, Volume 147, Issue 4, pp 692–701 | Cite as

Export of detached macroalgae from reefs to adjacent seagrass beds

  • Thomas WernbergEmail author
  • Mathew A. Vanderklift
  • Jason How
  • Paul S. Lavery
Community Ecology


Trophic linkages across habitats are thought to be strong when areas of different productivity are juxtaposed. Reefs dominated by macroalgae are commonly juxtaposed to less productive seagrass beds. We tested if macroalgae detached from 12 rocky reefs in south-western Australia were exported to adjacent seagrass beds and consumed by seagrass-associated fauna. We also assessed the extent of linkages by testing for patterns in biomass and consumption of reef algae, and density of herbivorous fish with increasing distance away from reefs.

Detached reef algae were found in seagrass beds adjacent to all reefs. The biomass varied among reefs and with distance from reef, but detached reef algae within the seagrass beds comprised up to 23% (mean 3.6% ± 0.7 SE) of attached algae growing on an equivalent area of reef. Maximum accumulations were found immediately adjacent to reefs (0 m) and at the furthest distance away (>300 m). Kelp (Ecklonia radiata) dominated the attached and detached algae, and up to 77% of the biomass of E. radiata tethered in seagrass beds were consumed over 5 days (mean 11.7% ± 0.5 SE). There were more herbivorous fish at 0 m than at >300 m away from reefs, and consumption of tethered kelp was typically highest at 0 m, but was in some cases highest at >300 m.

Our study documents that, over hundreds of kilometres of coastline, macroalgae are exported from reefs to adjacent seagrass beds where they are consumed by seagrass-associated fauna. While reef algae in seagrass beds may be a patchy resource at a single time, at landscape scales and over longer time periods, the supply will be relatively predictable. We therefore suggest that detached reef algae form a significant trophic link between reefs and seagrass beds, and that this trophic link extends to distances of at least hundreds of metres away from individual reefs.


Connectivity Food webs Fish herbivory Habitat linkages Spatial subsidy 



This research was supported by the Australian Research Council, the Department of Environmental Protection (Western Australia) and Edith Cowan University. We thank Lachlan MacArthur, Tim Daly, Cameron Sim, Kirsten Wiseman, Andrew Tennyson and Matt Kletzcowski for assistance in the field. Phillip England provided insightful comments on the manuscript. The work detailed in this paper comply with the laws of Australia.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Thomas Wernberg
    • 1
    Email author
  • Mathew A. Vanderklift
    • 1
    • 2
  • Jason How
    • 1
  • Paul S. Lavery
    • 1
  1. 1.Centre for Ecosystem ManagementEdith Cowan UniversityJoondalupAustralia
  2. 2.CSIRO Marine ResearchWembleyAustralia

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