Cumbria Coast Marine Conservation Zone (MCZ) Subtidal Characterisation Report 2015

MPA Monitoring Programme

Contract Reference: MB0129 Report Number: 3 Version: 4 Date: 18/01/2019

Project Title: Marine Protected Areas Monitoring Programme Report No 3. Title: Cumbria Coast MCZ Subtidal Characterisation Report Defra Project Code: MB0129 Defra Contract Manager: Carole Kelly

Funded by: Department for Environment, Food and Rural Affairs (Defra) Marine Science and Evidence Unit Marine Directorate Nobel House 17 Smith Square London SW1P 3JR

Authorship

David Clare Centre for Environment, Fisheries and Aquaculture Science (Cefas) [email protected]

Simeon Archer Centre for Environment, Fisheries and Aquaculture Science (Cefas) [email protected]

Acknowledgements

We thank Dr Joanna Murray for reviewing earlier drafts of this report.

Disclaimer: The content of this report does not necessarily reflect the views of Defra, nor is Defra liable for the accuracy of information provided, or responsible for any use of the reports content. Although the data provided in this report have been quality assured, the final products - e.g. habitat maps – may be subject to revision following any further data provision or once they have been used in SNCB advice or assessments.

Cefas Document Control

Title: Cumbria Coast Marine Conservation Zone Subtidal Characterisation Report

Submitted to: Marine Protected Areas Survey Co-ordination & Evidence Delivery Group Date submitted: August 2018 Project Manager: Sue Ware Report compiled by: David Clare and Simeon Archer Quality control by: Joanna Murray, Tammy Noble-James and Sue Ware Approved by & date: Silke Kröger, 23/08/2018 Version: 4

Version Control History Author Date Comment Version Clare & Archer 21/03/2017 Submitted for MPAG & external review V1 Clare & Archer 10/05/2018 Comments applied & rebranded as V2 characterisation report. Submitted for 2nd round of review. Clare & Archer 12/12/2018 Comment applied from 2nd round of review V3 Clare & Archer 18/01/2019 QA ahead of final submission V4

Contents Contents ...... i Tables ...... ii Figures ...... ii Executive Summary ...... 1 1 Introduction ...... 2 1.1 Aims and objectives ...... 4 2 Sample acquisition and processing ...... 5 2.1 Sampling design ...... 5 2.2 Data acquisition and processing ...... 6 2.2.1 Drop-down imagery ...... 6 2.2.2 Grab samples ...... 6 2.3 Data preparation and analysis...... 7 2.3.1 Sediment sample analysis ...... 7 2.3.2 Epifaunal data ...... 7 2.3.3 Macroinfaunal data ...... 7 3 Results ...... 9 3.1 Particle Size Distribution ...... 9 3.2 Broadscale Habitats ...... 10 3.3 Biological community analysis...... 12 3.3.1 A5.2 Subtidal sand ...... 12 3.3.2 A5.1 Subtidal coarse sediment ...... 15 3.3.3 A5.3 Subtidal mud ...... 16 3.4 Habitat Features of Conservation Importance ...... 17 3.4.1 Blue Mussel (Mytilus edulis) Beds ...... 17 3.4.2 Other Habitat FOCI ...... 17 3.4.3 Species Features of Conservation Importance ...... 17 3.5 Non-indigenous species ...... 17 4 Discussion ...... 18 5 References ...... 20 Annex 1. Macroinfauna data truncation protocol ...... 22 Annex 2. Non-indigenous species (NIS)...... 23

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Tables Table 1. Mean abundance (individuals per 0.1m2), mean biomass (g per 0.1m2) and % occurrence (% of samples in which a taxon was recorded) of the ten numerically dominant macroinfaunal taxa within the Cumbria Coast MCZ. Broad taxonomic groups are in brackets. The taxa with the highest value for a metric are in bold. .... 12

Figures Figure 1. Location of Cumbria Coast MCZ in the context of MPAs and management jurisdictions proximal to the site...... 3 Figure 2. Location of successful ground truth samples collected within the Cumbria Coast MCZ...... 5 Figure 3. Distribution of sediment fractions at particle size analysis sample locations overlying the SAD and intertidal habitat maps (Goodchild, 2013)...... 9 Figure 4. Classification of the sediment samples from the PSA using the proportions of gravel, mud and sand overlain onto the true scale subdivision of the Folk triangle into the simplified classification for UKSeaMap (Long, 2006; Folk, 1954)...... 10 Figure 5. Map of Broadscale Habitat assigned to grab samples from the particle size analysis in the Cumbria Coast MCZ, overlying the SAD predicted habitat map and intertidal habitat map (Irish Seas Conservation Zones, 2011; Goodchild, 2013)...... 11 Figure 6. Mean (with 95% confidence intervals) of a) the total number of species, b) total abundance, and c) total biomass of macroinfauna in subtidal sand (n = 19), subtidal coarse sediment (n = 1), and subtidal mud (n = 3) within the Cumbria Coast MCZ...... 13 Figure 7. Dendrogram of macroinfaunal community composition, based on log (x+1) transformed taxa abundances, within the Cumbria Coast MCZ*...... 14 Figure 8. The spatial distribution of clusters (significantly different at p < 0.05) in macroinfaunal community composition, based on log (x+1) transformed taxa abundances, overlying the SAD and intertidal habitat maps (Goodchild, 2013)...... 15 Figure 9. Mean (with 95% confidence intervals) of a) abundance and b) biomass of juvenile blue mussels (Mytilus edulis) in subtidal sand (n = 19), subtidal coarse sediment (n = 1), and subtidal mud (n = 3) within the Cumbria Coast MCZ...... 17

Cumbria Coast MCZ Subtidal Characterisation Report ii

Executive Summary The Cumbria Coast Marine Conservation Zone (MCZ) is an inshore Marine Protected Area (MPA) included in a network of sites designed to meet conservation objectives under the Marine and Coastal Access Act 2009 and complete a ‘Blue Belt’ of MPAs around the UK coast. These sites will also contribute to an Ecologically Coherent Network of MPAs in the North-East Atlantic agreed under the Oslo Paris (OSPAR) Convention and other international commitments.

