Cetaceans are endangered by offshore windfarms, claims UK group

CHIPPENHAM, UK, August 22, 2007. The growth in offshore windfarms poses a potentially devastating threat to whales, dolphins and porpoises, according to a report from an environmental protection group.

The driving of turbine piles and other noises during construction of facilities can be heard by marine creatures in shallow water up to 80 km away, while the noises can damage their hearing at close range and cause dramatic changes to behaviour at distances of 20 km, claims the Whale & Dolphin Conservation Society in a 122-page report, ‘The Conservation of British Cetaceans: A review of the threats & protection afforded to whales, dolphins & porpoises in UK waters.’ To accompany the report, WDCS produced a ‘score sheet’ which graded the UK government at 1 out of a score of 10 for its action to avoid the most serious threats to the UK’s wildlife.

The laying of cables and disturbances caused by service boats means the acoustic impact continues long after the building of an offshore windfarm is finished, it adds. Only five offshore windfarms are operating in Britain, but seven are under construction and 14 are planned.

“With regard to offshore windfarms, underwater turbines, wave energy generators and other forms of ‘renewable energy’ generation, consideration needs to be given to the potential impacts of construction, operation and decommissioning,” the report explains. “The pile driving, for example, that is used to build windfarms is a substantive source of noise. Enthusiasm for green energy should not be allowed to override genuine marine conservation concerns.”

Cetaceans are being “adversely affected by various human generated activities,” it warns. “The precise significance of virtually all of these is poorly known and this situation is made even worse because we also know little of the distributions and habitat needs of these animals. In short, we may well be in danger in the seas of repeating the mistakes made earlier on land for many terrestrial species: driving them from their natural habitats, reducing ranges and depleting or even extinguishing populations.”

“In order to provide a source of renewable energy for the UK, there has been considerable investment in the development of alternative technologies and, in particular, windfarms,” says senior author Chris Parsons. “Due to competition over land use, land-based windfarms are becoming harder to site, therefore attention has become focussed on marine windfarms.”

“Although, on the one hand, being a renewable source of energy, windfarms have a positive environmental impact, on the other they could possibly have a negative impact on cetaceans due to the noise they produce and possible impacts on habitats and the marine ecosystem in general.”

“Their potential to displace animals is one concern and one that it is particularly difficult to gauge, since so little is known about current cetacean distributions around the UK,” it continues. “When in operation, windfarms produce a considerable amount of low frequency noise, which research has calculated increases background levels of marine noise by 80-110 dB. However, the construction of windfarms also produces considerable amounts of marine noise (260 dB), likewise the laying of submarine cables to service the windfarm site (176 dB).”

A study funded by a UK statutory authority investigated the possible effects on cetaceans and marine fish from noise and vibrations of offshore windfarms and determined that there would be significant effects during construction, with disturbance reactions likely to a distance of several kilometres. Within 100 m of a windfarm construction, it was estimated that noise levels might be so severe that cetaceans may suffer acoustic trauma.

Disturbance reactions by cetaceans to noises produced by windfarms have been documented, the report claims, and researchers playing recordings of noises produced by a 2 MW turbine (frequency 800 Hz) “reported that the distance between harbour porpoise surfacings and the sound source significantly increased, and there was a significant increase in porpoise echolocation rates, thus indicating disturbance of the harbour porpoises by windfarm noise.” The disturbance occurred even though the animals should not have been able to detect these low frequency sounds, according to hearing sensitivity tests conducted on captive porpoises.

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