Marine fouling, where barnacles, mussels, sponges and algae attach to a ship's hull, is a huge cost to the shipping industry through increased drag. Millions of dollars are spent each year controlling fouling on commercial vessels and a lot of it involves applying toxic anti-fouling paint.
In world-first research, NIWA and Auckland University scientists have discovered that fouling of vessels is greatly increased by the underwater sounds produced by the vessels. Ships' generators continue to run while they are in port and appear to produce a lot of underwater noise.
Trials with underwater speakers and recording of cruise ships, logging and container ships, and mussel larvae showed the larvae settled on the noisy hulls about 40 percent quicker than the silent hulls, said NIWA biosecurity scientist Selena Wilkins.
"The mussel larvae settled very quickly - within a few hours. This is within the time frame that the larvae would be exposed to the noise from a generator in a vessel in port.
" The "very exciting" research could have huge implications for not only the efficiency of ships, but also for biosecurity as many invasive organisms can be spread by ships' hulls, Dr Wilkins told NZ Newswire.
The scientists are hoping to suggest ways of reducing the underwater noise produced by ships, such as dampening or eliminating sound or switching to shore-based electrical supply when berthed.
It is known that sound triggers larvae of many coastal organisms to settle more rapidly.
Fish and crab larvae are attracted toward the underwater sound of waves breaking on coastal reefs and noises produced by other reef-dwelling organisms during feeding.
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