Microbial Community Shifts in Response to Acid Mine Drainage Pollution Within a Natural Wetland Ecosystem

Abstract

Natural wetlands are known to play an important role in pollutant remediation, such as remediating acid mine drainage (AMD) from abandoned mine sites. However, many aspects of the microbiological mechanisms underlying AMD remediation within wetlands are poorly understood, including the role and composition of associated microbial communities. We have utilized an AMD-polluted river-wetland system to perform rRNA sequence analysis of microbial communities that play a role in biogeochemical activities that are linked to water quality improvement. Next-generation sequencing of bacterial 16S rRNA gene amplicons from river and wetland sediment samples identified variation in bacterial community structure and diversity on the basis of dissolved and particulate metal concentrations, sediment metal concentrations and other water chemistry parameters (pH and conductivity), and wetland plant presence. Metabolic reconstruction analysis allowed prediction of relative abundance of microbial metabolic pathways and revealed differences between samples that cluster on the basis of the severity of AMD pollution. Global metabolic activity was predicted to be significantly higher in unpolluted and wetland sediments in contrast to polluted river sediments, indicating a metabolic stress response to AMD pollution. This is one of the first studies to explore microbial community structure dynamics within a natural wetland exposed to AMD and our findings indicate that wetland ecosystems play critical roles in maintaining diversity and metabolic structure of sediment microbial communities subject to high levels of acidity and metal pollution. Moreover, these microbial communities are predicted to be important for the remediation action of the wetland.

The association of microbial activity with Fe, S and trace element distribution in sediment cores within a natural wetland polluted by acid mine drainage

“…2a). This confirms the acidity attenuation detected over 20 years of monitoring at this site (Dean et al, 2013;Aguinaga et al, 2018). Significant differences in Fe and S concentrations were also observed across the wetland sites.…”

“…Site W1 was located at ~500 m from the AMD source and is where the attenuation process starts. Site W2 was located in the zone where the large decrease in acidity and dissolved metal(loid) concentration have previously been observed, while site W3 was located in the lower reaches of the wetland where pollution levels are significantly reduced (Dean et al, 2013;Aguinaga et al, 2018).…”

“…The study site for this investigation was the Afon Goch Wetland in Anglesey, UK that receives highly polluted AMD (pH 2.5) and removes >80% of dissolved Fe, Zn and Cu and increases pH to 5.5 within the first 700 m of the wetland system (Dean et al, 2013). Previous characterization of the Afon Goch wetland suggests that the remediation process is mediated by precipitation of metal(loid)s and accumulation of metal(loid)s in the sediment, and due to a combination of chemical and biological processes (Boult, 1996;Batty et al, 2006;Dean et al, 2013;Aguinaga et al, 2018). However, the activities of specific bacteria related to S and Fe metabolism in association with a detailed analysis of sediment metal(loid) profiles are needed to begin to elucidate these biological processes.…”

Metabolic adaptation of a Chlamydomonas acidophila strain isolated from acid mine drainage ponds with low eukaryotic diversity

“…The main aim of this study was to identify microorganisms from the open, standing waters of the AMD ponds. Some of the ponds were surrounded by vegetation including wetland plant species, which will harbor associated microorganisms (Aguinaga et al, 2018).…”

Bacterial dominance is due to effective utilisation of secondary metabolites produced by competitors

“…reduced or increased competition 2,13,14 ), due to changing resource utilisation, and the diversity of the system, through changing selection pressures (e.g. bioremediation of a toxin 15 ). As such, one study also utilised 1 H NMR to look at the effect of shared resources, and complimentary interactions (e.g.…”