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 Department of Ecoscience Research/Consultancy Research facilities Lake Warming Mesocosm experiment

The Lake Warming Mesocosm experiment

The mesocosms have been used for climate-related short-term and seasonal experiments with animals and submerged macrophytes. Photo: Lone Liboriussen ©

Our mesocosm based climate change experiment is unique and is, in fact, the longest running climate experiment in the world. The set-up is adapted to future climate scenarios and uniquely allows for making realistic predictions about the impacts of the future climate change on our lakes.

The artificial lakes (mesocosms) consist of 24 stainless steel tanks (2800 l), which simulate shallow lakes. The lakes were established in a highly standardised way in 2003 with 30 cm standard lake sediment added to each tank as well as a 1 m water column, which was inoculated with a natural freshwater community of algae, small animals, zooplankton and sticklebacks from both nutrient-poor and nutrient-rich lakes. Submerged macrophytes were introduced together with the sediment. The mesocosms are treated with three temperatures and two nutrient levels yielding four tanks with the exact same treatment combination. Heating is done with electrical heating elements placed at the bottom and, depending on season and treatment, the heating follows the IPCC’s A2 scenario of 2.5 to 6.6 °C above the unheated temperature (control). From 2003 to 2023 there were no changes in the experimental treatments, however in 2023 the nutrient treatments were reversed allowing us to track the effects of increasing and decreasing nutrient loading at different temperatures.

From the start of the experiment temperature, dissolved oxygen and pH were measured at high frequency. In recent year, thanks to funding from AnaEE and AQUACOSM, other high frequency measurements have been added. Chlorophyll (algal pigments) and phycocyanin (blue-green algal pigment) sensors now record algal biomass at high temporal resolution. This allowed a comparison of standard methods with new sensor based approaches (Link to paper: https://open-research-europe.ec.europa.eu/articles/4-69/v3).

In addition, a low cost, bespoke system developed together with engineers at AU measures carbon dioxide and methane fluxes six times daily, this supplements previous lower resolution studies (see the publication list).

The mesocosm facility is now part of the Danish and European wide AnaEE project , included in the European AnaEE list of experimental facilities for ESFRI. The facility was part of EU Horizon 2020 projects  PONDERFUL and AQUACOSM plus, the latter funded over 1400 days of transnational access to the facility over 8 years. Currently we are part of two EU projects offering transnational access (support for researchers to come and work at the mesocosms as part of IRISCC and Agroserv.

We are hoping to expand the system in include stream flumes in the near future, watch this space. 

