2008 SNH Report 346 Mapping Habitats & Species Lamlash CMCA

Scottish Natural Heritage Commissioned Report 346 Mapping of Marine Habitats and Species within the Community Marine Conservation Area at Lamlash Bay, 2008

COMMISSIONED REPORT

Commissioned Report No.346 Mapping of Marine Habitats and Species within the Community Marine Conservation Area at Lamlash Bay, 2008

For further information on this report please contact: Laura Steel Scottish Natural Heritage Great Glen House INVERNESS IV3 8NW Telephone: 01463 725236 E-mail: [email protected]

This report should be quoted as:

Axelsson, M., Dewey, S, Plastow, L. and Doran, J. (2009). Mapping of marine habitats and species within the Community Marine Conservation Area at Lamlash Bay. Scottish Natural Heritage Commissioned Report No.346.

This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be taken as the views and policies of Scottish Natural Heritage.

COMMISSIONED REPORT

Summary

Mapping of Marine Habitats and Species within the Community Marine Conservation Area at Lamlash Bay, 2008 Commissioned Report No. 346 Contractor: Seastar Survey Ltd. Year of publication: 2009

Background In September 2008 a No Take Zone (NTZ) was established in Lamlash Bay (Isle of Arran, North Ayrshire) in Scotland following a consultation for a fishery order (under the Inshore Fishing (Scotland) Act 1984). The proposed NTZ was passed by the Scottish Parliament prohibiting all sea fishing within the NTZ. Scottish Natural Heritage has a commitment to contribute to the monitoring of the No Take Zone in Lamlash Bay and the purpose of the current study is to initiate the monitoring of the Lamlash Bay NTZ to establish the future success of the management measures in delivering benefits to both the biodiversity and the scallop fishery in the bay. The main aims of the current study were to carry out an acoustic mapping survey with ground-truthing (camera deployments and sediment sampling) to create maps of the habitats and biotopes within the site in a Geographical Information System (GIS). This report is part 1 of 2 and details survey data attained in 2008, only.

Main findings • The ground-truthing of the sidescan sonar data revealed a heterogeneous sediment environment with sand dominating the central and southern Lamlash Bay and mixed coarse sediments dominating the northern Lamlash Bay and North Channel. • All Lamlash Bay NTZ Day grab locations were classified as ‘sand’ according to the Folk sediment classification system (greater than 80%); with fine and very fine sand being the dominant ‘sand’ categories. • Two biotopes have tentatively been designated among the NTZ Day grab locations as SS.SSa.CMuSa.(AalbNuc) and SS.SMx.CMx.(MysThyMx). • Six biotopes were recognised during the ground-truthing (using drop-down camera) of sidescan sonar data: CR.LCR.BrAs.AmenCio, CR.LCR.BrAs.AmenCio.Bri, SS.SMx.CMx.ClloMx(Nem), SS.SMPMrl, SS.SMu.CSaMu.(AfilMysAnit), SS.SSa.CMuSa.(AbraAirr). • Maerl beds, dominated by Phytomatolithon calcareum, were identified in the northern Lamlash bay, North Channel and the Lamlash Outer regions. • Based on comparisons with the few previous studies the sediment environment and the faunal communities are similar overall. • Recommendations are made regarding future monitoring including repeat drop- down camera (still photography and video) and sediment sampling surveys at 2 year intervals.

For further information on this project contact: Laura Steel, Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW Email: [email protected] Tel: 01463 725236 For further information on the SNH Research & Technical Support Programme contact: Policy & Advice Directorate Support, SNH, Great Glen House, Leachkin Rd, Inverness, IV3 8NW Tel: 01463 725000 or [email protected]

Acknowledgements

We would thank the captain and crew of the vessel Alba na Mara for their help and positive attitude throughout the survey period in Lamlash Bay in October 2008. We would also like to thank staff at Scottish Natural Heritage for their support and feedback throughout the project.

CONTENTS

SUMMARY

1 INTRODUCTION 1

1.1 Project background 1 1.2 The environment 3 1.2.1 Geology and the sedimentary environment 3 1.2.2 The physical environment 4 1.2.3 Biological distributions 4

2 METHODOLOGY 5 2.1 Acoustic survey 5 2.1.1 Horizontal control 6 2.1.2 Vertical control 7 2.1.2.1 Tides 7 2.1.2.2 Split beam echosounder 7 2.1.3 Vessel motion reference 7 2.1.4 Sidescan sonar 7 2.1.5 Weather conditions 8 2.1.6 Processing and charting 9 2.2 Drop-down camera survey methodology 9 2.2.1 Drop-down camera system 9 2.2.2 Camera operation and deployment 10 2.2.3 Data handling 11 2.3 Video and photographic analysis 11 2.3.1 Analysis of the photographs and video records 11 2.3.1.1 Semi-quantitative analysis of the video footage 11 2.3.1.2 Quantitative analysis of the stills photographs 12 2.4 Sediment sampling 12 2.5 Data analysis 14 2.6 Survey limitations 15 2.6.1 Survey vessel 15 2.6.2 Obstructions 15

3 RESULTS 15 3.1 Acoustic analysis 15 3.1.1 Target 1 - anchor sinkers 16 3.1.2 Target 2 - anchor drag marks 17 3.1.3 Target 3 - scallop dredge marks 18 3.1.4 Target 4 - exposed bedrock 18 3.1.5 Target 5 - Deacon Rock 19 3.1.6 Target 6 - sediment furrows 20 3.1.7 Target 7 - low backscatter return (sand) 20 3.1.8 Target 8 - mottled high and low backscatter 21 3.1.9 Target 9 - mottled high and low backscatter 21 3.1.10 Target 10 - area of seabed with Maerl 22 3.2 Photographic and video analysis – ground-truthing 23 3.2.1 Ground-truthing of the sidescan sonar imagery 23 3.2.1.1 Target 5 - Deacon Rock 23 3.2.1.2 Target 7 - low backscatter return 24 3.2.1.3 Target 8 - mottled high and low backscatter 24 3.2.1.4 Target 9 - mottled high and low backscatter 25 3.2.1.5 Target 10 - area of seabed with maerl 25

3.2.2 General descriptions of the biological communities in Lamlash Bay 26 3.2.2.1 Central and southern Lamlash bay 26 3.2.2.2 Northern Lamlash Bay and North Channel 28 3.2.2.3 Outer Lamlash Bay 31 3.2.2.4 Scallops and other noteworthy species 32 3.2.2.5 Maerl beds 35 3.2.2.6 Brittlestar beds 36 3.3 Sediment samples 37 3.3.1 Particle Size Analysis 38 3.3.2 Macrofaunal distributions 39 3.3.2.1 Abundance 40 3.3.2.2 Diversity 41 3.3.2.3 Macrofaunal composition 41 3.3.3 Comparisons between macrofaunal trends and the sediment data 45 3.3.4 Biotope classification of the 2008 Lamlash Bay Day grab samples 46 3.4 The seabed environment in Lamlash Bay 47

4 DISCUSSION 52 4.1 Survey methodology 52 4.2 Survey limitations 52 4.2.1 Survey extent 52 4.2.2 Discrepancies between the sidescan sonar and photographic survey results 53 4.3 Confidence assessment 53 4.4 Comparisons with previous studies 54 4.4.1 Lamlash Bay rocky reefs 54 4.4.2 Lamlash Bay maerl beds 55 4.4.3 Other fauna and flora in Lamlash Bay 55 4.4.4 Biotope distribution in Lamlash Bay 56 4.5 Recommendations for future monitoring at Lamlash Bay 57 4.5.1 Requirement for immediate additional survey effort 57 4.5.2 Future monitoring in Lamlash Bay 58 4.5.2.1 Sediment character 58 4.5.2.2 Distribution of biotopes 58 4.5.2.3 Extent of sub-features 58 4.5.2.4 Species composition and population measures 58

5 CONCLUSIONS 59

6 REFERENCES 60 6.1 General references 60 6.2 References used for video and still photography identification 62

APPENDICES A01. Survey equipment specification. A02. Navigation checks and tidal curves A03. Field survey logs A04. Particle Size Analysis (PSA) A05. Modified FOLK sediment classification A06. Lamlash Bay Day Grab sample species list A07. Faunal densities for noteworthy species (from still photography)

DRAWINGS (AO)

Drawing 151.01. Lamlash Bay sidescan sonar mosaic and bathymetry.

Drawing 151.02. Sidescan sonar mosaic with biotope classification from still photographs.

Drawing 151.03. Sidescan sonar mosaic with sediment classification from still photographs.

Drawing 151.04. Sidescan sonar mosaic with biotope classification polygons.

Drawing 151.05. Sidescan sonar mosaic with biotopes from photographs and polygons.

LIST OF FIGURES

Figure 1. Lamlash Bay located on the east coast (Firth of Clyde) of the Isle of Arran in North Ayrshire, Scotland.

Figure 2. Lamlash Bay No Take Zone boundary.

Figure 3. Seasearch survey sites in Lamlash Bay.

Figure 4. The bathymetric survey coverage (lines) for the Lamlash Bay habitat mapping survey 2008 (with the four main areas illustrated by the coverage).

Figure 5. Sidescan sonar coverage for the Lamlash Bay habitat mapping survey 2008.

Figure 6. Camera system mounted on a similar seabed frame to that used during the Lamlash Bay survey.

Figure 7. Drop-down camera sampling locations (tracks) for the Lamlash Bay habitat mapping survey 2008.

Figure 8. Sediment sampling locations for the Lamlash Bay habitat mapping survey 2008.

Figure 9. Sidescan sonar image with selected targets to illustrate some of the features identified in Lamlash Bay.

Figure 10. Anchor sinkers seen in the southern section of Lamlash Bay (located approximately at East (X): 204779.6 and North (Y): 629190.2).

Figure 11. Anchor drag marks in the southern section of Lamlash Bay (located approximately at East (X): 204804.31 and North (Y): 629718.87).

Figure 12. Scallop dredge marks in the southern section of Lamlash Bay (circular pattern centred on East (X): 205270.52 and North (Y): 629791.71).

Figure 13. Exposed bedrock near the shallow sill in North Channel in Lamlash Bay (located approximately at East (X): 206105.47 and North (Y): 632224.95).

Figure 14. Deacon Rock in Lamlash Bay.

Figure 15. Sediment furrows in the centre of Lamlash Bay.

Figure 16. An area of low backscatter return in the south of Lamlash Bay.

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Figure 17. An area of high mottled backscatter return in the south of Lamlash Bay (located at East (X): 205110.26 and North (Y): 628864.17).

Figure 18. An area of high, low and mottled backscatter illustrating cobbles, boulders and rocks surrounded by sand (located at East (X): 204182.71 and North (Y): 630457.02).

Figure 19. An area of mottled backscatter to the North West of Lamlash Bay where maerl is present (located at East (X): 204581.00 and North (Y): 631678.00).

Figure 20. Ground-truthing of target 5 - Deacon Rock (photograph LNC07_26 and 32).

Figure 21. Ground-truthing of target 7 - low backscatter return (photograph LSC03_20).

Figure 22. Ground-truthing of target 8 (photographs LSC04_49 and LNC05_48).

Figure 23. Ground-truthing of target 9 (photographs LNC10_21 and LNC08_20).

Figure 24. Ground-truthing of target 10 (photographs LNC11_10).

Figure 25. Photographs from the southern and central regions of Lamlash Bay (LSC01_07, LSC02_29, LSC06_26 and LSC07_39).

