UC San Diego

The first occurrence of the neurotoxin domoic acid (DA) in Humboldt squid (Dosidicus gigas) during a toxic Pseudo-nitzschia bloom in the Southern California Bight is reported. Bloom levels of cells with in the Pseudo-nitzschia delicatissima group were detected on 6 July 2009 at 4 nearshore collection sites in the Southern California Bight (Scripps Pier, Newport Pier, Goleta Pier and Sterns Wharf). Particulate DA was detected in all of these locations, except for Newport Pier. Stranded Humboldt squid were found south of the Scripps pier 5 days after the toxic bloom was detected. DA was measured using ELISA and low DA concentrations were detected in the stomach or mantle tissue of the stranded specimens. Stomach content analysis indicated that possible DA vectors to Humboldt squid included both pelagic (Pacifc hake, Merluccius products, and Pacific sardine, Sardinops sagax) and nearshore (pile surfperch, Damalichthys vacca, and shiner surfperch, Cymatogaster aggregata) fish species. Although low DA levels were detected in stranded squid specimens, neurological symptoms of DA toxicity were not observed and low DA concentrations alone may not have been the cause of the stranding. Further studies should focus on DA toxic effects in D. gigs to verify whether this pelagic predator can be affected by a toxin frequently detected in pelagic ecosystems influenced by the California Current System.