Parasites in the oyster Crassostrea rhizophorae from farmed and natural stocks in the Bay of Camamu, Bahia, northeastern Brazil

Abstract

This study investigated parasites in the oyster Crassostrea rhizophorae from a farmed and a natural stock in the Bay of Camamu, Bahia, Brazil. Samples were taken in October and November, 2012 and in January, 2013. 300 oysters were fixed in Davidson’s solution and processed by means of conventional histological techniques, and were examined under an optical microscope. The following parasites were associated with C. rhizophorae: Rickettsiae-like organisms (RLOs), Sphenophrya sp. (Ciliophora), Nematopsis sp. (Apicomplexa), Perkinsus sp. (Perkinsozoa), Urastoma sp. (Turbellaria), Bucephalus sp. (Digenea), Tylocephalum sp. (Cestoda) and an unidentified copepod (Crustacea). Perkinsus sp. and Nematopsis sp. were prevalent in both environments. Nematopsis sp. had greater expression (p<0.05) in mangrove oysters than in cultivation, which was related to the more conspicuous presence of crustaceans in the first environment. Disruption of epithelial cells was caused by Rickettsiae-like organisms (RLOs) and hemocyte reaction and changes to the epithelium by Perkinsus sp. Xenomas were caused by Sphenophrya sp. in oysters from the mangrove and parasitic castration was caused by Bucephalus sp. Key words: Histopathology, mangrove oyster, oyster farming, pathogens, Perkinsus.