Diversidade micológica em rios com características hidrogeoquímicas distintas: as leveduras como potenciais bioindicadores
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2009
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Os fungos são potenciais bioindicadores de qualidade da água pois manifestam elevada flexibilidade ecológica, apresentando tolerância a variações na mineralização, temperatura, pH e poluição. Foram recolhidas amostras de água de 6 locais pertencentes a 4 rios (Corgo, Pinhão, Tua e Olo) da bacia hidrográfica do Rio Douro, tendo sido, posteriormente, realizada a análise dos seus parâmetros hidroquímicos e microbiológicos. Os rios Corgo, Pinhão e Tua, são fortemente influenciados por actividades antropogénicas, ao contrário do rio Olo onde se verifica baixo impacto humano. O estudo foi realizado durante 2,5 anos, no inverno e no verão. As amostras de água dos diferentes locais apresentaram valores baixos de Condutividade Eléctrica (CE), entre 6,0 μS/cm (Olo) e 116 μS/cm (Zimão) e valores de pH geralmente àcidos, à excepção do rio Tua (pH entre 5,0 e 7,8). A análise de componentes principais (PCA) revelou diferenças significativas entre os locais em estudo, relativamente às épocas do ano e semelhanças a nível físico-químico entre os rios Corgo e Tua, que apresentam maior índice de perturbações no meio. De uma forma geral, o número de fungos mostrou-se inferior no inverno e superior no verão, atingindo os valores mais elevados nas amostras de Zimão e Flores (>5000 UFC/L) e mais baixos nas amostras do Olo. A análise ANOVA-Factorial mostrou que as variações nas quantidades de fungos filamentosos estão relacionadas com a mudança de estação e com as características dos locais e a variação nas contagens de leveduras está essencialmente relacionada com as características dos locais. O estudo molecular dos isolados de leveduras revelou a existência de 70% de morfotipos diferentes, sendo verificada menor diversidade no rio Tua. Os fungos e particularmente as leveduras, parecem responder às alterações nos ecossistemas aquáticos quando estes sofrem a influência de pressões, quer naturais, quer antropogénicas.
The fungi are potential bioindicators of water quality as they manifest high ecological flexibility, showing tolerance to variations in mineralization, temperature, pH and pollution. There were collected water samples from 6 sites belonging to 4 rivers (Corgo, Pinhão, Tua and Olo) basin of the Douro River, and was subsequently carried out the analysis of their hydrochemical and microbiological parameters. Corgo, Pinhão and Tua rivers are strongly influenced by anthropogenic activities, unlike the Olo river where there is low human impact. The study was conducted for 2.5 years in winter and sum-mer. Water samples from the different sites showed low Electrical Conductivity (EC) between 6.0 μS/cm (Olo) and 116 μS/cm (Zimão) and pH values generally acid, except at Tua river (pH between 5.0 and 7.8). The principal component analysis (PCA) revealed significant differences between the study sites in relation to seasons and also showed physico-chemical similarities between Corgo and Tua rivers, which have a higher rate of environment disturbances. In general, the number of fungi demonstrated to be lower in winter and higher in summer, reaching the highest values in samples of Zimão and Flores (>5000 CFU/l) and lowest in the samples of Olo. The ANOVA-factorial analysis showed that variations in the amounts of filamentous fungi are related to seasonal changes and the local characteristics and variations in counts of yeasts are mainly related to the characteristics of sites. The molecular analysis of yeast isolates revealed 70% of different morphotypes, and there was found less diversity in the river Tua. Molds and yeasts in particular, seem to respond to changes in aquatic ecosystems since they are influenced by pressures, either natural or anthropogenic.
The fungi are potential bioindicators of water quality as they manifest high ecological flexibility, showing tolerance to variations in mineralization, temperature, pH and pollution. There were collected water samples from 6 sites belonging to 4 rivers (Corgo, Pinhão, Tua and Olo) basin of the Douro River, and was subsequently carried out the analysis of their hydrochemical and microbiological parameters. Corgo, Pinhão and Tua rivers are strongly influenced by anthropogenic activities, unlike the Olo river where there is low human impact. The study was conducted for 2.5 years in winter and sum-mer. Water samples from the different sites showed low Electrical Conductivity (EC) between 6.0 μS/cm (Olo) and 116 μS/cm (Zimão) and pH values generally acid, except at Tua river (pH between 5.0 and 7.8). The principal component analysis (PCA) revealed significant differences between the study sites in relation to seasons and also showed physico-chemical similarities between Corgo and Tua rivers, which have a higher rate of environment disturbances. In general, the number of fungi demonstrated to be lower in winter and higher in summer, reaching the highest values in samples of Zimão and Flores (>5000 CFU/l) and lowest in the samples of Olo. The ANOVA-factorial analysis showed that variations in the amounts of filamentous fungi are related to seasonal changes and the local characteristics and variations in counts of yeasts are mainly related to the characteristics of sites. The molecular analysis of yeast isolates revealed 70% of different morphotypes, and there was found less diversity in the river Tua. Molds and yeasts in particular, seem to respond to changes in aquatic ecosystems since they are influenced by pressures, either natural or anthropogenic.
Descrição
Dissertação de Mestrado em Engenharia do Ambiente
Palavras-chave
Leveduras , Poluição , Mineralogia , Hidroquímica , Bioindicadores