Occurrence of Pseudo-nitzschia species and domoic acid in Argentina

ALMANDOZ G. O.; FABRO, E; FERRARIO, M. E.; TILLMANN, U.; KROCK, B.; CEMBELLA, A

Conferencia; 17th International Conference on Harmful Algae; 2016

The marine diatom genus Pseudo-nitzschia, the main producer of domoic acid (DA) and responsible of amnesic shellfish poisoning in humans and marine mammals, is widely distributed and presents a high species richness in Argentina. However,DA events seem to be rare and the identity of the producers remains unclear. In the present work, the distribution of Pseudonitzschia species and DA was analysed during two sampling cruises carried out along the Argentine Sea (~39-47 ºS), during summer and spring 2013. Phytoplankton composition was analysed by light and electron microscopy whereas lipophilic phycotoxins were determined by liquid chromatography coupled to tandem mass spectrometry. The genus Pseudo-nitzschia was recorded in 84 and 71% of samples collected in spring and summer, respectively, while DA was detected in only 20 and 42% of samples, respectively. Microscopic analyses revealed the presence of at least five potentially toxic species (P. australis, P. brasiliana, P. fraudulenta, P. pungens, P. turgidula), plus P. dolorosa, P. lineola, P. turgiduloides and unidentified specimens of the P. pseudodelicatissima complex. In the northern area and during summer, DA was detected in samples with only P. brasiliana (0.45-0.56 pg DA cell l-1), a species recorded for the first time in the Argentine Sea. However, DA usually co-occurred with more than one species, from which P. australis was the most highly correlated. By contrast, high concentrations of P. fraudulenta, P. pungens and P. turgidula did not match with DA occurrence. Additional field and culture studies are needed to elucidate DA production in this region.