First Report of sp. Parasites Infecting Dinoflagellates from Brazilian Coastal Waters Amoebophrya

Members of the parasitic dinoflagellate genus lethally infect other marine dinoflagellates, including red tide forming and toxin-producing species. The known geographical distribution of sp. parasites in costal waters of the northern hemisphere is more likely reflecting a lack of information from other areas rather than the actual picture. We investigated the presence of sp. parasites infecting dinoflagellate cells from South Atlantic coastal waters. Samples were taken in early summer in the Cabo Frio area, Southeast Brazil, using a 20 m mesh-size plankton net. Infection of potential dinoflagellate hosts was analyzed by epifluorescence microscopy after SYTOX staining. Two unidentified sp. were found to be infected by sp. at prevalence levels of 0.5 and 2%. Several other dinoflagellate species were present in the samples, though without detectable infection, indicating some degree of host-specificity by the parasites. The detection of infection in dinoflagellates obtained at a single sampling occasion suggests that parasitism by sp. might be a common phenomenon in the area. Amoebophrya