FFBC MPA
  1. Sample stations within the FFBC MPA were dominated by a range of taxa from the main taxonomic groups. Annelida provided the highest proportion of taxa at eleven sample stations, Mollusca at four sample stations, Crustacea at six sample stations and Echinodermata at seven sample stations. Sample stations within the FFBC MPA contained high abundances of juvenile Amphiuridae, as well as high abundances of juveniles A. filiformis, E. pusillus, S. spinulosa, D. grossularia and Astrorhiza. Sample stations within the FFBC MPA contained generally high numbers of individuals, with ST36 within the Scalp Bank and Wee Bankie section of the FFBC MPA containing 332 individuals however, ST07 in the section of the FFBC MPA overlapping with the east of the Proposed Development array area containing the lowest with 18 individuals.

Multivariate community analysis

  1. The results of the cluster analyses, SIMPROF tests and SIMPER analyses were used, together with the raw untransformed infaunal data, to assign preliminary infaunal biotopes to each sample station. In several instances, clusters that were identified as significantly different from each other in the SIMPROF tests were assigned the same biotope code. This was based on a review of the SIMPER results which indicated that the differences between the groups could be explained by differences in abundances of characterising species rather than the presence/absence of key species.
  2. The results of the hierarchical clusters analysis of the square root transformed infaunal dataset (including juveniles) together with the SIMPROF test identified 16 faunal groups that were statistically dissimilar, based on the SIMPROF test. Of these faunal groups, six contained only a single sample station ( Figure 3.10   Open ▸ ). The 3D MDS plot is presented in Figure 3.11   Open ▸ and the low stress value (0.15) indicates that this is a good representation of the data. The 2D MDS plot has not been presented as the 3D MDS plot presents a clearer representation of the data. Faunal group A (SIMPROF a; ST108) showed clear clustering away from all the other faunal groups with a Bray-Curtis similarity of 36.62%. The other single sample faunal groups include B (ST83), G(ST90), H(ST94), I(ST44), L(ST07). Faunal group P (SIMPROF p) showed the lowest Bray-Curtis similarity of 27.74%, while faunal group C (SIMPROF c) showed the highest Bray-Curtis similarity (52.78%) of all Faunal groups that contained more than one sample station. Faunal groups M, N, O and P (SIMPROF m, n, o, p) showed clustering with more similarity to each other than to the other groups. Within this cluster, Faunal groups N and O showed the lowest Bray-Curtis dissimilarity (71.18%). Faunal groups J and K (SIMPROF j and k) also showed a higher similarity with each other than with the other Faunal groups with Bray-Curtis dissimilarity of 71.79%. Faunal groups C and D (SIMPROF c and d) also showed a higher similarity with each other than with the other Faunal groups, with Bray-Curtis dissimilarity of 54.96%.

Figure 3.10:
Dendrogram of Infaunal Communities from Benthic Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.10: Dendrogram of Infaunal Communities from Benthic Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

