmless to organisms in the open sea.

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