Four Broadscale Habitats (BSH) and three habitat Features of Conservation Importance (FOCI) have been designated as features of the inshore Cumbria Coast MCZ. However these habitats have only been recorded in the intertidal or infralittoral areas of the site. This report details the results of a characterisation survey conducted in the subtidal area of the site, with the aim of describing the habitats and biological assemblages present, via grab sampling and acquisition of imagery data.

The subtidal habitats observed within the Cumbria Coast MCZ consisted predominantly of ‘A5.2 Subtidal sand’ and ‘A5.3 Subtidal mud’ habitats. One sample from the BSH ‘A5.1 Subtidal coarse sediment’ was also collected from the area adjacent to St Bees Head. The epibiota throughout the subtidal sand habitat was dominated by individuals belonging to the groups Asteroidea, Liocarcinus, Paguridae, Polychaeta, Sagartiidae; and unidentified faunal turf. None of the video or stills data collected in the areas of potential subtidal mud or coarse sediment were of sufficient quality for analysis.

Macrofaunal samples were collected from both habitats. The macrofaunal community structure within the subtidal sand habitat was found to vary between the different stations. Generally, the community was dominated by the Terebellid worm Lagis koreni, the Spionid worms Magelona johnstoni and Magelona filiformis and the bivalves Nucula nitidosa and Abra Alba. The community structure of the subtidal mud habitat was found to be much more consistent. The macrofaunal community was dominated by the bivalve Kurtiella bidentata, the echinoderm Amphiura filiformis, Lagis koreni and the bivalves Abra alba and Phaxas pellucidus. As only one sample was collected from the subtidal coarse sediment, no community analysis was carried out. The macrofauna from the sample was dominated by the Spionid worm Spiophanes bombyx, the bivalve Nucula nitidosa and the Terebellid worm Magelona filiformis.

No examples of habitat or species FOCI were observed within the subtidal area, although juveniles of the habitat-forming blue mussel, Mytilus edulis, were identified from grab samples. No instances of non-indigenous species were recorded.

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1 Introduction

The Cumbria Coast Marine Conservation Zone (MCZ) is part of a network of sites designed to meet conservation objectives under the Marine and Coastal Access Act (2009). These sites will also contribute to an ecologically coherent network of Marine Protected Areas (MPAs) across the North-east Atlantic, as agreed under the Oslo Paris (OSPAR) Convention and other international commitments to which the UK is signatory.

The MCZ is located on the coast of north-west England, stretching 27 km from Whitehaven in the north to the mouth of the Ravenglass Estuary in the south. It covers an area of approximately 18 km2 and contains the intertidal coastline south of St Bees and the rocky headland, along with subtidal areas adjacent to St Bees Head (Figure 1). St Bees Head supports the most extensive intertidal rocky shore habitats and communities in north-west England. In this area, thriving communities of sponges, sea squirts, tube worms and crustaceans have developed on and under the boulders. Similar communities are also supported at Kokoarrah Rocks, to the south of the MCZ. The honeycomb worm (Sabellaria alveolata) is found intertidally within the MCZ and can form large reef structures of several metres across and up to one metre deep. These biogenic reefs support a wide range of other animals including anemones, snails, shore crabs and seaweeds. Between the rocky habitats, large fine sand beaches are home to polychaetes and small crustaceans, while peat exposures provide habitats into which boring bivalves (e.g., piddocks) and other species can burrow.

The Cumbria Coast MCZ was designated for seven features which had been previously recorded in the intertidal and infralittoral areas of the site. These designated features comprise four Broadscale Habitats (BSH); ‘A1.1 High energy intertidal rock’, ‘A3.2 Moderate energy infralittoral rock’, ‘A2.2 Intertidal sand and muddy sand’, and ‘A2.7 Intertidal biogenic reefs’, in addition to the habitat Features of Conservation Importance (FOCI) ‘Honeycomb Worm (Sabellaria alveolata) reefs’, ‘Peat and Clay Exposures’, and ‘Intertidal Underboulder Communities’.

In 2015, a survey was conducted by the Environment Agency aboard the coastal survey vessel Mersey Guardian, to further investigate and characterise the subtidal areas of the MCZ (Fraser, 2018).

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Figure 1. Location of Cumbria Coast MCZ in the context of MPAs and management jurisdictions proximal to the site.

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1.1 Aims and objectives The aim of this report is to describe the benthic environment of the subtidal area of the Cumbria Coast MCZ, as recorded during the 2015 characterisation survey.

