biotopes identified are considered to be rare within the southern North Sea the value of this particular receptor is considered to be low (Table 10.6).
168. Subtidal sands and gravel are present throughout the entire East Anglia Zone (Figure 10.2) as well as the remainder of the southern North Sea. Dredging, jetting and trenching would all lead to temporary disturbance of this habitat but it is expected to recover quickly as a result of the bed shear within the region. The area of this habitat that may be affected by cable installation constitutes a small proportion of the available habitat in the southern North Sea resulting the assignment of a low magnitude.
169. The East Anglia ONE benthic survey identified the potential for S. spinulosa reef at one location in the offshore cable corridor (Figure 10.11) with a reef value score of 3 out of 5. Further information on how this score has been derived is provided in section E.2.1 of Appendix 9.1 of the East Anglia ONE Environmental Statement (East Anglia One Limited 2012). Any direct impacts on S. spinulosa reef would be avoided through the embedded mitigation measure of micro-siting export cables to avoid known areas of potential Annex I reef habitat.
170. Mussels belonging to the family Mytilidae were present throughout the nearshore section of the offshore cable corridor (Figure 10.12) although it should be noted that no reef structures formed by mussels were identified. Mussels are of interest due to their potential as a food source (both commercially and ecologically) and their potential to form biogenic reef which is an Annex I habitat. Mussels are intolerant of substratum loss because they require hard substrata to attach to but are likely to recover quickly through rapid larval recruitment. If a mussel is displaced but not damaged, it has the ability to reattach to new substrata so it is considered tolerant of displacement (Tyler-Walters 2008). Mytilidae are therefore considered to have a low sensitivity to the effect of physical disturbance during export cable installation. Again if any potential reef is located in pre-construction surveys these would be avoided by micro-siting export cables.
171. The important flat fish food source brown shrimp and the commercially exploitable edible crab were identified as present within the offshore cable corridor. These species are highly mobile and would be expected to evade the disturbance caused by dredging, jetting and trenching activity. Furthermore, these species are both assessed by MarLIN as having low sensitivity and high recoverability to physical disturbance (Neal 2008, Neal and Wilson 2008). Taking this into account, along with the fact that neither are considered to be rare, the sensitivity of these receptors is considered to be low.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 61
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