This dataset contains occurrence records and associated metadata for the zooplankton species Calanus finmarchicus that were compiled from multiple open access databases. A file containing the corresponding background points is provided, along with gridded environmental variables for each season (Jan-Feb-Mar, Apr-May-Jun, Jul-Aug-Sep, Oct-Nov-Dec) and era (1955-1984, 1985-2017) that were assessed in this study. Together these data were used as input files for the MaxEnt ecological niche model within the peer reviewed article: Freer JJ, Daase, M, Tarling GA, (2021) Modelling the biogeographic boundary shift of Calanus finmarchicus reveals drivers of Arctic Atlantification by subarctic zooplankton, Global Change Biology. Finally, an R Markdown document is provided to enable data users to replicate the model optimisation and prediction steps using the input data files within this repository. Funding was provided by: UKRI Natural Environment Research Council (NERC): DIAPOD (NE/P006213/1), NERC and the German Federal Ministry of Education and Research (BMBF): CHASE (NE/R012687/1), Norwegian Research Council: Deep Impact project (300333).

Here, for the first time in the Southern Ocean, this dataset contains the seasonal occurrence of the zooplankton assemblage in the Northeast Scotia Sea using a sediment trap deployed throughout 2018 (P3 observation site, 52.80 degrees S, 40.14 degrees W). Southern Ocean zooplankton provide globally significant ecosystem services through their role in carbon sequestration, nutrient cycling and food webs. The remote and extreme nature of the Southern Ocean creates significant logistical difficulties for studying zooplankton all year round and there is a significant paucity in winter data. Sediment traps are able to sample throughout the year, providing much needed insight into the seasonality of zooplankton in the Southern Ocean. The dataset is accompanied by temperature data at depth 200 m from the CTD instrument mounted on the P3 observation site mooring. Clara Manno was supported by UK Research and Innovation Future Leaders Fellowships project CUPIDO (MR/T020962/1). Work was carried out as part of the Ecosystems programme at the British Antarctic Survey and the Scotia Sea Open Ocean Laboratories (SCOOBIES) sustained observation programme at the British Antarctic Survey in the frame of a Western Core Box-POETS survey cruise (https://www.bas.ac.uk/project/scoobies/).