TY - JOUR

T1 - Patterns in reef fish assesmblages

T2 - insights from the Chagos Archipelago

AU - Samoilys, Melita

AU - Roche, Ronan

AU - Koldewey, Heather

AU - Turner, John

PY - 2018/1/19

Y1 - 2018/1/19

N2 - Understanding the drivers of variability in the composition of fish assemblages acrossthe Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilstnumerous relationships and feedback mechanisms between the functional roles ofcoral reef fishes and reef benthic composition have been investigated, certain keygroups, such as the herbivores, are widely suggested to maintain reefs in a coraldominatedstate. Examining links between fishes and reef benthos is complicated bythe interactions between natural processes, disturbance events and anthropogenicimpacts, particularly fishing pressure. This study examined fish assemblages andassociated benthic variables across five atolls within the Chagos Archipelago, wherefishing pressure is largely absent, to better understand these relationships. We foundhigh variability in fish assemblages among atolls and sites across the archipelago,especially for key groups such as a suite of grazer-detritivore surgeonfish, and theparrotfishes which varied in density over 40-fold between sites. Differences in fishassemblages were significantly associated with variable levels of both live and recentlydead coral cover and rugosity. We suggest these results reflect differing coral recoverytrajectories following coral bleaching events and a strong influence of 'bottom-up'control mechanisms on fish assemblages. Species level analyses revealed that Scarusniger, Acanthurus nigrofuscus and Chlororus strongylocephalos were key speciesdriving differences in fish assemblage structure. Clarifying the trophic roles ofherbivorous and detritivorous reef fishes will require species-level studies, which alsoexamine feeding behaviour, to fully understand their contribution in maintaining reefresilience to climate change and fishing impacts.

AB - Understanding the drivers of variability in the composition of fish assemblages acrossthe Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilstnumerous relationships and feedback mechanisms between the functional roles ofcoral reef fishes and reef benthic composition have been investigated, certain keygroups, such as the herbivores, are widely suggested to maintain reefs in a coraldominatedstate. Examining links between fishes and reef benthos is complicated bythe interactions between natural processes, disturbance events and anthropogenicimpacts, particularly fishing pressure. This study examined fish assemblages andassociated benthic variables across five atolls within the Chagos Archipelago, wherefishing pressure is largely absent, to better understand these relationships. We foundhigh variability in fish assemblages among atolls and sites across the archipelago,especially for key groups such as a suite of grazer-detritivore surgeonfish, and theparrotfishes which varied in density over 40-fold between sites. Differences in fishassemblages were significantly associated with variable levels of both live and recentlydead coral cover and rugosity. We suggest these results reflect differing coral recoverytrajectories following coral bleaching events and a strong influence of 'bottom-up'control mechanisms on fish assemblages. Species level analyses revealed that Scarusniger, Acanthurus nigrofuscus and Chlororus strongylocephalos were key speciesdriving differences in fish assemblage structure. Clarifying the trophic roles ofherbivorous and detritivorous reef fishes will require species-level studies, which alsoexamine feeding behaviour, to fully understand their contribution in maintaining reefresilience to climate change and fishing impacts.

KW - coral reef; reef fish; reef benthic composition; fish functional groups

U2 - 10.1371/journal.pone.0191448

DO - 10.1371/journal.pone.0191448

M3 - Article

VL - 13

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 1

M1 - e0191448

ER -