  1. Multivariate community analysis was also undertaken on the infaunal data excluding the juveniles to understand the impact of these largely ephemeral taxa. The results of the hierarchical clusters analysis of the square root transformed infaunal dataset together with the SIMPROF test identified 22 Faunal groups, six more than for the data including the juveniles. These Faunal groups are discussed in comparison to the Faunal groups for the infaunal dataset which included juveniles in the following paragraphs.
  2. Faunal group C comprised three sample stations (ST50, ST70, ST71) located across the eastern and just outside the northern boundaries of the Proposed Development array area. Faunal group C was associated with sandy gravel and gravelly sand sediments. It was characterised by high abundances of Nematoda, the polychaetes Syllis parapari, Glycera lapidum and Hydroides norvegica, juvenile Mytilidae juveniles, Nemertea and the brittlestar Amphipholis squamata. All characterising species, with the exception of A. squamata were recorded in their highest abundance at a sample station within Faunal group C. It was distinct from the other Faunal groups due to the presence and abundance of the characterising species as well the absence of Astrorhiza and L. cingulata which separated it from Faunal group E as well as B. crenatus which separated it from Faunal group I. Faunal group C showed the highest Bray-Curtis dissimilarly with Faunal group F (95.97%) due to the presence of 12 species including the characterising species Leptochiton, the bivalve Clausinella fasciata and U. marina which were not present in Faunal group F. Faunal group C was allocated a preliminary biotope based on the infaunal data of SS.SMx.OMx.PoVen.
  3. Faunal group D comprised three sample stations (ST47, ST52, ST54) located across the western section of the Proposed Development array area, within the FFBC MPA. Faunal group D was associated with sandy gravel sediments. It was characterised by high abundances of Nematoda, Nemertea, A. squamata, Cheirocratus, the amphipod Nototropis vedlomensis, juvenile Ophiuridae and juvenile Mytilidae and the polychaete Psamathe fusca. Amphipholis squamata, Cheirocratus and N. vedlomensis were recorded in their highest abundance in a sample station within Faunal group D. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well as the absence of Astrorhiza which distinguished it from Faunal group P, as well as A. filiformis which distinguished it from Faunal group O. Faunal group D showed the lowest Bray-Curtis dissimilarity with Faunal group C (54.96%). Faunal group D was allocated a preliminary biotope based on the infaunal data of SS.SMx.OMx.PoVen.
  4. Faunal group E comprised two sample stations (ST36, ST65), one from outside the northern and one from outside the southern border of the western section of the Proposed Development array area. Faunal group E was associated with slightly gravelly sand and sandy gravel sediments. It was characterised by Astrorhiza, the polychaetes S. spinulosa, Pholoe inornata, H. norvegica, L. cingulata, Scalibregma inflatum, Cirratulus cirratus and Nemertea. The polychaetes P. inornata and S. inflatum were recorded in their highest abundance from sample stations within Faunal group E. It was distinct from the other Faunal groups due to the presence and abundance of the characterising species as well as the absence of D. grossularia which distinguished it from Faunal group B and U. marina which distinguished it from Faunal group H. Faunal group E was allocated a preliminary biotope based on the infaunal data of a non-reef forming version of SS.SBR.PoR.SspiMx.
  5. Faunal group F comprised 11 sample stations (ST80, ST81, ST82, ST85, ST86, ST87, ST88, ST98, ST99, ST106, ST109) located at the inshore section and just outside of the Proposed Development export cable corridor. Faunal group F was associated with muddy sand and slightly gravelly muddy sand sediments. It was characterised by the bivalves Thyasira flexuosa and Abra nitida, the polychaetes L. cingulata, Chaetozone and Glycera unicornis, the amphipod Harpinia antennaria. Thyasira flexuosa, H. antennaria and A. nitida were recorded in their highest abundance from sample stations within Faunal group F. Notably, Norway lobster Nephrops norvegicus was also recorded at two stations within Faunal group F (ST81 and ST109). It was distinct from the other Faunal groups due to the presence and abundance of the characterising species as well as the absence of the polychaete Paradoneis lyra, which distinguished it from Faunal group P and the scaphopoda Antalis entails, which distinguished it from Faunal group O. Faunal group F was allocated a preliminary biotope based on the infaunal data of SS.SMu.CSaMu.ThyNten: Thyasira spp. and Nuculoma tenuis in circalittoral sandy mud.
  6. Faunal group J comprised three sample stations (ST15, ST17, ST26) across the eastern section of the Proposed Development array area. Faunal group J was associated with slightly gravelly sand and gravelly sand sediments. It was characterised by E. pusillus, O. borealis, A. pygmaea, Nematoda, G. lapidum and Nemertea. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well the absence of the Decapoda Galathea intermedia, which distinguished it from Faunal group D and Mytilidae juveniles, which distinguished it from Faunal group C. Faunal group J showed lowest Bray-Curtis dissimilarity (71.79%) with Faunal group K with the top three species contributing 8.96% of dissimilarity due to the differing abundances of these species. Faunal group J was allocated a preliminary biotope based on the infaunal data of SS.SSa.CFiSa.EpusOborApri Echinocyamus pusillus, Ophelia borealis and Abra prismatica in circalittoral fine sand.
  7. Faunal group K comprised 13 sample stations (ST18, ST27, ST28, ST29, ST30, ST31, ST32, ST49, ST53, ST58, ST59, ST61, ST68) across the north and outside of the Proposed Development array area. Faunal group K was associated with slightly gravelly sand, gravelly sand and sandy gravel sediments. It was characterised by O. borealis, Abra juveniles, A. prismatica, E. pusillus, Thracioidea juveniles and Amphiuridae juveniles. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well as the lack of G. intermedia, which distinguished it from Faunal group D and Leptochiton, which distinguished it from Faunal group C. Faunal group K showed the lowest dissimilarity (71.79%) with Faunal group J. Faunal group K was allocated a preliminary biotope based on the infaunal data of SS.SSa.CFiSa.EpusOborApri. Sample stations ST49 and ST68 were reclassified to SS.SMx.OMx. due to the sediment type present, the high proportion of polychaetes, and the low abundance of E. pusillus and O. borealis.
  8. Faunal group M comprised three sample stations (ST23, ST57, ST63) from the north and outside of the Proposed Development array area. Faunal group M was associated with gravelly sand sediments. It was characterised by Astrorhiza, P. lyra, S. spinulosa, Nothria, Ophiuridae juveniles, Polycirrus and Scoloplos armiger. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well the absence of Amphiuridae juveniles, which distinguished it from Faunal group N, L and O. Faunal group M showed the least Bray-Curtis dissimilarity to Faunal group P with the top four species contributing 10.3% of dissimilarity due to the differing abundances of these species. Faunal group M was allocated a preliminary biotope based on the infaunal data of SS.SMx.OMx.PoVen.
