Aplicação de um Índice de Integridade Biótica para o diagnóstico e conservação das comunidades de peixes dos rios Castanho e Tupana, Amazônia Central

Abstract

The objective of this study was to evaluate the conservation status of the Castanho and Tupana rivers, adapting of the Index of Biological Integrity for the Amazon basin. From the Castanho River, 173 species of fishes were collected, and from the Tupana, 153. The orders Characiformes and Siluriformes were the dominant groups found, comprising 52.6% and 20.2% of all fish species collected from the Castanho River, and 54.2% and 22.9% for the Tupano River. Omivores were the most common trophic guild found, with 48.4% of all fishes evaluated. Carnivores took second place with 13.7%, and detritivores came in with 12.1%. Other diet classifications comprised less than 10% each. Species richness data analyzed with ANOVA showed no significant temporal or spatial differences (F= 1.23; p= 0.35), and none between collecting seasons (F= 0.78; p= 0.47). Principal Component Analysis of the rivers revealed a high correlation (Pearson) among values for temperature and turbidity with pH (r = 0.691 e r= 0.496 respectively); and conductivity with pH (r = -0.542); the Dissolved oxigen values were not higly correlated with other variables. Graphic analysis of Box Plots allowed the selection of 12 parameters of the 27 originally proposed. Spearman coefficient analysis showed high correlation (ρ > 0.70; p < 0.05) between “Richness without carnivores” – “Richness without omnivores” and “Richness without carnivores”. The Box Plots revealed that for the month of July (2010) seasonal behavior, with verification by the Kruskal-Wallis test showing small significant differences for the following variables: Family richness (K= 1.762; p= 0.414), Cichlidae richness (k= 1.935; p= 0.380), Hypoxia species richness (K= 2.440; p= 2.295), Riparian species richness (K= 1.861; p= 0.394), % Carnivores (K= 1.912; p= 0.384). Evaluation of the Biological Integrity Index values permitted the identification of the most heavily impacted collection sites for each river, as well as the overall status of the rivers in the study area. The rapid habitat evaluation procedure showed that areas near bridges for the Castanho (0.4) and Tupana (0.27) rivers are in regular to somewhat degrades states of conservation.