Research interests

My research focus on the ecology of pelagic food webs (including zooplankton, phytoplankton, bacterioplankton and fish) in freshwater ecosystems. The research cover a range in scale from individual organisms to ecosystems and has to a large extent been carried out within the theoretical framework of ecological stoichiometry. The approaches have mainly been experimental, using experimental systems ranging in size from laboratory microcosms to whole lake experiments, and regional surveys. Both basic and applied research topics are addressed, for example:  

• Regulation of phytoplankton and bacterioplankton growth by nutrients (phosphorus, nitrogen, iron, and organic matter).
• Ecological stoichiometry of zooplankton in connection to organismal ecophysiology.
• Food quality limitation of zooplankton growth (elemental stoichiometry and essential fatty acids) 
• Essential fatty acids in freshwater ecosystems.
• Energy mobilisation and trophic transfer of energy and matter in pelagic food webs. 
• Ecological effects of hydroelectric power reservoirs and mitigation of oligotrophication by compensatory nutrient enrichment.

Environmental monitoring and assessment

• Scientific project leader for Integrated studies of the effects of liming acidified waters.
• Involved in assessment programs in e.g. the Eskilstunaån and Arbogaån catchments 

Teaching

I'm currently involved in teaching on the course Aquatic environmental assessment.

PhD student supervision (active students)

• Karin Johansson (2011-) Effects of the bloom-forming mixotrophic flagellate Gonyostomum semen on the biodiversity and food web structure of dystrophic lakes (co-supervisor, SLU).
• Anja Wenzel (2008-) Transfer of carbon and nutrients from energy mobilizers to metazoan zooplankton: Dependence on food web structure and C:nutrient stoichiometry (co-supervisor, Umeå University). 

PhD student supervision (finished students)

• Jonas Persson (2001-2007) Food quality effects on zooplankton growth and energy transfer in pelagic freshwater food webs (main supervisor, Uppsala University).
• Carolyn Faithfull (2006-2011) Productivity and carbon transfer in pelagic food webs (co-supervisor, Umeå University).
• Antonia Liess (2004-2006) Nutrient stoichiometry in benthic food webs - interactions between algae, herbivores and fish (co-supervisor, Uppsala University).

Appointments

• Joint chief editor of Fundamental and Applied Limnology

Selected publications

Lau D.C.P., Vrede T., Pickova J. & Goedkoop W. (2012). Fatty acid composition of consumers in boreal lakes - variation across species, space and time. Freshwat. Biol., 57, 24-38.

Wenzel A., Bergström A.-K., Jansson M. & Vrede T. (2012). Survival, growth and reproduction of Daphnia galeata feeding on single and mixed Pseudomonas and Rhodomonas diets. Freshwat. Biol., 57, 835-846.

Faithfull C.L., Bergström A.-K. & Vrede T. (2011). Effects of nutrients and physical lake characteristics on bacterial and phytoplankton production: A meta-analysis. Limnol. Oceanogr., 56, 1703-1713.

Faithfull C.L., Huss M., Vrede T. & Bergström A.-K. (2011). Bottom-up carbon subsidies and top-down predation pressure interact to affect aquatic food web structure. Oikos, 120, 311-320.

Milbrink G., Vrede T., Tranvik L.J. & Rydin E. (2011). Large scale and long-term decrease in fish growth following the construction of hydroelectric reservoirs. Can. J. Fish. Aquat. Sci., 68, 2167-2173.

Vrede T., Drakare S., Eklöv P., Hein A., Liess A., Olsson J., Persson J., Quevedo M., Ragnarsson H. & Svanbck R. (2011). Ecological stoichiometry of Eurasian perch effects of size, habitat and diet. Oikos, 120, 886-896.

Vrede T., Ballantyne A.P., Mille-Lindblom C., Algesten G., Gudasz C., Lindahl S. & Brunberg A.K. (2009). Effects of N:P loading ratios on phytoplankton community composition, primary production, and N fixation in a eutrophic lake. Freshwat. Biol., 54, 331-344.

Persson J. & Vrede T. (2006). Polyunsaturated fatty acids in zooplankton: variation due to taxonomy and trophic position. Freshwat. Biol., 51, 887-900.

Vrede T. & Tranvik L.J. (2006). Iron constraints on planktonic primary production in oligotrophic lakes. Ecosystems, 9, 1094-1105.

Vrede T., Dobberfuhl D.R., Kooijman S.A.L.M. & Elser J.J. (2004). Fundamental connections among organism C:N:P stoichiometry, macromolecular composition, and growth. Ecology, 85, 1217-1229.

Vrede T., Andersen T. & Hessen D.O. (1999). Phosphorus distribution in three crustacean zooplankton species. Limnol. Oceanogr., 44, 225-229.

Sundbom M. & Vrede T. (1997). Effects of fatty acid and phosphorus content of food on the growth, survival and reproduction of Daphnia. Freshwat. Biol., 38, 665-674.