The dataset contains compiled records of sea ice meiofauna across the Arctic from 23 sources. This work is based on [State of the Arctic Marine Biodiversity Report]( https://www.caff.is/marine/marine-monitoring-publications/state-of-the-arctic-marine-biodiversity-report/431-state-of-the-arctic-marine-biodiversity-report-full-report) (CAFF, 2017), by the Sea Ice Biota Expert Network of the Circumpolar Biodiversity Monitoring Programme (CBMP) of the Conservation of the Arctic Flora and Fauna (CAFF).

**The dataset is compiled in following files**:

- *Meiofauna_data_v2017-12-11.xlsx* contains all data in separate sheets. The information here is from the "Info" tab.

- *Info.csv* contains the same information than listed here.

- *Columns.csv:* Column explanation for datasheets.

- *References.csv*: Reference list for the dataset.

- *Original.csv*: Minimally modified non-transformed original data. Used only as a reference to the original data and in quality checks.Relative Ciliata and Rotifera abundances were transformed to estimated absolute abundances (see "Columns" sheet). Some entries, taxa, and ice-cores were removed due to unclarities.

- *Transformed.csv:* Abundance values transformed to ind/m2 values. Ice-core sections not summed up.

- *Compiled.csv:* Ice-core sections summed up for each ice-core. Used in the SAMB report.

- *Cut10cm.csv:* Bering Sea, Barrow, and N-ICE data. Only bottom 10 cm of ice-cores are included. If all of bottom 10 cm was not available, less than that was included. Used in Fig 3, Fig 4 and Fig 6 in the Ecology & Evolution paper. Subset Sec == "bottom 10 cm" before usage for comparison purposes. Note that Fig 3 and 4 in the paper have been created after excluding all ice-core sections other than "bottom 10 cm".

- *Article.all.csv:* All data (including RAW columns) for the manuscript. Note that GRAND SUM columns are derived from RAW columns (i.e. the dataset contains duplicates). Used in Table 2 in the Ecology & Evolution paper. This is the most comprehensive and checked dataset.

- *Article.groups.csv:* Only GRAND SUM abundance columns for the manuscript. Used in Fig 1, Fig 5 and in some statistical tests in the Ecology & Evolution paper.

- *Article.per.csv:* Percentage data by ice-core for GRAND SUM columns. Used in Fig 7 in the Ecology & Evolution paper.

- *Wholecore.csv:* Data where the entire ice-core was sufficiently sectioned to enable examining depth distribution of taxa within ice-cores. Absolute values.

- *Wholecore.grp.csv:* Same than "Wholecore.csv" but presents percentages for each ice-core by group. Used in Fig 2 in the Ecology & Evolution paper.

If you are in doubt which dataset to pick, **use "Article_all.csv"**. This is the most comprehensive, checked and least summarized dataset.