Abstract
Benthic dinoflagellates are known as causative organisms of ciguatera. Despite the ciguatera poisonings that have been reported in southern islands of Japan, few studies have been carried out on the distributions of these organisms.
In this study, distributions of benthic dinoflagellates including ciguatera causative organisms were examined in Akajima Island, Kerama Islands, Okinawa, Japan.
Prorocentrum species occupied a high percentage of density compared with others, especially P. lima was most abundant and its maximum density was 236 cells/g (wet weight) of alga on Sargas-sum sp.. Densities of P. emarginatum and P. concavum were also high next to P. lima. Gambierdiscus toxicus known as a main producer of ciguatoxin and maitotoxin was rather low in the mean density (6.7 cells/g of alga), but its maximum cell density (51.0 cells/g of alga) was a thousand times higher than that examined at Okinawa Island and Inshigaki Island.
