Edwardsina tasmaniensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Insecta Diptera Blephariceridae

Scientific Name: Edwardsina tasmaniensis Tonnoir, 1924
Common Name(s):
English Tasmanian Torrent Midge

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2014
Date Assessed: 2013-01-25
Assessor(s): Gerlach, J.
Reviewer(s): Zwick, P.
This species was known originally from the type locality in the Cataract Gorge of the South Esk River, Launceston, northern Tasmania. The river is dammed at Trevallyn Dam near Launceston and used for the city's Hydro Electricity scheme. Although most of the water is dammed at Lake Trevallyn, some flows on into the Cataract Gorge where it becomes a tributary to the Tamar River, and the outflow from the power station also joins the Tamar River downstream of Launceston. It has not been located in Cataract Gorge since it was dammed in 1956, and was thought to be extinct in 1977. A single specimen was located in Dennison River in southwest Tasmania in 1976. This surviving population is within the Tasmanian Wilderness World Heritage Area. This population is not under immediate threat but is highly vulnerable to any changes in water flow, such as might be caused by changing rainfall resulting from climate change.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species was known originally from the type locality in the Cataract Gorge of the South Esk River, Launceston, northern Tasmania. This population is almost certainly extinct due to water extraction by a hydroelectric dam.  A small population survives in the Dennison River in southwest Tasmania.
Countries occurrence:
Australia (Tasmania)
Additional data:
Estimated area of occupancy (AOO) - km2:5
Number of Locations:2
Lower elevation limit (metres):100
Upper elevation limit (metres):200
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No data are available on the population but this species has only been observed in small numbers.
Current Population Trend:Unknown
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:UnknownPopulation severely fragmented:Unknown

Habitat and Ecology [top]

Habitat and Ecology:It is found in fast flowing small rivers at 100-200 m asl. Adults and larvae are predatory; larvae in streams and adults near water.
Systems:Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat:No

Threats [top]

Major Threat(s): The main population was threatened by the construction of the hydroelectric dam in 1956 which changed the water flow through the Cataract Gorge; this has probably resulted in the extinction of this population. The Dennison River population may be threatened by any factors that affect stream flow, climate change altering rainfall and hence hydrology may be a concern.

Conservation Actions [top]

Conservation Actions: The only recently recorded population (Dennison River) is within the Tasmanian Wilderness World Heritage Area

Citation: Gerlach, J. 2014. Edwardsina tasmaniensis. The IUCN Red List of Threatened Species 2014: e.T7037A21425779. . Downloaded on 23 May 2018.
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