A study published in the journal Animal Behaviour found that the noise of passing ships disrupts feeding for the common shore crab. Perhaps worse, the team from the Universities of Exeter and Bristol also found that when threatened, crabs took longer to retreat to shelter and lost their natural 'play dead' behaviour.
In coastal seas around the world noise caused by humans is a dominant feature, with construction and transportation fundamentally modifying ocean soundscapes.
Working with the same common shore crabs that children delight in catching on crablines in UK harbours, the team found ecologically-critical effects of ship noise-playback on behaviour.
Matt Wale from the University of Bristol said: "Crabs feeding on mussels were often distracted when ship noise was playing compared to quiet harbour recordings. Furthermore, crabs took longer to retreat to shelter after simulated attacks in noisy treatments, and if turned upside-down they flipped back far quicker in noisy conditions rather than turning slowly to avoid attracting attention of potential predators."
Dr Steve Simpson from the University of Exeter said: "We have already found that ship noise raises the metabolic rate and energetic needs of crabs. If coupled with reduced foraging and worsened responses to predators, this cocktail of impacts may negatively affect growth, fitness, survival and, ultimately, harvested populations and whole ecosystems."
In the real world these findings present a double-edged sword. Less effective feeding in noisy environments means more time must be spent foraging to avoid starvation, during which crabs are exposed to their natural predators. But if crabs also perform less well when attacked, this elevated predation risk starts to threaten their very survival.
Dr Andy Radford from the University of Bristol said: "Ship noise is known to affect whale behaviour, and there is evidence that fish can also be affected by vessel noise. As a result behavioural studies of impact have focused on communication and movement patterns, while implications for marine invertebrates are relatively unknown."
A full copy of the paper is available online: http://www.sciencedirect.com/science/article/pii/S0003347213001991
About the University of Exeter
The Sunday Times University of the Year 2012-13, the University of Exeter is a Russell Group university and in the top one percent of institutions globally. It combines world-class research with very high levels of student satisfaction. Exeter has over 18,000 students and is ranked 7th in The Sunday Times University Guide, 10th in The Complete University Guide, 10th in the UK in The Times Good University Guide 2012 and 12th in the Guardian University Guide 2014. In the 2008 Research Assessment Exercise (RAE) 90% of the University's research was rated as being at internationally recognised levels and 16 of its 31 subjects are ranked in the top 10, with 27 subjects ranked in the top 20. The University has invested strategically to deliver more than £350 million worth of new facilities across its campuses in the last few years; including landmark new student services centres - the Forum in Exeter and The Exchange in Cornwall - and world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute. It has plans for another £330 million of investment between now and 2016. http://www.exeter.ac.uk
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