First spatial distribution of potentially toxic benthic dinoflagellates in the Lesser Antilles (Guadeloupe and Martinique), Caribbean Sea

Abstract

For the first time, distribution and abundances (cells per gram of fresh macrophyte weight) of potentially toxic benthic dinoflagellates were studied around Guadeloupe (20 sites) and Martinique (six sites) islands (Lesser Antilles, Caribbean Sea). Benthic dinoflagellates were identified at the genus level and cell counts were undertaken on different host species of macroalgae and seagrasses. Abundance values of potentially toxic benthic dinoflagellates were one order of magnitude higher in Guadeloupe than in Martinique. The highest abundances of benthic dinoflagellates were found in the northern part of Guadeloupe Island, while their distribution was more homogeneous in Martinique. Ostreopsis was the dominant genus in Guadeloupe and Martinique. Regarding biotic substrate preferences, Phaeophyceae hosted the highest total abundances of benthic dinoflagellates on both islands, while the lowest total abundances were observed on Ulvophyceae in Guadeloupe and Florideophyceae in Martinique. The genus Gambierdiscus, known as the causal agent of the ciguatera fish poisoning (CFP), developed on all macrophyte groups on both islands without showing any preferences towards biotic substrates. The presence of this potentially harmful dinoflagellate genus in both islands could explain the existence of local cases of CFP in Guadeloupe and Martinique islands.