Seasonal and inter-annual changes in okadaic acid and Dinophysis toxins profiles in bivalve molluscs from Great Britain

Cefas has conducted official control testing of bivalve molluscs from Great Britain for marine biotoxins for over a decade and lipophilic toxins (LTs) have been quantified by liquid chromatography tandem mass spectrometric... [ view full abstract ]

Cefas has conducted official control testing of bivalve molluscs from Great Britain for marine biotoxins for over a decade and lipophilic toxins (LTs) have been quantified by liquid chromatography tandem mass spectrometric (LC-MS/MS) method since 2011. Here we aim to present results for Okadaic acid (OA), Dinophysistoxin 1 (DTX1), Dinophysis toxin 2 (DTX2) and their respective ester forms in shellfish obtained through official control testing between July 2011 and December 2016.

The temporal pattern of OA group toxins remained similar each year, however the abundance and intensity varied considerably. The ratios between OA, DTX1 and DTX2 were examined and three profiles identified. There were some inter-annual differences in profiles in certain regions, with DTX2 being absent between 2011 - 2013, but present in subsequent years. A seasonal change in profiles was also noted in some geographical areas, where higher proportions of OA at the beginning of the season were replaced by higher proportions of DTX2 in late summer and autumn. Finally, the ratios between free OA group toxins and their respective esters were examined and found to be species dependent.

For the first time, the OA group toxin occurrences in Great Britain and changes in their profiles during and between the seasons will be assessed for over five consecutive years. The knowledge shall lay down the foundation for further studies examining the driving forces behind such a dynamic phenomenon, and hopefully will lead to better public health protection in the future.