Wangamaty (Lower Daly River) Management Plan

ECOZ Environmental Services, (2004?)
The Wangamaty Landcare Group (WLG) initiated this study to investigate the adoption of an integrated management plan for the Lower Daly region. Recommendations include:

• implemention of a 5 year Weed Action Plan
• development of an up to date legislative framework and planning instrument to identify and rectify gaps in dealing with resource management issues
• recommendations for managing riparian zones, rainforest and wetlands
• identification of monitoring needs
• professional development with the WLG
• water allocation plan and natural resource management strategy
• pest animal study
• strategic fire management plan

Copy available for loan: NRETAS and DPI Library

Thermal models of TSD under laboratory and field conditions

A. Georges, S. Doody, K. Beggs and J. E. Young
Smithsonian Institute,

Recent studies have demonstrated a remarkable range of interactions between environmental conditions and developmental attributes and outcomes in reptilian eggs. If we look beyond the practical application of these models to ecological implications, the models discussed in this paper yield important insights. They explain why mixed sex ratios occur in more nests than would be expected from the very narrow pivotal temperature range of many species, even in the absence of gradients in mean temperature with depth. The models provide us with more scope for exploring how reptiles with TSD (Temperature-dependent sex determination) might respond to climatic change, latitudinal variation in climate, or other disturbances to the incubation environment, because they identify a range of additional parameters that shallow-nesting species can manipulate in order to compensate for climatic change or variation with latitude.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Family Carettochelyidae

A. Georges and J. Wombey
Australian Biological Resources Study, DASETT,

Pivotal range and thermosensitive period of the pig-nosed turtle, Carettochelys insculpta (Testudines: Carettochelydidae), from northern Australia

J. E. Young, A. Georges, J. S. Doody, P. B. West and R. L. Alderman 82, 1251-1257,

Understanding temperature-dependent sex determination in nature often depends on knowledge of species specific attributes that are integrated into the relationship between temperature and sex. We determined two such attributes for the pig-nosed turtle, Carettochelys insculpta Ramsay, 1886, in tropical Australia: the pivotal range in temperature that separates the male-producing domain from the female-producing domain, and the thermosensitive period during which the embryonic sex is influenced by temperature. The pivotal range for C. insculpta was very narrow, spanning only about 1 °C, and was centred on 32 °C, which is high but consistent with temperatures reported for other tropical species. The thermosensitive period spanned developmental stages 17–21 for temperature influence in the direction of maleness and 18–21 for temperature influence in the direction of femaleness. This period is slightly narrower than that for other reptile species but broadly consistent with the middle third of incubation.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Resource Partitioning among the freshwater turtles of the Daly River, Northern Territory.

M. Welsh
University of Canberra, 9/8/99

The primary aim of this study was to examine food and microhabitat partitioning among the freshwater turtles of the Daly River. Natural processes and species interactions were discussed to explain patterns of local species composition and overall species richness, and in addition, findings were discussed in regards to freshwater turtle conservation.

The thesis provides possible explanations for the high species richness in turtles in the Daly River and also information on the conservation of the turtles

Carettochelys insculpta (pig-nosed turtle). Ectoparasites

R. A. Saumure and J. S. Doody
Herpetological Review, 31, 4, 237-238

Leeches were found parasitizing pig-nosed turtles captured in the Daly River at Oolloo crossing, Northern Territory, Australia, on October 26, 1996. This leech species, Placobdelloides bancrofti, has not been collected since the original description from the host turtle Emydura krefftii in the Burnett River, Queensland, Australia. Here the authors document a new host record and range extension of P. bancrofti, and the first hirudinean parasite for Carettochelys insculpta, the pig-nosed turtle.
http://search.ebscohost.com/login.aspx?direct=true&db=fzh&AN=231801999993043&site=ehost-live

Diet of two freshwater turtles, Chelodina rugosa and Elseya dentata (Testudines: Chelidae) from the wet-dry tropics of northern Australia

