Variability and profiles of lipophilic toxins in bivalves from Great Britain during five and a half years of monitoring: azaspiracids and yessotoxins.

•AZA and YTX group toxin results from over 5 years of monitoring in bivalves.•Large interannual variation in AZA occurrences.•Winter occurrences of AZAs noted in some years.•AZA1 the most dominant in the AZA group.•YTXs present mainly during summer months in focused areas.•Protoceratium reticulatum as the likely source of YTXs in British bivalves.