Figure 26. Photographs from the northern Lamlash Bay and North Channel areas of Lamlash Bay (LNC03_09, LNC05_04, LNC07_35, LNC10_02, LNC10_06, LNC11_06, LNC11_20, LNC12_03).

Figure 27. Photographs from the Outer Lamlash Bay area (LNC01_09, LOC01_35, LNC01_56, LNC01_71, LNC02_17, LNC03_04).

Figure 28. Examples of scallops observed in Lamlash Bay.

Figure 29. Maerl beds observed in and around Lamlash Bay.

Figure 30. Brittlestar beds in Lamlash Bay (LNC08_19, LNC08_20, LOC3_ 08 and LSC01_55).

Figure 31. Cumulative percentage sediment weight at the NTZ locations in Lamlash Bay.

Figure 32. Cluster analysis of the 2008 Lamlash Bay macrofaunal Day grab data.

Figure 33. Ordination analysis of the 2008 Lamlash Bay macrofaunal Day grab data (all 10 locations).

Figure 34. Further ordination analysis of the 2008 Lamlash Bay macrofaunal Day grab data (the 7 locations grouped).

Figure 35. Biotope complex distribution in Lamlash Bay (from the video and stills photography analysis) overlaying the sidescan sonar imagery.

Figure 36. Biotope complex distribution within the NTZ in Lamlash Bay (from the video and stills photography analysis) overlaying the sidescan sonar imagery.

Figure 37. The biotope distribution in Lamlash Bay from photographic ground-truthing.

Figure 38. The sediment distribution in Lamlash Bay from photographic ground-truthing.

LIST OF TABLES

Table 1. Coordinates of Lamlash Bay No Take Zone boundary (Scottish Government, 2008)

Table 2. Lamlash Bay survey areas

Table 3. Summary of video and still photography data collected during the 2008 Lamlash Bay surveys.

Table 4. Summary of the video and photographic analyses with the main substrata, fauna and biotope in central and southern Lamlash Bay.

Table 5. Summary of the video and photographic analyses with the main substrata, fauna and biotopes (mixed sediments are muddy, gravelly sands with shell material) in northern Lamlash Bay and North Channel.

Table 6. Summary of the video and photographic analyses with the main substrata, fauna and biotopes (mixed sediments are muddy, gravelly sands with shell material) in Outer Lamlash Bay.

Table 7. The approximate densities (ind/100 m2) of scallops and two other species present in the still photographs from the 2008 Lamlash Bay survey.

Table 8. The approximate densities (ind/100 m2) of scallops and two other species present in the video footage from the 2008 Lamlash Bay survey.

Table 9. Day grab sampling locations.

Table 10. Summary of the Particle Size Analysis (sediment weight by percentage) from the NTZ in Lamlash Bay.

Table 11. Total percentage sediment weight (brown: ‘gravel’; yellow: ‘sand’; pink: ‘silt’) of the Day grab samples at the NTZ locations in Lamlash Bay (NB. processing differential resulting in total percentage being in excess of / less than 100%).

Table 12. Total number of individuals of the most abundant taxa/species present in the 2008 Lamlash Bay survey (rank order).

Table 13. Total number of individuals (N), number of species (S), Margalef’s species richness (d), Pielou’s equitability index (J) and Shannon-Wiener diversity index (H’) for all the samples in the 2008 Lamlash Bay Day grab survey.

Table 14. SIMPER analysis of the 2008 macrofauna in Lamlash Bay.

Table 15. SIMPER analysis of taxa within the ‘fine’ cluster groups in the 2008 Lamlash Bay survey.

Table 16. Results from the Spearman rank correlation coefficient analysis comparing the faunal data with the sediment data collected at Lamlash Bay 2008.

Table 17. Summary of the biotope complexes / biotopes for the 2008 Lamlash Bay Day grab samples.

Table 18. Lamlash Bay monitoring attributes.

Data Storage and display

All of the data collected during the survey have been stored in the following formats:

 Data logs have been created in Excel and Word documents.  All still photographs and images included in the report have been stored as JPEG.  Raw video data have been stored digitally using MiniDV tapes  Edited video data supplied as MPEG files on DVD.  All bathymetry data have been stores in ASCII text format (X, Y, Z).  Raw sidescan sonar data have been stored in HyPack and XTF format.  Mosaic sidescan sonar data have been stored in GeoTiff format.  The GIS data have been stored in ArcView 9.2.

These are kept by Scottish Natural Heritage.

1 INTRODUCTION

1.1 Project background

Seastar Survey Ltd. was contracted by Scottish Natural Heritage (SNH) to conduct a habitat mapping survey of Lamlash Bay, Isle of Arran (figure 1). The survey of the bay follows a consultation for a fishery order (under the Inshore Fishing (Scotland) Act 1984) to establish a No Take Zone (NTZ) in Lamlash Bay. On 20th September 2008 the proposed NTZ was passed by Scottish Parliament prohibiting all sea fishing within the NTZ (figure 2 and table 1).

The aim of the survey was to map the habitats and biotopes to provide a comprehensive baseline survey of the seabed in Lamlash Bay. The survey will form the baseline for future monitoring of the area to establish the success of the management measure in delivering benefits to both the biodiversity of the bay and the scallop fishery in the area. The survey area encompasses the whole of Lamlash Bay and an area outside the bay extending approximately 1 mile beyond the northern and southern entrances of the bay and seawards to the 30 m contour (figure 1), with the NTZ given the highest priority.

Figure 1. Lamlash Bay located on the east coast of the Isle of Arran (Firth of Clyde) in North Ayrshire, Scotland.

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

Figure 2. Lamlash Bay No Take Zone boundary.

Table 1. Coordinates of Lamlash Bay No Take Zone boundary (Scottish Government, 2008)

Location Latitude Longitude Mount Pleasant Farm 55˚ 32.603’ N 006˚ 06.512’ W Holy Isle West 55˚ 31.556’ N 005˚ 05.216’ W Holy Isle East 55˚ 31.876’ N 005˚ 04.304’ W Hamilton Rock 55˚ 33.000’ N 005˚ 04.823’ W Clauchlands Point 55˚ 33.002’ N 005˚ 04.957’ W

In order to record and characterise the habitats in Lamlash Bay, Seastar Survey Ltd. undertook an acoustic and a ground-truthing survey (sediment sampling and video/still photography surveys). The aim of the acoustic element of the survey was to identify different backscatter returns and describe as well as delineate the extent of the various seabed habitat types occurring in and around Lamlash Bay.

A digital sidescan sonar mosaic, in conjunction with single beam echo sounder derived bathymetry, provided the initial broadview to map the substrates present throughout the survey area. A certain amount of interpolation was required due to the constraints of the available budget preventing total coverage of the entire survey area.

The aim of the ground-truthing element of the survey was to provide a description of the richness and diversity of the habitats on both rocky reef and the softer sediments. The biotope distribution and species composition was developed through interpretation of drop- down video footage and digital still photography, taken after evaluation of the sidescan mosaic. Sediment samples (Day grabs) were also processed and analysed to ground-truth the sidescan sonar data as well as describe and quantify the infaunal communities.

The results of all elements of the survey were used to create a Geographical Information System (GIS) which enabled a high level of processing, interpretation and display of the sidescan sonar mosaic, bathymetry, substrata types, biotopes and the digital photography.

1.2 The environment

Lamlash Bay is located on the east coast of the Isle of Arran in North Ayrshire, Scotland. Arran is the largest island in the Firth of Clyde, the most southerly fjord in the northern hemisphere (COAST, 2005). Arran is sheltered from the Atlantic by the Kintyre Peninsula and separated from mainland Scotland by the Firth of Clyde to the east and the Sound of Bute and the mouth of Loch Fyne to the north (Gazetteer for Scotland, 2008). The island is 36 km in length and 22 km wide (COAST, 2005).

Lamlash Bay is approximately 5 km across, bounded by the headlands of Clauchlands Point to the north and Kingscross point to the south (COAST, 2005; Gazetteer for Scotland, 2008). Over half of the bay is occupied by Holy Island which is approximately 3 km long and 1.5 km wide (COAST, 2005; Gazetteer for Scotland, 2008).

1.2.1 Geology and the sedimentary environment

There is limited published information regarding the seabed environment in Lamlash Bay, however, the northern and southern margins of the bay are dominated by rocky coastlines with sublittoral rock being present along the northern coast and the northern channel (Duncan, 2003). The south-western coast of Holy Island consists of a steep rocky slope that descends to 20 m below chart datum (Duncan, 2003).

On admiralty charts the seabed within the bay is generally dominated by mud and sand with additions of broken shell particularly in the southern area of Lamlash Bay and along the western side of Holy Island. The North Channel and the outer reaches of the survey area are dominated by mixed sediments (sand, mud, broken shell and gravel). These records seem to be in overall agreement with the observations made by Duncan (2003), reporting the sediment to be primarily composed of soft sediments with sand being the most common sediment type. Areas of mixed sediment (rock, cobble and mud) and other areas dominated by boulders have also been identified (see Duncan, 2003), the latter being a feature not identified on the admiralty chart.

1.2.2 The physical environment

The maximum water depth in Lamlash Bay is 43 m below chart datum (admiralty charts) with the majority of the area being > 20 m deep below chart datum. Shallower sills exist at the northern and southern entrances to the bay. The sill at the southern entrance of the bay has a maximum water depth of 25 m below chart datum, at the northern entrance to the bay water depths are recorded as 11.3 m below chart datum (Seasearch 2003, COAST 2005).

Current speeds range from approximately 0.5 knots (neap tides) to 0.75 knots (spring tides) at the entrance of the North Channel and from 0.75 knots (neap tides) to 1.5 knots (springs) at the entrance of the South Channel.

1.2.3 Biological distributions

There is a limited amount of published information regarding the biological distributions in Lamlash Bay and prior to 2003 no records existed for Lamlash Bay within the Marine Nature Conservation Review (MNCR) database (now recorded as NBN Marine Recorder) (Duncan, 2003; COAST, 2005). In 2003, however, Seasearch divers surveyed 21 sites in Lamlash Bay (location of survey sites are shown in figure 3) to create a basic sublittoral baseline for the area (Duncan, 2003). The sites surveyed are marked by flags with small blue circles at the base of the flags illustrating the exact position of the site. Sites with maerl are highlighted in purple and scallops (abundance estimated as ‘common’ and/or noteworthy on the Seasearch forms) in brown (locations 6-8, 10, 12, 14 and 20). Sites with both maerl and scallops (‘common’) were recorded in blue (sites 7 and 16) and sites with both seagrass and maerl were recorded in green (2). All other sites were recorded in orange (see Duncan (2003) for further details).

Figure 3. Seasearch survey sites in Lamlash Bay (from Duncan, 2003).

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

Of particular note is the presence of maerl and seagrass (Zostera sp.) beds in the North Channel as well as the presence of ‘reefs’ (e.g. Deacon Rock). Although none of the species recorded in Lamlash Bay are listed as Annex II species in the EC Habitats Directive, both maerl and Zostera sp. are both listed on the UK Biodiversity Action Plan (UKBAP) Habitat Action Plan as priority habitats (UKBAP, 2008). In addition to being listed as a priority habitat on the UKBAP’s Habitat Action Plan, maerl beds are covered by four different habitat types of Annex I of the EC Habitats Directive ‘sandbanks which are slightly covered by seawater at all times’, ‘large shallow bays and inlets’; ‘estuaries’ and the priority habitat ‘lagoons’ (UKBAP, 2008).

