The ecology of territorial herbivorous damselfish (Genus Parma) on temperate Western Australian rocky reef

[Truncated abstract] The objective of this research was to develop ecological knowledge for fish of the pomacentrid genus Parma. Using Parma mccullochi as a model species I investigated the ecological role of territorial herbivorous pomacentrids in temperate waters. A broad scale geographical study revealed that fish of this genus are common on shallow temperate reefs throughout Western Australia (WA). Parma occidentalis has a northern distribution, with its southern limit at Perth, while Parma victoriae has a southern distribution, with Perth as its northern range limit. P. mccullochi is abundant throughout temperate WA with its peak densities at Perth. The greatest proportion of larger bodied individuals was also recorded on reefs around Perth. The latitudinal separation in species correlates to changes in mean sea surface temperatures (SST), which decrease from north to south. Over its geographical range P. mccullochi is strongly associated with the presence of turfing macroalgae habitat, in areas that are generally dominated by canopy forming macroalgae. At Perth fine scale habitat analysis revealed selection for habitat of high turfing and foliose understorey macroalgae cover, and for high (> 3 m) and vertical reef profile. These results suggest that P. mccullochi preferentially inhabit these areas, as they may fulfil a requirement for both shelter and an algal food resource within the territory. The three common species of Parma in temperate WA may perform similar functional roles, and their distributions may be limited by competition for resources and differing SST requirements.