Diversity in diet and feeding behaviour of butterflyfishes: reliance on reef corals versus reef habitats

[Extract] Considerable research attention has focused on the feeding habits of coral reef butterflyfishes, especially Chaetodon butterflyfishes (reviewed by Cole et al., 2008), largely due to their propensity to feed on corals (more specifically, reef-building scleractinian corals). Coral feeding infers a very high dependence upon living corals, which has led to suggestions that changes in the-abundance (or behaviour) of butterflyfishes may provide an effective indicator for declines in coral cover (e.g., Khalaf and Crosby, 2005; Gochfeld, 2006), or even declining condition of entire coral reef ecosystems (Reese, 1977; Hourigan et al., 1988; Crosby and Reese, 1996, 2005). Butterflyfishes, especially highly specialised coral-feeding species, are certainly sensitive to changes in the availability of scleractinian corals (e.g., Crosby and Reese, 2005; Samways, 2005; Pratchett et al.,2006; Graham, 2007; Wilson et al., Chapter 14). However, responses of butterflyfishes to coral loss are very complex, highly species-specific, and often delayed, which greatly reduces their effectiveness as indicators of coral health (Crosby et al., Chapter 10). Variation in dietary breadth and composition among butterflyfishes, which determines coral-dependence, is nonetheless very important in understanding inherent vulnerabilities of butterflyfishes to sustained and ongoing coral loss associated with the worldwide degradation of coral reef ecosystems (Pratchett et al., 2008a, Pratchett, Chapter 6)