Apart from the ecologically important species such as Phymatolithon (maerl) and Zostera sp. (eelgrass), other taxa recorded in the bay (see Duncan, 2003) include Cerianthus lloydii, Metridium senile, Echinus esculentus and species in the subphylum Pisces (fish); dogfish, conger eels (Conger conger), leopard-spotted gobies (Thorogobius ephippiatus), pipefish (Syngnathinae), gurnards (Triglidae), dragonets (Callionymus lyra) and plaice (Pleuronectes platessa) as well as commercially important species such as scallops (Pectinidae), edible crabs (Cancer pagurus) and flatfish (Pleuronectiformes).

2 METHODOLOGY

The field work (acoustic and biological surveys) was undertaken between the 13th and 21st October 2008 with all survey operations conducted from the Fisheries Research Services (FRS) survey vessel ‘Alba na Mara’. The survey mobilisation and de-mobilisation took place in Ardrossan Harbour, Scotland on 13th October and 21st October respectively. During the survey the vessel anchored overnight in either Lamlash Bay or Brodick Bay.

2.1 Acoustic survey

The survey was carried out using a Leica 1200 RTK Rover GPS system, a split beam echosounder Simrad EK60 and a sidescan sonar system EdgeTech FS 4200 dual frequency (see appendix 1 for detailed equipment specifications).

The acoustic survey area was divided into four main areas of planned acoustic lines (figure 4 and table 2) to simplify survey operations. SNH defined the area within the NTZ as the priority survey area. The survey effort was structured to ensure that the acoustic and ground- truthing was completed in its entirety within the NTZ in the event that the survey work was delayed preventing the completion of the survey work in the remainder of the area.

Table 2. Lamlash Bay survey areas

Survey area Number of lines Line numbers Total lines length (km) Lamlash North 15 101-115 48.882 Lamlash South 19 201-219 59.994 Lamlash Outer 10 401-410 58.496 Deacon Rock 11 301-311 11.807 Total line kms 179.179

Figure 4. The bathymetric survey coverage (lines) for the Lamlash Bay habitat mapping survey 2008 (with the four main areas illustrated by the coverage).

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

2.1.1 Horizontal control

Horizontal control was achieved using a Leica Real Time Kinematic (RTK) GPS (GX1230 Real Time Rover System). The GPS antenna was mounted on the handrail on the upper deck above the bridge to ensure a signal could be received from the maximum number of satellites available.

The GPS obtained a satellite derived position in WGS84 latitude and longitude which was recorded using the Hypack 2008 survey management software. A data transformation was undertaken within the Hypack software using the Ordnance Survey model OSTN02 to convert from WGS84 latitude and longitude to OSGB36 easting and northing.

A known position within Ardrossan Harbour was obtained from the Ordnance Survey in OSGB36 grid coordinates. A navigation check was then carried out against that known position at the start and the end of the survey to check the accuracy of the RTK GPS signal (see navigation checks in appendix 02).

2.1.2 Vertical control

2.1.2.1 Tides

Tide corrections were achieved via the vertical component of the RTK GPS. The raw bathymetric soundings produced by the echosounder were reduced relative to Ordnance Datum Newlyn (ODN) using the Ordnance Survey OSGM02 model within Hypack. This allowed for the tidal component to be removed from the raw soundings in real-time (see example of tidal curve in appendix 02).

2.1.2.2 Split beam echosounder

Vertical control for the survey was achieved using the Alba na Mara’s Simrad EK60 scientific split beam echosounder (38/200 kHz) with the coverage of the survey illustrated in figure 4. The vessels echosounder transducers are pole mounted in a pod fitted to a shaft which enabled the pod to be deployed to 1 m below the keel to improve acoustic performance. When the echosounder pole was down the transducers were approximately 5.25 m below the sea surface.

It was intended that the high frequency (200 kHz) channel would be used for the survey. However, the data provided by the high frequency channel was found to experience signal loss when the vessel was moving; therefore the low frequency (38 kHz) data was recorded for the duration of the survey.

The speed of sound through the water column was measured each day using a Marimatech HMS 1820-P CTD. Additional sound velocity profiles were taken when the survey vessel moved to a different survey area. The sound velocity profiles have been applied to the bathymetric data during processing within the Hypack survey management software.

The bathymetric soundings were reduced relative to ODN to account for the effect of tide in real-time within Hypack, via the vertical component of the RTK GPS. Hypack applied the real time corrections using the Ordnance Survey OSGM02 model.

2.1.3 Vessel motion reference

Possible errors in the bathymetric data relating to vessel motion were minimised by the use of a TSS CMS 25 Compact Motion Sensor, to account for any vessel motion to an accuracy of ±5 cm. Corrections due to vessel motion have been applied during processing using the Hypack software.

2.1.4 Sidescan sonar

Seabed backscatter data was collected using an EdgeTech 4200-FS dual frequency (120/410 kHz) sidescan sonar. During the survey the unit was operated using the high frequency at 410 kHz. The system comprised a towfish, a slip-ring winch carrying 700 m of coax cable and transceiver. The sidescan data was viewed in real-time through Hypack. Heading and layback information were also provided through Hypack. Data was recorded in HS2 format (Hypack sidescan data file).

The line spacing was set at 50 m with a range of 50 m (covering 50 m either side of the fish – 100m swath). The line spacing allowed for 100 % overlap of the sidescan data with adjacent lines. The towfish was deployed from the Alba na Mara’s CTD winch. The towfish was lowered into the water by the ships crew. Once the towfish was at the sea surface control of

the winch was transferred to winch controls in the survey lab, which were operated by the surveyor. The sidescan was towed at speeds of 4-5 knots.

The sidescan sonar survey resulted in a coverage illustrated in figure 5 (see survey limitations below).

Figure 5. Sidescan sonar coverage for the Lamlash Bay habitat mapping survey 2008.

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

2.1.5 Weather conditions

The weather conditions were overall suitable for survey operations to take place throughout the survey period with the only exception being 19 October 2008 when weather downtime was incurred as a result of strong wind (Force 7-8), rough seas (moderate – rough), heavy rain and poor visibility. In these conditions it was deemed unsafe for the vessel to continue with camera work or to carry out grabbing and survey operations were ceased for the remainder of the day.

2.1.6 Processing and charting

Processing of the bathymetric data was undertaken using the post processing tools within the survey management software. This was undertaken with reference to the echo sounder paper trace records as part of our quality control procedures. The processing of the data involved editing out the water column, the removal of spikes and other erroneous points from the data and the reduction of the depths using corrected data acquired from the RTK. The data were then imported into a ArcView GIS for display and interpretation.

The sidescan sonar data were initially processed and mosaiced within the survey management software. This involved trimming the edges wherever possible and appropriate as well as mosaicing the sidescan traces together to obtain a map as complete as possible with a resolution of 2 m bins (i.e. 1 pixel equals 2 m of seafloor). Paper print-outs and a GeoTiff were delivered. This data was then also imported into the ArcView GIS, and again the GIS was used as the medium of display and ongoing data analysis and interpretation.

2.2 Drop-down camera survey methodology

2.2.1 Drop-down camera system

The camera equipment used during the survey was a Kongsberg Simrad OE14-208 Digital Stills Camera System mounted obliquely on a seabed camera frame (figure 6). A flash unit and two sub-sea lights were also mounted on the frame. These units were linked to the surface with a soft umbilical cable. All controls of the camera system were kept in the wheelhouse of the survey vessel.

Figure 6. Camera system mounted on a similar seabed frame to that used during the Lamlash Bay survey (red rectangle: camera; yellow rectangle: flashgun and green rectangle: sub-sea light).

The camera system sent a continuous, real-time, analogue video feed to the surface, where the deployment was monitored and the camera / winch were controlled. The analogue video feed was recorded digitally using Mini Digital Video (miniDV) tapes and backed-up using super VHS tapes. The video was recorded to tape rather than DVD as the quality and life expectancy of tape is much greater. Individual still photographs were taken using a surface controlled trigger.

2.2.2 Camera operation and deployment

The drop-down camera survey was carried out between 16th and 20th October 2008. The camera system was only deployed in suitable weather conditions by a team of experienced personnel. Before each deployment a ‘clapper board’ containing site name, date and weather conditions was videoed and photographed as a quality assurance (QA) record.

All camera deployments were established as transects across sites of interest, which were selected after scrutinising the acoustic survey data (figure 7). The vessel was positioned at one end of a transect using DGPS. The camera was then deployed and lowered to the seabed. Once the camera system was at the seabed and had time to settle, the onboard surveyors started to log navigation and the skipper was given approval to start drifting along the transect at about 0.5 knots.

Figure 7. Drop-down camera sampling locations (tracks) for the Lamlash Bay habitat mapping survey 2008.

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

During the deployment, the control of the camera and winch were solely with the camera operator. The winch was controlled using a remote control, whilst photographs were taken using a surface trigger in the wheel house. Photographs were taken regularly along the transects at the discretion of the camera operator to capture the general seabed environment and the fauna present with an additional aim being to ensure that any changes in the seabed environment were recorded.

Throughout each camera deployment, navigation data was recorded. All camera deployment log keeping was synchronised to the navigation data using the time from the RTK GPS. The log keeper recorded the time from the GPS at the start and end of each deployment and the time each photograph was taken. After each deployment the camera was removed from the frame and secured in the wheel house. The digital photographs were then uploaded from the camera to a laptop computer via a USB lead (the software used for this was Canon Zoom Browser EX). During the upload process each photograph was named with the site-name and photograph number.

2.2.3 Data handling

The photographs and video footage were then used for analysis in the GIS. When the camera survey was completed the miniDV tapes were taken back to Seastar Survey Ltd. offices by a member of staff and the backup VHS tapes were transported to an offsite data storage facility. After the survey the digital miniDV tapes were up-loaded to a computer, edited, titled and burnt to DVD as mpeg files. All DVDs, photographs and logs were checked for errors as part of Seastar Survey Ltd’s standard quality control procedures and all data supplied to the client. Finally the client was supplied with DVDs with mpeg video files, sets of all seabed photographs and the seabed photographs were also incorporated into the ArcView GIS.

2.3 Video and photographic analysis

2.3.1 Analysis of the photographs and video records

The analysis of the photographs and video records was carried out ‘blind’, without any prior knowledge of the sites, using a personal computer and a SONY digital videocassette recorder and a television monitor respectively. The latter system allows slow-motion, freeze- frame and standard play analysis. An initial assessment of a site was carried out by first looking through the photographs and film from the particular site quickly to get a brief understanding of the substratum, flora and fauna.

2.3.1.1 Semi-quantitative analysis of the video footage

The video analysis included an initial assessment of a deployment to get a broad understanding of the substratum, flora and fauna as well as the identification of the different biotopes/habitats on the seabed. The positions of the boundaries of the different biotopes/habitats were determined using the time codes and related back to the navigation data

The detailed analysis consisted of a general seabed description and the fauna were identified to the lowest practical level. General descriptions of the faunal life-forms were made and any other features of interest such as trawl marks were also recorded.

The abundance data were recorded using the SACFOR scale (mainly) with the analysis concentrating on the commercially important species present together with species readily identified in the video material. A list of the encountered fauna were produced for each site using species reference numbers as cited in the Marine Conservation Society Species Directory (Howson and Picton 1997) to avoid problems in species nomenclature. The sections or deployments were subsequently classified into designated biotopes according to Connor et al. (2004). Faunal densities were calculated based on the distance covered for each habitat, biotope or transect, basing the calculations on the estimated assumption that

the camera covers 1 m in width (previous camera calibration test gives a seafloor coverage of approximately 0.8 m by 0.8 m when the camera frame is in contact with the seabed). The distances for each habitat have been calculated from the position of the start of each habitat / biotope to the position of the end of each habitat / biotope rather than attempting to calculate the exact distance along the transect (as this proved too complicated) resulting in approximate density values.

