Seasonal persistence of resting cyst toxicity in the dinoflagellate Gonyaulax tamarensis var. excavata.

Resting cysts collected in the autumn from bottom sediments were stored in the laboratory, in the dark at 4 degrees C, through the winter. Over a six month period, toxicity of the stored resting cysts was compared with toxicity of cysts from freshly-collected sediments. Resting cysts retained toxin over the winter months. Toxin levels show an apparent rise. Toxicity measurements of cysts from sediment samples kept in the laboratory reflect in situ levels.