Publication Date:
2020-05-19
Description:
The large declines in Arctic sea-ice age and extent over the last decades could have
altered the diversity of sea-ice associated unicellular eukaryotes (referred to as seaice
protists). A time series from the Russian ice-drift stations from the 1980s to the
2010s revealed changes in community composition and diversity of sea-ice protists from
the Central Arctic Ocean. However, these observations have been biased by varying
levels of taxonomic resolution and sampling effort, both of which were higher in the
early years at drift stations on multiyear sea ice (MYI) in the Central Arctic Ocean. We
here combine the Russian ice-drift station data with more recent data to (1) identify
common sea-ice protists (in particular diatoms) in drifting sea ice of the Central Arctic
Ocean; (2) characterize the potential change in such communities over 35 years in
terms of species number and/or community structure; and (3) relate those shifts to
relevant environmental factors. In terms of relative abundance, pennate diatoms were
the most abundant sea-ice protists across the Arctic, contributing 60% on average
of counted cells. Two pennate colony-forming diatom species, Nitzschia frigida and
Fragilariopsis cylindrus, dominated at all times, but solitary diatom species were also
frequently encountered, e.g., Cylindrotheca closterium and Navicula directa. Multiyear
sea ice contained 39% more diatom species than first-year ice (FYI) and showed a
relatively even distribution along entire sea-ice cores. The decrease in MYI over the
last decades explained the previously reported decreases in sea-ice protist diversity.
Our results also indicate that up to 75% of diatom species are incorporated into FYI
from the surrounding sea ice and the water column within a few months after the initial
formation of the ice, while the remaining 25% are incorporated during ice drift. Thus,
changing freeze-up scenarios, as currently witnessed in the Central Arctic, might result
in long-term changes of the biodiversity of sea-ice protists in this region.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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