Alternate title

GB001300

Date (Creation)

2013-06-25

Date (Publication)

2018-04-26

Citation identifier

EMODnetSeabedHabitats / GB001300

Point of contact

Organisation name	Individual name	Electronic mail address	Role
Defra		open@defra.gsi.gov.uk	Owner
Natural England		enquiries@naturalengland.org.uk	Custodian

GEMET - INSPIRE themes, version 1.0

• Habitats and biotopes

http://inspire.ec.europa.eu/codelist/ReferenceHabitatTypeSchemeValue

• Eunis

Use limitation

┬® Defra. Data may be re-used under the terms of the Open Government Licence.

Use limitation

geossAttribution

Access constraints

Other restrictions

Other constraints

no limitation

Spatial representation type

Vector

Denominator

50000

Language

English

Topic category

• Biota
• Oceans

Begin date

2013-01-01

End date

2013-12-31

Supplemental Information

Murray, J., Downie, A. (2014) Mounts Bay rMCZ Post-survey Site Report. Defra Contract Reference: MB0120. Report Number: 15. Version 5. Available from: http://randd.defra.gov.uk/Document.aspx?Document=12843_MountsBayrMCZ_SummarySiteReport_V5.pdf

Reference system identifier

EPSG / WGS 84 (EPSG:4326) / 7.9

Topology level

Geometry only

Distribution format

Name	Version
ESRI Shapefile	1.0

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--link	http://randd.defra.gov.uk/Document.aspx?Document=12843_MountsBayrMCZ_SummarySiteReport_V5.pdf	Mounts Bay rMCZ site report
WWW:LINK-1.0-http--link	https://www.emodnet-seabedhabitats.eu/access-data/launch-map-viewer/?zoom=13&center=-5.46366,50.11274&layerIds=501&baseLayerId=1&activeFilters=NobwRANghgngpgJwJIBMwC4CsAGAjAGjADMBLCAF0VQwBYB2Q0ixAGQHs2BrAVwAdUAzhmABdRmUoIAKnAAe5DGADiAIWx4AzOrABfEUA	EMODnet Seabed Habitats Map Viewer
OGC:WMS	https://ows.emodnet-seabedhabitats.eu/geoserver/emodnet_view_maplibrary/wms?	gb001300
OGC:WFS	https://ows.emodnet-seabedhabitats.eu/geoserver/emodnet_open_maplibrary/wfs?	gb001300
WWW:LINK-1.0-http--link	https://files.emodnet-seabedhabitats.eu/data/EMODnetSBHsurvey_GB001300.zip	EMODnet Seabed Habitats download

Hierarchy level

Dataset

Statement

The majority of the Mounts Bay rMCZ overlaps with an area of existing Multibeam Echosounder (MBES) bathymetry and backscatter data acquired by the Maritime and Coastguard Agency (MCA) under the CHP. Consequently no dedicated acoustic data were acquired for the site.

Sampling equipment comprised a 0.1 m 2 Day Grab. On recovery, the grab sample was emptied into a large plastic bin and a representative sub-sample of sediment (approx. 0.5 litres) taken for Particle Size Analysis (PSA). The remaining sample was photographed and sieved over a 1 mm mesh sieve to collect the benthic fauna. Fauna were preserved in buffered 4% formaldehyde for later processing ashore. Video footage and still images of the seabed were collected with an underwater camera system. The camera images helped to characterise surficial sediments and associated epifaunal communities. The camera system was mounted on a drop down frame with two high intensity LED strip lights, and collected both video and still images. A reference scale was used in Mounts Bay rMCZ: Post-survey Site Report 8 the video and still images. Set-up and operation followed the MESH ÔÇÿRecommended Operating Guidelines (ROG) for underwater video and photographic imaging techniquesÔÇÖ (Coggan et al., 2007). Video was recorded simultaneously to a Sony GV-HD700 DV tape and a computer hard drive. A video overlay was used to provide station metadata, time and GPS position (of the vessel) in the recorded video image. Camera tows lasted a minimum of 10 minutes, with the sledge towed at ca. 0.5 knots (ca. 0.25 m s ÔÇô1 ) across a 100 m diameter ÔÇÿbullringÔÇÖ centred on the sampling station. Still images were captured at regular 10-15 m intervals and also opportunistically if specific features of interest were encountered. Video and still images were analysed following an established protocol used by Cefas and the Joint Nature Conservation Committee.

