Genus: Pseudo-nitzschia | Diatom
Monterey Bay species: P. australis, P. multiseries, P. pungens, P. fraudulenta, P. pseudodelicatissima
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Description: Cells are elongate, fusiform or rectangular in girdle view. Form chains by overlapping cell ends. Chains of 20 or more cells are not uncommon.
Cell Size: Width = 2-8um, Length = 40-175um
Interesting Facts: Many species produce domoic acid, a neurotoxin which is responsible for Amnesiac Shellfish Poisoning. In Monterey Bay, well known toxin producers P. australis and P. multiseries often form dense blooms.
Bait fish, such as anchovies and sardines, may feed on these blooms and subsequently transfer the domoic acid to their predators which include seabirds and marine mammals. The toxin has a deleterious effect on these animals, often resulting in their deaths. Interestingly, the species of Pseudo-nitzchia capable of producing domoic acid do not do so all the time. The conditions that trigger toxin production are of great interest to researchers.