The effects of hydrological disturbance on the intensity of infestation of Lernaea cyprinacea in an intermittent stream fish community

Abstract The effects of flood and drought on the intensity of infestation of Lemaea cyprinacea in a fish community were analysed during a hydrological cycle in an intermittent stream of the Brazilian semi-arid region. Infestation by L. cyprinacea was only observed during the wet and drying phases, and the number of parasitized fishes were higher during the drying phase, when the pool size had decreased. During the wet phase 45·5% of the parasites were attached near the base of the dorsal fin and during the drying phase 42·2% of the parasites were attached to the mid-body region. Floods disseminated L. cyprinacea in the semi-arid stream studied and drought intensified this ectoparasite infestation.