Browsing by Author "Staebe, Karin"

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    Determination of the bacterial diversity of a natural freshwater wetland impacted by acid mine drainage.
    (Stellenbosch : Stellenbosch University, 2015-12) Staebe, Karin; Cloete, T. E.; Oberholster, P. J.; Stellenbosch University. Faculty of Science. Dept. of Microbiology.
    ENGLISH ABSTRACT: Freshwater resources in semi-arid countries, such as South Africa, are under constant threat from pollution. One of the major pollutants is acid mine drainage, which not only lowers the pH of the water, but also increases sulphate and metal concentrations. Primary producers, such as bacteria and algae, are the first organisms to respond to stressors such as reduced pH and elevated sulphate and metal concentrations. A natural freshwater wetland, the Zaalklapspruit wetland in Mpumalanga, impacted by acid mine drainage and industrial effluent was studied to determine the change in algal and bacterial populations. Five study sites were identified including a reference site and four sites displaying various degrees of degradation. Physical and chemical parameters were measured at each site. Algae were identified microscopically and chlorophyll-a concentrations were measured. The algal species present at the five study sites were species previously associated with the conditions present at the various sites. Gyrosigma rautenbachiae proved to be an ideal bioindicator for industrial pollution. The diatom species Synedra ulna, Nitzschia spp. and Cymbella spp. were found at the acidic sites. The filamentous green algae Microspora quadrata and Klebsormidium acidophilum were abundant at the sites the most impacted by AMD. Metal tolerant K. rivulare were also identified in this study. The cyanobacteria Oscillatoria tenius and Glaucospira sp. were associated with enriched conditions. The bacterial populations were sampled from both the water column and sediment and subjected to next generation sequencing for identification. The phyla that were highly represented throughout all the samples were the alpha-, beta- and gamma-Proteobacteria, Bacteriodetes and unclassified species. The Bacteriodetes phylum was observed at significantly higher numbers at sites 1, 2, 3 & 5 in the March 2013 water samples and sites 1 & 4 in the March 2013 sediment samples. Firmicutes had significantly higher numbers at sites 2 (January 2013), 3 (March 2013) & 4 (January 2013) in the water samples. Both water and sediment samples of sites 2 (March 2013) & 4 (January 2013) had significantly higher numbers of Actinobacteria. The Chloroflexi phylum had significantly higher numbers in the site 4 & 5 (January 2013) water samples and site 5 (January 2013) of the sediment samples. Acidobacteria were only detected in significantly higher numbers in the January 2013 sediment samples of sites 1 & 5. This study was the first to assess the total bacterial diversity in a natural, acid mine drainage impacted wetland in South Africa and also the first to identify sequences from the genus Marinobacterium. The wetland ecosystem health was also determined using a rapid bioassessment tool and a proposed bacterial bioindicator. The bioassessment tool scored the reference site as mostly natural, two sites as severely modified and the last two as modified. The proposed bacterial bioindicator was simplistic in use and reflected the stability of the populations at the five sites accordingly. Lastly, the bacterial bioindicator was incorporated into the established bioassessment tool and was found to correspond with the latter’s results.