Vilmantas Preskienis

Postdoc

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Geography, geomorphology, and history are my favourite subjects, and within this broad spectrum, lakes and wetlands are of particular interest to me for several reasons: (1) they are hotspots of activity – water and waterlogged sediments support life of millions of microbial organisms that profit from a well-connected environment and warm, stable conditions; (2) they are mirrors of their environment – they exchange organic and inorganic matter with surrounding soils, forests, and the atmosphere. In this way studying changes in lakes enables us to understand well the changes in the whole environment in which they exist; (3) they collect data for us – by receiving matter from their environment, and by hosting life within, they slowly accumulate temporal information in their sediments. Therefore, while the data we collect from the water column and sediment surface can represent present conditions of the aquatic system (and its surrounding region), by studying deeper sediments, we can look how the conditions changed with time in the past.

Before coming to the Aquatic laboratory of Dr. Milla Rautio, I have worked with both peatlands and lakes within permafrost areas. During my graduate studies, I worked with plant macrofossils to understand better the history of peatlands and development of permafrost in Northern Europe. Later I arrived in Canada to join an interdisciplinary project seeking to explain the high measured variability of greenhouse gas (primarily CO2 and CH4) emissions from tundra water bodies located in a small study site, on Bylot Island, in Northern Canada.

 

My doctoral studies involved both thermokarst lakes and small tundra ponds located on continuous permafrost terrain. I deepened my knowledge in carbon cycling, including transportation of terrestrial organic matter into freshwater bodies, biogeochemical reactions within the water bodies, and carbon exchanges with the atmosphere. I have also tried to understand what makes an organic matter to be of high quality for microbial consumption.

Presently, I am working with several exciting projects with my colleagues in the Aquatic laboratory: (1) winter limnology in a boreal lake (Simoncouche) located close to Saguenay; (2) understanding present, past, and the future of lakes in Saskatchewan, in which environments span from taiga underlain by permafrost, to boreal forests, to grasslands, south of the southern tree line; (3) organic matter cycling in continuous permafrost environments poor in terrestrial organic matter content (Victoria Island, Nunavut).

 

For the first project we conducted a detailed spatio-temporal study of greenhouse gases throughout winter, as there is little known about CO2 and CH4 production, transportation, and emissions from lakes when they are covered with ice. For the second project, we sampled 20 lakes across the province of Saskatchewan from north to south, studying their eutrophication levels, greenhouse gas production, and sediment organic matter quality. This study involved both field sampling and lake sediment incubation experiments in the laboratory. Finally, the third project seeks to expand our knowledge of lake ecosystems located in barren Arctic, and to understand how organic matter cycling varies across the seasons and across these largely understudied permafrost landscapes.