December 3, 2013
New Method for Monitoring Marine Noise And It’s Effect On Mammals
Previous research has found that underwater noise can be stressful or even harmful to sea creatures, and a team of UK scientists has devised a novel method for monitoring artificial noise in Scotland’s Moray Firth inlet, according to a newly published study in the journal Marine Pollution Bulletin.
Study author Nathan Merchant, a postdoctoral researcher at the University of Syracuse, said human activities related to Scotland’s growing wind power industry are increasing noise in the Moray Firth waters.
"Underwater noise levels have been increasing over recent decades, due to escalations in human activity," said Merchant, who co-authored the study while at the University of Bath in the UK. "These changes in the acoustic environment affect marine mammals because they rely on sound as their primary sensory mode. The disturbance caused by this man-made noise can disrupt crucial activities like hunting for food and communication, affecting the fitness of individual animals."
"Right now, the million-dollar question is: Does this disturbance lead to changes in population levels of marine mammals? That's what these long-term studies are ultimately trying to find out,” he added.
Many are predicting Scotland’s wind power sector will continue growing, resulting in more shipping passing through the study habitat. Some scientists have said these activities could negatively impact local marine mammals.
"Different ships emit noise at different levels and frequencies, so it's important to know which types of vessels are crossing the habitats and migration routes of marine mammals," Merchant explained. "The cumulative effect of many noisy ship passages can raise the physiological stress-level of marine mammals and affect foraging behavior."
Due to a current lack of data on the noise being made in Moray Firth, the study team developed a system using ship-tracking records and land-based, time-lapse photography. Based on these sources, the researchers are able to generate a ship-noise assessment toolkit. According to Merchant, the system could be applied to study noise from shipping in other locations.
"Nathan has been a great addition to our lab," said Susan Parks, a specialist in acoustic signaling who runs the Syracuse lab where Merchant currently works. "His strengths in signal processing and noise measurements for ship noise have expanded our capabilities.”
“Underwater noise is a global problem, as major shipping routes connect all of the economies of the world,” Parks added.
Marine mammals are not the only creatures affected by artificial undersea noise, as a study published earlier this year found that sounds of ship noise ramp up crab metabolism, potentially resulting in lowered yields for crabbers. Reported in the journal Biology Letters, the research suggested that commercial industry may indeed have a stake in reducing shipping noise.
"We found that the metabolic rate of crabs exposed to ship noise was higher than those experiencing ambient harbor noise, and that larger individuals were affected most strongly,” said study author Andy Radford, a behavioral ecologist at the University of Bristol. “This is the first indication that there might be different responses to noise depending on the size of an individual."