Rotifera como bioindicador da qualidade da água no reservatório da UHE Pedra do Cavalo, Bahia

Abstract

The aim of this study was to inventory the rotifer fauna from Pedra do Cavalo HPP reservoir, assess structural characteristics of the community, and evaluate the trophic status of this reservoir. Human activity has impacted the water quality of this aquatic environment. Research on the rotifer fauna has shown that these organisms can be used as bio-indicators because of their fast response to changes in thephysical and chemical water parameters.Were performed 6 bimonthly campaigns in 6 collection points distributed 2 in Paraguaçu River (upstream and downstream of the dam) and 4 in the coastal regions of the reservoir. The samples of rotifer were obtained in the area of influence of Pedra do Cavalo HPP reservoir by filtering 100 liters of water through a graduated bucket and 64 μm plankton net. The qualitative and quantitative analyses were performed with sub-sampling and counted in Sedgwick-Rafter chamber with light microscope and stereoscopic. A total of 90 taxa were identified, belonging to 19 families from the Class Monogonont and some species from the Class Digononta (Order Bdelloidea). The Brachionidae, Lecanidae and Notommatidae and Trichorcecidae families presented the greatest richness in taxa diversity and Brachionidae was the most abundant. The most abundant species are: Keratella cochlearis, Brachionus calyciflorus, Polyarthra dolichoptera, Conochilus dossuarius, Epiphanes clavatula, Keratella lenzi, Keratella americana, Euchlanis dilatata, Lecane bulla and Euchlanis cf. meneta. The highest diversity was observed at point P5 (near the dam) and the lowest at point P4 (Jacuípe river). Monthly variation showed that the lowest diversity was recorded in October/14 and the highest in June/15. The point P4 also had the lowest average for evenness, the highest occurred in the P6 point (the dam). The values for pH were in accordance with the standard for aquatic environments. Temperature fluctuations had the expected values for the reservoir. Dissolved oxygen was below the ideal values at every point and period of this study. A longitudinal gradientwas observed from the upstream to downstream of the dam for total dissolved solids and electrical conductivity. The data for the attributes of the rotifer community in this study indicate the reservoir of Pedra do Cavalo HPP as a mesotrophic to eutrophic environment.