DOI: 10.5285/a5cbfbe1-6fa6-44cf-96fe-db92c32b69d0
title: Processing and analysis of Arctic Calanus occurrence records from OBIS and GBIF databases

description: This dataset contains quality-controlled georeferenced occurrence records of three Arctic Calanus species (Calanus finmarchicus, C. glacialis and C. hyperboreus), downloaded from the Ocean Biodiversity Information System (OBIS) and the Global Biodiversity Information Facility (GBIF) databases. Records span about 150 years of sampling (1870-2017), are located between 30 and 90 degrees north, and are distributed between the surface and 5000m deep. Physical (bathymetry) and environmental (temperature and sea-ice concentration) parameters are matched to each occurrence record. An html file provides the annotated source code for the data processing, analyses and figures produced for the publication: Freer JJ and Tarling GA (2023) Assessing key influences on the distribution and life-history of Arctic and boreal Calanus: Are online databases up to the challenge? Front. Mar. Sci. 10:908112. This work was funded by DIAPOD (NE/P006213/1) and CHASE (NE/R012687/1) projects as part of the Changing Arctic Ocean Programme, with the former funded by the UKRI Natural Environment Research Council (NERC) and the latter, jointly by NERC and the German Federal Ministry of Education and Research (BMBF). Further support was provided by BIOPOLE National Capability Multicentre Round 2 funding from the Natural Environment Research Council (NE/W004933/1).
description: Data from OBIS were accessed on 12-01-2023 and data from GBIF were accessed on 13-01-2023. To maintain consistency, all encounters were treated as presence only, i.e. no weighting was given to records with information on abundance, biomass or number of individuals and no absence records were included. Raw downloaded data and the contributing dataset citations are provided for both databases (see Section "Related datasets"). Subsequent data processing and cleaning steps are outlined in section "Quality". All cleaned records, regardless of dataset origin, were matched to seafloor bathymetry using a 0.25 x 0.25 decimal degree resolution raster grid (Becker et al., 2009). Cleaned records from OBIS had fields for maximum and minimum collection depth. These data were matched to vertically resolved temperature data from the 2018 World Ocean Atlas (Locarnini et al., 2018) and seasonal sea-ice concentration data from the National Snow and Ice Data Centre (Walsh et al., 2019). Both temperature and sea ice grids had a resolution of 0.25 x 0.25 decimal degrees.
description: All analyses were carried out in R version 4.2.1.
description: Data processing steps carried out on the raw downloaded files are outlined in detail in the html file of annotated source code. In brief, records were excluded if they were erroneously located on land, in the Pacific sector or in the southern hemisphere; were not identified to species level; had missing identifiers for month or year of collection. Metadata fields for "sampling protocol" ad "lifestage" were cleaned by re-categorising entries into a condensed set of inputs. Duplicate records were removed as defined by records that had the following identical identifiers: species, longitude, latitude, year, month, day, minimum and maximum collection depth (OBIS), average collection depth (GBIF), life-stage. Lastly, cleaned OBIS and GBIF data were combined into a single dataset and duplicate occurrences between databases were removed using the same identical identifiers listed above. Records where average sample collection depth was greater than bathymetric depth were flagged and removed when creating appropriate figures.