Manguezal como sumidouro para ferro e alumínio: Estudo de caso para Rhizophora mangle L.
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Data
2023-03-28
Autores
Barcelos, Ully Depolo
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Universidade Federal do Espírito Santo
Resumo
Mangroves are highly productive and resilient environments. However, anthropogenic pressures associated with natural stressors cause this resilience to decrease. Trace metals are among the main anthropogenic pollutants affecting mangroves. Mangrove forests are considered to be sinks for these pollutants because of their capacity to retain them in the sediment and in the vegetal biomass. This work was developed from the ex situ cultivation of Rhizophora mangle L. seedlings cultivated in different concentrations of iron (Fe) and aluminum (Al). This thesis is composed of three chapters. The first evaluated the effect of Fe on the development, growth and physiology of Rhizophora mangle seedlings. At the end of the experiment a reduction in photosynthetic performance, reduced leaf production was observed at the highest concentration (315 μmol L -1 ). The higher the concentration of the metal in the culture medium the higher was the bioaccumulation of Fe in the plant biomass, being the roots responsible for the highest accumulation. The second chapter analyzed the morphological and physiological responses of R. mangle seedlings in different Al concentrations. Seedlings exposed to excess Al showed a reduction in photosynthetic performance and reduction of root biomass. The roots were also responsible for the higher accumulation of Al in relation to the aboveground part. This similar response for both metals suggests that the species has defense mechanisms to prevent the entry of metals especially when they are in high concentrations, such as the ultrafiltration process. The results presented show the plasticity of the species in dealing with stressors. The third chapter aimed to define sample and plot sizes in ex situ experiments using R. mangle propagules. Morphological parameters (fresh mass, length, basal middle and apical diameter) of propagules collected at the natural mouth of the Itaúnas river estuary in six different seasons were used. Initially, descriptive statistics were performed along with linear correlation measures and normality test, sample sizing and optimal plot size (top) methodologies were defined. For experiments that do not involve experimental design (i.e. sun and shade) the amount of propagules used is determined by bootstrap interval estimation where N is defined as a function of tolerated errors around the mean. The Hatheway method should be used to determine the optimum plot size for the installation of experiments in Completely Randomized Design (DIC) and Randomized Block Design (BCD). The number of seedlings per plot will be defined as a function of the number of treatments, repetitions and assumed precision. This definition of sample size and plot size is important because there is no standardization of the same in in situ and ex situ experiments with mangrove seedlings.
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Metais traço , Bioacumulação , Delineamentos experimentais , Experimento ex situ