INSUBCONTINENT EXCLUSIVE:
Image copyrightAilbhe KavanaghImage caption
Whales are having to use more energy to communicate
There is
a rising din in the oceans - and whales are having to struggle to compete with it
nightclub," explains says Mark Jessopp at University College Cork.Dr Jessopp was recently involved in a research project to study the
effects of marine seismic surveys on animals such as whales and dolphins.He and his colleagues found a "huge decrease" in sightings of such
species when the work was going on, even when accounting for other factors such as weather
Image copyrightTom HartImage caption
Mark Jessopp studies the effects of seismic surveys on sealife
Seismic surveys are carried out by a range of organisations, including oil and gas companies, as a means of mapping what lies beneath the
Shockwaves fired from an air gun - like a very powerful speaker - are blasted down towards the seabed
The waves bounce off features below and are detected again at the surface
The signal that returns reveals whether there is, for instance, oil locked in the rock beneath
The process creates a tremendous racket
"It's like an explosion," says Lindy Weilgart at Dalhousie University in Nova Scotia
She says that there is now plenty of evidence to show that many marine animals are negatively affected by the clamour.Image copyrightIan
WilmsImage caption
Quieter tech is not being introduced quickly enough, says researcher Lindy Weilgart
The effects aren't just felt by mammals like whales and dolphins, she adds
Fish and invertebrates such as crabs have also been seen to change their behaviour when noise levels rise
They can be put off feeding or become less able to detect predators, for example
And yet a technology exists that could be far less harmful
It is called marine vibroseis and is a low-energy alternative to air guns
Instead of explosive blasts, vibroseis uses smaller vibrations to transmit waves down to the seabed
It actually emits a similar amount of energy overall but spreads it over a longer period, meaning the survey has a less "shocking" impact
More Technology of BusinessStephen Chelminski, who invented the seismic air gun in the late 1950s, has become a proponent of vibroseis
because of its perceived environmental benefits
Dr Weilgart says there are many efforts to commercialise this quieter tech but she is unimpressed with how they are progressing
"It's just creeping along at a glacial pace," she says.Image copyrightGeneral DynamicsImage caption
Shell, Total and
ExxonMobil have spent years developing new seismic tech
Three of the world's biggest oil companies - Shell, Total and
ExxonMobil - have spent years developing a marine vibroseis device
Andrew Feltham, a geophysicist at Total who works on the project, says that the system has been shown to function as intended but requires
some further testing before it can be used in field work
He says that one benefit of the prototype device is that it doesn't produce noise across a wide range of frequencies
"We only emit energy within the frequency band of interest for the job at hand," he explains
This reduces the number of sea creatures that would hear noise generated by the device, lowering the environmental impact further.Norwegian
firm Petroleum Geo-Services (PGS), which helps oil and gas companies find offshore reserves of fossil fuel, has also been working on a
It has a different, more compact design that uses a stack of plates to generate vibrations.Image copyrightAilbhe KavanaghImage caption
Research shows dolphins and other marine life avoid areas where seismic surveys are going on
This allows for
the production of a strong seismic signal but stops the device shaking itself apart
"Using stacked plates is an ingenious solution," argues Bard Stenberg, a spokesman for PGS.The prototype has endured a 1,000-hour test in a
water tank and depths of 60m (197ft) in a harbour
However, it is yet to be trialled out at sea
Nathan Merchant is a bioacoustician at the UK's Centre for Environment Fisheries and Aquaculture Science (Cefas)
He says that vibroseis would actually be a better technology for organisations seeking to survey the seabed because it can be more finely
And yet, commercial interest in it has not really materialised."This is one of the areas where we need a bit of a push from the policy and
regulation side to create a market for that kind of technology," he argues
Image copyrightCefas - Adrian FarcasImage caption
A map of sea noise around the UK - red the noisiest and blue the
quietest
Dr Merchant studies noise levels in the seas around the UK
He and his team recently produced a detailed map of where the cacophony is greatest
However, while it is difficult to confirm exactly how noise levels have changed in recent decades, he says they have probably increased
overall."The answer to that is almost certainly 'yes'," he says.He points out that there are other significant sources of noise pollution at
These include noise from shipping, where, for example, propellers slicing through the water create a wake and with it a mighty rumbling
sound that can travel for hundreds or even thousands of kilometres
Then there are offshore wind farms, which rely on pile-drivers that bash huge columns into the seabed to create the base platform for
Engineers on such projects also occasionally have to clear unexploded ordnance left behind, for instance from World War Two
Detonating a bomb underwater creates a lot of noise but the bang can be softened by using a device to create a curtain of bubbles around the
Image copyrightGetty ImagesImage caption
The construction of offshore wind farms creates a lot of noise for sealife
Wind farms in the UK licensed to use bubble curtains for this purpose include Hornsea One and Two off the north-east coast
Currently under construction, the full Hornsea complex will eventually form the largest offshore wind installation in the world
Marine biologists continue to hope for technologies that will make human activity in the oceans quieter
Dr Jessopp acknowledges that seismic air guns are cheap and have been proven to work
With marine vibroseis still not available at a commercial scale, firms may not see any reason to change how they do things."In the absence
of any real viable alternative we've just kept doing it
It's kind of business as usual," says Dr Jessopp.So the seas will remain noisy for sometime and whales will have to continue to shout to be