  9. Faunal group N comprised 32 sample stations (ST03, ST06, ST08, ST09, ST10, ST13, ST14, ST16, ST19, ST21, ST22, ST24, ST35, ST37, ST40, ST41, ST42, ST43, ST46, ST48, ST51, ST55, ST60, ST62, ST64, ST72, ST78, ST74, ST92, ST93, ST95, ST112) from across the south and outside of the eastern section of the Proposed Development array area and across the western section of the Proposed Development array area. Faunal group N was associated with gravelly sand, slightly gravelly sand and sandy gravel sediments. It was characterised by Amphiuridae juveniles, A. filiformis, Spiophanes bombyx, Scoloplos armiger, Astrorhiza, Abra juveniles, Kurtiella bidentata and E. pusillus. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well the absence of H. norvegica, which distinguished it from Faunal group E and S. parapari, which distinguished it from Faunal group C. Faunal group N showed the lowest Bray-Curtis dissimilarity (71.18%) with Faunal group O, with the top 16 species contributing 32.03% of dissimilarity due to the differing abundances of these species. Faunal group N was allocated a preliminary biotope based on the infaunal data of SS.SMu.CSaMu.AfilMysAnit: Amphiura filiformis, Mysella bidentata and Abra nitida in circalittoral sandy mud. The overall community reflected this biotope, and the biotope description contains the Faunal group characterising species S. bombyx, S. armiger or E. pusillus however the sediments were generally coarser than are described for this biotope. Sample station ST92 was reclassified as SS.SMx.OMx due to the sediments present. Sample stations ST62 and ST95 were reclassified to SS.SSa.CFiSa.ApriBatPo due to the characterising species at these sample stations. ST21 was reclassified to SS.SMx.CMx.MysThyMx due to the characterising species at this sample station.
  10. Faunal group O comprised eight sample stations (ST12, ST34, ST91, ST73, ST79, ST97, ST104, ST105) from across the south of the Proposed Development array area and offshore section of the Proposed Development export cable corridor. Faunal group O was associated with slightly gravelly sand and muddy sand sediments. It was characterised by A. filiformis, Amphiuridae juvenile, T. flexuosa, Lagis koreni, S. bombyx and A. entails. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well as the absence of O. borealis and Thracioidea juvenile which distinguished it from Faunal group K. Faunal group O showed the lowest dissimilarity (71.18%) with Faunal group N. Faunal group O was allocated a preliminary biotope based on the infaunal data of SS.SMu.CSaMu.AfilNten based on the community present, however Nunculoma tenuis was not recorded in Faunal group O therefore this group represented a species poor version of this habitat.
  11. Faunal group P comprised eight sample stations (ST05, ST11, ST33, ST45, ST76, ST77, ST96, ST102) from across the south and outside of the Proposed Development array area and offshore section of the Proposed Development export cable corridor. Faunal group P was associated with slightly gravelly sand, gravelly sand and sandy gravel sediments. It was characterised by Astrorhiza, E. pusillus, Nemertea, Amphiuridae juveniles, P. lyra, S. bombyx and the bivalve Ennucula tenuis. It was distinct from the other Faunal groups due to the presence and abundance of these characterising species as well the absence of A. pygmaea, which distinguished it from Faunal group J and B. crenatus, which distinguished it from Faunal group I. Faunal group P showed least Bray-Curtis dissimilarity (74.49%) with Faunal group N with the top nine species contributing to 19.06% of dissimilarity due to the differing abundances of these species. Faunal group P was allocated a preliminary biotope based on the infaunal data of SS.SSa.OSa: Offshore circalittoral Sand. ST05 was reclassified as SS.SSa.OSa [Echinocyamus pusillus]: Echinocyamus pusillus dominated offshore circalittoral sand due to the high proportion of E. pusillus. Sample station ST45 was reclassified to SS.SMx.OMx.PoVen due to the sediment type present, the high proportion of polychaetes. Sample stations ST76 and ST77 were reclassified as SS.SMx.OMx due to the sediments present.
  12. Faunal group A (ST108), Faunal group B (ST83), Faunal group G (ST90), Faunal group H (ST94), Faunal group I (ST44), and Faunal group L (ST07) were represented by a single sample station each. Details of characterising species, sediment classification and geographic location are presented in Table 3.9   Open ▸ . Faunal group A was allocated a preliminary biotopes based on the infaunal data of SS.SSa.IFiSa.NcirBat: Nephtys cirrosa and Bathyporeia spp. in infralittoral sand. This sample stations showed clear separation from the other sample stations within the MDS plot ( Figure 3.11   Open ▸ ). Faunal group B was allocated a preliminary biotope based on the infaunal data of SS.SMx.OMx: Offshore circalittoral mixed sediments. Faunal group G was allocated a preliminary biotope based on the infaunal data of SS.SCS.CCS: Circalittoral course sediments. Faunal group H was allocated a preliminary biotope mosaic based on the infaunal data of SS.SMx.OMx.PoVen and SS.SSa.CFiSa.EpusOborApri, on the basis that it was located at the transition between two distinct areas of either biotope and contained the characterising taxa of both biotopes. Faunal group I was allocated a preliminary biotope based on the infaunal data of SS.SCS.CCS [Balanus crenatus]: Balanus crenatus dominated Circalittoral coarse sediments due to the sediment type and low number of taxa and individuals. Faunal group L was allocated a preliminary biotope based on the infaunal data of SS.SSa.OSa.
  13. When the analysis was repeated without juveniles, some sample stations within Faunal groups were split across new Faunal groups (e.g. Faunal group N was mostly split over three faunal groups with ST09, ST24, ST78 grouped with ST33 (Faunal group P) with a higher degree of similarity to each other than with the other sample stations in Faunal group N). This highlighted the importance of juveniles in grouping samples stations within the Faunal groups. The statistical analysis grouped the sample stations differently however it did not result in any different biotopes being allocated.
  14. The Faunal groups presented in the SIMPER analysis and the raw data were used to assign 15 preliminary biotopes within the Proposed Development benthic subtidal and intertidal ecology study area ( Table 3.9   Open ▸ ; Figure 3.11   Open ▸ ). Although S. spinulosa was a characterising species at Faunal group E, no aggregations qualifying as a reef forming structure were recorded. The full Annex I reef assessment is presented in Annex B: Annex I Reef Assessments. Ocean quahog A. islandica was also recorded in the benthic grabs; details are presented in section 3.4.8. The full SIMPER analysis results are presented in Annex C: Benthic Infaunal Data Multivariate Analysis Results.
  15. The east of the Proposed Development array area was dominated by SS.SMu.CSaMu.AfilMysAnit in the south and east and SS.SSa.CFiSa.EpusOborApri in the north. Small areas of SS.SSa.OSa and SS.SSa.Osa [Echinocyamus pusillus] were present in the south with small areas of SS.SMx.CMx.MysThysMx, SS.SMuCSaMuAfilNten and SS.SCS.CCS [Balanus crenatus] in the central section. The west of the Proposed Development array area was dominated by SS.SMu.CSaMu.AfilMysAnit in the south and SS.SMx.OMx.PoVen in the west and central sections. There were small areas of SS.SBR.PoR.SspiMx in the south, SS.SMx.OMx in the central section and SS.SMuCSaMuAfilNten in the south. The Proposed Development export cable corridor was dominated by SS.SMu.CSsMu.ThyNten with SS.SMu.CSaMu.AfilMysAnit and SS.SSa.OSa near the Proposed Development array area ( Figure 3.12   Open ▸ ).
FFBC MPA
  1. The FFBC MPA overlaps with the western edge and south-east sections of the Proposed Development benthic subtidal and intertidal ecology study area. Preliminary infaunal biotopes recorded from within the section of the FFBC MPA overlapping with the east of the Proposed Development array area included: SS.SMu,CSaMu.AfilMysAnit, SS.SSa.CFiSa.EpusOborApri, SS.SSa.OSa and SS.SSa.OSa [Echinocyamus pusillus]. Preliminary infaunal biotopes recorded from within the section of the FFBC MPA overlapping with the west of the Proposed Development array area included: SS.SMx.OMx.PoVen, SS.SMu,CSaMu.AfilMysAnit, SS.SBR.PoR.SspiMx, SS.SSa.CFiSa.ApriBatPo, SS.SSa.OSa and SS.SSa.CFiSa.EpusOborApri ( Figure 3.12   Open ▸ ).

