Paralytic shellfish toxins and associated toxin profiles in bivalve mollusc shellfish from Argentina

Paralytic Shellfish Poisoning is a potentially fatal syndrome, resulting from the filter-feeding activities of marine molluscs accumulating harmful neurotoxins naturally occurring in microalgae. Outbreaks are well recognised throughout most regions of the world, but with the highest levels of toxicity to date recorded in mussels from Argentina. Whilst toxicity has been documented for selected outbreaks over the years, testing has been conducted using a mouse bioassay. Consequently there is a need to establish baseline data utilising modern chemical detection methods, which also facilitate the quantification of individual toxin analogues, giving useful data on toxin profiles as well as total sample toxicity. In this study, 151 shellfish samples harvested from the marine waters of Argentina between 1980 and 2012 were subjected to analysis by liquid chromatography with fluorescence detection, since Jan 2019 the European Union reference method for PSP determination. Total PST concentrations were found to vary enormously throughout the coastline of Argentina, with higher levels of toxins found in the central regions of Rio Negro and Chubut. Toxin profiles in terms of molar percentage of total concentrations were dominated by the gonyautoxins GTX1&4 and GTX2&3, followed by C1&2, STX and dcGTX2&3, with minor levels of other analogues previously not reported in the country. Profiles were found to vary significantly, with statistical clusters of profile types associated with a wide range of factors, including species, spatial and temporal differences, as well as likely source microalgae species and potential toxin transformation pathways. Overall application of the chemical detection method has confirmed both the significant risk to shellfish consumers in Argentina with periodic outbreaks of extremely high toxin levels and a large variability in toxin profiles relating in part to previously reported variabilities in microalgal toxin content. The study has demonstrated the potential for the method to systematically study the relationships between toxicity, toxin profile, source phytoplankton and other environmental factors.