Noise from Offshore Wind Farm Construction Could Harm Marine Mammal Life

Offshore wind farms are being championed as a major player in future carbon-reduction targets, but their construction could have consequences to marine life, according to an international team of researchers, who have developed a method for assessing how the construction of the wind farms, especially the noise involved, will impact marine mammal populations.

"Pile-driving during the construction of offshore wind farms produces an incredible amount of noise," said Helen Bailey, one of a group of scientists at the University of Maryland Center for Environmental Science who are studying the impacts of wind turbines on the environment. "This is potentially harmful to marine species and has been of greatest concern to marine mammal species, such as protected populations of seals, dolphins and whales."

Bailey and her colleagues recorded the noise from pile-driving underwater at a distance of 500 meters (about 9 football fields) and 35 kilometers (18 miles) to assess how the noise could impact marine mammals.

To the human ear, the pile-driving at the closer range sounds similar to an off-balance clothes dryer tumbling out of control. At a distance, the noise is fainter but still pronounced. Audio files of the pile-driving noise are available here.

The researchers paid particular attention to harbor seals, which can be impacted by the noise in several ways.

"Loud construction activities can cause traumatic hearing injury or death at close range," the University of Maryland Center for Environmental Science said in a news release about the new research. "The disturbances may lead seals to avoid the area and lose favorite feeding grounds, potentially causing greater competition in other areas. It could also have an impact on reproduction or survival rates. Changes in hearing sensitivity could make seals more vulnerable to predation, and make it more difficult to find food or to find mates."

The study's lead author, Paul Thompson of the University of Aberdeen, said the research framework "takes a worst case assessment of the short term impacts of noise and how these may influence longer term population change, thereby providing information that allows regulators to balance their efforts to meet both climate change targets and existing environmental legislation."

The research is published in the November issue of Environmental Impact Assessment Review.