Tetrodotoxins Occurrence in Non-Traditional Vectors of the North Atlantic Waters (Portuguese Maritime Territory, and Morocco Coast)

Abstract

Tetrodotoxin (TTX) is a potent alkaloid typically from tropical ecosystems, but in the last decade its presence has been more pronounced in the temperate waters of the Atlantic. In its last scientific opinion, the European Food Safety Authority (EFSA) stressed the need for data regarding TTX prevalence in European waters. To address EFSA's concerns, benthic organisms such as mollusks, crustaceans, echinoderms and fish with different feeding habits were collected along the Portuguese continental coast, islands (São Miguel, Azores, and Madeira) and the northwestern Moroccan coast. A total of 165 samples were analyzed by ultra high performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) and ultra high performance chromatography mass spectrometry (UHPLC-MS/MS). Geographical tendencies were detected as follows, by descending order: S. Miguel Island (Azores), Moroccan coast, Madeira Island and Portuguese continental coast. The toxin amounts detected were significant, above the Dutch limit value established in 2017, showing the importance and the need for continuity of these studies to gain more knowledge about the prevalence of these toxins, unraveling new vectors, in order to better assess human health risk. This work represents a general overview of new TTX bearers (7) most of them in gastropods (Patella depressa, Nucella lapillus, Onchidella celtica and Aplysia depilans), followed by echinoderms (Echinus esculentus and Ophidiaster ophidianus) and puffer fish Sphoeroides marmoratus.

Keywords: North Atlantic Waters; new vectors; tetrodotoxin.

Figure 1

Location of the sampling points: (A) Portuguese continental coast: 1, Esposende; 2, Póvoa do Varzim; 3, Angeiras; 4, Memória; 5, Pedra de Jacó; 6, Pêlo Negro; 7, Valadares; 8, Ovar; 9, Porto Côvo; 10, Camilo; 11, Luz. (B) Madeira Island coast: 1, Caniçal and 2, Reis Magos. (C) São Miguel Island coast, Azores archipelago: 1, Cruzeiro; 2, Mosteiros; 3, Étar de Ponta Delgada; 4, São Roque; 5, Lagoa; 6, Caloura. (D) Northwestern Moroccan coast: 1, Casablanca Corniche; 2, El Jadida Haras; 3, El Jadida Sâada; 4, Sidi Bouzid; 5, Mrizika; 6, Oualidia.

Figure 2

Multiple reaction monitoring (MRM) chromatogram obtained in positive mode of tetrodotoxin (TTX) standard.

Figure 3

Chromatogram and mass spectrum of TTX standard. (A) Chromatogram of TTX and 4-epiTTX obtained by PIS. (B) Mass fragmentation pattern of TTX and 4-epiTTX. (C) Chromatogram of 11-deoxyTTX obtained by PIS. (D) Mass fragmentation pattern of 11-deoxyTTX. (E) Chromatogram of 4,9-anhydroTTX obtained by PIS. (F) Mass fragmentation pattern of 4,9-anhydroTTX.