Abstract
The relationship between the ciguatoxin-producer benthic dinoflagellate Gambierdiscus and other epibenthic dinoflagellates in the Canary Islands was examined in macrophyte samples obtained from two locations of Fuerteventura Island in September 2016. The genera examined included Coolia, Gambierdiscus, Ostreopsis, Prorocentrum, Scrippsiella, Sinophysis, and Vulcanodinium. Distinct assemblages among these benthic dinoflagellates and preferential macroalgal communities were observed. Vulcanodinium showed the highest cell concentrations (81.6 × 103 cells gr−1 wet weight macrophyte), followed by Ostreopsis (25.2 × 103 cells gr−1 wet weight macrophyte). These two species were most represented at a station (Playitas) characterized by turfy Rhodophytes. In turn, Gambierdiscus (3.8 × 103 cells gr−1 wet weight macrophyte) and Sinophysis (2.6 × 103 cells gr−1 wet weight macrophyte) were mostly found in a second station (Cotillo) dominated by Rhodophytes and Phaeophytes. The influence of macrophyte’s thallus architecture on the abundance of dinoflagellates was observed. Filamentous morphotypes followed by macroalgae arranged in entangled clumps presented more richness of epiphytic dinoflagellates. Morphometric analysis was applied to Gambierdiscus specimens. By large, G. excentricus was the most abundant species and G. australes occupied the second place. The toxigenic potential of some of the genera/species distributed in the benthic habitats of the Canary coasts, together with the already known presence of ciguatera in the region, merits future studies on possible transmission of their toxins in the marine food chain.
Highlights
Ciguatera fish poisoning (CFP), the most important food-borne illness caused by fish consumption in the world, is produced by ciguatoxins (CTX) which are suggested to be transferred from epiphytic dinoflagellates of Gambierdiscus and Fukuyoa genera into the food web [1,2]
Cells of Gambierdiscus, Prorocentrum, Coolia, Sinophysis, Ostreopsis, and Vulcanodinium genera were identified in the two sampled stations but appeared in different ratios
In Cotillo, Prorocentrum, Coolia, Gambierdiscus, and Vulcanodinium were present at percentages higher than 10% (26%, 25%, 17%, and 15%, respectively) whereas Synophysis and Ostreopsis represented 10% and 8%, respectively (Figure 1B)
Summary
Ciguatera fish poisoning (CFP), the most important food-borne illness caused by fish consumption in the world, is produced by ciguatoxins (CTX) which are suggested to be transferred from epiphytic dinoflagellates of Gambierdiscus and Fukuyoa genera into the food web [1,2]. Higher toxicity has been reported, for example for G. polynesiensis in the Pacific [21,22,23], and G. excentricus in Caribbean Sea and the Canary Islands, in comparison with other species in the same regions [23,24] This emphasizes the need for implementing adequate methodologies for the unequivocal identification of species in these genera, as well as for their quantification. The methodology used was based on the parameters described by Bravo et al [26] for the five species found in the Canary Islands so far, excepting the very recently reported G. belizeanus by Tudó et al [30] These morphological traits include cell depth measurement and the shapes of the second apical (2 ) and second antapical (2””) plates, as well as the position of the Po plate. Fresh macrophytes were weighted after being manually drained just after collection
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