Parmales Explained

The Parmales are an order of marine microalgae within the Bolidophyceae class. They are found worldwide and characterized by a cell wall composed of 5-8 interlocking silica plates with distinct forms.[1] They were initially thought to be loricate choanoflagellates[2] but were shown to be a separate phyla entirely upon the discovery of chloroplasts, placing it among the photosynthetic stramenopiles.[3]

The group is divided into two distinct morphologies- the naked and mobile bolidophyte form and the non-mobile and silica-plate covered parmalean form. The bolidophyte form lacks silica plates and has two unequal flagella inserted ventrally, vaguely reminiscent of Chlamydomonas.[3] The parmalean form is similar to the diatoms as it is coated in silicate plates. These silicate plates are used to divide the Parmales into separate genera based upon the number and location of the siliceous plates. Unlike the diatoms, the Parmales are able to grow in silica-limiting environments because the synthesis of the silica plates is not directly connected to growth or reproduction.[4]

The Parmales actively feed on nanophytoplankton such as Prochlorococcus and Synechococcus and are one of the most important grazers on these cyanobacteria in oligotrophic waters.[5] This heterotrophy serves as an important step in the foundation of the microbial loop.

Etymology

The name comes from the Latin word for a small, round shield carried by infantry and cavalry. It refers to the silica plates that the Parmales are covered by.[6]

Distribution

Parmales can be found in all the major world oceans. However, their density is consistently low (10-100 cells/ml) and they represent at most 3% of the phytoplankton present.[3] They are most abundant in polar and subarctic waters but are also capable of growing in tropical and subtropical locations.[7] [8]

Within the water column, Parmales are found in the upper, euphotic portion where they remain without difficulty due to their small size. It is currently unknown whether they have mechanisms to regulate buoyancy.[9]

Parmales have also been found as fossils in the Middle America Trench in sediments from the mid to late Quaternary period.[10] Older fossils have been reported but are unverifiable.[11]

Taxonomy

Although initially placed within the Chrysophyceae, Parmales were shown in 2016 to belong to the Bolidophyceae[6] [3]

Notes and References

  1. Book: Konno. Susumu. Jordan. Richard W. Parmales. eLS. 10.1002/9780470015902.a0023691. en. 2012. 978-0470016176.
  2. Silver. M. W.. Mitchell. J. G.. Ringo. D. L.. Siliceous nanoplankton. II. Newly discovered cysts and abundant choanoflagellates from the Weddell Sea, Antarctica. Marine Biology. 1980. 58. 3. 211–217. 10.1007/BF00391878. 84302442.
  3. Ichinomiya. Mutsuo. dos Santos. Adriana Lopes. Gourvil. Priscillia. Yoshikawa. Shinya. Kamiya. Mitsunobu. Ohki. Kaori. Audic. Stéphane. de Vargas. Colomban. Noël. Mary-Hélène. Vaulot. Daniel. Kuwata. Akira. Diversity and oceanic distribution of the Parmales (Bolidophyceae), a picoplanktonic group closely related to diatoms. The ISME Journal. 22 March 2016. 10. 10. 2419–2434. 10.1038/ismej.2016.38. 27003244. 5030691.
  4. Yamada. Kazumasa. Yoshikawa. Shinya. Ichinomiya. Mutsuo. Kuwata. Akira. Kamiya. Mitsunobu. Ohki. Kaori. Lovejoy. Connie. Effects of Silicon-Limitation on Growth and Morphology of Triparma laevis NIES-2565 (Parmales, Heterokontophyta). PLOS ONE. 23 July 2014. 9. 7. e103289. 10.1371/journal.pone.0103289. 25054645. 4108440. 2014PLoSO...9j3289Y. free.
  5. Frias-Lopez. Jorge. Thompson. Anne. Waldbauer. Jacob. Chisholm. Sallie W.. Use of stable isotope-labelled cells to identify active grazers of picocyanobacteria in ocean surface waters. Environmental Microbiology. February 2009. 11. 2. 512–525. 10.1111/j.1462-2920.2008.01793.x. 19196281. 2702499.
  6. Booth. Beatrice C.. Marchant. Harvey J.. Parmales, A New Order of Marine Chrysophytes, with Descriptions of Three New Genera and Seven New Species. Journal of Phycology. June 1987. 23. s2. 245–260. 10.1111/j.1529-8817.1987.tb04132.x. 84582735.
  7. Fujita. Ryohei. Jordan. Richard W.. Tropical Parmales (Bolidophyceae) assemblages from the Sulu Sea and South China Sea, including the description of five new taxa. Phycologia. September 2017. 56. 5. 499–509. 10.2216/16-128.1. 90190189.
  8. Ichinomiya. M. Kuwata. A. Seasonal variation in abundance and species composition of the Parmales community in the Oyashio region, western North Pacific. Aquatic Microbial Ecology. 6 July 2015. 75. 3. 207–223. 10.3354/ame01756. free.
  9. Book: Kuwata. A.. Jewson. D.H.. Ohtsuka. S.. Suzaki. T.. Horiguchi. T.. Suzuki. N. Not. F.. Marine Protists, Diversity and dynamics. 2015. Springer. Tokyo. 251–275. Ecology and evolution of marine diatoms and Parmales.
  10. Stradner. H.. Allram. F.. Notes on an enigmatic siliceous cyst, Middle America Trench, Deep Sea Drilling Project Hole 490. Deep Sea Drilling. 66. 4. 641–642. 10.2973/dsdp.proc.66.124.1982. Initial Reports of the Deep Sea Drilling Project. 1982. free.
  11. Konno. S.. Ohira. R.. Komuro. C.. Harada. N.. Jordan. R. Six new taxa of subarctic Parmales (Chrysophyceae). J. Nannoplankton Res.. 2007. 29. 2. 108–128. 10.58998/jnr2153 . 259979898 . 12 April 2018. 13 April 2018. https://web.archive.org/web/20180413043349/http://ina.tmsoc.org/JNR/online/29/Konno%20et%20al%202007%20JNR%2029-2%20Parmales.pdf. dead.

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