| Resumo: |
In this study it was evaluated the aerobic and anaerobic decomposition of submerged macrophytes Egeria densa Planch. and Hydrilla verticillata (L.f.) Royle, major weeds in tropical reservoirs. It was evaluated the decay of organic matter, mineralization, humification degree of the leached, fiber content, conductivity and pH of the process and activity of cellulase enzymes, peroxidase and xylanase. Mathematical models have indicated relations between enzymatic patterns with decay of organic matter and carbon cycling. Analysis of ANCOVA and ANOVA were used to evaluate differences in the decay processes of the species. The two species showed the same heterogeneous pattern of decay of organic matter and carbon mineralization, however, different patterns of decay patterns of the fiber fraction. Incubations of both species had low values of half life for the mineralization of POC, low mineralization of DOC and high enzymatic activity, especially peroxidase, correlated to high rates of decay of fiber content, mainly lignin. The incubations of the two species exhibited different oxygen consumption, probably due to the different composition of fibers. It was conclude that these macrophytes found in tropical reservoirs may cause changes in the environment metabolism. In this context it is important to study the decomposition of invasive species and their cycles for modeling parameterization of patterns of nutrient cycling in these environments. |
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