Glacial‐interglacial size variability in the diatom <i>Fragilariopsis kerguelensis</i>: Possible iron/dust controls?

Cortese, Giuseppe; Gersonde, Rainer; Maschner, Katharina; Medley, Pamela

doi:10.1029/2011pa002187

Cited by 28 publications

(32 citation statements)

References 58 publications

(84 reference statements)

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“…The authors related the presence of F. kerguelensis populations with larger average cell size to alleviation of iron limitation during iron-replete glacial conditions (Cortese & Gersonde, 2007). The possible link between glacialinterglacial changes in the average cell size of F. kerguelensis and iron availability (cells with a larger valvar area occurring in glacial periods characterized by a higher Fe deposition from atmospheric dust) was further confirmed by Cortese et al (2012). The authors also reported a larger valvar area for F. kerguelensis inside fertilized patches of two iron-fertilization experiments.…”

Section: Fragilariopsis Kerguelensis As a Palaeo-proxy: A Life Cycle mentioning

confidence: 52%

“…Valve morphometrics of Fragilariopsis kerguelensis have been suggested to have potential for reconstructing palaeo-oceanographic conditions in the Southern Ocean, based on the fact that the average frustule size varies amongst sites characterized by different productivity regimes (Cortese & Gersonde, 2007;Crosta, 2009;Cortese et al, 2012). Cortese & Gersonde (2007) analysed the valve length and valve area of F. kerguelensis frustules in surface sediments from the Pacific and Atlantic sectors of the Southern Ocean (providing a spatial gradient) and one piston core (giving a temporal gradient) near the Antarctic Polar Front.…”

Section: Fragilariopsis Kerguelensis As a Palaeo-proxy: A Life Cycle mentioning

confidence: 99%

“…Variations in valve size over geological time scales, as well as short-term changes resulting from iron addition experiments (Cortese et al, 2012), prompted us to investigate the life cycle of this important diatom. Changes in cell size frequency distribution (SFD) in many diatoms are linked to the functioning of the life cycle.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Genetic characterization and life cycle of the diatomFragilariopsis kerguelensis

Fuchs

Scalco

Kooistra

et al. 2013

European Journal of Phycology

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The planktonic diatom Fragilariopsis kerguelensis plays an important role in the biogeochemical cycles of the Southern Ocean, where remains of its frustules form the largest deposit of biogenic silica anywhere in the world. We assessed the genetic identity of 26 strains, from cells collected at various sites in the Southern Ocean, using three molecular markers, LSU and ITS rDNA and rbcL. The LSU sequences were identical among the tested strains, ITS sequences were highly similar, and only one base pair difference was detected among the rbcL sequences. These results, together with a large number of successful mating experiments demonstrated that the strains belong to a single biological species. We investigated the mating system and life cycle traits of F. kerguelensis. Cell size diminished gradually in clonal strains. Gamete formation only occurred when strains of opposite mating type -within a cell size range of 7-36 µm -were mixed together. Two binucleate gametes were formed in each gametangium and gamete conjugation produced a zygote that had four nuclei and was surrounded by thin siliceous scales. Two out of the four nuclei subsequently degenerated and the zygote expanded to form an auxospore surrounded by a transverse and a longitudinal perizonium. Staining with the fluorochrome PDMPO provided for the first time a clear demonstration that the longitudinal perizonium is formed after auxospore expansion is complete. Initial cells produced within the mature auxospores were 78-101 µm in length. Various authors have shown that the average valve size of F. kerguelensis varies in sediment samples collected in regions and seasons with different primary production regimes and this parameter has thus been proposed as a biological proxy for palaeoproductivity. A better understanding of the life cycle of F. kerguelensis should help the design of future investigations aimed at testing the link between cell size distribution in the natural environment and the role that environmental factors might have in the regulation of population cell size.

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Section: Fragilariopsis Kerguelensis As a Palaeo-proxy: A Life Cycle mentioning

confidence: 52%

Section: Fragilariopsis Kerguelensis As a Palaeo-proxy: A Life Cycle mentioning

confidence: 99%

See 1 more Smart Citation

Genetic characterization and life cycle of the diatomFragilariopsis kerguelensis

Fuchs

Scalco

Kooistra

et al. 2013

European Journal of Phycology

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“…Similarly, the down-core records from the Atlantic and Indian Antarctic Polar Front (APF), and Atlantic and Indian Sub-Antarctic Front (SAF) show larger F. kerguelensis mean valve area (FkergArea) throughout the last glacial period during higher aeolian dust flux to the SO. FkergArea generally declined during the deglacial and the Holocene periods along with a reduction in the dust flux (Cortese & Gersonde 2007, Cortese et al 2012, Shukla et al 2013. This pattern was reproducible until termination V,~430 cal kyrs BP (Cortese et al 2012).…”

