Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Critically Endangered
Listing and Conservation Advices Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
 
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
 
Recovery Plan Decision Recovery Plan not required, "the approved conservation advice for the species now provides sufficient direction to implement priority actions and mitigate against key threats. Further actions are being implemented as described in the Western Australian Department of Environment and Conservation's 'Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaewa walpolea) Recovery Plan 2007-2016. Interim Recovery Plan No. 41' (14/04/2009)".
 
Adopted/Made Recovery Plans
Federal Register of
    Legislative Instruments
Inclusion of species in the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (79) (14/04/2009) (Commonwealth of Australia, 2009n) [Legislative Instrument].
 
State Government
    Documents and Websites
WA:Draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2016 (Western Australian Department of Environment and Conservation (WA DEC), 2008a) [State Recovery Plan].
State Listing Status
WA: Listed as Critically Endangered (Wildlife Conservation Act 1950 (Western Australia): September 2013 list)
Non-statutory Listing Status
IUCN: Listed as Critically Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
Scientific name Engaewa pseudoreducta [82674]
Family Parastacidae:Decapoda:Malacostraca:Arthropoda:Animalia
Species author Horwitz & Adams, 2000
Infraspecies author  
Reference Horwitz, P. & Adams, M. 2000 Invertebrate Taxonomy 14: 655-680 [670 figs 7C, 8B, 9B]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

The current conservation status of the Margaret River Burrowing Crayfish, Engaewa pseudoreducta, under Australian and State Government legislation is as follows:

National: Listed as Critically Endangered under the Environment Protection and Biodiversity Conservation Act 1999.

Western Australia: Listed as Critically Endangered under the Wildlife Conservation Act 1950.

Scientific name: Engaewa pseudoreducta

Common name: Margaret River Burrowing Crayfish

The taxonomic status of the Margaret River Burrowing Crayfish is conventionally accepted (Horwitz & Adams 2000).

The Margaret River Burrowing Crayfish is a small crayfish up to 50 mm in length. The species has a pale to mid-brown coloured body, with purplish-blue claws. The abdomen is often narrower than the head and thorax. Other distinguishing features are the small eye, and large claws adapted for digging. The fingers of each claw move in a vertical plane (Horwitz & Adams 2000).

The Margaret River Burrowing Crayfish is only distinguished from other Engaewa species, such as the closely related species Dunsborough Burrowing Crayfish ( E. reducta) and Walpole Burrowing Crayfish (E. walpolea) by examining anatomical features under a microscope. These include: the absence of rostral carinae (raised ridges on the upper surface of the head) and the absence of pits or pores on the lateral processes (side projections) of the 3rd and 4th pereopods (walking legs). However, these species are more easily distinguished from each other by the river system in which they are found, as they have extremely limited capacity for dispersal and are geographically isolated (Horwitz & Adams 2000).

The Margaret River Burrowing Crayfish is endemic to south-western Western Australia. The species is known only from only two populations in swampy headwaters of a tributary of the Margaret River, near Osmington, 250 km south of Perth. One of these populations, from which the species was first collected, is presumed extinct. The locations are less than 2 km apart (TSSC 2009h; WA DEC 2008a).

The Margaret River Burrowing Crayfish has an area of occupancy of less than 1 km². This area of occupancy has been created by measuring suitable habitat around areas where individuals have been found (TSSC 2009k). Much of this area has not been well surveyed due to the difficult vegetation that needs to be traversed (WA DEC 2008a). The discovery site of the Margaret River Burrowing Crayfish, a swamp area of a drainage line in the Treeton Forest Block, is considered to have an area of occupancy of less than 0.025 km². The species has not been rediscovered at this site since 1985 (WA DEC 2008a).

The distribution of the two known populations is isolated and subject to a number of threats including land clearing for agriculture and forestry, cattle grazing, feral pigs, road and bridge construction and ground water extraction (Burnham 2005; Burnham et al. 2007).

There are no population estimates for the Margaret River Burrowing Crayfish, though numbers are likely to be low based on the highly restricted area the species is known from (TSSC 2009k).

The generation length of the Margaret River Crayfish is unknown, however they are considered to be long-lived with slow maturation (WA DEC 2008a).

The population of the Margaret River Burrowing Crayfish occurs in Treeton Forest Block, a State Forest tenure. Protection of suitable habitat surrounding a stream on private property close by is being undertaken (WA DEC 2008a).

