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Specific freshwater dataset publishing considerations

Dataset preparation and standards

GBIF makes use of the Darwin Core Standard ([DwC]) to provide a standardized framework for formatting datasets for publication (see What is Darwin Core, and why does it matter?). DwC is a global standard that allows for integration of datasets from different sources through a common format and a number of required and recommended fields.

Though GBIF suggests the required and recommended fields for its four dataset classes, freshwater datasets need a few more specifications to form useful and reusable data for global analyses (see §2). In the following section we provide guidance on all mandatory and recommended terms of the different GBIF dataset classes and how they are best used when preparing freshwater datasets by giving freshwater-specific examples and recommendations. For some terms we suggest using selected terms only to improve consistency among datasets. To make freshwater dataset publication as easy as possible, we have also provided a Excel template for all dataset classes.

What is important for checklist and occurrence datasets is the inclusion of well-structured scientific names for taxa. When datasets are uploaded, the GBIF Backbone Taxonomy is used to check taxon names and update nomenclature as needed for consistency with current naming conventions. However, this process relies on a lack of ambiguity in the provided nomenclature. For example, taxonomic names at the genus or species level that are provided without any higher classifications (e.g. kingdom, class) may end up being misclassified by the taxonomic backbone if the same or similar species names are found in different kingdoms. This would result in inaccurate data. GBIF therefore recommends that users provide as much information as possible about higher classifications. Identification qualifiers (such as "cf."), working names, and common names should not be included in the term:dwc[scientificName] field, as these will not align with the taxonomic backbone and should instead be captured in the term:dwc[identificationQualifier] field. Author names are also an important component of scientific names to avoid misclassification, particularly for species-rich groups such as diatoms. The taxonomic authority (author who first published the species name following international rules) as well as the year of naming should be provided where possible, following the rules of author citation (learn about proper citation rules).

GBIF provides a species matching tool that allows users to normalize their species lists and ensure they match the taxonomic backbone in GBIF for data compatibility.

Checklist datasets

Checklist datasets are not necessarily specific to a location and do not always represent individual observations. However, they can be location specific (like the country-specific Global Register of Introduced and Invasive Species (GRIIS) checklists) and may contain occurrences (example). Checklist datasets may provide detailed information about species geographic distributions or species profiles that describe species characteristics.

Checklist datasets can be used to make it easier to select all freshwater assemblage data from a particular region, if a checklist of the freshwater species in the region is available. For more information on the possible types of checklists and application of checklists, see GBIF Checklist Datasets and Data Gaps.

There are fewer required fields for checklist datasets compared to other dataset classes (Table 4). As noted, higher classifications (e.g. kingdom) are helpful to include in the data to ensure taxa are not misassigned to the wrong name in the taxonomic backbone.

Table 1. Terms with freshwater-specific definitions, examples, and comments for fields GBIF requires or recommends for checklist datasets.

Term	Definition	Example(s)	Status	Comment
term:dwc[taxonID]	A unique identifier for the taxon; may be a global unique identifier or an identifier specific to the dataset.	8fa58e08-08de-4ac1-b69c-1235340b7001, 32567, ID-fwe-32567	Required	Ideally, the taxonID is a persistent global unique identifier. As a minimum requirement, it has to be unique within the published dataset.
term:dwc[scientificName]	The full scientific name of the organism, to the most precise taxonomic rank that is possible to supply, and including authorship and year of the name where applicable/known	Adicella cremisa Malicky, 1972 (genus + specificEpithet + scientificNameAuthorship)	Required	Names should be compliant to the most recent nomenclatural code. This term should not contain identification qualifications (e.g. cf.), which should instead be supplied in the identificationQualifier term. Ideally, the name supplied is at species level or below. Not permitted are, e.g. working names ("Adicella sp.4"), common names ("creamy caddisfly"), or names containing identification qualifiers ("Adicella cf. cremisa").
term:dwc[taxonRank]	Taxonomic rank of the most most precise taxonomic level provided in term:dwc[scientificName]	One of kingdom, phylum, class, order, family, subfamily, genus, species, subspecies, varietas, forma	Required	Recommended best practice is to use a controlled vocabulary.
term:dwc[kingdom]	Full scientific name of the kingdom in which the taxon is classified.	One of Animalia, Plantae, Fungi, Protista, Monera	Recommended	Inclusion of kingdom helps to ensure taxa are not misassigned to the wrong taxonomic name in GBIF.
term:dwc[parentNameUsageID]	The taxonID of the next available higher-ranked (parent) entry within the checklist dataset, if higher taxon names are supplied as separate entries in the list	2704173 (GBIF), tsn:41074 (ITIS) etc.	Recommended	This supports the representation of the dataset as a hierarchy, e.g. for the publication of a taxonomy. For Darwin Core Archives, the related record should be present locally in the same archive.
term:dwc[acceptedNameUsageID]	Within the record of a synonym, the taxonID of the accepted taxon name entry within the checklist dataset, if both synonyms and accepted names are supplied.	2704179 (GBIF), tsn:41107 (ITIS), etc.	Recommended	This supports the representation of synonymy for a taxonomic dataset. For Darwin Core Archives the related record should be present locally in the same archive.

