Monterey Bay Aquarium Research Institute
Marine Botany

Pseudo-nitzschia Toxins

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Amnesic Shellfish Poisoning (ASP)

Amnesic Shellfish Poisoning is a neurological disorder caused by the excitatory neurotransmitter domoic acid (glutamate analog). Domoic acid is produced by some species (i.e. P. australis, multiseries, delicatissima, pseudodelicatissima, seriata) within the genus Pseudo-nitzschia. Harmful algal blooms that include these toxic species can be found in coastal regions world-wide. ASP is usually brought on by the ingestion of shellfish (e.g. mussels) that have fed upon diatom blooms that include toxic species of Pseudo-nitzschia. The shellfish, in this manner, act as vectors that transfer the domoic acid to humans (and in higher amounts since they feed on the blooms and concentrate the domoic acid).


  • 1987, Prince Edward Island, Canada: many died and over 100 became ill after consuming blue mussels that had fed on diatom blooms
  • 1987-1991, Eastern North America: Domoic acid found in shellfish
  • September 1991, Monterey Bay: death of brown pelicans and cormorants coincided with a large bloom of Pseudo-nitzschia australis (that was concentrated by anchovies and then eaten by the pelicans and cormorants)
  • November 1991, Washington & Oregon: shellfish & crab harvesting close
  • Study & Progress

    Early detection of Domoic Acid outbreaks can be achieved by successful identification,quantification, and mapping of Pseudo-nitzschia found in phytoplankton blooms throughout the world. More specifically, the samples of Pseudo-nitzschia need to be classified as toxic or non-toxic. Traditionally, this identification was both time consuming and expensive (SEM and expert taxonomist needed), but more expedient methods have been developed in recent years [See Identification for more information on identification methods!]. Besides identification, more information is necessary with respect to its potential grazers (and thus vectors of domoic acid), contribution to phytoplankton biomass, environmental constraints, life cycle, and capacity to produce domoic acid. The importance of this research will aid in maintaining both public and economic health.

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    copyright Jennifer Shin 1999.