Call for SITES AquaNet-AQUACOSM-plus experiment

Functional and compositional consequences of run-off variability on plankton communities

Photo: Leif Klemedtsson. Photo: Leif Klemedtsson.

SITES AquaNet and AQUACOSM-plus have an open call to invite research groups, individual researchers and trainees to apply to join a coordinated mesocosm experiment in 2022 at all five SITES stations participating in SITES AquaNet! 

To apply and find additional information visit the AQUACOSM website. Application deadline is 28 February 2022. 

We hope to involve many national and international researcher and students in the planning, implementation and analysis of the experiment. Join us in this exiting mission of running a large, coordinated experiment!

Transnational Access

AQUACOSM-plus provides Transnational Access (TA) free of charge to approved users to at least one of the partner facilities, including costs for travel, housing and meal expenses.



Please contact us if you have questions about the experiment and/or would like to apply.

•    Silke Langenheder (
•    Nils Kreuter (


Environmental change encompasses stochastic to periodic fluctuations in environmental conditions, gradual environmental changes as well as pulse events, i.e. abrupt and unpredictable changes in ecological parameters. The latter become more important in many ecosystems as a result of increasing intensities and frequencies of extreme weather events due to climate change. Lakes, for example, will experience heavier and flashier rainfalls, storm-induced mixing and prolonged drought periods in summer. This will result in increased variability in resources (nutrient and carbon) available to plankton communities, which can potentially alter ecosystem process rates as well as biomass and community composition, stoichiometry, diversity and temporal turnover across multiple trophic levels. 
In general, global change research has to a large extent focused on altered mean environmental conditions, whereas the importance of stochastic event driven dynamics and their characteristics, such as their intensities, frequencies, timing, and chronology are less studied. This, despite that fact that stochastic event driven dynamics may be more important for ecological communities and ecosystem processes than long-term changes in mean conditions (e.g. Jentch et al 2007).
To manage the effects of increasing extreme weather events there is a further need to know if the effects are persistent over different types of lakes or if local lake characteristics and climate strongly affect the response. For example, ecosystem responses to nutrient perturbations and storms can be mediated by interactions with foundation species, fish presence and abiotic components of ecosystems (e.g. Cottingham and Schindler, 2000, Thanyne et al. 2021, Lüring et al. 2021). To address such questions, spatially coordinated experiments that look at responses to standardised manipulations with standardized equipment and methods are crucial tools. SITES AquaNet is well suited in this regard since the program is designed to implement standardized experiments across lakes. Moreover, the mesocosms in SITES AquaNet are equipped with a high frequency sensor system for high-resolution measurements of phytoplankton and cyanobacterial biomass and ecosystem metabolism, such as primary production and respiration, at various time scales.

The overarching aims of the coordinated experiment are as follows:
(a)   To test if the addition of a constant amount of resource (i.e. organic and inorganic nutrients), in pulses that differ in intensities and frequencies over a given time period, lead to differences in plankton composition and function.
(b)  If the effects of the addition are persistent across lakes as well as different trophic groups and ecosystem functions and if not, to identify which properties (e.g. local abiotic and biotic factors) are the cause.

Experimental set-up

We will investigate effects of different run-off scenarios focusing particularly on differences in resource (nutrient/carbon) pulse variability over a given time period. This will be done by manipulating selected characteristics of resource pulses (e.g. intensity, frequency, chronology) that are added to the mesocosms while keeping the total amount of added nutrients and organic carbon constant. The selected scenarios will be designed to reflect natural precipitation/runoff scenarios informed by long-term monitoring data available from the SITES stations. To see if effects of nutrient pulse manipulations persist beyond the simulated rainfall period, the experiment  will ‘simulate’ a rainfall period lasting for approximately 3-4 weeks, followed by a recovery period of approximately 1-2 weeks.

Time plan
The experiment will run for 6-7 week from the beginning of July to mid-August. This includes time for preparations and training, mesocosm and sensor installations, and cleaning up the experiment. The running time of the experiment is approximately 5 weeks. Up to 6 users are expected at each station.

More information and details about the experimental set-up: 

Detailed experimental procedures.pdf (This document will be regularly updated, last update 2021-11-16)


Cottingham, K.L. and Schindler D.E. (2000) Effects of grazer community structure on phytoplankton response to nutrient pulses. Ecology 81: 183-200.
Jentsch, A., Kreyling, J, and Beierkuhnlein (2007). A new generation of climate-change experiments: events, not trends. Front Ecol Environ 5: 365-374.
Lürig, M. D., A. Narwani, H. Penson, B. Wehrli, P. Spaak, and B. Matthews. 2021. Non-additive effects of foundation species determine the response of aquatic ecosystems to nutrient perturbation. Ecology 102(7):e03371. 10.1002/ecy.3371
Thayne, M.W., Kraemer, B.M., Mesman, J.P., Adrian, R. and Iberlings, B.W. (2021) Antecedent lake conditions shape resistance and resilience of a shallow lake ecosystem following extreme wind storms. Limnol. Oceanogr