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 Endangered
Listing and Conservation Advices Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
 
Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
 
Recovery Plan Decision Recovery Plan not required, included on the Not Commenced List (1/11/2009).
 
Adopted/Made Recovery Plans
Other EPBC Act Plans Burrowing Crayfish (Engaeus) Group Recovery Plan 2001-2005 (Doran, N., 1999b) [Recovery Plan].
 
Policy Statements and Guidelines Draft referral guidelines for four threatened Tasmanian burrowing crayfish (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011s) [Admin Guideline].
 
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 (37) (26/10/2005) (Commonwealth of Australia, 2005b) [Legislative Instrument].
 
State Government
    Documents and Websites
TAS:Tasmania's Freshwater Burrowing Crayfish (Department of Primary Industries and Water (DPIW), 2007) [Information Sheet].
TAS:Engaeus granulatus (Central North Burrowing Crayfish): Species Management Profile for Tasmania's Threatened Species Link (Threatened Species Section (TSS), 2014sh) [State Action Plan].
State Listing Status
TAS: Listed as Endangered (Threatened Species Protection Act 1995 (Tasmania): September 2012 list)
Non-statutory Listing Status
IUCN: Listed as Critically Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
Scientific name Engaeus granulatus [78959]
Family Parastacidae:Decapoda:Malacostraca:Arthropoda:Animalia
Species author Horwitz, 1990
Infraspecies author  
Reference  
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

Scientific name: Engaeus granulatus

Common name: Central North Burrowing Crayfish

The species is conventionally accepted (Horwitz 1990a).

The Central North Burrowing Crayfish is a small crayfish with an average body length under 10 cm. This species is characterised by the granulated surface of the chelae (claw) (Horwitz 1990a).

The Central North Burrowing Crayfish only occurs in central north Tasmania. The species is found in a triangular area running south-west from Port Sorell to the Railton area and north to Quoiba, near Devonport (Nelson 2003).

The species was first described in 1990 (Horwitz 1990a). Little survey work was conducted prior to 2002–2003 studies (Nelson 2003). This work found that the Central North Burrowing Crayfish is confined to seven geographically isolated areas, with a minimum of five kilometres separating each area (Nelson 2003). The species was found to have a restricted, fragmented population with limited connectivity between populations. It is highly probable that known populations will remain isolated due to the modified environments separating them and the continuing threatening processes operating throughout the range of the species (Nelson 2003).

Based on the distribution and abundance of other burrowing crayfish, it is likely that this species was quite common throughout its range prior to its habitat becoming highly modified (Nelson 2003).

The estimated extent of occurrence of the Central North Burrowing Crayfish is 512 km² (Richardson et al. 2008). The maximum area of occupancy of the Central North Burrowing Crayfish is estimated at 0.5 km². Estimates of area of occupancy have been based around known colonies with a buffer applied to waterways and suitable wet areas within each colony to give an overall estimate of potentially occupied habitat (Nelson 2003).

The range of the Central North Burrowing Crayfish was surveyed during 2002–03 (Nelson 2003) on behalf of the Burrowing Crayfish Recovery Team, which oversees implementation of the Burrowing Crayfish Recovery Plan 2001-2005 (Doran 1999b).

Population estimates for the Central North Burrowing Crayfish are based on detailed population density information available for the Scottsdale Burrowing Crayfish (Engaeus spinicaudatus). These population estimates identify a difference in burrowing crayfish density between disturbed and undisturbed land (Horwitz 1991).

Direct observations have produced a population estimate across known sites of between 1000–1500 mature individuals (Nelson 2003). Extending this into potentially occupied habitat around the known colonies (using the burrow density figures of 0.55/m² for undisturbed habitat and 0.05/m² for disturbed habitat; tenure/disturbance breakdown; and the area of occupancy) provides a maximum population estimate of 188 000 mature individuals and a minimum population estimate of 20 000 mature individuals. This minimum is likely to be a substantial overestimate because of the lower relative abundance of the Central North Burrowing Crayfish to that of other burrowing crayfish species and the large buffer around colonies used in the calculations (TSSC 2005br). The population range may be between 8000 and 312  000 individuals. In both cases, population numbers are extremely low for an invertebrate species, particularly considering the range over which it is found (TSSC 2005br).

