Abstract
Ciguatera Poisoning (CP) is the most common phycotoxin-borne form of food poisoning worldwide and is caused by the ingestion of toxic (sub)tropical fish. CP is a global issue that not only impacts human health, but has an economic impact which is estimated to be $22 million alone in the United States. CP is caused by ciguatoxin, which is produced by tropical benthic dinoflagellates belonging to the genus, Gambierdiscus, and enters the food web via herbivores and detritivores consuming macroalgae and coral rubble housing these dinoflagellates. While Gambierdiscus predominately attach itself to different species of seagrass, macroalgae, and algal turf, it remains unclear if the genus simply anchors on the host, or utilizes the macroalgae as a nutrient source. Over a 10-month study, Halimeda opuntia and other macroalgae were collected at four different sites in the Florida Keys to address this issue. The research focused on the cell densities of seven epiphytic dinoflagellates (Gambierdiscus spp., Prorocentrum lima, Prorocentrum rhathymum, Prorocentrum concavum, Prorocentrum emarginatum, Coolia spp., and Ostreopsis spp.) on H. opuntia. This research focused on the influence of various nutrients sources from the water column and the host macroalgae, H. opuntia, on epiphytic dinoflagellates cell densities on the Halimeda. The results revealed that Gambierdiscus spp. had a negative relationship with TDP in the water column. Also, the results revealed a negative relationship existed between the epiphytic dinoflagellates and C:N values in H. opuntia tissues. This novel discovery of a significant relationship between epiphytic dinoflagellates and macroalgal tissue C:N strengthens the argument for a possible biochemical link between the epiphytes and their hosts, adding complexity to the interactions between Gambierdiscus, other benthic dinoflagellates, and their host macroalgae.
