Type of resources
Contact for the resource
A composite Habitats Directive Annex I feature extent map of Submarine structures made by leaking gases for the Scanner Pockmarks SAC was created by British Geological Survey for JNCC to provide the most up-to-date knowledge of Methane-Derived Authigenic Carbonate (MDAC) coverage within the site. Existing polygon data from the 2012 JNCC/CEFAS survey (CEND19x/12 ) was combined with information extracted from previous surveys. Backscatter data and side scan sonar data was used to characterise the nature of the seafloor, in particular the presence of methane-derived authigenic carbonate (MDAC), to build a composite understanding of ÔÇ£HighÔÇØ and ÔÇ£PotentialÔÇØ Annex I feature within the site.
A composite Habitats Directive Annex I feature extent map of Submarine structures made by leaking gases for the Braemar Pockmarks SAC was created by British Geological Survey for JNCC to provide the most up-to-date knowledge of Methane-Derived Authigenic Carbonate (MDAC) coverage within the site. Existing polygon data from the 2012 JNCC/CEFAS survey (CEND19x/12 ) was combined groundtruthing information (PB and BGS datasets), to build a composite understanding of ÔÇ£HighÔÇØ and ÔÇ£PotentialÔÇØ Annex I feature within the site.
Stanton Banks was designated as a Special Area of Conservation (SAC) through the Offshore Marine Conservation (Natural Habitats) Regulations 2007 and has now been accepted as a Site of Community Importance (SCI). The Joint Nature Conservation Committee (JNCC) in partnership with Cefas and supported by British Geological Survey (BGS) staff conducted a field survey to investigate the presence and extent of Annex I habitat features within the Stanton Banks SCI in order to facilitate discussions on possible fisheries management options. The survey was designed to acquire sufficient data to provide a robust characterisation of the Annex I rocky reef habitats, targeting areas of particular interest to fishers, and to contribute to the development of a robust baseline for future monitoring within the proposed SAC. In addition, the survey involved the characterisation and mapping of the sedimentary habitats surrounding the reef feature within the site boundary, in order to provide information on the wider environmental context.
The cruise took place between the 1st and 29th of July 2009 and surveyed two Areas of Search (AoS) for offshore Special Areas of Conservation (SACs): Anton Dohrn Seamount located 155km west of the St Kilda archipelago, and East Rockall Bank located 260km west of the St Kilda archipelago. The main aims of the survey were to acquire acoustic and photographic ?ground-truthing? data to enable geological, geomorphological and biological characterisation of the Anton Dohrn Seamount and East Rockall Bank AoS. Specifically, the data acquired will lead to the production of broadscale habitat maps, the identification and description of Annex I reef habitats with particular attention to the occurrence of bedrock, stony and biogenic reef, to identify and record any anthropogenic impacts in the areas of search and finally to evaluate data acquisition methods, techniques and equipment.
An ArcGIS polygon shapefile of the potential extent of Annex I sandbank habitat identified at Bassurelle Sandbank SCI was created using the data collected and processed as described below. EUNIS class assignments from the particle size data were used in conjunction with the interpreted still images to inform the semi-automated process of map production using object-based image analysis (OBIA), implemented in the software package eCognition v8.8.1. The OBIA was used to map habitats. It was not possible to use this technique for the mapping of Annex I habitats (specifically the sandbank feature at Bassurelle Sandbank SCI). Instead, an expert driven process of slope analysis in ArcGIS 9.3.1 and 3D visual interpretation using the Fledermaus v7 software package was used to identify the potential extent of the bank feature.
A composite Habitats Directive Annex I feature extent map of Submarine structures made by leaking gases for the Croker Carbonate Slabs cSAC/SCI was created by JNCC staff to provide the most up-to-date knowledge of MDAC coverage within the site. Existing polygon data from three previous surveys (CEND1108, CEND0513 and CEND2315) and habitat maps were combined with groundtruthing point information, to build a composite understanding of ÔÇ£HighÔÇØ and ÔÇ£PotentialÔÇØ Annex I feature within the site.
The purpose of this section of the project is to utilise the provided multibeam bathymetry and backscatter mosaic, processed sidescan sonar data layers and seabed substrate layers for integration and interpretation with other datasets to ultimately deliver seabed habitat data layers. JNCC required Fugro EMU to map the Annex 1 Reef habitat where possible and, where sufficient data exist, Annex 1 Reef subtypes. JNCC also require that a seabed habitat map is created to as detailed a hierarchical level as possible within EUNIS, where data are sufficient to enable this. The project report (14/J/3/02/2570/1626) details the methods used in analysing the data providedwith a specified level of confidence. The following deliverables were produced with the report: ÔÇó Derived data layers from MBES (hillshade, slope and rugosity) ÔÇó Seabed substrate data layer ÔÇó Seabed habitat data layers (including Annex 1 reef and reef subtypes and EUNIS) ÔÇó MEDIN metadata (xls/xml) All data have been referenced to the WGS84 datum.
It is widely recognised that M. modiolus reefs represent biodiversity ÔÇÿhotspotsÔÇÖ (e.g. Rees et al., 2008). In the Craigbrain and Burial Island Modiolus reefs, diversity indices from samples containing more than 9 live Modiolus per m2 showed numbers of taxa per sample ranging from 31 to 161, Shannon-Weiner diversity indices of between 2.0 and 4.3, and PielouÔÇÖs evenness index ranging from 0.52 to 0.95, which are all comparable to figures from similar open coast Modiolus reefs such as those of North Llyn and sites in Loch Alsh (see Fari├▒as-Franco et al., 2014). The diversity indices did not differ markedly from the surrounding area which is characterised by muddy sandy gravels with high shell content (mostly dead Modiolus shell), however the infaunal communities were significantly different between ÔÇ£Modiolus reefÔÇØ and ÔÇ£surrounding sedimentsÔÇØ (as determined through multivariate community analysis, including cluster analysis and ANOSIM routines). Due to inconsistencies in recording of epifaunal species from the grab samples, the epifaunal communities could not be statistically examined; however it was clear that there is a marked increase in the number of epifaunal species over the reef areas. Density of living Modiolus ranged from zero to 530 per m2 . These numbers are similar to those in other open coast reefs, such as the North Llyn beds (Fari├▒as-Franco et al., 2014), and the variation in numbers per m2 is indicative of the patchy nature of the reefs. The Craigbrain site appears to show the highest numbers of living Modiolus per m2 , however due to the limited number of samples and small areal coverage of grab samples it cannot be concluded that this reef site is markedly different from the Burial Island reef site, and the infaunal community analysis does not show statistically significant differences between the Craigbrain and Burial Island reef sites.