2.3.1.2 Quantitative analysis of the stills photographs

The still photography analysis was carried out using a personal computer. The methodology is in large parts similar to the video analysis methodology described for the video analysis and included a general seabed description where the substrata were described according to the Wentworth scale (see Leeder, 1982) with boulders and cobbles being described within ‘gravel’ and rock referring to bedrock. The fauna was identified to the lowest practical level with the nomenclature according to the Marine Conservation Society Species Directory (Howson and Picton 1997) and actual abundance of the fauna and flora was recorded whenever possible (faunal densities are based on the approximation that each photograph covers 1 m2; see camera calibration notes above). The presence of faunal life-forms and any other features of interest such as trawl marks were also recorded. Each photograph was subsequently classified into designated biotopes according to Connor et al. (2004), wherever possible. These results were subsequently incorporated into the ArcView GIS.).

2.4 Sediment sampling

Sediment samples were taken using a 0.1 m2 Day grab. Grab samples were taken at 10 locations across the NTZ (figure 8). The grab sites were selected to represent the different sediment types indicated by the sidescan sonar data and seabed video footage. Prior to deployment the grab was cleaned out using the vessels seawater deck wash to remove any remaining sediment or contamination. The Day grab was then deployed by the vessel’s crew from the crane on the port side of the vessel. The grab was lowered to the seabed until the cable went slack indicating that the grab had reached the seabed. The grab was then recovered to deck where the sample was inspected by the environmental scientist. Grab samples were rejected on the grounds of poor quality for the following reasons:

 Uneven surface indicative of striking the seabed at an angle  Washed out sample  Disturbed surface sediment  Contamination of the sediment (e.g. hagfish, paint chips, oil)  Sample touching the top of the grab  Sample <40% of the grab’s capacity

If the grab sample was acceptable a photograph was taken with a sample label in the image indicating the sampling area and drop number. A small sub sample (approximately 100g) was taken from each of the grab samples for particle size analysis (PSA). The contents of the grab were then washed into a collecting tray under the grab stand. The sediment was gently washed over a 1 mm sieve. The material retained on the sieve was then transferred into a 5 dm3 (litres) plastic bucket and fixed using a 4 % buffered formaldehyde solution to prevent sample degradation.

Figure 8. Sediment sampling locations for the Lamlash Bay habitat mapping survey 2008.

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

The processing of the macrofaunal sediment samples took place at Seastar Survey’s laboratory in Southampton. The sediment samples were gently re-sieved on 1 mm sieves and sorted (using trays and low-magnification microscopes). The fauna was subsequently identified to the lowest practical level (species in most cases) with reference to the species directory (Howson and Picton, 1997) to avoid problems with nomenclature. A full list of taxa encountered and abundances per sample are recorded on a standard species / sample matrix (appendix 06) A reference collection was created and a Quality Control (QC) exercise was also carried out by Artoo Marine Ecological Consultants to check the identification results.

The invertebrate specimens collected were separated by species and by station, preserved in alcohol, and stored in glass sample vials with polyethylene closures to facilitate their incorporation into the collections of The National Museum of Scotland.

The particle size analysis also took place in Seastar Survey’s laboratory following standard protocols using a combination of wet and dry sieving techniques at 1 phi intervals. The PSA followed the sediment grades used by the MNCR (Marine Nature Conservation Review) as described below:

Pebble – medium (> 8 mm) Pebble – small (4-8 mm) Granule (2-4 mm) Sand very coarse (1000-2000 m) Sand coarse (500-1000 m) Sand medium (250-500 m) Sand fine (125-250 m) Sand very fine (63-125 m) Silt and clay (mud) (<63 m)

The dry weight of the whole sediment sample was determined and any muddy samples were disaggregated using a suitable method (e.g. sodium hexametaphosphate). The sample was wet sieved on a 63 m mesh then dried and re-weighed to establish the weight percentage of the sub 63 m fraction. The remainder of the sample was dry sieved with an appropriate sequence of mesh sizes to yield weight percentage data for particle size fractions at half phi intervals. This was done from a minimum sieve size of 63 m to a maximum sieve size of 16 mm.

2.5 Data analysis

Ecological interpretation of the results has been carried out by reference to the JNCC Marine Nature Conservation Review Biotope Classification (Connor et al., 2004), and the presence of rare or unusual species identified against the list in Sanderson (1996). All the identified and enumerated benthic macrofauna were used in the analysis and the abundance data are given in the SACFOR scale (see Connor et al., 2004) for the video records and actual abundance, given as number of individuals/m2, for the still photographs. The macrofaunal sediment data are given in number of individuals/0.1 m2.

The data analyses comprised both univariate and multivariate analyses all of which were calculated using Primer (Plymouth Routines in Multivariate Ecological Research) v 5.2.0 (Clarke and Warwick, 1994). The univariate analysis included the total number of individuals (N), total number of species (S), species diversity where the Shannon-Wiener (H’), Pielou’s (J) and Margalef’s (d) diversity indices (see e.g. Gage and Tyler, 1991; Fowler and Cohen, 1992; Clarke and Warwick, 1994) were used with the natural log (loge) being the chosen parameter in the case of the Shannon-Wiener diversity index. The multivariate analysis was carried out using cluster analysis and ordination (non-metric multi-dimensional scaling, MDS). These data were then transformed to square root to down-weigh the importance of common types of macrofauna in relation to rarer types. The transformed data were then analysed using the Bray-Curtis similarity coefficient (using Primer v.5) followed by a cluster analysis where the sites were group averaged and the resultant dendrogram plotted. Non-metric multi-dimensional scaling (MDS) was then carried out to further assess the presence of any similarities between sites (Clarke and Warwick, 1994). Spearman’s rank correlation coefficient (see e.g. Fowler and Cohen, 1992) was then used to assess any correlations with the particle size analysis variables. The BIOENV routine in PRIMER was used to carry out this task on untransformed abiotic data. The SIMPER routine in PRIMER was subsequently used to assess the difference in characteristic species/ taxa in the samples.

2.6 Survey limitations

2.6.1 Survey vessel

The main factor limiting the Lamlash Bay survey was the use of the vessel Alba na Mara as the draught of the vessel (5.25 m with the transducer pole down) prevented any survey operations shallower than the 10 m contour. This excluded a large section of Lamlash Bay area from the survey including some areas in the north of the No Take Zone believed to be dominated by rocky ‘reef’ habitats (as defined in the European Habitats Directive 92/43/EEC). This issue was raised during the survey operations but after consultation SNH decided to complete the current stage of the survey using Alba na Mara.

2.6.2 Obstructions

As a result of a line of fishing pots, a large section in the centre of the Lamlash Outer (the survey area outside Lamlash Bay) was prevented from being surveyed. In addition, a section in the south-west was also excluded from the survey as a result of the presence of fish farm cages.

3 RESULTS

3.1 Acoustic analysis

The processing and analysis of the acoustic data (bathymetric data and sidescan sonar mosaic) from the acoustic survey (410 kHz sidescan sonar and 38 kHz single beam echo sounder) revealed areas of different levels of backscatter, suggesting clear changes in bathymetry, sediment type and or sediment composition within the survey area (see figures 5 and 8). These patterns and features were used to direct the selection of deployment locations for the underwater video (see figure 7) and still camera system as well as the sediment grab sampling (see figure 5).

The analysis of the sidescan sonar mosaic reveals a number of areas with a low backscatter return, particularly in the inner, deeper parts of Lamlash Bay (central and southern sections) whilst high backscatter returns are found in shallower water, particularly around the northern and southern sections of the North Channel, a number of small areas northwest of Holy Island and along the coast in Outer Lamlash area (see figures 5, 8 and 9). To illustrate some of these features, both natural and anthropogenic, a number of targets (sections of the sidescan sonar mosaic) have been selected and the positions of the features are given in figure 9 (NB. the sidescan sonar images are displayed using inverted grey scale, therefore shadows appear black).

Figure 9. Sidescan sonar image with selected targets to illustrate some of the features identified in Lamlash Bay.

Based upon Ordnance Survey material with the permission of the Controller of HMSO © Crown Copyright (2009) Licence no. 100017908

3.1.1 Target 1 - anchor sinkers

These anchor sinkers (figure 10) features are situated at the south of Lamlash Bay, adjacent to a fish farm and illustrates two anchor sinkers (approximately 1 m x 2 m in dimension) with multiple chains. The distance between the two sinkers is approximately 14 m. This is a good example of the detail and clarity of the data obtained by the sidescan sonar and illustrates one of the human activities / impacts in the bay.

Figure 10. Anchor sinkers seen in the southern section of Lamlash Bay (located approximately at East (X): 204779.6 and North (Y): 629190.2).

3.1.2 Target 2 - anchor drag marks

Anchor drag marks with sediment build up are present in the central and southern sections of Lamlash Bay (figure 11). This image is approximately 50 m wide with the anchor drag marks being approximately 58 m long. There are several of these drag marks across this section of the bay, some of which are over 200 m long.

Figure 11. Anchor drag marks in the southern section of Lamlash Bay (located approximately at East (X): 204804.31 and North (Y): 629718.87).

3.1.3 Target 3 - scallop dredge marks

There is some evidence of fishing activity along the west coast of Holy Island, in this case scallop dredging activity, with the dredge marks (individual tracks are approximately 5 m wide) creating a circular pattern centred around a small mound (figure 12) just outside the survey area. The conical shapes of the positive targets also visible on the sidescan image are possibly a result of deposition of sediment material from the dredges.

These features were detected at the outer limit of the sidescan sonar trace (as a result of the relatively large draught of the survey vessel) and further sidescan sonar coverage in the shallow water along the Holy Island west coast is required to assess the full extent of this activity.

Figure 12. Scallop dredge marks in the southern section of Lamlash Bay (circular pattern centred on East (X): 205270.52 and North (Y): 629791.71).

3.1.4 Target 4 - exposed bedrock

Target 4 is from North Channel and it consists of an area of high backscatter return with relief, surrounded by a low backscatter. This target has been interpreted as exposed bedrock and boulders surrounded by coarse (boulder, cobble and gravel debris) and soft sediment (sand) types (figure 13). The bedrock target is approximately 24 m long, 12 m wide and 1.8 m high.

Figure 13. Exposed bedrock near the shallow sill in North Channel in Lamlash Bay (located approximately at East (X): 206105.47 and North (Y): 632224.95).

3.1.5 Target 5 - Deacon Rock

Target 5 (figure 14) is a section (image width is approximately 100 m) of Deacon Rock with a mottled appearance of high and low backscatter with some relief discernable in the high backscatter returns. This seabed environment has been interpreted to consist of boulders (largest being approximately 0.8 m in height), cobbles and other coarse sediment types surrounded by sediments returning low backscatter, suggesting the presence of sand. Figure 14. Deacon Rock in Lamlash Bay (located at East (X): 204509.00 and North (Y): 630898.00).

3.1.6 Target 6 - sediment furrows

Target 6 is from an area of sediment giving low backscatter returns, sediment interpreted as sand; with a additional feature illustrating (figure 15) several sediment furrows is illustrated (the approximate image dimensions are: 80 m in length and 60 m in width). The origin of these furrows is unknown.

Figure 15. Sediment furrows in the centre of Lamlash Bay (located at East (X): 204081.00 and North (Y): 630704.00).