 

Figure 3.11:
3D MDS Plot of Infaunal Communities from Grab Samples (with biotope Groupings) within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.11: 3D MDS Plot of Infaunal Communities from Grab Samples (with biotope Groupings) within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

 

Table 3.9:
Infaunal Biotopes Identified from Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Table 3.9:  Infaunal Biotopes Identified from Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.12:
Preliminary Infaunal Biotopes Recorded from Grab Samples Across the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.12:  Preliminary Infaunal Biotopes Recorded from Grab Samples Across the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Univariate analysis

  1. The following univariate statistics were calculated for each benthic infaunal grab sample station: number of species (S), abundance (N), ash free dry mass in grams (g), Margalef’s index of Richness (d), Pielou’s Evenness index (J’), Shannon-Wiener Diversity index (H’) and Simpson’s index of Dominance (λ). The mean of each of these indices was then calculated for each of the preliminary infaunal biotopes identified from the infaunal data and these are summarised in Table 3.10   Open ▸ with univariate statistics for individual sites presented in Annex D: Benthic Infaunal Data Univariate Analysis Results.
  2. The univariate statistics indicate that the SS.SBR.PoR.SspiMx biotope, had the highest number of taxa (76± 11.31). The biotope SS.SSa.IFiSa.NcirBat, which was represented by one sample station had the lowest number of taxa (17). The highest mean number of individuals was recorded in SS.SMx.OMx (293.8± 560.31; Table 3.10   Open ▸ ); this was expected as it contained one of the highest number of taxa. The high number of individuals in this biotope was due to high abundances of D. grossularia, L. cingulata and S. spinulosa at ST83. The lowest mean number of individuals (39) was recorded in the SS.SSa.IFiSa.NcirBat biotope which is aligned with the low number of taxa recorded within this biotope.
  3. The highest mean diversity score of all the identified communities was associated with the biotope SS.SBR.PoR.SspiMx (d = 13.50 ± 1.09and H’ = 3.72 ± 0.20) which was expected as this biotope had the highest number of taxa. The SS.SMx.OMx.PoVen biotopes had the next highest mean diversity score (d = 12.10± 3.10, H’ = 3.70± 0.30). The lowest diversity recorded was associated with the SS.SSa.IFiSa.NcirBat biotope. This was expected as this biotope had the lowest number of taxa and individuals. The SS.SSa.IFiSa.NcirBat biotope was recorded at one of the most inshore samples within the Proposed Development benthic subtidal and intertidal ecology study area and as such was likely to have been exposed to greater disturbance from wave action than those communities in the deeper waters, potentially explaining the reduced diversity in these communities. This biotope is known to have considerably reduced faunal diversity compared to less disturbed biotopes (JNCC, 2021). Overall, the coarse and mixed sediment habitats had higher diversity than the sandy sediment habitats; this was expected due to the greater habitat complexity of coarse sediments supporting a higher number of species.
  4. Pielou’s evenness scores (J’) and the Simpson’s index of Dominance (λ) scores varied across the biotopes. Values of J’ were highest for SS.SMu.CsaMu.ThyNten, SS.SSa.Osa, SS.SMx.Omx.PoVen, SS.Ssa.IfiSa.NcirBat (J’= 0.91). This indicated an even distribution of abundances among taxa and that these biotopes were not dominated by a high number of individuals within a small number of species. Values of J’ were lowest at SS.SCS.CCS [Balanus crenatus] which indicated that this biotope was more dominated by a high number of individuals within a small number of taxa than the other biotopes (e.g. S. spinulosa). The biotopes SS.SBR.PoR.SspiMx and SS.SMx.OMx.PoVen and SS.SCS.CCS had slightly lower values for λ compared with the other biotopes. This indicated that these biotopes were not dominated by a small number of species.

 

Table 3.10:
Mean (± Standard Deviation) Univariate Statistics for the Preliminary Infaunal Benthic Biotopes

Table 3.10:  Mean (± Standard Deviation) Univariate Statistics for the Preliminary Infaunal Benthic Biotopes

 

  1. Figure 3.13   Open ▸ to Figure 3.15   Open ▸ show the mean number of taxa, individuals and biomass for each of the major faunal groups (i.e. Annelida, Crustacea, Mollusca, Echinodermata and Other) in each of the biotopes identified, within the Proposed Development benthic subtidal and intertidal ecology study area, from the benthic infaunal grabs. The biotope SS.SMx.OMx contained the highest number of individuals, which is aligned with the univariate statistics in Figure 3.10   Open ▸ for the single station represented by this biotope. The high number of individuals in the SS.SMx.OMx biotope were dominated by Annelida and Other taxa, as mentioned before this was due to the high abundances of D. grossularia, L. cingulata and S. spinulosa. The biotopes SS.SBR.PoR.SspiMx, SS.SCS.CCS [Balanus crenatus], SS.SCS.CCS and SS.SMx.OMx.PoVen also had high numbers of individuals. Soft sediment habitats: SS.SMu.CSaMu.AfilMysAnit, SS.SMu.CSaMu.AfilNten, SS.SMu.CSaMu.ThyNten and SS.SSa.IFiSa.NcirBat generally showed low numbers of individuals. Crustacea and Annelida made up a high percentage of the individuals in each biotope. Other taxa were generally poorly represented across all biotopes, making up the smallest proportion of individuals in each biotope with the exception of SS.SMx.OMx.PoVen and SS.SMx.OMx.
  2. As shown in Figure 3.14   Open ▸ , the proportions of the number of taxa in each major taxonomic groups are similar across the biotopes, with Crustacea and Annelida making up the highest proportion of the taxa present in each biotope. All major taxonomic groups were represented in all biotopes. The dominance of Crustacea in the number of taxa in each biotope is greater than the dominance of Crustacea in the number of individuals for all biotopes, highlighting that each of the Crustacea taxa are represented by a small number of individuals.
  3. Biomass was highest at the biotopes SS.SSa.CFiSa.EpusOborApri and SS.SSa.IFiSa.NcirBat which were dominated by Mollusca and Echinodermata respectively. This may be due to the high abundance of the mollusc A. prismatica in SS.SSa.CFiSa.EpusOborApri and the presence of a single adult specimen of E. cordatum in SS.SSa.IFiSa.NcirBat. Annelida made up a small proportion of the total biomass in each biotope, which is expected due to the small size of Annelida. Biomass per taxonomic group for each sample station is presented in Annex E: Benthic Infaunal Contribution of Biomass to Gross Taxonomic Groups.

Figure 3.13:
Mean Abundance of Individuals (per 0.1 m2) per Taxonomic Group for Each Infaunal Biotope

Figure 3.13:  Mean Abundance of Individuals (per 0.1 m2) per Taxonomic Group for Each Infaunal Biotope

Figure 3.14:
Mean Number of Taxa (per 0.1 m2) per Taxonomic Group Identified for Each Infaunal Biotope

Figure 3.14:  Mean Number of Taxa (per 0.1 m2) per Taxonomic Group Identified for Each Infaunal Biotope

Figure 3.15:
Mean Biomass (per 0.1 m2) per Taxonomic Group for each Infaunal Biotope

Figure 3.15:  Mean Biomass (per 0.1 m2) per Taxonomic Group for each Infaunal Biotope

