Human Health
Flower Garden Banks

close up of Ciguatera growth on algae
Toxins that cause ciguatera poisoning are produced by the dinoflagellate Gambierdiscus toxicus. This dinoflagellate can grow on algae that is consumed by fish. Credit: FGBNMS, NOAA

Why is it a concern?

There have been reports of ciguatera poisoning and high mercury levels in recent years traced to fish from Flower Garden Banks National Marine Sanctuary (FGBNMS). In February 2008, the FDA issued an advisory recommending that primary processors avoid purchasing hogfish, grouper, and snapper species captured within 10 miles of the sanctuary, and amberjack, barracuda and other pelagic species captured within 50 miles of the sanctuary.  This advisory was reissued in November 2013.

Some barracuda from FGBNMS were shown to have mercury concentrations that exceeded EPA levels for cause for concern in 1973. Testing in recent years confirms that this is still the case.

The first encounter of the toxic dinoflagellate Gambierdiscus toxicus in algae sampled at FGBNMS was in 2006. At that time it was unknown whether ciguatoxins were entering the food web of the sanctuary, and a paper in 2007 reported that the increased substrate availability provided by oil and gas platforms in the Gulf of Mexico had contributed to the increased levels of ciguatoxins regionally. Analyses following an April 2007 report of two individuals suffering from ciguatera poisoning, after consuming a gag grouper caught at the Flower Garden Banks, confirmed that the fish tested positive for ciguatoxin.

Two months later, 31 fish were collected as part of a response and provided to the Food and Drug Administration and NOAA’s National Centers for Coastal Ocean Science for analysis. Four of the fish tested positive for elevated levels of ciguatoxin — a marbled grouper (Dermatolepis inermis), scamp grouper (Mycteroperca phenax), barracuda (Sphyraena barracuda) and sand tilefish (Malacanthus plumieri).

FGBNMS continues to support NCCOS’ monitoring for the presence of the Gambierdiscus dinoflagellate by sampling, processing, and providing opportunistic algae samples.


Overview of Research

The Flower Garden Banks National Marine Sanctuary is actively seeking research partners to conduct work connected to Human Health as a sentinel issue.

Project Name PI and contacts Links

Gambierdiscus (Dinophyceae) species diversity in FGBNMS, Northern Gulf of Mexico, USA

Patricia A. Tester, NOAA-NCCOS

Ciguatera in Lionfish at the FGBNMS



Science Needs and Questions

  • What finfish species are prone to ciguatera and high mercury concentrations?
  • Over what spatial range are the fish prone to these conditions?
  • What are the frequencies of occurrence and levels of severity?
  • How do the prevalence of ciguatera and mercury concentrations compare to those found elsewhere?
  • What size range of fish is most likely to contain ciguatoxin or high mercury levels?
  • What are safe consumption levels for mercury-contaminated fish from FGBNMS?
  • Are changes in prevalence of ciguatera correlated with declining water quality, changing water temperature, or other factors?
  • Do platforms and artificial reefs play a role in proliferation of the dinoflagellate Gambierdiscus toxicus?
  • Do platforms play a role in mercury contamination?
  • Is it likely that mariculture facilities and wind farms would further the spread or persistence of G. toxicus and ciguatoxin?
  • What monitoring protocols should be in place to track the threats and under what conditions should public advisories be issued?
  • Do invasive lionfish carry ciguatoxins?

Education and Outreach Material


Invasive Lionfish

close up of Ciguatera growth on algae
Top predators on coral reefs, like barracuda, can carry ciguatera, a neurotoxin that can cause gastrointestinal and neurological symptoms in humans when ingested. Credit: FGBNMS, NOAA


Taylor, D.D. 1973. The distribution of heavy metals in reef-dwelling groupers (Serranidae) in the Gulf of Mexico and Caribbean Sea. Ph.D. Dissertation, Texas A&M University, College Station, Texas. 250 pp.

Tester, P.A., Vandersea, M.W., Buckel, C.A.; Kibler, S.R., Holland, W.C., Davenport, E.D., Clark, R.D., Edwards, K.F., Taylor, J.C., Vander Pluym, J.L.,Hickerson, E.L., Litaker, R.W. (In Press, Gambierdiscus (Dinophyceae) Species Diversity in the Flower Garden Banks National Marine Sanctuary, Northern Gulf of Mexico, USA. Harmful Algae.

U.S. Food and Drug Administration: http://www.fda.gov and search for FDA-2008-D-0079-0002.

Villareal, T.A., S. Hanson, S. Qualia, E.L.E. Jester, H.R. Granade, R.W. Dickey. 2007. Petroleum Production Platforms as sites for the expansion of ciguatera in the northwestern Gulf of Mexico. Harmful Algae 6 (2007) 253-259.