Ciguatoxicity of Gambierdiscus and Fukuyoa species from the Caribbean and Gulf of Mexico

Abstract

Dinoflagellate species belonging to the genera Gambierdiscus and Fukuyoa produce ciguatoxins (CTXs), potent neurotoxins that concentrate in fish causing ciguatera fish poisoning (CFP) in humans. While the structures and toxicities of ciguatoxins isolated from fish in the Pacific and Caribbean are known, there are few data on the variation in toxicity between and among species of Gambierdiscus and Fukuyoa. Quantifying the differences in species-specific toxicity is especially important to developing an effective cell-based risk assessment strategy for CFP. This study analyzed the ciguatoxicity of 33 strains representing seven Gambierdiscus and one Fukuyoa species using a cell based Neuro-2a cytotoxicity assay. All strains were isolated from either the Caribbean or Gulf of Mexico. The average toxicity of each species was inversely proportional to growth rate, suggesting an evolutionary trade-off between an investment in growth versus the production of defensive compounds. While there is 2- to 27-fold variation in toxicity within species, there was a 1740-fold difference between the least and most toxic species. Consequently, production of CTX or CTX-like compounds is more dependent on the species present than on the random occurrence of high or low toxicity strains. Seven of the eight species tested (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, Gambierdiscus ribotype 2, G. silvae and F. ruetzleri) exhibited low toxicities, ranging from 0 to 24.5 fg CTX3C equivalents cell-1, relative to G. excentricus, which had a toxicity of 469 fg CTX3C eq. cell-1. Isolates of G. excentricus from other regions have shown similarly high toxicities. If the hypothesis that G. excentricus is the primary source of ciguatoxins in the Atlantic is confirmed, it should be possible to identify areas where CFP risk is greatest by monitoring only G. excentricus abundance using species-specific molecular assays.

Ciguatoxin Occurrence in Food-Web Components of a Cuban Coral Reef Ecosystem: Risk-Assessment Implications

“…Furthermore, 10 other C-CTX analogues or isomers with different mass have also been isolated [16], but their structures have not yet been elucidated. The structure of the toxin precursors at producers (trophic level 1) in the Caribbean has not yet been confirmed, although CTX-like activity was demonstrated by biological cytotoxicity assay in species including G. carolinianus or G. excentricus and ranged from 0.02 to 469 fg CTX3C (aka P-CTX3C) equivalents per cell [21]. In contrast, marine first-order consumers (trophic level 2) of the Caribbean region have never been analyzed for their CTX contents.…”

Species‐specific PCR assays for Gambierdiscus excentricus and Gambierdiscus silvae (Gonyaulacales, Dinophyceae)

“…, Litaker et al. ). Several of those studies have shown that G. excentricus and G. silvae are the most toxic species in the Caribbean and eastern Atlantic (Fraga et al.…”

“…The G. excentricus isolates were obtained from samples collected at Pulley Ridge reef (N 25°53.131, W 83°36.368; Pulley Ridge Gam2 = Pulleys Ridge in Litaker et al. , Pisapia et al. ) located 160 km west of the Tortugas Ecological Reserve in the Northeastern Gulf of Mexico and from the Bahamas (N 26°38.849, W 78°04.839; Bahamas Gam5 = BahamaGam5 in Litaker et al.…”

“…) located 160 km west of the Tortugas Ecological Reserve in the Northeastern Gulf of Mexico and from the Bahamas (N 26°38.849, W 78°04.839; Bahamas Gam5 = BahamaGam5 in Litaker et al. ). One isolate of G. silvae was obtained from Curacao (N 12°05.173, W 68°54.004; Curacao Gam11).…”

“…To Litaker et al 2017). One isolate of G. silvae was obtained from Curacao (N 12°05.173, W 68°54.004; Curacao Gam11).…”