Marine Biotoxins in Whole and Processed Scallops from the Argentine Sea.

Harmful algal blooms are an increasing worldwide threat to the seafood industry and human health as a consequence of the natural production of biotoxins that can accumulate in shellfish. In the Argentine Sea, this has been identified as an issue for the offshore fisheries of Patagonian scallops (Zygochlamys patagonica), leading to potentially harmful effects on consumers. Here we assess spatial and temporal patterns in marine biotoxin concentrations in Patagonian scallops harvested in Argentinian waters between 2012-2017, based on analyses for paralytic shellfish toxins, lipophilic toxins, and amnesic shellfish toxins. There was no evidence for concentrations of lipophilic or amnesic toxins above regulatory acceptance thresholds, with trace concentrations of pectenotoxin 2, azaspiracid 2 and okadaic acid group toxins confirmed. Conversely, paralytic shellfish toxins were quantified in some scallops. Gonyautoxins 1 and 2 dominated the unusual toxin profiles (91%) in terms of saxitoxin equivalents with maximum concentrations reaching 3985 µg STX eq/kg and with changes in profiles linked in part to seasonal changes. Total toxin concentrations were compared between samples of the adductor muscle and whole tissue, with results showing the absence of toxins in the adductor muscle confirming toxin accumulation in the digestive tracts of the scallops and the absence of a human health threat following the processing of scallop adductor meat. These findings highlight that paralytic shellfish toxins with an unusual toxin profile can occur in relatively high concentrations in whole Patagonian scallops in specific regions and during particular time periods, also showing that the processing of scallops on board factory ships to obtain frozen adductor muscle is an effective management process that minimizes the risk of poisonings from final products destined for human consumption.

Variability of Amnesic Shellfish Toxin and Pseudo-nitzschia occurrence in bivalve molluscs and water samples-Analysis of ten years of the official control monitoring programme.

As the official control laboratory for marine biotoxins within Great Britain, the Centre for Environment, Fisheries and Aquaculture Science, in conjunction with the Scottish Association for Marine Science, has amassed a decade's worth of data regarding the prevalence of the toxins associated with Amnesic Shellfish Poisoning within British waters. This monitoring involves quantitative HPLC-UV analysis of shellfish domoic acid concentration, the causative toxin for Amnesic Shellfish Poisoning, and water monitoring for Pseudo-nitzschia spp., the phytoplankton genus that produces domoic acid. The data obtained since 2008 indicate that whilst the occurrence of domoic acid in shellfish was generally below the maximum permitted limit of 20 mg/kg, there were a number of toxic episodes that breached this limit. The data showed an increase in the frequency of both domoic acid occurrence and toxic events, although there was considerable annual variability in intensity and geographical location of toxic episodes. A particularly notable increase in domoic acid occurrence in England was observed during 2014. Comparison of Scottish toxin data and Pseudo-nitzschia cell densities during this ten-year period revealed a complex relationship between the two measurements. Whilst the majority of events were associated with blooms, absolute cell densities of Pseudo-nitzschia did not correlate with domoic acid concentrations in shellfish tissue. This is believed to be partly due to the presence of a number of different Pseudo-nitzschia species in the water that can exhibit variable toxin production. These data highlight the requirement for tissue monitoring as part of an effective monitoring programme to protect the consumer, as well as the benefit of more detailed taxonomic discrimination of the Pseudo-nitzschia genus to allow greater accuracy in the prediction of shellfish toxicity.

Variability of paralytic shellfish toxin occurrence and profiles in bivalve molluscs from Great Britain from official control monitoring as determined by pre-column oxidation liquid chromatography and implications for applying immunochemical tests.

As the official control monitoring laboratory in Great Britain for the analysis of marine biotoxins in shellfish, Cefas have for the past five years conducted routine monitoring for paralytic shellfish poisoning toxins (PST) using a non-animal alternative method to the mouse bioassay reference method; a refined version of the AOAC 2005.06 pre-column oxidation liquid chromatography method. Application of this instrumental methodology has enabled the generation of data not only on the occurrence and magnitude of PST events, but also the quantitation and assessment of different PST profiles. Since implementation of the method in 2008, results have shown huge variabilities in the occurrence of PSTs, with large spatial and temporal variabilities around the coastline. Mean PST profiles were not found to correlate either with total PST content of the shellfish, the year of sampling or with a few notable exceptions, the shellfish species. Toxin profiles were found to fall into one of four distinct profile types, with one relating solely to the exclusive presence of decarbamoyl toxins in surf clams. The other profile types contained variable proportions of gonyautoxins, N-sulfocarbamoyl toxins, neosaxitoxin and saxitoxin. While some indications of geographical repeatability were noted, this was not observed for all profile types. Consequently, the application of rapid immunochemical testing methods to end product testing would need to be considered carefully given the large differences in PST congener cross-reactivities.