Occurrence datasets

Occurrence datasets provide information about observations of taxa and the locations where they were found (Table 5). Although only coarse location information is required, the recommended best practice is to always provide coordinates (term:dwc[decimalLatitude] and term:dwc[decimalLongitude] in decimal degrees), a term:dwc[geodeticDatum] which will automatically be interpreted to WGS84 when data are published to GBIF, and a measure of the uncertainty around the coordinates (term:dwc[coordinateUncertaintyInMeters]).

Occurrence datasets can be provided as presence data (e.g. a “1” for a site where the taxon was observed) or as counts in the field term:dwc[individualCount] (Table 5). Counts in this case refer to situations where there is not an effort to estimate the total abundance of the taxon (e.g. by collecting a sample), but instead, numbers of individuals are recorded (tallied) as individuals are encountered. This could include point counts (e.g. in bird surveys, when an observer counts the number of individuals of each species that is viewed or heard) or opportunistic observations. When an effort is made to estimate, for example, abundance, density or biomass as part of targeted or assemblage sampling, these measures should be recorded in the field term:dwc[organismQuantity] with units recorded in term:dwc[organismQuantityType] (Table 5). Ideally, such occurrence datasets should also be accompanied by sampling-event datasets to provide details on sampling methods. Finally, if effort has been put into recording true absences (e.g. through systematic and/or extensive sampling procedures), then presence or absence can be recorded in the field term:dwc[occurrenceStatus] (Table 5). These distinctions will facilitate meta-analysis of data collected in a similar manner or will allow for data to be adjusted as needed for analysis (e.g. all data converted to presence data).

Table 2. Terms with freshwater-specific definitions, examples, and comments for fields GBIF requires or recommends for occurrence datasets