Horwitz (2004, pers. comm.) argues that, on the basis of habitat change alone, it is possible the species would have experienced a serious decline in the past 100 years, with a potential decline greater than 80% over any ten year period, or three generations.

The Central North Burrowing Crayfish has not been recorded from any secure conservation reserves, despite intensive survey in these areas (Nelson 2003).

The Central North Burrowing Crayfish occupies seeps, wetlands and stream banks in relatively undisturbed habitats. The species is only rarely seen above ground or in standing water. Their burrows exhibit characteristic chimneys of pelleted soil (Horwitz 1990a).

The Central North Burrowing Crayfish is often found in more clayey soils with deeper burrows than other Engaeus species. Burrows can be complex and extensive and may often be the product of several generations of crayfish activity (Doran & Richards 1996).

The Central North Burrowing Crayfish mates in mid to late spring (Horwitz 1990a). Eggs and larvae are incubated in late spring and early summer with juveniles hatching in mid to late summer and released from the burrow when water levels are high. During the breeding season females carry large orange eggs and recently hatched young under their tail (Nelson 2003).

The generation length of the Central North Burrowing Crayfish is approximately three years (Horwitz 2004, pers. comm.).

The Central North Burrowing Crayfish is believed to eat rotting wood, detritus, root material and, occasionally, animal material (Doran 1999b).

The dispersal of the Central North Burrowing Crayfish through waterways may be limited, leading to restricted ranges and a high degree of local speciation (Doran 1999b).

Distinctiveness
The Engaeus genus, which includes the Central North Burrowing Crayfish, can be distinguished from other freshwater crayfish on the basis of size (Engaeus species are very small); claw orientation and shape; carapace (shield covering the back) grooves; and the location and number of spines on the body (DPIW 2007; Horwitz 1988).

Survey methods
The following survey methods were developed during a workshop in June 2010 are recommended for presence/absence surveys (Tasmanian Burrowing Crayfish Workshop 2010). Where it is not possible to conduct surveys in this manner, failure to detect burrowing crayfish should not be considered indicative of their absence.

Surveys should:

  • maximise the chance of detecting the species
  • determine the context of the site within the broader landscape
  • account for uncertainty and error (such as false presences and absences)
  • be conducted by a suitably qualified person with experience in burrowing crayfish surveys, or in consultation with burrowing crayfish experts.

Visual search
The first step in surveying for burrowing crayfish is a visual search to locate burrows within suitable habitat. Presence of burrows in suitable habitat indicates the presence of burrowing crayfish. The recommended minimum search effort is one hour per hectare (Tasmanian Burrowing Crayfish Workshop 2010).

Species identification
In areas where only one burrowing crayfish species occurs, the presence of crayfish burrows confirms the presence of that species. However, in some areas, more than one crayfish species may be present (that is, the species occur together). In an area of overlapping distributions, further investigation is needed once burrows have been located to determine the species occupying a particular microhabitat. This will usually involve burrow excavation. Burrow excavation surveys must be designed and implemented in a way that minimises the disturbance to habitat at the site and should only be conducted in consultation with burrowing crayfish experts. Survey methodology should include appropriate protocols for hygiene control to avoid the spread of pathogens such as chytrid fungus and Phytophthora in crayfish habitat. Permits may be needed for burrow excavation surveys (Tasmanian Burrowing Crayfish Workshop 2010).

Current levels of habitat disturbance
Around known colonies of the Central North Burrowing Crayfish, nearly all land within potential habitat is disturbed. The species' range is highly modified by agriculture, forestry and urban development. Approximately 86% of the species' known habitat occurs on private and public land subject to disturbance and modification, with a further 11.5% existing in state forest (Walker-Smith 2004, pers. comm.).

