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Euastacus dalagarbe

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA ARTHROPODA MALACOSTRACA DECAPODA PARASTACIDAE

Scientific Name: Euastacus dalagarbe
Species Authority: Coughran, 2005

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Coughran, J. & Furse, J.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): Livingston, F., 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 dalagarbe has been assessed as Critically Endangered B1ab(iii). This species is endemic to New South Wales, Australia where it has a very restricted range with an extent of occurrence of approximately 41 km2. This species has very specific habitat requirements and as such is susceptible to changes in its habitat due to anthropomorphic or natural changes. As it also has a severely fragmented distribution with only eight localities being recorded, it is susceptible to stochastic events. In the future it is likely to be heavily affected by anthropogenic climate change restricting its range still further and resulting in population declines. Conservation measures are required to protect known habitat from any further degradation.

Geographic Range [top]

Range Description: This species is known from small gullies and creeks feeding a few creeks in the BorderRangesNational Park in New South Wales (Coughran 2005). It is known from eight localities, and has an extent of occurrence of approximately 48.5 km2 (Coughran 2007). The species is restricted to rainforested headwater streams and gullies above 570 m above sea level. The isolated sites thus constitute a fragmented overall distribution, due to the effective barrier to dispersal by intervening lowland areas (Morgan 1997, Ponniah and Hughes 2006).
Countries:
Native:
Australia (New South Wales)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

There are no population data available for this species. It is uncommon at the sites at which it is found (J. Coughran and J.M. Furse pers. comm. 2008).

Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology:

This species occupies a range of habitat types including gullies, tributaries and headwater streams. Individuals were taken from both shallow excavations under rocks, and complex burrow networks. All sample sites were within closed forest cover. Many of the sites lacked standing water (J. Coughran and J.M. Furse. pers. comm. 2008).

The slow growth rate and low fecundity of many Euastacus renders them less resilient to reduction in population numbers through habitat destruction and catastrophic events (Van Praagh 2003).

Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is illegally collected.

Threats [top]

Major Threat(s): Although this species occurs within a national park it is still susceptible to threats such as climate change (Chiew and McMahon 2002, Howden 2003, Hughes 2003, Pittock 2003, Hennessy 2006, Westoby and Burgman 2006, IPCC 2007). This species will be significantly impacted by climate change in two ways; first the increase in temperature may restrict this species to higher altitudes, where the habitat is more thermally suitable. Second, climate change may result in the upper extremities of their montane habitats becoming drier. This could cause the lowering of superficial water tables upon which they appear to rely, thus restricting their upper altitudinal range (Coughran 2007). This will potentially lead to a population and distribution decline (Coughran 2007).

As this species does occur in an area of high visitation there is a very real risk of pollution or infection (Coughran 2007). Wildfire or management burns may also lead to siltation and deoxygenation of habitats. Although illegal collecting for personal collection and preserved material is relatively low-level, it may pose a considerable threat to this species given its extremely restricted distribution (J. Coughran and J.M. Furse pers. comm. 2008).

In recent years, the Cane Toad has been found in high altitude rainforest habitats, including sites inhabited by this species and is of direct concern (DEH 2004b; Coughran 2007). Other exotic species (cats, foxes, pigs, goats) that have generally been found to impact on crayfish (e.g. 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). Given the highly restricted distribution of this crayfish, these exotic species could contribute to serious declines in distribution and/or local abundance (J. Coughran and J.M. Furse pers. comm. 2008). 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 (goats, feral pigs, foxes 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 distribution range falls within the BorderRangesNational Park. Further research should be initiated to include population assessment and monitoring, biological and life history information, habitat requirements, investigations into thermal tolerance and resilience to exotic species (J. Coughran and J.M. Furse. pers. comm. 2008).  

In New South Wales, a minimum recreational size limit of 90mm Orbital Carapace 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. Coughran and J.M. Furse. pers. comm. 2008).


Citation: Coughran, J. & Furse, J. 2010. Euastacus dalagarbe. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 03 September 2014.
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