Ecological status evaluation of Carlos Botelho (Lobo/Broa) reservoir, São Paulo, using Evenness Index to phytoplankton community

Aline Martins Vicentin, Eduardo Henrique Costa Rodrigues, Marcelo Luiz Martins Pompêo


Aim: The present study aims to evaluate the ecological status of the Broa reservoir through the application of the ecological index Evenness E2. Methods: The collection was performed during the dry period (jun/2015) in 9 sample points distributed along the longitudinal profile, in superficial water collections and fixation with acetic lugol (1%). The qualitative analysis was performed trough the identification of organisms using binocular optical microscope under lamina and coverslip with micrometer eyepiece and recent bibliography. The quantitative analysis was performed using the sedimentation chamber method and inverted microscope analysis. From the density and richness data, the Uniformity Index was calculated in the PAST program (3.13). The guide values used in this study were set according to the literature covering 5 classifications (High, Good, Moderate, Low and Bad) of the Evenness E2 index for phytoplankton, being 1 the maximum value. Results: The values observed ranged from 0.1142 in P1 to 0.1468 in P3, being classified as "Bad", since values were below 0.21. Conclusions: The result is associated to the sanitary problem of the reservoir, due to the occurrence of consecutive blooms, indicating a great contribution and amount of nutrients in the region. A massive occurrence of cyanobacteria was observed, with emphasis on the species Aphanizomenon gracile, which may be related to the adaptive advantages that this class presents on the community in eutrophic environments. Other activities occur in the basin that can contribute effectively to the eutrophication process of the reservoir, such as the discharge of domestic and agricultural effluents. Therefore, it needs attention to the reservoir, since water quality is compromised due to the presence of potentially toxic species, which may harmed the multiple uses of the reservoir, as well as human and ecosystem health.


Phytoplankton; Ecological Uniformity Index; Evenness Index E2; Water quality; Eutrophication

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Departamento de Ecologia – IB - UNESP/Rio Claro. Avenida 24 A n° 1515. CEP 13506-900. Rio Claro (SP) / Brasil