1 Ocean acidification can mediate biodiversity shifts by changing biogenic habitat Jennifer M. Sunday* 1 , Katharina E. Fabricius 2 , Kristy J. Kroeker 3 , Kathryn M. Anderson 1 , Norah E. Brown 1 , James P. Barry 4 , Sean D. Connell 5 , Sam Dupont 6 , Brian Gaylord 7 , Jason M. Hall- Spencer 8,9 , Terrie Klinger 10 , Marco Milazzo 11 , Philip L. Munday 12 , Bayden D. Russell 13 , Eric Sanford 7 , Vengatesen Thiyagarajan 13 , Megan L.H. Vaughan 1 , Steven Widdicombe 14 , and Christopher D. G. Harley 1 1 Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T174 Canada 2 Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia 3 Department of Ecology and Evolutionary Biology, University of California Santa Cruz, California 95064 USA 4 Monterey Bay Aquarium Research Institute, Moss Landing, California 95039 USA 5 Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, and Environment Institute, University of Adelaide, South Australia 5005, Australia 6 Department of Biological and Environmental Sciences, University of Gothenburg, The Sven Lovén Centre for Marine Sciences, 45178 Fiskebäckskil, Sweden 7 Bodega Marine Laboratory and Department of Evolution and Ecology, University of California at Davis, Bodega Bay, California 94923 USA 8 Marine Biology and ecology research Centre, School of Marine Science and Engineering, Plymouth University, United Kingdom 9 Shimoda Marine Research Centre, Tsukuba University, Japan 10 School of Marine and Environmental Affairs, University of Washington, Seattle, Washington 98105 USA 11 Dipartimento di Scienze della Terra e del Mare, University of Palermo, Palermo, Italy