Diversidade de parasitas de pygocentrus nattereri (kner, 1858) (characiformes: characidae) durante o ciclo hidrológico em um lago de várzea e seu potencial como indicadora da qualidade ambiental

Abstract

Parasitism can be used as a highly sensitive monitor to detect environmental changes caused by antropic actions, however the Amazonian floodplain has natural seasonal changes caused by flood pulse. Inducing a direct response in the structure and composition of parasite species, and consequently in their life cycle. The understanding of these alterations has fundamental importance for utilizing these organisms as a tool of environmental analysis. In this study the parasitic index of P. nattereri collected in different phases of hydrologic cycle of Piranha lake was compared. The study area is located in gas pipeline Coari-Manaus construction zone, near the municipality of Manacapuru-Am. The relationship between condition factor and hepatossomatic index with parasite occurrence and the viability of use the parasitic fauna as an environmental bio-indicator were verified. The following dactylogyridean monogeneans were collected: Amphithecium microphalum, Amphitecium brachycirrum, Amphitecium calycinum, Amphithecium catalaoensis, Amphithecium junki, Pithanothecium amazonensis e Rhinoxenus piranhus, as well as the nematode Procamallanus inopinatus, the copepod Miracetyma sp. and the isopod Amphira branchialis. There is no significant correlation between the parasite occurrence with the condition factor and the hepatossomatic index of the fishes. Although there is significant variance in the parasitic index according to the different periods of hydrologic cycle, P. nattereri appears to have the conditions described in the literature to be selected as biomonitor host fish, and the monogeneans can be considered good tools in long term studies.