3.1.7 Target 7 - low backscatter return (sand)

The most predominant seabed sediment feature across Lamlash Bay is illustrated in figure 16 (the image is approximately 50 m wide). This low backscatter return is interpreted as muddy sand and a feature present throughout the central and southern sections of Lamlash Bay. These areas are interspersed with areas of coarser sediment (including gravel) and shell debris.

Figure 16. An area of low backscatter return in the south of Lamlash Bay (located at East (X): 205989.00 and North (Y): 628454.00).

3.1.8 Target 8 - mottled high and low backscatter

Areas of mottled high and low backscatter are interpreted as gravel interspersed with sand. It is a seabed environment found across Lamlash Bay and in central and northern sections in particular; appearing as mottled high and low backscatter returns (figure 17). The image is approximately 50 m wide and the largest boulder is about 1 m in height (1.5 m wide and 2.5 m long).

Figure 17. An area of high mottled backscatter return in the south of Lamlash Bay (located at East (X): 205110.26 and North (Y): 628864.17).

3.1.9 Target 9 - mottled high and low backscatter

In some of the shallower areas of Lamlash Bay, such as the central region at Deacon Rock and southern and northern boundaries of North Channel, the seabed comprised areas of coarse sediment. This mottled high back scatter return with relief is interpreted as cobbles and small and large boulders, surrounded by sediments returning low backscatter, suggesting the presence of sand (figure 18). The images are approximately 100 m wide.

Figure 18. An area of high, low and mottled backscatter illustrating cobbles, boulders and rocks surrounded by sand (located at East (X): 204182.71 and North (Y): 630457.02).

3.1.10 Target 10 - area of seabed with Maerl

The strong returns and mottled appearance are indicative of very coarse sediment (figure 19). Maerl was found to be present at shallower regions, in particular to the north of Lamlash Bay (North Channel) where coarse sediment is present. The image (figure 19) is approximately 50 m across.

Figure 19. An area of mottled backscatter to the North West of Lamlash Bay where maerl is present (located at East (X): 204581.00 and North (Y): 631678.00).

3.2 Photographic and video analysis – ground-truthing

3.2.1 Ground-truthing of the sidescan sonar imagery

A total of 19 miniDV tapes with approximately 11 hours of video footage were recorded during the drop-down camera survey and a total of 848 seabed still photographs (869 with clapper boards to identify each deployment) were taken at 22 different locations (table 3 and figure 7).

Table 3. Summary of video and still photography data collected during the 2008 Lamlash Bay surveys.

Location Depth (m) Video duration Number of still (miniDV) recorded photographs LNC01 30.0 00:22:05 18 LNC02 15.3 00:24:28 27 LNC03 11.3 00:31:18 35 LNC04 24.1 00:30:03 50 LNC05 25.4 00:48:38 54 LNC07 20.9 00:49:02 37 LNC08 27.6 00:31:09 69 LNC09 16.1 00:24:56 21 LNC10 29.4 00:37:22 26 LNC11 14.2 00:40:51 23 LNC12 25.6 00:31:46 58 LSC01 40.1 00:35:05 61 LSC02 32.3 00:39:17 48 LSC03 33.2 00:33:47 37 LSC04 39.4 00:44:18 51 LSC05 38.9 00:20:35 19 LSC06 37.6 00:14:28 31 LSC07 34.1 00:31:05 47 LOC01 30.3 00:45:43 79 LOC02 22.8 00:14:16 19 LOC03 - 00:15:26 34 LOC04 20.2 00:09:13 25 TOTAL 11:14:51 869

The selection of sidescan sonar targets (section 3.1) for illustration purposes was carried out subsequent to processing and analysis of the sidescan sonar data. The selection of ground- truthing using the camera was, however, carried out in the field prior to any detailed analysis of the sidescan sonar data. The selected targets in section 3.1 did therefore not always correspond directly to these targets as some features were not obvious on initial interpretation or there simply were too many targets to allow ground-truthing of all of them within the allocated survey period. However, the quality of the sidescan sonar images at most of these targets is sufficient to verify the identity of the features seen.

3.2.1.1 Target 5 - Deacon Rock

The photographic transect (LNC07) near Deacon Rock allows ground-truthing of target 5 (see figure 20) confirming the initial interpretation of a seabed environment with boulders and

cobbles surrounded by sand. The species found on Deacon Rock include Ascidiacea, Antedon bifida, Ophiura sp., Munida rugosa, hydroids and various tubiculous and burrowing polychaetes.

Figure 20. Ground-truthing of target 5 - Deacon Rock (photographs LNC07_26 and 32).

3.2.1.2 Target 7 - low backscatter return

Target 7 has been interpreted as sand and it is a widespread feature across the entire Lamlash Bay survey area. The ground-truthing photographs (example given in figure 21) verify the initial interpretation and illustrate sandy mud and fauna including Ophiura sp, Turritella communis, gobies and burrowing polychaetes.

Figure 21. Ground-truthing of target 7 - low backscatter return (photograph LSC03_0020).

3.2.1.3 Target 8 - mottled high and low backscatter

The mottled high and low backscatter seen in target 8 has been interpreted as gravel, an interpretation confirmed in the photographs, exemplified by the photographs in figure 22. The fauna found in these areas include Cerianthus lloydii, various burrowing and tubiculous polychaetes, Turritella communis, Ascidiacea and the occasional Echinus esculentus and Liocarcinus puber.

Figure 22. Ground-truthing of target 8 (photographs LNC05_48 and LSC04_49).

3.2.1.4 Target 9 - mottled high and low backscatter

The interpretation of target 9 (mottled high back scatter return with relief surrounded by low backscatter) was interpreted as cobbles and small and large boulders, surrounded by sand, features confirmed in the ground-truthing as given in figure 23. Fauna such as brittlestar and maerl beds are found on similar substrata (see examples in figure 23) together with hydroids, polychaetes, scallops, Liocarcinus spp. and Turritella communis as well as some red algae.

Figure 23. Ground-truthing of target 9 (photographs LNC10_21 and LNC08_20).

3.2.1.5 Target 10 - area of seabed with maerl

The ground-truthing of target 10 confirms the initial interpretation of a seabed with strong backscatter returns and mottled appearance to be very coarse sediment (figure 24). Maerl was found at this location, a feature not visible on the sidescan sonar, but this type of seabed environment was shown to be relatively common in the northern and Outer Lamlash regions. Fauna associated with this habitat included hydroids, Cerianthus lloydii and polychaetes as well as some Liocarcinus spp. and scallops.

Figure 24. Ground-truthing of target 10 (photograph LNC11_10).

3.2.2 General descriptions of the biological communities in Lamlash Bay

The analysis of the sidescan sonar mosaic, together with the ground-truthing using the photography and video (data held by SNH) records, allowed for a detailed assessment of the habitats in Lamlash Bay. The interpretation of the mosaic and the ground-truthing revealed a number of features: 1) soft sediments dominated by muddy sand in central and southern regions of Lamlash Bay; 2) a mixture of sediment environments (muddy sand and mixed sediments) in the northern Lamlash Bay and Outer Lamlash Bay area with sections of rocks and brittlestar beds; 3) relatively small rocky reefs (including Deacon Rock); and 4) shallower areas / banks in northern Lamlash Bay, North Channel and Outer Lamlash Bay with maerl beds.

The majority of the photographic / video transects cross a substratum boundary in an attempt to ground-truth more than one type of backscatter return in each deployment in order to increase sampling efficiency. This resulted in more than one habitat as well as different taxa present within each transect, making the descriptive tasks more complicated (see tables 4, 5 and 6).

3.2.2.1 Central and southern Lamlash bay

The central and southern regions of Lamlash Bay are characterised by soft sediment, mainly muddy sand, and the dominant fauna include Amphiura sp., Ophiura sp., Turritella communis and polychaetes (table 4 and figure 25). However, the seabed is not uniformly muddy sand and there are several photographic transects that cross several (minor) boundaries both in terms of the substratum and fauna present. Transect LSC02 illustrate this point perfectly with the first section being dominated by Amphiura sp.; the second section being dominated by Ophiura sp. and Turritella communis; and the third section being dominated by Turritella communis. The sediment appears to be the same in the first two sections but changes to a mixed type (muddy sand and gravel) in the third section.

A total number of 4 biotopes have been recognised for this region of the survey area. The dominant types are SS.SSa.CMuSa.(AbraAirr), exemplified by photograph LSC01 (in figure 25) and SS.SMu.CSaMu.(AfilMysAnit), exemplified by photograph LSC02 (in figure 25). Both of these biotopes have been somewhat tentatively selected (hence the brackets) in the photographic analysis. The latter of the two has been selected rather than SS.SSa.CMuSa.AalbNuc (see Day grab samples below) as Turritella communis is common on the photographs at AfilMysAnit locations but it is not a taxa recorded in AalbNuc. These

two biotopes appear to be very closely linked and grade into each other (Connor et al., 2004). The biotopes resulting from the Day grab and photographic survey may therefore be: 1) a combination of the two; 2) different patches of the two biotopes in the same region or; 3) that these bitopes are based on epifaunal and infaunal data respectively (perhaps more work is needed to decide the composition with more certainty).

The difference between AbraAirr and AalbNuc is subtle but obvious on the photographs in the large number of Amphiura sp. present in the former. Furthermore, the sediment is slightly sandier in AbraAirr compared to AalbNuc.

Table 4. Summary of the video and photographic analyses with the main substrata, fauna and biotope in central and southern Lamlash Bay.

Location Main substrata Main fauna Biotope(s) LSC01 Muddy sand with Amphiura sp. SS.SSa.CMuSa.(AbraAirr) shell Polychaetes SS.SMx.CMx CR.LCR.BrAs.AmenCio.Bri LSC02 Muddy sand with Amphiura sp. SS.SSa.CMuSa.(AbraAirr) shell Ophiura sp. SS.SMu.CSaMu.(AfilMysAnit) Turritella communis SS.SMx.CMx Polychaetes LSC03 Muddy sand Ophiura sp. SS.SSa.CMuSa.(AbraAirr) Turritella communis SS.SMu.CSaMu.(AfilMysAnit) Polychaetes LSC04 Muddy sand with Amphiura sp. SS.SSa.CMuSa.(AbraAirr) shell Polychaetes SS.SMx.CMx CR.LCR.BrAs.AmenCio LSC05 Muddy sand Amphiura sp. SS.SSa.CMuSa.(AbraAirr) Polychaetes LSC06 Muddy sand Amphiura sp. SS.SSa.CMuSa.(AbraAirr) Polychaetes LSC07 Muddy sand Ophiura sp. SS.SMu.CSaMu.(AfilMysAnit) Turritella communis CR.LCR.BrAs.AmenCio Polychaetes

Figure 25. Photographs from the southern and central regions of Lamlash Bay (LSC01_07, LSC02_29, LSC06_26 and LSC07_39).

3.2.2.2 Northern Lamlash Bay and North Channel

The northern Lamlash Bay and North Channel area consists of a very mixed seabed environment with substrata ranging from muddy sand to bedrock (table 5 and figure 26). The fauna is also different in different part of the area including Turritella communis, Munida rugosa, Cerianthus lloydii, polychaetes, ascidians and maerl (table 5 and figure 26).

