Diatoms preserved in surface sediments of the northeastern Kerguelen Plateau

An "island mass effect" was observed from the sedimentary distribution of diatoms on the northeastern Kerguelen Plateau. Five new samples placed in context to species distributions previously reported from the Permanently Open Ocean Zone (POOZ) revealed a plateau community dominated by thr...

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Bibliographic Details
Published in:Deep Sea Research Part II: Topical Studies in Oceanography
Main Authors: Armand, LK, Crosta, X, Quéguiner, B, Mosseri, J, Garcia, N
Format: Article in Journal/Newspaper
Language:English
Published: 2008
Subjects:
270705 Palaeoecology
260401 Biological Oceanography
260499 Oceanography not elsewhere classified
270709 Biogeography
Bacillariophyceae Sediments Fluff layer Biogenic silica Chlorophyll a Southern Ocean
Antarctic
Southern Ocean
Kerguelen
Antarc*
Antarctica
Sea ice
Online Access:https://eprints.utas.edu.au/6655/
https://eprints.utas.edu.au/6655/1/Armand_et_al._DSR_11_2008.sediments.pdf
https://doi.org/10.1016/j.dsr2.2007.12.031
Description
Summary:An "island mass effect" was observed from the sedimentary distribution of diatoms on the northeastern Kerguelen Plateau. Five new samples placed in context to species distributions previously reported from the Permanently Open Ocean Zone (POOZ) revealed a plateau community dominated by three species/taxa: Fragilariopsis kerguelensis, Thalassionema nitzschioides f. nitzschioides and Chaetoceros Hyalochaete resting spores. Intermediate abundances of Thalassiosira antarctica were unique to the plateau sediment signature as were increased abundances of Eucampia antarctica v. antarctica. The off-plateau sediment sample contained typical POOZ sediment distributions dominated by F. kerguelensis, Thalassiosira lentiginosa and Thalassiothrix antarctica. The role of deposition from the surface waters to the sediments was investigated by comparison to the diatom thanatocoenose observed in surface waters. These results suggest that the use of sediment abundances of C. Hyalochaete resting spores and F. kerguelensis to determine past productivity events (such as wind-sourced iron enrichment of the Southern Ocean at the Last Glacial Maximum) is not straightforward. The elevated abundance of T. nitzschioides f. nitzschioides on the plateau did not indicate an iron-deplete regime but the converse. For the evaluation of paleo-productivity hypotheses for the open Southern Ocean, we suggest caution in the use of Subantarctic and Kerguelen Plateau sediment signatures, and emphasize that there is a need to also study Antarctic coastal and especially sea-ice melt-water stimulated blooms.

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