389. At the Naikun Offshore Wind Farm in British Columbia, JASCO (2009) predicted that sound pressure levels from the centre of the 396MW windfarm (110 x 3.6MW turbines) were greater than 120dB re 1 μPa rms SPL at ranges less than 8.5km.
390. The maximum number of operational turbines within the East Anglia THREE site is 172 devices (based on the 7MW design, Table 12.2). The minimum spacing between operational turbines will be 675mx 900m.
12.6.2.1.1 Sensitivity
391. The low-level noise generated during operation is likely to be detected by marine mammals only at short distances over background noise levels and below levels which would elicit a response (Madsen et al. 2006; Thomsen et al. 2006). The overall effect of the operational noise and the ability of marine mammals to perceive this noise will be largely dependent on ambient noise levels and wind speed. However, the operational wind turbines within the project are not expected to result in increased noise levels more than a few kilometres from the windfarm boundary.
392. Empirical data exist to support no lasting disturbance or exclusion of small cetaceans or seals around windfarm sites during operation (Tougaard et al. 2005; Scheidat et al. 2011). Data collected suggests that behavioural responses for harbour porpoise and seal may only occur up to a few hundred metres away (Touggard and Henriksen 2009; McConnell et al. 2012).
393. Touggard and Henriksen (2009) further show that even masking from operational noise is unlikely to impact harbour porpoise and seal acoustic communication, due to the low frequencies and low levels produced. Scheidat et al. (2011) reported an attraction of harbour porpoise to an operational Dutch windfarm site, where abundance was higher within the windfarm compared to a similar environment in near-by areas. This was assumed to be due to decreased fishing and vessel activity and increased food availability (Scheidat et al. 2011).
394. Lidell (2003) concluded that noise levels of the operating windfarm would be too low to cause injury to marine mammals. No behavioural response estimates are available from modelling of the Naikun offshore windfarm operational noise.
395. Comprehensive environmental monitoring has been carried out at the Horns Rev and Nysted windfarms in Denmark during the operational phase between 1999 and 2006 (Diederichs et al. 2008). Numbers of porpoise within Horns Rev were thought to be slightly reduced compared to the wider area during the first two years of operation it was, however, not possible to conclude that the windfarm was solely responsible for this change in abundance without analysing other dynamic
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 12 Marine Mammal Ecology Page 92
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