Efeitos da degradação ambiental sobre relações parasito-hospedeiro em riachos urbanos na cidade de Manaus/Amazonas

Abstract

Environmental degradation negatively affects a huge variety of habitats and organisms, usually resulting in the loss of biodiversity, ecological relationships and even ecosystem services. Fish have been victims of environmental degradation resulting from the loss or alteration of riparian habitats and water pollution worldwide, especially in rivers and streams in urbanized environments. However, these organisms are host to a rich parasitic fauna that may even surpass the number of host fish species, amplifying the potential effects of aquatic biodiversity loss resulting from environmental degradation. Moreover, the effects of the degradation of aquatic environments can be intensified by interactions with non-native species, present in altered environments. Given this scenario, the main objective of this study is to evaluate how environmental degradation affects endoparasitic fish communities in 26 streams located in a large urbanized area in the Brazilian Central Amazon. 827 fish belonging to 41 species, including native and non-native species, were analyzed along an environmental degradation gradient. A greater diversity of parasites was found in native fish (17 species of endoparasites, in 15 species of fish) than in non-native fish (6 species of endoparasites in 7 species of fish). Endoparasites represented four large groups: Digenea (55.3%; n = 948), Nematoda (42.7%; n = 732), Acanthocephala (1.5%; n = 26) and Pentastomida (0.3%; n = 6), totaling 21 endoparasitic morphospecies in 21 host fish species. We found that the combined effect of increased environmental degradation and decreased diversity of host fish negatively impact endoparasitic communities, causing loss of diversity and richness of parasite species. We did not observe differences in parasite abundance and richness between native and non-native fish, which may be due to the relatively recent entry of these non-native fish species in some degraded streams. However, the advance of non-native species to undisturbed environments has the potential to increase parasite dispersion and probability of disseminating new parasites to native fish, further threatening biodiversity in upland streams.