Nitzschia

Nitzschia is a common pennate marine and freshwater diatom. In the scientific literature, this genus, named after Christian Ludwig Nitzsch, is sometimes referred to incorrectly as Nitzchia, and it has many species described, which all have a similar morphology. In its current circumscription, Nitzschia is paraphyletic.

==Occurrence== Nitzschia is found mostly in colder waters, and is associated with both Arctic and Antarctic polar sea ice, where it is often found to be the dominant diatom. Nitzschia includes several species of diatoms known to produce the neurotoxin known as domoic acid, a toxin responsible for the human illness called amnesic shellfish poisoning. The species N. frigida is found to grow exponentially even at temperatures between −4 and −6 °C. Some Nitzschia species are also extremophiles by dint of tolerance to high salinity; for example, some halophilic species of Nitzschia are found in the Makgadikgadi Pans in Botswana.