Term	Definition	Example(s)	Status	Comment
term:dwc[occurrenceID]	Identifier for the occurrence; in the absence of a persistent global unique identifier, construct one from a combination of identifiers in the record that will most closely make the occurrenceID globally unique	AT:BOKU:DAN_0003:8755 (country:institutionCode: sampleCode:speciesID)	Required	This should be a unique identifier for the occurrence, allowing the same occurrence to be recognised across dataset versions as well as through data downloads and use. At the very least the identifier should be unique to the dataset, and ideally a globally unique identifier.
term:dwc[basisOfRecord]	The specific nature (type) of the individual data record	One of PreservedSpecimen, FossilSpecimen, HumanObservation	Required	Use "PreservedSpecimen", if the species is preserved somewhere, so that checking back is possible. "FossilSpecimen" refers to fossil samples from, e.g. sediment cores. "HumanObservation" refers to observations of living organisms that were not collected (e.g. catch and release or point count).
term:dwc[scientificName]	The full scientific name of the organism, to the most precise taxonomic rank that is possible to supply, and including authorship and year of the name where applicable/known	Adicella cremisa Malicky, 1972 (genus + specificEpithet + scientificNameAuthorship)	Required	Names should be compliant to the most recent nomenclatural code (see ICZN Code). This term should not contain identification qualifications (e.g. cf.), which should instead be supplied in the term:dwc[identificationQualifier] term. Ideally, the name supplied is at species level or below. Not permitted are, e.g. working names ("Adicella sp.4"), common names ("creamy caddisfly"), or names containing identification qualifiers ("Adicella cf. cremisa").
term:dwc[eventDate]	The date or interval during which an event occurred/the occurrence record was collected; not suitable for a time in a geological context (e.g. 5000 BP)	1809-02-12 (12 February 1809)	Required, though year, month, day, or other terms could be used instead	Use the following format: yyyy-mm-dd four-digit year-month-day. Please make sure to provide separate columns for year, month and day as well. Note that the time should not be included as part of this element, please use term:dwc[eventTime] instead where required.
term:dwc[eventID] (if linked to an event)	Identifier for the set of information associated with an event (something that occurs at a place and time) allowing to link individual occurrences to a specific event; may be a global unique identifier or an identifier specific to the dataset.	AT:BOKU:DAN_0003:MHS (country:institutionCode: sampleCode:method)	Required, if event dataset is available	If occurrence has an event dataset (e.g. methods metadata describing the sampling event during which the occurrence was recorded), provide the identifier for the information associated with the event. This can e.g. be entered as the term:dwc[occurrenceID] without the species code and with the method added.
term:dwc[taxonRank]	Taxonomic rank of the most most precise taxonomic level provided in term:dwc[scientificName].	One of kingdom, phylum, class, order, family, subfamily, genus, species, subspecies, varietas, forma	Recommended	Recommended best practice is to use a controlled vocabulary.
term:dwc[kingdom]	Full scientific name of the kingdom in which the taxon is classified.	One of Animalia, Plantae, Fungi, Protista, Monera	Recommended	Inclusion of kingdom helps to ensure taxa are not misassigned to the wrong taxonomic name in GBIF.
term:dwc[decimalLatitude]	Geographic latitude (in decimal degrees, using the spatial reference system given in term:dwc[geodeticDatum]) of the geographic center of a location.	-41.0983423	Recommended	Positive values are north of the Equator, negative values are south of it. Legal values lie between -90 and 90, inclusive. For freshwater datasets, best practice is that coordinates are mandatory, although the GBIF data description indicates that this can be coarse (e.g. country).
term:dwc[decimalLongitude]	Geographic longitude (in decimal degrees, using the spatial reference system given in term:dwc[geodeticDatum]) of the geographic center of a location.	-121.1761111	Recommended	Positive values are east of the Greenwich Meridian, negative values are west of it. Legal values lie between -180 and 180, inclusive. For freshwater datasets, best practice is that coordinates are mandatory, although the GBIF data description indicates that this can be coarse (e.g. country).
term:dwc[geodeticDatum]	The coordinate system and set of reference points upon which the geographic coordinates given in term:dwc[decimalLatitude] and term:dwc[decimalLongitude] are based.	EPSG:4326, WGS84, unknown	Recommended	Recommended best practice is to use the EPSG code of the spatial reference system, if known. If no geodetic datum is specified, GBIF’s indexing process assumes "WGS84".
coordinate​Uncertainty​InMeters	The horizontal distance (in meters) from the given term:dwc[decimalLatitude] and term:dwc[decimalLongitude] describing the smallest circle containing the whole of the location.	30 (reasonable lower limit on or after 2000-05-01 of a GPS reading under good conditions if the actual precision was not recorded at the time) 100 (reasonable lower limit before 2000-05-01 of a GPS reading under good conditions if the actual precision was not recorded at the time)	Recommended	Leave the value empty if the uncertainty is unknown, cannot be estimated, or is not applicable (because there are no coordinates). Zero is not a valid value for this term. Uncertainty can be used to specify the radius of a sampling area around a central point provided in decimalLatitude and decimalLongitude.
term:dwc[countryCode]	Standard code for the country in which the location occurs.	AR (Argentina) SV (El Salvador)	Recommended	Recommended best practice is to use ISO 3166-1-alpha-2 country codes. Recommended best practice is to leave this field blank if the location spans multiple entities at this administrative level.
term:dwc[individualCount]	Number of individuals at the time of the occurrence, indicated as presence or as a count.	1	Recommended	If you have presence data, please indicate "1" here. If a dataset derives from observed counts (e.g. point counts or opportunistic observations of individuals as encountered), enter the counts here. As these are only counts (not density or biomass), there are no units. If the dataset derives from efforts to estimate abundance of particular taxa (targeted sampling) or composition/abundance of different taxa in the assemblage (assemblage sampling), please enter abundance under organismQuantity with "individuals" entered under organismQuantityType. If the dataset derives from standard protocols for measuring and monitoring biodiversity or abundance, please consider to use the sampling-event dataset.
term:dwc[organismQuantity]	Number or enumeration value for the quantity of organisms as abundance, density, or biomass.	27 (organismQuantity) with "individuals per m²" (organismQuantityType) 12.5 (organismQuantity) with "% biomass" (organismQuantityType) 150 (organismQuantitiy) with "mg dry mass" (organismQuantityType) 800 (organismQuantity) with "individuals" (organismQuantityType)	Recommended	An entry for organismQuantity must have a corresponding term:dwc[organismQuantityType]. If you have abundance data, fill in the number individuals and add unit for it in term:dwc[organismQuantityType]. If the dataset derives from efforts to estimate abundance of particular taxa (targeted sampling) or composition/abundance of different taxa in the assemblage (assemblage sampling), please enter abundance here with "individuals" entered under organismQuantityType. If the dataset derives from standard protocols for measuring and monitoring biodiversity or abundance, please consider to use the sampling-event dataset.
term:dwc[organismQuantityType]	Type of quantification system used for the quantity of organisms	"27" (organismQuantity) with individuals per m² (organismQuantityType) "12.5" (organismQuantity) with % biomass (organismQuantityType) "150" (organismQuantitiy) with mg dry mass (organismQuantityType) "800" (organismQuantity) with individuals (organismQuantityType)	Recommended	A organismQuantityType must have a corresponding organismQuantity. If you have abundance data, fill in the number individuals in organismQuantity and add unit for it here.
term:dwc[occurrenceStatus ]	Statement about the presence or absence of a taxon at a location	One of present or absent	Share if available	For occurrences, the default vocabulary is recommended to consist of present and absent, but the value 'absent' should be used here to record that the sampling did not detect the species, i.e. effort was put into trying to detect the species and it was not detected. For example, if using targeted sampling to estimate species range, non-detections can be identifed here and used to estimate species range using a chosen model for inference, or if a species was previously noted at this location but was not there at the time of the sampling (potentially indicating species loss), then please indicate "absent" here.