Publications List

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Jeppesen, E., He, H., Søndergaard, M., Lauridsen, T. L., Davidson, T. A., Levi, E. E. & McCarthy, M. J. (2025). Experimental evidence of the role of nitrogen for eutrophication in shallow lakes: A long-term climate effect mesocosm study. Innovation, 6(4), Article 100756. https://doi.org/10.1016/j.xinn.2024.100756
Meirkhanova, A., Zhumakhanova, A., Len, P., Schoenbach, C., Levi, E. E., Jeppesen, E., Davidson, T. A. & Barteneva, N. S. (2025). Heatwave-Induced Thermal Stratification Shaping Microbial-Algal Communities Under Different Climate Scenarios as Revealed by Long-Read Sequencing and Imaging Flow Cytometry. Toxins, 17(8), Article 370. https://doi.org/10.3390/toxins17080370
Audet, J., Levi, E. E., Jeppesen, E. & Davidson, T. A. (2025). Nutrient enrichment—but not warming—increases nitrous oxide emissions from shallow lake mesocosms. Limnology and Oceanography, 70(S2), S43-S54. https://doi.org/10.1002/lno.12709
Stamenković, O., Pacheco, J. P., Levi, E. E., Jeppesen, E. & Davidson, T. A. (2025). Nutrient inversion but not warming drive changes in periphyton biomass and composition in shallow lake mesocosms. Limnology and Oceanography, 70(S2), S140-S154. https://doi.org/10.1002/lno.70053
van't Veen, S. G. M., Kronvang, B., Audet, J., Davidson, T. A., Jeppesen, E., Kristensen, E. A., Larsen, S. E., Laugesen, J. R., Levi, E. E., Nielsen, A. & Andersen, P. M. (2025). SentemQC - A novel and cost-efficient method for quality assurance and quality control of high-resolution frequency sensor data in fresh waters. Open Research Europe, 4(244), Article 244. https://doi.org/10.12688/openreseurope.18134.2
Levi, E. E., Jeppesen, E., Nejstgaard, J. C. & Davidson, T. A. (2024). Chlorophyll-a determinations in mesocosms under varying nutrient and temperature treatments: in-situ fluorescence sensors versus in-vitro measurements. Open Research Europe, 4, Article 69. https://doi.org/10.12688/openreseurope.17146.1
Zhumakhanova, A., Mirasbekov, Y., Meirkhanova, A., Malashenkov, D. V., Davidson, T. A., Levi, E. E., Jeppesen, E. & Barteneva, N. S. (2024). From colonial clusters to colonial sheaths: Imaging flow cytometry analysis of Microcystis morphospecies dynamics in mesocosm and links to CyanoHABs management. Ecological Indicators, 163, Article 112100. https://doi.org/10.1016/j.ecolind.2024.112100
Yuan, G., Levi, E. E., Davidson, T. A., Lauridsen, T. L., Søndergaard, M., Yang, Z., Wu, A., Cao, T., Li, Y., Fu, H. & Jeppesen, E. (2024). Warming alters the network of physiological traits and their contribution to plant abundance. Science of the Total Environment, 939, Article 173573. https://doi.org/10.1016/j.scitotenv.2024.173573
Esposito, C., Nijman, T. P. A., Veraart, A. J., Audet, J., Levi, E. E., Lauridsen, T. L. & Davidson, T. A. (2023). Activity and abundance of methane-oxidizing bacteria on plants in experimental lakes subjected to different nutrient and warming treatments. Aquatic Botany, 185, Article 103610. https://doi.org/10.1016/j.aquabot.2022.103610
Tavşanoğlu, Ü. N., Çırak, T., Başaran Kankılıç, G., Ongun Sevindik, T., Nadir Solak, C., Pacheco, J. P., Levi, E. E. & Davidson, T. A. (2023). Impacts of plastic surface on the periphyton under different nutrient and temperature: A mesocosm experiment. Abstract from 3rd International Symposium on Aquatic Mesocosm-Based Research, Antalya, Turkey.
Dashkova, V., Malashenkov, D. V., Baishulakova, A., Davidson, T. A., Vorobjev, I. A., Jeppesen, E. & Barteneva, N. S. (2022). Changes in Phytoplankton Community Composition and Phytoplankton Cell Size in Response to Nitrogen Availability Depend on Temperature. Microorganisms, 10(7), Article 1322. https://doi.org/10.3390/microorganisms10071322
Strandberg, U., Hiltunen, M., Syväranta, J., Levi, E. E., Davidson, T. A., Jeppesen, E. & Brett, M. T. (2022). Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities: A mesocosm experiment. Science of the Total Environment, 843, Article 157001. https://doi.org/10.1016/j.scitotenv.2022.157001
Pacheco, J. P., Aznarez, C., Levi, E. E., Baattrup-Pedersen, A. & Jeppesen, E. (2022). Periphyton responses to nitrogen decline and warming in eutrophic shallow lake mesocosms. Hydrobiologia, 849(17-18), 3889-3904. https://doi.org/10.1007/s10750-021-04755-y
Jeppesen, E., Audet, J., Davidson, T. A., Neif, É. M., Cao, Y., Filiz, N., Lauridsen, T. L., Larsen, S. E., Beklioğlu, M., Sh, T. & Søndergaard, M. (2021). Nutrient loading, temperature and heat wave effects on nutrients, oxygen and metabolism in shallow lake mesocosms pre-adapted for 11 years. Water (Switzerland), 13(2), Article 127. https://doi.org/10.3390/w13020127
Esposito, C., Nijman, T. P. A., Audet, J., Veraart, A. J., Levi, E. E. & Davidson, T. A. (2021). Patterns and processes of CH4 production and oxidation in different habitats from experimental lakes on a gradient of temperature and nutrients. Abstract from Shallow Lakes Conference 2021.
