Interactions between habitat use and patterns of abundance in coral-dwelling fishes of the genus Gobiodon

Coral-dwelling fishes from the genus Gobiodon are some of the most habitat specialised fishes on coral reefs. Consequently, we might expect that their population dynamics will be closely associated with the abundance of host corals. I used a combination of log-linear modelling and resource selection ratios to examine patterns of habitat use among eight species of Gobiodon in Kimbe Bay, Papua New Guinea. I then used multiple regression analysis to investigate relationships between the abundance of each species of Gobiodo n and the abundance of the corals they inhabited. Each species of Gobiodon used one or more species of coral more frequently than expected by chance. The pattern of habitat use exhibited by each species of Gobiodon did not va ry among reef zones or among reefs with different exposures to prevailing w inds, despite changes in the relative abundances of corals among reef zones . This consistency in habitat use might be expected if the coral species in habited confer considerable fitness advantages and, therefore, are strongly preferred. For most species of Gobiodon, abundances among reef zones and e xposure regimes were correlated with the abundance of the coral species usu ally inhabited. Therefore, it appears that habitat availability helps deter mine abundances of most species of Gobiodon in Kimbe Bay. In addition to co rrelations with habitat availability, the abundances of G. histrio, G. quin questrigatus, G. rivulatus (dark form) and the group 'others' were also ass ociated with particular reef zones and exposure regimes. Therefore, in thes e species, reef type appears to influence patterns of abundance independent ly of coral availability. In contrast to other species of Gobiodon, the abu ndance of the most specialised species, Gobiodon sp.A, was not closely asso ciated with the abundance of the only coral species it inhabited. This stud y demonstrates that even for habitat specialised species, the relationship between habitat availability and abundance varies widely and is multiscale.