Jellyfish in Hong Kong: a citizen science dataset

Study Extent

Hong Kong Special Administrative Region (SAR) is located on the southern coast of mainland China at 22.3193° N, 114.1694° E, at the northern end of the South China Sea. Its marine boundary contains 1,651 km² of water and a rich marine biodiversity despite being only 0.03% of Chinese waters. This study has been running since early 2021 and is a continuous year-round collection of observations of jellyfish.

Sampling

Participants submit any observation of an individual jellyfish or group of jellyfish, or multiple observations of different jellyfish at their own discretion. Additionally, observations of the absence of jellyfish can be reported through the HKJP website or social media, and these can be captured in GBIF. Jellyfish are encountered opportunistically by participants as they conduct normal daily activities. Observations typically increase during high bloom times in April and May following a seasonal pattern. Sightings are also reported following project promotion through social (Facebook, Instagram) or traditional media (radio, newspaper). Periodic HKJP newsletters by email and journal posts on iNaturalist are conducted to maintain observer interest and promote project awareness. Each observation from the HKJP website includes fields describing their: (i) taxonomy to the lowest level possible (kingdom, phylum, class, order, family, genus, species); (ii) location in observer’s own words or geolocation (latitude, longitude); (iii) date of observation (dd/mm/yyyy); (iv) time of observation (24hr); (v) how many jellyfish were seen (No jellyfish seen, 1, <10, 10-100, 100-500, 500-1000, not recorded/don’t know); (vi) space between individuals (10cm, <1m, 1-5m, 5-10m, 10-20m, >20m, not recorded/don’t know); (vii) individuals per square meter (<10, 10-100, 100-500, >500, not recorded/don’t know); (viii) observation made while (fishing, sailing, diving/snorkeling/swimming, on a boat/ferry, walking along the coast, kayaking/SUP, other); (ix) photograph(s) and/or video of jellyfish. For observations that came through social media we attempted to obtain as much of the above information as possible, though greater gaps remain in this dataset. Observations from the iNaturalist project include fields describing: (i) user id; (ii) date of observation (dd/mm/yyyy); (iii) time of observation (24hr); (iv) URL of observation; (v) image URL; (vi) place guess; (vii) latitude of the observation; (viii) longitude of the observation; (ix) species guess; (x) the scientific name to the lowest level possible (kingdom, phylum, class, order, family, genus, species); (xi) the common name as determined by iNaturalist. The observations data has been compiled into the Darwin Core format with fields including: (i) occurrenceID (ii) basisOfRecord (iii) type (iv) language (v) institutionID (vi) institutionCode (vii) recordedBy (viii) eventDate (ix) eventTime (x) associatedReferences (xi) associatedMedia (xii) type (xiii) locality (xiv) decimalLatitude (xv) decimalLongitude (xvi) geodeticDatum (xvii) country (xviii) stateProvince (xix) vernacularName (xx) scientificName (xxi) acceptedNameUsageID (xxii) taxonRank (xxiii) kingdom.

Quality Control

Observations that did not contain verifiable photographs, non-medusa taxa, or were taken from captivity were eliminated from the dataset. Usable observations were identified to the lowest taxonomic level and verified with reference to the literature; primarily, the World Atlas of Jellyfish (2019), Mayer (1910), Kramp (1961), and other sources as required. Some observations were verified by sampling and DNA analysis done at the Simon F.S. Li Laboratory at The Chinese University of Hong Kong. The dataset is made available in Darwin Core format; 1,021 terms are available for the 2021-2023 datasets. All mandatory fields are present and have undergone validation and screening using the TaiBIF IPT, before uploading and publishing via the GigaScience Press GBIF page.

Method steps

1. 1) A citizen scientist observes jellyfish (or absence of jellyfish) while swimming, kayaking, or walking the shore, for example. 2) The observer takes a photograph of the jellyfish and uploads it either through the HKJP website or the iNaturalist app on their phone. They note the date, time, location, and species, if known. Additional information like number and density of jellyfish may be optionally provided if there is a large number of them present. 3) For a submission reported through the website, it is reviewed by the HKJP principal investigator for identification verification and if necessary, reference is made to the literature. Confirmation and additional species information is then shared with the observer. If an observation is unable to be identified it is included in the dataset, but the lack of identification is clearly indicated. 4) For a submission reported through iNaturalist, artificial intelligence usually suggests an identification or a category after automatically recording location and time data within the observer’s pre-set parameters. The observer can select the suggested identification or make their own. Anyone on iNaturalist can suggest an identification and when multiple people agree, the identification is considered Research Grade. 5) For a submission reported on social media, the HKJP principal investigator will ask for as much information (time, date, location, etc.) as possible about the observed jellyfish and permission for use. 6) Observation data for all three sources is recorded into an Excel spreadsheet. Website and iNaturalist submissions can be entered in Traditional Chinese, so observations are translated to English for inclusion in the spreadsheet, the language of the HKJP’s principal investigator. 7) The various data sources are harmonized and curated together into one table, which is then converted into Darwin Core Archive standard to be uploaded to GBIF.

Jellyfish as defined in Brotz et al. (2012) as "gelatinous zooplankton that include medusae of the phylum Cnidaria (scyphomedusae, hydromedusae, cubomedusae, and siphonophores) and planktonic members of the phylum Ctenophora." All observations were identified to the lowest taxonomic level possible, typically genus or species level.

1. Cnidaria
   rank: phylum
2. Ctenophora
   rank: phylum

Waters around Hong Kong Special Administrative Region