A total of 5 biotopes have been designated for this area. The dominant biotopes are SS.SMu.CSaMu.(AfilMysAnit) and SS.SMx.CMx.ClloMx(Nem) but the maerl biotope appears to be common in the shallower regions of the survey area and may extend further into the infralittoral region. The circalittoral rock biotope CR.LCR.BrAs.AmenCio (exemplified by LNC10_06 and LNC11_20 in figure 26) has been selected rather than CR.LCR.BrAs.AntAsH as the latter is found in the most sheltered positions in sea lochs, in weak to very weak tidal currents and the fauna is slightly different to the AmenCio biotope. SS.SMu.CSaMu.(AfilMysAnit), exemplified by LNC05, LNC07 and LNC12in figure 26, has been selected in the photographic analysis rather than SS.SSa.CMuSa.AalbNuc (see Day grab samples below) as Turritella communis is common on the photographs but it is not a taxa recorded in AalbNuc. These two biotopes appear to be very closely linked and grade into each other (Connor et al., 2004). The biotopes found here may therefore be: 1) a combination of the two; 2) different patches of the two biotopes in the same region or; 3) that these biotopes are based on epifaunal and infaunal data respectively. The designation of biotopes during the video analysis allowed designation only in lower levels in the hierarchy as less detail is visible in the videos compared to the still photographs (and zooming in on particular fauna and objects is possible).

Location Main substrata Main fauna Biotope(s) LNC02 Muddy sand and Maerl SS.SMPMrl gravel with shell Polychaetes material Cerianthus lloydii Ascidiacea LNC03 Muddy sand and Maerl SS.SMPMrl gravel with shell Polychaetes SS.SMu.CSaMu.(AfilMysAnit) material Cerianthus lloydii Ascidiacea LNC04 Muddy sand and Turritella communis SS.SMu.CSaMu.(AfilMysAnit) mixed sediments Polychaetes SS.SMx.CMx.ClloMx(Nem) LNC05 Muddy sand and Turritella communis SS.SMu.CSaMu.(AfilMysAnit) mixed sediments Polychaetes SS.SMx.CMx.ClloMx(Nem) CR.LCR.BrAs.AmenCio LNC07 Muddy sand and Turritella communis SS.SMu.CSaMu.(AfilMysAnit) mixed sediments Polychaetes SS.SMx.CMx.ClloMx(Nem) with rocks Ophiura sp. CR.LCR.BrAs.AmenCio LNC08 Muddy sand and Ophiura sp. SS.SMu.CSaMu.(AfilMysAnit) mixed sediments Ophiocomina nigra SS.SMx.CMx.ClloMx(Nem) with rocks Ascidiacea CR.LCR.BrAs.AmenCio Turritella communis CR.LCR.BrAs.AmenCio.Bri Polychaetes LNC09 Muddy sandy Maerl SS.SMPMrl gravel with shell Polychaetes SS.SMu.CSaMu.(AfilMysAnit) material Cerianthus lloydii CR.LCR.BrAs.AmenCio Turritella communis LNC10 Mixed sediments Turritella communis SS.SMx.CMx.ClloMx(Nem) Munida rugosa SS.SMu.CSaMu.(AfilMysAnit) Polychaetes CR.LCR.BrAs.AmenCio CR.LCR.BrAs.AmenCio.Bri LNC11 Mixed sediments Maerl SS.SMPMrl Polychaetes SS.SMu.CSaMu.(AfilMysAnit) Turritella communis SS.SMx.CMx.ClloMx(Nem) Ascidiacea CR.LCR.BrAs.AmenCio LNC12 Muddy sand and Polychaetes SS.SMu.CSaMu.(AfilMysAnit) mixed sediment Turritella communis SS.SMx.CMx.ClloMx(Nem) Ophiura sp.

Figure 26. Photographs from the northern Lamlash Bay and North Channel areas of Lamlash Bay (LNC03_09, LNC05_04, LNC07_35, LNC10_02, LNC10_06, LNC11_06, LNC11_20, LNC12_03).

3.2.2.3 Outer Lamlash Bay The Outer Lamlash Bay area consists of a very mixed seabed environment with sections of muddy sand and other sections of mixed and coarse (with gravel, cobbles and boulders) substrata (see table 6 and figure 27). Two transects (LNC01* and LOC02) are dominated by muddy sand and taxa dominated by Turritella communis, Munida rugosa and polychaetes. The other three transects are characterised by a mixed sediment (muddy sand and gravel with rocks in some areas) and with a varied faunal composition (maerl, featherstars, Turritella communis, Ophiocomina nigra, Cerianthus lloydii and polychaetes).

A total of 5 different biotopes have been designated in the Outer Lamlash Bay region (see comments about the selection of the various biotopes above). Photographic examples of the biotopes are given as follows: LOC03 exemplifies the SS.SMx.CMx biotope complex, photograph LNC01_56 exemplifies the CR.LCR.BrAs.AmenCio.Bri (see further examples below) sub-biotope and photograph LNC03_04 exemplifies the SS.SMx.CMx.ClloMx(Nem) biotope (all given in figure 27).

The seabed environment appears to be very mixed in this region and none of the biotopes seems to be particularly dominant relative to others. Maerl is present, particularly on the shallower banks, but there is a big difference in the quality of the maerl with the maerl at LOC01 being relatively healthy whilst the maerl at LOC04 is difficult to detect at all.

Table 6. Summary of the video and photographic analyses with the main substrata, fauna and biotopes (mixed sediments are muddy, gravelly sands with shell material) in Outer Lamlash Bay (* LNC01 has been placed with Outer Lamlash Bay in the general description stage).

Location Main substrata Main fauna Biotope(s) *LNC01 Muddy sand Turritella communis SS.SMu.CSaMu.(AfilMysAnit) Munida rugosa Polychaetes LOC01 Mixed sediments Maerl SS.SMPMrl Turritella communis SS.SMu.CSaMu.(AfilMysAnit) Antedon bifida SS.SMx.CMx.ClloMx(Nem) CR.LCR.BrAs.AmenCio LOC02 Muddy sand Turritella communis SS.SMu.CSaMu.(AfilMysAnit) Polychaetes LOC03 Muddy sand and Maerl SS.SMPMrl gravel Antedon bifida SS.SMu.CSaMu.(AfilMysAnit) Ophiocomina nigra SS.SMx.CMx Ascidiacea CR.LCR.BrAs.AmenCio Polychaetes CR.LCR.BrAs.AmenCio.Bri LOC04 Muddy sand and Maerl SS.SMPMrl gravel Polychaetes SS.SMu.CSaMu.(AfilMysAnit) Cerianthus lloydii SS.SMx.CMx.ClloMx(Nem)

Figure 27. Photographs from the Outer Lamlash Bay area (LNC01_09, LNC02_17, LOC01_35, LNC01_56, LNC01_71, LNC03_04).

3.2.2.4 Scallops and other noteworthy species

The analysis of the photographic material resulted in identification of scallops (Pecten maximus and Aequipecten opercularis) and a few other noteworthy species (see appendix 07 with a summary in table 7; and figure 28). Munida rugosa is the most abundant taxon in the examples given in table 7 with the highest densities within the CR.LCR.BrAs.AmenCio biotope. Only a few individuals of Cancer pagurus and Nephrops norvegicus were identified in the still photographs whilst Hommarus gammarus was not identified at all.

Scallops were found in all the survey areas in Lamlash Bay (table 7 and appendix 07) with Pecten maximus being the overall most common taxon (in the still photography analysis), with the highest densities found in the SS.SMx.CMx.ClloMx(Nem), SS.SMPMrl and CR.LCR.BrAs.AmenCio biotopes. The highest densities of Aequipecten opercularis were found in the SS.SMx.CMx.ClloMx(Nem) biotope. The densities of Pecten maximus and Aequipecten opercularis appear to be very similar within the NTZ, with densities of both species being around 3 individuals/100 m2.

Table 7. The approximate densities (ind/100 m2) of scallops and two other species present in the still photographs from the 2008 Lamlash Bay survey (total: total number of individuals/100m2; total (N): total number of individuals; NTZ: individuals/100m2 in the NTZ area; LNC: total number of individuals/100m2 in northern Lamlash Bay; LOC: total number of individuals/100m2 in Outer Lamlash Bay; LSC: total number of individuals/100m2 in southern and central Lamlash Bay; Pectinidae sp. are unidentified individuals i.e. not the total of all scallops).

The video analysis rarely allowed identification of the scallop to species level. This group was therefore recorded within the family Pectinidae (table 8). The highest densities of scallops were found in the CR.LCR.BrAs.AmenCio and SS.SMPMrl biotopes with overall densities of scallops being approximately 2 individuals per 100 m2. This is lower than the values seen in the still photography analysis, a result most likely linked to the fact that the identification (observe and count) of fauna is harder on the video compared to the photographs (some scallops were difficult to see even on still photographs; see figure 28). It should be noted that the biotope / habitat designation of individual photographs involves a subjective selection process and it is possible that some of the photographs or areas are classified incorrectly but the densities given in tables 7 and 8 give estimates of the densities of these taxa.

Table 8. The approximate densities (ind/100 m2) of scallops and two other species present in the video footage from the 2008 Lamlash Bay survey (total: total number of individuals/100m2; total (N): total number of individuals; LNC: total number of individuals/100m2 in northern Lamlash Bay; LOC: total number of individuals/100m2 in Outer Lamlash Bay; LSC: total number of individuals/100m2 in southern and central Lamlash Bay; Pectinidae sp. are the total number of scallop individuals as identification of scallops species is difficult on video footage. * MuSa not distinguished during the video analysis hence no data in these fields).

Video footage Pectinidae Cancer Nephrops Pleuronectidae analysis sp. pagurus norvegicus sp. All Total 2.3 0.4 0.1 0.0 Total (N) 342 61 9 2 LNC 2.7 0.3 0.0 0.0 LOC 2.0 0.7 0.2 0.0 LSC 1.9 0.2 0.0 0.0 SaMu Total 2.3 0.5 0.1 0.0 CMx Total 1.8 0.5 0.0 0.0 Mrl Total 2.5 0.1 0.0 0.0 AmenCio Total 4.4 0.1 0.0 0 AmenCio MuSa Total * * * * SaMu SS.SMu.CSaMu.(AfilMysAnit) CMx SS.SMx.CMx.ClloMx(Nem) Mrl SS.SMPMrl AmenCio CR.LCR.BrAs.AmenCio AmenCio CR.LCR.BrAs.AmenCio.Bri MuSa SS.SSa.CMuSa.(AbraAirr)

Figure 28. Examples of scallops observed in Lamlash Bay (LNC08_37, LNC03_31, LNC08_22 and LNC03_18).

3.2.2.5 Maerl beds

As noted above, maerl beds (SS.SMPMrl.Pcal) were identified in the northern Lamlash Bay, in North Channel and in the Outer Lamlash Bay (figure 29). They are typically found in the shallower areas (≤26 m) of the survey area and these beds may extend into the shallower regions immediately outside the boundary of the current study area. The maerl beds are found at LNC02, LNC03, LNC09, LNC11, LOC01, LOC03 and LOC04 (see figure 29) but the vast majority of these beds are in a poor condition. The maerl bed at LOC01 is the healthiest population with the largest proportion (5-10 %) of live maerl. LOC04 is an area with some maerl in particularly poor health with very few scattered individuals present (all dead). In fact, in many cases it was difficult to identify the maerl without zooming in on the images and maerl was not detected during the video analysis, illustrating the need for both still photography and video footage to ensure recording large-scale and small-scale features. LOC04 can therefore not be classified as a maerl bed and this location is best described as an area of scattered maerl.

Figure 29. Maerl beds observed in and around Lamlash Bay (LNC02_04, LNC03_02, LNC0902, LNC11_02, LOC01_03, LOC03_19).

