A simple model capable of simulating the population dynamics of Gambierdiscus, the benthic dinoflagellate responsible for ciguatera fish poisoning

Ciguatera fish poisoning (CFP) is the most prevalent form of phycotoxin-borne seafood poisoning in the world. It afflicts tens of thousands of individuals annually resulting in economic impacts on the order of tens of millions of dollars per year in the United States alone. One of the biggest hurdles hindering management strategies to monitor for and limit exposure to CFP is the sporadic nature of CFP outbreaks, both spatially and temporally. The purpose of this effort was to develop a simple, one-dimensional model that used essential physico-chemical parameters to adequately simulate the population dynamics of the causative organism behind CFP events, the benthic dinoflagellate, Gambierdiscus spp. The design data for this model came from seasonally comprehensive information for Gambierdiscus cell density and associated nutrient and physico-chemical data that were collected monthly over 3.5 years at two windward and two leeward sites on the island of Hawaii. Data from the windward sites were used to construct and calibrate the model, which was then verified against actual Gambierdiscus cell density values that were collected at the leeward sites. Additional modeling scenarios indicated that bloom scenarios resulted from subtle (yet complementary) changes in environmental conditions, and that nutrient enrichment and warming sea surface temperatures stimulated Gambierdiscus growth and resulted in higher cell densities. The results from this proof-of-concept effort to simulate the population densities of this benthic dinoflagellate suggest promise for more elaborate modeling efforts, and their potential value to protect against human impacts from future CFP outbreaks.