A new habitat map for the site was produced by analysing and interpreting available acoustic data and the ground-truth data collected by the dedicated survey of the site. The new habitat map was produced via object-based image analysis (OBIA) implemented in the software package eCognition® v8.7.2. OBIA is a two-step process consisting of the segmentation and classification of an image based on its spectral characteristics (Blaschke, 2010). Acoustic spectrum data are initially reinterpreted as visual data layers of bathymetry, backscatter and their derivatives. Subsequent segmentation divides the data into meaningful uniform subareas, called objects, and these can be characterised by their various features, such as layer values (mean, standard deviation, skewness, etc.), geometry (extent, shape, etc.), texture, and many others. The subsequent classification of objects is based on combinations of these features.

It was possible to distinguish four distinct types of BSH from the acoustic and ground-truthing data. Extensive outcrops of ÔÇÿHighÔÇÖ and ÔÇÿModerate energy infralittoral rockÔÇÖ (A3.1 and A3.2) were found in the area, interspersed with ÔÇÿCoarse/Mixed sedimentsÔÇÖ (A5.1/A5.4) and surrounded by areas of ÔÇÿSublittoral sandÔÇÖ (A5.2). The distribution of values for bathymetry, its derivatives and backscatter, in the broad-scale habitat classes found in ground-truth data, were analysed to find the variables that best distinguished habitat classes. Data from video and still images were used to characterise the hard substratum classes ÔÇÿA3.1 High energy infralittoral rockÔÇÖ and ÔÇÿA3.2 Moderate energy infralittoral rockÔÇÖ, as well as ÔÇÿA5.1 Subtidal coarse Mounts Bay rMCZ: Post-survey Site Report 11 sedimentÔÇÖ and ÔÇÿA5.4 Subtidal mixed sedimentÔÇÖ. Coarse and mixed sediments were only observed in the video transects. Due to the very similar nature of their recorded substrate composition, and the fact that no PSA samples existed of either of the sediment categories, coarse and mixed sediments were described as a complex of the two habitats. PSA data from grab samples were used to classify the ÔÇÿA5.2 Subtidal sandÔÇÖ BSH observed in the area. Patches of ÔÇÿSublittoral sandÔÇÖ (A5.2) were identifiable by their much lower backscatter and low surface relief, whereas ÔÇÿHighÔÇÖ and ÔÇÿModerate energy infralittoral rockÔÇÖ (A3.1 and A3.2) were characterised by highly rugose bottom topography accompanied by high reflectivity. The energy level of rock habitats was determined by depth. High reflectivity coupled with low rugosity was found to indicate ÔÇÿCoarseÔÇÖ and ÔÇÿMixed sedimentÔÇÖ bottoms (A5.1/A5.4). Consequently, objects with high rugosity values above 18m depth were classified as ÔÇÿHigh energy infralittoral rockÔÇÖ and below 18m as ÔÇÿModerate energy infralittoral rockÔÇÖ. The remaining lower rugosity area was classified into ÔÇÿSublittoral sandÔÇÖ and ÔÇÿCoarse/Mixed sedimentÔÇÖ based on backscatter intensity. Not enough data were available for external validation of the updated map.

Metadata

File identifier

a9611f16-8717-44a1-a45c-0884c2e90bc3 XML

Metadata language

English

Character set

MD_CharacterSetCode_utf8

Hierarchy level

Dataset

Date stamp

2020-01-15T12:09:04

Metadata standard name

ISO19115

Metadata standard version

2003/Cor.1:2006

Metadata author

Organisation name	Individual name	Electronic mail address	Role
JNCC		HabitatMapping@jncc.gov.uk	Point of contact