Action statement No.264 Flora and Fauna Guarantee Act 1988 Dandenong Burrowing Crayfish Engaeus urostrictus © The State of Victoria Department of Environment, Land, Water and Planning 2015 This work is licensed under a Creative Commons Attribution 4.0 International licence. You are free to re-use the work under that licence, on the condition that you credit the State of Victoria as author. The licence does not apply to any images, photographs or branding, including the Victorian Coat of Arms, the Victorian Government logo and the Department of Environment, Land, Water and Planning (DELWP) logo. 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This document is also available on the internet at www.delwp.vic.gov.au Action Statement No. 264 Dandenong Burrowing Crayfish Engaeus urostrictus Description to the Dandenong Ranges east of Melbourne. This species has only been recorded from a few The Dandenong Burrowing Crayfish (Engaeus small sub-catchments around Mount Dandenong, urostrictus Riek 1969) is a small terrestrial Sherbrooke, Sassafras and Kallista areas. All known burrowing crayfish belonging to the southern locations of the species are near the headwaters hemisphere crayfish family Parastacidae. The of small streams that flow through predominantly species has a laterally flattened body and a small, forest in the Dandenong Ranges National Park and bristly abdomen (Horwitz 1990). This contrasts the Sassafras Creek Nature Conservation Reserve with the better known Freshwater Yabby (Cherax (Lumsden et al. 2011, DSE 2013a). A historical destructor) which has a dorsoventrally flattened outlying record at Mount Donna Buang in the Yarra body and a larger, non-bristly abdomen (Horwitz Ranges to the east of the Dandenong Ranges is 1990, Horwitz 1995). The Dandenong Burrowing unusual and requires clarification (Horwitz 1990). A Crayfish has a maximum recorded carapace length* further historical record from Bunyip township (DEPI of approximately 20 mm, a short broad rostrum 2013b) is suspected to be erroneous. The species and an almost spineless triangular tail fan (Horwitz is not likely to be found west of Mount Dandenong 1990). The Tubercle Burrowing Crayfish (Engaeus (Horwitz 1990). The related Tubercle Burrowing tuberculatus), co-occurs with the Dandenong Crayfish is sympatric with the Dandenong Burrowing Burrowing Crayfish but is distinguished by a longer Crayfish in the Dandenong Ranges but occupies a carapace length (approximately 33 mm), a long, different habitat (Horwitz et al. 1985). thin rostrum and tufts of long bristles on the ends of the tail fan (Horwitz 1990). The morphology and Habitat detailed descriptions of all known Engaeus species is provided in Horwitz (1990, 1994). The Dandenong Burrowing Crayfish occurs in riparian zones characterised by sandy soil flats *carapace length, also known as the Occipital adjacent to small, slow flowing headwater streams Carapace Length (OCL), is measured from the rear with high organic content. The organic content in of eye socket to the central posterior edge of the the stream and adjacent flats originates from leaf carapace and bark fall (Horwitz et al. 1985). These streams are predominantly located within the Wet Forest Distribution Ecological Vegetation Class (EVC) which occurs The 35 known species of the genus Engaeus on well-drained loamy soils in protected gullies are endemic to south-east Australia, with most and on southern aspects of hills and mountains in occurring in Victoria and Tasmania (Horwitz 1994). high rainfall areas (DSE 2004a). In the Dandenong The majority of Engaeus species have small natural Ranges, the Wet Forest EVC is comprised of distributions, also known as short-range endemics tree ferns (Dicksonia antarctica) and Sassafras (Horwitz 1994, Harvey 2002) and include the (Atherosperma moschatum) with a tall forest of Dandenong Burrowing Crayfish which is restricted Mountain Ash (Eucalyptus regnans) dominating Sassafras Creek (Kaylene Morris) Distribution in Victoria (DELWP, 2015) Action statement No. 264Dandenong Burrowing Crayfish 3 nearby slopes and a moist, shaded, fern-rich been found in late November and early December ground layer (Horwitz et al. 1985, DSE 2004a). with small, ovoid and undeveloped eggs (Horwitz There is one historic record from the foothills of et al. 1985, Horwitz 1990) and juveniles have been Mount Dandenong (DEPI 2013a) in the