Ciguatera in the Philippines: Examining Reef Fish Vectors and Its Causative Benthic Dinoflagellates in Visayan and Sibuyan Seas

Ulysses Montojo,Naomasa Oshiro,Flordeliza Cambia,Bryan Tanyag,Karl Bryan Perelonia

doi:10.31398/tpjf/27.1.2019a0015

Abstract

Ciguatera Fish Poisoning (CFP) is primarily caused by ingesting reef fishes contaminated with ciguatoxins (CTX) produced by the Gambierdiscus species. The unpredictability of this type of food poisoning poses risks to public health and adversely affecting the fish trade industry. This study aimed to provide useful information on ciguatera in the Philippines. Different reef fish species and host-macroalgae for benthic dinoflagellates were collected in Visayan and Sibuyan Seas. Ciguatoxins were extracted from reef fish samples, and toxicity was determined qualitatively using mouse bioassay. Meanwhile, cell density estimation of toxic benthic dinoflagellates isolated from the host-macroalgae was done through microscopy. It was observed that 4.46% of the total reef fish samples were positive with ciguatoxins. Spatially, Carles, Iloilo in Visayan sea had the highest number of toxic specimens belonging to Epinephelus merra, Lethrinus lentjan, Lutjanus campechanus, Scarus quoyi, Siganus guttatus, and Sphyraena barracuda. Based on data gathered from three sampling sites, fish toxin occurrence is observed to be site-specific. Geographical conditions affect the frequency of toxic samples. Moreover, fish weight is not a good predictor of fish toxicity. For toxic benthic dinoflagellates, Gambierdiscus spp. were observed to have the lowest cell density count among other dinoflagellates averaging 7-115 cells per 100 g macroalgae. On the other hand, Ostreopsis spp. had the highest average cell density of 118-1,455 cells per 100 g macroalgae, followed by Prorocentrum spp. (207-594 cells per 100 g macroalgae). Fish toxicity is directly proportional to the occurrence of benthic dinoflagellates in areas as seen during dry season. Monitoring and management of CFP on identified reef fish vectors and its causative benthic dinoflagellates in the area are necessary to promote food safety and fair trade practice.

Highlights

Ciguatera Fish Poisoning (CFP) is a type of seafood poisoning primarily caused by the ingestion of reef fishes contaminated with neurotoxins called Ciguatoxins (CTX)
Of the total reef fishes collected, 25 fishes out of 561 samples or 4.46% tested positive with ciguatoxins
Variola albimarginata (585±49.50 g) ranked first for having the highest toxic proportion among all positive reef fishes collected. This was followed by Epinephelus merra (443.75 ± 140.81g), Lethrinus lentjan (535.00 ± 77.78 g), Siganus guttatus (508.00 ± 273.17 g), Lutjanus campechanus (480.00 ± 28.28 g), Scarus quoyi (400.00 ± 106.77 g), and Sphyraena barracuda (645.00 ± 77.78 g)

Summary

Introduction

Ciguatera Fish Poisoning (CFP) is a type of seafood poisoning primarily caused by the ingestion of reef fishes contaminated with neurotoxins called Ciguatoxins (CTX). The main organism that produces these types of toxin is a dinoflagellate belonging to the genus Gambierdiscus (Adachi and Fukuyo 1979) which colonizes on a variety of coral reef macroalgae commonly found in tropical and temperate waters (between 35°S to 35°N) of the globe (Bagnis et al 1980). In the Pacific, ciguatera has long been recognized as a widely distributed phenomenon affecting many of the island nations (Banner and Helfrich 1964). There are nearly 40,000 reported CFP cases from 17 countries and territories in the Pacific Islands, with an average annual occurrence of about one per 500 individuals from 1998 to 2008 (Skinner et al 2011).

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