The Distribution of Priority Marine Features and MPA Search Features Within the Ullapool Approaches: a Broadscale Validation Survey
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Scottish Natural Heritage Commissioned Report No. 422 The distribution of Priority Marine Features and MPA search features within the Ullapool Approaches: a broadscale validation survey COMMISSIONED REPORT Commissioned Report No. 422 The distribution of Priority Marine Features and MPA search features within the Ullapool Approaches: a broadscale validation survey For further information on this report please contact: Dr Colin Trigg Scottish Natural Heritage Great Glen House INVERNESS IV3 8NW Telephone: 01463-725014 E-mail: [email protected] This report should be quoted as: Moore, C. G., Harries, D. B., Trigg, C., Porter, J. S. and Lyndon, A. R. (2011). The distribution of Priority Marine Features and MPA search features within the Ullapool Approaches: a broadscale validation survey. Scottish Natural Heritage Commissioned Report No. 422. 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. © Scottish Natural Heritage 2011 i COMMISSIONED REPORT Summary The distribution of Priority Marine Features and MPA search features within the Ullapool Approaches: a broadscale validation survey Commissioned Report No. 422 (Project no. 32056, iBids no. 10767) Contractor: Heriot-Watt University Year of publication: 2011 Background The survey area is located in north-west Scotland and extends from the southern entrance of Loch Gairloch to Loch an Alltain Duibh in the north, enclosing a coastal area referred to in this report as the Ullapool Approaches. For the purposes of the current study the area is regarded as consisting of a number of regions, which include the four major loch systems (Loch Gairloch, Loch Ewe, Little Loch Broom and Loch Broom), Gruinard Bay, the Summer Isles, and the Outer Region, which comprises the large embayment between Rubhá Réidh and Loch an Alltain Duibh, and the coastal strip extending southwards from Rubhá Réidh to Loch Gairloch. To help target nature conservation action SNH and JNCC have generated a focused list of habitats and species of importance in Scottish waters - the Priority Marine Features (PMFs). Provisions to designate new Marine Protected Areas (MPAs) within Scottish waters have recently been introduced through the Marine (Scotland) Act 2010 and the UK Marine and Coastal Access Act 2009. A subset of the PMFs (MPA search features) will drive the identification of Nature Conservation MPAs. The purpose of this study was to carry out a validation survey of the multiple PMFs/MPA search features recorded within the Ullapool Approaches, to record new instances of these and to detect previously unrecorded PMFs/MPA search features within the area. For a subset of MPA search features a further objective involved more detailed analysis to determine their distribution, extent and condition. This included maerl, flame shell, seagrass, oyster, blue mussel, horse mussel and sea loch egg wrack beds. A number of sites with geodiversity features were also investigated and their corresponding biological characteristics recorded. Main findings A total of 11 MPA search features were recorded in the survey area in 2010, of which the burrowed mud component biotope SS.SMu.CFiMu.SpnMeg was the most extensive, flooring much of the sea bed in all regions. The associated sea pen, Funiculina quadrangularis, was also widespread, with high population densities present in the inner basins of Loch Broom and Little Loch Broom. However, the burrowed mud habitat in the inner parts of the sealoch systems was found to be highly impoverished with respect to infaunal diversity and abundance. The Neopentadactyla mixta coarse sediment biotope (SS.SCS.CCS.Nmix) was only tentatively identified due to the lack of evidence of the presence of the characterising holothurians. However, it is probably present in all regions of the survey area, apart from Loch Broom. ii The presence of maerl beds was confirmed in all regions apart from Loch Broom. Maerl in the Loch Gairloch area was more extensive than previous records suggest, with a coastal band continuing southwards beyond the mouth of the loch and also present to the north of the loch. On the other hand, the bed off Poolewe in Loch Ewe was found to be extensive but of poor quality, with live maerl content much lower than previous records suggest. The 2010 survey confirmed the widespread occurrence of maerl around the Summer Isles (chiefly as SS.SMp.Mrl.Pcal.R) and in Gruinard Bay (as SS.SMp.Mrl.Pcal.Nmix). A previously recorded maerl bed at Badluarach near the mouth of Little Loch Broom was found in 2010 to be one of the richest maerl beds observed in the search area in terms of maerl