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Motorboat Noise Helps Marine Predators

An international research team has found that noise from passing motorboats reduces the ability of coral reef fish to flee from predators. As a consequence they are captured more easily and their survival chances are halved.

Prof Mark McCormick of the ARC Centre of Excellence for Coral Reef Studies at James Cook University said that the study, published in Nature Communications (www.tinyurl.com/gsjsges), “shows that juvenile fish become distracted and stressed when exposed to motorboat noise, and predators capitalise on their indecision”.

“We found that when real boats were motoring near to young damselfish in open water, they became stressed and were six times less likely to startle to simulated predator attacks compared to fish tested without boats nearby,” said Dr Stephen Simpson of the University of Exeter, who led the study.

The team of scientists combined laboratory and field experiments, using playbacks and real boat noise, to test the impact of motorboat noise on the survival of young ambon damselfish during encounters with their natural predator the dusky dottyback.

The team is optimistic about the possibilities for management of noise and its potential impact. “Unlike many pollutants, we can more easily control noise,” McCormick said. “We can choose when and where we make it, and with new technologies we can make less noise. For example, we could create marine-quiet zones or buffer zones, and avoid known sensitive areas or times of year when juveniles are abundant.”

Managing local environmental stressors such as noise is an essential first step in protecting the marine environment. “You might argue that climate change is a bigger threat to reef life, but if we can reduce the effect of local noise pollution we build greater resilience in reef communities to looming threats such as global warming and ocean acidification,” said Dr Mark Meekan of the Australian Institute of Marine Science.