Ellen Talita Sartório Cardoso,Roseli Frederigi Benassi,S. F. Benassi,Rogerio Herlon F. Freire, Universidade Federal do ABC, , ellents_c@yahoo.com.br
Abstract
The intense and diversified uses of the reservoirs built to the power generation may cause a decreasing in the quality of the stored water. Therefore, there is an increasing necessity of managing these systems for ensuring their multiple uses. Under this point of view, this research had as the main goal to evaluate the space-temporal variability of the trophic status at an Itaipu reservoir’s compartment (Paraná, Brazil) between 1985 and 2006. The analyzed dataset was corresponding to the sites E11 and E14. The index of trophic state proposed by Carlson and modified by Toledo et al. (1983) was used to classify the reservoir in relation to its enrichment degree. The results showed that both sampled sites were classified, during the most part of the analyzed period, as oligotrophic, although the E14 had been classified as mesotrophic is some occasions. This status trophic, although may indicate alterations in water quality, it is not enough, in most of times, to put the manager system in alert. This research also showed that in recent years there was a reduction in trophic status of the Itaipu reservoir, showing the great importance of the anthropic activities and soil uses management along its hydrographic basin.
Keywords: Trophic status, space-temporal variability, Itaipu Reservoir.