10.5.2.4 Targeted samples 99. During the East Anglia Zone surveys 77 grab samples were acquired to target features of interest as identified using the geophysical survey data (see Appendix 10.2 for further detail). Four of these samples (Figure 10.7) are located within the offshore cable corridor. When incorporated into the multivariate community characterisation these samples fitted into groups Q, N and G.
10.5.3 Epifaunal Communities 100. The following section describes the epibenthic communities within the three study areas. As detailed in section 10.4.2.2 several surveys were undertaken within the East Anglia Zone, East Anglia THREE site and offshore cable corridor. In order to characterise epifaunal communities, two of these data sets, the East Anglia Zone and the East Anglia THREE / FOUR epibenthic surveys were combined to create a larger data set.
101. The epibenthic are semi quantative therefore in terms of comparing samples across the survey area it has less meaning than using the infanul grab data as described in section 10.5.2. However, a semi-quantative comparison still gives an indication of the relative abundance of the different species.
102. Many fish species (including sandeels) were recorded within the epifaunal data; these have been removed from this analysis, as fish are not considered part of the benthic community for the purposes of this assessment. These are considered in Chapter 11 Fish and Shellfish Ecology.
10.5.3.1 Epifaunal communities in the East Anglia Zone 103. Epifaunal abundance varies across the East Anglia Zone with relatively high abundances occurring in the north-west and low abundances in the East Anglia THREE site (Figure 10.8). Species diversity (identified as the number of different species found within a sample) was more evenly distributed over the East Anglia Zone with slightly higher diversity recorded in the western half (Figure 10.9).
104. By far the most dominant class of organism within the epifauna were the Malacostraca (Diagram 10.7) which include crabs, lobsters, shrimp, krill, and amphipods. Within this group the brown shrimps Crangon allmanni (35,354 individuals identified across 83 sample stations) and Crangon Crangon (1,773 individuals identified across 43 sample stations) were numerous. These two species play an important ecosystem function role within the southern North Sea and are a key food source for flatfish. Also abundant were the hermit crabs Paguridae (1,897 individuals identified across 88 sample stations) and the crab Liocarcinus holsatus (1,946 individuals identified across 81 Sample stations).
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 45
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