2014 NE Morecambe Bay SAC Subtidal Cobble & Boulder Skear Communities Drop-Video Survey

notPlanned

"Morecambe Bay is an ecologically diverse area, encompassing the coastal plain estuaries of the rivers Wyre, Lune, Keer, Kent and Leven which form an extensive area of shallow coastal sediments (Sotheran and Walton, 1997). The Morecambe Bay Special Area of Conservation (SAC) was designated under the Natura 2000 programme in 2005 due to the substantial amounts of Annex I habitat present within the Bay which include; estuaries, mudflats and sandflats not covered by water at low tide, large shallow inlets and bays, sandbanks which are slightly covered by sea water all the time and reefs.order to inform site condition monitoring, Seastar Survey Ltd. were contracted by Natural England to undertake a drop-down camera survey in the Morecambe Bay SAC in order to define the distribution and extent of any subtidal cobble and boulder skear communities present. dMain findings d{A total of 71 transects were attempted throughout the survey areas using Seastar Surveys own HD Freshwater Lens Camera System (FLCS), with a total of 528 discrete video clips achieved, 500 of which yielded usable data. d{The most commonly identified broad habitat was SS.SSa (sublittoral sands and muddy sands) with 35.5 % of seabed contacts assigned to either the broad habitat SS.SSa or the biotope complex SS.SSa.CMuSa (circalittoral muddy sand). Circalittoral mixed sediments (SS.SMx.CMxwere also frequently observed.cobble skear habitat was observed on 40 of the 71 achieved transects.skear polygons to delineate the extent of potential cobble skears were created at three confidence levels. The total area covered by potential cobble skear habitat (at 50 - 60 % confidence) was found to be approximately 6.26 km2, equivalent to 9.13 % of the total area surveyed.of potential cobble skear habitat were concentrated primarily near the mouth of Morecambe Bay (along the edge of the SAC) and in the central and east region of Area 1. Percentage cobble coverage was found to be particularly high in Areas 2 and 3; high incidences of cobble substrate were also recorded on the plateau between Areas 2 and 3 and in the central region of Area 2. Smaller areas of potential skear habitat were also identified in the northwest corner of Area 1.occurrence of cobble skear within the Walney Channel (Area 4) was found to be chiefly confined to the northern section of the channel, although an area of cobble skear south of the entrance to the channel was also identified.potential cobbles and boulder skear habitats were observed, epifauna was dominated by the non-native, cryptogenic colonial ascidian Molgula manhattensis. These areas were assigned the biotope CR.HCR.XFa.Mol. Other fauna commonly observed included silt- and scour-resistant species such as the bryozoans Flustra foliacea and Alcyonidium diaphanum, hydroids such Sertularia spp. and Hydrallmania falacata and encrusting fauna such as Spirobranchus sp. and sponges. d"