Section: Introductionmentioning

confidence: 88%

“…Fragilariopsis kerguelensis (O'Meara) Hustedt is the most abundant diatom species in the surface sediments and in the down-core records of the open Southern Ocean (SO) (Zielinski & Gersonde 1997, Crosta et al 2005a and is believed to be a major silica carrier to the sea floor (Cortese & Gersonde 2008, Abelmann et al 2015. Fragilariopsis kerguelensis size variability has recently been proved useful to infer recent (Cortese & Gersonde 2007) and past oceanic conditions at the glacialinterglacial timescales (Cortese et al 2012, Shukla et al 2013, Nair et al 2015. A study conducted on sediment traps and surface sediments from the sea-ice zone to the subtropical zone of the Atlantic SO suggested a strong correlation of F. kerguelensis size with iron availability (Cortese & Gersonde 2007), consistent with the findings of culture experiments (Assmy et al 2006, Timmermans & van der Wagt 2010 and in situ iron fertilization experiments (Assmy et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Fragilariopsis kerguelensis size variability from the Indian subtropical Southern Ocean over the last 42 000 years

Shukla

Crosta

2016

Antarctic Science

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In the open Southern Ocean (SO), both modern and past size changes of the diatom Fragilariopsis kerguelensis appear to be strongly controlled by iron availability. Conversely, sea surface temperatures (SST) and sea ice seasonal dynamics take over in the seasonal sea-ice zone where iron is not limiting. No information exists on F. kerguelensis biometry from the subtropical SO, on the other extreme of the thermal and nutrient gradients. We present here new data on mean valve area of F. kerguelensis (FkergArea) from a sediment core covering the last ~42 cal kyrs from the southern Subtropical Front (SSTF) of the Indian sector of the SO, where iron and silica stocks are thought to have been consistently low over this period. Our results suggest that larger F. kerguelensis valves occurred during the Last Glacial period, and declined during the Holocene period. These findings indicate that more favourable SST, within the F. kerguelensis ecological range, during the Last Glacial period may have enabled F. kerguelensis to make better use of the low silica stocks prevailing in the subtropical zone leading to larger valves. Conversely, declining FkergArea during the deglacial and the Holocene periods may have been a result of higher SST which hampered the utilization of silica.

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Glacial‐interglacial variability in diatom abundance and valve size: Implications for Southern Ocean paleoceanography

Nair

Mohan

Manoj³

et al. 2015

Paleoceanography

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Antarctic sea ice extent along with Southern Ocean biological productivity varied considerably during glacial-interglacial periods, and both are known to have played a considerable role in regulating atmospheric CO 2 variations in the past. Here we present data on diatom absolute abundance (valves/g of sediment) and size over the past~42 ka B.P. and how they link to glacial-interglacial changes in Antarctic sea ice extent, Southern Ocean frontal systems, and aeolian dust flux. Our records of sea ice and permanent open ocean zone diatom abundances suggest a shift in the Antarctic winter sea ice limit and Polar Front respectively up to the modern-day Polar Frontal Zone during marine isotopic stages (MIS) 2 and late MIS 3. In addition to glacial shifts in the Polar Front, diatom assemblages also recorded a plausible northward shifts in Polar Front during few intervals of MIS 1. Glacial periods north of the Polar Front in the Indian sector of the Southern Ocean were characterized by higher total diatom abundance, larger Fragilariopsis kerguelensis apical length, and Thalassiosira lentiginosa radius. This is probably a consequence of (1) a northward expansion of the opal belt, a region characterized by high production and export of biogenic silica; (2) an increase in terrigenous input, via erosion of Crozet Islands; and (3) the alleviation of iron deficit by high input of Fe-bearing dust. The larger and highly silicified diatoms such as F. kerguelensis and T. lentiginosa may have mainly contributed in transporting biogenic silica and organic carbon to the seabed for the last 42 ka, in the northern Polar Frontal Zone of the Indian sector of the Southern Ocean.

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Glacial‐interglacial size variability in the diatom Fragilariopsis kerguelensis: Possible iron/dust controls?

Cited by 28 publications

References 58 publications

Genetic characterization and life cycle of the diatomFragilariopsis kerguelensis

Genetic characterization and life cycle of the diatomFragilariopsis kerguelensis

Fragilariopsis kerguelensis size variability from the Indian subtropical Southern Ocean over the last 42 000 years

Glacial‐interglacial variability in diatom abundance and valve size: Implications for Southern Ocean paleoceanography

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