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27 March 2010 | NewScientist | 57 Smart buoys alert oil rigs to soliton wave threat A RARE example of an undersea dawn chorus has been recorded off the coast of southern England during an experiment to measure ambient noise in the oceans. It found that marine organisms in the area increase their chatter at sunrise and sunset, though only in the summer. Marine choruses were discovered by American scientists developing sonar systems during the second world war. Since then many examples have been found in tropical waters, where evening choruses are common. Dawn choruses, on the other hand, are much less common, particularly in temperate waters, says Doug Cato, a bioacoustician at the Defence Science and Technology Organisation in Australia. Cato has been recording marine choruses for 40 years. Edward Harland, a consultant at Chickerell Bioacoustics in Dorset, made the latest discovery while investigating undersea noise as a tool to assess the impact of marine engineering projects on the ocean environment. Exactly what is making the cacophony of clicking he recorded isn’t clear. Harland has ruled out shrimp, which are known to create choruses elsewhere. “There are too few in these waters,” he says. Other potential culprits include corkwing wrasse and goby. Identifying the perfomer won’t be easy, says Cato, and trying to make reference recordings won’t help. “Placing fish in a tank to record their sounds often doesn’t work because they may not vocalise,” he says. Mystery sea creatures make an unusual din “Advance warnings issued to rig owners gave staff 10 hours to cease drilling and prepare” –Now we can spot them coming– –Goby gabbler– HANS LEIJNSE/FN/MINDEN/FLPA MODIS
