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Euastacus guwinus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA ARTHROPODA MALACOSTRACA DECAPODA PARASTACIDAE

Scientific Name: Euastacus guwinus
Species Authority: Morgan, 1997

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Furse, J. & Coughran, J.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.
Justification:

Euastacus guwinus has been assessed as Critically Endangered B1ab(iii)+2ab(iii). It has an extent of occurrence of less than 10 km², an area of occupancy less than or equal to the extent of occurrence, and is only known from one location (from the headwaters of Tianjara Creek). There has been a continuing decline in the quality of habitat due to the destructive nature of a number of exotic species in the area, some of which also predate upon this species. There is also the presence of the invasive species Cherax destructor which predates on this species and out-competes it for habitat space. There is also destruction of suitable rainforest habitat in parts of its range. This species also faces the consequences of global temperature rise. As a restricted range species, dependent on cool, clear headwater streams, a slight increase in temperature could rapidly extirpate this species. Research should be initiated to include population assessment and monitoring, biological and life history information, habitat requirements, and resilience to effects of exotic species.

Geographic Range [top]

Range Description:

This species is endemic to Australia. It is known only from the headwaters of Tianjara Creek (a tributary of the Shoalhaven River), New South Wales (Morgan 1997); at an elevation of 480 m above sea level. Furthermore, it has an approximate extent of occurrence of less than 10 km² (J. M. Furse and J. Coughran pers. comm. 2008); its area of occupancy must be less than or equal to the extent of occurrence.

Countries:
Native:
Australia (New South Wales)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There is no population information available for this species, however it is considered to be extremely rare having been described from only six specimens (Morgan 1997).

Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is known only from the type locality, which is a small stream with sandstone bedrock, lined by dry sclerophyll and heath forest. The site was open and poorly shaded, and crayfish were commonly found under rocks (Morgan 1997).
Systems: Freshwater

Threats [top]

Major Threat(s): Given its highly restricted range, this species is extremely susceptible to localized impacts, including bush fires, forest management practices, habitat destruction and over exploitation by collectors (J. Coughran and J.M. Furse pers. comm. 2009). This species is also susceptible to climate change, including increasing temperature, alterations to hydrological regimes, severe weather events and loss of suitable highland habitat (Chiew and McMahon 2002, Howden 2003, Hughes 2003, Pittock 2003, Hennessy 2006, Westoby and Burgman 2006, IPCC 2007).

Furthermore, an exotic crayfish species, Cherax destructor, is being increasingly recorded throughout the Shoalhaven region (Daley and Craven 2007, McCormack 2008), and may pose a serious threat to this species if present at the locality. Cherax destructor is aggressive, and likely far more prolific and faster growing than this species. As such, it may outcompete native species in a short period of time (Merrick 1995). Other introduced exotic species (cats, foxes, pigs, goats) that have generally been found to impact on crayfish (Green and Osbourne 1981, Horwitz 1990, Merrick 1995, Eyre et al. 1997, ACT Government 2007, O'Brien 2007) also occur in this species' range (DEH 2004a,c,d,e) and given this species highly restricted distribution, could have serious impacts by contributing to declines in its distribution and/or abundance (J. Coughran and J.M. Furse pers. comm. 2009). Due to the narrow thermal tolerance of this species, and its restricted range (restricted to cool, headwater streams in forested catchments), global temperature increase has resulted in range contraction. This species is further compromised by the presence of exotic species (feral pigs, foxes, Cane Toads and cats) which are known to predate on crayfish and degrade riparian habitat; while the precise effects of these threats on this species are not yet well understood, they are believed to be significantly impacting the long term viability of the population (J. Furse and J. Coughran pers. comm. 2010).

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation measures in place for this species, however its range coincides with a national park. In New South Wales, a minimum recreational size limit of 90 mm orbital carpace length is in place for any spiny crayfish (NSW DPI 2007). This species does not attain that size, and so is indirectly protected by this restriction ( J. M. Furse and J. Coughran pers. comm. 2008). Research should be initiated to include population assessment and monitoring, biological and life history information, habitat requirements, additional investigations into thermal tolerance, resilience to and presence of exotic species at its locality are warranted.

Citation: Furse, J. & Coughran, J. 2010. Euastacus guwinus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 23 November 2014.
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