Um rio de unidade de conservação, como ambiente pristine para ictiofauna neotropical

Abstract

Lotic environments are influenced by outer regions, but also influence adjacent terrestrial environments. Studies carried in conservation areas are still scarce, especially when they refer to aquatic ecosystems, which are only preserved if inserted to a Conservation Unit. Another factor that hinders the preservation of lotic environments is the study techniques used, which are still based on terrestrial and marine environments. The objective of the present study was to analyze limnological parameters of a preserved river, the Floriano River, evaluating the quality of its waters through the comparison between two sampling points. The study was conducted between February and December 2010 in two parts of the river called stretch 1 and stretch 2, where bimonthly the following variables were sampled: air and water temperature, dissolved oxygen and oxygen saturation, pH, conductivity, turbidity and transparency. Seasonal differences were observed during the evaluation period of the study. The average air temperatures fluctuated from 15.6° C to 27.0° C, while the average water temperatures were between 17.9° C to 26.6° C. The minimum and maximum values observed for oxygen saturation were 83.6% and 111.3%, consistent with the standards of a preserved river. Transparency average values stayed between 0.3 and 0.9 m, showing a good water quality. Dissolved oxygen, pH and turbidity presented values within the standards established by the CONAMA Resolution 357/05. Considering the rivers belonging to the Iguaçu National Park, the Floriano River is the most preserved one, since its basin is fully inserted in this Conservation Unit, presenting no changes in its natural habitat. Thus, this area represents a good site for studies of abiotic variables and for setting standards to be used in the evaluation of anthropogenic environments