Seagrass Potential

Seagrass Potential Summary: Seagrass potential areas derived from wave and current energy, elevation and salinity criteria. Guidance and Limitations: The Seagrass Potential Area layer provides a national ‘high level’ indication of where intertidal and subtidal seagrass could potentially be restored based on some key physical attributes. It should be considered as an initial aid to identifying sites. The areas identified are based on outputs from large scale models and should not always be assumed to precise at the local level. The location of significant activities (such as dredging) and marine assets (such as submarine cables), which could restrain a location’s potential, have not been factored in in the creation of this layer. The presence of such activities and structures should of course be considered at an early stage before making any local selection of suitable sites. It should not be assumed that all the areas identified meet all environmental conditions required to re-establish seagrass habitat or that seagrass beds currently only exist within these areas. Instead it aims to provide an initial attempt to identify potential areas at a national level. Furthermore, it is probable that there are some areas outside the areas identified that could be suitable for restoration. The data is not directly derived from any specific historic records of seagrass, and does not represent the historic extent of seagrass. Seagrass Potential Description: Seagrass potential areas were primarily derived from the EMODnet 2016 wave and current energy models. This data was combined with seabed digital elevation models (DEMs sourced from Defra Marine DEM and EMODnet Composite 2018 DTM) and Environment Agency turbidity data to determine potential seagrass habitat areas. Areas of low salinity were also screened out based on Environment Agency salinity monitoring and modelling data. Selection Criteria used habitat preferences for Zostera marina and Z. noltei identified by the Marine Life Information Network (MarLIN) as follows: Wave = Low Energy, <11.41 Nm-2 (mean of annual 90th percentile values over six years) Current = Low Energy, <130 Nm-2, (mean of annual 90th percentile values over six years) Elevation (waterbodies with low turbidity <10mg/l) = Between -10m and +5m above sea level. Elevation (waterbodies with medium and high turbidity >10mg/l) = Between -5m and +5m above sea level. Salinity = >10 (mesohaline, polyhaline) Further areas were removed, including existing saltmarsh (sourced from EA saltmarsh extent inventory) and small discrete areas <400m2. Small areas were also removed based on expert judgement and their close proximity to major ports. Finally, each polygon was assigned a water body and river basin district based on the WFD cycle2 Transitional and Coastal Water Body layer. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved.