Diversity and Ecology of Endohelminth Parasites in a Fish Assemblage of an Amazon River Tributary in Brazil

Purpose This study investigated the diversity and ecology of endohelminth parasites in an assemblage of 15 omnivorous and four piscivorous fish species in a tributary of the Amazon River (Brazil). Methods Fish were collected bimonthly to evaluate the diversity and ecology of endohelminth parasites in omnivorous and piscivorous fish species in a tributary of the Amazon River using traditional methods and other methods. Results A total of 4,234 parasites of 19 species (8 Nematoda, 5 Acanthocephala, 4 Digenea and 2 Cestoda) were sampled from 531 fish specimens. Procamallanus (Spirocamallanus) inopinatus and Contracaecum sp. were the predominant parasite species, and the parasites showed an aggregated dispersion pattern. Positive correlation was shown between the abundance of Contracaecum sp., Hysterothylacium patagonense and P. (S.) inopinatus, and the body size of 15.8% of the host fish examined. No difference was shown for Shannon diversity index and evenness between omnivorous and piscivorous hosts, but the richness, abundance and intensity of parasites were greater in piscivorous host fish. Conclusion In the fish assemblage, the presence of parasites in the larval and adult stages suggests that these are intermediate, paratenic and definitive hosts, reflecting the feeding habits of the omnivorous and piscivorous host species. 74.1% of the parasite species were new records for the different host species examined. The size of the hosts, trophic level and diet had an influence on the structuring of endohelminth communities and infracommunities.