Strategic Management Prospects v4.0 Species Forecast Report created on 01 February, 2024

A Species Forecast Report is a summary of currently available information, the predicted 50-year outlook for the species, and potential pathways to recovery through species-specific and landscape-scale actions.

The report collates data from a range of sources including the Victorian Biodiversity Atlas, Strategic Management Prospects (SMP), Specific Needs Assessments, Threatened Species Action Statements, the Genetic Risk Index, and the IUCN Common Assessment Method.

Species Forecast Reports are intended to be used in conjunction with SMP and other spatial outputs in NatureKit, and Action Statements where relevant.

For more information on Species Forecast Reports, SMP and other biodiversity decision support tools, including user guides, visit Choosing actions for nature webpage on the DEECA website.


Species Overview

Taxon ID 1695
Scientific name Engaeus phyllocercus
Common name Narracan Burrowing Crayfish
Group Mussels, decapod crustacea
FFG status Endangered
EPBC status
Narracan Burrowing Crayfish (Image Source: Ken Harris EntSocVic )

Narracan Burrowing Crayfish (Image Source: Ken Harris EntSocVic )


Species description

Description and life history

The Narracan Burrowing Crayfish is a small terrestrial burrowing crayfish belonging to the southern hemisphere crayfish family Parastacidae. The maximum reported carapace length of the Narracan Burrowing Crayfish is 26 mm. The taxon is characterised by the presence of leaf-like uropods and a prominent terminal spine on the inner ramus of the uropod (Horwitz 1990a). Poor dispersal, slow maturation and confinement to discontinuous habitats are common to short-range endemics (Harvey 2002) including the Narracan Burrowing Crayfish. Burrowing crayfish spend most of their time underground and freshly excavated soil at burrow entrances is the most obvious sign of their presence. Surface activity is suspected to be nocturnal (Richardson and Swain 1980) and is linked to dispersal and foraging (Shaw 1996) and breeding (Van Praagh and Hinkley 1999). The diet of burrowing crayfish is predominantly plant-based and consists of roots, decomposing leaves and occasionally, small invertebrates (Lake and Newcombe 1975, Suter and Richardson 1977, Growns and Richardson 1988). The diet of the Lilly Pilly Burrowing Crayfish is not specifically known but is suspected to be similar. Activity is commonly related to seasonal rainfall (Morey and Hollis 1997, Van Praagh and Hinkley 1999). As Engaeus spend most of their life underground the life history for this species remains poorly known. Individuals are almost always intersexed and females with eggs have been found in late September with both male and females in the same burrow system suggesting the species breeds in mid to late spring, carries larva in summer and releases juveniles in late summer (Horwitz 1990a).

Distribution

The 35 known species of the genus Engaeus are endemic to south-east Australia, with most occurring in Victoria and Tasmania (Horwitz 1994). The majority of Engaeus species have small natural distributions so are also known as short-range endemics (Horwitz 1994, Harvey 2002). The Narracan Burrowing Crayfish is a short-range endemic due to its restricted distribution. Engaeus phyllocercus is found in the hills, generally above 120 m in altitude, to the north and west of the eastern Strzelecki Ranges in Gippsland Victoria (Horwitz 1990a, Van Praagh 2018). The species is sympatric with a common and more widespread species, E. hemicirratulus, but microhabitat separation is typically evident between the species, with the former occupying blue grey clay soils in the flood bed regions of ferny gullies, and the latter occupying yellow-orange clay soils on hilltops ( Horwitz 1990a, Van Praagh and Hinkley 1999). Burrows of E. phyllocercus, which are found in the flood bed regions of ferny gullies in wet sclerophyll forest, are connected to the water table, often contain multiple openings with conical pelleted chimneys which are connected by lateral tunnels underneath often under tree fern root mats (Horwitz 1990a, Horwitz 1990b). The range includes as far west as Mt Worth and Strzelecki - Ferndale to the Little Morwell River at Darlimurla in the south east. It is also found in the Sunny Creek catchment just south of Trafalgar (Van Praagh 2018). To the west of their range, they have been found in sparsely vegetated stream banks, surrounded by pasture and in more disturbed areas such as roadside table drains adjacent to remnant vegetation (Van Praagh op. cit.). Van Praagh (2018) provides a detailed distribution map for the species.