3.4.6.    Results - Epifaunal Analysis

Seabed imagery

  1. The sediments recorded in the seabed imagery largely comprised of subtidal coarse sediments, especially at the offshore sample stations within the Proposed Development array area. Softer sediments (i.e. sands and muds) were more common across the Proposed Development export cable corridor, although circalittoral rock and subtidal coarse sediments were recorded at some of the furthest inshore sample stations. In general, high numbers of epifaunal species were recorded in association with the coarser sediments (coarse and mixed sediments). Epifaunal species recorded were dominated by Crustaceans and Cnidarians with low numbers of Molluscs and Polychaetes, however this may be due to the nature of video sampling, as most polychaetes are infaunal species therefore would not be visible to DDV sampling. The bryozoan F. foliacea was among the most abundant species and was associated with every sediment type with the exception of mud sediments (Error! Reference source not found.).
  2. Sample stations with rock substrate were associated with the presence of the hydroid Nemertesia ramosa, the squat lobster M. rugosa, the common star fish A. rubens and the sea urchin Echinus esculentus. Samples with coarse and mixed sediments were associated with the presence of dead man’s fingers Alcyonium digitatum, acorn barnacles Semibalanus balanoides, A. rubens and the polychaete Spirobranchus sp. Sand sediments were associated with the presence of dead man’s fingers and polychaete tube worms. Mud sediments were associated with the presence of the seapens P. phosphorea and V. mirabilis, as well as the gastropod Turritella sp.Taxa that were recorded at a single station included true crabs Goneplax rhomboides (ST99) and N. puber (ST107; Figure 3.17   Open ▸ ), sea star Crossaster papposus (ST50) and brittlestar Ophiura albida (ST96).

Figure 3.16:
Flustra foliacea on Mixed Sediments at ST01

Figure 3.16: Flustra foliacea on Mixed Sediments at ST01

Figure 3.17:
Necora puber, Alcyonium digitatum and Echinus esculentus on Coarse Sediments at ST107

Figure 3.17: Necora puber, Alcyonium digitatum and Echinus esculentus on Coarse Sediments at ST107


Summary statistics

  1. The epifaunal data that were recorded as present/absent, and therefore removed from the infaunal grab data analysis, were combined with the epifaunal data from the DDV. A total of 147 taxa and 10 categories of burrows and waste casts were recorded from the 112 infaunal grabs and DDV within the Proposed Development benthic subtidal and intertidal ecology study area. Of the total 147 taxa, none were recorded across all sample stations however F. foliacea was recorded at 74 (50%) sample stations and faunal turf was recorded at 89 (60%) sample stations. Tube worms were also relatively common, with 73 sample stations recording S. spinulosa and/or Spirobranchus sp. A total of 72 taxa were recorded at only one sample station, these were distributed across the Proposed Development benthic subtidal and intertidal ecology study area. Sample station ST90 recorded the highest number of epifaunal taxa, with ST20 recording the highest number of burrows and waste casts. The majority of the burrows recorded were 6 -9 cm and from sample stations within the Proposed Development export cable corridor.

Multivariate Community Analysis

  1. The results of the cluster analysis, SIMPROF test and SIMPER analysis were used, together with the raw untransformed data, to assign preliminary epifaunal biotopes to sample stations based on the dataset which combined the DDV data and the epibenthic component of the grabs. In several instances, clusters that were identified as significantly different from each other in the SIMPROF tests were assigned the same biotope code. This was based on a review of the SIMPER results which indicated that the differences between the groups could be explained by differences in abundances of characterising species rather than the presence/absence of key species. Full results of the multivariate analysis are presented in Annex F: Benthic Grab and DDV Epifaunal Data Multivariate Analysis Results.
  2. The results of the hierarchical cluster analysis of the square root transformed epifaunal dataset together with the SIMPROF test identified 13 Faunal groups that were statistically dissimilar, based on the SIMPROF test ( Figure 3.18   Open ▸ ). The 3D MDS plot is presented in Figure 3.19   Open ▸ and the low stress value (0.13) indicates that this is a good representation of the data. The 2D MDS plot has not been presented as the 3D MDS plot presents a clearer representation of the data. Faunal groups E, G, H and M contained the majority of the sample stations, with the other faunal groups represented by a few or a single sample station.
  3. Faunal group A (ST29) showed distinct clustering away from the other Faunal groups. Faunal groups I, J, K, L and M showed a higher degree of similarity with each other than they do to the other Faunal groups. Faunal groups I (ST21), J (ST108), K (ST16) and L (ST73) were all single sample station Faunal groups and Faunal group M contained 17 sample stations, mainly from within the Proposed Development export cable corridor. Faunal group D showed tight clustering with a Bray-Curtis similarity of 60.44%. Faunal group H contained the highest number of sample stations (51) with Bray-Curtis similarity of 40.67%. Multivariate analysis was also run on the epifaunal data without the burrows and waste casts to determine the influence of these categories. The SIMPROF test identified 16 Faunal groups that were statistically dissimilar. The difference in Faunal groups is discussed in the following paragraphs.
  4. Faunal group E (ST01, ST02, ST04, ST20, ST33, ST34, ST38, ST39, ST40, ST45, ST56, ST65, ST67 ST69, ST75, ST100, ST101, ST103, ST110) comprised sample stations located across the centre of the Proposed Development benthic subtidal and intertidal ecology study area and was associated with mixed sediments (gravelly sand, slightly gravelly sand and sandy gravel). Characterising taxa included faunal turf, Spirobranchus sp., F. foliacea and branching hydroids. Faunal group E showed high Bray-Curtis dissimilarity with Faunal group M (94.86%). Faunal group M did not record Spirobranchus sp., F. foliacea or branching hydroids which were present in Faunal group E. Faunal group E showed low Bray-Curtis dissimilarity with Faunal groups G (67.70%) and Faunal group H (67.55%). Faunal group E did not record Follicundidae, Escharella ventricose, Escharella immersa or Phoronis ovalis which were present in Faunal group G. Faunal group E recorded higher abundances of Spirobranchus sp., branching hydroids and acorn barnacles than were recorded in Faunal group H. Faunal group E was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SCS.CCS.

