MEPS 152:227-239 (1997)  -  doi:10.3354/meps152227

Many fishes on coral reefs are known to associate with particular microhabitats. If these associations help determine population dynamics then we would expect (1) a close association between the abundances of these fishes and the abundances of the most frequently used microhabitats, and (2) changes in the abundance of microhabitats would result in a corresponding change in fish population sizes. We examined habitat associations among obligate coral-dwelling gobies (genus Gobiodon) and then investigated relationships between the spatial and temporal availability of habitats and the abundances of Gobiodon species among locations and among zones on the reef at Lizard Island (Great Barrier Reef). Out of a total of 11 Acropora species found to be used by Gobiodon, each species of Gobiodon occupied 1 or 2 species of Acropora significantly more often than expected from the availability of these corals on the reef. Across reef zones, the abundance of most species of Gobiodon was closely correlated with the abundance of coral species most frequently inhabited. However, the abundance of 1 species, G. axillaris, was not correlated with the availability of most frequently used corals across reef zones or among locations. For G. axillaris, therefore, factors other than habitat availability were more important in determining differences in abundance among zones and locations. Also, correlations between the abundance of 2 species, G. histrio and G. quinquestrigatus, and the coral species they most frequently used was less consistent among locations than among zones. This suggests that the relative importance of habitat availability in determining the abundance of these species of Gobiodon is reduced at the spatial scale of locations around Lizard Island. The population dynamics of Gobiodon during this study were closely linked to the population dynamics of host corals. Because of a crown of thorns starfish (Acanthaster planci) outbreak the abundance of corals declined in particular reef zones. Corresponding with this loss of habitat was a decline in Gobiodon abundance. This study demonstrated that the abundance of habitat specialised fishes can be closely correlated with the spatial and temporal availability of suitable habitats among and within reefs.

Gobiidae · Gobiodon · Acropora · Acanthaster · Habitat associations · Specialisation · Species abundances