Planktonic foraminifera in the sea of Okhotsk : population and stable isotopic analysis from a sediment trap
Citable URI
https://hdl.handle.net/1912/5673Location
53°19'N, 149°50'EDOI
10.1575/1912/5673Keyword
Marine plankton; Ocean temperatureAbstract
The relationship of planktonic foraminiferal populations and stable
isotopes to synoptic sea surface temperatures (SST's) was examined in the Sea
of Okhotsk, using sediment trap samples (trap deployed Aug. '90 - Aug. '91;
53°19'N, 149°50'E) and AVHRR satellite sea surface temperature data.
Synoptic SST's for the deployment ranged between -1.2 and 14.8°C. Two
species dominated total yearly foraminiferal flux: N. pachyderma (left) and G.
bulloides, with 57% and 31% of yearly flux, respectively. Calcification depths
(from δ180eq. calcite) for these species ranged between 20 and 40 meters. Due
to the highly stratified water column in the Sea of Okhotsk, these
foraminifera experienced temperatures much colder than SST, and use of
standard paleotemperature proxies significantly underestimates SST. The
average paleotemperatures calculated from both δ180pachy and δ18Dbull were
5-6°C lower than average synoptic SST. Faunal indicators were consistent
with this finding, with the N. pachyderma left-to-right coiling ratios >98% for
the entire trap deployment. These ratios would suggest maximum seasonal
SST's no greater than 10°C, nearly 5°C colder than the actual sea surface
temperature maximum. The results from this study indicate that in highly
stratified water columns, standard paleotemperature proxies may yield results
as much as 5°C cooler than actual sea surface conditions.
Description
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1996
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Suggested Citation
Thesis: Alderman, Susan E., "Planktonic foraminifera in the sea of Okhotsk : population and stable isotopic analysis from a sediment trap", 1996-05, DOI:10.1575/1912/5673, https://hdl.handle.net/1912/5673Related items
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