Interdisciplinary Seminar: Stephanie Smith

The UNC-CH Department of Marine Sciences presents the interdisciplinary seminar of graduate student, Stephanie Smith. This event will be held on Monday, March 30th, at 12:30 pm. This event will be held ONLINE ONLY and it will be available online via Zoom (Meeting ID: 291 853 980).

Title: Ciguatera range expansion in the face of climate change

Abstract: Ciguatera toxins are heat-stable compounds produced by the dinoflagellate Gambierdiscus and tend to concentrate in fish organs. When these fish are consumed by humans, the toxin causes ciguatera food poisoning that is endemic to the Caribbean, Northeast Australia, and mid-Pacific Islands. Until recently, ciguatoxin-producing dinoflagellates have been restricted to more tropical latitudes between 35N and 35S; however, the range of ciguatera is predicted to expand rapidly in the face of global climate change. One study examined the relationship between Gambierdiscus growth rate, rising sea-surface temperatures (SST), and ciguatera incidence rates in the Caribbean. In culture experiments, it was shown that Gambierdiscus spp. have the highest growth rates at temperatures > 29°C, suggesting warmer temperatures may enhance exposure to ciguatera toxin. Indeed, when average SST was plotted with ciguatera incidence rates in the Caribbean, this study observed that all ciguatera cases occurred where the average SST temperature was > 25°C and the highest incidence rates were in the Eastern Caribbean where water temperatures are warmest and least variable. Using data collected from NOAA buoys throughout the Gulf of Mexico and Caribbean Sea, researchers found that over the past 30 years the average number of days where SST was >29°C has nearly doubled from 44 to 86 days per year. Caribbean SST is predicted to increase by 2.5-3.5°C over the next century, and modeled ciguatera incidence rates under these conditions suggest that ciguatera will increase by 200-400% in the United States during this time period. To mitigate the effects of global climate change on ciguatera range expansion, future studies should address methods for rapid ciguatoxin detection in the field and more strict fishing regulations to reduce human exposure to contaminated fish.