The effects of ocean acidification (OA) on the structure and complexity of coastal marine biogenic habitat have been broadly overlooked. Here we explore how declining pH and carbonate saturation may affect the structural complexity of four major biogenic habitats. Our analyses predict that indirect effects driven by OA on habitat-forming organisms could lead to lower species diversity in coral reefs, mussel beds and some macroalgal habitats, but increases in seagrass and other macroalgal habitats. Available in situ data support the prediction of decreased biodiversity in coral reefs, but not the prediction of seagrass bed gains. Thus, OA-driven habitat loss may exacerbate the direct negative effects of OA on coastal biodiversity; however, we lack evidence of the predicted biodiversity increase in systems where habitat-forming species could benefit from acidification. Overall, a combination of direct effects and community-mediated indirect effects will drive changes in the extent and structural complexity of biogenic habitat, which will have important ecosystem effects.

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This article emerged from a working group funded by the Peter Wall Institute for Advanced Studies. We are grateful to R. Bechmann for helpful discussions, and thank the US National Science Foundation, the National Science and Engineering Research Council of Canada, and several of our institutions for research support.

Author information


  1. Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada

    • Jennifer M. Sunday
    • , Kathryn M. Anderson
    • , Norah E. Brown
    • , Megan L. H. Vaughan
    •  & Christopher D. G. Harley
  2. Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia

    • Katharina E. Fabricius
  3. Department of Ecology and Evolutionary Biology, University of California Santa Cruz, California 95064, USA

    • Kristy J. Kroeker
  4. Monterey Bay Aquarium Research Institute, Moss Landing, California 95039, USA

    • James P. Barry
  5. Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, and Environment Institute, University of Adelaide, South Australia 5005, Australia

    • Sean D. Connell
  6. Department of Biological and Environmental Sciences, University of Gothenburg, The Sven Lovén Centre for Marine Sciences, 45178 Fiskebäckskil, Sweden

    • Sam Dupont
  7. Bodega Marine Laboratory and Department of Evolution and Ecology, University of California at Davis, Bodega Bay, California 94923, USA

    • Brian Gaylord
    •  & Eric Sanford
  8. Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, Plymouth University, Plymouth PL4 8AA, UK

    • Jason M. Hall-Spencer
  9. Shimoda Marine Research Centre, Tsukuba University, Shimoda City, Shizuoka 415-0025, Japan

    • Jason M. Hall-Spencer
  10. School of Marine and Environmental Affairs, University of Washington, Seattle, Washington 98105, USA

    • Terrie Klinger
  11. Dipartimento di Scienze della Terra e del Mare, University of Palermo, CoNSIMa Consortium, Palermo I-90123, Italy

    • Marco Milazzo
  12. ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia

    • Philip L. Munday
  13. The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Hong Kong SAR

    • Bayden D. Russell
    •  & Vengatesen Thiyagarajan
  14. Plymouth Marine Laboratory, Plymouth PL1 3DH, UK

    • Stephen Widdicombe


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All authors conceptualized and designed the paper; J.M.S., K.E.F., K.J.K., K.M.A., N.E.B., J.M.H.-S., M.M. and C.D.G.H. assembled the data; J.M.S. analysed the data, produced figures and drafted the paper; all authors contributed discussion, writing and interpretation.

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The authors declare no competing financial interests.

Corresponding author

Correspondence to Jennifer M. Sunday.

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