Emydura macquarii signata
Summary information
Distribution: known from the Bellinger River catchment between Winch Flat and the tidal zone, north coast of New South Wales (Spencer et al. 2007).
Habit and habitat: found in long shallow waterholes (less than 3 metres deep) with a rocky substrate and vegetation, especially Hydrilla verticillata, in permanently flowing rivers and large creeks of the Bellinger River catchment.
Activity period: unknown; presumably late spring and through summer. Active morning and afternoon, and presumably throughout part of the night.
Survey methods
The species has been recorded while snorkelling, using cathedral traps and by dip netting from a boat at night. While most species of Emydura readily enter cage traps, this technique is at best likely to only be of limited success.
Snorkelling tends be more successful in clearer, upstream sections of river. Snorkelling should consist of either swimming along the surface or diving. Extra time should be spent searching around logs and submerged snags, because the turtle is harder to detect in these places.
Where poorer visibility and long waterholes exclude snorkelling, turtles can be captured using long-handled dip nets off a small boat. This has been successful at night-time in the deeper waterholes around Bellingen. Portable spotlights should be used to locate turtles.
Baited cathedral traps placed next to the riverbank in the vicinity of good microhabitat (for example, logs, overhanging banks, aquatic vegetation) can also be used to capture turtles. Traps should be supported by tying the upper parts of the traps to overhanging trees. Traps can be baited with sardines, with part of the bait held loosely in nylon mesh bags and available for the turtles to eat, and part of the bait held in perforated cans. Traps should be checked at intervals of 4–10 hours and re-baited after approximately 24 hours. Traps can be left in place for 24–48 hours.
Similar species in range: The Murray turtle Emydura macquarii is broadly sympatric with Georges' turtle Elseya georgesi in the Bellinger River. The head and neck of the Murray turtle is grey with a single yellow stripe running from the rear of the jaw, and pale yellow crescent bordering the underside of the jaw. The dorsal and lateral side of the head is usually smooth. Georges' turtle similarly has a yellow stripe running from the rear of the jaw, but also has a bold yellow patch on the underside of the throat and a distinctive horny casque over the top of the head and predominant low rounded tubercules on the side of the head typical of species of Elseya.
Potential records of the Murray turtle from the Bellinger River catchment and smaller rivers to the north and south should be supported by a good quality colour photograph and where possible a tissue sample for genetic analysis. Photo vouchers should be forwarded to the state fauna authority and appropriate state museum for positive identification and databasing of the record, and tissue samples sent to the state museum.
Note: The taxonomy of Australian freshwater turtles is still being refined, particularly the status of morphologically distinctive but genetically similar (Georges & Adams 1992) populations of Emydura from the coastal and inland rivers systems of the east coast. Cann (1998) recognised a number of populations of Emydura from the eastern flowing drainages of NSW as distinct subspecies of the Murray turtle, but refrained from naming the Bellinger River population pending acquisition of further specimens and data. McCord and colleagues (2003) recognised a further two subspecies of Murray turtle from Queensland.
More recent work (Georges et al. 2007) suggests that the Bellinger River emydura is within the range of normal genetic and morphological variation for the Murray turtle. The subspecies has recently been removed from the NSW Threatened Species Conservation Act 1995 on the basis that “turtles of this catchment are now thought to be part of a much larger population extending over north-east NSW, and current knowledge indicates that the total number of mature individuals of the taxon is not low. There is no evidence of a moderately large reduction in the taxon, nor is it moderately restricted” (DECCW 2009).
Key references for Emydura macquarii signata
Blamires, S.J. & Thompson, M.B., 2003. Survey of Bellinger River Turtles, Elseya georgesi and Emydura macquarii ssp.: an assessment of potential impacts of foxes. Internal Report: University of Sydney.
Blamires, S.J., Spencer, R. J., King, P. & Thompson, M.B. 2005. Population parameters and life-table analysis of two coexisting freshwater turtles: are the Bellinger River turtle populations threatened? Wildlife Research 32: 339-347.
Cann, J., 1998. Australian Freshwater Turtles. Beumont Publishing Pty Ltd, Singapore.
Cogger, H.G., Cameron, E.E., Sadlier, R.A. & Eggler, P. 1993. The action plan for Australian reptiles. Australian Nature Conservation Agency, Canberra. 254 pp.
DECCW. 2009. Emydura macquarii (Gray, 1830) – species delisting. Final determination of the NSW Scientific Committee, Department of the Environment, Climate Change and Water. Available from: www.environment.nsw.gov.au/determinations/emyduramacquariiFD.htm. Accessed 2010-01-18.
Georges, A. & Adams, A., 1992. A phylogeny for Australian chelid Turtles based on allozyme electrophoresis. Australian Journal of Zoology 40: 453-476.
Georges, A., Walsh, R., Spencer, R.J., Welsh, M. & Shaffer, H.B. 2007. The Bellinger Emydura. Conserve or Eradicate? Report to NSW National Parks and Wildlife Service, Sydney, by the Institute for Applied Ecology, University of Canberra. July 2007.
McCord, W.P., Cann, J. & Joseph-Ouni, M. 2003. A taxonomic assessment of Emydura (Testudines: Chelidae) with descriptions of new subspecies from Queensland, Australia. Reptilia 27(60): 59-63.
Spencer, R.J. & Thompson, M.B. 2001. The ecology and status of Emydura macquarii and Elseya georgesi in the Bellinger River. Report to the NSW Parks and Wildlife Service. Sydney: University of Sydney.
Spencer, R.J., Georges, A. & Welsh, M. 2007. The Bellinger Emydura: Ecology, population status and management. Unpublished report by Institute for Applied Ecology, University of Canberra, for NSW NPWS.
Dostları ilə paylaş: |
