Mudanças espaço-temporais de variáveis limnológicas e sua influência sobre o bacterioplâncton de uma represa em área agrícola

• Autor(a) principal: Malheiros, Carolina Hortêncio
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/1209
• topic: Atividades agrícolas; Recursos hídricos; Mato Grosso; CNPQ::ENGENHARIAS::ENGENHARIA SANITARIA::RECURSOS HIDRICOS; Agricultural; Water resources; Mato Grosso

In this study we evaluated spatial and temporally limnological aspects of a dam, as well as the influence of abiotic factors on distribution and abundance of heterotrophic bacteria and Pseudomonas in one of the headwaters of the St. Lawrence River (Campo Verde / MT) which was dammed and is inserted in the agricultural area. Heterotrophic bacteria and Pseudomonas were quantified by using the techniques of pour plate and spread plate, respectively. The isolated Pseudomonas were subjected to molecular analysis in order to ascertain the diversity of these bacteria in the reservoir. The biotic (heterotrophic bacteria, Pseudomonas and chlorophyll-a) and abiotic factors (precipitation, temperature, water and air, electrical conductivity, dissolved oxygen, pH, turbidity, total phosphorus, nitrite, nitrate and ammonium) were evaluated by Spearman correlation (r), cluster analysis and principal component analysis of the dam three sampled points, and the water column, every two months during the year 2010, order to verify the correlation between the biotic and abiotic variables and which of them most of the variations between different data sampling points, depth of the dam and observation periods. From the data of chlorophyll-a and total phosphorus it was possible to determine the trophic state index (IET) of the dam. The results indicated that the following variables - total phosphorus, pH, and DO disagreed with the recommendations established by CONAMA 357/05 considering the rivers classification system for Class II. The IET used allowed to evaluate the trophic state of the dam, since it is eutrophic. Statistical analysis indicated strong correlation between variables such as precipitation, heterotrophic bacteria, water temperature, electrical conductivity, apparent color, turbidity, and total phosphorus indicating the influence of seasonality in agricultural areas. We isolated 112 strains of Pseudomonas of which 60 were subjected to phylogenetic analysis of BOX-PCR. Molecular analysis showed similarity ≥ 70% in most isolates among the sites, indicating a possible predominance of one species of Pseudomonas, since the 60 isolates subjected to molecular analysis, 44 had similarity. Of these 44 isolates comprising 28 samples of sediment-water interface. The seasonal factor didn’t interfere with similar groups of Pseudomonas, and 21 of the isolates belong to the dry season and 23 during the wet season. However, there is between 16 to 13 are dissimilar isolated from three of the rainy season and dry season, indicating that the seasonality may affect the diversity of some species of Pseudomonas. Molecular analysis proved to be an important tool in characterizing the diversity of Pseudomonas, and ecological aspects of seasonal and anthropogenic influences. It was observed that the variations among the sampling points are more significant than in the water column for most variables, probably due to particular characteristics of each sample point and because it is a dam with little depth.