Longterm P erformance Consequences of Predator Presence in Young-of-the-Year Arctic char.

1. Longterm Performance Consequences of Predator Presence in Young-of-the-Year Arctic char. FJÄLLMistra Jens Andersson Dept. of Ecology and Environmetal Science Umeå University

2. Resource polymorphism is common trait in Arctic char

3. Results from a previous experiment • Different diets gave rise to 2 morphotypes, henceforth benthivoresand planktivores.

4. Results from a previous experiment • Different diets gave rise to 2 morphotypes, henceforth benthivoresand planktivores. • Planktivores had a higher swimming speed when foraging on either prey compared to the benthivores.

5. Results from a previous experiment • Different diets gave rise to 2 morphotypes, henceforth benthivoresand planktivores. • Planktivores had a higher swimmingspeed when foraging on either prey compared to the benthivores. • Planktivores had a higher consumption rate on zooplankton compared to benthivores.

6. Results from a previous experiment • Different diets gave rise to 2 morphotypes, henceforth benthivoresand planktivores. • Planktivores had a higher swimmingspeed when foraging on either prey compared to the benthivores. • Planktivores had a higher consumption rate on zooplankton compared to benthivores. • There were no differences between morphotypes with respect to consumption rate on chironomides.

7. The previous experiment asks the question: • What is the price of including zooplankton in the diet since they • do not loose any competitive ability on chironomids?

8. The previous experiment asks the question: • What is the price of including zooplankton in the diet since they • do not loose any competitive ability on chironomids? The answer? • Planktivory includes a higher level of activity which has been • shown to increase the predation risk and hence foraging on • zooplankton could increase the predation risk

9. The aim of the new experiment • To investigate if the presence of a predator have an effect on morphology, behavior and performance.

10. The aim of the new experiment • To investigate if the presence of a predator have an effect on morphology, behavior and performance. • And if so, do this effect match the results of diet induced differences from the previous experiment.

11. Methods (treatment) • 400 YOY individuals were placed in four 500 L aquarium. (100 ind. in each aquaria).

12. Methods (treatment) • 400 YOY individuals were placed in four 500 L aquarium. (100 ind. in each aquaria). • Plastic tubes were placed at the bottom to immitate natural substrate (shelter).

13. Methods (treatment) • 400 YOY individuals were placed in four 500 L aquarium. (100 ind. in each aquaria). • Plastic tubes were placed at the bottom to immitate natural substrate (shelter). • A net (1 cm meshsize) were placed horizontally, 15 cm above bottom allowing YOY char to pass through.

14. Methods (treatment) • 400 YOY individuals were placed in four 500 L aquarium. (100 ind. in each aquaria). • Plastic tubes were placed at the bottom to immitate natural substrate (shelter). • A net (1 cm meshsize) were placed horizontally, 15 cm above bottom allowing YOY char to pass through. • A large char (25 cm) were placed into two out of four aquarias.

15. Methods (treatment) • 400 YOY individuals were placed in four 500 L aquarium. (100 ind. in each aquaria). • Plastic tubes were placed at the bottom to immitate natural substrate (shelter). • A net (1 cm meshsize) were placed horizontally, 15 cm above bottom allowing YOY char to pass through. • A large char (25 cm) were placed into two out of four aquarias. • All YOY char were fed frozen copepods from above.

16. Methods (measurement) • Attack rate and swimming speed when foraging on each prey type in absence of predator and competitors.

17. Methods (measurement) • Attack rate and swimming speed when foraging on each prey type in absence of predator and competitors. • Morphology by using geometric morhometrics.

18. Result from predator induced YOY-types P NP YOY from non-predator treatment always swim faster independent of prey Swimming speed during foraging Result from diet induced YOY-types Pl B Planktivores always swim faster independent of prey

19. Result from predator induced YOY-types YOY from non-predator treatments () have higher capture rates on zooplankton Average capture rates on zooplankton Result from diet induced YOY-types Planktivores () have higher capture rates on zooplankton

20. Result from diet induced YOY-types Result from predator induced YOY-types There is no difference in capture rates on Chironomides between treatments There is no difference in capture rates on Chironomides between treatments Average capture rates on Chironomids

21. Morphology • We could not find any morphological differences between fry reared in the presence of predators compared to fry reared in the absence of predators (POWER = 0.78).

22. Conclusions • The presence of predators can induce long term effects on the YOY char performance and behaviour.

23. Conclusions • The presence of predators can induce long term effects on the YOY char performance and behaviour. • The changes of performance and behaviour due to presence of predators compared to non-presence of predators are similar to the changes due to growth on a plankton diet compared to growth on a chironomid diet.

24. Conclusions • The presence of predators can induce long term effects on the YOY char performance and behaviour. • The changes of performance and behaviour due to presence of predators compared to non-presence of predators are similar to the changes due to growth on a plankton diet compared to growth on a chironomid diet. • Hence, a combination of diet induced phenotypic plasticity and predation risk may be the cause of different morphotypes of Arctic char often find in one lake.

25. Speculations In char, predation risk may be a driving force for resource polymorphism.

26. The End