The effects of coral bleaching on settlement preferences and growth of juvenile butterflyfishes

• We examined settlement preferences and subsequent growth of butterflyfishes in bleached versus healthy corals.
• Juvenile coral-feeding fishes are generally insensitive to short term effects of bleaching.
• Coral-feeding butterflyfishes readily settle in bleached corals.
• Juvenile butterflyfishes readily consume bleached corals and exhibit similar growth to fishes on healthy corals.
• Short-term and moderate bleaching has limited effects on butterflyfishes, but fishes will be affected if host corals die.

Coral bleaching and associated mortality is an increasingly prominent threat to coral reef ecosystems. Although the effects of bleaching-induced coral mortality on reef fishes have been well demonstrated, corals can remain bleached for several weeks prior to recovery or death and little is known about how bleaching affects resident fishes during this time period. This study compared growth rates of two species of juvenile butterflyfishes (Chaetodon aureofasciatus and Chaetodon lunulatus) that were restricted to feeding upon either bleached or healthy coral tissue of Acropora spathulata or Pocillopora damicornis. Coral condition (bleached vs. unbleached) had no significant effects on changes in total length or weight over a 23-day period. Likewise, in a habitat choice experiment, juvenile butterflyfishes did not discriminate between healthy and bleached corals, but actively avoided using recently dead colonies. These results indicate that juvenile coral-feeding fishes are relatively robust to short term effects of bleaching events, provided that the corals do recover.