The species is apparently tolerant of clearing and agricultural development, occurring naturally in small and scattered colonies inlcuding in farm, suburban, and industrial forest surrounds. However, severe and prolonged disturbance could eliminate the species (TSSC 2005br).

Threats to habitat
The Central North Burrowing Crayfish may be impacted by activities that severely alter water quality or quantity or soil and food availability. The species' habitat may also be affected by poor waste management; waterway pollution; the inappropriate application of pesticides and fertilisers; and degradation through the establishment of weeds such as Gorse (Ulex europaeus) and Blackberries (Rubus species) in waterways and seeps (TSSC 2005br).

While all of these impacts have the potential to affect burrowing crayfish habitat over the long term, this species is most at risk from these activities at periods when it is moulting, visiting the surface, mating or nurturing young (Horwitz 1991).

Introduced pests
The Freshwater Yabby (Cherax destructor) has been recorded from a dam where Central North Burrowing Crayfish were present. The Freshwater Yabby is not native to Tasmania and is regarded as an introduced pest. It may pose a threat to the Central North Burrowing Crayfish through competition for food and habitat (DPIW 2007; Nelson 2003).

Low population vigour
The Central North Burrowing Crayfish has low population vigour compared to other members of the same genus. Other burrowing crayfish species tend to produce highly active colonies with large numbers of individuals and burrows present at any one site (Nelson 2003).

Potential threats
Potential threats include: the clearing of vegetation along rivers and drains; ploughing; dam construction; unrestricted stock grazing (which churns and compacts the soil); burning; conversion to plantation (which imposes significant mechanical disturbance on stream headwaters and seepage channels); frequent high intensity fires that have negative long term effects on soil and vegetation; the establishment of roads and associated drainage activities that impact on seep, wetland and stream bank habitat quality (e.g. through the promotion of siltation and erosion); and other activities that degrade river bank integrity and enhance erosion (DPIW 2007).

Over 2001–02, funding was provided to the Tasmanian government through the National Heritage Trust Endangered Species Program to prepare and implement the Burrowing Crayfish (Engaeus) Recovery Plan 2001-2005 for several species of Burrowing Crayfish. Survey work undertaken as part of this project led to the recommendation that the Central North Burrowing Crayfish should also be protected as a threatened species (TSSC 2005br).

Other suggested conservation measures for the Central North Burrowing Crayfish include targeting of private landowners for conservation covenants, creating new reserves, establishing Waterwatch monitoring programs in catchments (Marsden 2005, pers. comm.) and protecting existing colonies (Richardson 2004, pers. comm.).

Increased public awareness and involvement in threatened species protection through community education and involvement will also greatly assist the recovery process for this species. Through the work of the Burrowing Crayfish Recovery Team, public awareness of several other Tasmanian burrowing crayfish has been raised through school and community talks and through a series of magazine, press and newspaper articles (Doran 1999b).

Management documents for the Central North Burrowing Crayfish Engaeus granulatus include the Conservation Advice on Engaeus granulatus (TSSC 2008xv).

The Burrowing Crayfish (Engaeus) Recovery Plan 2001-2005 is available for several Engaeus species (Doran 1999b). It does not specifically include the Central North Burrowing Crayfish, however, many of its recommendations are applicable to the Central North Burrowing Crayfish.