R. Kennett and O. Tory
Copeia, 1996, 2, 409-419,

Ecology of two species of freshwater turtle, Chelodina rugosa and Elseya dentata, from the wet-dry tropics of northern Australia

R. Kennett
University of Queensland

The ecology of the pig nosed turtle, Carettochelys insculpta, in northern Australia

L. J. Heaphy
University of New South Wales, Sydney

Conservation biology of the pig-nosed turtle, Carettochelys insculpta

A. Georges and M. Rose
Chelonian Conservation and Biology, 1, 1, 1-12,

Carettochelys insculpta is the sole surviving member of the Carettochelyidae, a family of turtles widely distributed during the Territory. It is restricted to the southern rivers of New Guinea and the major rivers of the Northern Territory in Australia. Carettochelys is a distinctive geographic and taxonomic relict and, although locally abundant, it is rare in the sense of being geographically restricted. In Australia, feral water buffalo pose a major threat through the trampling of nesting banks and widespread destruction of the riparian vegetation upon which the turtles depend. Other potential pressures include aggressive pastoral and agricultural practices that push the land beyond capacity in the important catchments, with resulting erosion and siltation of water courses. Mining activity in sensitive areas, such as Kakadu National Park, may also pose a threat unless strict controls are applied on containment of mine waste, fishing activities of the mine staff, draw-down of the water table, and routes taken in the transport of chemicals used for extraction of minerals.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Dry season distribution and ecology of Carrettochelys insculpta (Chelonia: Carrettochelydidae) in Kakadu National Park, northern Australia.

A. Georges and R. Kennett
Australian Wildlife Research, 16, 323-335,
Carrettochelys insculpta is widely distributed (though not necessarily abundant) in Kakadu National Park during the dry season, occupying permanent billabongs from the black-soil plains to the base of the escarpment. High population densities were found in the upper reaches of the South Alligator drainage (33.8 turtles ha-1; 227.4 kg ha-1) and are interpreted as dry-season concentrations of turtles that would occupy a much wider range in the wet season. C, insculpta nest in clean, fine sand adjacent to water from mid July to early November. About 15 hard-shelled spherical eggs were laid in a shallow chamber (maximum depth 18-21 cm) between 1.0 and 3.7m from the water, with the height above water ranging from 0.4 to 0.7m. The nests suffered heavy predation from the varanid lizards. The turtles are general omnivores that draw upon a wide variety of food, including algae, aquatic macrophytes, fruits, seeds and leaves of riparian vegetation, aquatic macroinvertebrates, and carrion. Its catholic tastes provide great scope for opportunism, and its diet varies greatly in accordance with the foods available from locality to locality. The ecological basis for the restricted global distribution of C.insculpta is unclear.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

A note on Carettochelys insculpta (Testudinata: Carettochelydidae) from northern Australia

A. Georges, D. Choquenot, A. J. Coventry and P. Wellings
Northern Territory Naturalist, 11, 8-11

The Australian Pig-nosed turtle (Carrettochelys insculpta)

A. Georges, J. S. Doody, J. Young and J. Cann
CRC for Freshwater Ecology, University of Canberra,
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Modelling Development of Reptile Embryos under Fluctuating Temperature Regimes

A. Georges, K. Beggs, J. E. Young and J. S. Doody
Physiological and Biochemical Zoology, 78, 1, 18-30,
An increase in temperature, within bounds, will accelerate development of reptile embryos, and morphogenesis can be normal over a range of temperatures despite those varying rates of development. Less well understood is the form of the relationship that best describes variation in developmental rate with temperature. In this article, we apply a linear degree.hour model, an empirical curvilinear model, a biophysical model, and a polynomial model to data on rates of embryonic development and temperature in the pig-nosed turtle Carettochelys insculpta from northern Australia. The curvilinear models, which have been applied with success to development of insects, describe the embryonic development of turtles well.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Thermal characteristics and sex determination in field nests of the pig-nosed turtle, Carrettochelys insculpta (Chelonia: Carettochelydidae) from nort

