Paralytic Shellfish Toxins Occurrence in Non-Traditional Invertebrate Vectors from North Atlantic Waters (Azores, Madeira, and Morocco)

Abstract

Paralytic shellfish toxins (PSTs) are potent alkaloids of microalgal and cyanobacterial origin, with worldwide distribution. Over the last 20 years, the number of poisoning incidents has declined as a result of the implementation of legislation and monitoring programs based on bivalves. In the summer of 2012 and 2013, we collected a total of 98 samples from 23 different species belonging to benthic and subtidal organisms, such as echinoderms, crustaceans, bivalves, and gastropods. The sampling locations were Madeira, São Miguel Island (Azores archipelago), and the northwestern coast of Morocco. The samples were analyzed using post-column oxidation liquid chromatography with a fluorescence detection method. Our main goal was to detect new vectors for these biotoxins. After reporting a total of 59 positive results for PSTs with 14 new vectors identified, we verified that some of the amounts exceeded the limit value established in the EU. These results suggest that routine monitoring of saxitoxin and its analogs should be extended to more potential vectors other than bivalves, including other edible organisms, for a better protection of public health.

First Report of Paralytic Shellfish Toxins in Marine Invertebrates and Fish in Spain

“…In the United Kingdom, the possible link between stranded starfish containing high PSTs levels with cases of PSP intoxication in dogs was suggested [ 27 ]. Other authors [ 12 ] published the presence of PSTs in several starfish samples collected during 2012–2013 in Madeira and Azores islands. They suggested these non-traditional invertebrate vectors could play a role in PSP episodes.…”

“…This is the case of the EU where Regulation (EC) No 853/2004 sets the maximum PSTs concentrations in bivalve mollusks, echinoderms, tunicates and marine gastropods [ 10 ]. In recent years, several papers reported, for the first time, the presence of PSTs in non-traditional vectors in different European countries [ 11 , 12 , 13 ]. However, to our knowledge, studies describing the presence of PSTs on several non-bivalve mollusk marine invertebrate vectors have not been conducted in Spain.…”

Multiple New Paralytic Shellfish Toxin Vectors in Offshore North Sea Benthos, a Deep Secret Exposed

“…Consequently, toxin prevalence data has, to date, typically focussed on a restricted range of taxa, the majority of which are bivalve molluscs, with occasional reference to marine gastropods [ 52 , 64 ] and crustaceans [ 65 , 66 , 67 , 68 ]. While, the occurrence of PST in other marine invertebrates is less well-understood, there has been an increasing number of reports of PSTs in echinoderms, gastropods and barnacles [ 2 , 53 , 58 , 69 ]. Even less frequently, with the exception of offshore scallop harvests [ 70 ], findings of toxins have been reported in more offshore benthic samples.…”

“…Selective retention/elimination is highly unlikely here, given the extremely low relative proportions of dcSTX present in toxin-producing Alexandrium species found in the UK. Consequently, without the presence of enzymatic biotransformation, there is the potential for decarbamoylation to be triggered by other mechanisms relating to the conditions within the benthos at the bottom of the North Sea at depths of 30 m–170 m. Previous work has also highlighted varying toxin profiles in marine invertebrates in different geographical locations [ 54 , 58 ]. Silva et al 2018 [ 58 ] focussed on three geographical locations with each group of samples showing high proportions of the decarbomyl toxins dcGTX2&3, whilst Silva et al 2013 [ 54 ] described high dcSTX content in some gastropods and bivalves, which could evidence enzymatic change in those environments.…”

“…Furthermore, the invertebrate species that were implicated were also unexpected. Whilst the accumulation of PSTs in marine organisms other than bivalve molluscs is well-documented [ 2 , 32 , 49 , 50 , 51 , 52 , 53 , 54 ], PSTs presence in starfish is rarely described [ 53 , 55 , 56 , 57 , 58 ], with toxicity generally far lower than the 14,000 µg STX eq./kg described in England. The presence of highly toxic starfish in the UK benthos in the winter, in a geographic location where PSTs are rarely, if ever, seen in shellfish, with a toxin profile unlike any currently known domestic algal PST producer, required further investigation to help disseminate which/ if any other organisms are implicated and the geographical range of the toxic benthos.…”