Data from: Seagrasses in coastal wetlands of the Algarve region (southern Portugal): past and present distribution and extent

These datasets support the scientific article "Seagrasses in coastal wetlands of the Algarve region (southern Portugal): past and present distribution and area extent" published in 2025 (Journal of Sea Research, 205, 102580; https://doi.org/10.1016/j.seares.2025.102580). It contains detailed data on the distribution and area extent of intertidal and subtidal seagrass meadows in the four main wetlands of the Algarve region (Southern Portugal): Ria de Alvor, Arade Estuary, Ria Formosa, Guadiana Estuary. The data is composed by 5 datasets with the following variables: 1) data_field_points.csv Contains data points based on field surveys. dataset_id [character] - Unique identifier for the data set. data_id [character] - Unique identifier for the data point. wetland [character] - Wetland full name, in Portuguese: Ria de Alvor, Estuário do Arade, Ria Formosa, Estuário do Guadiana. wetland_slug [character] - Short name of the wetland for coding purposes: alvor, arade, riaformosa, guadiana. quadrat_id [character] - Name of the quadrat as recorded in the field. photo_id [character] - Name of the pictured associated to the observation. sampling_id - Name of the observation as recorded in the field. date [date] - Date of observation (YYYY-MM-DD). year [integer] - Year of sample collection (YYYY). month [integer] - Month of sample collection (MM). latitude [numeric] - The geographic latitude (in decimal degrees, WGS84) of data point. longitude [numeric] - The geographic longitude (in decimal degrees, WGS84) of data point. habitat_class [factor] - Type of habitat: unvegetated, seagrass intertidal, seagrass subtidal, seagrass unknown, salt marsh low, caulerpa. species [factor] - Vegetation species: No vegetation, Zostera noltei, Zostera marina, Cymodocea nodosa, unspecified species, Caulerpa prolifera, Sporobolus maritimus. notes [character] - Any relevant notes on the data compilation. method [factor] - Method used for the observation: boat and camera, boat and snorkelling, kayak and camera, on foot. survey_area [character] - Number of the survey area. site [character] - Name of the site. observers [character] - Name of the researcher(s) who collected the data. 2) data_compilation_records.csv Contains information on the records (i.e. sources) screened during the systematic review for the compilation od seagrass occurrence data. record_id [character] - unique id for the compiled records. short_citation [character] - short citation of the record, with author and publication year. included [boolean] - whereas the record was used to extract data or informacion. record_type [factor] - type of record: journal article, book or book chapter, PhD or MSc thesis, report, others. publication_year [integer] - year of the publication of the record, YYYY. title_record [character] - title of the record. link [character] - link to access the record, if available (DOI, handle, others URLs). full_citation [character] - full citation of the record, with authors, publication year, title, etc. 3) data_compilation_points_raw.csv Contains data points of seagrass occurrence based on the systematic review. This is the original raw file with all the compiled points. data_id [character] - Unique identifier for the data point (same as used in data_compilation_clean.csv). included [boolean] - whether the data point was kept in the clean dataset or not: 1, the point has been validated and it is included in the final dataset; 0, the point is excluded due to unprecise location (on land, open ocean, etc.). reason_exclusion [character] - Reason to exclude the data point from the clean dataset. record_id [character] - unique id for the compiled record from where data was extracted (same as in data_compilation_records.csv). short_citation [character] - Short reference (author(s) and year) (same as in data_compilation_records.csv). wetland [character] - Wetland full name, in Portuguese: Ria de Alvor, Estuário do Arade, Ria Formosa, Estuário do Guadiana. wetland_slug [character] - Short name of the wetland for coding purposes: alvor, arade, riaformosa, guadiana. latitude [numeric] - The geographic latitude (in decimal degrees, WGS84) of data point. longitude [numeric] - The geographic longitude (in decimal degrees, WGS84) of data point. year [integer] - Year of sample collection (YYYY). month [integer] - Month of sample collection (MM). year_precision [character] - Precision of the year registred: exact, after, before, or aproximately. habitat_class [factor] - Type of seagrass habitat: seagrass intertidal, seagrass subtidal, or seagrass unknown. species [factor] - Dominant seagrass species: Zostera noltei, Zostera marina, Cymodocea nodosa, unspecified. collection_code [character] - The name identifying the data set or collection from which the record was derived. catalogue_number [character] - An identifier for the record within the data set or collection. original_id [character] - An identifier given to the occurrence at the time it was recorded (specimen collector's number or site collection). duplicated [boolean] - whether the data point was flagged as duplicated or not. 4) data_compilation_points_clean.csv Contains data points of seagrass occurrence based on the systematic review. This is the clean file after elimitating duplicates and points with unprobable or unprecise location. data_id [character] - Unique identifier for the data point (same as used in data_compilation_raw.csv). record_id [character] - unique id for the compiled record from where data was extracted (same as in data_compilation_records.csv). short_citation [character] - Short reference (author(s) and year) (same as in data_compilation_records.csv). wetland [character] - Wetland full name, in Portuguese: Ria de Alvor, Estuário do Arade, Ria Formosa, Estuário do Guadiana. wetland_slug [character] - Short name of the wetland for coding purposes: alvor, arade, riaformosa, guadiana. latitude [numeric] - The geographic latitude (in decimal degrees, WGS84) of data point. longitude [numeric] - The geographic longitude (in decimal degrees, WGS84) of data point. year [integer] - Year of sample collection (YYYY). month [integer] - Month of sample collection (MM). year_precision [character] - Precision of the year registred: exact, after, before, or aproximately. habitat_class [factor] - Type of seagrass habitat: seagrass intertidal, seagrass subtidal, or seagrass unknown. species [factor] - Dominant seagrass species: Zostera noltei, Zostera marina, Cymodocea nodosa, unspecified. collection_code [character] - The name identifying the data set or collection from which the record was derived. catalogue_number [character] - An identifier for the record within the data set or collection. original_id [character] - An identifier given to the occurrence at the time it was recorded (specimen collector's number or site collection). 5) data_compilation_extent.csv Contains area extent data of seagrass meadows based on the systematic review. data_id [character] - Unique identifier for the data. record_id [character] - unique id for the compiled record from where data was extracted. short_citation [character] - Short reference (author(s) and year). wetland [character] - Wetland full name, in Portuguese: Ria de Alvor, Estuário do Arade, Ria Formosa, Estuário do Guadiana. wetland_slug [character] - Short name of the wetland for coding purposes: alvor, arade, riaformosa, guadiana. value [boolean] - whether the data extracted from the record is a extent value (i.e., a value of area covered by seagrasses). polygon [boolean] - whether the data extracted from the record is a polygon. year [integer] - Year of sample collection (YYYY). month [integer] - Month of sample collection (MM). year_precision [character] - Precision of the year registred: exact, after, before, or aproximately. habitat_class [factor] - Type of seagrass habitat: seagrass intertidal, seagrass subtidal, or seagrass unknown. species [factor] - Dominant seagrass species: Zostera noltei, Zostera marina, Cymodocea nodosa, unspecified. area_source [numeric] - The area extent given in the record. area_source_cover [factor] - The cover of the wetland for the compiled extent from the record means: total, partial or unknown. area_gis [numeric] - The area extent obtained using GIS. area_gis_cover [factor] - The cover of the wetland for the obtained extent from GIS means: total, partial or unknown. notes [character] - Any relevant notes on the data compilation.