Given the scale of survey conducted to date and the largely homogeneous nature of the benthos, it is intended that data gathered for the Zone and for East Anglia ONE will be used to characterise the benthos for the purposes of the EIA for East Anglia THREE and East Anglia FOUR.
15.
It has been agreed by Cefas and the MMO (see Appendix 1) that given the level of debate there is in the scientific and regulator community regarding the usefulness of biotope mapping, particularly at the regional scale; this may not be the most appropriate method of presenting the benthic data.
16. APEM Ltd (2012) undertook an exercise to review data gathered at East Anglia THREE and FOUR to determine if this was sufficient to characterise the benthos or whether further survey was required (see Appendix 2). This study concluded that for the windfarm site the existing data were sufficient and that for the areas of cable route not covered by previous survey a further 36 benthic grab stations needed to be sampled (The power analysis report is appended to this note). This approach was discussed with and approved by Cefas/JNCC (see Appendix 3). To be certain of comprehensive coverage of East Anglia THREE and East Anglia FOUR windfarm sites the 2013 survey (See Table 2 above) included five grab samples in each of the windfarm sites and 48 stations within the cable route (Figure 1 below).
17.
In addition a further 11 video trawls were completed across the two windfarm sites and 41 within the cable route. Furthermore three beam trawls (2m) were completed within each wind arm site and six within the cable route (Table 2).
Table 2 Summary of Benthic surveys within East Anglia THREE and FOUR and the Cable route Data Souce Grabs
East Anglia THREE
49 from the zonal campaign; 5 from recent surveys (Spring 2013)
Video trawls Benthic Trawls
Contaminated sediment samples
5 from recent surveys (Spring 2013)
4 from the zonal campaign and 3 from recent surveys
10% of all grabs East Anglia FOUR
49 campaign; 5 from recent surveys (Spring 2013)
6 from recent surveys (Spring 2013)
6 from the zonal campaign and 3 from recent surveys
10% of all grabs
10% of all grabs analysed for contaminants
Evidence Plan Benthic Ecology Method Statement
East Anglia THREE & East Anglia FOUR Offshore Windfarms
September 2013 Page 15
Combined Cable Route
39 from the zonal campaign; 39 taken from EA ONE and 48 from recent surveys (Spring 2013)
