THE SUCCESSION OF UNSUNG HEROES BENEATH OUR FEET; THE STUDY OF PRIMARY SUCCESSION IN A SHALLOW FRACTURED AQUIFER (COVEY HILL, QUEBEC, CANADA)

Aquifers in the continental subsurface have long been exploited for their resources. However, given the technical difficulties in accessing recurring subsurface samples, the communities of microorganisms living there and their temporal dynamics remain largely misunderstood. Here, we investigated the effects of time and organic and inorganic carbon on primary succession of microorganisms belonging to the Bacteria and Eukaryote domains colonizing rock surfaces from a shallow fractured aquifer. We recreated its physicochemical environment in triplicate bioreactors and let the communities grow for 24 days. The planktonic and sessile communities were sampled daily in independent experiments and characterized based on their 16S (Bacteria) or 18S (Eukaryote) rRNA genes. Time was the parameter with the strongest correlation both with alpha and beta diversity and the first few days of the incubations fluctuated more in composition than the latter days. Eukaryotes were mainly photosynthetic despite growing in the dark and Bacteria were mostly heterotrophs. The alpha diversity of planktonic and sessile communities varied following similar patterns, but the planktonic ones varied with a wider amplitude. Also, the early day planktonic communities, especially the eukaryotes, were more like the ones of the latter days than the mid-incubation ones. Finally, organic and inorganic carbon played a much smaller role than expected as we believe other parameters such as pH and light limited microorganism growth.

Presentation Preference: Oral

Primary Presenter: Samuel beauregard-tousignant, UQAM - GRIL (samuel.beauregard.t@gmail.com)

Authors:

Samuel Beauregard-Tousignan, UQAM GRIL  (samuel.beauregard.t@gmail.com)

Cassandre Lazar, UQAM GRIL  (lazar.cassandre@uqam.ca)