Noise could sound the death knell of ocean fish

In this file photo, reef fish swim among the coral in Kimbe Bay off the coast of Papua New Guinea's New Britain island.  

Growing levels of noise pollution in the ocean could drive fish away from their habitat into their deaths.

After developing for weeks at sea, baby tropical fish rely on natural noises to find the coral reefs where they can survive and thrive.

However, researchers from the University of Bristol School of Biological Sciences, working in the Great Barrier Reef, Australia, found that short exposure to artificial noise attracts fish to inappropriate sounds.

In earlier research, Steve Simpson from the School of Biological Sciences discovered that baby reef fish use sounds made by fish, shrimps and sea urchins as a cue to find coral reefs, according to a University of Bristol statement.

With human noise pollution from ships, wind farms and oil prospecting on the increase, he is now concerned that this crucial behaviour is coming under threat.

He said, “When only a few weeks old, baby reef fish face a monumental challenge in locating and choosing suitable habitat. Reef noise gives them vital information, but if they can learn, remember and become attracted towards the wrong sounds, we might be leading them in all the wrong directions.”

Using underwater nocturnal light traps, Simpson and his team collected baby damselfish as they were returning to coral reefs.

The fish were then put into tanks with underwater speakers playing natural reef noise or a synthesised mix of pure tones.

The next night the fish were put into specially designed choice chambers (long tubes with contrasting conditions at each end in which fish can move freely towards the end they prefer) with natural or artificial sounds playing.

All the fish liked the reef noise, but only the fish that had experienced the tone mix swam towards it, the others were repelled by it.

Simpson said, “This result shows that fish can learn a new sound and remember it hours later, debunking the three-second memory myth.”

His collaborator, Mark Meekan, added, “It also shows that they can discriminate between sounds and, based on their experience, become attracted to sounds which might really mess up their behaviour on the most important night of their life.”

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Printable version | Nov 29, 2020 7:56:46 AM | https://www.thehindu.com/sci-tech/energy-and-environment/Noise-could-sound-the-death-knell-of-ocean-fish/article16135289.ece

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