Sampling-event datasets

Sampling-event data are structured and systematic surveys (i.e. periodical or singular surveys, routine or one-time environmental monitoring) that must include metadata describing sampling methods (Table 6). Please note that each event dataset consists of two files: the sampling-event dataset and the associated occurrence dataset. The associated occurrence dataset looks like the one in §2.1.2. but needs to be amended with the term:dwc[eventID] (mandatory; identifying the event and linking the two datasets) and the term:dwc[occurrenceStatus] (recommended to indicate whether a taxon was present or not detected at a site).

Sampling methods are described in the sampling-event dataset with the field term:dwc[samplingProtocol], which provides a name/link to a specific protocol and/or description of the protocol (Table 6). The recommended best practice is to have a separate event for each sampling method used. In addition to describing the protocol, the field term:dwc[sampleSizeValue] and term:dwc[sampleSizeUnit] can be used to indicate the spatial or temporal extent of sampling for the described sampling event, as a measure of sampling effort for each event. In addition, the field term:dwc[samplingEffort] can be used to record the total effort spent on the event, for example, when there were multiple nets, multiple microhabitats sampled, or multiple periods of time over which sampling occurred. Additional details about sampling methods are recommended to be included in the freshwater DwC extensions described in §3.1.

Table 3. Terms with freshwater-specific definitions, examples, and comments for fields GBIF requires or recommends for sampling-event datasets

