A National Oceanic and Atmospheric Administration study indicates that rising ocean temperatures due to climate change could increase the amount ciguatera in Gulf of Mexico and southeast Atlantic Ocean waters, however, it could have a slightly positive impact in the Caribbean.
The study notes that in the Caribbean, the toxin that causes ciguatera, Gambierdiscus, is already near the top of its preferred temperature range. Higher temperatures are likely to inhibit the growth of these cells, therefore slightly decreasing the risk of ciguatera in the Caribbean.
The study was highlighted in a recent copy of NOAA’s Fish News, the agency’s email newsletter. It appeared in the journal Ecological Modeling.
Because ciguatera-causing algae are abundant in the Caribbean, ocean warming would enable some of those species of algae to move northward to the Gulf of Mexico and southeast Atlantic, the study notes.
“They get transported northward through the Gulf Stream,” Steve Kibler, a NOAA scientist and the study’s lead author, said from his office in Beaufort, N.C.
Warmer temperatures could also mean larger and longer blooms of harmful algae, including those that produce ciguatoxins.
With the increase in the number of ciguatera-contaminated fish in the Gulf of Mexico and the southeast Atlantic Ocean, the number of cases of fish poisoning is expected to rise.
According to the study, when an increase in ciguatera is forecast, it will allow communities to target monitoring. This will save resources by focusing only on areas and times when ciguatera is likely to be present.
“Contaminated fish have no specific taste, color, or smell and there is no easy method for measuring ciguatoxins,” Kibler said. “However, we can forecast risk based on where and when we are likely to find the algae that produce ciguatoxins.”
For this study, researchers projected water temperatures in the greater Caribbean through the year 2099 based on 11 global climate models and data from NOAA buoys in the Caribbean and Gulf of Mexico. Forecasted temperature changes were then used to project the effects of ocean warming on the growth, abundance and distribution of two groups of ciguatera-causing algae, Gambierdiscus.
“This is another example of how we can use NOAA’s observing and forecasting expertise to anticipate and prepare for environmental change and its impact on coastal communities and economies,” said Mary Erickson, director of NOAA’s National Centers for Coastal Ocean Science, which conducted the research. “It contributes to NOAA’s larger efforts to build a climate-smart nation resilient to climate and weather extremes, and long-term changes.”
More than 400 fish species are known to become toxic. In U.S. waters, ciguatera occurs in Hawaii, Guam, southern Florida, Puerto Rico, the Virgin Islands, and occasionally in the Gulf of Mexico. It can also extend around the southeast U.S. coast as far north as North Carolina.
Ciguatera impedes development of fisheries resources in many regions of the world. Toxins produced by Gambierdiscus contaminate marine animals such as corals and seaweeds, and the carnivores that feed upon them, causing toxins to move into the food chain.
Kibler said that a study of the 14 different types of microscopic algae that cause ciguatera will follow this one.
People can be affected by ciguatera, the most common form of algal-induced seafood poisoning, by eating contaminated tropical marine reef fish such as grouper, snapper and barracuda. The fish can become contaminated with ciguatoxins, potent neurotoxins produced by Gambierdiscus, a microscopic algae common in the tropics.