Mirasbekov, Y., Zhumakhanova, A., Zhantuyakova, A., Sarkytbayev, K., Malashenkov, D. V., Baishulakova, A., Dashkova, V., Davidson, T. A., Vorobjev, I. A., Jeppesen, E. & Barteneva, N. S. (2021). Semi-automated classification of colonial Microcystis by FlowCAM imaging flow cytometry in mesocosm experiment reveals high heterogeneity during seasonal bloom. Scientific Reports, 11, Article 9377. https://doi.org/10.1038/s41598-021-88661-2
Nijman, T. P. A., Davidson, T. A., Weideveld, S. T. J., Audet, J., Esposito, C., Levi, E. E., Ho, A., Lamers, L. P. M., Jeppesen, E. & Veraart, A. J. (2021). Warming and eutrophication interactively drive changes in the methane-oxidizing community of shallow lakes. ISME Communications, 1, Article 32. https://doi.org/10.1038/s43705-021-00026-y
Işkın, U., Filiz, N., Yu, C., Machado, É. M. N., Öglü, B., Lauridsen, T. L., Davidson, T. A., Jørgensen, M. S., Tavsanoglu, U. N., Beklioglu, M. & Jeppesen, E. (2020). Impact of Nutrients, Temperatures, and a Heat Wave on Zooplankton Community Structure: An Experimental Approach. Water, 12(12), 1-19. Article 3416. https://doi.org/10.3390/w12123416, https://doi.org/10.3390/w12123416
Filiz, N., Işkın, U., Beklioglu, M., Öglü, B., Davidson, T. A., Jørgensen, M. S., Lauridsen, T. L. & Jeppesen, E. (2020). Phytoplankton Community Response to Nutrients, Temperatures, and a Heat Wave in Shallow Lakes: An Experimental Approach. Water, 12(12), Article 3394. https://doi.org/10.3390/w12123394
Zhou, Y., Zhou, L., Zhang, Y., Garcia de Souza, J., Podgorski, D. C., Spencer, R. G. M., Jeppesen, E. & Davidson, T. A. (2019). Autochthonous dissolved organic matter potentially fuels methane ebullition from experimental lakes. Water Research, 166, Article 115048. https://doi.org/10.1016/j.watres.2019.115048
Zingel, P., Cremona, F., Noges, T., Cao, Y., Neif, E. M., Coppens, J., Iskin, U., Lauridsen, T. L., Davidson, T. A., Sondergaard, M., Beklioglu, M. & Jeppesen, E. (2018). Effects of warming and nutrients on the microbial food web in shallow lake mesocosms. European Journal of Protistology, 64, 1-12. https://doi.org/10.1016/j.ejop.2018.03.001
Zhou, Y., Davidson, T. A., Yao, X., Zhang, Y., Jeppesen, E., Garcia de Souza, J., Wu, H., Shi, K. & Qin, B. (2018). How autochthonous dissolved organic matter responds to eutrophication and climate warming: Evidence from a cross-continental data analysis and experiments. Earth-Science Reviews, 185, 928-937. https://doi.org/10.1016/j.earscirev.2018.08.013
Davidson, T. A., Audet, J., Jeppesen, E., Landkildehus, F., Lauridsen, T. L., Søndergaard, M. & Syväranta, J. (2018). Synergy between nutrients and warming enhances methane ebullition from experimental lakes. Nature Climate Change, 8(2), 156-160. https://doi.org/10.1038/s41558-017-0063-z
Olsen, S., Cao, Y., Florencia Gutierrez, M., Brucet Balmana, S., Landkildehus, F., Lauridsen, T. L., Davidson, T. A., Søndergaard, M., Jeppesen, E. & Risgaard-Petersen, N. (2017). Effect of a nitrogen pulse on ecosystem N processing at different temperatures: A mesocosm experiment with 15NO3 − addition. Freshwater Biology Online, 62(7), 1232-1243. https://doi.org/10.1111/fwb.12940
Audet, J., Machado, É. M. N., Cao, Y., Hoffmann, C. C., Lauridsen, T. L., Larsen, S. E., Sondergaard, M., Jeppesen, E. & Davidson, T. A. (2017). Heat-wave effects on greenhouse gas emissions from shallow lake mesocosms. Freshwater Biology Online, 62(7), 1130-1142. https://doi.org/10.1111/fwb.12930
Cao, Y., Olsen, S., Gutierrez, M. F., Brucet Balmana, S., Davidson, T. A., Li, W., Lauridsen, T. L., Søndergaard, M. & Jeppesen, E. (2017). Temperature effects on periphyton, epiphyton and epipelon under a nitrogen pulse in low-nutrient experimental freshwater lakes. Hydrobiologia, 795(0), 267-279. https://doi.org/10.1007/s10750-017-3140-4
Davidson, T. A., Audet, J., Svenning, J.-C., Lauridsen, T. L., Søndergaard, M., Landkildehus, F., Larsen, S. E. & Jeppesen, E. (2015). Eutrophication effects on greenhouse gas fluxes from shallow lake mesocosms override those of climate warming. Global Change Biology, 21(12), 4449–4463. https://doi.org/10.1111/gcb.13062
Yu, C., Machado, É. M. N., Li, W., Coppens, J., Filiz, N., Lauridsen, T. L., Davidson, T. A., Søndergaard, M. & Jeppesen, E. (2015). Heat wave effects on biomass and vegetative growth of macrophytes after long-term adaptation to different temperatures: a mesocosm study. Climate Research, 66, 265-274. https://doi.org/10.3354/cr01352
Sorf, M., Davidson, T. A., Brucet Balmana, S., Menezes, R., Søndergaard, M., Lauridsen, T. L., Landkildehus, F., Liboriussen, L. & Jeppesen, E. (2015). Zooplankton response to climate warming: a mesocosm experiment at contrasting temperatures and nutrient levels. Hydrobiologia, 742 (1), 185-203. https://doi.org/10.1007/s10750-014-1985-3

