Distribution and abundance of azaspiracid-producing dinophyte species and their toxins in North Atlantic and North Sea waters in summer 2018

Abstract

Representatives of the marine dinophyte family Amphidomataceae produce lipophilic phycotoxins called azaspiracids (AZA) which may cause azaspiracid shellfish poisoning (AZP) in humans after consumption of contaminated seafood. Three of the four known toxigenic species are observed frequently in the eastern North Atlantic. In 2018, a research survey was performed to strengthen knowledge on the distribution and abundance of toxigenic Amphidomataceae and their respective toxins in Irish coastal waters and in the North Sea. Species-specific quantification of the three toxigenic species (Azadinium spinosum, Azadinium poporum and Amphidoma languida) was based on recently developed qPCR assays, whose performance was successfully validated and tested with specificity tests and spike experiments. The multi-method approach of on-board live microscopy, qPCR assays and chemical AZA-analysis revealed the presence of Amphidomataceae in the North Atlantic including the three targeted toxigenic species and their respective AZA analogues (AZA-1,-2,-33,-38,-39). Azadinium spinosum was detected at the majority of Irish stations with a peak density of 8.3 x 10 4 cells L-1 and AZA (AZA-1,-2,-33) abundances up to 1,274 pg L-1. Amphidoma languida was also present at most Irish stations but appeared in highest abundance in a bloom at a central North Sea station with a density of 1.2 x 10 5 cells L-1 and an AZA (AZA-38,-39) abundances of 618 pg L-1. Azadinium poporum was detected sporadically at the Irish south coast and North Sea and was rather low in abundance during this study. The results confirmed the wide distribution and frequent occurrence of the target species in the North Atlantic area and revealed, for the first time, bloom abundances of toxigenic Amphidomataceae in this area. This emphasizes the importance of future studies and monitoring of amphidomatacean species and their respective AZA analogues in the North Atlantic.

Multiple New Strains of Amphidomataceae (Dinophyceae) from the North Atlantic Revealed a High Toxin Profile Variability of Azadinium spinosum and a New Non-Toxigenic Az. cf. spinosum

“…spinosum and Am. languida and thereby have added complementary information to the field data set on the abundance and distribution of toxigenic Amphidomataceae and their toxins to that which have been published previously [ 34 ].…”

“…Azadinium spinosum , the first identified source organism of AZA, is regarded as the most important AZA producer in Irish waters [ 18 , 25 , 34 ]. The first strains of this species isolated from Scotland [ 21 ], Denmark [ 52 ], the Shetland Islands [ 24 ], and Ireland [ 18 ] all share the same sequence data and toxin profile consisting of AZA-1, AZA-2, and AZA-33, but subsequent multiple strain studies from Norway and Argentina revealed ribotype divergence and toxin profile diversity within Az.…”

“…spinosum strains isolated from Ireland (57 strains), no single ribotype B strain was obtained, whereas B strains were the majority (seven of ten) of strains isolated from the North Sea ( Figure 15 ). This relative dominance of B strains in the North Sea was not accompanied by the detection of AZA-11 or AZA-51 in the North Sea [ 34 ], showing that Az. spinosum ribotype B strain density in the North Sea is not at a critical level.…”

“…Samples were collected during the survey (HE-516) on-board RV Heincke between 17 July and 15 August 2018 covering the South- and West coast of Ireland and the North Sea (for a full list of stations see Wietkamp et al [ 34 ]; CTD data are stored in Pangaea [ 36 ]). At each station, plankton samples were collected with 10 L Niskin bottles at 3 m, 10 m, and the depth-chlorophyll-maximum (DCM) layer.…”

“…The specific focus of this survey was to increase knowledge about the diversity and distribution of Amphidomataceae and their respective toxins in Irish coastal waters and in the North Sea. Field data of this survey, including qPCR-based abundance and distribution of toxigenic amphidomatacean species and their toxins, are presented elsewhere [ 34 ]. Next to field-sample data, on-board cell isolation and establishment of a large number of clonal amphidomatacean strains aimed at a better description of amphidomatacean diversity in the area.…”