Browsing by Author "Haupt, Evan"

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    Methanotrophic Bacteria and Biogeochemical Cycling in an Oil Sands End Pit Lake
    (2016) Haupt, Evan; Dunfield, Peter; Voordouw, Gerrit; Gieg, Lisa; Strack, Maria; Else, Brent
    This study examined for the first time the microbial community and biogeochemical cycling of methane and oxygen in Base Mine Lake, the reclamation site of a former tailings pond in the Athabasca oil sands region of Northern Alberta. Base Mine Lake represents the first large-scale demonstration of the “water-capped end pit lake” approach to tailings pond reclamation, with the ultimate goal of transitioning the lake into a natural, self-sustaining ecosystem. The oxygenated upper portion of the lake is home to aerobic hydrocarbon degrading bacteria, including a diverse population of methane oxidizing bacteria, whose activity, dispersion, and community composition is greatly influenced by seasonal variation. The majority of methanotrophs in the lake belong to the class Gammaproteobacteria, although Alphaproteobacteria methanotrophs make up a relatively large percentage of methanotrophs during summer stratification. Methanotroph abundance and potential for methane oxidation are relatively high during periods of turnover or partial mixing in the lake, and decrease during stratification.
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    Seasonal dynamics of methanotrophic bacteria in a boreal oil sands end-pit lake
    (2021-11-29) Albakistani, Emad; Nwosu, Felix; Furgason, Chantel; Haupt, Evan; Smirnova, Angela; Verbeke, Tobin; Lee, Eun-Suk; Kim, Joong-Jae; Chan, Amelia; Ruhl, Ilona; Sheremet, Andriy; Rudderham, Sarah; Lindsay, Matthew; Dunfield, Peter
    Base Mine Lake (BML) is the first full-scale demonstration end pit lake for the oil sands mining industry in Canada. We examined aerobic methanotrophic bacteria over all seasons for five years in this dimictic lake. Methanotrophs comprised up to 58% of all bacterial reads in 16S rRNA gene amplicon sequencing analyses (median 2.8%), and up to 2.7 × 104 cells mL−1 of water (median 0.5 × 103) based on qPCR of pmoA genes. Methanotrophic activity and populations in the lake water were highest during fall turnover, and remained high through the winter ice-covered period into spring turnover. They declined during summer stratification, especially in the epilimnion. Three methanotroph genera (Methylobacter, Methylovulum, and Methyloparacoccus) cycled seasonally, based on both relative and absolute abundance measurements. Methylobacter and Methylovulum populations peaked in winter/spring, when methane oxidation activity was psychrophilic. Methyloparacoccus populations increased in the water column through summer and fall, when methane oxidation was mesophilic, and also predominated in the underlying tailings sediment. Other, less abundant genera grew primarily during summer, possibly due to distinct CH4/O2 microniches created during thermal stratification. These data are consistent with temporal and spatial niche differentiation based on temperature, CH4 and O2. This pit lake displays methane cycling and methanotroph population dynamics similar to natural boreal lakes. Importance statement: The study examined methanotrophic bacteria in an industrial end pit lake, combining molecular DNA methods (both quantitative and descriptive) with biogeochemical measurements. The lake was sampled over 5 years, in all four seasons, as often as weekly, and included sub-ice samples. The resulting multi-season and multi-year dataset is unique in its size and intensity, and allowed us to document clear and consistent seasonal patterns of growth and decline of three methanotroph genera (Methylobacter, Methylovulum, and Methyloparacoccus). Laboratory experiments suggested that one major control of this succession was niche partitioning based on temperature. The study helps to understand microbial dynamics in engineered end-pit lakes, but we propose that the dynamics are typical of boreal stratified lakes, and widely applicable in microbial ecology and limnology. Methane oxidising bacteria are important model organisms in microbial ecology, and have implications for global climate change.