This study confirms the presence of the toxigenic benthic dinoflagellates Gambierdiscus belizeanus and Ostreopsis spp. in the central Red Sea. To our knowledge, this is also the first report of these taxa in coastal waters of Saudi Arabia, indicating the potential occurrence of ciguatera fish poisoning (CFP) in that region. During field investigations carried out in 2012 and 2013, a total of 100 Turbinaria and Halimeda macroalgae samples were collected from coral reefs off the Saudi Arabian coast and examined for the presence of Gambierdiscus and Ostreopsis, two toxigenic dinoflagellate genera commonly observed in coral reef communities around the world. Both Gambierdiscus and Ostreopsis spp. were observed at low densities (<200 cells g⁻¹ wet weight algae). Cell densities of Ostreopsis spp. were significantly higher than Gambierdiscus spp. at most of the sampling sites, and abundances of both genera were negatively correlated with seawater salinity. To assess the potential for ciguatoxicity in this region, several Gambierdiscus isolates were established in culture and examined for species identity and toxicity. All isolates were morphologically and molecularly identified as Gambierdiscus belizeanus. Toxicity analysis of two isolates using the mouse neuroblastoma cell-based assay for ciguatoxins (CTX) confirmed G. belizeanus as a CTX producer, with a maximum toxin content of 6.50 ± 1.14 × 10⁻⁵ pg P-CTX-1 eq. cell⁻¹. Compared to Gambierdiscus isolates from other locations, these were low toxicity strains. The low Gambierdiscus densities observed along with their comparatively low toxin contents may explain why CFP is unidentified and unreported in this region. Nevertheless, the presence of these potentially toxigenic dinoflagellate species at multiple sites in the central Red Sea warrants future study on their possible effects on marine food webs and human health in this region.

这项研究证实了产原性底栖鞭毛鞭毛虫Gambierdiscus belizeanus和Ostreopsis spp的存在。在红海中部。据我们所知，这也是沙特阿拉伯沿海水域中这些类群的首次报道，表明该地区可能发生雪茄鱼中毒（CFP）。在2012年和2013年进行的实地调查中，从沙特阿拉伯沿海的珊瑚礁中收集了总共100个Turbinaria和Halimeda大型藻类样本，并检查了Gambierdiscus和Ostreopsis的存在，这两个产于藻类的产鞭毛藻属通常在附近的珊瑚礁群落中观察到。世界。两个都Gambierdiscus和Ostreopsis spp。在低密度（<200个细胞g ^-1湿重藻类）下观察到。Ostreopsis spp。的细胞密度。明显高于Gambierdiscus spp。在大多数采样点，两个属的丰度与海水盐度呈负相关。为了评估该地区雪茄毒性的潜力，在培养物中建立了几种冈比亚菌的分离株，并检查了其物种身份和毒性。所有分离物在形态和分子上均被鉴定为Gambierdiscus belizeanus。使用基于小鼠神经母细胞瘤细胞的雪茄毒素（CTX）分析对两种分离物的毒性进行了分析G. belizeanus作为CTX生产者，最大毒素含量为6.50±1.14×10 ^-5  pg P-CTX-1当量。单元格^-1。与来自其他地方的甘比氏菌分离株相比，它们是低毒菌株。低Gambierdiscus密度与它们相对低的毒素含量观察沿着或许可以解释为什么CFP不明和未报告的在这个区域。尽管如此，在中部红海的多个地点存在这些潜在的产毒力鞭毛藻物种，值得对它们对该地区海洋食物网和人类健康的可能影响进行进一步研究。