First detection of azaspiracids in mussels in North West Africa

Journal of Shellfisheries Research, Dec, 2006 by H. Taleb, P. Vale, R. Amanhir, A. Benhadouch, R. Sagou, A. Chafik

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DISCUSSION

This study reports for the first time the presence of azaspiracids in the NW African coast, and is the first time AZAs are reported in shellfish from such low latitude (32[degrees]50'904N, 8[degrees]53'500W) and outside Europe. The presence of AZA2 in shellfish from the south coast of Portugal was previously suspected, but the low levels found of the suspect compounds did not allow their unambiguous confirmation, mainly because that study used whole flesh (Vale 2004). According to Hess et al. (2005), these toxins are on average circa 5 times more concentrated in DG, compared with the whole mussel.

The simultaneous presence of DSP and AZP toxins may occur in Moroccan mussels, but maximal concentrations of these two distinct toxin families are separated in time. Evidence from Irish mussels points also that contamination with AZP may follow contamination with DSP (Clarke et al. 2006), but appearance of AZP before the rise in DSP toxins may also occur (Hess et al. 2002). Because the species hypothesized to produce AZAs is known to be heterotrophic, its growth might depend on the appearance of conditions that favor the blooming of certain algae species necessary for predation, amongst which also proliferate the DSP producers.

In the Atlantic Moroccan coast, the occurrence of AZP seems to be recurrent, and maximal levels may take place over the summer, although other seasons of the year were not studied yet for the presence of AZP. After the launching of the lipophilic toxin monitoring along the Moroccan coast by mouse bioassay (MBA), the recurrence of lipophilic toxin outbreaks in the Atlantic coast was recorded during the summer time almost every year since 1999, but in the Mediterranean coast occurrence of this type of toxins is rare (Taleb, 2005). For the moment, at least two families of lipophilic compounds are implied in the observed mouse bioassay toxicity. So far, these are the most relevant families of toxins for public health, as other families, such as yessotoxins and pectenotoxins, do not seem to be relevant for human health because of their low oral potency (Anonymous 2004).

The toxin profiles found in European shellfish (hepatopancreas) and plankton samples have been dominated by AZA1 (James et al. 2002a, James et al. 2003a, Magdalena et al. 2003). However, AZA3 has been reported to be the most abundant toxin in meat samples with the hepatopancreas excised (James et al. 2002b). Although variations in toxin profile have been observed, the results reported here of AZA2 dominance might point to a difference in the phytoplankton-producing species. Indeed, the finding of AZAs at such low latitudes may raise the question if more than one species is involved in AZA production and also concerns of a more universal distribution of AZAs than previously believed.

LITERATURE CITED

Anonymous. 2004. Report of the joint FAO/IOC/WHO ad hoc expert consultation on biotoxins in bivalve molluscs. Oslo, Norway, Sept. 26-30, 2004.

Clarke D., L. Devilly, T. McMahon, M. O'Cinneide, J. Silke, S. Burrell, O. Fitzgerald, P. Hess, J. Kilcoyne, M. McElhinney, J. Ronan, R. Gallardo Salas, B. Gibbons, M. Keogh, M. McCarron, S. O'Callaghan & B. Rourke. 2006. A review of shellfish toxicity monitoring in Ireland and review of management cell decisions for 2005. In: Proceedings of the 6th Irish Shellfish Safety Scientific Workshop. Marine Institute, Marine Environment & Health Series, n[degrees]23. pp. 22-34.