Does time drive space? First meeting of the sTURN working group



We had a productive first meeting of our working group at the sDiv  in Leipzig. Thanks to our hosts in Leipzig and to all group members for an exciting week! Loads of work ahead…;-)

zs & rpt


Open call for a PhD student

We are looking for a highly motivated MA with a background in molecular methods and/or aquatic microbial ecology, to do a PhD in collaboration with Mia M. Bengtsson (University of Greifswald, DE) and Stella Berger (IGB Stechlin, DE) on mixotrophic bacterivorous protists. The position is available within the DFG/FWF jointly funded project LakeMix.

The position is to be filled as soon as a suitable candidate is found.

Starting date is January 2018.

Interested candidates should contact Robert Ptacnik by email at robert.ptacnik(at)


Collaborate with us on an experimental test of the spatial insurance hypothesis

AQUACOSM enables us to invite external researchers to collaborate with us on the research outlined below (see How to get involved, below). Depending on positive evaluation of your application, AQUACOSM covers your travel and accomodation for the time of the experiment,as well as local resources (lab space, consumables etc). Please don’t hesitate contacting us for questions or support with the proposal. Find application guidelines here (pdf).


In the experiment scheduled for June-July 2018, we want to test the spatial insurance hypothesis in a mesocosm experiment, where we expose natural plankton communities to a connectivity x heat disturbance treatment (C x T; Fig 1).


for Aquacosm

Fig 1: Schematic representation of the planned experiment. (a) Short description and timing of treatments, where the duration of ‘T’ is highlighted with red, while the timing of ‘CM‘ and ‘CZ‘ are indicated with arrows on a time scale bar. (b) Sketch of the experimental design where cylinders represent the mesocosms with 5 replicates for each treatment combinations.

Mesocosm will be inoculated with natural plankton communities. Connectivity to a regional species pool will be manipulated by regular additions of water from natural lakes to +C treatments (microorganism and zooplankton dispersal will represent separate treatments), while -C treatment receive no further dispersal . An intermittent heat wave will be induced by heating +T mesocosms 5°C for one week, while -T treatments will stay with ambient temperature.

In a previous experiment, we showed that plankton communities in mesocosms respond sensitively to connectivity even without disturbance (Fig 2).

Hypotheses: By involving a disturbance treatment, we want to test if (a) disturbance-induced community turnover is sensitive to connectivity and (b) resilience depends on connectivity (resilience will be monitored in terms of biomass over time in different functional groups, esp. phyto- and zooplankton).

How to get involved: We would especially welcome collaborators interested in BEF relationships of plankton communities, but also microbial/molecular diversity. As ciliates turned out to be highly sensitive to manipulation of connectivity in a previous experiment, we would also welcome experts on micrograzers. And of course we are open for suggestions regarding topics not included by now. Depending on your state of career, you can participate as a trainee or researcher, team or individual.



Fig 2: Effects of connectivity (C) on taxon richness of bacteria and protists in a previous mesocosm experiment. Richness of +C treatments (y-axis) plotted against richness in -C treatments (x-axis). (Bengtsson, Eggers et al in prep.)