Project 2

Effects of major weather events on the relationship between carbon emissions and aquatic heterotrophy in lakes.

Based in: University of Barcelona, Spain

Objectives: the metabolism of lakes and reservoirs has received major attention in the last decade to understand net heterotrophy derived from terrestrial organic matter inputs and the role of inland waters as carbon (C) sources to the atmosphere. Processes other than aquatic metabolism have been recently highlighted as major drivers of C emissions, e.g. hydrological inputs of inorganic C from different sources. While this is a topic under debate, most of the contributions to this have relied on low-frequency approaches. This contrasts with evidence on the fast response of aquatic ecosystem functioning or C cycling to major yet infrequent weather-related events, either in terms of community composition, metabolism, and carbon fluxes, or of fast organic matter transport downstream the fluvial networks (Pulse-shunt concept). The overarching aim of this project is to understand the effect of weather-derived events on the contribution of aquatic ecosystem metabolism to lake and reservoir C fluxes at short time scales. It includes major water inputs after high rainfall events, fast changes in mixing dynamics and ice-off events. Planned secondments with the co-supervisor team will ensure the PhD student gets the necessary skills on lake metabolism and gas flux calculations, modelling of catchment hydrology and management and analysis of HFM data. The analysis of in-lake high-frequency data in contrasting catchments (lithology and land uses) combined with model-derived data for organic matter transport and processing along the fluvial network and in situ monitoring of gas fluxes is the basis for this project, which aims at discerning purely physical and hydrological effects of rainfall events from internal responses based on changing ecosystem functioning.

This student will be primarily based in University of Barcelona supervised by Dr Biel Obrador, and co-supervised by and spend study time with Dr Alo Laas, Estonian University of Life Sciences, Tartu, Estonia. The PhD will be a double award given by University of Barcelona (ES) and Estonian University of Life Sciences (EE).