The potential role of natural tumor promoters in marine turtle fibropapillomatosis

Fibropapillomatosis (FP) in green turtles Chelonia mydas is a debilitating, neoplastic disease that has reached worldwide epizootic levels. The etiolo gy of FP is unknown but has been linked to oncogenic viruses. Toxic benthic dinoflagellates (Prorocentrum spp.) are not typically considered tumorigen ic agents, yet they have a worldwide distribution and produce a tumor promo ter, okadaic acid (OA). Prorocentrum spp. are epiphytic on macroalgae and s eagrasses that are normal components of green turtle diets. Here we show th at green turtles in the Hawaiian Islands consume Prorocentrum and that high -risk FP areas are associated with areas where P. lima and P. concavum are both highly prevalent and abundant. The presence of presumptive OA in the t issues of Hawaiian green turtles further suggests exposure and a potential role for this tumor promoter in the etiology of FP.