Engaeus mallacoota 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Malacostraca Decapoda Parastacidae

Scientific Name: Engaeus mallacoota Horwitz, 1990
Common Name(s):
English Mallacoota Burrowing Crayfish

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Doran, N. & Horwitz, P.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): 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.
Engaeus mallacoota has been assessed as Critically Endangered using criterion B1ab(iii). This species is known from a single location with an estimated extent of occurrence (EOO) of just over 15 km². While this species range falls within a national park, upstream habitat modification and degradation as a result of cattle farming and removal of riparian vegetation is impacting this species' downstream habitat. A number of measures have now been employed to prevent the further loss of upstream riparian strips, however it is not clear if these measures are enough to prevent the further degradation and loss of this species habitat. Monitoring of this species population trends and threats is needed as a single threatening event could result in the extinction of this species.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to Victoria, Australia. The known distribution of this species is confined to two sites on the western region of Mallacoota Inlet, near the Victoria-New South Wales border (Horwitz 1990). This species has an extent of occurrence of approximately 15 km² and is known from a single location.
Countries occurrence:
Australia (Victoria)
Additional data:
Number of Locations:1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There is no population information for this species, however this is not an abundant species (P. Horwitz pers. comm. 2009).
Current Population Trend:Unknown
Additional data:
Population severely fragmented:Unknown

Habitat and Ecology [top]

Habitat and Ecology:Habitat information regarding this species is known only from the type locality. It was found in a creek measuring 1–2 m wide with steep, clear banks (free of vegetation) of predominantly silty and sandy soil in a warm temperate rainforest. The burrow was filled with water at the level of the creek but no connections to the creek were found (type 2 burrows). The largest male found was 17.8 mm carapace length. Mature females ranged from 17.6 to 20.4 mm carapace length (Horwitz 1990).

Threats [top]

Major Threat(s): This species is threatened by its restricted distribution coupled with the loss of riparian vegetation (Horwitz 1995). Loss of riparian strips results in elevated sedimentation and turbidity. At present, recreational fishing is allowed in Croajingolong National Park but it is not known whether harvesting of crayfish as food or bait is occurring. The potential range of this species also includes areas of private land grazed by cattle resulting in trampling, erosion and sedimentation of habitat (Van Praagh 2003a). Many species of Engaeus are particularly vulnerable to localized environmental disturbances (Williams 1990). Localized catastrophic events, such as an extended drought, fire or large sediment pulses could drastically effect populations of this species (Van Praagh 2003a). Broad scale habitat change and changes in weather, water and drainage patterns due to climate change could become a major issue in the future (N. Doran pers. comm. 2009).

Conservation Actions [top]

Conservation Actions: This species is classified as Threatened under the state of Victoria Flora and Fauna Guarantee Act 1988. The potential threat posed by elevated sedimentation and turbidity within Croajingolong National Park as a result of timber harvesting in adjacent state forest, is generally managed through the application of the Code of Forest Practices for Timber Production (NRE 1996). Degradation of native riparian vegetation along Victorian rivers and streams (SAC 1996) is listed as a potentially threatening process under the Flora and Fauna Guarantee Act 1988 (Van Praagh 2003a). The Thurra River is designated a Representative River, characteristic of the eastern Victorian dissected uplands and river plains and the catchment of the Benedore River is declared a "Scientific Reference Segment" under the State Environment Protection Policy -waters of East Gippsland (NRE 1996). These rivers occur within the potential range of the Mallacoota Burrowing Crayfish and may confer additional habitat protection for the species. The East Gippsland Forest Management Area Plan includes a specific conservation guideline for this species (Van Praagh 2003a).

Doran and Richards (1996) found that the primary consideration in the management of Engaeus species appears to be related to the level of available moisture, soil type and degree of disturbance to which they are subject.  Research into the current range and abundance of this species is required, with monitoring of the population trends and threats. Future research should focus on establishing a broad scale audit and monitoring program across this genus and other burrowing crayfish as they are likely to be very sensitive indicators of habitat and climate change (N. Doran pers. comm. 2009).

Citation: Doran, N. & Horwitz, P. 2010. Engaeus mallacoota. The IUCN Red List of Threatened Species 2010: e.T7736A12845459. . Downloaded on 20 September 2018.
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