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 which is 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 degrees Celsius.[1] Some Nitzchia species are also extremophiles by dent of tolerance to high salinity; for example, some halophile species of Nitzchia are found in the Makgadikgadi Pans in Botswana.[2]