Ciguatera Fish Poisoning
Background
Ciguatera Fish Poisoning (CFP) is a type of seafood poisoning that affects people when they eat reef-dwelling top-level predatory fish such as barracuda, grouper and snapper. Unfortunately there is no simple screening method to identify a fish with high levels of CFP and cooking the fish does not break down the toxin.
The symptoms of CFP can include a wide range of gastrointestinal issues such as cramps, nausea, diarrhea and vomiting during the initial phase of the illness. Many people subsequently develop neurological problems where they may experience headaches, numbness, reversal of hot and cold sensations, muscle aches, or strange tastes/feeling in the mouth. Symptoms can last for years in some cases and additional poisonings tend to increase symptom severity. While death is rare, it is possible.
CFP is caused by gambiertoxins produced by single-cell benthic dinoflagellates in the genus Gambierdiscus that live and grow on the macroalgae which now dominates many reefscapes. Many reef organisms, primarily smaller fish and invertebrates, consume Gambierdiscus directly or indirectly as they graze on macroalgae or turf algae, respectively. These organisms convert ingested gambiertoxins to harmful ciguatoxic compounds via metabolism, and store these compounds in their fat tissues without adversely affecting their health. Subsequently, larger fish biomagnify (accumulate and concentrate) these compounds in their tissues when preying on the aforementioned smaller organisms. Ultimately these larger, seemingly healthy fish are consumed by humans who are sickened by the ciguatoxins.
Dr. Smith's lab participates in the regional study of Ciguatera in the greater Caribbean known as CiguaHAB. CiguaHab is "an international team of experts from universities and laboratories around the Greater Caribbean Region which has been assembled to investigate the conditions that lead to Ciguatera Fish Poisoning outbreaks and create a model which will lead towards better predictive capability and assist in elucidating the effects of global warming and other climatic or environmental perturbations on this important public health phenomenon." For a detailed description of the entire CiguaHAB project click here.
Completed in 2013, the CaribCATCH project looked at the relationship between climate, people, and the ecology of ciguatera on coral reefs.
Ciguatera at UVI
Dr. Smith's part in the larger initiative to understand, prevent, and control CFP is to coordinate field sampling and data output for the four primary field sites in St. Thomas. There are two nearshore and two offshore sites located on the south side of St. Thomas (where most of the fish which induce poisoning are caught). Every month each site is sampled for coral health, benthic community composition, sedimentation rates, Gambierdiscus toxicity and abundance, and water quality parameters such as temperature, salinity, dissolved oxygen, chlorophyll, turbidity, and nutrient levels. Also, every three months adult reef fish are collected for tissue ciguatoxicity analysis. This data is shared among the many participating organizations in a unified attempt to address this very real problem of CFP.
Relevant References
Loeffler C, Richlen M, Smith TB (in press) In situ effects of grazing, nutrients, and depth on the ciguatera-causing dinoflagellate Gambierdiscus in the U.S. Virgin Islands. Marine Ecology Progress Series
Radke EG, Grattan LM, Cook RL, Smith TB, Anderson DM, Morris Jr. JG (2013) Ciguatera incidence in the US Virgin Islands has not increased over a 30-year time period despite rising seawater temperatures. American Journal of Tropical Medicine and Hygiene 88:908-913
Robertson A, Garcia AC, Flores Quintana HA, Smith TB, Castillo BF, Reale-Munroe K, Gulli JA, Olsen DA, Jester ELE, Hooe-Rollman JI, Jester ELE, Klimek BJ, Plakas SM (2013) Invasive Lionfish (Pterois volitans): A potential human health threat for Ciguatera Fish Poisoning in tropical waters. Marine Drugs 12:88-97
