Relationships among distribution, abundance and microhabitat specialisation in a guild of coral reef triggerfish (family Balistidae)

Abstract

The potential relationship between ecological versatility and local distribution and abundance for 5 species of triggerfish was examined at Kimbe Bay, Papua New Guinea. The abundances of juvenile and adult Balistapus undulatus, Melichthys vidua, Rhinecanthus verrucosus, Sufflamen bursa and S. chrysopterus were quantified in a range of habitats along a typical coral reef profile. Four of the 5 species displayed distinct and relatively narrow distributions across the reef profile, with the fifth species, B. undulatus, being broadly distributed across all zones and depths, and the most abundant species. For each species, the spatial distribution of juveniles closely matched that of adults and juvenile densities were greater in species with more abundant adults. A detailed description of depth distributions of individuals indicated that shallow species had narrower depth ranges. In terms of microhabitat use, B. undulatus was the most generalised species, occupying all the microhabitats that were identified. The other 4 species were specialised to varying degrees on different microhabitats. Results from this study provide the first detailed description of patterns of distribution and abundance, habitat use and ecological versatility in triggerfish. Distribution and abundance could partially be explained by differences in the degree to which each species is specialised, both in terms of depth and microhabitat selectivity. Hence, versatility in depth and microhabitat use may play an important role in determining the local distribution and relative abundance of coral reef fishes.