Ciguatoxin – The risky business behind Roi consumption

Ciguatera fish poisoning (CFP) is a food borne illness that occurs in the tropics, between the latitudes of 35°N and 35 °S (Lehane and Lewis, 2000). Ciguatoxin (CTX) is a naturally occurring marine toxin that is generated by photosynthetic dinoflagellates from the genus Gambierdiscus spp. These lipid-soluble compounds are heat stable, tasteless and odorless. Through biomagnification of the marine reef ecosystem, CTX is accumulated in herbivorous and carnivorous reef fish, eventually resulting in consumption by humans. The ingestion of CTX can lead to a number of gastrointestinal, neurological, and/or cardiovascular complications that have the potential to linger for a number of weeks (Cameron et al., 1991; Beinfang et al., 2012; Benoit et al., 2000; Arena et al., 2004; Friedman et al., 2008).
CFP is recognized as the most common food borne disease in association with marine finfish consumption (De Fouw et al., 1999; Lehane, 2000; Dickey and Plakas, 2010). Recent estimates of ciguatera pervasiveness in effected regions range from less than 0.1% of populations of continental land masses( e.g. Florida, USA) to more than 50% of populations of the small islands that make up the Caribbean and South Pacific (see reviews by Lews, 1986a; Lange, 1994; Fleming et al., 1998, 2001). The geographical prevalence of CFP is expected to spread latitudinally due to the rapid expansion of international trade in seafood from pantropic fisheries (De Fouw et al., 1999; Lehane, 2000).
Cephalopholis argus, frequently referred to as roi, blue-spotted grouper, or peacock grouper, are dominant, demersal predators that inhabit the Indo-Pacific ecosystem. In hopes of strengthening local fisheries, C. argus was introduced to Hawaii in the 1950′s (Randall, 1987). Although the population of the newly introduced species remained relatively low for a few decades, by the 1980′s, roi biomass exceeded all other reef fish predators (Dierking, 2007). C. argus became closely associated with ciguatera fish poisoning throughout Hawaii. As a result, local spear fisherman have diminished their targeting of this species, thus removed a form a biomass control (Dierking and Campora, 2009).
Seafood consumption and subsistence practices are highly valued throughout a number of Asian American and Pacific Islander cultures. Within these populations, ingesting organs other than the muscle is very common. Thus, these cultures are at a higher risk for toxic contamination from seafood (Sechena, 2003). The objectives of this study were to determine the relative concentrations of ciguatoxin found in the edible parts of C. argus. The edible parts are defined as the muscle, brain, liver and gonads (i.e. total mass excluding visceral mass and skeletal mass). By determining the concentration of CTX in the edible organs, conclusions can be made about the relative health risks of eating various parts of the fish.
As a top carnivore in the marine reef food web, C. argus is a prime vector of CFP (Lehane and Lewis, 2000); hence its focus for this investigation. The ingestion of ciguatoxin proposes a potential risk for recreational and subsistence fishermen deriving nutrition from coral reef environments. Ciguatoxin is a lipophilic compound that is sequestered in fatty acid rich organs such as the brain, liver and gonads. These same organs are often consumed to various degrees by cultures that rely on coral reef environments for their essential nutrition. There has been one previous study in regards to the anatomical distribution of ciguatoxin in marine finfish (refer to Venoux, 1985). This experiment used different techniques to determine the concentration of CTX in various body parts for a number of different organisms. Similar conclusions were made in relation to the toxicity of organs in marine finfish.
The ciguatoxin concentration of the muscle alone was much less than that found in the various organs. However, the ingestion of toxins from the organs alone do not compare to the ingestion of the muscle tissue. The percentage of CTX content in the muscle was in so much excess that it is unlikely that the consumption of the organs in conjunction with the muscle tissue will increase the risk of CFP. It is clear that the majority of the risk of CTX involves the intake of the muscle tissue, as seen by data with this finfish species.

Undergraduate research done by Carly Goodman

REFERENCES

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