Exposure to Ship Noise Increases Metabolic Rates of Crabs: Study

A new study finds that ship noise increases the metabolic rates of crabs, indicating higher levels of stress. The findings of the study are published in the journal Biology Letters.

A team of researchers from University of Bristol and University of Exeter, U.K., exposed shore crabs of different sizes to recordings of ship noise in order to study the impact of noise on the marine animals.

They found that noise increases the metabolic rates of the crabs, indicating elevated stress. The research team also noticed that the larger individual crabs were affected more than the smaller ones.

"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. This is the first indication that there might be different responses to noise depending on the size of an individual," Dr. Andy Radford, from the University of Bristol, said in a statement.

Exposure to ship noise could have significant implications on the growth of the crabs. If the metabolic cost of noise causes the crabs to spend more time foraging to compensate, it might face the risk of predation, said the researchers. They found little evidence of the crabs getting accustomed to noise over time.

These findings could also have implications for fisheries in busy shipping areas, where larger crabs are more affected. Similarly, operational noise in farms could affect the growth of many crustacean species like prawns that are grown in aquaculture. On the contrary, if reducing noise reduces metabolic costs, then quieter aquaculture facilities might yield more profits, the researchers concluded.

Previous studies have shown the effects of underwater noise and vibrations produced by ship traffic, touristic boats, seismic surveys, oceanographical experiments, and underwater explosions on marine animals. In addition to causing increased stress levels, the acoustic trauma might affect the hearing ability of marine mammals.

Increased levels of sound might also trigger behavioral changes in the animals and cause damage to their organs.