The specific objectives of this report are: 1) Describe the sediment composition at the subtidal stations, and classify samples as Broadscale Habitats (BSH);

2) Compare the sediment BSH classifications and particle size distributions to the predicted habitat layers presented in the Site Assessment Document (SAD) created as part of the final recommendations for MCZs in the Irish Sea by the regional project (ISCZ, 2011);

3) Describe the epifaunal and macrofaunal assemblages at the sampled subtidal stations, according to their BSH classification;

4) Note any observed habitat or species FOCI in the subtidal area; and

5) Note any incidences of Non-Indigenous Species listed under the Marine Strategy Framework Directive (Descriptor 2).

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2 Sample acquisition and processing

2.1 Sampling design A total of 25 subtidal sampling stations were positioned within the MCZ boundary. The locations were selected using a triangular lattice with 500 m spacing, in the absence of a habitat map for the site. A buffer of 200 m was applied between the base of the intertidal zone and the target locations, to account for navigational hazards such as shallow rocky reef features (which could not be surveyed due to poor visibility). Locations of video tows and grab samples collected during this survey are shown in Figure 2.

Figure 2. Location of successful ground truth samples collected within the Cumbria Coast MCZ.

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2.2 Data acquisition and processing

2.2.1 Drop-down imagery A drop-down camera was used to survey epifaunal assemblages and obtain information on habitat type, which was subsequently used to select stations suitable for ground truth sampling using a sediment grab. All imagery data were collected following MESH Recommended Operating Guidelines (Coggan et al., 2007). Video data and still images were collected using a Subsea Technology and Rentals (STR) SeaSpyder drop camera system. Real time navigation data acquisition and manual position fixing was captured via Trimble® HYDROpro™ software. Full details can be found in the survey report (Fraser, 2018). Images of the seabed were captured every 10-15 m over ~150 m. Additional images were taken in heterogeneous areas of BSH and if habitat or species FOCI were observed they were recorded. If a BSH habitat boundary was detected towards the end of a tow, the camera deployment was extended to confirm the change. Both video footage and still images were analysed to utilise the strengths of both techniques; videos being most useful for identifying changes to BSH and stills providing high quality images that are suitable for species identification. Seabed imagery data, used to assess variation in epifaunal assemblages, were interpreted and quality assured by Envision Mapping Ltd.

2.2.2 Grab samples Sediment samples were collected at 25 sampling stations using a 0.1 m2 Hamon Grab (also known as a ‘mini’ Hamon Grab) for particle size distribution and 23 stations for macrofauna analyses (two samples were too small for a standardised fauna sample). Sampling position information was captured using Trimble® HYDROpro™ software.

A 500 ml sub-sample was taken from each grab sample and stored at -20°C prior to determining the particle size distribution. Sediment samples were processed by National Laboratory Service following the recommended methodology of the North East Atlantic Marine Biological Analytical Quality Control (NMBAQC) scheme (Mason, 2011). The less than 1 mm sediment fraction was analysed using laser diffraction and the greater than1 mm fraction was dried, sieved and weighed at 0.5 phi (ϕ) intervals. Sediment distribution data were merged and used to classify samples into sedimentary Broadscale Habitats.

The faunal fraction was sieved over a 1 mm mesh, photographed, then fixed in buffered 4% formaldehyde. At two stations, a valid grab sample (~ 5 litres of sediment) could not be successfully collected. Macroinfauna samples from these stations were therefore discarded, as they would not accurately characterise the targeted community. For all valid samples, animals were extracted and identified to the highest taxonomic resolution possible, enumerated and weighed (blotted wet weight) to the nearest 0.1 mg following the recommendations of the NMBAQC

Cumbria Coast MCZ Subtidal Characterisation Report 6 scheme (Worsfold et al., 2010). Sample processing and identification was carried out by APEM Ltd.

2.3 Data preparation and analysis

2.3.1 Sediment sample analysis Sediment particle size distribution data (half phi classes) were grouped into the percentage contribution of gravel, sand and mud derived from the classification proposed by Folk (1954). In addition, each sample was assigned to one of four sedimentary Broadscale Habitats based on the simplified classification for UKSeaMap (Long, 2006; Folk, 1954):

• A5.1 Subtidal coarse sediment

• A5.2 Subtidal sand

• A5.3 Subtidal mud

• A5.4 Subtidal mixed sediments

Sediment samples for the subtidal areas were compared to the predicted habitats from the Site Assessment Document (SAD) created as part of the final recommendations for Marine Conservation Zones in the Irish Sea by the regional project (ISCZ, 2011).

2.3.2 Epifaunal data Epibiota communities were assessed using only data obtained from the still images. Poor visibility, due to suspended sediment, made video data unsuitable for species identification. The same issue also meant that habitat type and epifaunal community data could only be derived from still images acquired at 8 of the 25 sampling stations (Figure 2). Any highly mobile taxa (e.g. fish) were removed from the dataset, as they are not reliably surveyed using seabed imagery.

As seabed imagery were only available for eight sampling stations, all of which were situated on the same habitat type and supported very few taxa, analysis of epifauna consisted of a simple description of the observed taxa and the relative abundances at which they occurred.

2.3.3 Macroinfaunal data Macroinfaunal data were available for 23 of the 25 survey stations. The identified taxa were checked for the application of consistent and up-to-date nomenclature using WoRMS1. Any recorded taxa that cannot be considered as macroinfauna were removed from the dataset, as were any fragments of individuals. Abundances were combined when both adults and juveniles of the same taxon were recorded.

