Paralytic shellfish toxins in Argopecten purpuratus and Semimytilus algosus from northern Chile

Within the framework of the Chilean molluscan shellfish safety program, blooms of Alexandrium were detected in several aquaculture sites in northern Chile. An outbreak of Alexandrium was detected in May 2006 in Mejillones Bay. Wild and cultured phytoplankton and shellfish samples from this bloom were analyzed by high performance liquid chromatography with fluorescent detection (HPLC-FD). Neither phytoplankton net tows samples nor an Alexandrium culture started from the bloom were found to contain PSP toxins at detectable levels. The shellfish, however, showed the presence of C2, GTX2, GTX3 and dcGTX2. Two new PSP episodes were recorded in June 2006 in Guanaqueros and Tongoy Bays. In these instances, shellfish samples from the two bays were analyzed by mouse bioassay and HPLC-FD, showing PSP toxicities that ranged from 27 to 34 mu g STX eq 100 g(-1) and a toxin profile mainly characterized by the presence of STX, GTX2 and GTX3. Differences between toxin profiles in Mejillones Bay and the two other locations suggest that, in the area, this kind of toxicity is probably produced by different regional populations or strains of the genus Alexandrium other than Alexandrium catenella, since the toxin profile and optimal environmental conditions for this species are noticeably different from those recorded in the proliferations from northern Chile. This paper therefore presents the first report of this kind of toxicity from an area between parallels 13 degrees 55'S and 33 degrees 5'S, comprising the subtropical zone of the southeastern Pacific Ocean. Results suggest that, as in the northern Pacific coastal area of America, PSP toxicity may be widely distributed on the southern Pacific coast.