Ação de um fungicida cúprico no crescimento de uma macrófita aquática flutuante

Abstract

Due to their high productivity and contribution to nutrients and carbon cycling, the functional performance by aquatic macrophytes communities has been widely discussed, since these organisms can directly influence the metabolism of limnic ecosystems, as lakes and reservoirs. This study determined the primary aquatic production (i.e., the growth of a floating aquatic macrophyte) to diagnose how substances from human activities (i.e., emerging contaminants) can cause aquatic environment contamination and affect aquatic macrophytes primary aquatic production. Thus, this study followed the interference caused in Ricciocarpus natans growth (floating species) when exposed to two different concentrations (2.5 e 5.0%) of a fungicide called Bordeaux mixture. When in contact with different fungicide concentrations, R. natans presented a significant negative impact on their growth in comparison with the individuals in the control treatment; besides not being able to reproduce. The application of the logistic model was only possible in the data obtained from the growth of R. natans in the control bioassays, as there was an accumulated growth in length in these treatments. The values obtained for μ (growth coefficient) were 0.027 ± 0.004 (control of the test conducted with 2.5% Bordeaux mixture) and 0.035 ± 0.003 day-1 (control of the test performed with 5.0% Bordeaux mixture). The individuals in the Bordeaux mixture bioassays showed chlorosis losing their ability to carry out photosynthesis. The mathematical modeling presented the individuals accumulated growth in concentrations declined, showing, a negative impact caused by Bordeaux mixture on the macrophyte. Based on the results found, the contact between this fungicide and the aquatic macrophyte presented a negative impact both in primary production and in reproduction.