1 http://www.marinespecies.org

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Cases where a taxon comprised only juveniles, or a mixture of adults and juveniles, were noted in the truncated dataset. Colonial taxa, whose abundances could not be measured, were assigned an abundance of ‘1’ for each sample in which they were recorded. A full description and rationale for the truncation process is provided in Annex 1.

The total number of species, total abundance, and total biomass at each station (based on a 0.1 m2 grab sample) were used to indicate biodiversity and faunal density. No formal tests of differences in these metrics among BSHs were carried out, as the number of samples per habitat varied substantially (19 for ‘A5.2 Subtidal sand’, three for ‘A5.3 Subtidal mud’, and one for ‘A5.1 Subtidal coarse sediment’), thus precluding reliable tests of statistical significance. However, 95% confidence intervals around the means were used to help interpret variation in these indices with respect to BSH where possible. If any habitat FOCI species were recorded in the grab samples, their abundances and biomasses were plotted in relation to BSH in the same way as described for other univariate indices.

Macroinfaunal taxa abundance data were then imported into Primer V6 (Clarke and Gorley, 2006) for analysis of community composition. Cluster analysis with SIMPROF was used to identify stations with significantly different communities (p < 0.05), based on the Bray-Curtis Similarity Index. Data were transformed by log (x+1) to reduce the influence of dominant taxa and allow variation in the densities of rarer taxa to be detected. The results of cluster analysis were compared against the BSH types (determined by sediment particle size analysis, see section 2.3.1) to assess whether distinct assemblages tended to be associated with the different BSHs. SIMPER was then used to identify taxa that contributed most to variation in community composition among clusters.

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3 Results 3.1 Particle Size Distribution

Across the site, proportions of gravel ranged from 0.06% to 5.05% with an average of 0.66% gravel across all samples. Variations in the proportions of sand and mud were slightly larger, with sand ranging from 70.30% to 99.91% and mud ranging from 0.00% to 28.56%. The samples with the highest proportions of mud were found to occur in the deeper areas furthest from the coast (Figure 3) while the inshore samples around the headland were dominated by very high (>98%) proportions of sand. Gravel was observed only in the northern half of the survey area.

It was not possible to generate a habitat map for the subtidal area based on the data acquired, however, the proportions of gravel, sand and mud are displayed alongside a detailed habitat map of the intertidal area produced as part of the verification survey of the intertidal habitats (Figure 3).

Figure 3. Distribution of sediment fractions at particle size analysis sample locations overlying the SAD and intertidal habitat maps (Goodchild, 2013).

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3.2 Broadscale Habitats

Based on the simplified sedimentary classification scheme for UKSeaMap (Long, 2006; Folk, 1954) (Figure 4), 21 of the samples were classified as the BSH ‘A5.2 Subtidal sand’, three samples as ‘A5.3 Subtidal mud’ and one as ‘A5.1 Subtidal coarse sediment’. The samples classified as ‘A5.2 Subtidal sand’ were located across the site, to both the north and south of St Bees Head. The three stations classified as ‘A5.3 Subtidal mud’ were in the area furthest offshore, to the west of St Bees Head, while the one station classified as ‘A5.1 Subtidal coarse sediment’ was in the centre of the site, to the north of the headland.

Figure 4. Classification of the sediment samples from the PSA using the proportions of gravel, mud and sand overlain onto the true scale subdivision of the Folk triangle into the simplified classification for UKSeaMap (Long, 2006; Folk, 1954). Accordance between the PSA samples and the SAD habitat map was moderate with 48% of the samples agreeing with the underlying predicted habitat map (Figure 5). Of the 21 samples classified as ‘A5.2 Subtidal sand’, eight occurred in the predicted sand habitat, with the remaining samples occurring in the area mapped as ‘A5.3 Subtidal mud’. The one sample classified as ‘A5.1 Subtidal coarse sediment’ was found to occur in the predicted ‘A5.3 Subtidal mud’ habitat. All three samples classified as ‘A5.3 Subtidal mud’ were found to occur in the predicted ‘A5.3 Subtidal mud’ habitat.

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Figure 5. Map of Broadscale Habitat assigned to grab samples from the particle size analysis in the Cumbria Coast MCZ, overlying the SAD predicted habitat map and intertidal habitat map (Irish Seas Conservation Zones, 2011; Goodchild, 2013).

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3.3 Biological community analysis

All images, which were determined to be suitable for analysis, were classified as the BSH ‘A5.2 Subtidal sand’. Commonly identified species from the still images included Asteroidea, Liocarcinus, Paguridae, Polychaeta, Sagartiidae, and unidentified faunal turf. Further analysis of the epibiota community structure is described in Section 3.3.1.

For macroinfauna collected from the grab samples, a total of 5344 individuals from 121 taxa were recorded at 23 survey stations (one 0.1 m2 sample collected per station). The ten most abundant taxa are shown in Table 1, along with their mean abundance, mean biomass, and percentage occurrence (i.e. percentage of samples in which they were present). The polychaete Lagis koreni was the numerically dominant species, occurring at a mean density of 69 individuals per sample and making up 30% of total abundance. Biomass was dominated by the bivalve Abra alba, which occurred at an average weight of 0.82 g per sample and made up 22% of total biomass. The polychaete Spiophanes bombyx was the most widely- distributed macroinfaunal species, occurring at 21 out of 23 stations (91%). A description of macroinfaunal communities in each BSH is provided in the following sections.

