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National Seagrass Layer (England)

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A geospatial dataset providing a comprehensive record of current and historical seagrass surveys in English waters, produced jointly by Natural England and the Environment Agency. It identifies current seagrass extent using the most recent available evidence, compiling data collected or commissioned by Natural England, the Environment Agency, Defra and associated bodies, and third parties publishing under the Open Government Licence. The layer covers both Zostera sp. (eelgrass) and Ruppia sp., distinguishable by symbology or EUNIS HAB_TYPE codes. It contains only polygon data; absence of seagrass in a given area or year may reflect lack of survey coverage rather than true absence, and mapped extents can be affected by survey method.Overview Natural England and the Environment Agency have collaborated to produce a seagrass layer for English waters, which aims to provide a comprehensive geospatial dataset of surveys of both current and historical spatial seagrass. The layer also identifies a current seagrass extent, using the and most recent available evidence. The National Seagrass Layer is comprised of datasets collected or commissioned by Natural England and the Environment Agency, collected by Defra and associated bodies/agencies, or provided by third parties that have allowed their data to be republished under the Open Government Licence (OGL). Details of these third parties can be found in the accompanying metadata file. Caveats There are two genera of seagrass present in English waters: Ruppia sp. and Zostera sp. Commonly the use of ‘seagrass’ only refers to Zostera sp. (also known as Eelgrass). However, this dataset includes both Ruppia sp. and Zostera sp. If using the layer file, Ruppia sp. are identified by differing symbology. In the raw attribute data, Ruppia sp. and Zostera sp. can be distinguished using the EUNIS codes in the HAB_TYPE field. Seagrass data is only available where and when surveys have been carried out. Therefore, absence of seagrass in a specific year does not necessarily indicate that seagrass was not present, it may simply mean that no survey was completed that year. Similarly, there may be locations where seagrass is present, but has not been surveyed, and therefore is not represented in this dataset, such as the Medway Estuary. The seagrass layer only includes polygon data. There may be additional seagrass habitats which only have point data available, these are not included in the seagrass layer. Identified polygon extents may be affected by survey method. For example, a walking survey may not collect data below a certain depth, and a DDV survey from a boat may not collect data above a certain depth. A survey method field is included in the data, to.