Eddystone Reef Camera Survey Summary Report 2014-2017

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Stephen K. Pikesley Jean-Luc Solandt Colin Trundle Matthew J. Witt

December 2017

All data remain copyright of the project partners. Maps or data within this report may not be used or referenced without the explicit written consent of the data owners.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Executive summary

The Eddystone Reef is part of the Start Point to Plymouth Sound and Eddystone Special Area of Conservation (SAC). In January 2014 management measures were introduced to prohibit bottom-towed fisheries from using key areas within the SAC, thereby creating a mosaic of protected areas that may provide protection to vulnerable reef-associated species. Ideally, newly established protected areas should be monitored over time to observe change in biological communities attributable to adopted management strategies.

This project is a collaborative partnership between the Marine Conservation Society (MCS), Cornwall Inshore Fisheries and Conservation Authority (CIFCA) and the University of Exeter (UoE); funded by the Pig Shed Trust (2014-2016, and 2020) and Princess Yachts (2017-2019). The principal aim of this project is to monitor and record changes to benthic communities in these newly protected areas.

This report details survey activities for the first four years of the project, 2014-2017. Drop-down camera surveys in 2017 produced 235 images of the seabed that allowed identification of 664 benthic organisms (n = 27 species identified to highest generic species classification). Surveys in 2016 produced 406 images that allowed identification of 1387 benthic organisms (n = 26 species: highest generic species classification). Surveys in 2015 produced 428 images that allowed identification of 1542 benthic organisms (n = 27 species) and surveys conducted in 2014 resulted in 214 images which yielded 372 benthic organisms (n = 22 species).

Surveys in 2015, 2016 and 2017 have built on the library of seabed images gathered for the Eddystone Reef complex based on primary surveys in 2014. Continued monitoring throughout 2018-2019 will likely improve the robustness of any findings regarding seabed communities in the region and any changes thereof, as response to management regimes in place at the site.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Contents

Executive summary 1

Introduction 3

Aims & Objectives 5

Method 6

Results 9

Discussion 29

Appendices Appendix 1: Species identification confidence 31 Appendix 2: Substratum and image quality 32 Appendix 3: Data table for Figs. 12 and 13 33

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Introduction

On the 1st of January 2014 Cornwall Inshore Fisheries Conservation Authority (CIFCA) Closed Areas European Marine Sites (EMS) Byelaw came into force, this prohibited the use of bottom-towed fishing gear within EMS throughout the district. One such area that benefited from protection was the Eddystone Reef complex. Eddystone Reef is situated approximately nine nautical miles off the southern coast of Cornwall (South West UK) and comprises part of the Start Point to Plymouth Sound and Eddystone Special Area of Conservation (SAC). The Eddystone Reef was subsequently zoned to protect key site features (Figure 1). The local seabed habitats are too deep (at over 45 m) to safely deploy SCUBA divers to monitor the effects of the fisheries closure, hence remote survey techniques have been employed to gather data. The benthic habitats of the Eddystone Reef provide an important opportunity to use remote seabed video and drop-down camera surveys to monitor and to quantify the response of these benthic ecosystems following the cessation of bottom-towed fishing effort.

A multi-partner collaborative consortium, led by the Marine Conservation Society (MCS), with CIFCA and the University of Exeter (UoE), have undertaken to survey these newly protected habitats to monitor for long- term changes to the seabed as it is released from towed gear fishing pressure. As well as gaining insight into the recovery of these habitats it is anticipated this project will foster a collaborative working relationship between NGOs, regulators and others (such as Universities, and Statutory Nature Conservation Bodies) that will provide a progressive, more cohesive approach to UK marine conservation.

In this report, we detail data collection and seabed image metadata analysis for the first four years of the project at the Eddystone Reef complex.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Figure 1. Eddystone Special Area of Conservation (SAC) study area. (a) Eddystone SAC (grey polygon) in relation to Cornwall Inshore Fisheries and Conservation Authority (CIFCA) district boundary (broken line polygon) in south eastern Cornwall. Part (a) is located according to the inset (b). (c) Eddystone SAC detailing areas closed to bottom-towed gear (red hatched polygon) and areas with no gear restrictions (green hatched polygon). In all parts 50 m isobath is drawn and labelled; survey boxes are drawn as blue polygons and labelled in part (c). All map parts are drawn to differing spatial scales. Maps drawn to Projected Coordinate System: British National Grid Transverse Mercator.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Aims & Objectives

Aims of the project

1. To identify any changes to the seabed habitats of Eddystone Reef, subject to new management restrictions of bottom-towed fishing gears. 2. To identify patterns in the diversity and abundance of sessile and mobile species and commercial species that are recorded during seabed photographic surveys. 3. To collaboratively report the results of the surveys to the local interest groups/stakeholders to illustrate the effects of management measures on commercial and biodiversity interests in Cornish waters.

Objectives of the project

1. Analyse high-resolution photographic imagery of habitats, and the change in the extent and type of habitat over time that are subject to management measures. 2. To highlight how management of bottom-towed fishing gears might result in changes to seabed species and habitats. 3. To foster greater co-ordinated working between regulators, conservation advisors and NGOs, in light of new progressive spatial management of heavy impact mobile fishing gears.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Method

Survey design

Surveys of the seabed were undertaken within three survey boxes (0.44 km2 each) using drop-down camera survey techniques. Prior to 2014 the seafloor area circumscribed by box 1 (treatment area) was open to fisheries deploying bottom towed gear, primarily scallop dredges. Following the introduction of new management measures (1st January 2014) this box, and adjacent reef habitat, were closed to bottom towed fisheries. The box is situated within the Eddystone SAC and encompasses known rocky reef and circalittoral mixed sediment habitats with seabed depths of approx. 50 m. Box 2 lies within close proximity to the Eddystone SAC (approx 0.25 km north) and is located within a region that has experienced no change in management regime; it lies approx 1.5 km west-northwest of box 1, and is considered the near reference area. Box 3 is situated approx 11.5 km west- northwest of box 1. Box 3 is considered a distant reference area in the experimental design; similarily it has experienced no change in management measures. Both boxes 2 and 3 encompass similarly comprised rock and circalitoral mixed sediment habitats with seabed depths of approx. 50 m. For all boxes, intial surveys where underatken within 6/7 months during the first year that new fisheries management measures were introduced. This experimental approach allows for a pseudo ‘Beyond BACI’ (Before/After and Control/Impact) approach to be adopted by monitoring habitats within close proximity, with and without management, whilst monitoring a similarily comprised habitat, without management, at a distance, thereby removed from localised influences.

Data collection

Drop-down camera surveys were conducted in June/July 2014, July 2015, July/October 2016 and July/August 2017 (see Tables 1,2,3 and 4 for survey metadata). Photographic images were collected in accordance with the Cornwall Inshore Fisheries and Conservation Authority (CIFCA) 2014 Field Report V0.3 (2014), 2015 Eddystone Field Report July 2015 V0.2 (2015), Eddystone Field Report 20160718 V0.3 (2016), Eddystone Field Report 20161010 V0.2 (2016), Eddystone Field Report 20170704 (2017) and Eddystone Field Report 20170825 (2017) (see seperate reports). Survey transect methodology in 2015, 2016 and 2017 mirrored that established during 2014. Where possible, the spatial footprint of annual survey transects took advantage of the maximum spatial extent of the relevant survey box

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

(Figure 2,3 and 4). In 2014, images of very poor quality (image excessively blurred due to camera movement or seabed obscured by sediment suspension) were removed from the stills catalogue before these data were transfered to the University of Exeter (UoE) for analysis. In 2015, 2016 and 2017 all images were transferred to UoE for analysis irrespective of image quality.

Camera stills analysis

Analysis of the still images gathered in 2014, 2015, 2016 and 2017 was undertaken as follows. Images without spatial reference (no longitude or latitude recorded), or where no movement of the camera frame had been recorded (no change in location between successive images), or where the camera frame was not positioned on the seabed when the image was captured, were first removed from the analysis.

