Marine mammals under threat from ocean noise pollution


Whales and dolphins usually suffer most from noise pollution

Oceans becoming noisier as sounds travel further in increasingly acidic water

Ocean noise pollution is getting worse and harming marine mammals because of the affects of carbon emissions and ocean acidification, according to a new study.

Rising carbon emissions are making the oceans more acidic as the CO2 combines with the seawater to produce carbonic acid.

In turn, ocean acidification and rises in seawater temperature make seas less able to absorb low-frequency sounds, so noise travels further. This is linked to deafness in dolphins, beachings and loss of habitat as marine mammals seek quieter surroundings.

The findings, published by scientists from the University of Hawaii and the University of California, provide more evidence of the damage caused by ocean acidification.

‘This is a highly significant paper because attention has focused on the effects of ocean acidification on calcification [such as the dissolving of shellfish shells], but not on how it will completely change the acoustics of the oceans,’ said Dr Jason Hall-Spencer, a Lecturer in Marine Science and Engineering at the University of Plymouth.

Noisier oceans

According to data modelling by the lead author of the study, Dr Tatiana Ilyina from the University of Hawaii, sound absorption for low-frequency noise could fall by up to 60 per cent by 2100 in high-latitude, deep oceans if we do not significantly cut back carbon emissions.

Whales and dolphins were likely to be affected worst, principally by being frightened away.

This is a particular problem for specific species of dolphin or whale that are endemic to certain habitats. Dr Hall-Spencer said that the construction of an airport in Hong Kong had had a negative impact on the pink dolphins there that were specific to that region.

However, in some cases the damage to mammals could be worse.
‘The most extreme effects reported are tissue damage or mass stranding of whales associated with military tests of active acoustic systems,’ said Dr Ilyina.

Marine species have been known to adapt to low-level manmade noise such as from shipping, which are dominated by natural sources of sound such as breaking waves and rain. But Dr Ilyina said more research was needed on the impacts of noisier seas on marine mammals.

Useful links

Full study

Ocean acidification: the facts
The marine campaign group Oceana has put together a fact sheet about ocean acidification
Ocean acidification to devastate commercial fisheries
Previous studies have focused on the impact of acidification on coral reefs but not other marine organisms
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