Table 1. Mean abundance (individuals per 0.1m2), mean biomass (g per 0.1m2) and % occurrence (% of samples in which a taxon was recorded) of the ten numerically dominant macroinfaunal taxa within the Cumbria Coast MCZ. Broad taxonomic groups are in brackets. The taxa with the highest value for a metric are in bold.

Taxon Mean abundance Mean biomass % Occurrence

Lagis koreni (Polychaeta) 69.2 0.59 57 Kurtiella bidentata (Bivalvia) 32.0 0.05 48 Magelona johnstoni (Polychaeta) 15.6 0.03 83 Amphiura filiformis (Echinodermata) 15.3 0.58 26 Nucula nitidosa (Bivalvia) 12.6 0.15 65 Abra alba (Bivalvia) 11.8 0.82 65 Magelona filiformis (Polychaeta) 9.3 0.01 70 Pharus legumen* (Bivalvia) 8.4 0.15 57 Spiophanes bombyx (Polychaeta) 6.9 0.01 91 Phaxas pellucidus (Bivalvia) 6.5 0.03 57 *Individuals consisted of both adults and juveniles.

3.3.1 A5.2 Subtidal sand A total of seven epifaunal taxa were recorded in 76 still images collected from ‘A5.2 Subtidal sand’ at eight survey stations, including; Asteroidea, Astropecten irregularis, Liocarcinus sp., Paguridae, Polychaeta, Sagartiidae and unidentified faunal turf. It is noted, however, that Astropecten irregularis lies within the broader taxonomic group

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Asteroidea. The single individual recorded as Asteroidea was only partly in view within the still image, thus preventing identification beyond the class-level. It is therefore possible that the individual recorded as Asteroidea also belongs to the species Astropecten irregularis. Nineteen epifaunal individuals were recorded in total. The most abundant taxon was Polychaeta, which was observed six times. Individuals of all other epifaunal taxa were recorded between one and four times.

On average, macroinfauna samples collected from subtidal sand contained 189 individuals across 20 taxa, weighing a total of 2.9 g (Figure 6). Lagis koreni was the most abundant macroinfaunal species (71 individuals per sample), followed by the polychaete Magelona johnstoni (19 individuals), two bivalves, Nucula nitidosa (12 individuals) and Abra Alba (11 individuals), and another polychaete Magelona filiformis (11 individuals). Biomass was dominated by Abra alba (0.72 g), followed by Lagis koreni (0.64 g), the gastropod Euspira catena (0.37 g), and the bivalves Chamelea striatula (0.34 g) and Nucula nitidosa (0.16 g). The top five species in order of % occurrence were Spiophanes bombyx (100%), Magelona johnstoni (95%), the polychaete Glycera tridactyla (84%), Magelona filiformis (74%) and Abra alba (63%).

Figure 6. Mean (with 95% confidence intervals) of a) the total number of species, b) total abundance, and c) total biomass of macroinfauna in subtidal sand (n = 19), subtidal coarse sediment (n = 1), and subtidal mud (n = 3) within the Cumbria Coast MCZ. Macroinfaunal community composition in subtidal sand was variable, with an average sample similarity of 37%. SIMPROF divided subtidal sand communities into three discrete clusters, which were significantly different at p < 0.05 (labelled ‘a’, ‘b’, and ‘c’ in Figure 7). These clusters were spatially segregated, with cluster ‘a’ running along the coast in shallow waters both north and south of St Bees Head, cluster ‘b’ running southward from St Bees Head along the south-western boundary of the MCZ, and cluster ‘c’ running northward from St Bees Head along the north- western boundary of the MCZ (Figure 8). Dissimilarity among clusters was due to various taxa having relatively low abundances in cluster ‘a’, high abundances in cluster ‘b’, and intermediate abundances in cluster ‘c’. The crab Portumnus latipes

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(juveniles) was the only major contributor to community dissimilarity that occurred in relatively high abundances in cluster ‘a’.

Figure 7. Dendrogram of macroinfaunal community composition, based on log (x+1) transformed taxa abundances, within the Cumbria Coast MCZ*.

* Distinct clusters (significantly different at p < 0.05) are separated by black branches, labelled: ‘a’, ‘b’, ‘c’ and ‘d’. Survey stations within clusters (not significantly different from each other) are separated by red branches. Broadscale Habitat type is marked: = Subtidal sand, = Subtidal coarse sediment, = Subtidal mud.

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Figure 8. The spatial distribution of clusters (significantly different at p < 0.05) in macroinfaunal community composition, based on log (x+1) transformed taxa abundances, overlying the SAD and intertidal habitat maps (Goodchild, 2013).

3.3.2 A5.1 Subtidal coarse sediment No imagery data were available to characterise the epibiotic assemblages within the BSH ‘A5.1 Subtidal coarse sediment’. Although the sediment was classified as such in the particle size analysis, the sample had a very similar sedimentary composition to the samples classified as ‘A5.2 Subtidal sand’. A decrease of just 0.06% gravel would reclassify the sample as ‘A5.2 Subtidal sand’.

