Pathogens in two commercially-important bivalve species from the Pacoti River estuary, Ceará State, Brazil

Abstract

In Ceará State’s estuaries, the mangrove oyster,  Crassostrea rhizophorae and the cockle  Anomalocardia brasiliana are  harvested by local communities, representing a very important socioeconomic activity. Whereas the pathogens can cause mortality in  mollusk populations, this study aimed to investigate the occurrence of parasites in  C. rhizophorae and in  A. brasiliana from Pacoti River  estuary, Ceará State. During the period from February, 2008 to January, 2009, samples of cockles and oysters (n = 360 per species) were  collected monthly for histopathological analyses. The results in cockles showed bacterial colonies rickettsia-type (7.2%), metazoan possibly  bucephalids (35.8%),  Tylocephalum (31.7%) and metacercariae of trematodes (0.5%). In oysters, it was observed protozoa of the genera  Nematopsis (83%), unidentified protozoans (3.9%),  Ancistrocoma (7.2%) and the metazoa : Urastoma  (0.8%), bucephalids (0.2%)  and  Tylocephalum (3%). Despite the high prevalence of  Nematopsis  in oysters, damage was not observed in the tissues of infected  animals. In contrast, the infestation by bucephalids in the gonads caused the castration of the host. The results indicate that those mollusk  species must be monitored in their habitat so as to keep pace with the evolution of the prevalence and the appearance of new pathogens.