Community Impacts of South Pacific Algal Toxin Exposure at Multiple Scales

Ciguatera fish poisoning (CFP) is a non-bacterial form of human foodborne illness. It is caused by the consumption of seafood contaminated by ciguatoxins (CTXs), which are produced by benthic dinoflagellates, such as Gambierdiscus spp. and Fukuyoa spp. It affects annually 50,000 – 500,000 people in the world, probably due to increasing international trade in coral reef food fish. CFP is particularly prevalent in the developing Pacific Island Countries and Territories (PICTS). Statistical analysis of the temporal changes in mean annual CFP incidence in the PICTS showed a 60% increase from the 1973–1983 to the 1998–2008 periods, although inter-year variability is high. There was, however, no statistically significant correlation between mean annual CFP incidence and occurrence of coral bleaching, cyclone incidence or perceived coral reef condition. It is possible that the elevated CFP cases reported in the PICTS could at least partly be a consequence of the enhanced public awareness and improved CFP reporting mechanism. The reported acute clinical syndromes of CFP include a range of neurologic, gastrointestinal and cardiac disorders which can last for weeks to months. Furthermore, chronic exposure of the most potent CTX, Pacific CTX-1 (P-CTX-1, also known as CTX1B), was recently found to adversely affect spatial memory and decision making in rats. Fish has traditionally been a primary source of dietary proteins in the PICTS. People in the PICTS may avoid eating fish to minimize the risk associated with CFP, leading to secondary medical problems such as diabetes as a consequence.

Coral ecosystems are known for their high ecological and conservation values. Their ecotourism values and annual retail values associated with reef food fish trade are also significant. Our recent findings indicate that CTXs can negatively impact the physiology, behavior, and survival of fish, crustacean and marine mammals, and thus CTXs may have an influence on the structure and function of coral ecosystems in the PICTS. Following outbreaks of CFP, tons of reef fishes were prohibited for sale in the marketplace each year, and this may cause significant economic loss to endemic PICTS that rely heavily on coral reef fisheries. As well, the treatment of CFP is expensive. Significant medical expenses due to CFP outbreak may impose further social and economic burden to the PICTS. To develop an effective management strategy to minimize risks associated with CTXs and CFP, it is crucial to enhance our understanding on occurrence of CTX-producing benthic dinoflagellates, spatiotemporal distribution of ciguatoxic fish, and food web transfer, toxicokinetics and toxicodynamics of CTXs in the affected ecosystems.