Pseudo-nitzschia is a marine planktonic diatom genus containing some species capable of producing the neurotoxin domoic acid (DA), which is responsible for the neurological disorder known as amnesic shellfish poisoning (ASP). Currently, there are 46 known species, 19 of which are known to produced DA (see Known Species). It was originally hypothesized that only dinoflagellates could produce harmful algal toxins, but a deadly bloom of Pseudo-nitzschia occurred in 1987 in the bays of Prince Edward Island, Canada, and lead to an outbreak of ASP. Over 100 people were affected by this outbreak after consuming contaminated mussels; three people died. Blooms have since been characterized in coastal waters worldwide and have been linked to increasing marine nutrient concentrations.