Biodiversity publications archive

Refugia for biological diversity in arid and semi-arid Australia

Biodiversity Series, Paper No. 4
S.R. Morton, J. Short and R.D. Barker, with an Appendix by G.F. Griffin and G. Pearce
Biodiversity Unit
Department of the Environment, Sport and Territories, 1995

4. Foci of biological diversity in Western Australia (continued)

4.8. Carnarvon

Area

91,960 km².

Primary land-use

Extensive pastoralism, salt mining, fishing, tourism.

National Parks and Nature Reserves

Cape Range National Park, Thevenard Island Nature Reserve, Doole Island Nature Reserve, Kennedy Range National Park, Francois Peron National Park.

Management problems

Existing: Land degradation through over-grazing (Payne et al. 1987; Wilcox and Cunningham 1994).

Dirk Hartog Island: feral cats and goats (Burbidge 1989; Burbidge and George 1978); fox incursions onto islands in Exmouth Gulf not separated from mainland by deep channels, plus house mice and feral pigeons (Start and McKenzie 1992/3).

Cape Range National Park: buffel grass, feral goats (Keighery and Gibson 1993). Thirty taxa of weeds occur on Cape Range peninsula, mostly around the townsite of Exmouth (Keighery and Gibson 1993). Significant weed invasion is reported in Yardie Creek gorge (infestations of Emex australis and Asphodelus fistulosus), and on the western coastal plain (buffel grass Cenchrus ciliaris replacing native Triodia grassland).

Potential: Doole Island and Roberts Island: weed invasions of buffel grass and geranium Erodium cicutarium have a minor presence (Start and McKenzie 1992/3). Cape Range National Park: high tourist use exceeding management capability (Wilson 1987).

Troglobite fauna of Cape Range: changes to ground water levels, mining of limestone (most caves lie within a Temporary Limestone Reserve, in which quarrying could be permitted), unplanned road building within the area (by causing sediments and nutrients to leak into caves and change the water regimes) (Wager and Jackson 1993; Humphreys and Blyth 1994). For boundaries of the Temporary Limestone Reserve see Allen (1993). The troglobite fauna is potentially threatened by the development of Exmouth as a residential and tourist centre (by contamination of groundwater and surrounding waters by excessive nutrients, heavy metals or hydrocarbons) (Humphreys and Blyth 1994). Humphreys and Adams (1991) suggested that the watertable of the North-west Cape Peninsula may be declining and becoming more saline.

ANZECC-listed species

Mammals: Burrowing bettong Bettongia lesueur (E), rufous hare-wallaby Lagorchestes hirsutus (E), banded hare-wallaby Lagostrophus fasciatus (E), western barred bandicoot Perameles bougainville (E), Shark Bay mouse Pseudomys fieldi (E), greater stick-nest rat Leporillus conditor (E).

Birds: A black-plumaged population of the white-winged wren Malurus leucopterus leucopterus (V) occurs on Dirk Hartog Island (Burbidge 1989). The western subspecies of the thick-billed grasswren Amytornis textilis textilis (V) is now confined to the northern Peron Peninsula and perhaps also Dirk Hartog Island (Garnett 1992, pp. 124-5).

Species that are regionally endemic

Reptiles: The gecko Diplodactylus rankini; the agamid Ctenophorus femoralis; the skinks Ctenotus zasticus, C. rufescens, Lerista gascoynensis, L. haroldi, L. onsloviana, L. talpina, L. uniduo and L. varia; and a subspecies of the pygopodid Aprasia rostrata fusca is confined to the Exmouth Gulf area (Cogger 1992).

Cave organisms: See below under relict populations.

Relict populations

Islands of Exmouth Gulf: Rattus tunneyi on Roberts Island and Simpson Island (Start and McKenzie 1992/3).