The Margaret River Burrowing Crayfish lives in the narrow, creek tributaries of the Margaret River in areas of dense vegetation that includes tea-trees (Melaleuca spp.) and eucalypts (Eucalyptus spp.). Soils are heavy grey-yellow clays (TSSC 2009h).

The Margaret River Burrowing Crayfish construct complex burrow systems that can extend several metres deep to freshwater watertables in the drier months. A chimney of soil pellets is an indicator of burrow systems, often seen in the wetter periods (TSSC 2009h). These chimneys are however not as conspicuous as those built by other Engaewa species (WA DEC 2008a), and this combined with the often impenetrable vegetation of the area, may explain why the species has not been found during surveys.

Several surveys of the type site where the Margaret River Burrowing Crayfish was first recorded have been conducted with no individuals found. Surveys of the second site in the Treeton Forest Block have not been undertaken. However suitable habitat surrounding the population was undertaken in 2005 and 2006 with no individuals found (WA DEC 2008a). The chimneys of the Margaret River Burrowing Crayfish burrows are not as conspicuous as those built by other Engaewa species, and this combined with the often impenetrable vegetation of the area, may explain why the species has not been found during surveys (WA DEC 2008a).

The main threat to the Margaret River Burrowing Crayfish is habitat loss caused by human or human-linked disturbance within the species' very limited range. Land clearing for agriculture and forestry has removed habitat for the species and may have increased salinity in habitats utilised by the species. Farm dam construction has flooded suitable habitat and has altered surface water and groundwater flows. Cattle grazing has physically destroyed burrows through trampling and soil compaction, and has created serious erosion and has impaired soil permeability and water holding capacity (Burnham 2005; Burnham et al. 2007; Horowitz & Adams 2000).

Potential threats to the Margaret River Burrowing Crayfish include drainage for peat, sand mining or agriculture activities, which can desiccate the species' moisture-rich habitats and water extraction from bores, which can lower water tables and potentially cause acidification and mobilisation of toxic metal ions in wetlands.

Feral pigs (Sus scrofa) are an additional threat, as feral pig numbers are increasing in south-western Western Australia due to illegal introductions by recreational pig hunters and subsequent reproductive success. Feral pigs may damage habitat through ground-rooting feeding behaviour and directly prey on crayfish during rare surfacing events (Spencer & Hampton 2005).

Further threats that have not been quantified but may be detrimental to the Margaret River Burrowing Crayfish include fire, road and bridge construction, disease from introduced crayfish species, exposure and subsequent hydration of acid sulphate soils, use of pesticides, fertilisers or herbicides that contaminate or reduce water quality, and climate change reducing rainfall and wetland habitats (Burnham 2005; Burnham et al. 2007).

The impacts of fire on the Margaret River Burrowing Crayfish have not been closely examined. However, it is suggested that, whilst not directly threatening individual Margaret River Burrowing Crayfish, burning may alter the water holding capacity of habitat such as peatlands, and alter the soil structure making it both more prone to future fires and less suitable for the species through acidification and metal toxification. Fire fighting techniques could also be detrimental to a species with such a restricted distribution (WA DEC 2008a).

Minister's reasons for recovery plan decision

The approved conservation advice for the species now provides sufficient direction to implement priority actions and mitigate against key threats. Further actions are being implemented as described in the Western Australian Department of Environment and Conservation's 'Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engawea pseudoreducta) and Walpole Burrowing Crayfish (Engaewa walpolea)Recovery Plan 2007-2016. Interim Recovery Plan No. 41'.

A nationally adopted recovery plan is not considered to be necessary at this time.

Other recovery actions

The draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2010 (WA DEC 2008a) outlines the following recovery objectives for these species:

  • determine the current distribution and identify additional populations of Engaewa
  • increase public awareness and participation in threatened species protection
  • protect habitat
  • improve knowledge of Engaewa life history and ecology.

