Field observations of the dinoflagellate genus Azadinium and azaspiracid toxins in the south-west Atlantic Ocean

Abstract

Some dinoflagellate species of the genera Azadinium and Amphidoma (Amphidomataceae) produce azaspiracids (AZA), a group of toxins responsible for gastrointestinal disorders in humans following the consumption of contaminated shellfish. In this study, we investigated the diversity, distribution and abundance of Azadinium and AZA from field plankton samples collected during four oceanographic expeditions that covered an extended area of the Argentine Sea during different seasons. Scanning electron microscopy analyses indicated the presence of five Azadinium species: Az. dexteroporum, Az. luciferelloides, Az. obesum, Az. asperum and Az. cf. poporum. Azadinium-like cells were frequently found and were even an abundant component of plankton assemblages, showing a wide latitudinal distribution, from ~38 to ~55.5°S, and occurring in a wide temperature and salinity range. High cell densities (up to 154000cellsL–1) occurred in northern slope and external shelf waters during spring. AZA-2 was detected in net samples from the 20- to 200-µm fractions by tandem mass spectrometry–liquid chromatography analysis, suggesting a transfer of AZA through the food web. Our results contribute to the knowledge of the worldwide occurrence of Azadinium species and AZA, and highlight the importance of amphidomatacean species as a potential source of AZA shellfish poisoning in the south-west Atlantic Ocean.

Increase in records of toxic phytoplankton and associated toxins in water samples in the Patagonian Shelf (Argentina) over 40 years of field surveys

“…This "snapshot" monitoring system (a total of eight cruises), has augmented the records of phycotoxins. For instance, the highly abundant and multispecific blooms of Amphidomataceae (Akselman and Negri, 2012) and azaspiracids in different regions of the PSBF (Fabro et al, 2019;Tillmann et al, 2019;Guinder et al, 2020), the wide dispersion across the shelf of different potentially toxic Pseudo-nitzschia spp. and domoic acid (Almandoz et al, 2017;Guinder et al, 2018), Alexandrium catenella and A. ostenfeldii and their associated toxins (Fabro et al, 2017;Guinder et al, 2018), and Dinophysis spp.…”

“…In contrast, in spring 2015, a multispecific bloom of Amphidomataceae was observed in the same region of the Northern Patagonia Shelf and shelf-break front, and this time azaspiracid-2 (AZA-2) was detected (Tillmann et al, 2019). Although AZAs were detected in mussels in the Argentine Sea some years before their description (Turner and Goya, 2015), the first field survey planned for their detection in plankton samples only began in 2012, followed by other expeditions in 2013, 2015 and 2016 in different seasons (spring, summer and autumn) (Fabro et al, 2019;Guinder et al, 2020;Tillmann et al, 2019). Data showed that Amphidomataceae are particularly abundant in frontal areas.…”

“…Amphidomatacean strains from the North Atlantic produce a wide list of AZA-variants, with AZA-1 as one of the most frequent toxins (Tillmann, 2018). Strikingly, Argentinian strains produce only AZA-2 (e. g. Turner and Goya, 2015;Fabro et al, 2019), suggesting geographical differences in the toxic potential of the populations. For instance, Azadinium spinosum is the most important causative agent of AZA poisoning in Europe (Salas et al, 2011) but no toxic events have been registered in Argentina associated with this species (Tillmann et al, 2019) or any other Amphidomataceae.…”

Field observations on rare or unnoticed dinoflagellates from the Argentine Sea

“…However, the recent description of new dinoflagellate species (Tillmann & Akselman, 2016;Boutrup et al, 2017;Tillmann, 2018;Tillmann et al 2018;Sunesen et al, 2020b) and the finding of new records (e.g. Fabro et al, 2016Fabro et al, , 2017Fabro et al, , 2019Tillmann et al, 2016) suggest that dinoflagellate diversity in the Argentine Sea is higher than previously known.…”