2010 Scottish Natural Heritage (SNH) Lamlash Bay monitoring survey
Following proposals made by the Community of Arran Seabed Trust (COAST), a no take zone (NTZ) of 268 ha was established in the northern part of Lamlash Bay in 2008 under the Inshore Fishing (Scotland) Act 1984. Scottish Natural Heritage (SNH) has a commitment to contribute to monitoring the success of the management measures in delivering benefits to the subtidal habitats and species of the bay. Earlier surveys in 2008 and 2009 mapped the seabed habitats of Lamlash Bay and surrounding waters. The aim of the study described in this report was to refine the biotope mapping within and immediately adjacent to the NTZ, to design a monitoring programme for the NTZ and to conduct baseline monitoring. The baseline survey and monitoring programme focuses on benthic habitats and sessile and low mobility species although highly mobile species (e.g. fish species) were also noted. A combination of methods, including remote video, remote stills, grab sampling and diving, were employed to collect this baseline data. The baseline monitoring survey was conducted between the 21st August and the 4th September 2010. All survey work was conducted from Marine Bio-images road-trailable vessel Freyja, a 5.4m Avon rigid hulled inflatable. In order to identify suitable areas in which to locate monitoring stations it was first necessary to refine the biotope maps produced in the earlier survey (Axelsson et al., 2010). In particular, the Phymatolithon calcareum maerl bed biotope (SS.SMp.Mrl.Pcal) provisionally mapped were expected to be the highest priority and so identifying the boundaries of the bed was prioritised. As a deeper draft vessel was used for mapping during the earlier survey it was also necessary to complete the mapping exercise in the shallow areas that had not been covered. Once this mapping was achieved 12 dive monitoring stations and 12 grab stations were identified, plus 20 stations for towed video and stills. The locations of these were evenly split between inside and outside the NTZ to provide comparative data.
dataset
GB-SCT-SNH-ME-000144-MRSNH02100000002-LB
eng
urn:ogc:def:crs:EPSG::4277
Munro, C.D., Baldock, L., Brown, K. and Lindsley-Leake, S.2014. Lamlash Bay, Arran,2010 survey report. Scottish Natural Heritage Commissioned Report No.619.
geoscientificInformation
biota
biota
revision
2008-01-06
revision
2009-11-16
creation
2011-01-20
creation
2011-02-16
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2003-01-01
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2011-07-06
creation
2012-02-14
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2012-03-16
revision
2005-04-27
creation
2006-08-31
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2017-05-12
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creation
2009-06-18
Irish Sea
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1954-01-01
Inner Seas off the West Coast of Scotland
revision
2010-01-01
circalittoral
revision
2010-01-01
infralittoral
2010-08-22
2010-09-04
publication
2011-01-22
notPlanned
Biotope mapping using drop-video and grabbing Biotope mapping was conducted using a combination of remote video and grab sampling. The earlier maps produced by SeaStar (Axelsson et al., 2010) were used as a starting point but were not incorporated in to the final map due to differences in methodology and findings. The key purpose of this was to better define the maerl biotope SS.SMp.Mrl.Pcal (Phymatolithon calcareum maerl beds in infralittoral clean gravel or coarse sand), which was considered the priority habitat. Areas identified as SS.SMp.Mrl.Pcal had been mapped within and to the north of the NTZ, but the 2008-09 broadscale mapping surveys did not cover some shallow areas due to the vessel draught restrictions. As maerl can flourish in shallow areas where light levels are higher it was possible the bed extended considerably in to this un-surveyed area. A hand deployed drop-video system and hand deployed Van Veen grab (0.025 m2 surface area) were using to provide rapid coverage. Working from a small RIB allowed the system to be deployed in less than 2 m water depth. A Sony DCR-PC110E DV camera recorder within a Gates housing with super-wide dome port, linked by umbilical to an LCD surface monitor was used for viewing video images. This was deployed by hand in a lightweight frame. The video was allowed to drift across the seabed for a few minutes, approximately 20 cm off the bottom although this varied depending on sea conditions. The live picture was viewed on a surface monitor by one surveyor who gave a commentary describing the seabed and species observed. This was transcribed in to a field notepad by a second surveyor. For the purpose of biotope mapping, when taken, grab sample contents were subject to rapid assessment only. Data was plotted each evening to produce working maps of the seabed habitats. Dive monitoring Once the mapping exercise was completed the data generated was used to help select suitable locations for dive monitoring stations. Twelve dive stations were selected; six within the NTZ and six outside but in similar depths and on similar habitat. The diving focused on the shallower parts of the bay, thus giving maximum return in terms of the amount of time that could be spent underwater and so the amount of data collected. All monitoring dives were conducted between 5-14 m sea level (2-12 m chart datum). Each dive station was located using GPS. A shot line marked with a surface buoy was then deployed to ensure the divers descended on the exact location. A four person dive team was used for this operation; operating as two dive pairs. Whilst one pair dived the other worked as supervisor and boat handler. Once on the seabed the divers reeled out a 12 m long tape, marking a survey transect on the seabed. Ten metres of this transect was then filmed down one side (right-hand side, travelling away the base of the shot line), the transect starting 2 m out from the shot line. Once this was completed the diver then surveyed along the length of the transect line, recording habitat type and conspicuous species (using the MNCR SACFOR semi-abundance scale). The distant end of the transect was then picked up and the transect line rotated anti-clockwise 6-7 m, then re-deployed and the video and visual survey repeated. Once complete the transect was lifted and moved as before and a third transect surveyed. Starting 2 m out from the base of the shot line ensured the same area close to the shot was not resurveyed. The second diver dropped a 0.5 x 0.5 m quadrat from about 1.5 m above the seabed, ensuring it landed at a random location. The quadrat was then photographed from approximately 60-80 cm above the seabed, using a housed DSLR fitted with a wide-angle lens and twin strobes. This process was repeated, the quadrat being picked up and dropped again, until eight quadrats had been photographed. This was conducted within a radius of 6 m from the shot line. Quadrats marked along all sides at 10 cm intervals were used to aid subsequent counts and estimates of percentage cover. Where possible all identification was done in situ. Small plastic bags were used to collect any specimens where in situ identification was uncertain. These were examined (under low power or compound microscope if necessary) with reference to standard text, and by other team members, in the evening. All identification was standardised using the World Register of Marine Species (Worms) nomenclature (Appeltans et al., 2011) Once both above tasks were completed all equipment was collected at the base of the shot line and a single core collected. A plastic tubing core (10.3 cm internal diameter, 25 cm long) was used. This was pressed 15 cm in to the sediment before being dug out by hand, or trowel if very compacted), bungs fitted and placed in a net bag. Due to the shell and gravel content of the sediment at many sites a lump hammer was generally required to push the core in 15 cm. Grab sampling monitoring Grab sampling monitoring stations were located in the deeper areas of the bay where dive time would be limited and so diving less cost-effective. The depth range was 17-30m. As these areas were primarily softer, muddier habitats grab sampling was an appropriate method here. A hand deployed Van Veen grab (0.025 m2 surface area) was used to collect samples. Infaunal samples were collected at all 12 grab sampling stations. Samples were placed in to labelled buckets on board the survey boat, then sieved at the shoreline when the boat returned to the slipway at the end of each day. Samples were sieved through a 0.5 mm mesh and material retained on the mesh was transferred to labelled, lidded buckets. Buffered formalin was added to prevent dissolution of shells. Samples were subsequently transported to the Aquatonics Ltd laboratory at the end of fieldwork for infaunal analysis. At six of the stations (stations 2, 4, 6, 8, 10 and 12) a second grab sample was collected for particle size analysis (PSA) and organic carbon content. These samples were stored in labelled plastic bags and frozen at the end of the day. At the end of fieldwork these samples were transferred to the laboratory for PSA and organic carbon analysis. Towed video and stills monitoring To describe the habitat surface features and epifauna in the deeper, central part of the NTZ and adjacent areas a series of short tows, combining video and still images, were conducted. A 10 megapixel digital stills camera was mounted parallel to the video camera on the drop-video system. The camera system was allowed to drift slowly across the seabed for approximately 3 minutes. Stills were taken every 10 seconds; this allowed between 20 and 25 stills to be taken on most transects, varying slightly with conditions. A total of 20 transects were completed (identified as TR12-TR31). Video images were captured on miniDV tape; stills were captured as high resolution JPEGs on SD memory card, then downloaded on to a laptop hard drive each evening. Video was viewed on a surface monitor during each tow. General habitat description and conspicuous species notes were made. A visual check was also made that the stills camera strobes were firing. All video footage was subsequently viewed on a 17 inch computer monitor. Each tow was inspected with more detailed notes made whilst viewing, supplementing the earlier field notes. All identifiable species were recorded and, where possible, MNCR SACFOR abundances given. All stills from each tow were also viewed on a large monitor, habitat descriptions compared with those derived from video footage and notes amended if necessary. Similarly, stills images were inspected and all identifiable species noted. Numbers of individuals noted within all stills from a given tow were used to derive MNCR SACFOR abundances. These values were compared with abundances derived from video analysis and any adjustments considered necessary were made, with judgements being made as to which method provided the better data for a given species. Infaunal analysis Once core and grab samples arrived at laboratory, each sample was washed through a 0.5 mm mesh to remove the formalin. The lighter fraction was transferred to a 0.5 mm sieve by repeated elutriation of the sample. This lighter fraction contained most of the taxa present in the sample. The dense fraction was in some cases sieved through a nest of sieves (4 mm, 2 mm, 1 mm and 0.5 mm) to aid sample sorting and removal of specimens. Difficult specimens (e.g. many syllid and maldanid polychaetes) were sent away for confirmation or identification. The QA process showed that there was some difficulty in distinguishing between the spionid polychaetes Prionospio fallax and Minuspio cirrifera. Consequently the results