Figure 3.18:
Dendrogram of Epifaunal Communities within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.18:  Dendrogram of Epifaunal Communities within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

  1. Faunal group G (ST15, ST36, ST47, ST50, ST52, ST54, ST61, ST66, ST70, ST71, ST83, ST94) comprised sample stations located across the Proposed Development benthic subtidal and intertidal ecology study area and was associated with gravelly sand, sandy gravel and muddy sandy gravel sediments. Characterising taxa included the polychaete Spirobranchus sp., the anthozoan A. digitatum, the bryozoans F. foliacea, Escharella ventricosa, Escharella immersa, Alcyonidium parasiticum, and Amphiblestrum auritum, the hydrozoa Sertulariidae, the heterotrichida Folliculinidae, Phoronis ovalis, the echinoderm A. rubens, branching hydroids, faunal turf and Porifera. Faunal group G showed high Bray-Cutis dissimilarity with Faunal group M (96.98%) due to the presence of Spirobranchus sp., A. digitatum, F. foliacea, Folliculinidae and E. ventricosa in Faunal group M which were absent from Faunal group G. Faunal group G showed the lowest Bray-Curtis dissimilarity with Faunal group F (65.61%) as both Faunal groups recorded T. thuja, F. foliacea, Folliculinidae and bushy hydroids. Faunal group G was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SCS.CCS.
  2. Faunal group H (ST03, ST05, ST06, ST07, ST08, ST09, ST10, ST11, ST13, ST14, ST17, ST18, ST19, ST22, ST23, ST24, ST25, ST26, ST27, ST28, ST30, ST31, ST32, ST35, ST37, ST41, ST42, ST43, ST44, ST46, ST49, ST51, ST53, ST55, ST57, ST58, ST59, ST60, ST62, ST63, ST64, ST68, ST72, ST74, ST76, ST77, ST91, ST92, ST93, ST95, ST112) comprised sample stations located across the Proposed Development benthic subtidal and intertidal ecology study area and was associated with mixed sediments (gravelly sand, slightly gravelly sand and sandy gravel). Characterising taxa included faunal turf, Folliculinidae, F. foliacea and A. digitatum with faunal turf and Folliculinidae making up nearly 50% of the Bray-Curtis similarity within this group. Faunal group H showed high Bray-Curtis dissimilarity with Faunal group M (90.82%) due to the absence of Folliculinidae and F. foliacea in Faunal group M but presence in Faunal group M. In addition, 1 cm and 2 cm burrows were recorded in higher abundances in Faunal group M compared to Faunal group H. Faunal group H showed the lowest Bray-Curtis dissimilarity with Faunal group E (67.55%) as both Faunal groups recorded Spirobranchus sp., A. digitatum, Balanomorpha, Sertulariidae, M. rugosa and branching hydroids. Faunal group H was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SCS.CCS. 
  3. Faunal group F (ST96, ST90, ST102) comprised sample stations located from the south of the eastern section of the Proposed Development array area and was associated with gravelly sand sediments. Characterising taxa included A. parasiticum, A. digitatum, branching hydroids, bushy hydroids, faunal turf and the hydrozoa Thuiaria thuja. Faunal group F showed high Bray-Curtis dissimilarity with Faunal group M (92.60%) due to the presence of A. parasiticum, A. digitatum, branching hydroids and bushy hydroids in Faunal group F that were absent from Faunal group M. Faunal group F showed the lowest Bray-Curtis dissimilarity with Faunal group E (65.59%) as both Faunal groups recorded A. parasiticum, T. thuja, F. foliacea, A. digitatum, Ophiothrix fragilis/Ophiocomina nigra and bushy hydroids. Faunal group F was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SCS.CCS. A review of the results of the SIMPER analysis showed that Faunal groups E, F, G and H were only distinct from each other due to differing abundances of similar characterising species (faunal turf, A. digitatum, F. foliacea and branching hydroids) rather than the presence/absence of key species.
  4. Faunal group M (ST12, ST78, ST79, ST80, ST81, ST82, ST85, ST86, ST87, ST88, ST97, ST98, ST99, ST104, ST105, ST106, ST109) comprised sample stations located within the Proposed Development export cable corridor and was associated with muddy sand. Characterising features included burrows of 1-5 cm with burrows of 1 cm providing 42.06% of similarity between sample stations in Faunal group M. Several of the sample stations within Faunal group M recorded the seapens P. phospohorea and V. mirabilis. Faunal group M showed high Bray-Curtis dissimilarity with Faunal group G, as discussed above for Faunal group G. Faunal group M recorded lower Bray-Curtis dissimilarity with Faunal group H as they both contained the 1 cm and 2 cm burrows as characterising features. When the multivariate analysis was repeated without the burrows data, Faunal group M was split among the Faunal groups, however ST79, ST81, ST82, ST85, ST88, ST97, ST98, ST99, ST104, ST106, ST109 remained grouped together as one Faunal group. Faunal group M was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SMu.CFiMu.SpnMeg. ST12 had a lower number of burrows and did not recorded and seapens therefore was allocated a separate biotope of SS.SSa.CMuSa. The sample stations within this Faunal Group are clearly shown in the MDS plot ( Figure 3.19   Open ▸ ) as clustering away from the other Faunal groups.
  5. Faunal group D (ST84, ST89, ST107) comprised sample stations located within and outside the Proposed Development export cable corridor and was associated with moderate energy infralittoral rock. Characterising taxa included encrusting orange sponges, encrusting red calcareous algae, encrusting yellow sponges and faunal turf. Faunal group D showed high Bray-Curtis dissimilarity with Faunal group M (95.39%) due to the absence of Faunal group D’s characterising species in this Faunal group as well as the absence of 1 cm burrows which were recorded in Faunal group M. Both Faunal groups recorded faunal turf, M. rugosa and prawns/shrimps/mysids. Faunal group D showed the lowest Bray-Curtis dissimilarity with Faunal group E (62.15%) as both Faunal groups recorded M. rugosa, A. digitatum, Sertularidae, Balanomorpha, branching hydroids and erect hydroids. When the multivariate analysis was run without the burrows data, ST84 was its own Faunal group separate from the other stations within Faunal group D, highlighting the importance of the burrows in grouping these sample stations. Faunal group D was allocated a preliminary biotope based on the epifaunal DDV and grab data of: CR.MCR.EcCr. The sample stations within this Faunal Group are clearly shown in the MDS plot ( Figure 3.19   Open ▸ ) as clustering together with the closest similarity with the sample stations classified as SS.CSS.CCS; a similar hard substrate habitat.
  6. Faunal group A (ST29), Faunal group B (ST111), Faunal group C (ST48), Faunal group I (ST21), Faunal group J (ST108), Faunal group K (ST16) and Faunal group L (ST73) were each represented by a single sample station. Faunal group A was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SSa.OSa: Offshore circalittoral sand. This sample station is clearly shown in the MDS plot ( Figure 3.19   Open ▸ ) as clustering away from the other sample stations. Faunal group C was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SCS.CCS: Circalittoral coarse sediment. Faunal group I, Faunal group K and Faunal group L were allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SSa.CMuSa. Faunal group J was allocated a preliminary biotope based on the epifaunal DDV and grab data of SS.SSa.CFiSa. This sample station is clearly shown in the MDS plot ( Figure 3.19   Open ▸ ) as clustering away from most of the other sample stations with the closest similarity to sample stations classified as SS.SSa.CMuSa; a similar fine soft sediment habitat.