Each image (resolution: 5184 x 3456 pixels) was then examined at full frame using a 1920 x 1080 pixel monitor resolution and the following information recorded. The substratum was described and classified using European Union Nature Information System (EUNIS) habitat classifications (e.g. circalittoral mixed sediments: 5.44). The substratum was further categorised based on the visible dominant (> 50%) bottom type using a four part classification: fine (F) , medium (M), coarse (C) and rock/reef feature (R/R). The clarity of each image (image quality) was categorised using a three part classification system: good, moderate and poor based on the sharpness of the image (focus and lack of camera movement) and amount of particle suspension present. To approximate the field of view captured by the image the on-screen distance between visble laser marks were measured. These distances also enabled confirmation of contact of the camera frame with the seabed. The number of laser marks present in each image was also counted.

Images were then viewed at full width and panned from top to bottom and the presence of all conspicuous benthic organisms recorded. These were then identified to their highest taxonomic level (e.g. Eunicella verucosa), if this was not possible individuals were recorded by highest generic species description (e.g. bryozoa (encrusting), sea squirt, nudibranch, sponge (encrusting/cushion), sponge (erect)). If required the image was zoomed further to aid identification. Confidence in species identification was recorded on the following scale: low confidence (C1), moderate confidence (C2) and high confidence (C3). This scale represents a subjective assessment based on multiple compounding factors including, but not limited to:

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017 amount of organism visible, position of organism in relation to centre of image (vignetting of image), angle of incidence and intensity of lighting, seabed siltation present, composition of underlying substratum and general image quality (blur, sediment suspension in water column). See Appendix 1 for examples of species id confidence. The total number of each species within each image was recorded. Where species were encrusting or turf forming (e.g. bryozoa/hydroid turf, encrusting bryozoa) a gridded overlay was placed on the monitor screen and a visual assessment of the percentage coverage of these species was made with the image viewed at full frame. As camera look angle was near perpendicular to the seabed no trapezoid correction was made. A relative abundance SACFOR score (S: super abundant, A: abundant, C: common, F: frequent, O: occasional and R: rare) adapted from the Marine Nature Conservation Review (MNCR) SACFOR abundance scales (http://jncc.defra.gov.uk/) was then assigned to each species recorded.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Results

Building on the Eddystone Reef camera survey reports for 2014, 2015 and 2016 this report details data collection and seabed image metadata analysis for the first four years (2014 to 2017) of the project at the Eddystone Reef complex.

Survey strategy and image capture

The field of view captured by the images approximates to 640 mm (width) by 400 mm (height); approx. 0.25 m2. See Table 1 for the total area of seabed analysed in each year for boxes 1 to 3 by dominant substratum type.

The 2014 Eddystone Reef camera surveys generated 226 images captured from survey boxes 1, 2 and 3 (east to west). Of these images, two were without spatial reference, four had duplicated spatial references, and six images were captured whilst the camera frame was not in contact with the seabed, these images were not analysed. No images were rejected because of poor image quality. The number of tows/images per survey box were; box 1 (tows (n = 8): images (n = 132)), box 2 (tows (n = 4): images (n = 71)) and box 3 (tows (n =1): images (n = 11)), (Figures 2a, 3a, 4a and metadata in Table 2).

The 2015 surveys generated 468 images. Forty images were captured whilst the camera frame was not in contact with the seabed, these images were not analysed. No images were rejected because of poor image quality, duplication of, or missing spatial reference. The number of tows/images per survey box were; box 1 (tows (n = 7): images (n = 134)), box 2 (tows (n = 8): images (n = 148)) and box 3 (tows (n = 8): images (n = 146)), (Figures 2b, 3b, 4b and metadata in Table 2).

The 2016 surveys generated 483 images. Sixty-two images were out of focus, primarily due to delayed triggering of the remote camera, ten images were captured whilst the camera frame was not in contact with the seabed, four images were blank, and one image was without spatial reference. These images (n = 77; 16% of total) were not analysed. The number of tows/analysable images per survey box were; box 1 (tows (n = 8): images (n = 134)), box 2 (tows (n = 7): images (n = 140)) and box 3 (tows (n = 8): images (n = 132)), (Figures 2c, 3c, 4c and metadata in Table 3).

