Saxitoxin

Saxitoxin is a potent neurotoxin produced by dinoflagellates such as Gonyaulax catenella and G. tamarensis. It causes paralytic shellfish poisoning in people who eat filter-feeding bivalves, clams, mussels, and oysters, that have accumulated the toxin. Cooking does not destroy it, so shellfish-growing waters are monitored and harvesting is closed during toxic algal blooms. Symptoms include numbness and, in severe cases, respiratory paralysis. Monitoring programmes test shellfish flesh regularly during bloom seasons. Consumers should heed harvesting closures. Public health depends on vigilant monitoring of shellfish waters.