density and infaunal diversity. The only recorded presence of a flame shell bed (SS.SMx.IMx.Lim) was at Sruth Lagaidh Narrows in Loch Broom. This was mapped and the extent estimated as 7 ha, making it one of the smaller UK beds. Although the flame shell bed biotope was previously reported to be present at Badluarach, in association with the maerl bed, in 2010 only juvenile Limaria hians were present and no Limaria-structured habitat was recognisable. Flame shell beds reported from the Carn Skerries were not refound. Seagrass beds of Zostera marina (SS.SMp.SSgr.Zmar) were located in north-west Loch Gairloch and south-east Gruinard Bay, where distributional studies revealed the habitat to be more widespread than previous studies have shown. Although patchy, seagrass density was locally abundant at both locations and these beds are possibly the richest examples on the mainland coastline of northern Scotland from at least Loch Alsh to the Moray Firth. Locations of historical records of Ostrea edulis were investigated in Loch Thùrnaig (Loch Ewe) and in Old Dornie Harbour in the north of the study area. Only old, eroded, empty shells were found in Old Dornie Harbour but a small patch of live oysters was present on the lower shore in the very sheltered embayment, Ob na Bà Ruaidhe, in north-west Loch Thùrnaig. Oyster density was too low for the area to be considered an oyster bed. Large beds of sea loch egg wrack Ascophyllum nodosum ecad mackaii (also known as wig wrack) were identified and mapped in Badachro Bay (Loch Gairloch) and Loch Thùrnaig, and a new instance of this habitat, LR.LLR.FVS.Ascmac, recorded in Old Dornie Harbour. The 2010 survey provides the first indication of the distribution and composition of these beds. Fields of Leptometra celtica were observed in the locations of earlier records at the mouth of Loch Broom and on the inner and outer sills of Little Loch Broom, attaining a very high density on the outer sill. The known distribution of the species was extended by several new records of its occurrence on deep mud in the outer embayment of the study area and off the mouth of Loch Gairloch. Despite the examination of sites of historical records, no evidence of the presence of several MPA search features was obtained in 2010. These habitats included horse mussel beds (SS.SBR.SMus.ModHAs), inshore deep mud with burrowing heart urchins (SS.SMu.CFiMu.BlyrAchi) and Laminaria hyperborea on tide-swept, infralittoral mixed substrata (IR.MIR.KR.LhypTX). Also, historical records of the MPA search feature species, Palinurus elephas, Glossus humanus and Atrina fragilis were not validated. For further information on this project contact: Colin Trigg, Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW Tel: 01463-725014 For further information on the SNH Research & Technical Support Programme contact: DSU (Policy and Advice Directorate), Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW Tel: 01463 725000 or [email protected] iii Contents Page 1 INTRODUCTION............................................................................................................. 1 1.1 The Ullapool Approaches........................................................................................ 1 1.2 Previous surveys..................................................................................................... 2 1.3 Priority Marine Features (PMFs) and MPA search features.................................... 2 1.4 Geodiversity features.............................................................................................. 5 1.5 Related human activities ......................................................................................... 6 1.6 Survey objectives.................................................................................................... 7 2 METHODS ...................................................................................................................... 8 2.1 Video survey............................................................................................................8 2.2 Still photo survey..................................................................................................... 9 2.3 Infaunal survey........................................................................................................ 9 2.4 Multi grab survey................................................................................................... 10 2.5 Localised surveys.................................................................................................. 10 2.5.1 Badluarach, Little Loch Broom (maerl, flame shell beds).............................. 10 2.5.2 Poolewe, Loch Ewe (maerl, flame shell beds)..............................................