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completion of a conservation-focused review of the side-scan sonar data acquired across the East Anglia ONE site.

 Assessment of the presence of absence of S.spinulosa in grab samples. This was done visually, using both photographs and survey field notes, and through enumeration of animals within grab samples. Where S. spinulosa was found, relevant measurements with respect to ‘reefiness’ (Hendrick and Foster (2006)) were recorded. A density of more than 375 individuals in any one grab may was considered to represent potential reef (Foster-Smith, R.L. and White, W.H., 2001).

 Review of video imagery of the seabed prior to of following grab samples where side-scan sonar imagery or grab samples revealed notable amounts of S. spinulosa.

 Modelling was also used to assess the importance of the S. spinulosa identified within the East Anglia ONE site. The model used kriging interpolation using side scan sonar “anomalies” and reefiness.


S. spinulosa was identified as present within 19 seabed images gathered from across the East Anglia ONE site and tidal excursion survey area. Analysis of the images did not however indicate that reef was present.

8 Data gathered during the benthic survey in the East Anglia ONE site found the abundance of S. spinulosa to be in excess of 375 animals at three locations.

9 Due to a lack of geophysical data at the time of the offshore cable corridor survey a drop-down video system was deployed prior to the benthic grab survey to ascertain the presence or absence of S. spinulosa reef at each sampling location (this followed instruction from the relevant regulatory advisers). The drop-down video identified the presence of S. spinulosa reef at a single station (Station 19) within the offshore cable corridor. Geophysical survey data (acquired post benthic grab survey) were then analysed which indicated that this location contained S. spinulosa as patchy agglomerations in between areas of sand ripples.

10 Analysis of samples from all grab sites within the offshore cable corridor showed that the maximum number of individuals per grab was 185, ie below the ‘reef’ threshold.

11 The locations of potential reef habitat within East Anglia ONE and the offshore cable corridor are shown in Volume 6, Figure 9.10 of the ES. The areas identified are small in extent and discrete. On the basis of the data collected for the EIA survey, East Anglia ONE is unlikely to be a ‘hotspot’ for Annex I reef. This is confirmed within the SoCG with NE/JNCC (Section 2.1, Statement 4a).

Outline Operations and Maintenance Monitoring Plan Offshore Page 6

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