Twenty-one macroinfaunal taxa, 51 individuals, with a total biomass of 0.16 g were recorded in the single grab sample taken from ‘A5.1 Subtidal coarse sediment’

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(Figure 6). Spiophanes bombyx was the most abundant taxon (15 individuals), followed by Nucula nitidosa (seven individuals), Magelona filiformis (five individuals), Magelona johnstoni (four individuals), and the polychaete Chaetozone christiei (three individuals). The taxon with the highest biomass was Nucula nitidosa (0.04 g), followed by Magelona johnstoni (0.03 g), Spiophanes bombyx (0.02 g), Chamelea striatula (0.02 g), and Chaetozone christiei (0.01 g).

Macroinfaunal community composition in the subtidal coarse sediment sample was clustered within a subset of subtidal sand communities (cluster ‘c’; Figure 7). Therefore, this BSH was not associated with a distinct benthic assemblage at the site.

3.3.3 A5.3 Subtidal mud No imagery data were available to characterise the epifaunal assemblages within the BSH ‘A5.3 Subtidal mud’.

Macroinfaunal assemblages in subtidal mud contained an average of 35 taxa, 570 individuals, and 10 g of biomass per sample (Figure 6). The bivalve Kurtiella bidentata was the most abundant species (227 individuals per sample), followed by the echinoderm Amphiura filiformis (117 individuals), Lagis koreni (80 individuals), Abra alba (21 individuals) and another bivalve, Phaxas pellucidus (18 individuals). In terms of biomass, the dominant species was Amphiura filiformis (4.47 g), followed by Abra alba (1.69 g), the crab Goneplax rhomboids (0.76 g), the bivalve Pharus legumen (0.62 g), and the polychaete Aphrodite aculeata (0.54 g). Fourteen macroinfaunal taxa occurred at all three survey stations where the habitat type was subtidal mud, including four of the numerically dominant taxa: Kurtiella bidentata, Amphiura filiformis, Lagis koreni and Phaxas pellucidus.

Macroinfaunal communities within subtidal mud were relatively stable, with an average of 63% similarity among samples. Subtidal mud communities formed a discrete cluster that was significantly different (p < 0.05) to communities found in the other BSH (cluster ‘d’; Figure 7). This difference was largely due to higher taxon abundances in mud, with Kurtiella bidentata, Amphiura filiformis, Lagis koreni, the polychaete Pholoe balthica, and the gastropod Hyala vitrea the top contributors in this regard. Magelona johnstoni, Magelona filiformis, and Spiophanes bombyx were among the major contributors to community dissimilarity between mud and other habitat types that occurred in relatively low abundances in mud. The cluster consisting of all three subtidal mud stations was situated in relatively deep water to the west of St Bees Head, close to the MCZ boundary (cluster ‘d’; Figure 8).

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3.4 Habitat Features of Conservation Importance

3.4.1 Blue Mussel (Mytilus edulis) Beds The habitat FOCI ‘Blue Mussel (Mytilus edulis) Beds’ was included in the SAD for Cumbria Coast MCZ, but to date has not been designated as a feature of the site. No M. edulis beds were observed from video footage or still images collected during the survey. However, juvenile M. edulis were recorded in the grab samples. A total of 77 individuals were recorded, all of which were from samples classified as ‘A5.2 Subtidal sand’ and ‘A5.3 Subtidal mud’. Abundance and biomass of M. edulis juveniles was relatively high in mud, but also highly variable (Figure 9).

Figure 9. Mean (with 95% confidence intervals) of a) abundance and b) biomass of juvenile blue mussels (Mytilus edulis) in subtidal sand (n = 19), subtidal coarse sediment (n = 1), and subtidal mud (n = 3) within the Cumbria Coast MCZ. 3.4.2 Other Habitat FOCI None of the designated habitat FOCI for Cumbria Coast MCZ were identified during the survey due to sampling taking place in the subtidal areas (with a 200 m buffer around rocky structures), away from where the habitat FOCI were previously recorded.

3.4.3 Species Features of Conservation Importance No species FOCI were observed from imagery or grab sample data.

3.5 Non-indigenous species

All taxa identified in grab and video samples collected in 2015 were cross-referenced against a list of 49 non-indigenous target species which have been selected for assessment of Good Environmental Status in GB waters under MSFD Descriptor 2 (Stebbing et al., 2014; Annex 2).

There were no non-indigenous taxa observed in the still images or identified from the macrofaunal sediment samples.

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4 Discussion

The primary objectives of this subtidal characterisation report were to characterise and classify the Broadscale Habitats within in the Cumbria Coast MCZ, in the context of the predictive SAD map (ISCZ, 2011), and to describe the epifaunal and macrofaunal assemblages at the sampled stations.

The PSD data were in partial agreement with the predictive map created for the SAD, however discrepancies between the sediment sample classifications and the predictive habitat map did occur for a number of stations, particularly in the area to the south of St Bees Head ,where sediment samples were classified as ‘A5.2 Subtidal sand’ but were overlying an area predicted to comprise ‘A5.3 Subtidal mud’.

Classification of macroinfaunal communities into one of the four possible sedimentary BSH is not necessarily ecologically relevant. Biological communities do not align with the same physical thresholds used in the classification of sedimentary BSHs; although sediments across the site were classified between three BSH, the differences in the proportions of gravel, sand and mud between the stations were relatively small, requiring only a small variation for a sample to change between BSH categories. Furthermore, given the high-energy environment occurring around St Bees Head, the sediment boundaries between the different BSHs are likely to be both highly mobile and indistinct.

