Plenty of fish suffer from water pollution, which takes a toll on their health and reproductive abilities. Yet there is another often-overlooked form of manmade pollution that also affects them: noise pollution.

The roar of boat engines and other manmade sources of loud noise can grate on our ears, but they also impact fish living underwater. When exposed to increased amounts of noise for longer periods, fish can experience stress, loss of hearing and various changes to their behaviors, explains a team of researchers at Cardiff University in the United Kingdom who examined the effects of noise pollution on fish.

Worse: fish can also have their immune system compromised, and yet “the functional effects of this impacted immunity on disease resistance due to noise exposure have remained neglected,” the scientists write in a study published by The Royal Society.

To examine the effects of noise on fish, the scientists directed random blasts of white noise into fish tanks containing guppy fish to see whether and how noise pollution affected their susceptibility to parasitic infection. They blasted one group of fish with “acute” noise for a whole day and another group for seven days.

They also infected all the fish with a parasite, either after exposing them to noise or during such exposure, while leaving a third control group of similarly infected fish in a tank kept silent.

“[Fish] experiencing acute noise suffered significantly increased parasite burden compared with those in no noise treatments. By contrast, fish experiencing chronic noise had the lowest parasite burden,” the researchers explain in their study.

“However, these hosts died significantly earlier compared with those exposed to acute and no noise treatments,” they add. “By revealing the detrimental impacts of acute and chronic noise on host-parasite interactions, we add to the growing body of evidence demonstrating a link between noise pollution and reduced animal health.”

Fish aren’t the only aquatic animals affected by noise pollution, of course. Researchers at the University of Belfast found last year that a variety of other creates are affected, including amphibians, arthropods, mollusks and reptiles. Nor is it only noise that affects aquatic animals. So does light pollution in coastal areas, a team of British scientists behind another recent study has found.

“[U]nless we take action now it is clear that biologically important light pollution on the seafloor is likely to be globally widespread, increasing in intensity and extent, and putting marine habitats at risk,” warned Thomas Davies, a lecturer in Marine Conservation at the University of Plymouth who was the paper’s lead author.

Together, noise and light pollution from manmade sources pose even graver threats to aquatic animals and marine creatures worldwide.

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