Morphological, Toxicological, and Biochemical Characterization of Two Species of Gambierdiscus from Bahía de La Paz, Gulf of California

We describe five new isolates of two <i>Gambierdiscus</i> species from Bahía de La Paz in the southern Gulf of California. Batch cultures of <i>Gambierdiscus</i> were established for morphological characterization using light microscopy (LM) and scanning electron microscopy (SEM). Pigment and amino acid profiles were also analyzed using high-performance liquid chromatography (HPLC-UV and HPLC-DAD). Finally, toxicity (CTX-like and MTX-like activity) was evaluated using the <i>Artemia salina</i> assay (ARTOX), mouse assay (MBA), marine fish assay (MFA), and fluorescent receptor binding assay (fRBA). These strains were identified as <i>Gambierdiscus</i> cf. <i>caribaeus</i> and <i>Gambierdiscus</i> cf. <i>carpenteri.</i> Toxicity for CTX-like and MTX-like activity was confirmed in all evaluated clones. Seven pigments were detected, with chlorophyll <i>a</i>, pyridine, Chl2, and diadinoxanthin being particularly noteworthy. For the first time, a screening of the amino acid profile of <i>Gambierdiscus</i> from the Pacific Ocean was conducted, which showed 14 amino acids for all strains except histidine, which was only present in <i>G.</i> cf. <i>caribeaus</i>. We report the presence of <i>Gambierdiscus</i> and <i>Fukuyoa</i> species in the Mexican Pacific, where ciguatera fish poisoning (CFP) cases have occurred.