The epifauna and macroinfauna recorded are typical of assemblages commonly observed in the sedimentary habitats with which they were associated. High turbidity meant that epifaunal communities could only be reliably identified using the drop camera at eight stations, all located on the BSH ‘A5.2 Subtidal sand’ to the north of St Bees Head (Figure 2). In the absence of such data for the majority of stations (17), as well as due to poor visibility at many of the stations from which data were obtainable, the survey reported on here provides a limited characterisation of epifaunal communities within the Cumbria Coast MCZ. As no data were available for ‘A5.1 Subtidal coarse sediment’ and ‘A5.3 Subtidal mud’, the epifaunal communities associated with these BSHs remain uncharacterised. Conversely, macroinfauna communities were successfully sampled using benthic grabs for 23 out of 25 sites. The two remaining un-sampled stations were both located on the ‘A5.2 Subtidal sand’ BSH, within which 19 stations were successfully sampled, thereby allowing an adequate characterisation of the macroinfaunal communities associated with this BSH.

Macroinfaunal community composition within the surveyed area fell into four discrete clusters. Three of these clusters occurred among stations within the BSH ‘A5.2 Subtidal sand’ and were spatially segregated with respect to: 1) proximity to the coast (i.e., cluster ‘a’ occurred close to the coast whereas clusters ‘b’ and ‘c’ were further offshore) and 2) latitude (i.e., cluster ‘b’ occurred to the south of St Bees Head whereas cluster ‘c’ occurred to the north) (Figure 8). The one station situated

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on the BSH ‘A5.1 Subtidal coarse sediment’ also fell within one of these clusters (cluster ‘c’), which is not unexpected given that the PSA placed it on the boundary between coarse sediment and sand (Figure 4). Stations that formed cluster ‘d’ were aggregated at the western extent of the MCZ (Figure 8), where the BSH was identified as ‘A5.3 Subtidal mud’ (Figure 5). It therefore appears that multiple environmental factors, including habitat type, may underlie the observed spatial heterogeneity in the benthos within the Cumbria Coast MCZ. Indeed, the more diverse taxa, along with higher total abundance and biomass, in mud may reflect a greater food supply in the form of organic detritus (Pearson and Rosenberg 1978; Weigel et al., 2015). Variation in water depth and hydrodynamics within the MCZ could also play a key role in shaping spatial patterns in benthic communities (Rosenberg, 1995). This spatial heterogeneity, both within and among BSHs, is an important consideration for any future surveys within the subtidal area of the site.

To assess variation in community composition based on taxa abundances, colonial taxa were given an abundance of ‘1’. This will inevitably have underrepresented their population sizes compared to non-colonial taxa and therefore introduced a degree of inaccuracy to the characterisation of the benthos within the MCZ. Unfortunately, there is no simple approach to address this issue without practical methods by which their abundances can be estimated. However, one possibility is to carry out analyses of variation in community composition using taxa biomass data. While biomass also does not reflect population size per se, it is nonetheless a measure of density that allows representative comparisons to be made across colonial and non-colonial animals. Moreover, biomass is a major determinant of the degree to which taxa drive their associated ecological functions (Grime, 1998; Garnier et al., 2004).

None of the habitat FOCI for which the Cumbria Coast MCZ is designated were recorded during the 2015 survey. ‘Honeycomb Worm (Sabellaria alveolata) reefs’, and ‘Intertidal Underboulder Communities’ both occur in the intertidal zone. Of the three designated habitat FOCI, only ‘Peat and clay exposures’ could have occurred in the surveyed subtidal area. This habitat FOCI was not observed on this occasion, despite having been observed further south in the subtidal zone, and within the intertidal zone (SAD map; ISCZ, 2011). No undesignated species or habitat FOCI were observed.

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5 References Clarke, K.R. and Gorley, R.N. (2006). PRIMER v6: User Manual/Tutorial. PRIMER- E, Plymouth. 192 pp. Coggan, R., Mitchell, A., White, J. and Golding, N. (2007). Recommended operating guidelines (ROG) for underwater video and photographic imaging techniques http://webarchive.nationalarchives.gov.uk/20101014084849/http://www.searchmesh. net/PDF/GMHM3_Video_ROG.pdf [Accessed 17/08/2018] Folk, R.L. (1954). The distinction between grain size and mineral composition in sedimentary rock nomenclature. Journal of Geology 62, 344-359. Fraser, M. (2018). Cumbria Coast MCZ 2015 Survey Report. Environment Agency. In preparation. Garnier, E., Cortez, J., Billès, G., Navas, M-L., Roumet, C., Debussche, M., Laurent, G., Blanchard, A., Aubry, D., Bellmann, A., Neill, C. and Toussaint, J-P. (2004). Plant functional markers capture ecosystem properties during secondary succession. Ecology 85: 2630–2637. Grime, J.P. (1998). Benefits of plant diversity to ecosystems: immediate, filter and founder effects. Journal of Ecology 86: 902–910. Goodchild, R. (2013). Verification survey of intertidal habitats within the Cumbria Coast MCZ. Natural England. Report Number NECCMCZ0613. 154 pp Irish Sea Conservation Zones (ISCZ) (2011). Final recommendations for Marine Conservation Zones in the Irish Sea http://www.irishseaconservation.org.uk [Accessed 17/08/2018] Long, D. (2006). BGS detailed explanation of seabed sediment modified folk classification.

