FEATURE SPONSOR
NOISE REDUCTION
Fish species including black sea bream, herring, plaice and cod have been tracked as part of research to model their response to underwater sound from piling activity
ASSESSING THE UNDERWATER SOUND
EFFECT OF IMPACT-PILING ON FISH What is the potential sound impact on marine life from the piling of turbine foundations?
And how can this be accurately assessed before construction commences to satisfy Environmental Impact Assessments, particularly where protected fish species may be affected? HR Wallingford carried out research on behalf of E.ON to gather data on the behaviour and response of black sea bream. The study aimed to advance the understanding of pile driving on wild black sea bream during the construction of windfarms off the south coast of the UK.
RAMPION WINDFARM
During the development of Rampion Windfarm, piling restrictions were imposed by regulators concerned about the potential effects of underwater sound on fish species during construction. This included a period from mid-April to the end of June when black bream nest. HR Wallingford carried out research into
the hearing abilities and responses of black sea bream to underwater sound, for which little information was previously available and modelled the response of the bream during nesting.
The research was carried out using flooded former shipbuilding docks and with piling simulated using a post driver, rather than by using the playback of recorded sound which previous similar studies had used. This meant that the particle motion component of underwater sound was maintained, so that the fish were exposed to more realistic conditions during the pile driving sound tests.
TRACKING The fish were tracked using a sophisticated system of high frequency pingers every two seconds, short enough to be able to detect a startle response or short term reaction
to underwater sound and allowing for the location and the depth of the fish be tracked accurately. As underwater noise propagation can be affected by the depth of water through which the noise is travelling, as well as the sediment type, the bathymetry and the seabed type of the study area were also taken into account in the modelling.
HR Wallingford Renewables Sector Lead, Samantha Dawson, explained: “The in-depth modelling we carried out showed that the piling activity required for the construction of Rampion Windfarm was unlikely to be detrimental to black bream. This enabled restrictions on piling work to be reduced and therefore, the offshore installation work was not delayed.”
HR Wallingford
www.windenergynetwork.co.uk
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