Grassy Dry found in chambers of burrow systems in June and Forest EVC (DSE 2004b) which is an exception to September (Horwitz et al. 1985). Males and females the species occurrence in the Wet Forest EVC. The of the species have been found in approximately species is known from altitudes of approximately equal ratios with intersexed specimens occasionally 250 - 440 m (Horwitz 1990, DEPI 2013b). found (Horwitz 1990). The Dandenong Burrowing Crayfish builds extensive The life span of the Dandenong Burrowing Crayfish burrow systems with many lateral branches amongst and many other burrowing crayfish species is not buried, rotting plants and roots of ferns, shrubs and known. trees (Horwitz et al. 1985). The riparian burrow systems of the species have tunnels which descend Conservation status to the water table, allowing the crayfish to follow the rise and fall of the water table (Horwitz et al. Victorian conservation status 1985). The species can form chimneys of excavated Dandenong Burrowing Crayfish (Engaeus urostrictus) soil pellets up to 13 cm high. This contrasts with the has been listed as threatened under the Victorian habitat of the Tubercle Burrowing Crayfish which Flora and Fauna Guarantee Act 1988. occupies banks and hill slopes and has burrows independent of the water table being wholly reliant Dandenong Burrowing Crayfish (Engaeus urostrictus) on surface water runoff (Horwitz et al. 1985). has been listed as critically endangered in Victoria according to the Department of Environment, Land, Life History and Ecology Water and Planning (DELWP)’s Advisory List of Threatened Invertebrate Fauna in Victoria – 2009 Burrowing crayfish spend most of their time (DSE 2009). underground and freshly excavated soil at burrow entrances is the most obvious sign of their presence. Surface activity is suspected to be nocturnal Threats (Richardson and Swain 1980) and is linked to The highly restricted distribution of the Dandenong dispersal and foraging (Shaw 1996) and breeding Burrowing Crayfish, poor dispersal and confinement (Van Praagh and Hinkley 1999). Activity is commonly to discontinuous habitats increase the risk of losses related to seasonal rainfall (Morey and Hollis from stochastic or anthropogenic events. Should 1997, Van Praagh and Hinkley 1999). The cryptic extinction of a population occur, chances of re- behaviour of burrowing crayfish means little is colonisation from other populations are presumed known about their life history and ecology, including to be low and genetic decline may be an issue. As the Dandenong Burrowing Crayfish. Poor dispersal, the biology and ecology of the species is poorly slow maturation and confinement to discontinuous understood further investigation into aspects of habitats are common to short-range endemics breeding and dispersal are required to understand (Harvey 2002) such as the Dandenong Burrowing the range of threats to the species. Crayfish. Fire has the greatest capacity to impact the species The diet of burrowing crayfish is predominantly by damaging or destroying habitat. The crayfish plant-based and consists of roots, decomposing occupies Wet Forest EVC, which is not targeted for leaves and occasionally, small invertebrates (Lake planned burning. Bushfire could have a significant and Newcombe 1975, Suter and Richardson 1977, impact as this forest type requires long-term Growns and Richardson 1988). The diet of the recovery from fire. Planned burning in drier EVCs Dandenong Burrowing Crayfish is not specifically can however reduce the risk of fires entering and known. impacting on Wet Forest and crayfish habitat. Breeding in most burrowing crayfish is likely to occur Climate change has the potential to impact water over spring and summer. Males surface during late quality and quantity via reduced rainfall. Changes spring and early summer to search for mates and to hydrological regimes are one of the most serious then enter the burrows of females (Van Praagh and impacts of climate change on freshwater systems Hinkley 1999). Females incubate egg clusters under (e.g. Aldous et al. 2011, Kingsford 2011). This poses the abdomen and the juveniles hatch in late summer a serious threat as the species occupies riparian (Van Praagh and Hinkley 1999). Berried (gravid) habitat. females of the Dandenong Burrowing Crayfish have Action statement No. 264Dandenong Burrowing Crayfish 4 Water quality impacts