The most extensive studies of underwater sound radiation from operational offshore wind turbines have been in connection with potential impacts on marine mammals, and the majority of these studies have been performed in Europe. For example, recordings of underwater noise from three different types of wind turbines in Denmark and Sweden (Middelgrunden, Vindeby, and Bockstigen-Valar) during normal operation as reported in 2009 [EU5] revealed that the radiated noise exceeded background levels only at frequencies below 500 Hz. While porpoises and seals might exhibit behavioral reactions to the noise at close range, "the noise is considered incapable of masking acoustic communication" by these mammals [EU5]. Although the impact of noise radiated by pile driving during construction of offshore wind farms on marine mammals may be significant [EU1, EU3], earlier studies [EU2, EU4] reinforce the conclusion [EU5] that the low-level, low-frequency underwater sound radiated by operational wind farms is anticipated to have minimal impact on marine mammals.
A 2003 report by the National Research Council [US1] titled "Ocean Noise and Marine Mammals" and a 2009 report to Congress prepared by DOE on potential environmental impact of offshore energy technologies [US2] should also be consulted for reviews of studies concerned with marine mammals.
US.1
"Ocean Noise and Marine Mammals"
Committee on Potential Impacts of Ambient Noise in the Ocean on Marine Mammals
Ocean Studies Board
Division on Earth and Life Studies
National Research Council of the National Academy of Sciences
Washington, D.C.
2003
US.2
"Report to Congress on the Potential Environmental Effects of Marine and Hydrokinetic Energy Technologies"
Department of Energy, Wind and Hydropower Technologies Program
Dec. 2009
EU.1
"Assessment of sub-sea acoustic noise and vibration from offshore wind turbines and its impact on marine wildlife; initial measurements of underwater noise during construction of offshore windfarms, and comparison with background noise"
J. R. Nedwell, J. Langworthy, D. Howell
COWRIE (Collaborative Offshore Wind Research Into the Environment, UK)
Report No. 544 R 0424
2003
EU.2
"Wind turbine underwater noise and marine mammals: implications of current knowledge and data needs"
P. T. Madsen, M. Wahlberg, J. Tougaard, K. Lucke, P. Tyack
Mar. Ecol. Prog. Ser., Vol. 309: 279-295
2006
EU.3
"Effects of offshore wind farm noise on marine mammals and fish"
F. Thomsen, K. Lüdemann, R. Kafemann, and W. Piper
biola (biologisch-landschaftsökologische arbeitsgemeinschaft) and
IfAF - Institut für angewandte Fischbiologie GmbH
on behalf of COWRIE Ltd, Newbury, UK
July 6, 2006
EU.4
"Offshore Wind Farms and Marine Mammals: Impacts & Methodologies for Assessing Impacts"
Proceedings of the ASCOBANS/ECS Workshop (10 papers in this compilation)
Editor: Peter G. H. Evans
ECS Special Publication Series No. 49
February 2008
EU.5
"Underwater noise from three types of offshore wind turbines: Estimation of impact zones for harbor porpoises and harbor seals"
J. Tougaard, O. D. Henriksen, and L. A. Miller
J. Acoust. Soc. Am. 125, 3766-3773
June 2009