First study on seasonal infestation of Excorallana berbicensis (Isopoda: Corallanidae) in freshwater fishes

Abstract

The present study investigated the effects of dry and rainy season s on infestation levels of Excorallana berbicensis Boone, 1918 in Acestrorhynchus falcirostris , Ageneiosus ucayalensis , Geophagus proximus , Hemiodus unimaculatus , Psectrogaster falcata and Serrasalmus gibbus in a reservoir in the Amazon River basin, Northern Brazil. For P. falcata , the infestation levels due to E. berbicensis were greater during rainy season s . For all the species studied, the peak parasite prevalence was in the month of highest rainfall level and there were two peaks of parasite abundance: one in the month with highest rainfall level and the other in the month of transition from the rainy season to the dry season . In these hosts, around 70% of the E. berbicensis specimens were collected during the rainy season . The body conditions of the hosts also did not suffer any seasonal influence. Despite the differences in seasonal rainfall levels, there was no fluctuation in transparency, turbidity, pH, electric conductivity, temperature and dissolved oxygen levels in the water, due to the stability of these parameters during the seasonal cycle investigated in this artificial Amazon ecosystem. This was the first report on the seasonality of infestation by E. berbicensis associated with fish.