Contact

Thomas Alexander Davidson

Professor
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P +4587158743
P +4528323301

Eti Ester Levi

Member of Administrative Staff
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Can small lakes be a big problem?

Shallow lakes and wetlands may in the future play a much more negative role for the climate than their size would suggest.

Greenhouse gases dynamics in shallow lakes: patterns and processes from cells to ecosystems (GreenLakes)

  • Independent Research Fund Denmark | Natural Sciences

The experiments have included:

  • In 2012, experiments were undertaken with a simulation of changed dissolved carbon supply.
  • In 2013, effects of climate on the nitrogen turnover were investigated using marked nitrogen.
  • In 2014, as part of the EU research project MARS, investigations elucidated the long-term effects of an extreme heatwave.
  • In 2018, the effects of reduced nitrogen input were investigated.
  • In 2021, as part of the PONDERFUL project, the effects of temporary stratification were investigated
  • In 2023, the long-term nutrient loading treatments were reversed to track the effects of eutrophication and oligotrophication at different temperatures.

To isolate against both high summer temperatures and frost the experimental tanks and the inlet water supply are dug approx. 1 m into the ground. Temperature sensors, oxygen and pH probes record the physical conditions in the tanks. Photo: Lone Liboriussen ©

Revised 26.02.2026
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Else Vihlborg Staalsen