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 Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Agriculture and Aquaculture:Livestock Farming and Grazing:Grazing pressures and associated habitat changes Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Biological Resource Use:Logging and Wood Harvesting:Habitat disturbance due to foresty activities Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat modification with associated erosion Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Restricted geographical distribution (area of occupancy and extent of occurrence) Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Ulex europaeus (Gorse, Furze) Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Rubus fruticosus aggregate (Blackberry, European Blackberry) Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Negative impact from animals Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Changes to hydrology including construction of dams/barriers Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Pollution:Pollution:Habitat degradation and loss of water quality due to salinity, siltaton, nutrification and/or pollution Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Pollution:Pollution:Pestitcide application and runoff Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Protected status:Protected status:Lack of secure conservation land tenure Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus) (Threatened Species Scientific Committee (TSSC), 2005br) [Listing Advice].
Residential and Commercial Development:Residential and Commercial Development:Habitat modification (clearance and degradation) due to urban development Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].
Transportation and Service Corridors:Roads and Railroads:Development and/or maintenance of roads Commonwealth Conservation Advice on Engaeus granulatus (Threatened Species Scientific Committee (TSSC), 2008xv) [Conservation Advice].

Department of Primary Industries and Water (DPIW) (2007). Tasmania's Freshwater Burrowing Crayfish. [Online]. Hobart, Tasmania: DPIW. Available from: http://www.dpiw.tas.gov.au/inter.nsf/WebPages/LJEM-73J92W?open.

Doran, N. (1999a). Survey of the burrowing crayfish at a proposed dam site for Forester River Farms Pty Ltd, with recommendations for managing the development. Report on behalf of the Threatened Species Unit, Parks and Wildlife Service. Tasmania: Department of Primary Industries, Water and Environment.

Doran, N. (1999b). Burrowing Crayfish (Engaeus) Group Recovery Plan 2001-2005. [Online]. Tasmania: Parks and Wildlife Service, Department of Primary Industries, Water and Environment. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/burrowing-crayfish/index.html.

Doran, N. & K. Richards (1996). Management requirements for rare and threatened burrowing crayfish in Tasmania. In: Report to the Tasmanian RFA Environment and Heritage Technical Committee. [Online]. Hobart: Tasmanian Public Land Use Commission, Forestry Tasmania. Available from: http://www.daff.gov.au/rfa/regions/tasmania/environment/crayfish.

Horwitz, P. (1988). A key to the genera of Tasmanian freshwater crayfish. The Tasmanian Naturalist. 94:1-3.

Horwitz, P. (1990a). A taxonomic revision of species in the freshwater crayfish genus Engaeus Erichson (Decapoda: Parastacidae). Invertebrate Taxonomy. 4:427-614.

Horwitz, P. (1991). The conservation biology of Engaeus spinicaudatus, a threatened crayfish from north-eastern Tasmania. Report to the Australian National Parks and Wildlife Service, Canberra.

Horwitz, P. (2004). Personal communication.

International Union for Conservation of Nature (IUCN) (2010). IUCN Red List of Threatened Species. Version 2010.4. [Online]. Available from: http://www.iucnredlist.org.

Marsden, G. (2005). Personal communication.

Nelson, J. (2003). Unpublished Report to the Burrowing Crayfish Recovery Team on Engaeus granulatus survey work as of July 2003. Threatened Species Unit, Tasmanian Department of Primary Industries, Water and Environment.

Richardson, A., S. Hopgood-Douglas, S. Munks, N. Doran & D. Peters (2008). Predicting the distribution of a threatened freshwater burrowing crayfish: Engaeus granulatus in central northern Tasmania. Freshwater Crayfish. 16:43-46.

Richardson, A.M.M. (2004). Personal communication.

Tasmanian Crayfish Workshop (2010). Proceedings of the Tasmanian Crayfish Workshop, 28-29 June 2010. Devonport, Tasmania.

Threatened Species Scientific Committee (TSSC) (2005br). Commonwealth Listing Advice on North Central Burrowing Crayfish (Engaeus granulatus). [Online]. Available from: http://www.environment.gov.au/biodiversity/threatened/species/engaeus-granulatus.html.

Threatened Species Scientific Committee (TSSC) (2008xv). Commonwealth Conservation Advice on Engaeus granulatus. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/78959-conservation-advice.pdf.

Walker-Smith, G. (2004). Personal communication.

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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). Engaeus granulatus in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sat, 12 Jul 2014 02:24:22 +1000.