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

The 2017 surveys generated 249 images. Six images were captured whilst the camera frame was not in contact with the seabed, five images were blank, one image was out of focus, one image was a duplicate and one image was of inadequate visual clarity due to suspended sediment. These images (n = 14; 6% of total) were not analysed. The number of tows/analysable images per survey box were; box 1 (tows (n = 4): images (n = 80)), box 2 (tows (n = 5): images (n = 95)) and box 3 (tows (n = 3): images (n = 60)), (Figures 2d, 3d, 4d and metadata in Table 4).

Table 1. Area (m2) of seabed analysed 2014-2017. Area (m2) of analysed seabed is described by box, dominant substratum and year.

Box Substratum 2014 2015 2016 2017

Box 1 CCMS 29.5 29.5 31.25 18.5 RR 3.5 4 2.25 1.5 Box 2 CCMS 16 31.25 33.5 20.5 RR 1.75 5.75 1.5 3.25 Box 3 CCMS 2.75 27.75 24.75 9.25 RR 0 8.75 8.25 5.75

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Figure 2. Eddystone Reef survey strategy for survey box 1 (treatment) 2014-2017. Location of captured images: analysed images (black circle), deleted images (red cross). The total number of validated images captured for each survey box are detailed in the respective figure legend. In all parts survey boxes are drawn as blue polygons (0.44 km2). Areas closed to bottom-towed gear (BTG) within the SAC (grey hatched polygons), reef features (grey polygon) (Axelsson et al. 2006)1. All map parts are drawn to the same spatial scale. Maps drawn to Projected Coordinate System: British National Grid Transverse Mercator.

1. Axelsson, M., Dewey, S., Chaddock, S, and Duke, S (2006) Seastar Survey: Survey of the reef habitat around Eddystone Rocks, Plymouth.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Figure 3. Eddystone Reef survey strategy for survey box 2 (near reference) 2014-2017. Location of captured images: analysed images (black circle), deleted images (red cross). The total number of validated images captured for each survey box are detailed in the respective figure legend. In all parts survey boxes are drawn as blue polygons (0.44 km2). All map parts are drawn to the same spatial scale. Maps drawn to Projected Coordinate System: British National Grid Transverse Mercator.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Figure 4. Eddystone Reef survey strategy for survey box 3 (far reference) 2014-2017. Location of captured images: analysed images (black circle), deleted images (red cross). The total number of validated images captured for each survey box are detailed in the respective figure legend. In all parts survey boxes are drawn as blue polygons (0.44 km2). All map parts are drawn to the same spatial scale. Maps drawn to Projected Coordinate System: British National Grid Transverse Mercator.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Table 2. Metadata for 2014 survey tows. Tows are described by survey box, date, start longitude/latitude, end longitude/latitude, total distance of tow (m: image to image), tow speed (ms-1: mean), tow speed (knots: mean), images captured (n), distance between images (m), maximum and minimum distance between images (m) and total number of species counted. Longitude and latitude are given in decimal degrees WGS84.

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Table 2. Metadata for 2015 survey tows. Tows are described by survey box, date, start longitude/latitude, end longitude/latitude, total distance of tow (m: image to image), tow speed (ms-1: mean), tow speed (knots: mean), images captured (n), distance between images (m), maximum and minimum distance between images (m) and total number of species counted. Longitude and latitude are given in decimal degrees WGS84.

