Ecology of Toxic Dinoflagellates from the Caribbean Sea

Résumé du livre

The association of three toxic species of dinoflagellates (Gambierdiscus toxicus, Prorocentrum concavum and P. mexicanum) with selected species of macroalgae (Chaetomorpha linum, Dictyota dichotoma and Turbinaria turbinata) was examined in the Virgin Islands. Maximum concentrations of each of these dinoflagellates were 1.5 x 10^4, 9.5 x 10^4 and 1.5 x 10^6 cells/g f.w. of macroalgae, respectively. Relationships between these dinoflagellates and macroalgae were studied in bacterized and bacteria-free cultures, by enriching culture media with aqueous extracts of macroalgae and soil. In bacterized cultures, Chaetomorpha and soil extracts significantly increased growth rates and cell yields of G. toxicus. All extracts stimulated the growth of P. concavum, but extracts of macroalgae inhibited the growth of P. mexicanum. This indicates that the dinoflagellate-macroalgal association is differentially beneficial to various dinoflagellate species. Under bacteria-free conditions, the growth of P. concavum was significantly different than that observed in the presence of bacteria, indicating that bacteria play an important role in mediating these effects.