This dataset includes empirical and qualitative data from a multitude of sources using systematic review methods to provide analysis on seagrass occurrence and loss in the United Kingdom. We document 8,493 ha of recently mapped seagrass in the UK since 1998. 

The purpose of the search was to extract qualitative and quantitative data on historic seagrass presence and trends of declines as far back as possible. To achieve this, we designed a search term that would capture all the literature on seagrass in the United Kingdom, including NOT terms to avoid irrelevant hits from places sharing part of their name with UK locations: 

(Seagrass OR zostera OR “zostera marina” OR “z. marina” OR “z. noltii” OR “zostera noltii”) AND (uk OR “united kingdom” OR “great britain” OR england OR wales OR scotland OR “northern Ireland” OR ireland OR “scilly isles” OR “isles of scilly” “isle of wight” OR guernsey OR jersey OR “isle of man”) NOT (“New England” OR “New Jersey” OR “New South Wales”)

The search term was entered into Web of Science, producing 160 papers. These were sifted by abstract based on the following criteria: 1) the paper refers to an area within the UK and; a) seagrass is the primary focus or; b) seagrass is the secondary focus but the primary focus suggests significant contribution of seagrass to the paper e.g. feeding habitats for wintering wildfowl; coastal WFD assessments; ecosystem services of coastal habitats. If there was any doubt that UK seagrass formed a significant contribution to any of the papers, it was also included for review Based on these criteria 59 papers were considered relevant for this work. The database of papers was synthesised for qualitative and quantitative data on seagrass presence, loss, and trends of changing distribution. Because these data were being used to supplement quantitative data on areal extent only, data on density and condition of seagrass meadows was not captured.