Box Tow ID Date Start lon Start lat End lon End lat Total Tow Tow Images Dist. Max. dist. Min. dist. Species distance speed speed (n) between between between (n) (m) (ms-1) (knots) images (m) images images (total) (mean) (mean) (mean) (m) (m) 1 20150709_Box_1_T1 09/07/2015 -4.338 50.216 -4.335 50.217 269 0.26 0.51 15 19 37 3 71 20150709_Box_1_T3 09/07/2015 -4.338 50.217 -4.336 50.218 190 0.25 0.49 14 15 29 4 50 20150709_Box_1_T5 09/07/2015 -4.337 50.215 -4.334 50.217 355 0.28 0.55 21 18 24 10 47 20150709_Box_1_T8a 09/07/2015 -4.332 50.216 -4.329 50.218 322 0.26 0.51 20 17 23 13 81 20150723_Box_1_T2 23/07/2015 -4.334 50.215 -4.336 50.216 199 0.16 0.31 21 10 11 5 57 20150723_Box_1_T8 23/07/2015 -4.328 50.215 -4.329 50.216 202 0.15 0.29 23 9 12 2 180 20150723_Box_1_T9 23/07/2015 -4.332 50.215 -4.332 50.217 160 0.14 0.26 20 8 12 3 65 2 20150709_Box_2_T1 09/07/2015 -4.363 50.226 -4.362 50.225 194 0.15 0.29 21 10 13 5 44 20150709_Box_2_T2 09/07/2015 -4.364 50.225 -4.364 50.224 191 0.15 0.29 20 10 14 2 93 20150709_Box_2_T3 09/07/2015 -4.366 50.228 -4.366 50.227 29 0.12 0.22 5 7 13 7 12 20150709_Box_2_T3a 09/07/2015 -4.366 50.226 -4.364 50.228 319 0.26 0.50 20 17 24 12 50 20150709_Box_2_T6 09/07/2015 -4.370 50.224 -4.366 50.226 354 0.29 0.55 19 20 41 13 71 20150723_Box_2_T7 23/07/2015 -4.368 50.223 -4.365 50.224 257 0.20 0.39 21 13 24 2 112 20150723_Box_2_T8 23/07/2015 -4.372 50.225 -4.370 50.226 227 0.18 0.35 22 11 18 1 97 20150723_Box_2_T9 23/07/2015 -4.363 50.224 -4.361 50.225 153 0.15 0.28 20 8 12 2 50 3 20150709_Box_3_T2 09/07/2015 -4.504 50.247 -4.506 50.246 228 0.14 0.27 20 12 46 5 58 20150709_Box_3_T3 09/07/2015 -4.498 50.246 -4.499 50.245 132 0.10 0.19 21 7 9 3 27 20150709_Box_3_T4 09/07/2015 -4.500 50.247 -4.497 50.246 221 0.16 0.32 22 11 14 5 60 20150709_Box_3_T5 09/07/2015 -4.505 50.248 -4.503 50.248 163 0.13 0.25 20 9 15 3 116 20150723_Box_3_T6 23/07/2015 -4.507 50.245 -4.506 50.245 79 0.20 0.39 6 16 18 11 16 20150723_Box_3_T6a 23/07/2015 -4.507 50.245 -4.503 50.246 276 0.20 0.40 21 14 25 9 84 20150723_Box_3_T7 23/07/2015 -4.503 50.245 -4.499 50.246 284 0.22 0.44 20 15 22 11 60 20150723_Box_3_T8 23/07/2015 -4.498 50.247 -4.496 50.249 252 0.25 0.48 16 17 21 12 41

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Table 3. Metadata for 2016 survey tows. Tows are described by survey box, date, start longitude/latitude, end longitude/latitude, total distance of tow (m: image to image), tow speed (ms-1: mean), tow speed (knots: mean), images captured (n), distance between images (m), maximum and minimum distance between images (m) and total number of species counted. Longitude and latitude are given in decimal degrees WGS84.

Box Tow ID Date Start lon Start lat End lon End lat Total Tow Tow Images Dist. Max. dist. Min. dist. Species distance speed speed (n) between between between (n) (m) (ms-1) (knots) images (m) images images (total) (mean) (mean) (mean) (m) (m) 1 20160718_Box_1_T1 08/07/2016 -4.337 50.217 -4.334 50.218 183 0.15 0.28 20 10 17 4 75 20160718_Box_1_T2 08/07/2016 -4.337 50.215 -4.334 50.216 233 0.15 0.30 20 12 35 3 29 20160718_Box_1_T3 08/07/2016 -4.332 50.216 -4.337 50.217 366 0.16 0.31 4 122 142 107 19 20160718_Box_1_T4 08/07/2016 -4.328 50.217 -4.330 50.217 181 0.21 0.41 6 36 56 20 30 20161010_Box_1_T1 10/10/2016 -4.329 50.213 -4.330 50.213 58 0.19 0.38 4 19 24 13 31 20161010_Box_1_T2 10/10/2016 -4.328 50.216 -4.336 50.217 585 0.16 0.32 59 10 30 5 162 20161010_Box_1_T3 10/10/2016 -4.331 50.216 -4.332 50.216 94 0.15 0.30 11 9 11 8 38 20161010_Box_1_T4 10/10/2016 -4.332 50.215 -4.332 50.215 71 0.13 0.26 10 8 11 5 44 2 20160718_Box_2_T1 08/07/2016 -4.360 50.225 -4.373 50.226 923 0.35 0.68 42 23 49 15 117 20160718_Box_2_T2 08/07/2016 -4.360 50.224 -4.365 50.224 348 0.27 0.53 11 35 65 10 44 20160718_Box_2_T3 08/07/2016 -4.368 50.225 -4.372 50.227 409 0.27 0.53 17 26 78 5 63 20160718_Box_2_T4 08/07/2016 -4.363 50.225 -4.363 50.225 11 0.17 0.33 2 11 11 11 8 20160718_Box_2_T5 08/07/2016 -4.365 50.226 -4.364 50.227 190 0.18 0.34 17 12 21 8 50 20160718_Box_2_T6 08/07/2016 -4.370 50.225 -4.366 50.227 383 0.21 0.40 31 13 22 8 123 20161010_Box_2_T1 10/10/2016 -4.364 50.224 -4.366 50.225 220 0.18 0.36 20 12 26 8 71 3 20160718_Box_3_T1 08/07/2016 -4.498 50.246 -4.500 50.246 152 0.16 0.31 10 17 37 9 46 20160718_Box_3_T2 08/07/2016 -4.500 50.245 -4.504 50.245 298 0.20 0.39 24 13 30 6 94 20160718_Box_3_T3 08/07/2016 -4.503 50.247 -4.508 50.247 349 0.26 0.51 20 18 33 13 80 20160718_Box_3_T4 08/07/2016 -4.503 50.249 -4.508 50.249 372 0.31 0.60 17 23 73 12 85 20160718_Box_3_T5 08/07/2016 -4.495 50.248 -4.502 50.247 507 0.38 0.75 22 24 97 2 86 20160718_Box_3_T6 08/07/2016 -4.495 50.245 -4.500 50.246 346 0.47 0.91 11 35 80 27 30 20160718_Box_3_T7 08/07/2016 -4.495 50.248 -4.497 50.248 156 0.33 0.63 8 22 39 18 14 20161010_Box_3_T1 10/10/2016 -4.502 50.246 -4.505 50.247 213 0.19 0.36 20 11 13 9 48

EDDYSTONE REEF CAMERA SURVEY SUMMARY REPORT 2014-2017

Table 4. Metadata for 2017 survey tows. Tows are described by survey box, date, start longitude/latitude, end longitude/latitude, total distance of tow (m: image to image), tow speed (ms-1: mean), tow speed (knots: mean), images captured (n), distance between images (m), maximum and minimum distance between images (m) and total number of species counted. Longitude and latitude are given in decimal degrees WGS84.

Image metadata

The proportion of images captured by substratum was variable among survey boxes and years (Figure 5). See Appendix 2 for examples of substratum composition.

Figure 5. Proportion of images, categorised by substratum, per survey box. Substratum is identified as follows: fine (F), medium (M), coarse (C) and rock/reef (R/R). Fine, medium and coarse substratum are representative of circalittoral coarse or mixed sediments (EUNIS habitat codes 5.14 and 5.44 respectively). Rock or reef features are representative of circalittoral rock and other hard substrata (EUNIS habitat code A4).

The number of lasers present per image during the 2014 surveys was variable. Survey box 1 and box 3 had the highest proportion of images with 2 or more lasers present (85.6% and 90.9% respectively), survey box 2 had the highest proportion of images with only 1 laser present (81.7%). The number of lasers present per image during the 2015, 2016 and 2017 surveys was highly consistent. For 2015, 100% of all images from survey boxes 1 and 2, and 99.3% from survey box 3 had 3 or more lasers present. For 2016, 100% of all images from survey box 1, and 99.3% and 99.2% from survey boxes 2 and 3 respectively had 3 or more lasers present. For 2017, 100% of all images from survey boxes 1 and 2, and 98.3% from survey box 3 had 3 or more lasers present.

