Underwater noise pollution is causing turtles to experience hearing loss, scientists say

Turtles may be more sensitive to sound than previously understood, researchers say

A red-eared slider (Andria Salas/ Woods Hole Oceanographic Institution)

Underwater noise pollution from activities such as shipping and offshore construction could cause turtles to experience hearing loss that may last from minutes to days, scientists have warned.

The study, which will be presented at the 2022 Ocean Sciences Meeting on Friday, could have implications for the survival of some threatened turtle species.

While previous studies have found the effects of noise in marine animals such as squids, fishes and whales, scientists, including those from Woods Hole Oceanographic Institution in the US, said that less work has been done on reptiles like turtles.

But the new research has indicated that these reptiles are more sensitive to sound than previously understood.

In the study, which has yet to be peer reviewed, researchers inserted a minimally invasive electrode just under the skin above a turtle’s ear to detect very small electrical voltages created by the turtles’ auditory system when they hear sounds.

They then determined the lower threshold of turtles’ underwater hearing and which tones or frequencies the reptiles heard best.

The experiments were focused on two non-threatened species of freshwater turtles, Trachemys scripta elegans and Chrysemys picta, scientists said.

They then exposed the turtles to loud, high amplitude white noise.

Researchers kept measuring turtle hearing for about an hour after exposing them to the noise and then removing it to see how the reptiles recovered their underwater hearing in the short term.

They then checked on the turtles two days later to see if recovery was complete.

While the turtles always recovered their hearing, they found that hearing loss usually lasted for about 20 minutes to over an hour.

But sometimes, the hearing had not recovered by the end of the testing hour, indicating the turtles needed more time to fully recover.

One turtle’s hearing, scientists said, was affected for multiple days.

“If this occurs in nature, turtles would be less able to detect sounds in their environment on these timescales, including sounds used for communication or warning them of approaching predators,” Andria Salas, a researcher at Woods Hole Oceanographic Institution, said in a statement.

“Over half of turtle and tortoise species are threatened, and noise pollution is an additional stressor to consider as we work towards protecting these animals.” Dr Salas added.

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