Noise Pollution Causes European Eels to be Gulped Down by Hungry Predators

Noise pollution is a growing problem as shipping traffic increases. Now, scientists have found that eels may be facing some unprecedented risks due to this cacophony. It turns out that these fish are losing crucial responses to predator threats, which means that populations could face drastic cuts as hungry predators line up for an easy meal.

In this case, the researchers found that European eels were 50 percent less likely to respond to an ambush from a predator due to ship noise. Those that did respond had 25 percent slower reaction times. In fact, those that were pursued by a predator were caught more than twice as quickly when exposed to ship noise.

"Our findings demonstrate that acute acoustic events, such as the noise of a passing ship, may have serious impacts on animals with direct consequences for life-or-death behavioral responses," said Steve Simpson, one of the researchers, in a news release. "If these impacts affect whole populations then the endangered eel, which has seen a 90 percent crash in abundance over the past 20 years due to climate change, may have one more problem to deal with as they cross busy coastal areas."

That's not all that the scientists found, either. Wanting to know why the eels had such delayed response times, the researchers tested physiology and spatial behavior. They found heightened stress levels and reduced lateralized behavior (right-left preferences) during noisy times.

"The fact that eels were affected physiologically and spatially suggests that other important functions may also be affected," said Andy Radford, co-author of the new study. "We focused on anti-predator responses as, unlike impacts on movement or feeding, there is no way to compensate for being eaten after the disturbance goes away."

The findings reveal the importance of assessing not only chemical pollution, but also noise pollution. It turns out that noisy environments can be just as deadly to marine animals, and shows how crucial it is to manage shipping traffic in order to mitigate the impacts of this noise.

The findings are published in the journal Global Change Biology.