 

Figure 3.19:
3D MDS Plot of Epifaunal Communities from Grab Samples (with biotope Groupings) within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.19: 3D MDS Plot of Epifaunal Communities from Grab Samples (with biotope Groupings) within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

 

  1. Multivariate analysis was also run separately on the epifaunal data recorded as percentage cover. The SIMPROF test identified 20 Faunal groups that were statistically dissimilar ( Figure 3.20   Open ▸ ). The majority of the sample stations were placed in one Faunal group by the percentage cover data, this included sample stations from epifaunal data Faunal group D, E, F and G. These sample stations were grouped due to their similar percentage cover of faunal turf, Spirobranchus sp. and acorn barnacles. Faunal turf provided 56.14% Bray Curtis similarity between sample stations. The majority of the sample stations within Faunal group E recorded 0.01-5.6% cover of F. foliacea and 1.4-10% cover of Spirobranchus sp. Sample stations within Faunal group F were characterised by 0.01-0.9% cover of A. digitatum and 0.88-10.7% cover of faunal turf. Sample stations within the epifaunal enumerated taxa Faunal group H were not grouped together in the epifaunal percentage cover Faunal group data analysis. They were split between the two largest epifaunal percentage cover Faunal groups, interspersed with sample stations from other Faunal groups in the epifaunal enumerated taxa. Multivariate analysis of the percentage cover data placed ST111, ST109, ST108, ST106, ST104, ST99, ST98, ST97, ST88, ST86, ST85, ST82, ST81, ST79, ST21, ST16 and ST29 in single station Faunal groups ( Figure 3.20   Open ▸ ). This is similar to the enumerated epifaunal data which placed ST29 as Faunal group A, ST111 as Faunal group B, ST48 as Faunal group C, ST21 as Faunal group I, ST108 as Faunal group J, ST16 as Faunal group K and ST73 as Faunal group L. Sample stations ST21, ST108 and ST16 as well as a large number of sample stations from Faunal group M (ST79, ST82, ST85, ST86, ST88, ST97, ST98, ST99, ST104, ST106, ST109) were placed in their own single sample Faunal group due to the lack of epifaunal percentage cover data. This was expected due to the muddy sediment at these sample stations.
  2. The Faunal groups presented in the SIMPER analysis and the raw data were used to assign five preliminary epifaunal biotopes within the Proposed Development benthic subtidal and intertidal ecology study area ( Table 3.11   Open ▸ ; Figure 3.21   Open ▸ ). Figure 3.21   Open ▸ presents the preliminary epifaunal biotopes assigned across the Proposed Development benthic subtidal and intertidal ecology study area from the analyses of the epifaunal component of the grab data and DDV. The biotope SS.SCS.CCS was recorded across the Proposed Development array area, with a small area of SS.SSa.OSa just outside the north of the eastern section of the Proposed Development array area and a small area of SS.SSa.CMuSa in the centre of the eastern section of the Proposed Development array area. The Proposed Development export cable corridor was also dominated by SS.SCS.CCS and SS.SMu.CFiMu.SpnMeg with areas of CR.MCR.ECcR in the nearshore subtidal area ( Figure 3.21   Open ▸ ).
FFBC MPA
  1. All sample stations within the FFBC MPA were allocated the preliminary biotope SS.SCS.CCS, with the exception of ST12, which was allocated SS.SSa.CMuSa and was located within the eastern section of the FFBC MPA ( Table 3.11   Open ▸ ).

 

Figure 3.20:
Dendrogram of Epifaunal Communities Recorded as Percentage Cover within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.20: Dendrogram of Epifaunal Communities Recorded as Percentage Cover within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.21:
Preliminary Epifaunal Biotopes Identified from DDV and Epifaunal Component of the Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Figure 3.21: Preliminary Epifaunal Biotopes Identified from DDV and Epifaunal Component of the Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

Table 3.11:
Epifaunal Biotopes Identified from DDV and Epifaunal Component of the Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area (from DDV and Grab Data)

Table 3.11:  Epifaunal Biotopes Identified from DDV and Epifaunal Component of the Grab Samples within the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area (from DDV and Grab Data)

 

Univariate analysis

  1. The following univariate statistics were calculated for the combined epibenthic dataset (i.e. epibenthic components of the grabs and DDV data) for each sample station: number of species (S), abundance (N), ash free dry mass in grams (g), Margalef’s index of Richness (d), Pielou’s Evenness index (J’), Shannon-Wiener Diversity index (H’) and Simpson’s index of Dominance (λ). The mean of each of these indices was then calculated for each of the biotopes identified from the epifaunal data and these are summarised in Table 3.12   Open ▸ , with univariate statistics for individual sites presented in Annex G: Benthic Grab and DDV Epifaunal Data Univariate Analysis Results.
  2. The biotope CR.MCR.EcCr had the highest number of taxa (14.25 ± 5.56). The biotopes SS.SSa.IFiSa and SS.SSa.OSa were represented by a single sample station each and had particularly low number of taxa ( Table 3.12   Open ▸ ). The highest mean number of individuals was recorded in CR.MCR.EcCr (11.62 ± 3.96; Table 3.12   Open ▸ ); this was expected due to the nature of hard sediments. The high number of individuals in this biotope was due to the high abundance of algae and sponge species as well as faunal turf. The lowest mean number of individuals was recorded in biotope SS.SSa.OSa as this sample station only recorded O. ophiura. Overall, the highest number of individuals and taxa were recorded at biotopes with hard substrate and the lowest numbers were recorded in sand sediment habitats.
  3. The highest mean diversity score of all the identified communities was identified in the biotope CR.MCR.EcCr (d = 5.48 ± 1.76 and H’ = 2.41±0.42), which was expected, as this biotope had the highest number of taxa and was characterised by hard substrate. The biotope SS.SCS.CCS had the next highest mean diversity score (d = 4.91± 1.78, H’ = 2.20 ± 1.53). The biotopes SS.SSa.IFiSa and SS.SSa.OSa recorded zero for diversity, this was expected as only a single species was recorded in association with SS.SSa.OSa and only burrows were associated with SS.SSa.IFiSa. Overall, the highest diversity was recorded at biotopes with hard substrate and the lowest was recorded in sand sediment habitats.
  4. Pielou’s evenness scopes (J’) scores varied across the biotopes, where these indices were able to be calculated. J’ was 0.94 and 0.93 at CR.MCR.EcCr and SS.SCS.CCS respectively however it was zero at SS.SSa.IFiSa and SS.SSa.OSa; indicating a very low evenness of distribution of abundances among taxa in these biotopes. This was expected, as only a single species was recorded in association with SS.SSa.OSa and only burrows were associated with SS.SSa.IFiSa. The Simpson’s index of Dominance (λ) was highest at SS.SSa.IFiSa and SS.SSa.OSa, indicating that these biotopes were dominated by a small number of taxa. Simpson’s index of Dominance was lowest at CR.MCR.EcCr indicating that this biotope had an even distribution of taxa.

