1. Enemy release in an invading seaweed
Sofia A. Wikström, María B. Steinarsdottir, Lena Kautsky & Henrik Pavia

2. Enemy release Generalists Native range Specialists Herbivores
New range
Generalists
Specialists
Herbivores ?

3. Aim Evaluate the enemy release hypothesis for an invading seaweed
Fucus evanescens

4. Tjärnö
SW Iceland
1902
1952
1980
1898
1924
1928
1948
1990

5. Tång Field sampling 3 sites in Sweden and 3 in Iceland
Fucus vesiculosus
Ascophyllum nodosum
Fucus evanescens
Tång
Field sampling
3 sites in Sweden and 3 in Iceland
4 plants from each site

6. Herbivore species richness

7. Herbivore abundance

8. Grazing damage

9. Herbivore preference Iceland Sweden Littorina obtusata
Idotea granulosa

10. Conclusions
Fucus evanescens has lower species richness and abundance of herbivores in new but not in native range
Fucus evanescens is less damaged and less preferred in the new range but more damaged and preferred in the native range
Enemy release despite similar community and low specificity?
Importance of resistance to herbivory

11. Phlorotannin content

12. Phlorotannin content

13. Final conclusions
Fucus evanescens is less utilised by herbivores in the new range
Due to local adaptation of herbivores?
Or higher level of defence?
Important to compare defence levels in introduced and native plant populations when assessing enemy release

14. Acknowledgements
Staff at Tjärnö Marine Biological Laboratory and Sandgerði Marine Centre
Financing agencies: Swedish Environmental Protection Agency European Union Icelandic Centre for Research Stockholm Marine Research Centre