Urbanization effects on the host/parasite relationship in fishes from tributary streams of Pirapó River, Paraná State: Assessment of potential environmental bioindicators

Abstract

A parasitological study was conducted with 131 fishes belonging to the following species: Poecilia reticulata and Rhamdia quelen species. Samplings occurre d in tributaries streams of Pirapó River, located in the urban and rural area on the surrounding of Maringa city, State of Paraná. The aim of the study was to evaluate the use of fish endoparasites to determine the environmental quality of streams. There was a high similarity between parasites species considering both sets of environments. No influence of streams groups (urban and rural) on the parasites (Sebekia oxycephala and Cucullanus (Cucullanus) pinnai) prevalence and abundance was found. The Relative Condition Factor (Kn) was not different in urban and rural environments to P. reticulata species, but in R. quelen it was significantly higher in urban environments. The parasitism does not interfere in Kn, but was statistically significant in females of P. reticulata when evaluated separately by environment (urban and rural). In urban environments, the parasite S. oxycephala becomes more pathogenic resulting in lower Kn in P. reticulata females. In these, the parasite abundance resulted in negative correlation with Kn in urban streams, suggesting parasite potential damaged action in the anthropized streams. It was verified that the parasite species S. oxycephala and Cucullanus (C.) pinnai are inadequate as bioindicators of environmental quality.