Results from monitoring of marine biotoxins in bivalve molluscs during harvesting on the Swedish Skagerrak coast, 2014-2016

Monitoring of marine biotoxins in bivalve molluscs and occurrence of marine biotoxin producing algae in production areas is carried out by The National Food Agency in Sweden. Production areas for harvesting of bivalve molluscs... [ view full abstract ]

Monitoring of marine biotoxins in bivalve molluscs and occurrence of marine biotoxin producing algae in production areas is carried out by The National Food Agency in Sweden. Production areas for harvesting of bivalve molluscs are located along the Swedish Skagerrak coast. Four commercial species of bivalves are harvested; blue mussel (Mytilus edulis), flat oyster (Ostrea edulis) pacific oyster (Crassostrea gigas) and cockles (Cerastoderma edule). The monitoring program includes the marine biotoxins Diarrhetic Shellfish Toxins (DST), Pecteno Toxins (PTX), Azaspiracidic acid (AZA), Yessotoxins (YTX), Paralytic Shellfish Toxins (PST) and Amnesic Shellfish Toxins (AST) and also harmful algae. Data from 2014 to 2016 show high variability in concentrations of toxins between bivalve species. DST was commonly observed in M. edulis and rarely in other bivalves. Concentrations above the regulatory limit were almost exclusively observed in M. edulis. and only during shorter periods. DST in bivalves is connected to the presence of Dinophysis spp.. Concentrations of YTX did not exceed the regulatory limit at any time though the toxin was present throughout most of the period. Levels of PST and AST above the regulatory limit were observed only in a few occasions. Unusually high abundances of Alexandrium spp. were observed during a PST event in 2014. In production areas where several species were harvested simultaneously the presence of marine biotoxins were compared between species. The results indicate that blue mussels possibly could be used as an indicator species of certain toxins in these areas.