 

Table 3.12:
Mean (± Standard Deviation) Univariate Statistics for Epifaunal Biotopes (from DDV and Grab Data)

Table 3.12: Mean (± Standard Deviation) Univariate Statistics for Epifaunal Biotopes (from DDV and Grab Data)

 

Epibenthic trawl analysis

Summary
  1. A total of 69 taxa were recorded from the 15 epibenthic trawls undertaken across the Proposed Development benthic subtidal and intertidal ecology study area. Of these, nine taxa were colonial or taxa whose abundance could not be enumerated, and therefore were recorded as present (P). These taxa were assigned a nominal abundance of 1, where present, for the purposes of the multivariate analysis. One Nudibranchia egg was recorded in BT14 which was removed from the statistical analysis. Twenty-one of the taxa were bony fish and represented 553 individuals. As fish taxa are highly mobile, they were removed from the statistical analysis but are discussed in paragraph 184. A total of 5,362 individuals representing 47 taxa were recorded across the Proposed Development benthic subtidal and intertidal ecology study area. Of these, juveniles accounted for 46 individuals from two taxa.
  2. Of the 47 total taxa throughout the Proposed Development subtidal and intertidal ecology study area, none were observed at all stations. The brown shrimp C. crangon was observed in the highest abundances at BT15, BT17 and BT18 within the Proposed Development export cable corridor; in total, C. crangon made up 51% of individuals recorded across all trawls. A total of eight taxa (17%) were recorded as only one individual. These rarely recorded taxa were distributed across the Proposed Development benthic subtidal and intertidal ecology study area, however four of the eight were recorded in BT09 in the centre of the Proposed Development benthic subtidal and intertidal ecology study area.
  3. As previously discussed, nine taxa were recorded only as present; these taxa were dominated by Anthozoa and Hydrozoa. Epifauna/colonial/encrusting taxa across the Proposed Development benthic subtidal and intertidal ecology study area included: one Nudibranchia egg, the bryozoan F. foliacea and the polychaete Spirobranchus sp. F. foliacea was recorded in the greatest number of trawls; present in 11 out of the 15. The hydrozoan T. thuja was only present in BT09 and the anthozoan Actiniaria was only recorded in BT14, BT17 and BT18 across the Proposed Development export cable corridor.
  4. Initially the dataset was divided into the five major taxonomic groups: Annelida (Polychaeta), Crustacea, Mollusca, Echinodermata and 'Others'. The 'Other' group comprised of:
  • three taxa of Anthozoa (Actiniaria, Adamsia palliata and A. digitatum);
  • three taxa of Hydrozoa (Hydrozoa, Sertulariidae and T. thuja);
  • one taxa of Bryozoa (F. foliacea); and
  • one taxa of Ctenophora (Pleurobrachia pileus).
    1. The absolute and proportional contributions of these five taxonomic groups to the overall community structure is summarised in Table 3.13   Open ▸ .

 

Table 3.13:
Contribution of Gross Taxonomic Groups Recorded in the Epibenthic Trawls

Table 3.13: Contribution of Gross Taxonomic Groups Recorded in the Epibenthic Trawls

 

  1. Across the Proposed Development benthic subtidal and intertidal ecology study area, the epibenthic trawl communities were generally dominated by Crustacea (n=3,961) which contributed 73.87% to the total number of individuals ( Table 3.13   Open ▸ ). Number of taxa was also dominated by Crustacea which made up 40.42% of the total taxa. At individual stations, gross taxonomic group dominance reflected the whole survey dominance results with crustacea dominating 11 (73%) benthic trawls. All other trawls were dominated by Echinodermata with the exception of BT17 which was dominated by Other taxa, specifically 200 individuals of P. pileus.
  2. The most abundant taxonomic group was Crustacea, which included the most abundant individual, C. crangon and the second most abundant individual Pandalidae; the highest abundances of both these taxa were recorded in BT11, BT12, BT14, BT15, BT16, BT17, BT18. The Echinodermata A. rubens and the Ctenophora P. pileus were recorded in high abundances. In general, epibenthic trawls in the Proposed Development export cable corridor recorded in higher number of individuals than those across the Proposed Development array area; BT18 recorded the highest number of individuals (1,294). However, number of taxa recorded was relatively evenly distributed across the Proposed Development benthic subtidal and intertidal ecology study area, with BT12 recording the highest number of taxa (21) and BT11 and BT13 both with 19 taxa.
  3. The most abundant fish recorded in the trawls were common dab Limanda (167 individuals), long rough dab Hippoglossoides platessoides (56 individuals), lesser sandeel Ammodytes tobianus (47 individuals) and gobies Pomatoschistus sp (51 individuals). This was consistent with the infaunal data which also recorded lesser sand eel (section 3.4.5). Lesser sandeel, common dab and long rough dab were recorded in trawls across the Proposed Development benthic subtidal and intertidal ecology study area. Pomatoschistus sp. was only recorded in trawls at BT14, BT16 and BT18 within the Proposed Development export cable corridor and nearshore area of the Proposed Development benthic subtidal and intertidal ecology study area, with most individuals recorded at BT18. Two four-bearded rockling Enchelyopus cimbrius and angler fish Lophius piscatorius were recorded across all trawls.
  4. Horse mussel M.modiolus was recorded in five of the benthic trawls (BT01, BT04, BT05, BT09, BT11). They were recorded in low numbers (<4 individuals) in each of these trawls with the exception of BT09 which recorded 31 individuals. Further information of the fish and shellfish species in the Proposed Development benthic subtidal and intertidal ecology study area is presented in volume 3, chapter 9.1.