The Giant Gippsland Earthworm, Megascolides australis, population at Loch Hill, South Gippsland : distribution and preliminary biological and soil studies.
Museum Victoria Science Reports: No. 2 pp 1-10 (2002)
Abstract
A preliminary study of the distribution, soils and biology of the Giant Gippsland Earthworm at Loch Hill was conducted between September and November 2001. This population occurs in the vicinity of proposed roadworks for the South Gippsland Highway between Loch and Bena.
The earthworm population at Loch Hill was found to have a relatively restricted distribution, confined to an area of approximately 2500m2 , extending south-east of the tree fern, across the face of the hill to just past the seepage channel. The population extends downslope to just above the tributary of Allsop Creek but is absent from the valley floor. Soil investigations reveal that this area corresponds to a section of the hill with very pronounced terracettes, indicating that the land surface is wetter than the surrounding area.
Worms appeared to be widespread within their area of distribution. Six quadrats were examined for worm density from which a total of 23 worms were recorded. Worm density within this area was very high ranging from 4.1 to 17.9 worms per m3 with an average of 8.5 worms per m3 calculated. This indicates a very high density of worms at Loch Hill.
A range of age classes were found with adult, subadult and juvenile worms recorded. The largest worm found weighed 250g. No breeding adults were found despite sampling occurring within the known breeding season.
If road works proceed in the area occupied by the Giant Gippsland Earthworm population at Loch Hill, the entire earthworm habitat at the site would be lost. The impacts of road works at the site on the species are discussed and include directly killing individuals and injury of earthworms during soil excavation, compacting the soil and altering the soil habitat in particular drainage and moisture regimes at the site.
The only mitigation measure available is to attempt to ‘rescue’ the existing population before and during roadworks and endeavour to protect or restore any earthworm habitat near by that may escape the direct impacts of the roadworks. Research opportunities resulting from this situation and their benefits to the long term survival and conservation of this species are discussed.
Citation
Van Praagh, B.D., Hinkley, S.D. and Sargeant, I. J. 2002. The Giant Gippsland Earthworm, Megascolides australis, population at Loch Hill, South Gippsland : distribution and preliminary biological and soil studies. Museum Victoria Science Reports 2: 1–10.