Assemblage structure of butterflyfishes and their use as indicators of Gulf of Aqaba benthic habitat in Jordan

Abstract

1. A spatially comprehensive description of the butterflyfish assemblage structure is presented, as well as an examination of the relationship of butterflyfish with the dominant living substrate distribution of seagrass and living coral complex (combination of soft and hard corals). The utility of using abundance of particular butterflyfish species as indicators for abundance and change in coral reefs of the northern Gulf of Aqaba is also discussed. 2. The most common species of butterflyfish along the Jordanian coast of the Gulf of Aqaba was Chaetodon paucifasciatus, while the most infrequently observed was Chaetodon trifascialis. 3. The only site along the entire coast of Jordan that had a majority (55.5%) of its benthic environment covered with living coral complex was the Jordan–Saudi Arabia border. The only other site that had a majority of its benthic environment covered with a living substrate was Al-Mamlah which had 70.7% seagrass cover. All other sites had the majority of their substrate composed of dead coral/rubble/sand complex. 4. Nine sites had dominant living substrate, both by depth and with all depths within a site combined, composed of coral complex, while the remaining four were composed of seagrass. 5. Butterflyfish species richness at coral complex sites was significantly greater than for seagrass sites. 6. Abundance of Chaetodon austriacus is the single best indicator species for proportion of benthic habitat covered by coral complex. C. austriacus, C. paucifasciatus and Chaetodon melannotus combined explain the majority of variability in percentage coral complex coverage. 7. Abundance of C. paucifasciatus is the single best indicator species for proportion of benthic habitat covered by hard coral, and, when combined with C. austriacus, explains the majority of variability in percentage hard coral coverage. 8. Abundance of C. austriacus is the single best indicator of soft coral coverage. However, even when combined with other butterflyfish species, not more than approximately 20% of the variability in percentage soft coral coverage can be explained by butterflyfish abundance. 9. Neither abundance of C. trifascialis nor total butterflyfish abundance are recommended as viable indicators for coral complex, hard or soft coral cover in the northern Gulf of Aqaba. 10. Results support the butterflyfish indicator species concept that specific coral-feeding butterflyfish species, and not total butterflyfish abundance, may be a valuable indicator of changes to coral reef ecosystems. However, additional studies are needed to elucidate the behavioural traits (i.e. feeding rates, territory size and agonistic encounters) of the candidate species C. austriacus, C. melannotus and C. paucifasciatus. Such studies should be included as part of implementation of a broader, regional long-term butterflyfish monitoring programme. Copyright © 2005 John Wiley & Sons, Ltd.