Phytoplankton Blooms on the Barents Shelf
“Mid‐ to higher‐latitude shallow marine environments are suggested to serve as refugia for
organisms during intervals of rapid environmental change associated with hyperthermals. To understand the
role of these environments during hyperthermals, we herein investigate the Permian–Triassic environmental
crisis, which led to the most severe mass extinction event in the Phanerozoic. Our analysis of siliciclastic
deposits from the Boreal Ocean from Lusitaniadalen, Svalbard, reveals a distinct increase of the lipid
biomarkers C33‐n‐alkylcyclohexane (C33‐n‐ACH) and phytanyl toluene following the extinction event. This
increase does not appear to reflect facies changes. Rather, it coincides with the extinction horizon, and persists
into the lowermost Triassic (Griesbachian). Our findings suggest that neither C33‐n‐ACH nor phytanyl toluene
are linked to short periods of photic zone euxinia recorded at Lusitaniadalen, but rather are derived from a
specific group of phytoplankton. This indicates that higher‐latitude ecosystems may have supported regional
blooms of unknown primary producers after the Permian–Triassic mass extinction, thus explaining the selective
survival of some marine organisms. We also identify (albeit in lower abundance) C33‐n‐ACH and its
pseudohomologs in northern Italy, which is the first report of n‐ACHs in the tropical Tethys region across the
Permian–Triassic transition outside of South China, highlighting the wide paleogeographic distribution of this
biomarker. Phytanyl toluene, however, is found exclusively in deposits recording higher‐latitude ecosystems,
and is likely linked to organisms occupying a similar ecological niche as the source organism of C33‐n‐ACH in
these settings.” open access!