A. Georges
Australian Journal of Zoology, 40, 5, 511-521,
Carettochelys insculpta lays its eggs in shallow nests constructed in clean fine sand adjacent to water. Six nests had the following thermal characteristics: (1) core temperatures ranging from 26.1 to 33.7C early in September, from 30.0 to 38.7C early in October and from 28.4 to 36.8C early in November; (2) a pronounced daily cycle in core temperatures of up to 6.4C in amplitude, with the minimum occurring after sunrise in mid-morning and the maximum occurring in the evening; (3) a difference in the temperatures experienced by the top and bottom eggs in a single nest of up to 3.5C at any one time. Nest heating and the maximum temperatures achieved were principally driven by solar irradiation, not ambient air temperatures. Hot nests produced females exclusively, nest intermediate in temperature produced a mixture of sexes, and the sole cool nest produced males exclusively. In nests that produced both sexes, males emerged from the deepest coolest eggs whereas females emerged from the shallowest eggs. http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Female turtles from hot nests: Is is the amount of development or duration of incubation at high temperature that matters?

A. Georges
Oecologia (Berlin), 81, 323-328,
Mean daily temperature in natural nests of freshwater turtles with temperature-dependent sex determination is known to be a poor predictor of hatchling sex ratios when nest temperatures fluctuate. To account for this, a model was developed on the assumption that females will emerge from eggs when more than half of embryonic development occurs above the threshold temperature for sex determination rather than from eggs that spend more than half their time above the threshold. The model is consistent with previously published data and in particular explains the phenomenon whereby the mean temperature that best distinguishes between male and female nests decreases with increasing variability in nest temperature.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

The Territory's intriguing turtles

S. Doody
Australian Geographic, 58, 22, 04
Presents information on pig-nosed turtles in Daly River in the Top End of the Northern Territory in Australia. Why turtles form bare-sand aggregations; Background on the discovery of pig-nosed turtles; Biology of pig-nosed turtles.

http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=3560767&site=ehost-live

Monitoring programme for the pig-nosed turtle

S. Doody
University of Canberra,
To monitor the distribution and abundance of the pig-nosed turtle in the Daly River.

Sex Differences in Activity and Movements in the Pig-Nosed Turtle, Carettochelys insculpta, in the Wet-Dry Tropics of Australia

J. S. Doody, J. E. Young and A. Georges
Copeia, 2002, 93-103,
Dry season movement patterns, home ranges, and activity was studied in a population of pig-nosed turtles (Carettochelys insculpta) in the wet-dry tropics of northern Australia. Compared to other turtles inhabiting lotic habitats, C. insculpta occupied considerably larger home ranges, covering up to 10 km of river. Of previously published factors influencing home range size, low productivity of the (micro) habitat may best explain the extensive home ranges in C. insculpta. Patchiness and low nutrient value of the chief food (aquatic vegetation) of C. insculpta may force turtles to cover large expanses of river to acquire sufficient energy for growth and reproduction.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G

Beach Selection in Nesting Pig-Nosed Turtles, Carettochelys insculpta

J. S. Doody, P. West and A. Georges
Journal of Herpetology, 37, 1, 178-182,
We investigated beach selection of nesting Pig-Nosed Turtles (Carettochelys insculpta) along a 63-km stretch of river for two years. We found 221 nests on 82 nesting beaches and identified 171 potential nesting beaches based on previously published criteria. Beaches with nests had a greater substrate moisture content and corresponding higher cohesive sand line (hereafter CSL) than beaches without nests. Beaches with nests also had a higher CSL than beaches with only crawls. Beach temperatures increased with a seasonal increase in air temperatures and were influenced by aspect and total angle of solar exposure. Turtles did not select beaches that were hotter or cooler, on average, than what was available, indicating that turtles were not manipulating offspring sex through choice of nesting beach.
http://aerg.canberra.edu.au/cgi-bin/pubs_archive.cgi?target=G