ARE CRUSTACEANS LINKED TO THE CIGUATERA FOOD-CHAIN

Adult brine shrimp, Artemia spp., were used as an experimental organism to elucidate the role that crustacea may play in the transference of ciguatera toxins. Some ciguatera-implicated dinoflagellates were highly toxic to brine shrimp that had consumed them. Four clones of Gambierdiscus toxicus were fed in four trials at rates ranging from 2 to 480 cells per adult brine shrimp; the 24 h LD50 for the four clones were 2.8, 33.4, 41.1, and 104.5 cells per brine shrimp. Dinoflagellates Prorocentrum concavum and P. lima were also fed to adult brine shrimp, but minimal mortalities occurred at cell concentrations ranging up to 1000 cells per test animal. Tilapine cichlid (Oreochromis niloticus x O. mossambicus) young fed brine shrimp containing G. toxicus cells displayed behavioral abnormalities ranging from spiral swimming to loss of equilibrium. The present data suggest that toxins accumulated by dinoflagellate-consuming crustaceans could produce toxicity in zooplanktivorous fish species, or to detritivores in cases where dinoflagellate consumption resulted in crustacean mortalities. Field studies of the ciguatera food chain should be expanded to include examination of crustacean diets to more fully define their role in toxin transfer.