for these two species have been combined. The external QA also showed that some of the Nucula nucleus reported may include some Nucula nitidosa and Nuculoma tenuis. The sample sorting took significantly longer than expected, in most cases a full day was required to sort a sample. Identification of specimens from a sample took 2-4 days, with most samples taking approximately 3 days. The long time required was due to large quantities of coarse material in most samples to examine (all except the 4 mm fraction was sorted under a binocular microscope) and the large number of taxa and specimens present. Particle size analysis and organic carbon analysis Particle size analysis: Sediments were stored frozen after receipt at the laboratory until analysed. Sediment samples were 0.5 to 1 kg in weight and contained a significant gravel content (30-60%). No bulk sub-sampling procedure was deemed necessary due to sample size. On defrosting, all samples were inspected to see if they needed wet sieving (i.e. contained more than about 5% mud). Samples assessed for dry sieving only were processed to quantitatively determine the particle size distribution of the sand fraction (0.063 -2 mm) and gravel fraction (more than 2 mm) using a dry sieving method. A sample of the fine material passing the 63 micron sieve was collected for organic carbon analysis (see section 2.6.2). Those samples assessed for wet sieving were processed, then the sand fraction dry-sieved. Identical subsamples for pipette analysis (particle-size of mud) and organic carbon analysis were retrieved during the wet sieving process. Particle-size statistics were generated using Gravistat software. This methodology is based on British Standard 1377 parts 1 and 2 (British Standards Institute, 1990). Organic Carbon Analysis - Standardisation of ferrous sulphate: Ten millilitres of the normal potassium dichromate solution was run from a burette into a 0.5 litre beaker. Twenty millilitres of concentrated sulphuric acid was then added, swirled and allowed to cool for some minutes. Two hundred millilitres of distilled water, 10 ml of orthophosporic acid and 2 ml of redox indicator were then added. This was then set to stir on a magnetic stirrer. Ferrous sulphate was then added from a second burette until the colour of the solution changes from blue-green to red. A further 0.5 ml of potassium dichromate was then added, turning the colour back to blue-green. Ferrous sulphate was then added drop by drop, with the stirrer operating, until the single drop when the colour changed back to red. The total volume of ferrous sulphate used (x) was recorded, to the nearest 0.05 ml. About 1 g of the oven dried less than 63 micron sediment was weighed to an accuracy of 4 decimal points, and added to a 0.5 litre beaker. Non-organic carbon (carbonate) was removed using the method of Shaw (1959). 25 ml of sulphurous acid was added to each 25 ml beaker (sufficient for 1 g of carbonate, although checking takes place) and swirled thoroughly and left for 3 hours minimum. The mixture is then placed in an oven at 60 degrees celcius until dry. Sample titrations were then prepared. The total volume of potassium dichromate used in the oxidation of the organic matter in the sediment was determined by: 10.5 X (1-y/x) ml (x = total volume of ferrous sulphate in the standardisation test; y = total volume of ferrous sulphate used) The correct results are only given if this value lies between 5 and 8 ml. Analyses were repeated if necessary to give a volume-used value in the correct range (high value: less sediment weighed in; low value: more sediment weighed in). The results were calibrated against an MESS2 standard of known organic content and the results calibrated accordingly. This methodology is based on British Standard BS 1377 (British Standards Institute, 1990). Additional dive sites S1 and S3 Two additional dive locations were dived on completion of all dive monitoring stations. These were locations proposed by SNH as anecdotal reports and indirect evidence (apparent dredge scars on sidescan sonar) suggested there had been some scallop dredging activity in both vicinities. These dive sites are recorded as S1 (dive 13) and S3 (dive 14). Dive site S1 is located approximately 0.64 km NNW of Clauchlands Point (mid-point approximately 55.555880N 05.080222W, WGS84), in approximately 17-20 m chart datum on a gently sloping mixed sediment plain; Dive S3 is located approximately 0.41 km WSW of Clauchlands Point (55.548798N 05.076445W) in approximately 27-28 m chart datum on a level, mixed sediment seabed consisting of stone and shell gravel and sand with occasional boulders. A single dive was conducted at each site, the dive pair swimming in a random direction. General notes on the sediment type and topography and site condition were made, species were recorded using MNCR SACFOR abundance scales. Representative stills photographs were taken at both sites.
publication
2011-02-02
true
See the referenced specification
publication
2023-05-11
true
See the referenced specification
Not for navigational use; SNH copyright data which is available for re-use under government licence terms: http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
Sensitive species and or habitat was recorded during survey. As such NatureScot would not release such records in response to an Environmental Information (Scotland) Regulations 2004 request at a resolution below that provided by a 20km by 20km.
Marine Ecological Solutions
dorsetseasearchdiving@gmail.com
originator
Marine Biological Surveys
originator
Data Manager
Scottish Natural Heritage (SNH), Headquaters
Great Glen House, Leachkin Road
Inverness
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01463 725000
custodian
Data Manager
Scottish Natural Heritage (SNH), Headquaters
Great Glen House, Leachkin Road
Inverness
IV3 8NW
01463 725000
pointOfContact
2024-03-12