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Abstract

MOLECULAR ECOLOGY OF CIGUATERA CAUSING DINOFLAGELLATES IN THE CARIBBEAN

R. Wayne Litaker¹, Maria A. Faust², Mark W. Vandersea1 and Patricia A. Tester^1
1National Oceanic and Atmospheric Administration
²National Museum of Natural History
Bio

Dinoflagellate species in the genera Gambierdiscus, Coolia and Ostreopsis have a pantropical distribution between 34^oS and 35^oN and are found throughout the Caribbean including Florida, the Hawaiian Islands, French Polynesia, Australia and the Indian Ocean. The impetus for studying these species is the production of precursor toxins that are biologically modified as they accumulate in the food chain. When concentrated in fish, certain forms of these toxins cause ciguatera fish poisoning (CFP), the most common non-bacterial food poisoning known. CFP is a major health and economic problem in many tropical islands where fish is a large part of the diet and is an important constraint on the development of fisheries resources in tropical regions. Additionally, CFP poses a threat to uninformed tourists. Gambierdiscus species are thought to be the major source of toxin, but species in other genera may be similarly involved. For these reasons, discovery and identification of ciguatera-causing species is fundamental to clarifying the toxicology of CFP. Because CFP occurrences are both spatially and temporally unpredictable, we are particularly interested in determining whether CFP occurrence is related to differences in the abundance of species with varying toxicities, environmental factors which trigger toxicity, such as reef disturbance, or some combination of the two. For the past four years we have been isolating Gambierdiscus, Coolia, Ostreopsis and Prorocentrum species from habitats near the Smithsonian field station at Carrie Bow Cay and elsewhere in the Caribbean. These isolates were subjected to detailed morphological and molecular analyses which indicate the existence of four new Gambierdiscus, two Coolia and one Prorocentrum species. The molecular data are also being used to develop species-specific molecular assays and a reliable dinoflagellate DNA barcoding system. Representative morphological and molecular data supporting the new species, the DNA barcoding results, and preliminary species-specific assay data will be presented.