Term	Definition	Example(s)	Status	Comment
term:dwc[eventID]	Identifier for the set of information associated with an event (something that occurs at a place and time) allowing to link individual occurrences to a specific event; may be a global unique identifier or an identifier specific to the dataset	AT:BOKU:DAN_0003:MHS1 (country:institutionCode: sampleCode:method)	Required	If occurrence has an event dataset (e.g. methods metadata describing the sampling event during which the occurrence was recorded), provide the identifier for the information associated with the event. This can e.g. be entered as the term:dwc[occurrenceID] without the species code and with the method added.
term:dwc[eventDate]	The date or interval during which an event occurred/the occurrence record was collected; not suitable for a time in a geological context	1809-02-12 (12 February 1809)	Required, though year, month, day, or other terms could be used instead	Use the following format: yyyy-mm-dd four-digit year-month-day. Please make sure to provide separate columns for year, month and day as well. Note that the time should not be included as part of this element, please use term:dwc[eventTime] instead where required.
term:dwc[samplingProtocol]	Names of, references to, or descriptions of the methods or protocols used during an event	Environment Canada. (2012). Canadian Aquatic Biomonitoring Network Field Manual - Wadeable Streams. Available at http://publications.gc.ca/pub?id=9.696248&sl=0 SS–EN 27 828, Water quality - Methods for biological sampling - Guidance on the handnet sampling of benthic macroinvertebrates net fishing and full/partly following NS-EN 14757	Required	Recommended best practice is describe an event with no more than one sampling protocol/method, and have a separate event for each method used, with occurrences separated by method. If a more detailed description of the method or protocol exists, providing a reference is strongly encouraged.
term:dwc[sampleSizeValue]	Numeric value for a measurement of the size (time duration, length, area, or volume) of an individual sample in the sampling event	5 (sampleSizeValue with "metre" as term:dwc[sampleSizeUnit])	Required	A sampleSizeValue must have a corresponding term:dwc[sampleSizeUnit]. The sample size can relate to time duration, a spatial length (e.g. of a trawl), an area or a volume.
term:dwc[sampleSizeUnit]	The unit of measurement of the size (time duration, length, area, or volume) of a sample in a sampling event	minute, metre, square metre	Required	A sampleSizeUnit must have a corresponding term:dwc[sampleSizeValue]. Recommended best practice is to use a controlled vocabulary for the sampleSizeUnit.
term:dwc[parentEventID]	Identifier for the broader event that groups this and potentially other events; may be a global unique identifier or an identifier specific to the dataset	A1 (parentEventID to identify a transect of samples with its own eventIDs: "A1:1", "A1:2"), AT:BOKU:DAN (country:institutionCode:projectCode)	Recommended	Used in situations where the event is part of an event series. In order to be able to reference a parent event, this event needs to be specified as a separate entry, typically within the same dataset, carrying its own term:dwc[eventID]. Refer to the eventID of the parent event in the sample event record to specify the relationship between the two entries.
term:dwc[samplingEffort]	Measure for the amount of effort expended during an event	40 trap-nights, 10 observer-hours	Recommended	Used to provide evidence of the rigour of the sampling event, e.g. the number of people involved, total area sampled (summed across different sampled microhabitats), or the total number of hours spent on the event (e.g. net set time summed across multiple nets). There is no controlled vocabulary, but the recommendation is to keep this information brief and factual, giving users enough information to compare between sampling events.
term:dwc[locationID]	Identifier that links to a set of data describing the sample event location, if available; may be a global unique identifier or an identifier specific to the dataset	http://www.geonames.org/10793757/dnb-6.html	Recommended	If such a reference cannot be meaningfully supplied, consider supplying more location details, e.g. through use of the data elements term:dwc[locality], term:dwc[minimumElevationInMeters], term:dwc[minimumDepthInMeters], term:dwc[stateProvince], term:dwc[locationRemarks] etc.
term:dwc[decimalLatitude]	Geographic latitude (in decimal degrees, using the spatial reference system given in term:dwc[geodeticDatum]) of the geographic center of a location	-41.0983423	Recommended	Positive values are north of the Equator, negative values are south of it. Legal values lie between -90 and 90, inclusive. Note that a sample event that spans an area rather than a point location should additionally supply the term:dwc[coordinateUncertaintyInMeters] to specify the approximate extension of the area.
term:dwc[decimalLongitude]	Geographic longitude (in decimal degrees, using the spatial reference system given in term:dwc[geodeticDatum]) of the geographic center of a location	-121.1761111	Recommended	Positive values are east of the Greenwich Meridian, negative values are west of it. Legal values lie between -180 and 180, inclusive. Note that a sample event that spans an area rather than a point location should additionally supply the term:dwc[coordinateUncertaintyInMeters] to specify the approximate extension of the area.
term:dwc[geodeticDatum]	The coordinate system and set of reference points upon which the geographic coordinates given in term:dwc[decimalLatitude] and term:dwc[decimalLongitude] are based	EPSG:4326, WGS84, unknown	Recommended	Recommended best practice is to use the EPSG code of the spatial reference system, if known. If no geodetic datum is specified, GBIF’s indexing process assumes "WGS84".
coordinate​Uncertainty​InMeters	The horizontal distance (in meters) from the given term:dwc[decimalLatitude] and term:dwc[decimalLongitude] describing the smallest circle containing the whole of the location	30 (reasonable lower limit on or after 2000-05-01 of a GPS reading under good conditions if the actual precision was not recorded at the time) 100 (reasonable lower limit before 2000-05-01 of a GPS reading under good conditions if the actual precision was not recorded at the time)	Share if available	Leave the value empty if the uncertainty is unknown, cannot be estimated, or is not applicable (because there are no coordinates). Zero is not a valid value for this term. Uncertainty can be used to specify the radius of a sampling area around a central point provided in term:dwc[decimalLatitude] and term:dwc[decimalLongitude].
term:dwc[footprintWKT]	An area description, specifying the location of the sample event in well-known text (WKT) markup language	POLYGON ((10 20, 11 20, 11 21, 10 21, 10 20)) (a one-degree bounding box with opposite corners at longitude=10, latitude=20 and longitude=11, latitude=21)	Recommended	A WKT representation of the shape (footprint, geometry) that defines the location. This differs from the point-radius representation that is combined from the elements term:dwc[decimalLatitude], term:dwc[decimalLongitude] and term:dwc[coordinateUncertaintyInMeters] in that it can define shapes that are not circles. Note that it is possible to supply both a point-radius and a footprintWKT location for the same sample event.
term:dwc[footprintSRS]	The ellipsoid, geodetic datum, or spatial reference system (SRS) upon which the geometry given in term:dwc[footprintWKT] is based	EPSG:4326, unknown	Recommended	Recommended best practice is to use the EPSG code of the SRS, if known. If none of these is known, use the value "unknown". It is also permitted to provide the SRS in Well-Known-Text, especially if no EPSG code provides the necessary values for the attributes of the SRS. Do not use this term to describe the SRS of the term:dwc[decimalLatitude] and term:dwc[decimalLongitude], nor of any verbatim coordinates - use the term:dwc[geodeticDatum] and term:dwc[verbatimSRS] instead.
term:dwc[countryCode]	Standard code for the country in which the location occurs	AR (Argentina) SV (El Salvador)	Recommended	Recommended best practice is to use ISO 3166-1-alpha-2 country codes. Recommended best practice is to leave this field blank if the location spans multiple entities at this administrative level.

Specific requirements for publishing freshwater datasets (freshwater amendments)

Table 7 lists the [DwC] fields that are useful to include in freshwater datasets to support large-scale data compilation and analysis. In some cases, fields should be included in an [extension]. Extensions offer a way to include additional information and to provide multiple measurements (e.g., different habitat variables) to link to a single event. Freshwater amendment fields are tagged as:

• Freshwater required: as an addition to the GBIF required fields, we recommend required fields for freshwater samples

• Freshwater recommended: data that are useful to be reported

• Freshwater share if relevant: data that should be reported, but that are only relevant to particular organism groups or habitats (as indicated)

We provide examples for the content of the fields, and in some cases, the full range of controlled values to choose from.