Habitat

The Narracan Burrowing Crayfish is predominantly a burrower, spending most of its life underground. It has burrows, consisting of two or more openings which are typically found in the flood bed region of fern tree gullies in wet sclerophyll forest. Each opening carries a conical chimney of pelleted soil of varying height or a wider rim shaped chimney of 1 - 2 cm height. Burrows are sometimes found in groups in which chimney height decreases the further distance they are away from the creek bed (Van Praagh and Hinkley 1999). The burrows descend to lateral ramifications (10-30cm below the surface) below which there may be one or two further descending tunnels (Horwitz 1990a). The lateral ramifications may be situated directly below the root mats of Tree-ferns Dicksonia antarctica and Cyathea spp. (Horwitz 1990). Soils in the flood beds are often high in organic matter, dark and have a high silt component. The species may sometimes be found in the banks of flowing creeks where the burrows have several openings ultimately descending to the deepest level of the water table. These are described as ‘type 2’ burrows by Horwitz and Richardson (1986) which refers to burrows that are connected to the water table and the water is derived from ground water and surface runoff. The crayfish appears to be confined primarily to blue-grey clay soils, however, a site at Darlimurla State Forest had a brown to light grey soil with relatively high coarse sand component (Van Praagh and Hinkley 1999).

Genetic Risk Index

This table contains information on the genetic health of Narracan Burrowing Crayfish, informed by recent work conducted by Monash University and cesar Pty Ltd (Kriesner et al. 2019; Kriesner and Weeks 2020). The project undertook genetic risk assessments of ~1,100 species of flora and fauna found in Victoria and generated a large database of available genetic and demographic data for these species. A framework was developed for combining these parameters into a Genetic Risk Index that classified species broadly into ‘Low’, ‘Moderate’, ‘High’, ‘Very High’ and ‘Uncertain’ risk categories. The Genetic Risk Index will continue to undergo refinement and validation to provide further insight into the genetic health of species in Victoria.

Total Australian population size Unknown
Australian distribution Only occurs in Victoria
Dispersal capacity Low: ~1km
Reproductive mode Sexual: species reproduces sexually via male and female gametes
Average generation time One generation every 6 - 10 years
Victorian population trend since ~1975 Unknown
Inbreeding evidence Not assessed
Genetic diversity Not assessed
Genetic rescue potential Uncertain
Genetic Risk Index Uncertain


Species maps

Habitat Distribution Model

The Habitat Distribution Model (HDM) layer shows the modelled distribution of habitat for Narracan Burrowing Crayfish in Victoria. Red shading indicates areas of habitat with relatively higher suitability, compared with yellow shaded areas. HDMs are developed by combining Victorian Biodiversity Atlas (VBA) occurrence records for the species with a range of environmental variables to predict where the most suitable habitat for the species is in Victoria. Species may not always occupy areas of suitable habitat. Threatening processes (prior or ongoing) and disturbance regimes (e.g. fire, timber harvesting) may stop species from occupying otherwise suitable habitat for periods of time. Management actions often focus on currently occupied areas, however management of unoccupied areas can also be important to allow populations to re-establish.

No Habitat Distrabution Model is currently available.


Species Forecast

No Species Forecast data is available because Narracan Burrowing Crayfish is not yet included in our decision-support tools.

About Species Forecast

A Species Forecast is the estimated likelihood of a species being present in 50 years time. The data for Species Forecasts is drawn from DEECA’s decision support tools, Strategic Management Prospects and Specific Needs Assessments.

Many species benefit from the management of widespread threats, such as weeds and pests, and the benefit of these landscape-scale actions to ~4,200 species is modelled in Strategic Management Prospects. In addition to landscape-scale actions, some species also need actions that improve or protect habitat at certain sites, such as nest boxes or hollow logs, or actions to improve certain populations, such as gene mixing or translocation.

As part of a continuous improvement program for our decision-support tools, we are working to expand the scope of actions modelled in Strategic Management Prospects, and to build the dataset of species benefits from location-specific and population-specific actions.

We can use this data to consider how different actions may benefit a species and examine how different types of on-ground management may contribute to a species’ recovery in 50 years, to develop a Species Forecast.


Potential actions for species recovery

No Species Forecast data is available because Narracan Burrowing Crayfish is not yet included in our decision-support tools.


Species prospects in SMP

The benefit data in SMP can be used to consider what the Narracan Burrowing Crayfish’s prospects are if the landscape scale management actions in SMP are implemented.

No Species Prospects figure is available becuase Narracan Burrowing Crayfish is not yet included in SMP.


How to get further information and provide feedback

For more information on the decision support tools, products and underlying data used in this report, and how the data is collected and developed into products, please visit the following links:

These links include information on how to provide data and feedback into these products.

The Species Forecast Reports will be updated periodically to reflect changes and improvements in the products and tools that inform them (e.g., following updates to SMP).

As the data contained in Species Forecast Reports is drawn from multi-species datasets, it is not currently possible to incorporate species-specific information or feedback directly.

For help or further information get in touch by visiting Choosing actions for nature webpage on the DEECA website.


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