Mt Donna Buang Wingless Stonefly (Riekoperla darlingtoni)

Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Scientific name, common name (where appropriate), major taxon group

Riekoperla darlingtoni  (Mt Donna Buang Wingless Stonefly)

2. National Context

The Mt Donna Buang Wingless Stonefly is known to occur in the area of Mount Donna Buang, in the Yarra Valley, near Warburton, in the Central Highlands of Victoria. It has been found to occur primarily within one kilometre of the summit of Mount Donna Buang, although in 1993, a mature stonefly of this species was found three kilometres northeast of the summit and in 1999 a nymph was located in the same area. Very little is known about population numbers of the species. This stonefly has been found in and along the edges of temporary streams with cool, clear water. The immature stage is aquatic and as the adults are flightless, the species is tied closely to riparian habitats.

The species is not listed under the EPBC Act, however, it is listed as vulnerable under the Victorian Flora and Fauna Guarantee Act 1988. Mount Donna Buang is listed on the Register of the National Estate in recognition of the presence of the Mt Donna Buang Wingless Stonefly.

3. How judged by TSSC in relation to the EPBC Act criteria

TSSC judges the species not to be eligible for listing under the EPBC Act.  The justification against the criteria is as follows:

Criterion 1 - Decline in numbers

There is no evidence available against this criterion.

Therefore, the species is not eligible for listing under this criterion.

Criterion 2 - Geographic distribution

From what is currently known, the Mt Donna Buang Wingless Stonefly has a very restricted geographic distribution, with a total estimated area of occupancy of just 2-4km2. The species has only been found between 1000-1200m above sea level, at two localities. The first of these is situated within 1km of the summit of Mount Donna Buang and includes a number of separate sites. This location is considered to have the largest number of individuals and to be the stronghold of the population. The second location, which was only discovered in 1993, is considered to have a much smaller population, with just one mature individual and one nymph recorded at the site to date. This location is situated three kilometres northeast of the summit of Mount Donna Buang. The species is considered to have poor dispersal abilities as it is wingless. Both locations of the species are located within the Yarra Ranges National Park.

It appears that comprehensive surveys have been carried out for this species in suitable habitat within Victoria and New South Wales and that the species is restricted to the population at Mount Donna Buang.

Although the location within 1km of the summit is situated within the Yarra Ranges National Park, the proximity of the park to Melbourne makes the park a popular tourist attraction. The park is a particularly popular tourist attraction in winter, when snow falls on the summit. Mount Donna Buang receives approximately 20 000 visitors per annum. To cope with this demand, a range of visitor facilities has been installed on the summit of Mount Donna Buang since the 1960s, including car parks, toilets and picnic facilities. Some of these have been placed adjacent to the streams that constitute potential stonefly habitat although recent upgrades of the facilities have been restricted to the sites of the old facilities. The trampling of vegetation close to streams and the pollution of the streams through run-off from car parks are two examples of threats that may lead to decline in the population of the Mt Donna Buang Wingless Stonefly at this primary location. Other potential threats include the plant disease Myrtle Wilt, that affects the Nothofagus species understorey favoured by the Mt Donna Buang Wingless Stonefly, wildfire, and increased sedimentation and turbidity of the streams, altered drainage patterns and soil compaction levels as a result of the development. Although these threats may contribute to a future decline in the species' area of occupancy, extent of occurrence, quality of habitat, number of locations and number of mature individuals there is no clear evidence of direct threat to the species. In addition, there is active management including the closure of adjacent walking trails and revegetation of a former carpark at the summit of Mount Donna Buang designed to mitigate any potential threats to the Stonefly.

The location three kilometres from the summit of Mount Donna Buang is closed to public access and is administered by Melbourne Water as it forms part of the catchment for drinking water harvested for Melbourne. Potential threats to the population at this location include the plant disease Myrtle Wilt, wildfire, and increased sedimentation and turbidity of streams.

From what is currently known, the Mt Donna Buang Wingless Stonefly is very restricted in geographic distribution and area of occupancy. The location closer to the summit, which forms the stronghold for the species, is potentially threatened by a variety of factors, primarily related to past development for tourism but none appear to constitute a direct threat to the species. The location three kilometres from the summit, which appears to have a low number of individuals, is threatened by plant disease and changes in water quality, however, similarly, there are no known direct threats to the species at this site.

Therefore, the species is not eligible for listing under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

There is no evidence available against this criterion.

Therefore, the species is not eligible for listing under this criterion.

Criterion 4 - Population size

There is no evidence available against this criterion.

Therefore, the species is not eligible for listing under this criterion.

Criterion 5 - Probability of extinction in the wild

There is no evidence available against this criterion.

Therefore, the species is not eligible for listing under this criterion.

4. Conclusion

There is little quantitative data available on the population numbers of the Mt Donna Buang Wingless Stonefly, however, surveys of suitable habitat to date indicate that the species has a very restricted distribution, occurring in two locations on Mount Donna Buang and an estimated area of occupancy of 2-4km2. Despite this restricted distribution, there do not appear to be any direct threats to the species' survival and there is active management addressing development and recreational pressures in the area.

The species is not eligible for listing under the EPBC Act.

5. Recommendation

TSSC recommends that the species Riekoperla darlingtoni (Mt Donna Buang Wingless Stonefly) is not eligible for inclusion in the list referred to in section 178 of the EPBC Act.