Observations on the relationship between the Antarctic coastal diatoms Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen and sea ice concentrations during the Late Quaternary

• Published in: Marine Micropaleontology
• Main Authors: Pike, Jennifer, Crosta, Xavier, Maddison, Eleanor J., Stickley, Catherine E., Denis, Delphine, Barbara, Loïc, Renssen, Hans
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2009
• Subjects: Antarctic; George V Coast; Mertz-Ninnis Trough; Princess Elizabeth Land; Svenner; Svenner Channel; The Antarctic; Antarc*; Antarctica; Iceberg*; Sea ice
• Online Access: https://oro.open.ac.uk/17678/; https://oro.open.ac.uk/17678/1/Pike_et_al.pdf; https://doi.org/10.1016/j.marmicro.2009.06.005

The available ecological and palaeoecological information for two sea ice-related marine diatoms (Bacillariophyceae), Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen, suggests that these two species have similar sea surface temperature (SST), sea surface salinity (SSS) and sea ice proximity preferences. From phytoplankton observations, both are described as summer or autumn bloom species, commonly found in low SST waters associated with sea ice, although rarely within the ice. Both species form resting spores (RS) as irradiance decreases, SST falls and SSS increases in response to freezing ice in autumn. Recent work analysing late Quaternary seasonally-laminated diatom ooze from coastal Antarctic sites has revealed that sub-laminae dominated either by T. antarctica RS, or by P. glacialis RS, are nearly always deposited as the last sediment increment of the year, interpreted as representing autumn flux. In this study, we focus on sites from the East Antarctic margin and show that there is a spatial and temporal separation in whether T. antarctica RS or P. glacialis RS form the autumnal sub-laminae. For instance, in deglacial sediments from the Mertz Ninnis Trough (George V Coast) P. glacialis RS form the sub-laminae whereas in similar age sediments from Iceberg Alley (Mac.Robertson Shelf) T. antarctica RS dominate the autumn sub-lamina. In the Dumont d–Urville Trough (Adélie Land), mid Holocene (Hypsithermal warm period) autumnal sub-laminae are dominated by T. antarctica RS whereas late Holocene (Neoglacial cool period) sub-laminae are dominated by P. glacialis RS. These observations from late Quaternary seasonally laminated sediments would appear to indicate that P. glacialis prefers slightly cooler ocean-climate conditions than T. antarctica. We test this relationship against two down-core Holocene quantiative diatom abundance records from Dumont d–Urville Trough and Svenner Channel (Princess Elizabeth Land) and compare the results with SST and sea ice concentration results of an ...