Biological Invasions

, Volume 15, Issue 11, pp 2563–2576 | Cite as

Impacts of the invasive alga Sargassum muticum on ecosystem functioning and food web structure

  • Tânia Salvaterra
  • Dannielle S. Green
  • Tasman P. Crowe
  • Eoin J. O’Gorman
Original Paper


Biological invasions have the potential to cause severe alterations to the biodiversity of natural ecosystems. At the same time, variation in the diversity and composition of native communities may have an important influence on the impact of invasions. Here, effects of the invasive Japanese wireweed, Sargassum muticum, were tested across a range of native marine algal assemblages using a combined additive and substitutive design. The invasive alga significantly reduced primary production, an important component of ecosystem functioning, and increased connectance, a key property of the food webs associated with the algal resources. These impacts were mediated by changes in the proportions of intermediate and top species, as well as apparent reductions in faunal species richness and diversity. Some key alterations to faunal species composition (including the arrival of generalist species associated with S. muticum) may have been important in determining these patterns. Overall results suggest that S. muticum not only directly impeded the native algal community, but that these effects extended indirectly to the native fauna and therefore caused major changes throughout the ecosystem.


Invasive species Bottom-up control Macroalgal communities Generalist Robustness Stability Ecosystem process rates Ecological networks 



We would like to thank Judith Kochmann, Emmi Virkki and Jen Coughlan from the GROG group and MarBEE lab at University College Dublin, for assistance with field and laboratory work. We also thank Marina Cunha, Clara Rodrigues and Guy Woodward for valuable comments on the manuscript. TS was supported by an Erasmus training program scholarship. DG was funded by the project SIMBIOSYS (2007-B-CD-1-S1) as part of the Science, Technology, Research and Innovation for the Environment (STRIVE) Programme, financed by the Irish Government under the National Development Plan 2007–2013, administered on behalf of the Department of the Environment, Heritage and Local Government by the Irish Environmental Protection Agency (EPA). EOG is a Postdoctoral Research Fellow funded by NERC (Grant NE/I009280/1) and was supported by the Irish Research Council for Science Engineering and Technology’s EMPOWER initiative during part of this study.

Supplementary material

10530_2013_473_MOESM1_ESM.doc (154 kb)
Supplementary material 1 (DOC 153 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Tânia Salvaterra
    • 1
    • 2
  • Dannielle S. Green
    • 1
  • Tasman P. Crowe
    • 1
  • Eoin J. O’Gorman
    • 1
    • 3
    • 4
  1. 1.School of Biology and Environmental ScienceScience Centre West, University College DublinDublin 4Ireland
  2. 2.Department of BiologyUniversity of Aveiro, Campus Universitário de SantiagoAveiroPortugal
  3. 3.School of Biological and Chemical SciencesQueen Mary University of LondonLondonUK
  4. 4.Imperial College LondonAscot, BerkshireUK

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