The freshwater amendments include general fields describing the site where the observation was made, such as the water body name, a description of the location, and the elevation (Table 7). The organism group should be included for all GBIF dataset classes, and this information can be captured in the Humboldt Ecological Inventory extension in the field targetTaxonomicScope, which is designed to indicate the taxonomic group that was targeted during sampling. Organism groups should be listed in this field using the assemblage categories described in Table 1.

Current extensions do not have fields that correspond to the freshwater data categories (§1.2.2), either for the type of observation or type of contribution. This information can be captured in the dynamic properties field until specific fields are created.

There are fields recommended for freshwater data that describe the sampled environment, such as the depth of sampling and any abiotic measurements taken in the field, including temperature, pH, and dissolved oxygen (Table 7). Physical and chemical measurements from the habitat should be included in the Extended Measurement or Facts extension to allow multiple measurements to be linked to a single Event dataset.

Other freshwater-specific habitat descriptions, including the [biome], [ecosystem functional group], [lake zone], [river mesohabitat], and [microhabitat] (e.g. sand, gravel, cobble), can be entered in the term:dwc[habitat] field. This is a multivalue, free-text field, and a proposed structure for this information is provided in Table 7. Although the ultimate goal is to create specific fields for these terms, this field represents the currently available option for recording the information.

Further details about the event time and date are also recommended for inclusion (Table 7). For example, it is recommended that data providers include year, month and day as separate columns in their dataset. This avoids ambiguities that might occur due to regional differences in how year, month, and day are combined into a single field (e.g. confusion of month and day). Furthermore, it is important that all years be entered as four-digit numbers, as historical data (e.g. early 1900s) might be present in GBIF because of digitizing of old records, and full four-digit years ensure that dates are not mishandled.

Additional fields for observation data include the sex and life stage, both of which are conditional based on the organism group (for example, sex can be determined and is relevant for fish, mammals, birds, and decapods; life stage can be determined and is relevant for copepods, [benthic] macroinvertebrates, fish and birds). The DwC term lifeStage has a controlled vocabulary (see GBIF vocabulary - LifeStage for full list), and this vocabulary does not include all terms that are relevant for freshwater. For example, young of year is not part of the controlled vocabulary, and it is recommended that juvenile be used instead. Similarly, juvenile can be used instead of copepodite, and immature can be used instead of early instar. Additional fields provide details on the identification of the observed taxon, such as references and verification status.

Table 4. Terms, definitions, examples, and comments recommended for inclusion with freshwater datasets. The dataset in which each field should be included (metadata, occurrence or event) is indicated, as is whether fields are required, recommended, or share if relevant on particular organism groups (more information on the specific fields).

