Microbial community development in an oil sands pit lake

Area of Science:

• Environmental microbiology
• Ecosystem reclamation
• Oil sands industry impacts

Background:

• Fluid tailings from Canadian oil sands mining pose environmental risks.
• Pit Lakes (PLs) are a reclamation strategy to contain and remediate tailings.
• The goal is for PLs to eventually support boreal lake food webs.

Purpose of the Study:

• To monitor microbial communities in an oil sands pit lake (Base Mine Lake, BML) over six years.
• To compare BML microbial communities to a freshwater reservoir and active tailings ponds.
• To assess the progression of microbial community development in a PL.

Main Methods:

• 16S/18S rRNA gene amplicon sequencing and metagenomics.
• Monitoring prokaryotic and eukaryotic microbes.
• Comparative analysis of microbial diversity and community structure.

Main Results:

• BML microbial communities were consistently intermediate between tailings ponds and freshwater controls.
• Communities exhibited high variability with season, depth, and year, lacking core species found in freshwater.
• Indicator species for both tailings (hydrocarbon degraders, sulfur cyclers) and freshwater (phototrophs) were abundant in BML.

Conclusions:

• BML microbial communities represent a transitional state between tailings and natural freshwater systems.
• The PL supports food webs incorporating elements from both environments.
• Microbial communities in BML have not stabilized within the first ten years of its creation.