Project 6

Effect of storm events on microbial dynamics and ecosystem functions in lakes.

Based in: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany.

Objectives: it is still unknown how extreme weather events such as storms will affect a lake’s function as a carbon source or sink. Current estimates suggest that lakes globally emit between 8–48 Tg of methane per year (equivalent to 6–16% of total natural methane emissions) which is greater than oceanic methane emission. There are indications that extreme events such as storms can severely alter greenhouse gas dynamics as well as phytoplankton and microbial dynamics. The LakeLab mesocosms (www.lake-lab.de/) provide a near-ecosystem model since they are fully equipped with automatic profilers allowing for a high temporal and spatial monitoring of all important limnological variables including phytoplankton dynamics. For example, a preliminary experiment, mimicking a storm event in July 2014, led to the formation of a massive cyanobacterial bloom (Dolichospermum flos-aquae) which resulted in alteration of microbial dynamics and hence C-cycling, and in particular changes in calcite precipitation rendering the lake from a C-sink to a C-source. The overall objective of this project is to study the microbial response to simulated extreme events in different seasons to better evaluate their effects in both the productive (summer) and less productive (winter) seasons. Specific objectives include:

  • To carry out a set of experiments informed by current/projected intensity and duration of extreme events at MANTEL sites.
  • To collect and collate profiler data (temperature, pH, conductivity, oxygen, PAR, pigments, turbidity etc.).
  • Observe changes in the microbial community structure (next generation sequencing and microscopic counts) and activities (gross primary production, net ecosystem respiration, bacterial production, sedimentation and whole lake metabolism). 

Using these data, evaluate whether future storm events have the potential to significantly alter ecosystem dynamics and function rendering lakes from C-sources to C-sinks. 

This student will be primarily based in Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany supervised by Prof. Hans Peter Grossart and will be co-supervised by and spend study time with Dr Eleanor Jennings, Dundalk Institute of Technology, Ireland. The PhD will be co-awarded by University of Potsdam and Dublin City University.