''Fragilariopsis cylindrus'' is a pennate sea-ice

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

that is found native in the Argentine Sea and

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...

waters, with a pH of 8.1-8.4. It is regarded as an

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

for polar water.

Description

''Fragilariopsis cylindrus'' is a

unicellular A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist indiv ...

that is important due to its ecological roles. This is because it is major contributor to

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

processes, responsible for 20% global

carbon fixation Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as ...

, and forms a substantial basis of the marine food web, making up 40% of marine primary productivity. ''F. cylindrus'' is found native to the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

, with their proximal side valve mantle being 1.6 μm, their girdle 0.75μm, apical axis ranging between 15.5μm to 55.0μm, transapical axis ranging from 2.4μm to 4.0μm, and their transapcial axis ranging from 2.4μm to 4.μm. Their transapical striae count is 10-16, with a mean of 10μm, while their row of poroids range from 50 to 56, in 10μm. ''F. cylindrus'' typically forms large populations in the bottom layer of sea ice, as well as in the wider sea-ice zone, which includes open waters. It is known for its ability to survive temperatures below 0°C, high

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

, the semi-enclosed pore systems within the ice, as well as low

diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...

rates of dissolved gases and exchange of inorganic

nutrients A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

that occur within their environment. ''F. cylindrus'' is a

phototropic Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hor ...

organism, but is able to sustain essential

metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

processes in the dark, ensuring rapid recovery upon re-illumination, and allowing them to survive long-term darkness. Gram stain, cellulose activity, growth rate, motility and the microbe's ability to resist/produce antibiotics have are unknown at this moment.

References

{{Taxonbar, from=Q11922683 Bacillariales