3.2.2.6 Brittlestar beds

Patches of seabed with brittlestars (CR.LCR.BrAs.AmenCio.Bri) were observed at several locations (LNC08, LNC10, LOC03, and LSC01) of the Lamlash Bay survey (figure 30). The dominant taxon was Ophiocomina nigra but the other brittlestar taxon Ophiothrix fragilis often seen together with O. nigra was not seen in these samples.

Figure 30. Brittlestar beds in Lamlash Bay (LNC08_19, LNC08_20, LOC3_ 08 and LSC01_55).

3.3 Sediment samples

A total of 10 Day grab samples were collected within the NTZ in Lamlash Bay (table 9 and appendix 03). A sub-sample was collected for Particle Size Analysis and the remaining sample was retained for further macrofaunal processing and analysis.

Table 9. Day grab sampling locations (navigation data in ddmmss.sss).

Location Date Latitude (N) Longitude (W) Depth (m) NTZ01#01 20/10/2008 553239.274 -50547.237 27.5 NTZ02#02 20/10/2008 553228.927 -50567.708 28.6 NTZ03#01 20/10/2008 553218.679 -50591.838 30.0 NTZ04#01 20/10/2008 553224.860 -50608.735 26.9 NTZ05#01 20/10/2008 553208.646 -50581.213 22.1 NTZ06#03 20/10/2008 553198.133 -50567.949 15.6 NTZ07#01 20/10/2008 553225.128 -50538.758 20.4 NTZ08#02 20/10/2008 553241.085 -50507.473 19.7 NTZ09#01 20/10/2008 553254.641 -50562.384 20.3 NTZ10#01 20/10/2008 553251.697 -50467.579 22.5

3.3.1 Particle Size Analysis

The results from the particle size analysis from the Day grab samples are given in appendix 04 with a summary in table 10 (mud, sand and gravel refer to all size fractions within each category). The results illustrate that all the sites are dominated by “sand” with at least a proportion of mud being present at all the locations. The highest percentage of mud (>10 %) is found at NTZ02, NTZ03 and NTZ04. Gravel is also present but not at all the locations. NTZ08 and NTZ10 have the highest percentage of gravel but smaller percentage is also present at NTZ07 and NTZ09 (table 10).

Overall, however, and the most important aspect of these results is that sand represents more than 80 % of the sediment at all but one of the 10 sites (see table 10). These 9 locations can therefore classified as “Sand” (greater than 80% sand; see appendix 05) according to the modified Folk triangle (Folk, 1954) sediment classification system as adapted by the Joint Nature Conservation Committee (JNCC; see Connor et al., 2004) with NTZ08 also dominated by sand (77 %). In terms of the sediment present, 9 sites could therefore also classify as SS.SSA (sublittoral sediment, sublittoral sands and muddy sands) but as both the sediment type and fauna have to be considered when classifying a site as a particular biotope according to the JNCC Marine Nature Conservation Review Biotope Classification (Connor et al., 2004) system, some of the sites are classified as different biotopes (see below).

Table 10. Summary of the Particle Size Analysis (sediment weight by percentage) from the NTZ in Lamlash Bay.

Depth Gravel Sand Mud Classification Location (m) (%) (%) (%) (Wentworth scale) NTZ01#01 27.5 0.04 94.76 5.44 muddy sand NTZ02#02 28.6 0.03 90.24 10.00 muddy sand NTZ03#01 30.0 0.04 88.85 11.29 muddy sand NTZ04#01 26.9 0.06 87.61 12.10 muddy sand NTZ05#01 22.1 0.27 90.52 9.35 muddy sand NTZ06#03 15.6 0.14 93.78 6.17 muddy sand NTZ07#01 20.4 5.33 88.45 6.36 gravelly muddy Sand NTZ08#02 19.7 15.77 77.20 7.09 muddy gravelly Sand NTZ09#01 20.3 1.49 89.68 8.86 gravelly muddy sand NTZ10#01 22.5 11.93 81.86 6.32 muddy gravelly Sand

The “sand” size class can be further divided according to the sediment size classification based on the Wentworth scale (see e.g. Leeder, 1982). Further analysis of the data shows that within the ‘sand’ category, all the sites are dominated by fine or very fine sand (figure 31 and table 11). Relatively higher proportions of medium and coarse sand, as well as the gravel fractions noted above, are found at three locations (NTZ07, NTZ08 and NTZ10).

Table 11. Total percentage sediment weight (brown: ‘gravel’; yellow: ‘sand’; light yellow: ‘silt’) of the Day grab samples at the NTZ locations in Lamlash Bay (NB. processing differential resulting in total percentage being in excess of / less than 100%).

Sieve NTZ01 NTZ02 NTZ03 NTZ04 NTZ05 NTZ06 NTZ07 NTZ08 NTZ09 NTZ10 size 16.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8.000 0.00 0.00 0.00 0.00 0.20 0.00 0.29 5.13 1.49 4.39 4.000 0.00 0.00 0.02 0.00 0.00 0.00 1.07 3.45 0.00 3.92 2.000 0.04 0.03 0.02 0.06 0.07 0.14 3.97 7.20 0.00 3.63 1.000 0.38 0.18 0.22 0.19 0.57 0.72 9.15 7.36 0.09 4.96 0.500 1.55 0.65 0.75 0.95 1.32 2.31 6.77 5.84 1.28 6.19 0.250 7.08 3.49 3.55 4.28 5.77 9.72 19.06 13.03 7.28 17.79 0.125 53.04 37.14 26.68 16.85 41.50 50.42 42.63 38.11 38.91 39.31 0.063 32.71 48.78 57.66 65.34 41.36 30.62 10.84 12.86 42.12 13.60 < 0.063 5.44 10.00 11.29 12.10 9.35 6.17 6.36 7.09 8.86 6.32

Figure 31. Cumulative percentage sediment weight at the NTZ locations in Lamlash Bay.

3.3.2 Macrofaunal distributions

The macrofaunal analysis revealed a total of 2726 individuals and 160 taxa (appendix 06) in the Lamlash Bay Day grab samples (including meiofauna and epi-fauna). Overall the macrofauna is dominated by Mollusca (45.0%) and Annelida (30.7%), representing 75.7% of the identified fauna. The Echinodermata and Crustacea comprise 16.0% and 6.3% of the macrofauna respectively while the Nemertea represent 1.0% and the remaining groups (Cnidaria, Sipuncula and Ascidiacea) represent 0.08% of the fauna. One individual of Gobiidae sp. was also found in one of the Day grab samples.

3.3.2.1 Abundance

The abundance of the identified macrofauna collected in the NTZ in Lamlash Bay Day grab survey is given in appendix 06 with some examples of the most abundant species / taxa given in table 12. As with the overall data, Mollusca and Annelida dominated the macrofaunal community. The most abundant taxon is Mysella bidentata, followed by Amphiura filiformis, Prionospio fallax and Thyasira flexuosa.

Mysella bidentata is typically found in muddy sand and fine gravel (sometimes in burrows of sipunculids or associated with ophiuroids) while the suspension feeder Amphiura filiformis is found in muddy sand (Hayward and Ryland, 1991). Thyasira flexuosa is typically found in sandy muds (Tebble, 1976). The ecology of the dominant fauna therefore seems to correlate with the dominant sediment types in Lamlash Bay (silty sand) and although little information is available for the ecology of Prionospio fallax, the current data suggest that P. fallax is also found in muddy sand (most abundant in locations with the highest percentage of silty sand: see appendix 06).

Table 12. Total number of individuals of the most abundant taxa/species present in the 2008 Lamlash Bay survey (rank order).

MCS Taxon Species Abundance code W1906 Mysella bidentata 940 ZB154 Amphiura filiformis 370 P765 Prionospio fallax 172 W1837 Thyasira flexuosa 111 P94 Pholoe synophtalmica 66 P1098 Owenia fusiformis 66 W2128 Dosinia lupinus 42 P494 Nephtys spp. 35 P499 Nephtys hombergii 35 P579 Lumbrineris gracilis 30 P919 Mediomastus fragilis 30 ZB121 Ophiuroidea sp. 29 P502 Nephtys kersivalensis 28 P1178 Trichobranchus roseus 28 S440 Ampelisca tenuicornis 28 W1569 Nucula nitidosa 28 P1124 Melinna palmata 25 S440 Tanaopsis graciloides 24 G1 NEMERTEA spp. 23 S248 Urothoe elegans 23 P1139 Ampharete lindstroemi 22 ZB223 Echinocardium cordatum 22

3.3.2.2 Diversity

The results from the species diversity analysis are given in table 13. The total number of individuals present at the 10 Lamlash Bay Day grab samples range from 133 individuals per sample to 474 individuals per sample whilst the total number of taxa range from 37 to 64 among the samples, indicating that there are some differences between the different locations.

The species diversity (Shannon-Wiener diversity index) overall is low (to medium) with diversity being highest at locations NTZ 05 to NTZ 10. The equitability (J) results suggest a similar pattern where locations NTZ 01 to NTZ 04 have low equitability, indicating higher dominance by a small number of different species, while the results from the other locations (NTZ 05 to NTZ 10) indicate a more equal distribution between species.

Location S N d J H' (loge) NTZ 01#01 49 474 7.79 0.51 1.98 NTZ 02#02 53 369 8.80 0.54 2.14 NTZ 03#01 37 425 5.95 0.52 1.87 NTZ 04#01 40 304 6.82 0.63 2.33 NTZ 05#01 63 240 11.31 0.80 3.31 NTZ 06#03 47 183 8.83 0.81 3.12 NTZ 07#01 55 162 10.61 0.91 3.64 NTZ 08#02 64 159 12.43 0.94 3.91 NTZ 09#01 43 267 7.52 0.73 2.73 NTZ 10#01 46 133 9.20 0.87 3.33

3.3.2.3 Macrofaunal composition

The results from the cluster analysis and ordination of all the Lamlash Bay infaunal data are given in figures 32 and 33. The cluster analysis group locations NTZ07, NTZ08 and NTZ10 in one cluster whilst the remaining locations are grouped together in a separate cluster (figure 32), results that appear to closely follow the sediment distributions described above (section 3.3.1) where locations NTZ07, NTZ08 and NTZ10 are found in the slightly coarser sediment while the remaining samples are found in ‘fine’ sediments.

Figure 32. Cluster analysis of the 2008 Lamlash Bay macrofaunal Day grab data.

The ordination analysis support the cluster analysis results (figure 33) grouping NTZ07, NTZ08 and NTZ10 together (coarser sediment group) whilst the remaining seven locations are found in the ‘fine’ sediments. The ordination furthermore reveals a very low level of stress (0.01) giving “an excellent representation with no prospect of misinterpretation” (Clarke and Warwick, 1994). The data were analysed using a number of different variables but the results were unchanged further strengthening the results given here.

Figure 33. Ordination analysis of the 2008 Lamlash Bay macrofaunal Day grab data (all 10 locations).

The ordination results given in figure 33 illustrate the seven ‘fine’ sediment locations grouped very closely together. To assess any potential patterns further a second MDS plot of the remaining seven locations was produced (figure 34). This second ordination analysis largely supports the results in the cluster analysis, grouping NTZ05, NTZ06 and NTZ09 in one group and NTZ01 to NTZ04 together in the other, suggesting some small differences between the two faunal communities. The level of stress of the ordination is slightly higher (0.06) in this analysis but still “corresponds to a good ordination with no real prospect of a misleading interpretation” (Clarke and Warwick, 1994).

Figure 34. Further ordination analysis of the 2008 Lamlash Bay macrofaunal Day grab data (the 7 locations grouped).