The Conservation Advicefor the Margaret River Burrowing Crayfish (TSSC 2009h) outlines research priorities and priority actions for the protection of the species. These include:

  • Research the species life history (longevity, dispersal, reproduction).
  • Research the species ability to withstand desiccation, acidity and low dissolved oxygen levels and effects of fire.
  • Design and implement a monitoring program, including improved ways of catching and releasing animals for study (currently animals must be dug out by hand).
  • Undertake survey work in suitable habitat and potential habitat to locate any additional populations/occurrences.
  • Monitor known populations to identify key threats.
  • Monitor the progress of recovery, including the effectiveness of management actions and the need to adapt them if necessary.
  • Minimise adverse impacts from land use at known sites, particularly agriculture and forestry operations.
  • Manage any disruptions to water flows to minimise impact on surface water and groundwater flows such as farm dam construction, drainage activities, agricultural, forestry or mining operations, or groundwater extraction.
  • Manage known sites to prevent introduction of invasive weeds, which could become a threat to the Margaret River Burrowing Crayfish, using appropriate methods.
  • Prevent habitat degradation/destruction by cattle and sheep grazing at known sites.
  • Manage feral pigs at known sites to minimise impacts from ground-rooting and wallowing.
  • Manage feral pigs at known sites to minimise impacts from predation.
  • Implement an appropriate fire regime for the habitat of local populations.

The following documents may inform the conservation of this species:

  • Draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2010 (WA DEC 2008a).
  • The Conservation Advice for the Margaret River Burrowing Crayfish (TSSC 2009h).

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Agriculture and Aquaculture:Livestock Farming and Grazing:Habitat alteration (vegetation, soil, hydrology) due to trampling and grazing by livestock Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Biological Resource Use:Hunting and Collecting Terrestrial Animals:Harvesting for recreational purposes Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Biological Resource Use:Logging and Wood Harvesting:Habitat loss, modification and degradation due to timber harvesting Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Climate Change and Severe Weather:Climate Change and Severe Weather:Climate change altering atmosphere/hydrosphere temperatures, rainfall patterns and/or frequency of severe weather events Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Climate Change and Severe Weather:Climate Change and Severe Weather:Reduced rainfall caused by climate change Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Restricted geographical distribution (area of occupancy and extent of occurrence) Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Energy Production and Mining:Mining and Quarrying:Habitat modification through open cut mining/quarrying activities Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Grazing, tramping, competition and/or habitat degradation Sus scrofa (Pig) Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Presence of pathogens and resulting disease Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Natural System Modifications:Dams and Water Management/Use:Changes in hydrology including habitat drainage Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Changes to hydrology including construction of dams/barriers Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Extraction of ground water Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Natural System Modifications:Dams and Water Management/Use:Salinity Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Pollution:Agricultural Effluents:Herbicide application Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Pollution:Pollution:Acid sulphate soils Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Pollution:Pollution:Habitat degradation and loss of water quality due to salinity, siltaton, nutrification and/or pollution Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Pollution:Pollution:Pestitcide application and runoff Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].
Transportation and Service Corridors:Roads and Railroads:Development and/or maintenance of roads Commonwealth Conservation Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009h) [Conservation Advice].
Transportation and Service Corridors:Roads and Railroads:Development of roads and railroads Commonwealth Listing Advice on Engaewa pseudoreducta (Threatened Species Scientific Committee (TSSC), 2009k) [Listing Advice].

Burnham, Q.F. (2005). The systematics of the reducta complex of the burrowing freshwater crayfish Engaewa Riek. Hons. Thesis. Perth: Edith Cowan University.

Burnham, Q.F., A. Koenders & P. Horwitz (2007). Field studies into the biology and conservation requirements of Engaewa species in the South-West and Warren DEC Regions. Final Report Prepared for Department of Environment and Conservation 30 November 2007.

Horwitz, P. & M. Adams (2000). The systematics, biogeography and conservation status of the species in the freshwater crayfish genus Engaewa Riek (Decapoda: Parastacidae) from south-western Australia. Invertebrate Taxonomy. 14:655-680.

Spencer, P.B.S. & J.O. Hampton (2005). Illegal translocation and genetic structure of feral pigs in Western Australia. Journal of Wildlife Management. 69:377-384.

Threatened Species Scientific Committee (TSSC) (2009h). Commonwealth Conservation Advice on Engaewa pseudoreducta. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/82674-conservation-advice.pdf.

Threatened Species Scientific Committee (TSSC) (2009k). Commonwealth Listing Advice on Engaewa pseudoreducta. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/82674-listing-advice.pdf.

Western Australian Department of Environment and Conservation (WA DEC) (2008a). Draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2016. [Online]. Western Australia: Department of Environment and Conservation. Available from: http://www.dec.wa.gov.au/pdf/plants_animals/threatened_species/frps/41-burrowing-crayfish-recovery-plan-01feb2009.pdf.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Engaewa pseudoreducta in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Tue, 2 Sep 2014 12:06:50 +1000.