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

Abstract

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, Marine Micropaleontology (2009Micropaleontology ( ), doi: 10.1016Micropaleontology ( /j.marmicro.2009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTThe available ecological and palaeoecological information for two sea ice-related marine diatoms 35 (Bacillariophyceae), Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen, 36 suggests that these two species have similar sea surface temperature (SST), sea surface salinity 37 (SSS) and sea ice proximity preferences. From phytoplankton observations, both are described as 38 summer or autumn bloom species, commonly found in low SST waters associated with sea ice, 39 although rarely within the ice. Both species form resting spores (RS) as irradiance decreases, SST 40 falls and SSS increases in response to freezing ice in autumn. Recent work analysing late 41Quaternary seasonally-laminated diatom ooze from coastal Antarctic sites has revealed that sub- that used a coupled atmosphere-sea ice-vegation model forced with orbital parameters and 57 greenhouse gas concentrations. We find that abundance of P. glacialis RS is favoured by higher 58 A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT4 winter and spring sea ice concentrations and that a climatically-sensitive threshold exists between 59 the abundance of P. glacialis RS and T. antarctica RS in the sediments. An increase to >0.1 for the 60 ratio of P. glacialis RS:T. antarctica RS indicates a change to increased winter sea ice 61 concentration (to >80% concentration), cooler spring seasons with increased sea ice, slightly 62 warmer autumn seasons with less sea ice and a change from ~7.5 months annual sea ice cover at a 63 site to much greater than 7.5 months. In the East Antarctic sediment record, an increase in the ratio 64 from <0.1 to above 0.1 occurs at the transition from the warmer Hypsithermal climate into the 65 cooler Neoglacial climate (~4 cal kyr) indicating that the ratio between these two diatoms has the 66 potential to be used as a semi-quantitative climate proxy. antarctica RS-dominated sub-laminae that were deposited during autumn (Stickley et al., 2005). antarctica RS and P. glacialis RS sub-laminae from both sites, and from both time intervals, occur 88 at the top of late summer/autumn terrigenous-rich diatom laminae, which supports the contention 89 that these two diatoms have broadly similar ecological pre...

Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by changes in insolation and ENSO variability

“…We suggest that, despite maximum summer insolation, summer duration was probably its shortest since the early Holocene, and that colder and longer winter and spring seasons would have likely promoted longer sea ice seasons. Such a scenario is supported by previous work, both locally in Marguerite Bay (Allen et al, 2010) and remotely in East Antarctica (Pike et al, 2009).…”

“…Other environmentally diagnostic and numerically abundant diatom species include the cold and warm varieties of Thalassiosira antarctica, which grow, respectively, at the sea ice edge when the duration of seasonal sea ice is greatest, and during the ice-free season (Buffen et al, 2007;Pike et al, 2009). Fragilariopsis curta, combined here with the very similar species Fragilariopsis cylindrus, is found close to sea ice (Buffen et al, 2007;Pike et al, 2008) and is used to reflect sea ice distribution.…”

On the phytoplankton bloom in coastal waters of southern King George Island (Antarctica) in January 2010: An exceptional feature?

“…For example, T. antarctica is the year-round dominant diatom in AB (Kopczyńska 1996) and has also been observed to produce large biomass accumulations in the Bellingshausen and Weddell Seas (Edwards et al 1998;Smetacek et al 1992). On the other hand, and according to paleoecological information, T. antarctica and Porosira glacialis are typical summer bloom species in Antarctica with similar ecological preferences, usually found in cold coastal waters at the sea ice edge (Pike et al 2009). Moreover, the same authors highlighted the fact that high fluxes of T. antarctica and P. glacialis resting spores to the sediment are associated with high concentrations of winter and spring sea ice that promote the buildup of large vegetative cell populations.…”

Diatom assemblages in the upper layer of bottom deposits: distribution over morphostructural shelf zones of the north-western Antarctic peninsula

“…Він представлений, переважно, хо-лодолюбивим різновидом [11]. Теплолюбивий різновид T. antarctica [6,9] складає незначну частку комплексів.…”