To assess these groups further, a SIMPER analysis of the 2008 macrofaunal Day grab samples in Lamlash Bay was carried out to assess the most dominant species in the ‘coarse’ (NTZ07, NTZ08 and NTZ10) and ‘fine’ sediment groups as identified in the cluster and ordination analyses (table 14).

Many of the dominant fauna in the ‘fine’ sediment group are typically found in muddy sands (and sandy muds) typified by Mysella bidentata, Amphiura filiformis and Thyasira flexuosa (see above; Tebble, 1966 and Hayward and Ryland, 1995). The relative contribution of Mysella bidentata to this community is very high compared to any of the other species.

The most characterising fauna in the ‘coarse’ sediment cluster are typically found on substrata of a mixed character, preferences supporting the overall clustering. Dosinia lupinus is a suspension feeder found on sandy mud, sand and shell gravel. Mediomastus fragilis is a sub-surface deposit feeder found on muddy gravel, sandy mud, muddy sand and mud. Lumbrineris gracilis is a predator / omnivore found on gravel / shingle, muddy sand and mud.

Table 14. SIMPER analysis of the 2008 macrofauna in Lamlash Bay.

Site % contribution of characterising species Contribution MCS Taxa/species (%) code ‘Coarse’ 11.09 P579 Lumbrineris gracilis 8.23 P919 Mediomastus fragilis 7.92 W Dosinia lupinus 6.88 P765 Prionospio fallax 5.33 P1098 Owenia fusiformis 4.81 G1 NEMERTEA spp. 4.07 S440 Ampelisca tenuicornis 3.71 P94 Pholoe synophtalmica 3.66 S1142 Tanaopsis graciloides 3.07 W1837 Thyasira flexuosa 3.07 P1139 Ampharete lindstroemi ‘Fine’ 40.13 W1906 Mysella bidentata 17.81 ZB154 Amphiura filiformis 9.94 P765 Prionospio fallax 7.22 W1837 Thyasira flexuosa 2.44 P94 Pholoe synophtalmica 2.04 P499 Nephtys hombergii 1.76 P1098 Owenia fusiformis 1.72 P1124 Melinna palmata 1.54 P494 Nephtys spp. 1.23 W1569 Nucula nitidosa

A second SIMPER analysis was carried out assessing the potential differences between the two groups in the ‘fine’ sediment clusters (‘fine 1’ consists of NTZ01 to NTZ04 while ‘fine 2’ consists of NTZ05, NTZ06 and NTZ09) and although there are differences in the communities (table 15), the main difference seem to be the relative contribution of the taxa present as the four most dominant taxa are present in both groups. The results suggest that the relative importance of the number of individuals of both Mysella bidentata and Amphiura filiformis are the most important differences between the two groups, suggesting that there are subtle differences in the habitats forming these two groups.

Table 15. SIMPER analysis of taxa within the ‘fine’ cluster groups in the 2008 Lamlash Bay survey (‘fine 1’ consists of NTZ01 – NTZ04 while ‘fine 2’ consists of NTZ05, NTZ06 and NTZ09). Site % contribution of characterising species Contribution MCS Taxa/species (%) code ‘Fine 1’ 56.24 W1906 Mysella bidentata 21.15 ZB154 Amphiura filiformis 3.74 W1837 Thyasira flexuosa 3.71 P765 Prionospio fallax 1.62 P94 Pholoe synophtalmica ‘Fine 2’ 19.47 P765 Prionospio fallax 18.83 W1906 Mysella bidentata 13.56 ZB154 Amphiura filiformis 11.19 W1837 Thyasira flexuosa 6.71 P1098 Owenia fusiformis

3.3.3 Comparisons between macrofaunal trends and the sediment data

The sediment variables (sediment retained on the different sieve sizes used) were used to assess any correlations between these data and the cluster analysis results (figure 32) using the Spearman rank correlation coefficient (rs) and the results are given in table 16.

The results show that the highest correlation is found between the faunal distributions and sediment retained on sieve size 1.0 (very coarse sand) with a positive correlation of 0.813 but other correlations are also high with sieve sizes 0.063 (0.777), 0.5 (0.751) and 0.25 (0.612) of particular note (these sieve sizes refer to very fine sand, coarse sand and fine sand respectively). Various combinations of sediment sizes were also tested and the highest correlation was found with a combination of 8.0, 4.0, 1.0 and 0.063 sieve sizes which resulted in a Spearman rank correlation coefficient (rs) of 0.85. Overall therefore the results indicate that the sediment size has a strong positive correlation with the faunal distributions in the Lamlash Bay Day grab samples.

Table 16. Results from the Spearman rank correlation coefficient analysis comparing the faunal data with the sediment data collected at Lamlash Bay 2008.

Variable Spearman Rank correlation (sieve size, mm) 16.00 0 8.0 -0.117 4.0 -0.115 2.0 0.413 1.0 0.813 0.5 0.751 0.25 0.612 0.125 -0.181 0.063 0.777 <0.063 0.102

3.3.4 Biotope classification of the 2008 Lamlash Bay Day grab samples

The combination of the sediment distribution, depth and the macrofauna present has resulted in a biotope classification for the Lamlash Bay Day grab samples (table 17). As noted previously, the dominant sediment type throughout the 10 samples was sand (>80 % in all but one of the samples) suggesting that all the locations should be classified within the ‘main habitat’ SS.SSa (sublittoral sands and muddy sands; see above and Connor et al., 2004).

The sediment samples clustered as ‘fine’ in the cluster and ordination analyses (NTZ01 to NTZ06 and NTZ09) could be (based on the depth and sediment size data) classified as biotope complex SS.SSa.CMuSa (circalittoral muddy sand) as the mud content is >5% at all seven locations (see Connor et al., 2004). The dominant fauna in these seven samples (described above) also support this classification but neither of the two biotopes at level 5 in the hierarchy (SS.SSa.CMuSa.AalbNuc and SS.SSa.CMuSa.AbraAirr) seems to fit the fauna identified in Lamlash Bay perfectly. The strongest agreement between many of the taxa present and those described by Connor et al. (2004) are those in the SS.SSa.CMuSa.AalbNuc biotope. This biotope is therefore tentatively selected as the biotope for the locations in the ‘fine’ sediment cluster group (NTZ01 to NTZ06 and NTZ09).

The samples clustered as ‘coarse’ (NTZ07, NTZ08 and NTZ10) were classified as muddy gravelly sand in the Particle Size Analysis (see PSA section above) and the fauna was dominated by different taxa compared to those seen in the ‘fine’ cluster group. Considering the sediment content and the fauna present, these locations have been designated biotope complex SS.SMx.CMx. A more detailed assessment of the fauna in the ‘coarse’ cluster suggests that these locations could be classified as SS.SMx.CMx.MysThyMx (level 5 of the biotope classification hierarchy). This particular biotope is found in moderately exposed or sheltered areas with common infaunal polychaetes species including Prionospio fallax and Lumbrineris gracilis as well as amphipods such as Ampelisca spp. together with the brittlestar Amphiura filiformis. However, this biotope is characterised by the bivalves Thyasira spp. (often Thyasira flexuosa) and Mysella bidentata, and although these taxa are present in the samples, they are not very common. The classification of the locations NTZ07, NTZ08 and NTZ10 can therefore only tentatively be designated as SS.SMx.CMx.MysThyMx at this stage. It should be noted that maerl (Phymatolithon calcareum), has been recorded (in shallow water) as part of this biotope but at low abundances (Connor et al., 2004), an observation that seems to be valid in the current study (see other sections of this report).

Table 17. Summary of the biotope complexes / biotopes for the 2008 Lamlash Bay Day grab samples.

Locations Biotope complex / biotope Sediment type Dominant fauna

NTZ 01#01 Mysella bidentata NTZ 02#02 Amphiura filiformis NTZ 03#01 Prionospio fallax NTZ 04#01 SS.SSa.CMuSa.(AalbNuc) muddy sand Thyasira flexuosa NTZ 05#01 NTZ 06#03 Pholoe synophtalmica NTZ 09#01 Nephtys hombergii

Lumbrineris gracilis Mediomastus fragilis NTZ 07#01 Dosinia lupinus NTZ 08#02 SS.SMx.CMx.(MysThyMx) muddy gravelly sand NTZ 10#01 Prionospio fallax Owenia fusiformis NEMERTEA spp.

3.4 The seabed environment in Lamlash Bay

The analysis of the sidescan sonar mosaic and bathymetry together with the ground-truthing using the photography and video records as well as the incorporation of these data into the ArcView GIS allowed for a more detailed assessment of the habitats in Lamlash Bay. The interpretation of the sidescan sonar mosaic (figure 5) together with the ground-truthing (see examples of photographs above) reveals a complex, patchy and heterogeneous seabed environment difficult to delineate and summarise in a single image. The results are therefore displayed in four images (figures 35 to 38) with the underlying aim not to overly extrapolate the data sets available.

Figures 35 and 36 illustrate the distribution of biotope complexes and biotopes identified in Lamlash Bay. The maerl biotopes (SS.SMPmrl) are illustrated in red and these are found in Outer Lamlash Bay, in the North Channel and in northern Lamlash Bay with at least two beds within the NTZ. As mentioned above, these beds are believed to extend onto the shallower regions outside the current study area (most of the beds are found on the shallower banks at the edges of the current study area) and it would be of considerable interest to investigate these beds further. Note, however, that one location (LOC04) north of the entrance to North Channel, is described as scattered maerl rather than a mearl bed and it is currently unclear whether the maerl found here is more extensive or not.

The purple polygons can be exemplified by Deacon Rock (figure 35) in the centre of the bay. Some coarse material is found around this outcrop but the substrata change gradually in several directions. The direction of the sidescan sonar survey lines seems to affect the quality of the imagery in this region suggesting a need for careful planning for future sidescan sonar monitoring surveys. Other rocky outcrops (CR.LCR.BsAs.AmenCio) are found in the study area, some of which are found within the brown polygons (in figures 35 and 36), which consist of mixed coarse sediments (SS.SMx.CMx) of muddy, sandy gravel. Most of the rocky outcrops are found in northern Lamlash Bay, but more are likely to be found when further survey coverage is achieved.

The surrounding areas in figures 35 and 36 consist of muddy sand and sandy mud but some of these features need additional ground-truthing to increase the levels of confidence in the data. Some of the data have been extrapolated to create these biotope maps using the confidence model described above.

Figures 37 and 38 illustrate the still photography camera transects across the sidescan sonar imagery with each coloured circle signifying one photograph. The colour of the circles signify a biotope (figure 37) or a substrata type (figure 38) and the changes can be seen along each photographic transect. Overall the correlations between the boundaries of sediment / substrata type and biotope / habitat type are very good throughout the survey area but some of the subtle changes in the faunal distributions are not always apparent in the patterns seen in the substrata. This is best exemplified in the sector in the south-southwest where there is no apparent evidence of faunal change across an area that changes from muddy sand to sandy mud (figures 37 and 38). Additional sediment sampling is required to assess the current infaunal compositions within the bay and allow monitoring of any future potential changes in the infaunal composition in these areas.

Furthermore, areas classified as muddy sand biotopes have in many places been classified as sandy mud in the sediment classification and the other way around. The difference in sandy mud and muddy sand is at times very difficult to discern on seabed photographs and video footage but with the presence of burrows and other features the current classification using the photographs is deemed appropriate. Therefore these discrepancies are more likely linked to the biotope classification system which is based on both epi- and infaunal data potentially explaining some of the discrepancies between the two results.