Low feeding preference of native herbivores for the successful non-native seaweed Heterosiphonia japonica
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Non-native seaweeds constitute a conspicuous component of many benthic coastal communities. Seaweed invaders are known to significantly affect invaded communities, but relatively little is known about the mechanisms underlying their success. In this study, we explored the feeding preferences of three generalist herbivores for the successful non-native red alga Heterosiphonia japonica and native seaweed competitors. The experiments were conducted on the Swedish Skagerrak coast (58°52′N, 11°08′E) from July to August. Additionally, chemical and physical traits of the seaweeds were assessed to mechanistically explain herbivore preferences. The results showed that H. japonica was of low preference to native herbivores and that this was most likely explained by chemical properties of the invader. We were, however, not able to determine whether the low preference was caused by deterrent metabolites or low nutritional quality. We conclude that herbivore avoidance may be important for the survival and success of H. japonica in the introduced range and that efficient means of escaping herbivory may be a common feature of invaders in seaweed communities.
KeywordsInvasion Success Generalist Herbivore Native Herbivore Ectocarpus Siliculosus Native Seaweed
We thank G. Cervin, G. M. Nylund, E. Bergvall and F. Baumgartner for field assistance. We also want to thank the staff at the Tjärnö Laboratory (Sven Lovén Centre for Marine Sciences) for their hospitality and practical assistance. We thank F. Baumgartner and two anonymous reviewers for helpful comments that helped improve the manuscript. The work was supported by grants from the Royal Swedish Academy of Sciences (to J. S.) and the Swedish Research Council Formas through contract no. 217-2007-534 (to S. A. W.) and by the Swedish Research Council VR through contract no. 621-2011-5630 (to H. P.).
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