Short- and long-term effects of disturbance and propagule pressure on a biological invasion

Authors

  • Kevin H. Britton-Simmons,

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      *Correspondence and present address. Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA. E-mail: aquaman@u.washington.edu
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  • Karen C. Abbott

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    • Present address: Department of Zoology, University of Wisconsin, 430 Lincoln Drive, Madison, WI 53706, USA


*Correspondence and present address. Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA. E-mail: aquaman@u.washington.edu

Summary

  • 1Invading species typically need to overcome multiple limiting factors simultaneously in order to become established, and understanding how such factors interact to regulate the invasion process remains a major challenge in ecology.
  • 2We used the invasion of marine algal communities by the seaweed Sargassum muticum as a study system to experimentally investigate the independent and interactive effects of disturbance and propagule pressure in the short term. Based on our experimental results, we parameterized an integrodifference equation model, which we used to examine how disturbances created by different benthic herbivores influence the longer term invasion success of S. muticum.
  • 3Our experimental results demonstrate that in this system neither disturbance nor propagule input alone was sufficient to maximize invasion success. Rather, the interaction between these processes was critical for understanding how the S. muticum invasion is regulated in the short term.
  • 4The model showed that both the size and spatial arrangement of herbivore disturbances had a major impact on how disturbance facilitated the invasion, by jointly determining how much space-limitation was alleviated and how readily disturbed areas could be reached by dispersing propagules.
  • 5Synthesis. Both the short-term experiment and the long-term model show that S. muticum invasion success is co-regulated by disturbance and propagule pressure. Our results underscore the importance of considering interactive effects when making predictions about invasion success.

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