Fragilariopsis kerguelensis explained

Fragilariopsis kerguelensis,^[1] is a pennate diatom native to the Southern Ocean. It has been characterized as "the most abundant diatom in the Antarctic Seas".^[2]

Description

Fragilariopsis kerguelensis is a unicellular, phototrophic, microalga with a range in size of 10 - 80 μm.^[3] It is encased in a heavily silicified cell wall, called the frustule, and is identified by its unique theca, raphe and striations, which distinguish it from other diatoms.^[4] They are native to pelagic environments of the Southern Ocean within a temperature range of -1° to 18° C. F. kerguelensis is known to form community chains that consist of 20-100 cells and can be up to 300 μm long.^[5]

Use as a paleoceanographic proxy

Fragilariopsis kerguelensis is well preserved in the fossil record and commonly referenced as a paleoceanographic or paleoclimatic proxy. F. kerguelensis comprises the largest deposit of biogenic silica in the world (~75%) despite only accounting for 20% of global production.^[6] It is an open water species and is found in its highest abundance between the Antarctic Circumpolar Current and the Subtropical Front.^[7] This, along with its tendency to increase valve size near polar fronts, makes F. kerguelensis an ideal indicator of paleoclimate polar front or low-carbon, high-silica exporting regimes.^{[8] [9]} Modern assemblages with F. kerguelensis can be used to calculate past sea surface temperature through the use of transfer functions.^[10]

Notes and References

1. O'Meara. E. the diatomaceous gatherings made at Kerguelen's Land. Journal of the Linnean Society, Botany. 1877. 15. 55–59.
2. Hart. T.J. Phytoplankton periodicity in Antarctic surface waters. Discovery Rep. 1942.
3. Smetacek. V. Diatoms and the ocean carbon cycle. Protist. 1999. 150. 1. 25–32. 10.1016/s1434-4610(99)70006-4. 10724516.
4. Web site: Fragilariopsis kerguelensis (O'Meara) Hustedt, 1952. World Register of Marine Species. World Register of Marine Species.
5. Smetacek. V. Assmy. P. Henjes. J. The role of grazing in structuring Southern Ocean pelagic ecosystems and biogeochemical cycles. Antarctic Science. 2004. 16. 4. 541–558. 10.1017/s0954102004002317. 2004AntSc..16..541S. 131176101.
6. Verity. P.G. Smetacek. V. Organism life cycles, predation, and the structure of marine pelagic ecosystems. Marine Ecology Progress Series. 1996. 130. 1. 231–250. 10.3354/meps130277. 1996MEPS..130..277V. free.
7. Crosta. X. Romero. O. Armand. L.K. Pichon. J.J. The biogeography of major diatom taxa in Southern Ocean sediments: 2. Open ocean related species. Palaeogeography, Palaeoclimatology, Palaeoecology. 2005. 223. 1. 6–92. 10.1016/j.palaeo.2005.03.028. 2005PPP...223...66C.
8. Cortese. G. Gersonde. R. Morphometric variability in the diatom Fragilariopsis kerguelensis: Implications for Southern Ocean paleoceanography. Earth Planet. Sci. Lett.. 2007. 257. 3–4. 526–544. 10.1016/j.epsl.2007.03.021. 2007E&PSL.257..526C.
9. Web site: Profile: Fragilariopsis kerguelensis - Biota - Confluence. SOKI Wiki. Antarctic Climate and Ecosystems Co-operative Research Centre.
10. Zielinski. U. Gersonde. R. Diatom distribution in Southern Ocean surface sediments (Atlantic sector): Implications for paleoenvironmental reconstructions. Palaeogeography, Palaeoclimatology, Palaeoecology. 1997. 129. 3–4. 213–250. 10.1016/s0031-0182(96)00130-7. 1997PPP...129..213Z.