National Seagrass Layer (England)

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 best 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 ensure this can be accounted for.

As data is collected from/using a variety of sources and methods the accuracy of the data varies. A data confidence field is supplied to provide an indication of confidence in the data accuracy. Confidence categories are assigned based on expert judgement and local knowledge. Some historical data has a particularly low confidence and may be assigned with a category of ‘presence only’. Polygons with this confidence should only be used to identify previous seagrass presence, they should not be used to identify previous seagrass extent.

Metadata

This dataset contains a collation of current and historic seagrass data by Natural England and the Environment Agency. This includes data collected or commissioned by Natural England, the Environment Agency, or provided by third parties that have allowed their data to be republished under the Open Government Licence (OGL). The dataset identifies a current extent of seagrass which used the best available evidence and has been agreed by both Natural England and the Environment Agency. Before carrying out any analyses using this layer, the associated README file, which provides a list of dataset caveats, should be read.

Seagrass beds are an important resource for both carbon storage and biodiversity. They are a designated feature in a number of Marine Protected Areas, used to inform ecological assessment as part of the Water Framework Directive, and are the focus of habitat restoration schemes such as the LIFE Recreation ReMEDIES project.

This dataset contains records that qualify as open and therefore can be published under the Open Government Licence (OGL). These records are extracted and collated from the Environment Agency Seagrass Database and Natural England Marine Evidence Base (MEB), is a collated database of both NE and 3rd party surveys. All non-seagrass habitats are excluded from the Seagrass Layer, and datasets are clipped to English waters only. The Environment Agency WFD Areas dataset is used identify which area each seagrass bed lies within. Extraction of data from the NE Marine Evidence Base is based on the dataset identifier, access limitations and data owner as defined within the Marine Metadatabase to ensure that only open datasets are included in the open version. A full list of the survey datasets used in the production of this dataset can be found in the Survey Metadata sheet included with the download.

Attribution Statement: © Natural England © Environment Agency. Contains data from ©Joint Nature Conservation Committee © Isle of Wight County Council © Tim Allsop © Dr Ken Collins 2008 © Devon and Severn IFCA © South Devon Estuaries Partnership © Torbay Coast and Countryside Trust © Harwich Haven Authority © North Eastern Inshore Fisheries & Conservation Authority 2017 © Yorkshire Wildlife Trust © University of Plymouth © Cornwall Council © Tevi 2018

The MAGiC version also includes data not included in the download file from © Hampshire and Isle of Wight Wildlife.

Full layer symbology is available through download links.