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Christer Brönmark

Professor | PhD

Is predation an important selection force in freshwater systems? This question has been a consistent theme in almost all the different projects I have been involved in, throughout my career. My research has involved many different organisms, from snails to piscivorous fish, and I have been working with interactions at different organisational levels, from individual behaviour to the structure and function of ecosystems. At present, I am involved in three different projects where I study the effects of predator-prey interactions on:

Evolution of inducible defenses

Schematic image of carp experiment.

Virtually all animals constitute potential prey and they are hence under strong selection to avoid capture by their natural enemies. Consequently, we see a huge range of fantastic anti-predator defences displayed in prey organisms. Defences could either be constitutive, i.e. they are always expressed by the prey, regardless of predation risk. Or they could be inducible, i.e. they are only expressed in the presence of predators. We have for a number of years studied the costs and benefits of inducible morphological defences in freshwater prey species. The fascinating crucian carp, Carassius carassius, reacts to chemical cues emitted by predatory fish by growing a deeper bodied morphology. The deeper body provides a benefit by reducing vulnerability to predation, but also incur a cost by increasing drag when swimming. We have also shown inducible defence adaptations in the snail Radix balthica – it grows a more rotund shell when exposed to fish cues, a morphology that increase resistance to crushing.

In recent years we have seen considerable development of the theoretical underpinnings as well as empirical studies on the evolution of phenotypically plastic defences, but we still need to identify the proximate, physiological mechanisms behind the expression of defence traits in order to advance our understanding. Further, it is pivotal to study the expression of these adaptations in a multiple trait context, especially with regards to animal personality, and in environments that differ in selection regimes. In our present research we use the unique crucian carp model system to challenge fundamental and exciting research questions, including the proximate, physiological mechanisms behind inducible defences (especially the stress axis and the importance of cortisol), how multiple defence traits combine to produce an adaptive, integrated phenotype and how environmental heterogeneity drives plasticity vs. canalisation of defence traits.

Selected Publications

  • Brönmark, C. and Miner, J.G. 1992. Predator-induced phenotypical change in body morphology in crucian carp. Science 258: 1348-1350.
  • Hulthén, K., Chapman, B. B., Nilsson, P. A., Hollander, J. and Brönmark, C. 2014. Express yourself: bold individuals enhance morphological defences. Proc. R. Soc. Lond. Ser. B 281: 20132703.

Seasonal migration in freshwater fishes

migrating roach
Photo: Aron Hejdström

In this project we study the causes and consequences of seasonal migration in a freshwater cyprinid fish, the roach Rutilus rutilus, in lakes in Sweden and Denmark. In the autumn, roach migrate from the lake into streams and wetlands and then return to the lake in early spring. We have shown that this migration is driven by a seasonal change in a cost/benefit trade-off, where the predation costs and growth benefits change seasonally in the lake and stream habitats. The migration is partial and individual properties such as size, condition and personality affects an individual’s migratory drive. Differences in the density and biomass of migratory roach among years may further have repercussions on the dynamics of the whole ecosystem, specifically by affecting the zooplankton dynamics during spring. At present, we are investigating how differences in immune defence affect migratory propensity and overwinter survival.

Selected publications

  • Brönmark, C, Skov, C, Brodersen, J, Nilsson, P A and Hansson, L-A 2008. Seasonal migration determined by a trade-off between predator avoidance and growth PloS One 3(4): e1957
  • Chapman, B., Hulthén, K., Blomqvist, D., Hansson, L-A., Nilsson, J-Å, Brodersen, J., Nilsson, P. A. Skov, C. and Brönmark, C. 2011. To boldly go: Individual differences in boldness influence migratory tendency. Ecology Letters 14: 871-876.

Environmental effects on piscivore recriutment

Predation by fish is one of the most important structuring forces in lake ecosystems and it has been repeatedly shown that changes in the density and species composition of the piscivore functional group have complex effects on freshwater food chains, thereby affecting the dynamics and function of the whole system. In earlier studies we have shown that changes in the optical environment (light availability) due to increased turbidity or increased humic content (brownification) have a negative effect on foraging and growth rate of adult piscivorous fish. The aim of this project is to study how environmental drivers (temperature and eutrophication) associated with climate change will affect the recruitment success of two of our most important freshwater piscivorous fish, pike and pikeperch, due to singular and synergistic effects on the larval and juvenile life history stages. A temperature increase is predicted to affect growth rate by both a change in foraging rate and through changes in food availability (mismatch of resources), whereas eutrophication will affect prey encounter rates through detoriation of the optical properties of water.

Selected publications

  • Ranåker, L., Jönsson, M., Nilsson, P. A. and Brönmark, C. 2012. Effects of brown and turbid water on piscivore-prey fish interactions along a visibility gradient Freshwater Biol 57: 1761-1768.
  • Jönsson, M., Ranåker, L. Nilsson, P.A. and Brönmark, C. 2013. Foraging efficiency and prey selectivity in a visual predator: differential effects of turbid and humic water. Can. J. Fish. Aquat. Sci. 70: 1685-1690

Publications

Retrieved from Lund University's publications database

Page Manager:
Christer Brönmark
E-mail: christer.bronmark [at] biol.lu.se

Head of unit

Aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Professor

Aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Research group

Aquatic Ecology

Projects

Doctoral students and postdocs

PhD students, main supervisor

Jerker Vinterstare

PhD students, assistant supervisor

Yongcui Sha

Downloads & links

Centre for Animal Movement Research (CAnMove)

My ResearchGate page

Slim and fat fsh