Changes in parasite communities of fishes from an intermittent river in the Brazilian semi-arid, after a major interbasin water transfer

Rivers interlinking by transposition projects have multiplied in the world, altering the landscape and flow regime of continental water systems. Recently, an intermittent river in northeastern Brazil has been artificially connected to the São Francisco River basin in a water transfer project. Thus, this study aims to provide an inventory of the fish parasites from the Jaguaribe River basin in the scenarios of pre- and post-transposition, and to evaluate the short-term impacts on the parasite fauna. Of the analyzed fishes, belonging to 31 species, about 30% were parasitized. A total of 47 parasite taxa were recovered, including monogeneans (17), digeneans (9), nematodes (9), acanthocephalans (3) and crustaceans (6), and unidentified cysts of Acanthocephala, Cestoda and Digenea, representing the description of 30 new geographic records and 104 new parasite-host associations. By expanding the range of the geographic distribution of fish parasites and increasing the list of hosts, the study contributes to the knowledge of fish parasites biodiversity in the semi-arid region of Brazil and in the Caatinga domain. Considering all parasite species, significant differences were observed in total prevalence, total mean abundance, diversity index and host specificity index; the highest values of total prevalence and total mean abundance were observed in the post-transposition, while the diversity index and host specificity index was higher in the pre-transposition period. This is the first study evaluating fish parasites before and after a major water transfer event and the results will allow further evaluation of middle and long-term changes in the specific composition of fish and parasites from the receiver drainages.