Planktonic foraminiferal faunal study and Mg/Ca-temperature calibration at the Hawaii Ocean Time-Series
- Degree Grantor:
- University of California, Santa Barbara. Geological Sciences
- Degree Supervisor:
- David W. Lea and Syee Weldeab
- Place of Publication:
- [Santa Barbara, Calif.]
- Publisher:
- University of California, Santa Barbara
- Creation Date:
- 2016
- Issued Date:
- 2016
- Topics:
- Paleoclimate science, Geochemistry, and Chemical oceanography
- Keywords:
- Foraminifera,
Paleothermometry,
Proxy calibration, and
Mg/Ca. - Genres:
- Online resources and Dissertations, Academic
- Dissertation:
- M.S.--University of California, Santa Barbara, 2016
- Description:
Planktonic foraminiferal assemblages and geochemistry (i.e. Mg/Ca and delta 18O) are among the most widely-utilized climate proxies in paleoceanographic studies. Foraminifera-based sea surface temperature (SST) reconstructions are interpreted as representative of mean annual conditions. However, foraminifera fluxes vary seasonally, temperature reconstructed from this material will harbor a strong seasonal imprint. Additionally, recent studies have suggested that Mg/Ca is affected by salinity, which is not accounted for in most existing calibrations and has varied significantly over glacial-to-interglacial timescales.
Well-preserved, bi-weekly sediment trap samples and accompanying high-resolution water column measurements from the Hawaii Ocean Time-Series (HOT) at Station ALOHA (A Long Term Oligotrophic Habitat Assessment) provide ideal conditions to evaluate temporal variability in foraminiferal flux and calibrate Mg/Ca to precisely-measured environmental parameters. A 2.5 year faunal record at HOT shows total planktonic foraminifera fluxes are highest (>100 shells/m 2/day) from May-October, coincident with warmest SSTs and high primary productivity. Annual peaks occur in July and late September; unique 5-day sampling reveals that these maxima occur in response to summer blooms of N 2-fixing bacteria.
Low salinity and pH variability at ALOHA (0.7 psu and 0.11 units, respectively) allows the temperature influence on Mg/Ca to be isolated and quantified. Globigerinoides ruber (sensu lato) temperature sensitivity ranges from 6.3 +/- 1.6% to 7.7 +/- 2.4% Mg/Ca per degrees Celsius, with higher values arising from the assumption of deeper habitat depth. T. sacculifer exhibits a similar temperature sensitivity range, up to 7.7 +/- 2.4% for a subsurface habitat. Our results highlight the sensitivity of Mg/Ca-temperature regressions to parameter choices used in calibration.
- Physical Description:
- 1 online resource (62 pages)
- Format:
- Text
- Collection(s):
- UCSB electronic theses and dissertations
- Other Versions:
- http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:10194238
- ARK:
- ark:/48907/f3rr1zc3
- ISBN:
- 9781369341294
- Catalog System Number:
- 990047189700203776
- Copyright:
- Minda Monteagudo, 2016
- Rights:
In Copyright
- Copyright Holder:
- Minda Monteagudo
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