Image quality across all survey boxes during the 2014 surveys was predominately moderate/good with less than ~10% of images per survey box being classified as ‘poor’. For 2015 and 2016 over 99%, and for 2017 over 96%, of all images were classified as moderate to good. See Appendix 2 for examples of image quality.

Species composition

Among survey boxes, rock and reef features were predominantly host to mixed Bryozoa, Cnidaria and Porifera communities. Composition of species on circalittoral coarse and mixed sediments among boxes and years was mixed. In general, box 2 hosts a greater relative abundance of crustacea (crab, hermit crab and squat lobster) and scallops than boxes 1 and 3 (Figures 6-11). Box 2 also hosts the greatest abundance of spirorbids, this potentially reflects the coarser nature of the substratum which is dominated by medium to coarse cobble and shell.

Figure 6. Relative abundance of species (proportion) for survey box 1 (2014-2017) on circalittoral coarse or mixed sediments (CCMS: EUNIS habitat codes 5.14 and 5.44). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box by year. Phyla are shaded in accordance with the figure legend.

Figure 7. Relative abundance of species (proportion) for survey box 1 (2014-2017) on rock/reef features (R/R: circalittoral rock and other hard substrata EUNIS habitat code A4). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box. Phyla are shaded in accordance with the figure legend.

Figure 8. Relative abundance of species (proportion) for survey box 2 (2014-2017) on circalittoral coarse or mixed sediments (CCMS: EUNIS habitat codes 5.14 and 5.44). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box. Phyla are shaded in accordance with the figure legend.

Figure 9. Relative abundance of species (proportion) for survey box 2 (2014-2017) on rock/reef features (R/R: circalittoral rock and other hard substrata EUNIS habitat code A4). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box. Phyla are shaded in accordance with the figure legend.

Figure 10. Relative abundance of species (proportion) for survey box 3 (2014-2017) on circalittoral coarse or mixed sediments (CCMS: EUNIS habitat codes 5.14 and 5.44). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box. Phyla are shaded in accordance with the figure legend.

Figure 11. Relative abundance of species (proportion) for survey box 3 (2014-2017) on rock/reef features (R/R: circalittoral rock and other hard substrata EUNIS habitat code A4). Species identified by species description grouped by Phyla. Each bar represents the total number of images (n) with species present expressed as a proportion of the total number of images (n) captured within the survey box. Phyla are shaded in accordance with the figure legend.

Species abundance in colonised images (selected species)

For six selected species we determined the mean number of individuals present per image (where at least a single organism of that species was detected) by box and year. Three species were chosen for each major substratum type (CCMS and RR). For CCMS, species were selected which may infer seabed integrity and/or where it was considered increasing numbers might represent spreading/re-colonisation of species. As such, knowledge regarding the breeding biology has not been explicitly incorporated but rather we have considered that spreading might indicate increased seabed stability following a reduction in scallop dredging.

Currently, these patterns through time remain too short to robustly test statistically. However, CCMS species abundance appear stable; while greater variation is present in the RR species, which may in part reflect the varying survey effort through years on this habitat type.

Figure 12. Species abundance (mean ± se) for survey boxes 1,2 and 3 (2014-2017) on circalittoral coarse or mixed sediments (CCMS: EUNIS habitat codes 5.14 and 5.44). Abundance is calculated as mean ± se of recorded individuals (n) per total number of colonised image for that species by box and by year. Standard error bars are not drawn when the sum of individual species per box is the same as the count of colonised image or where there is only one colonised image. See Appendix 3 for data table.

Figure 13. Species abundance (mean ± se) for survey boxes 1,2 and 3 (2014-2017) on rock/reef features (R/R: circalittoral rock and other hard substrata EUNIS habitat code A4). Abundance is calculated as mean ± se of recorded individuals (n) per total number of colonised image for that species by box and by year. Standard error bars are not drawn when the sum of individual species per box is the same as the count of colonised image or where there is only one colonised image. See Appendix 3 for data table.