Term	Definition	Example(s)	Status	Comment	Inclusion
term:dwc[rightsHolder]	A person or organisation owning or managing the rights over the resource	BOKU University (University of Natural Resources and Life Sciences, BOKU Vienna)	Recommended		Metadata
term:dwc[institutionCode]	Name or acronym of the institution having custody of the dataset or record	BOKU (University of Natural Resources and Life Sciences, BOKU Vienna) UNB (University New Brunswick)	Recommended		Metadata
term:dwc[collectionID]	Identifier for the collection or dataset from which the record was derived	urn:lsid:biocol.org: col:34818, https://www.gbif.org/grscicoll/collection/fbd3ed74-5a21-4e01-b86a-33d36f032d9c	Recommended	For physical specimens, the recommended best practice is to use a globally unique and resolvable identifier from a collections registry such as the Global Registry of Scientific Collections.	Occurrence
term:dwc[informationWithheld]	Additional information that exists, but that has not been shared in the given record	location information not given for endangered species	Recommended	A note on possible information that was intentionally not included into the dataset.	Occurrence
term:dwc[dynamicProperties]	List of additional measurements, facts, characteristics, or assertions about the record, meant to provide a mechanism for structure content	type of observation:opportunistic observation, type of contribution:community-based research data	Recommended	Recommended best practice is to use a "key:value" encoding schema for a data interchange format (such as JSON). Please use this field for indicating the type of observation (opportunistic observation, targeted sampling, or assemblage sampling data) and type of contribution (professional, community-based research, or citizen science data).	Occurrence
term:dwc[habitat]	A description of the habitat in which the event occurred	biome:river, ecosystem functional group:lowland river, lake zone:littoral, river mesohabitat:riffle, microhabitat:sand; for biome and ecosystem functional group, use classifications in the IUCN Global Ecosystem Typology (https://global-ecosystems.org/page/typology); for lake zone use one of: "littoral", "sub-littoral", "pelagic", "profundal"; for river mesohabitat use one of: "riffle", "run", "pool"	Required	Recommended best practice is to use a "key:value" encoding schema for a data interchange format (such as JSON). Please use this field for adding information on e.g. biome, ecosystem functional group, lake zone, river mesohabitat, or microhabitat until specific fields have been created for these categories.	Occurrence, Event
target​Taxonomic​Scope	The taxonomic group(s) targeted for sampling during the dwc:Event.	One of fungi,microbes,benthic algae,phytoplankton,macrophytes,zooplankton,benthic macroinvertebrates,decapods,fish,amphibians,reptiles,birds,mammals	Required	For freshwater, the targeted taxonomic group should be at the level of biologically- and ecologically-similar organisms that are generally grouped together and described as an assemblage. Use broader groups as listed here even if a subset of the group was the focus. For example, use zooplankton even if only cladocerans were sampled. Benthic algae refers to benthic samples of diatoms and other algae, which may include planktonic individuals that have settled.	Checklist, Occurrence (map to Humboldt Ecological Inventory extension)
term:dwc[recordedBy]	A list (concatenated and separated) of names of people, groups or organizations responsible for recording the original occurrence; the primary collector or observer should be listed first	Jen Lento | Astrid Schmidt-Kloiber	Recommended	Recommended best practice is to separate the values in a list with space vertical bar space, or post (|).	Occurrence
term:dwc[recordedByID]	A list (concatenated and separated) of the globally unique identifier for the person, people, groups, or organizations responsible for recording the original term:dwc[Occurrence].	https://orcid.org/0000-0002-8098-4825 | https://orcid.org/0000-0001-8839-5913	Recommended	Recommended best practice is to separate the values in a list with space vertical bar space, or post (|). The primary collector or observer should be listed first.	Occurrence
term:dwc[sex]	The sex of the individual(s) represented in the occurrence.	One of female or male or indeterminate	Share if relevant (based on the organism group (Decapoda, fish, mammals, birds))		Occurrence
term:dwc[lifeStage]	The age class or life stage of the organism(s) at the time the occurrence was recorded	One of egg, larva, pupa, adult, subadult, juvenile, nymph, immature, nauplius	Share if relevant (based on the organism group (benthic invertebrates, zooplankton - Copepoda, fish, birds))	Controlled vocabulary does not include all terms that are relevant for freshwater. For example, use juvenile instead of young of year or copepodite, and use immature instead of early instar.	Occurrence
term:dwc[occurrenceRemarks]	Comments or notes about the occurrence	found dead outside of the water	Recommended		Occurrence
term:dwc[eventType]	The nature of the event	sample, observation, bioblitz, expedition, survey, "project`, site visit, biotic interaction	Recommended		Event
term:dwc[eventTime]	The time or interval during which an event occurred	14:07-0600 (2:07pm in the time zone six hours earlier than UTC) 13:00:00Z/15:30:00Z (the interval between 1pm UTC and 3:30pm UTC)	Share if available	Recommended best practice is to use a time of day that conforms to ISO 8601-1:2019. Please also add the time zone in relation to UTC.	Event
term:dwc[year]	Four-digit year in which the event occurred	2008	Share if available	Please fill this column additionally to the term:dwc[eventDate].	Occurrence Event
term:dwc[month]	Month in which the event occurred	01 (January), 10 (October)	Share if available	Please fill this column additionally to the term:dwc[eventDate].	Occurrence Event
term:dwc[day]	Day of the month on which the event occurred	09, 28	Share if available	Please fill this column additionally to the term:dwc[eventDate].	Occurrence Event
term:dwc[verbatimEventDate]	The verbatim original representation of the date and time information for an event	spring 1900, Marzo 2002	Share if available	Please keep your original date/time stamp here (if applicable).	Occurrence Event
term:dwc[eventRemarks]	Comments or notes about the event	After the recent rains the river is nearly at flood stage.	Share if available		Event
