(Tesis de Doctorado, James Cook University, Australia)
Abstract: Ciguatera is a human illness caused by ingestion of toxic dinoflagellates. It is endemic to tropical regions, but has expanded globally, facilitated by increased tourism to the tropics and the distribution of frozen fish from the tropics. Fish sourced from the Great Barrier Reef (GBR) and Queensland (Qld) coastal waters are the primary source of ciguatera in Australia, however, environmental drivers of ciguatera remain poorly understood. The main causative dinoflagellate genus, Gambierdiscus, produce ciguatoxins that bioaccumulate through marine food webs. Gambierdiscus species are frequently found on macroalgal substrates and usually co-occur with other benthic dinoflagellates, such as Prorocentrum and Ostreopsis. Gambierdiscus species have been recorded in the GBR (17 ºS, 20 – 25 ºS, 27ºS) and very recently have been recorded as far south as Merimbula (37 ºS), New South Wales (NSW). Ecophysiological drivers for population range expansions are unknown, but increasing sea surface temperatures (SSTs) might facilitate range expansión south. Climate change scenarios predict an increase in frequency and intensity of warmer than average periods and environmental disturbances, which will impact coral reef health. The response of Gambierdiscus and the flow-on effect on ciguatera incidence under predicted climate change conditions are unknown for Qld. The main objective of this thesis was to contribute to the current state of knowledge on ciguatera in Qld, Australia. The focus was on the potential effect of climate, i.e. increased SSTs and environmental stressors, specifically changes in salinity, on the occurrence of ciguatera and the potential for range expansion of Gambierdiscus populations southward into colder coastal marine hábitats.