Abstract

MANCERA-PINEDA, JOSÉ ERNESTO; MONTALVO-TALAIGUA, MARCIAL  and  GAVIO, BRIGITTE. Potentially toxic Dinoflagellates associated to drift in San Andres Island, International Biosphere Reservation - Seaflower. Caldasia [online]. 2014, vol.36, n.1, pp.139-156. ISSN 0366-5232.  https://doi.org/10.15446/caldasia.v36n1.43896.

To assess the composition and abundance of potentially toxic dinoflagellates associated to drift on San Andres island, we selected seven sampling sites along the northern and eastern side of the island. During the wind season, we collected drift samples, identified the main substrates to species, and submerged them in 1:1 filtered seawater and Transeau solution. After shaking to remove the dinoflagellates, we sieved through an 80 µm screen and analyzed the detached dinoflagellates under an optical microscope. We found five substrates, two seagrass species and three macroalgae. Associated to these substrates, we identified twelve dinoflagellates species, ten of which are reported as toxic and are known to produce diarrhea, paralysis and ciguatera, syndromes reported in San Andrés and other Caribbean places where their frequency is apparently increasing. The dinoflagellate abundance presented strong variation with maximum average values (±SD) of 15354±15749 cel. /g of substrate dry weight. Five of the dinoflagellates associated to drift are new records for the island. We did not found significant differences in diversity of benthic dinoflagellates between drift and seagrass and macroalgae beds; however, the abundance was much higher in drift. The results showed that drift is a very important substrate for potentially toxic dinoflagellates and, considering its buoyant nature, it may represent one of the main dispersion vectors for these species on the island. To mitigate the effect of intoxication events on public health, fisheries and tourism, it is necessary to design a floating organic material management plan, improve the understanding of drift composition and its temporal dynamics, as well as to monitor associated toxins and pursue collection and treatment mechanisms of the floating biomass.

Keywords : Potentially toxic dinoflagellates; drift; ciguatera; San Andrés Island; Caribbean.

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