Mason, C. (2011). NMBAQC’s Best Practice Guidance Particle Size Analysis (PSA) for Supporting Biological Analysis. National Marine Biological AQC Coordinating Committee. 77 pp. First published 2011, updated January 2016. http://www.nmbaqcs.org/media/1255/psa-guidance_update18012016.pdf [Accessed 23/08/2018].

Pearson, T.H. and Rosenberg, R. (1978). Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology – An Annual Review 16: 229–311. Rosenberg, R. (1995). Benthic marine fauna structured by hydrodynamic processes and food availability. Netherlands Journal of Sea Research 34: 303–317. Stebbing, P., Murray, J., Whomersley, P. and Tidbury, H. (2014). Monitoring and surveillance for non-indigenous species in UK marine waters. Defra Report. 57 pp.

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Weigel, B., Anderson, H.C., Meier, H.E.M., Blenckner T., Snickars, M. and Bonsdorff, E. (2015). Long-term progression and drivers of coastal zoobenthos in a changing system. Marine Ecology Progress Series 528: 141–159. Worsfold, T.M., Hall., D.J. and O’Reilly, M. (2010). Guidelines for processing marine macrobenthic invertebrate samples: a processing requirements protocol version 1 (June 2010). Unicomarine Report NMBAQCMbPRP to the NMBAQC Committee. 33 pp. http://www.nmbaqcs.org/media/1175/nmbaqc-inv-prp-v10-june2010.pdf [Accessed 17/08/2018].

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Annex 1. Macroinfauna data truncation protocol A number of decisions applied during the data truncation process are described here, with the intention that by following such decisions, a greater degree of consistency in truncation exercises across different studies may be achieved. Raw taxon-by-sample matrices can often contain entries that include the same taxa recorded differently, erroneously or differentiated according to unorthodox, subjective criteria, for example: Each row should represent a legitimate taxon to be used in analytical software packages as a unit for the calculation of diversity indices and of similarity amongst groups of samples. An artificially inflated taxon list (i.e., one that has not had spurious entries removed) risks distorting the interpretation of pattern contained within the sampled assemblage. The truncation exercise aims to identify and neutralise such entries to reduce the risk of them supporting an artificial pattern in the assemblage. It is often the case that to overcome uncertainty and to avoid the introduction of unsupported certainty, some taxa have to be merged to a level in the taxonomic hierarchy that is higher than the level at which they were identified. In such situations, a compromise must be reached between the level of information lost by discarding recorded detail on a taxon’s identity, and the potential for error in analyses, results and interpretation if that detail is retained. Where there are records of one named species together with records of members of the same genus but the latter not identified to species level, the entries are merged and the resulting entry retains only the name of the genus (i.e., species level information is forfeited). In this way, the entries identified only to genus are not assigned to a level that is unsupported by the evidence, and the resulting single entry is representative of both original entries, albeit with a little less information, but a loss that will not affect the pattern in the assemblage as a whole. Additionally, taxa are often assigned as ‘juveniles’ during the identification stage with little evidence for their actual reproductive natural history (with the exception of some well-studied molluscs and commercial species). Many truncation methods involve the removal of all ‘juveniles’. However, a decision must be made on how to avoid the issues discussed above while retaining valuable information within the multivariate data set. The term ‘juvenile’ is often used to refer to individuals which do not exhibit the morphological features to resolve them to species level. In this case, these records were removed from the analysis rather than lowering the taxonomic resolution of other species level identifications. When a species level identification was labelled ‘juvenile’ the record was combined with the associated species level identification, when present or the ‘juvenile’ label removed.

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Annex 2. Non-indigenous species (NIS). Taxa listed as non-indigenous species (present and horizon) which have been selected for assessment of Good Environmental Status in GB waters under MSFD Descriptor 2 (Stebbing et al., 2014).

Species name List Species name List Acartia (Acanthacartia) tonsa Present Alexandrium catenella Horizon Amphibalanus amphitrite Present Amphibalanus reticulatus Horizon

Asterocarpa humilis Present Asterias amurensis Horizon Bonnemaisonia hamifera Present Caulerpa racemosa Horizon

Caprella mutica Present Caulerpa taxifolia Horizon

Crassostrea angulata Present Celtodoryx ciocalyptoides Horizon

Crassostrea gigas Present Chama sp. Horizon

Crepidula fornicata Present Dendostrea frons Horizon

Diadumene lineata Present Gracilaria vermiculophylla Horizon

Didemnum vexillum Present Hemigrapsus penicillatus Horizon

Dyspanopeus sayi Present Hemigrapsus sanguineus Horizon

Ensis directus Present Hemigrapsus takanoi Horizon

Eriocheir sinensis Present Megabalanus coccopoma Horizon

Ficopomatus enigmaticus Present Megabalanus zebra Horizon

Grateloupia doryphora Present Mizuhopecten yessoensis Horizon

Grateloupia turuturu Present Mnemiopsis leidyi Horizon

Hesperibalanus fallax Present Ocenebra inornata Horizon

Heterosigma akashiwo Present Paralithodes camtschaticus Horizon

Homarus americanus Present Polysiphonia subtilissima Horizon

Rapana venosa Present Pseudochattonella verruculosa Horizon

Sargassum muticum Present Rhopilema nomadica Horizon

Schizoporella japonica Present Telmatogeton japonicus Horizon

Spartina townsendii var. anglica Present

Styela clava Present

Undaria pinnatifida Present

Urosalpinx cinerea Present

Watersipora subatra Present

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