The potential ecological impact of the introduction of anthropogenic sound to the marine environment has received increasing attention in recent decades. Most interest has focused on acoustically sensitive or ecologically or commercially vulnerable species.
Potential impacts vary in severity from direct physical trauma and hearing damage through to behavioural disturbances, exclusions, fright responses and the masking of communication calls and prey / predator cues. SRSL were commissioned by OpenHydro to characterise the acoustic signature of their six meter diameter tidal turbine OCT0665 on a pile-mounted test structure at the EMEC tidal test site in Orkney.
The study used SRSL’s ‘Drifting Ears Method’ (Wilson and Carter, 2008) to record underwater sound levels, within the proposed array site. This customised method was applied because traditional boat/moored hydrophone methods expose the receiving element to contaminating ‘water-flow noise’, which is of prime consideration when monitoring ambient sound and device acoustic output in high-flow environments.
The data was analysed in-house and the results were then considered in the context of risk of auditory damage and audibility for four coastal marine mammal species present in the area.
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Press release, September 23, 2013; Image: openhydro