Rhizosolenia
Classification
Eukaryota; Ochrophyta; Coscinodiscophyceae; Rhizosoleniales; Rhizosoleniacease [Others may be used. Use NCBI link to find]
Species
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NCBI: Taxonomy |
Rhizosolenia acicularis; R. acuminata; R. acuminate; R. alata forma gracillima; R. alata forma curvirostris; R. alata forma gracillima; R. alata forma indica; R. alata gracillima; R. alata inermis; R. antarctica; R. antennata; R. antennata forma semispina; R. arafurensis; R. barboi; R. bergonii; R. bezrukovae; R. borealis; R. braunii; R. bulbosa; R. calcar-avis; R. castracanei; R. castracanei var. neglecta; R. chunii; R. clevei; R. clevei var. communis; R. cochlea; R. costata; R. crassa; R. crassispina; R. cretacea; R. curvata; R. curvirostria; R. curvirostris; R. debyana; R. decipiens; R. drafurensis; R. eriensis var. gracilis; R. eriensis var. morosa; R. eriensis var. morsa; R. faeroensis ; R. fallax; R. firma; R. formosa; R. fragillissima; R. gracilis; R. gravida; R. hebetata; R. hebetata forma semispina; R. hyalina; R. imbricata; R. interposita; R. longiseta; R. massiva; R. minima; R. miocenica; R. morsa; R. norwegica; R. ostenfeldii; R. palliola; R. pokrovskajae; R. polydactyla; R. polydactyla forma squamosa; R. praealata; R. praebarboi; R. pungens; R. rhombus; R. robusta; R. setigera; R. sigma; R. sima; R. sima forma silcea; R. similis; R. similoides; R. simplex; R. stolterforthii; R. striata; R. styliformis; R. temperei; R. truncata; R. twistata
Description and Significance
Rhizosolenia was discovered in 1843 floating in large very delicate mats in oceans of warm latitudes. Rhizosolenia is a cylindrical diatom with a silica shell. Rhizosolenia species can be found in marine and brackish water. Some species are also found in sediments. Rhizosolenia plays a significant role in the carbon, silica and nitrogen cycles in the oligotrophic seas.
The increases of some species of Rhizosolenia are responsible for lowering the numbers of good phytoplankton in certain seas due to competition of nutrients. Rhizosolenia can also cause fish kills by clogging the gills with their hard silica exterior and from post-bloom anoxia. At the same time, live and dead cells of Rhizosolenia are used by bacteria and benthic animals for nutrients. Invertebrates cannot use them directly for nutrients because of the morphological structure of the cells.
Genome Structure
There has not been a genome project on Rhizosolenia spp. at this time.
Cell Structure, Metabolism and Life Cycle
Rhizosolenia is a unicellular rod shaped diatom and ranges in diameter size from 2.5-170 µm. The cell wall is made of a silica shell comprised of two separate valves, also known as a frustule. The cell can synthesize the biogenic silica needed for the construction of the frustules. In addition the total silica production contributes a siginificant amount in the global marine silica cycle. Rhizosolenia is mostly abundant in a mat formation containing communities of multiple Rhizosolenia species. The mats can be comprised of short chains of only a few cells or larger rigid chains ranging from 1-30cm wide.
The size of the large mat communities can be a disadvantage in survival when competing with nano and pico sized organisms in an oligotrophic aquatic environment. To overcome this disadvantage, Rhizosolenia mats photosynthesize at the surface and then undergo a vertical migration (>300m) to exploit nutrients.
With the increase of carbohydrates in the cell from photosynthesis the cell becomes negatively buoyant and has a downward migration. As the carbohydrates are consumed and there is an uptake of nitrate a positively buoyant upward vertical migration takes place. The migration process can take 3.4-5.4 days. Nitrate uptake from Rhizosolenia mats is stored in internal pools. The nitrogen maybe utilized by the mats, released into surrounding waters as a way to dissipate excess energy or relieve stress, or to be remineralized by macro and microzooplankton. The Rhizosolenia play an important role in the nitrogen cycle at the photic zone with the release of nitrogen.
Ecology and Pathogenesis
Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
References
Author
Page authored by Erin Hagen and Amanda Herzog, student of Prof. Jay Lennon at Michigan State University.
