OCEANARIUM Obligate corallivorous filefish (Oxymonacanthus longirostris) switches diet from Acropora to Pocillopora corals following habitat loss Jean-Paul A. Hobbs Received: 3 February 2013 / Revised: 2 April 2013 / Accepted: 3 April 2013 / Published online: 24 April 2013 # Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2013 The high diversity of coral reef fishes is threatened by increasing habitat destruction. The greatest impact has been on habitat and dietary specialists, particularly those dependent on Acropora corals (Pratchett et al. 2008). The future of these specialist species will depend on their ability to use alternate resources. One of the most specialized species is the harlequin filefish (Oxymonacanthus longirostris), which feeds almost exclusively on live Acropora corals (Kokita and Nakazono 2001; Brooker et al. 2012). Acropora corals are particularly susceptible to disturbance, and recent mortality on many reefs has resulted in local extinctions of the harlequin file- fish (Kokita and Nakazono 2001). Extensive surveys from 2002 to 2008 confirmed the ex- tinction of the harlequin filefish at Christmas Island (Indian Ocean) following the loss of Acropora corals (Hobbs et al. 2010). However, one individual was recently seen at a mon- itoring site in Flyingfish Cove on December 14, 2011. Most strikingly, this individual was feeding almost entirely on Pocillopora verrucosa (Fig 1, Online Resource 1). During 30 min of observations, the individual took 372 bites from nine different colonies and 12 bites from areas of dead coral. The following day, it took 109 bites from four P. verrucosa colonies and 7 bites of dead coral during 10 min. Before extinction at Christmas Island, harlequin filefish were only seen in stands of branching Acropora. At Flyingfish Cove, Acropora cover has decreased from 18 % in 2005 to 7 % in 2011 (2011 dominated by A. hyacinthus, A. Fig. 1 a Oxymonacanthus longirostris and its typical food source (Acropora corals), and b feeding on Pocillopora verrucosa at Christmas Island Electronic supplementary material The online version of this article (doi:10.1007/s12526-013-0155-6) contains supplementary material, which is available to authorized users. J.-P. A. Hobbs (*) The Oceans Institute and School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA, Australia 6009 e-mail: jean-paul.hobbs@uwa.edu.au Mar Biodiv (2013) 43:175–176 DOI 10.1007/s12526-013-0155-6