2009 Defra MB0102 2C Potential distribution of tideswept communities in the UK and Isle of Man based on modelled data using a 3knot cutoff

This layer shows the area in which tideswept communities habitat, a Biodiversity Action Plan habitat is likely to occur. Method: Using the Maximum Tidal Bed Shear Stress layer (resulting from MB0102 2E.3) from ABPmer, exposure >1.8 Nm-2 ('moderate' and greater bed stress shear; EUNIS-UK classification) was extracted from raster. Assuming that current at depth is approximately half that of the surface (Hiscock, 1975) and using the Maximum Current Magnitude layer (resulting from MB0102 2E.2), areas of surface current of magnitudes greater than 3 knots (a 1.5 multiplication of modeled sea bed currents) were extracted from the raster. Areas with corresponding tidal bed stress greater than 1.8 Nm-2 and maximum current magnitude greater than 3 knots on the surface were classified as potential tide swept communities. The layers on which this data is derived do not provide sufficient inshore coverage and this layer is therefore limited. This layer forms one of a set of data layers created for the Defra MB0102 contract. This work will support the delivery of a network of Marine Protected Areas as required to meet existing international and national obligations and commitments, including Marine Conservation Zones (MCZs), a new measure to be delivered as part of the Marine and Coastal Access Bill, and equivalent measures under Scottish legislation. The availability of these data layers will also be of importance in underpinning Marine Planning (e.g. licensing) in our marine area.