Incorporating Microbes into Environmental Monitoring and Mine Closure Programs: River Diversions as Test Beds.
Blanchette, Melanie Lise (1); Lund, Mark Andrew (1); Moore, Michael (2); Short, Digby (3)
1: Mine Water and Environmental Research Centre (MiWER), School of Science, Edith Cowan University, Perth, Australia; 2: Yancoal Australia Ltd., Sydney, NSW, Australia; 3: Ashton Coal (Yancoal Australia), Singleton, NSW, Australia
Microbes have the potential to be more cheaply and rapidly analysed than traditional bioendpoints (e.g., macroinvertebrates). However, there has yet to be a broad effort to incorporate microbes into river assessment and closure programs because their ecology is not well-understood and methods are not standard. Therefore, the aims of this paper are to 1) determine if microbes (Archaea and Bacteria) correlate to environmental condition in mine-affected rivers, 2) apply the ‘system variability’ approach (below) to closure using microbial assemblages, and 3) develop standardised collection protocols for riverine microbes.
Previously, we proposed a closure model (the ‘system variability’ approach) for setting rehabilitation goals and evaluating the condition of highly modified environments without reference sites and pre-impact data. This model used multivariate statistics to compare rehabilitated sites to overall local ecosystem variability, rather than reference site characteristics. We tested the model using biophysical data from river diversions in the Hunter Valley, New South Wales, Australia, and found that data from diverted and non-diverted sections of river were significantly different, potential management actions could be identified, and site trajectories were mapped – in some instances towards closure. In this research, we extended our model to test microbial assemblages as bioindicators of environmental condition.
The research occurred in the two river systems as above (Goulburn River; GR and Bowman’s Creek; BC) at 32 sites (BC; 12 sites, GR; 20 sites) sampled over an annual hydroperiod (2016-2017, GR; four times, BC; twice). GR had a trapezoidal channel, whereas the BC diversion had been constructed with more ‘natural’ attributes. We collected physico-chemical variables (water and sediment chemistry, in-stream and riparian measurements) and samples for microbial diversity (pelagic, benthic sediment, benthic algal mat). DNA was extracted, sequenced and identified (Illumina MiSeq, QIIME 1.8, Greengenes). Data analysis (multivariate ordination, hypothesis testing using PERMANOVA) was as per the system variability model of closure.
Results indicated that microbial assemblages correlated with environmental variables (Aim 1), and there was a spatial and temporal effect on assemblage variability (Aim 2). The standardised collection protocol was adaptable to different benthic characteristics, and user-friendly (Aim 3). Our sampling methods for this project combined classic ecological techniques with novel environmental genomics and closure criteria, adding depth to monitoring protocols and increasing understanding of local microbially-mediated processes. However, more research is needed to understand the ecology of riverine microbial assemblages before they can be incorporated into monitoring and closure programs.