Boundaries

The southern boundary of the ecoregion is the Great Sandy Desert.  The ecoregion begins in the west with the Fitzroy Basin (Western Australia) and extends east up to and including the King George Basin.

Topography

The ecoregion is dominated by rugged sandstone and limestone ranges and the Kimberley Plateau.  Maximum elevations are up to 937 m (Mt.Ord) with most of the ecoregion being between 200-600 m.  Due to the rugged topography, Kimberley Ecoregion contains more gorges than any other part of Australia.  These gorges likely provide important long-term refuges for fishes during dry periods (Unmack 2001). 

Freshwater habitats

This ecoregion is relatively small, covering 195,000 square kilometers or 2.5% of Australia.  Large rivers with strongly seasonal flow patterns dissect the complex topography of this region.  Many canyons or gorges are present due to the rugged topography.  These provide important long-term refuges for the fauna during dry periods.  No major dams exist within this ecoregion.

Terrestrial habitats

Wooded grasslands and shrublands are the dominant vegetation types.

Description of endemic fishes

Fifteen species including two genera are endemic: Kimberleyeleotris (Eleotridae) and Hannia (Terapontidae). Five of nine species in the family Eleotridae are endemic (Hypseleotris ejuncida, slender gudgeon H. regalis, Prince Regent gudgeon, H. kimberleyensis, Barnett River gudgeon, Kimberleyeleotris hutchinsi, Mitchell gudgeon, K. notata, Drysdale gudgeon); four of nine Terapontidae (Hephaestus epirrhinos, long-nose sooty grunter, Leiopotherapon macrolepis, large-scale grunter, S. trigonicus, long-nose Grunter, Hannia greenwayi, Greenway\'s grunter); two of three Atherinidae (Craterocephalus helenae, Drysdale hardyhead, C. lentiginosus, Prince Regent hardyhead); two of five Melanotaeniidae (Melanotaenia gracilis, slender rainbowfish, M. pygmaea, pygmy rainbowfish); and one of two Toxotidae (Toxotes kimberleyensis, Kimberley archerfish). Several endemics have ranges limited to only one or two individual rivers. Overall 15 out of 48 species are endemic (31%).

Justification for delineation

The complex topography of the Kimberley and its gorges have provided some refuge from historic climate change, thus contributing to the development of a distinctive and endemic biota.  The ecoregion has a mix of relatively widespread species across northern Australia in addition to a large number of endemic species (Unmack 2001).  This suggests that some species have had little trouble dispersing into this ecoregion, but others, based on their limited distributions are unable to disperse under current conditions.  A total of 15 species are endemic from a total of 48 (31%).

Level of taxonomic exploration

Good/Fair. While many aspects of the distribution and ecology of Kimberley fishes are poorly known, a number of species are relatively well characterized taxonomically, but many areas remain poorly sampled. Morgan et al. (2002) considered that there may be an undescribed Ambassis species from this ecoregion and it appears likely that populations of Neosilurus hyrtlii, Hyrtl’s catfish, may be separated into different species (P. Unmack unpub. data). It is possible that local populations of other widespread species may represent undescribed taxa.