Shrimps sound ocean acidity alarm
The snapping shrimp is the noisiest marine creature in coastal ecosystems.
Image: Tullio Ross/University of Adelaide
LONDON, 6 April, 2016 – The slow change in water chemistry as more and more atmospheric carbon dioxide dissolves in the sea and causes acidification could make the oceans much less noisy and slow the growth of life at the sea’s margins.
In one study, Australian scientists warn that as the acidity levels grow, the snapping shrimp may grow ever quieter. And in another study, Californian scientists have tested the water chemistry in coastal rock pools and discovered that they become most corrosive at night.
The snapping shrimp is the loudest invertebrate in the ocean. It forms bubbles in its snapping claw and uses this noise-making tool to warn off predators. And it can generate up to 210 decibels of noise, with important consequences for other creatures in coastal ecosystems.
Cracking sounds
“Coastal reefs are far from being quiet environments – they are filled with loud cracking sounds,” says Tullio Rossi, a marine acidification specialist at the University of Adelaide’s School of Biological sciences. “Shrimp choruses can be heard kilometres offshore and are important because they aid the navigation of baby fish to their homes. But ocean acidification is jeopardising this process.”
He and colleagues report in the Proceedings of the Royal Society B that they tested the shrimps under laboratory conditions of acidity predicted for the end of the century, and they found that both the frequency and volume of the snapping noises diminished.
The researchers also made field recordings at carbon dioxide-rich submarine volcanic vents, and observed the same pattern. They believe that the change of ocean pH levels affects behaviour, rather than impairing physiology.
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