Our research stay at the Tank lab was conducted from July 18th to 31th 2019. This scientific group is mainly focused on the study of freshwaters in Arctic and Boreal environments. Our stay enabled us to learn by first-hand their ongoing research projects and to establish fruitful connections that helped us to broaden our scientific perspectives.

During our stay, we also carried out fieldwork and laboratory experiments within the context of the project “Temperature sensitivities of biofilm enzymatic activities: a latitudinal experiment”. This project aims at better understanding the effect of warming in-stream microbes and their capacity to decompose organic matter. To do so, we are carrying out the same experiment in streams of other climate regions (i.e. Arctic, temperate, Mediterranean and tropical zones), along a worldwide latitudinal gradient. Thus, the inclusion of a Boreal site in Alberta will provide us a more complete view of the effects of temperature on microbial decomposition activities, which is relevant in a context of climate change.

In Canada, we selected a pristine stream located close to Edmonton (Happy Creek, Hinton) at the foothills of the Rocky Mountains. In the field, we first measured basic physicochemical parameters such as temperature, conductivity, dissolved oxygen and discharge (Fig. 1). We then collected water samples for analyses of conventional water chemistry parameters (i.e. nutrients, dissolved organic matter, metals), and, finally, we collected some representative stream cobbles (Fig. 1). We were particularly interested in the biofilm developing on these cobbles, which is a thin mucous layer that contains a really diverse and active community of microorganisms.

Once at Tank’s lab, we scraped the microbial community on the cobbles and incubated the slurry at five temperatures (4, 8, 16, 24 and 32ºC) and with six different fluorescent substrates to assess the extracellular enzymatic activities (Fig. 2). These enzymes decompose organic compounds (e.g. leaf litter) and generate smaller compounds that can be acquired by the microorganisms. Thus, extracellular enzymes play a key ecological role in the transformation and mineralization of organic matter.

During our stay, we learned about the research conducted by Tank’s group members, mostly master and PhD students (Fig. 3). They explained to us their ongoing experiments, the techniques and instruments being used, and the challenges of the fieldwork in high-latitude ecosystems. We could share our experiences in Canada and Greenland and discuss about future research directions.

We greatly thank the North2North Programme to make possible our stay at University of Alberta, which was both an exceptional scientific and life experience.


Pau and Ada