term:dwc[waterBody]	Name of the water body in which the location occurs	River Danube, Lake Constance	Required	Recommended best practice is to use a controlled vocabulary such as the Getty Thesaurus of Geographic Names.	Occurrence
term:dwc[locality]	The specific description of the place, providing regional context to the observation	25 km downstream Vienna	Recommended	Less specific geographic information can be provided in other geographic terms (term:dwc[higherGeography], term:dwc[continent], term:dwc[country], term:dwc[stateProvince], term:dwc[county], term:dwc[municipality], term:dwc[waterBody], term:dwc[island], term:dwc[islandGroup].	Occurrence
term:dwc[minimumElevationInMeters]	The lower limit of the range of elevation (altitude, usually above sea level), in metres	100	Recommended	If sampling was done at one altitude only (e.g. no range), enter the actual altitude at which your sample was taken in both this field and in term:dwc[maximumElevationInMeters].	Occurrence
term:dwc[maximumElevationInMeters]	The upper limit of the range of elevation (altitude, usually above sea level), in metres	200	Share if available	If sampling was done at one altitude only (e.g. no range), enter the actual altitude at which your sample was taken in this field and in term:dwc[minimumElevationInMeters].	Occurrence
term:dwc[verbatimElevation]	The original description of the elevation (altitude, usually above sea level) of the location	100-200 m	Share if available		Occurrence
minimumDepth​InMeters	The lesser depth of a range of depth below the local surface, in metres	0.5	Recommended	If sampling took place over a range of depths (e.g. depth-integrated sample or composite sample from water column), enter the minimum depth here and the maximum depth of the range in term:dwc[maxiumDepthInMeters]. If sampling was depth-specific (e.g. at one single depth), enter the actual depth in which your sample was taken in this field and in term:dwc[maximumDepthInMeters].	Occurrence
maximumDepth​InMeters	The greater depth of a range of depth below the local surface, in metres	1	Share if available	If sampling took place over a range of depths (e.g. depth-integrated sample or composite sample from water column), enter the minimum depth here and the maximum depth of the range in term:dwc[maxiumDepthInMeters]. If sampling was depth-specific (e.g. at one single depth), enter the actual depth in which your sample was taken in this field and in term:dwc[minimumDepthInMeters].	Occurrence
term:dwc[verbatimDepth]	The original description of the depth below the local surface	0.5 - 1 m	Share if available		Occurrence
identification​Qualifier	A brief phrase or a standard term ("cf.", "aff.") to express the determiner’s doubts about the identification	cf.	Recommended	Can be used to add doubts, but it is recommend to only report "safe" records	Occurrence
term:dwc[identifiedBy]	A name or a list (concatenated and separated) of names of people, groups, or organizations who assigned the taxon to the subject	Hans Malicky, Jen Lento | Astrid Schmidt-Kloiber	Recommended	Recommended best practice is to separate the values in a list with space vertical bar space, or post (|).	Occurrence
term:dwc[identifiedByID]	A list (concatenated and separated) of the globally unique identifier for the person, people, groups, or organizations responsible for assigning the term:dwc[Taxon] to the subject.	https://orcid.org/0000-0002-8098-4825 | https://orcid.org/0000-0001-8839-5913	Recommended	Recommended best practice is to separate the values in a list with space vertical bar space, or post (|).	Occurrence
identification​References	A reference or a list (concatenated and separated) of references (publication, global unique identifier, URI) used in the identification	Malicky, H. 2004 (2nd edtion): Atlas of European Trichoptera. Springer. 1-341.	Recommended	Recommended best practice is to separate the values in a list with space vertical bar space, or post (|). Add a DOI if available.	Occurrence
identification​Verification​Status	A categorical indicator of the extent to which the taxonomic identification has been verified to be correct	one of verified, unverified, requires verification	Recommended		Occurrence
term:dwc[identificationRemarks]	Comments or notes about the identification	Verified by H. Malicky	Share if available (based on term:dwc[identificationVerificationStatus])	Use this field to indicate the person who has verified the identification. You can also use it for describing difficulties with the identification.	Occurrence
term:dwc[class]	The full scientific name of the class in which the taxon is classified	Mammalia, Insecta	Share if available	Inclusion of class helps to ensure taxa are not misassigned to the wrong taxonomic name in GBIF.	Occurrence
term:dwc[vernacularName]	Common or vernacular name	Wassergeistchen, yellow-bellied toad	Recommended		Occurrence
term:dwc[measurementType]	The nature of the measurement, fact, characteristic, or assertion	temperature, pH	Share if available	This field is for additional measurements in the field, e.g. abiotic data. A measurementType must have a corresponding term:dwc[measurementValue] and term:dwc[measurementUnit].	Event (map to Extended Measurement or Facts extension)
term:dwc[measurementValue]	The value of the measurement, fact, characteristic, or assertion	-1, 7.1	Share if available	This field is for additional measurements in the field, e.g. abiotic data. A term:dwc[measurementType] must have a corresponding measurementValue and term:dwc[measurementUnit].	Event (map to Extended Measurement or Facts extension)
term:dwc[measurementUnit]	The unit associated with the term:dwc[measurementValue]	°C, g, %	Share if available	This field is for additional measurements in the field, e.g. abiotic data. A term:dwc[measurementType] must have a corresponding term:dwc[measurementValue] and measurementUnit.	Event (map to Extended Measurement or Facts extension)
term:dwc[measurementMethod]	A description of or reference to (publication, URI) the method or protocol used to determine the measurement, fact, characteristic, or assertion	water thermometer, pH meter	Share if available		Event (map to Extended Measurement or Facts extension)
term:dwc[measurementRemarks]	Comments or notes accompanying the term:dwc[measurementType]	water partly frozen	Share if available		Event (map to Extended Measurement or Facts extension)