Haakon Hop

Mikko Vithakari

Bodil A. Bluhm

Philipp Assmy

Michel Poulin

Ilka Peeken

Rolf Gradinger

Igor A. Melnikov

The data sources originated from Arctic and Antarctic Research Institute (AARI), Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI) and Norwegian Polar Institute (NPI) and the processing of the samples vary slightly between the three different institutions. The different procedures are decribed in Hop et al. 2021. In all sample sea-ice protists were identified to the lowest possible taxonomic rank under inverted light microscope. The taxonomic nomenclature has changed considerably within the four decades of data coverage in this study therefore taxa name reported in the original datasets were corrected, updated and unified using a three-step protocol. First, all reported taxa names were passed through the World Register of Marine Species database (WoRMS Editorial Board, 2018) to confirm the validity of a name using the taxize package (Chamberlain and Szöcs, 2013) for 263 R (R Core Team, 2018). Second, the returned taxon names were then validated by protist taxonomy experts within the author team, and when needed, checked against the AlgaeBase database ( http://www.algaebase.org/), which represents more up-to-date classification of protist taxa than WoRM, but is not programmatically available due to copyright restrictions. Finally, the taxon names were manually edited to make the taxonomic ranks across datasets as comparable as possible. Since the taxonomic ranks are not consistent within the compiled dataset, we use the term “taxa” when referring to all sea-ice protists and the term “species” when referring to species level or lower.

CEOS IDN DIF

9.8.4