Global Distribution of Ciguatera Causing Dinoflagellates in the Genus Gambierdiscus
R. Wayne Litaker1, Mark W. Vandersea1, Maria A. Faust2, Steven R. Kibler1, Amy Nau1, Mireille
Chinain3, Michael J. Holmes4, William C. Holland1 and Patricia A. Tester1
1
NOS/NOAA, Center for Coastal Fisheries and Habitat Research, Beaufort, North Carolina
Department of Botany, Smithsonian Institution, Suitland, Maryland
3
Laboratoire Des Micro-Algues Toxiques, Institut Louis Malardé, Tahiti
4
Tropical Marine Science Institute, National University of Singapore, Singapore
2
Ciguatera fish poisoning (CFP) results from the bioaccumulation of toxins produced by
dinoflagellates species in the genus Gambierdiscus. Globally, CFP is the most common nonbacterial food poisonings reported. Currently, little is known about the distribution of individual
Gambierdiscus species or their relative toxicities. This poster presents an LSU rDNA phylogeny
supporting the existence of at least 12 different Gambierdiscus species along with a map
documenting that unequal distributed of these species between the Atlantic and Pacific Oceans.
Isolates of Gambierdiscus belizeanus, G. carolinianus, G. ruetzleri, and Gambierdiscus sp.
ribotypes 1 and 2 all came from the Atlantic, whereas isolates of G. pacificus, G. polynesiensis,
G. toxicus, and G. yasumotoi were all from the Pacific. G. caribaeus and G. carpenteri were the
exceptions being widely distributed throughout both basins. Interestingly, the unequal species
distributions noted in this study paralleled known structural differences in the dominant
ciguatoxins recovered from Atlantic and Pacific fishes. Jointly, these data suggest that Atlantic
species may produce a suite of toxins different from those synthesized by their Pacific
counterparts. A literature survey further showed that the overall densities of Gambierdiscus in
the Atlantic and Pacific were similar and that both regions contained isolates whose toxicity
ranged from below detection to extremely high. Analysis of field collected cells showed
variations in toxicity were equally large. These data imply that the toxin levels in a given
location depend on which Gambierdiscus species or strains present as well as overall cell
densities. This may account for why significant increases in Gambierdiscus abundance
sometime fail to produce a subsequent CFP event. What these laboratory studies could not
adequately resolve was whether the among isolate variation in toxicity was due more to inherent
differences in the toxicity among Gambierdiscus species, to differences among strains, or to
both. The reason is a majority of the toxicity studies on Gambierdiscus isolates were undertaken
when only one species had had been described. Data from the limited number of isolates whose
identity was unambiguously established showed that among species toxicities varied by at least
100 fold and that environmental factors likely modulate toxicity to a lesser degree (~2 to 9 fold
range). Only two comparable estimates for between isolate variations in toxicity were available
precluding similar range estimates. Whether the variation in toxicity is due more to species or
strain differences has profound implication of our ability to develop an effective early warning
system for CFP.