Cape Range: More than 400 caves and other karst features exist (Humphreys and Blyth 1994). There are two categories: caves of the range itself are often humid but contain little standing water; caverns and voids of the foothills and coastal plains contain fresh to saline water. At least 38 species of troglobites (i.e. species obligatorily dependent upon the cave environment), involving 28 families and 30 genera (10 endemic), plus a large number of species of troglophiles (i.e. species occurring in caves, but which do not display explicit morphological adaptations and which may be found outside them) have been collected from Cape Range (these estimates include the Barrow Island fauna). The troglobites include pseudoscorpions (the genera Tyrannochthonius and Hyella), a schizomide arachnid (Draculoides vinei), an opilionide arachnid (an undescribed genus), species from six families of spiders (Desidae, undescribed genus; Ctenidae, undescribed genus; Miturgidae, undescribed genus; Symphytognathidae, Anapistula sp.; Theridiidae, Steatoda spp.; Linyphiidae, Dunedinia occidentalis and Chthiononetes tenuis), crustaceans from the groups Thermosbaenacea (Halosbaena tulki), Amphipoda (an undescribed eriopisid genus), Isopoda (undescribed genera) and Decapoda (Stygiocaris lancifera and S. stylifera), millipedes (Stygiochiropus communis, S. sympatricus, S. isolatus, and Boreohesperus capensis), a cockroach (Nocticola flabella), bugs (including Phaconeura proserpina), undescribed Orthoptera, and fish (the blind cave gudgeon Milyeringa veritas and the blind cave eel Ophisternon candidum) (Harvey 1991; Harvey et al. 1993; Humphreys 1990, 1993; Humphreys and Adams 1991; Humphreys et al. 1989; Humphreys and Blyth 1994; Humphreys and Shear 1993; Knott 1993; Shear 1992). The affinities of the fauna are varied, but a large element of the terrestrial troglobites is derived from the humid tropics and "is relictual from times when humid forest covered this region" (Humphreys 1993,
p. 165).

The cave gudgeon and the cave eel are the only vertebrate animals known from Australasia that are restricted to either caves or groundwater; they are declared as threatened fauna under the Western Australian Wildlife Conservation Act.

Slack-Smith (1993) noted species of snails on Cape Range that appear to be relicts of formerly more widespread populations. The non-marine fauna consists of two species of aquatic prosobranch gastropods and 16 species of terrestrial pulmonates. Nine species of camaenid snails (in Rhagada, Quistrachia, and three undescribed genera) and one pupillid (Pupoides sp.) are endemic; 56% of the land snails in the area are endemic. Some species have a cavernicolous existence at Cape Range, but occupy a greater diversity of habitats in more humid areas (Slack-Smith 1993).

Among 630 taxa of plants, there are 12 endemic taxa and 6 taxa largely confined to the peninsula (Keighery and Gibson 1993). The Millstream palm Livistona alfredii occurs at the top of Yardie Creek system (Humphreys et al. 1990). There is unusual fringing vegetation along Yardie Creek of Typha domingensis and Schoenoplectus litoralis.

Yardie Creek (Cape Range): The creek system and semi-permanent wetlands of Yardie Creek were identified by Keighery and Gibson (1993) as refugia for a number of southern taxa of plants that reach their northern limit in this area. A species of prosobranch snail Melanoides sp. is recorded only "from a pool upstream of the limit of saline water".

Gorges of Cape Range: Keighery and Gibson (1993, p. 54) list many species of tropical affinity that are found along the gorges and valleys of the western side of Cape Range (the climate is ameliorated by the sea breeze, and valleys are slightly wetter and fire-free).

Bernier Island: Burrowing bettong Bettongia lesueur, rufous hare-wallaby Lagorchestes hirsutus, banded hare-wallaby Lagostrophus fasciatus, western barred bandicoot Perameles bougainville, Shark Bay mouse Pseudomys fieldi.

Dorre Island: Burrowing bettong, rufous hare-wallaby, banded hare-wallaby, western barred bandicoot.

Dirk Hartog Island: The black form of the white-winged wren.

Baudin Island: The skink Egernia stokesii aethiops (Burbidge 1989).

Salutation Island: A reintroduced population of the greater stick-nest rat Leporillus conditor.

Other significant populations

Many of the amphibians and reptiles in the Lake McLeod region are at the northern (8 taxa) or southern limit (23 taxa) of their distributions (Storr and Harold 1984). The burrowing frog Arenophryne rotunda occurs on Dirk Hartog Island, and is found elsewhere only in the Zuytdorp area (Roberts 1990).

Wetland sites

Most of Lake McLeod is ephemeral, filled only occasionally by major flows of the Minilya, Lyndon, and, less frequently, Gascoyne Rivers. However, a part is continually fed by a subterranean flow of water from the Indian Ocean (Lane and McComb 1988), some 20 km distant. Its waters support abundant plant and invertebrate life which in turn provide food for large numbers of fish and many thousands of waterbirds (Smith and Johnstone 1985). A single line of mangroves fringes the inlet channels to the main lake.

The tortoise Chelonia steindachneri is endemic to the North-West Cape coastal plain (Burbidge et al. 1974; Cann 1978).

Refugia

The refugia identified are the North-west Islands (see section 10.3), the islands of Exmouth Gulf (10.5), the islands of Shark Bay (10.6), Dirk Hartog Island (10.7), Bernier and Dorre Islands (10.8), the Cape Range caves and gorges (10.9), Lake McLeod (10.16), and Edel Land, Heirisson Prong and Peron Peninsula (10.31).