Herbivory and functional traits suggest that enemy release is not an important mechanism driving invasion success of brown seaweeds

Abigail L. Mabey*, Jane A. Catford, Marc Rius, Andrew Foggo, Dan A. Smale

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Invasive species are a global threat to biodiversity and there is a pressing need to better understand why some species become invasive outside of their native range, and others do not. One explanation for invasive species success is their release from concurrent natural enemies upon introduction to the non-native range. The so-called enemy release hypothesis (ERH) has conflicting support, depending upon the ecosystem and species investigated. To date, most studies testing the generality of the ERH have focused on terrestrial ecosystems. Here, we tested whether enemy release might contribute to the success of the invasive non-native brown seaweeds Undaria pinnatifida and Sargassum muticum in the United Kingdom. We conducted choice and no choice experiments to determine herbivore preference on these invaders relative to six functionally-similar native species. We also measured and compared species traits associated with defence against herbivory (carbon to nitrogen ratio, polyphenolic concentration, tensile strength, and compensatory growth). There were no differences in the biomass consumed between invasive and native species for either choice or no choice tests. The carbon to nitrogen ratio (a measure of nutritional quality) was significantly lower for S. muticum compared to the three native fucoid species, but measures of the other three defence traits were similar or even greater for invasive species compared with native species. Taken together, it is unlikely that the ERH applies to invasive seaweeds in the northeast Atlantic, suggesting that other factors may contribute to the success of invasive species in this system.

Original languageEnglish
Pages (from-to)3919-3934
Number of pages16
JournalBIOLOGICAL INVASIONS
Volume24
Issue number12
DOIs
Publication statusPublished - Dec 2022

Keywords

  • Defence
  • Functional traits
  • Herbivory
  • Macroalgae
  • Non-indigenous species
  • Non-native species

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