Variação espacial da parasitofauna de Leporinus friderici (Anostomidae, Osteichthyes) em uma planície de inundação subtropical.

Abstract

The Upper Paraná River floodplain has high aquatic diversity, but has been experiencing increasing anthropogenic pressures resulting mainly from hydrological regulation by dams, with direct impacts on biodiversity and ecological interactions. In this context, this study aimed to characterize the parasitic fauna associated with Leporinus friderici and compare the taxonomic composition, abundance, and richness of ectoparasites between the Baía and Ivinhema subsystems. The hypothesis was that the Baía subsystem would present higher values of abundance and parasitic richness, due to its semi-lentic characteristics, which potentially favor the maintenance of more complex parasitic life cycles. The collections were carried out between September 2024 and June 2025 in the floodplain of the Upper Paraná River, with 64 specimens of L. friderici being analyzed, subjected to biometric registration and parasitological investigation of the gills and nasal cavities, with morphological identification of the parasites. Parasitological descriptors were calculated and differences in community composition between subsystems were evaluated using Permutational Multivariate Analysis of Variance (PERMANOVA) and Multivariate Dispersion Analysis (PERMDISP), in addition to visualizing community structure using Principal Coordinate Analysis (PCoA). In total, 19 ectoparasite taxa were identified. The gills were the main site of infestation, with 601 monopisthocotyleas parasites recorded, while the nasal cavities had a lower parasitic occurrence and no parasites were observed in the eyes. The results revealed structural differences between the subsystems of the Upper Paraná River floodplain, with greater abundance and richness in the Baía subsystem, related to local hydrodynamic conditions and environmental bioindicator potential.