Ecologia parasitária de Psalidodon fasciatus (Characidae) na bacia do rio Jaguaribe no cenário anterior à transposição do rio São Francisco

Abstract

Parasites are capable of providing diverse information about their hosts and the environment in which they live. Ichthyoparasites are widely studied around the world, however, there is a lack of data in the Northeast region of Brazil, as is the case of the Jaguaribe river basin, in Ceará. This region is undergoing an enormous anthropic impact resulting from the transposition of the São Francisco River. The fish Psalidodon fasciatus, present in Jaguaribe, serves as an important food source for carnivorous fish, being essential for the trophic balance of the ecosystem. The aim of this study was to characterize the parasite fauna of this host in the Jaguaribe river basin in the scenario prior to the transposition, identifying new geographic records of parasites and new records of host-parasite associations, in addition to verifying how the parasite indices are correlated with host characteristics. 124 fishes were collected at nine collection points along the main course of the basin in October/2019 and March/2020, the period prior to the arrival of the São Francisco River transposition waters in the basin. Necropsy was performed in search of parasites, resulting in 131 specimens from the groups: Copepoda (Acusicola sp.), Cestoda, Digenea (Magnivitellinum simplex), Monogenea (unidentified) and Nematoda (Contracaecum sp., Hysterothylacium sp., Procamallanus (S.) hilarii, Procamallanus (S.) sp. and Spiroxys sp.). All parasites found represent new geographic records and the presence of Acusicola sp. is the first record for this host. There was no influence of host sex on parasite abundance. There was a positive correlation between richness and total abundance of parasites with the total length of hosts. As for the relative condition factor (Kn) of fish, there was a positive correlation with the total abundance of parasites, the richness of parasites and the abundance of the nematode Spiroxys sp. Collector curves were produced for the parasites and hosts, with saturation of both at the sampling points of the Middle Jaguaribe. Thus, the present study constitutes an important contribution to the knowledge about the diversity of fish parasites in the Jaguaribe river basin in the pre-transposition scenario.