Discussion

The 2015, 2016 and 2107 Eddystone drop-down camera surveys produced 428, 406 and 235 analysable images respectively. In contrast, the 2014 surveys gathered 214 analysable images. The 2015 surveys were conducted over a short time-frame (14 days) in July. Due to operational difficulties, the surveys for 2014, 2016 and 2017 were split between the months of June/July (42 days), July/October (94 days), and July/August (52 days) respectively. In 2014 41 analysable images were recorded in June and 173 in July, in 2016 282 analysable images were recorded in June and 124 in October, in 2017 60 analysable images were recorded in July and 175 in August. The 2015 and 2016 surveys provided for the most spatially extensive and balanced survey effort across survey boxes.

There was a marked improvement in the number of lasers present among survey years, with all images in 2015, 2016 and 2017 having 2 or more lasers present. This compared with 86%, 18% and 91% for boxes 1, 2 and 3 respectively in year 2014. Similarly, there was a marked improvement in image quality with less than 0.5% of all images captured in 2015 and no images in 2016 or 2017 categorised as poor, this compared with ~10% in 2014. The 2015 survey protocol saw refinements made to the laser system and lighting rig as well as an improved 'trigger response' of the remote camera. These latter modifications combined to provide sharper images with reduced movement of the camera frame at the moment of image capture. This was also reflected in image capture for 2016 and 2017.

Our analysis indicates that rock and reef features are present within all survey boxes. Furthermore, substratum composition is similar between survey boxes 1 and 3 being a mosaic of sediment and coarser material, whilst survey box 3 substratum is largely dominated by medium/coarse cobble and shell. Among survey years and boxes, rock and reef features were predominantly host to mixed Bryozoa, Cnidaria and Porifera communities. Composition of species on circalittoral coarse and mixed sediments among boxes and years was mixed. In general, box 2 hosts a greater relative abundance of crustacea (crab, hermit crab and squat lobster) and scallops than boxes 1 and 3 (Figures 6- 11). Box 2 also hosts the greatest abundance of spirorbids, this potentially reflects the coarser nature of the substratum.

The 2015, 2016 and 2017 surveys have robustly advanced the preliminary survey work of 2014 and have continued to build an extensive library of seabed images for the Eddystone Reef complex. During this time the methods associated with species identification and enumeration as well as data processing and manipulation protocols have been developed and refined. Further surveys proposed for 2018-2019, using the same survey methodology adopted for 2015, 2016 and 2017, will enable the ongoing compilation of a comprehensive database of images to be constructed. As such, once a temporally robust and spatially explicit dataset has been gathered, statistical approaches may be applied to explore seabed

community diversity and composition that may offer insight into detectable change in seabed communities between areas that are closed, and those that remain open, to bottom-towed fishing gear.

Appendices Appendix 1: Species identification confidence

Low to medium confidence High confidence

(a)

(b)

(c)

(d)

(a) gas mantle sea squirt (Corella parallelogramma), (b) king scallop (Pecten maximus), (c) cup coral (Caryophyllia sp.) and (d) dead men’s fingers (Alcyonium digitatum). 31

Appendix 2: Substratum and image quality

Appendix 3: Data table for Figs. 12 and 13

Substratum Species Year Sum of organisms Count of colonised images Box 1 Box 2 Box 3 Box 1 Box 2 Box 3 CCMS anemone 2014 6 3 NA 6 2 NA 2015 12 14 15 9 14 15 2016 12 18 10 11 16 10 2017 6 5 NA 6 5 NA

cup coral 2014 12 NA NA 9 NA NA 2015 57 30 6 30 4 4 2016 47 5 24 33 5 3 2017 21 5 119 14 3 10

scallop 2014 2 7 1 2 7 1 2015 7 54 9 6 41 9 2016 10 48 7 10 37 6 2017 5 27 3 5 20 3

RR cup coral 2014 187 142 NA 13 6 NA 2015 207 715 1150 16 23 33 2016 122 188 928 7 6 30 2017 62 583 747 5 13 23

dead men's fingers 2014 53 38 NA 10 2 NA 2015 9 60 19 6 13 10 2016 12 14 6 5 2 6 2017 3 77 35 2 10 14

pink sea fans 2014 58 15 NA 12 6 NA 2015 52 64 84 16 17 32 2016 18 4 57 8 1 29 2017 4 13 51 3 8 25