Marine biological survey to establish the distribution and status of ...

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1 INTRODUCTION 1.1 Background The Scottish Government is committed to maintaining a healthy and biologically diverse marine and coastal environment that continues to provide economic, social and wider benefits to meet the long term needs of people and nature. The Marine (Scotland) Act 2010 and the UK Marine and Coastal Access Act 2009 include new powers and duties to help deliver these aspirations. Future marine nature conservation measures in Scottish waters will be based on a three pillar approach, with action at the wider seas level (e.g. marine planning or sectoral controls); specific species conservation measures (e.g. improved protection for seals), and through site protection measures which will see the identification of new Marine Protected Areas (MPAs). Further details are provided in the Strategy for Marine Nature Conservation in Scotland (Marine Scotland, 2011a). To help target marine nature conservation measures under each of the three pillars, Scottish Natural Heritage (SNH) and the Joint Nature Conservation Committee (JNCC) have generated a focused list of habitats and species of importance - the Priority Marine Features (PMFs) (Howson et al., 2012; and JNCC, 2011). A subset of these biological features, those for which area-based protection measures are an appropriate tool, together with the black guillemot and five large-scale features of functional significance for the overall health and diversity of Scotland’s seas, will drive the selection of Nature Conservation MPAs (MPA search features). Recent research projects have collated available datasets detailing the distribution of the full suite of MPA search features and PMFs to ensure that the best practicable use is made of existing records in the identification of new MPAs. New survey work has also been commissioned to validate their continued presence in certain areas and to underpin the development of formal MPA proposals, established using the science-based Scottish MPA Selection Guidelines (Marine Scotland, 2011b). The discovery in the Sound of Canna in 2009 of a population of the rare fan mussel Atrina fragilis, an MPA search feature, during routine monitoring studies of a dredge spoil ground (Marine Scotland Science, 2009) has served to focus attention on this small area, including the commissioning of new detailed marine biological survey work. The sound separates the islands of Canna and Rum in the Small Isles, an archipelago to the south of Skye. Whilst recognised as of importance for basking shark Cetorhinus maximus (one of several ‘hotspots’ on the west coast of Scotland - Speedie et al., 2009), with dramatic underwater cliffs that are a favourite of recreational divers, the area has until recently attracted relatively little attention from marine biologists. 1.2 Survey objectives The purpose of this study was to undertake a detailed seabed habitat survey within the Sound of Canna (Figure 1), with particular emphasis on the population of fan mussels. The survey programme was designed to generate sufficient information on the distribution, quality and extent of MPA search features present, to enable SNH to undertake a preliminary assessment of the merits of the 2010 survey area against the Scottish MPA Selection Guidelines. 1
Figure 1 The 2010 Sound of Canna survey area © Crown Copyright and database right [2012]. All rights reserved. Ordnance survey License number 100017908. This product has been derived in part from material obtained from the UK Hydrographic Office with the permission of the Controller of Her Majesty's Stationery Office and UK Hydrographic Office (www.ukho.gov.uk). NOT TO BE USED FOR NAVIGATION The work programme encompassed the following six main tasks: 1. Review existing information on sublittoral MPA search features and PMFs within the survey area. 2. Design and undertake a survey programme to ascertain the current distribution, quality and extent of MPA search features and PMFs present within the sound. 3. Determine the extent of the population of Atrina fragilis and define areas of differing density (if applicable). 4. Produce a full coverage predictive habitat map of the area, building upon and refining existing broadscale mapping. 5. Note any human uses of the area. 6. Undertake a preliminary assessment of the merits of the 2010 survey area against a specified subset of the guidelines developed to support the identification of new Nature Conservation MPAs in Scottish waters (Marine Scotland, 2011b). 1.3 Review of existing data 1.3.1 Geology and topography of the area The islands of Canna and Sanday are formed largely of tertiary basaltic lava, which originated from an ancient volcano on the Isle of Skye. The basalt on Canna is exposed in a number of places as dramatic organ pipe pillars. Of particular interest to geologists are great thicknesses of boulder conglomerate, with rounded boulders of over a metre in diameter marking the routes of fast-flowing rivers that cut into the lava fields at the time of the volcanic eruptions. 2
Page 1 and 2: Scottish Natural Heritage Commissio
Page 4 and 5: COMMISSIONED REPORT Summary Marine
Page 6 and 7: Contents Page no. 1 Introduction ..
Page 8 and 9: Page no. Figure 28 Basking shark ho
Page 12 and 13: Rum has a far more complex structur
Page 14 and 15: In 1993 an SNH team conducted remot
Page 16 and 17: Richardson et al. (2004) showed tha
Page 18 and 19: 2 METHODS 2.1 Sampling strategy The
Page 20 and 21: Figure 6 Shallow water video statio
Page 22 and 23: Figure 8 Video stations surveyed in
Page 24 and 25: Each discrete grab sample was empti
Page 26 and 27: Following the survey, the infauna w
Page 28 and 29: Table 2 Biotopes identified in the
Page 30 and 31: Figure 11 2010 survey coverage off
Page 32 and 33: Circalittoral sandy mud (SS.SMu.CSa
Page 34 and 35: Description The distribution of the
Page 36 and 37: Figure 16 Division of the megafauna
Page 38 and 39: Some L. saccharina forest (IR.LIR.K
Page 40 and 41: Rhodophyllis werneri and Scinaia in
Page 42 and 43: Plate 8 A northern sea fan Swiftia
Page 44 and 45: Zostera marina/angustifolia beds on
Page 46 and 47: This is consistent with infaunal co
Page 48 and 49: the fan mussels ranged from an esti
Page 50 and 51: Plate 13 A small basking shark in C
Page 52 and 53: Distribution Depth range: 72 - 21
Page 54 and 55: Figure 31 Other species of interest
Page 56 and 57: coverage predictive biotope distrib
Page 58 and 59: 4 DISCUSSION This section presents
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Table 4 Summary of the assessment o
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The burrowed mud supported langoust
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in areas where it is protected from
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Table 6 Summary of a preliminary as
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5.2 Future data review and biologic
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Ingle, R.W. (1996). Shallow-water c
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Appendix 1 Drop-down video and dive
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Date Station Time Latitude Longitud
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Table A1.2 Summary notes (biologica
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Tow Id no Tow Data point Date Tape
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Tow Id no Tow Data point Date A123
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Table A1.3 Summary of sampling unde
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Site No. Date Habitat Id (Site No:H
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Species MCS Code D D 1 _ 2 D D 1 _
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Species MCS Code Suberites ficus C2
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Species MCS Code Cryptopleura ramos
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Species MCS Code Scrupocellaria Y83
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Table A1.6 Species recorded (matrix
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Species MCS Code A 1 2 _ 1 A 1 2 _
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Table A1.7 Species recorded (matrix
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Species MCS Code Dive 1.1 Dive 2.1
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Table A2.1 Positional and depth inf
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Table A2.3 List of taxa identified
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Taxa MCS Code G 01 G 02 G 03 G 04 G
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Taxa MCS Code G 01 G 02 G 03 Diasty
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Taxa MCS Code G 01 Ascidiella sp. Z
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Figure A2.1 Bray-Curtis similarity
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Appendix 3 Macrofaunal and sediment
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Table A3.3 Results of univariate an
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Appendix 4 Photo and video logs - 2
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File Name Subject Site Name Island
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Table A4.2 Drop-down video log, 201
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File Name File size Folder Site No
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File Name File size Folder Site No
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