Histopatologia de brânquia e fato de condição de Astyanax aff. paranae (PISCES) como indicadores de contaminação aquática no centro-noroeste do Paraná

Abstract

This study aimed to evaluate the gills’ histopathology and nutritional status of Astyanax aff. paranae (Teleostei, Characidae) by calculating the index Bernet and allometric condition factor, respectively. For this, two collections were made (summer/ winter 2011), in three sampling sites with different levels of anthropic interference, two of these points are located at the Rio Campo (downstream and upstream of Campo Mourão city - PR) and there is a control point in Concordia stream in the Biological Reserve of Perobas in Tuneiras do Oeste city - PR. The morphometric data of fishes were measured (length and weight) and analyzed. The length-weight relationship of the specimens collected in winter was negatively allometric (b = 2.95), and for the ones collected in the summer it was positively allometric (b = 3.44). From the two-way ANOVA it is possible to find significant interaction between the factors season and sample point. From the Tukey test, it could be seen that the highest values of K occurred in the summer. In this season it also was possible to detect significant difference between the sampling points, being the highest value obtained at the point downstream. High values of b and K in summer, especially at the point downstream, suggests an answer to the specimens with a higher input of nutrients. After the histological procedure, the main histopathology damages found were: lamellar fusion, epithelial detachment, aneurysm, lamellar hypertrophy and hyperplasia, being the last one of the most common alterations in both seasons. It was found by two-way ANOVA test variables that station and sampling point showed significant differences between them, so their joint analysis would be necessary, since the Tukey test revealed that the downstream point in the summer had a higher rate histopathology while Rebio the had the lowest in winter. Comparing the two seasons, it could be found that for Rebio and downstream the histopathology increased in the summer while the upstream point remained intermediate. The results indicate that the specimens from the Rio Campo are subject to a bigger environmental stress, mostly the ones from the downstream due to urban effluents.