Dynamic Model of the Flux of Domoic Acid, a Neurotoxin, through a Mytilus edulis Population

Abstract

A one-compartment computer simulation model was developed to quantify and characterize the accumulation of the neurotoxin domoic acid in blue mussel (Mytilus edulis) in Cardigan Bay, Prince Edward Island, Canada. Comparison of simulation results with field abundances of Nitzschia pungens f. multiseries Hasle, a diatom implicated in the production of domoic acid, and with measurements of domoic acid within Nitzschia cells indicates that the rate of accumulation of domoic acid in mussel tissue during peak bloom conditions may involve unexpected physiological feedback processes. At extremely high concentrations of toxin (> 300 ppm) observed in toxic Mytilus episodes off eastern Prince Edward Island in 1987 during the peak of Nitzschia bloom, the depuration of domoic acid seemed to be suppressed; this may have been responsible for the observed abnormal buildup of toxin in the mussels. In 1989 the amount of domoic acid produced by N. pungens was slightly lower, but the levels of domoic acid in Mytilus were much less than in 1987. These results suggest that a crucial factor in prediction of high levels of domoic acid in mussels may be identification of changes in their physiology and metabolism which suppress depuration rates.