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Indices based on silicoflagellate assemblages offer potential for paleo-reconstructions of the main oceanographic zones of the Southern Ocean


Rigual-Hernandez, AS and Trull, TW and McCartney, K and Ballegeer, A-M and Lawler, K-A and Bray, SG and Armand, LK, Indices based on silicoflagellate assemblages offer potential for paleo-reconstructions of the main oceanographic zones of the Southern Ocean, Geo-Marine Letters, 36, (4) pp. 271-280. ISSN 1432-1157 (2016) [Refereed Article]

Copyright Statement

Copyright 2016 Springer-Verlag Berlin Heidelberg

DOI: doi:10.1007/s00367-016-0444-8


This study reports detailed silicoflagellate assemblage composition and annual seasonal flux from sediment traps at four locations along a transect across the Southern Ocean frontal systems. The four traps sampled the central Subantarctic Zone (SAZ, 47S site), the Subantarctic Front (SAF, 51S site), the Polar Frontal Zone (54S site) and the Antarctic Zone (61S site) across the 140E longitude. Annual silicoflagellate fluxes to the deep ocean exhibited a similar latitudinal trend to those of diatom fluxes reported in previous work, with maxima in the Antarctic Zone and minima in the Subantarctic Zone. The data suggest that, along with diatoms, silicoflagellates are important contributors to biogenic silica export at all sites, particularly in the Subantarctic Zone. Two main silicoflagellate genera were observed, with Stephanocha sp. (previously known as Distephanus) dominating polar waters and Dictyocha sp. important in sub-polar waters. This is consistent with previous use of the Dictyocha / Stephanocha ratio to infer paleotemperatures and monitor shifts in the position of the Polar Frontal Zone in the sedimentary record. It appears possible to further refine the application of this approach by using the ratio between two Dictyocha species, because Dictyocha aculeata dominated at the Subantarctic Front, while Dictyocha stapedia dominated in the central Subantarctic Front. Given the well-defined environmental affinities of both species, a new SAF silicoflagellate index (SAF-SI) based on this ratio is proposed as a useful diagnostic for SAF and SAZ water mass signatures in the Plio-Pleistocene and Holocene sedimentary record.

Item Details

Item Type:Refereed Article
Keywords:silicoflagellate assemblages, Southern Ocean, Subantarctic Zone, Polar Frontal Zone
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)
UTAS Author:Trull, TW (Professor Thomas Trull)
UTAS Author:Bray, SG (Mr Stephen Bray)
ID Code:113641
Year Published:2016
Web of Science® Times Cited:5
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2017-01-11
Last Modified:2017-10-31

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