December 2004
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MUSSEL MIMIC TO PREVENT MARINE FOULINGMarine fouling is a perennial problem for boats, ports and anything kept in the sea for a period of time. The sea is teeming with the tiny larvae of marine organisms, that swim around until they find somewhere to settle and grow. Smooth surfaces are particularly attractive to many of these creatures, and are quickly encrusted. This can slow ships, block pipes and speed corrosion.
The traditional solution has been anti-fouling paints, containing heavy metals such as copper and tin, and herbicides. These paints contribute to marine pollution, and harm a variety of sea life, including dolphins and whales, which accumulate heavy metals in their livers. CRC Reef associate student Mr Andrew Scardino from James Cook University may have discovered an environmentally friendly alternative to chemical anti-foulant paints – among some old shells on the beach. Andrew was intrigued by the fact that the shells of the blue mussel, Mytilus galloprovincialis, always seem to be clean and shiny, without any of the marine fouling that affects other shells, ships and coastal infrastructure. He decided to test whether the natural texture of the blue mussel shell prevented other marine organisms from latching on. The outer surface of the blue mussel shell has tiny ripples, only a few thousandths of a millimetre wide. Using dental impression gel, Andrew made moulds of blue mussel shells, and created resin copies, which he left in the sea to test for fouling. The resin copies of the mussel shell resisted fouling for 6-8 weeks. Under a microscope, Andrew saw that after this time the tiny ripples in the mould had been filled by a ‘biofilm’ of bacteria, which then made the surface smooth enough for larger organisms to settle. Andrew suspects that the mussel’s natural defence from fouling may rely on a mixture of texture and a protein coating on the shell. He is now testing shells which have had the protein coating changed, to find out whether the protein is responsible for improving anti-fouling. Mimicking the natural anti-fouling properties of the blue mussel, as well as species from the Great Barrier Reef, could revolutionise shipping. Andrew’s research is sponsored by the Defence Science and Technology Organisation, and he is also collaborating with a number of companies to fabricate textured coatings that repel fouling. For more information contact Andrew Scardino, andrew.scardino@jcu.edu.au
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