 <unk> shellfish poisoning ( ASP ) was first reported in eastern Canada in 1987 . It is caused by the substance domoic acid found in certain diatoms of the genus Pseudo @-@ <unk> . Bivalves can become toxic when they filter these microalgae out of the water . <unk> acid is a low @-@ molecular weight amino acid that is able to destroy brain cells causing memory loss , gastroenteritis , long @-@ term neurological problems or death . In an outbreak in the western United States in 1993 , finfish were also implicated as vectors , and seabirds and mammals suffered neurological symptoms . In the United States and Canada , a regulatory limit of 20 µg / g of domoic acid in shellfish meat is set . 
