Habitat associations of juvenile versus adult butterflyfishes

Abstract

Many coral reef fishes exhibit distinct ontogenetic shifts in habitat use while some species settle directly in adult habitats, but there is not any general explanation to account for these differences in settlement strategies among coral reef fishes. This study compared distribution patterns and habitat associations of juvenile (young of the year) butterflyfishes to those of adult conspecifics. Three species, Chaetodon auriga, Chaetodon melannotus, and Chaetodon vagabundus, all of which have limited reliance on coral for food, exhibited marked differences in habitat association of juvenile versus adult individuals. Juveniles of these species were consistently found in shallow-water habitats, whereas adult conspecifics were widely distributed throughout a range of habitats. Juveniles of seven other species (Chaetodon aureofasciatus, Chaetodon baronessa, Chaetodon citrinellus, Chaetodon lunulatus, Chaetodon plebeius, Chaetodon rainfordi, and Chaetodon trifascialis), all of which feed predominantly on live corals, settled directly into habitat occupied by adult conspecifics. Butterflyfishes with strong reliance on corals appear to be constrained to settle in habitats that provide access to essential prey resources, precluding their use of distinct juvenile habitats. More generalist butterflyfishes, however, appear to utilise distinct juvenile habitats and exhibit marked differences in the distribution of juveniles versus adults.