Noisy Oceans Can be Life-Threateningly Distracting

Written by on July 31, 2013 in Fish, Other News, Whales & Dolphins

Earlier this month, researchers found that some blue whales change their behavior when exposed to military sonar. Military sonar has been blamed for many mass strandings, but it isn’t the only noise in the ocean that affects marine life and marine mammals aren’t the only creatures bothered by noise.

Common shore crab, Carcinus maenas.

Common shore crab, Carcinus maenas. Photo credit: BrentMWilson via photopin cc.

A study published a few weeks ago reveals that noise from passing ships has multiple negative impacts on the common shore crab (Carcinus maenas). Researchers from the Universities of Exeter and Bristol found that ship noise disrupts feeding for the crabs and that when threatened, they took longer to retreat to shelter, increasing the potential for predation.

“Crabs feeding on mussels were often distracted when ship noise was playing compared to quiet harbour recordings,” explained Matt Wale from the University of Bristol in a statement. “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.”

A previous study from the same research team found that ship noise also increases the metabolic rate and energy needs of common shore crabs. If the crabs require more energy and get distracted by noise when feeding, they will spend more time feeding to compensate. The more time they spend feeding, the higher their risk of becoming a meal for something else. This “elevated predation risk” could threaten the very survival of the species.

Another study from the Universities of Bristol, Exeter and Liège found that boat noise also disrupts orientation behavior in larval coral reef fish.

Fish are usually attracted to reefs by the sounds the reef inhabitants produce. In fact, they normally use sound from fish and other reef residents to find a suitable habitat, but when a reef is contaminated with boat noise, the fisher are more likely to swim away from the reef.

But it’s important to remember that the ocean would still be a very noisy place even without noise pollution from us humans.

To make that point, listen to the recordings from Oregon State University (OSU) of an iceberg breaking in two (although the cause of breaking, moving icebergs might be due to human-induced climate change, but that’s another story). You won’t believe how loud it is.

“We call the sounds ‘icequakes’ because the process and ensuing sounds are much like those produced by earthquakes,” explained Robert Dziak, a marine geologist at OSU’s Hatfield Marine Science Center in a news release.

The sounds produced by a breaking iceberg can be so loud that hydrophones near the equator actually record them. Check it out:

To learn more, read some of these related posts:

Copyright © 2013 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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