Fragilariopsis cylindrus | |
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Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Stramenopiles |
Phylum: | Gyrista |
Subphylum: | Ochrophytina |
Class: | Bacillariophyceae |
Order: | Bacillariales |
Family: | Bacillariaceae |
Genus: | Fragilariopsis |
Species: | F. cylindrus |
Binomial name | |
Fragilariopsis cylindrus | |
Synonyms [2] | |
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Fragilariopsis cylindrus [3] is a sympagic (associated with sea ice) and/or planktonic bipolar pennate diatom that can form bloom in spring. [4] [5] This psychrophilic unicellular eukaryotic microalgae is an indicator of polar waters and the ecosystem associated with sea ice. [6] It is a model organism to understanding the ecophysiological and fundamental mechanisms of cold-adapted life. [7] [8]
Fragilariopsis cylindrus is a pennate raphid diatom with a retangular cell with an elongated apical valve ranging from 15 to 55 μ and a transapical axis ranging from 2.4 to 4 μm [9] . Like other diatoms, F. cylindrus presents a cell wall composed of two biogenic silica valves, the frustule. It is also possible to note the presence of an eccentric raphe canal stretched by fibulae. The cell is generally presents two chloroplasts distributed at each pole of the cell surrounding the cell nucleus.
Fragilariopsis cylindrus is cracterised by a predominantly chain-formed colonial lifestyle and builds large populations at the bottom of sea ice (sea-ice water interface), as well as in the sea-ice margin zone which includes open water [6] [4] . It is known for its success in growing at temperatures below 0°C and has an optimum growth temperature of 4-5°C and an letal limit of ≤ +10°C [10] . As a sympagic microalgae , F. cylindrus can cope with a high salinity environment, typically found in brine channels, by producing large amounts of polysaccharide-rich extracellular polymeric substances (EPS) [11] .
F. cylindrus is a phototropic organism, but is able to sustain essential metabolic processes in the dark, ensuring rapid recovery upon re-illumination, and allowing them to survive long-term darkness. [12]
A diatom is any member of a large group comprising several genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion tonnes of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half-mile deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression, which was once made up of a system of fresh-water lakes.
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A sea ice brine pocket is an area of fluid sea water with a high salt concentration trapped in sea ice as it freezes. Due to the nature of their formation, brine pockets are most commonly found in areas below −2 °C (28 °F), where it is sufficiently cold for seawater to freeze and form sea ice. Though the high salinity and low light conditions of brine pockets create a challenging environment for marine mammals, brine pockets serve as a habitat for various microbes. Sampling and studying these pockets requires specialized equipment to accommodate the hypersaline conditions and subzero temperatures.
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