Macro invertebrates were identified to the lowest practical level (species level, when possible) and enumerated. Colonial, encrusting epifaunal species were allocated a P value. A reference collection was prepared with one individual of each species identified retained.
72. EMU undertook quality control (QC) checks on a representative number of whole samples, as well as the entire reference collection in compliance with internal analytical QC criteria.
73.
Faunal biomass analysis was based on a wet blot method with estimates of ash free dry weight (AFDW) based on conversion factors provided by Eleftheriou and Basford (1989). Mollusc biomass included the weight of the flesh plus shell.
2.5 Data Rationale Before the Analysis 74.
Of the total 49 sites sampled, the 39 sites along the cable route were used in the analysis for this report. The sites omitted were located in the East Anglia THREE and East Anglia FOUR windfarms (see Figure 0.1). Raw results from the analysis of faunal and environmental samples for omitted data are presented in Appendix M and Appendix N respectively. Biotope assessment for these sites was also carried out and the results included in Appendix O.
2.6 Statistical Analysis 75.
The macro invertebrate community structure and sediment distributions were investigated by employing univariate diversity indices (Shannon Wiener diversity index; Pielou’s eveness and Simpson’s dominance index). For multivariate statistical analyses the Plymouth Marine Laboratories PRIMER v6 (Plymouth Routines in Multivariate Ecological Research) suite of programs was used (Clarke and Warwick, 2001; Clarke and Gorley, 2006).
76.
Sediment data were also imported into PRIMER and subjected to hierarchical clustering using Euclidean distance as the similarity measure. In addition, Principal Components Analysis (PCA) ordination was performed on the sediment data.
77.
Benthic Characterisation Report November 2013
The Shannon Wiener diversity index is a measure of biodiversity based on the number of species present and the number of individuals of each species. If a few species dominate, the index value is low. A greater number of species and a more even distribution of species both result in an increase in Shannon's diversity. Pielou’s eveness is a measure of how the numbers of individuals are distributed across the East Anglia THREE and FOUR Offshore
