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NT Naturalist - Number 29, Published July 2019

ISSN: 0155-4093

Editor: Richard Willan

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1. Understanding Australian tropical savanna: environmental history from a pollen perspective

AuthorsRowe, Cassandra; Brand, Michael; Hutley, Lindsay B.; Zwart, Costijn; Wurster, Christopher; Levchenko, Vlad; Bird, Michael
AbstractUnderstanding the long-term functioning of Australia’s tropical savannas is central to the management and conservation of these ecosystems. An environmental history of the Darwin region’s mesic savanna is presented from Girraween Lagoon, approx. 25 km southeast of Darwin, where pollen and charcoal analysis of a 5 metre sediment core provides a record spanning the previous 12,700 years. Results show the gradual development of permanent water at the site, surrounded by a dynamic landscape where changing climates and local people’s use of fire has shaped the vegetation from that of a savanna to an open forest.
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2. Effects of soil treatments on the establishment of Acacia and Eucalyptus following gravel extraction

AuthorsMadhu, K.C.; Bellairs, Sean M.
AbstractSources of construction materials such as gravel are sought near urban areas, including near Darwin, and these sites are required to be rehabilitated. However, few studies have investigated techniques to improve seedling establishment on gravel rehabilitation sites in northern Australia. This study investigated seedling establishment of the locally dominant tree species, Darwin Stringybark (Eucalyptus tetrodonta), Darwin Woollybutt (E. miniata) and the shrub, Western Salwood (Acacia lamprocarpa), on a gravel rehabilitation area near Howard Springs and in a shade house at Charles Darwin University, Darwin. The aim was to determine the effects of six treatments, including scarification, topsoil and application of leaf litter, and combinations of these treatments, on the emergence and survival of Acacia and Eucalyptus seedlings. Seedling establishment on the compacted gravel substrate was minimal, whereas application of litter or scarification of the gravel surface was found to increase seedling emergence and establishment. Seedling emergence was much greater in the shade house for all species (41%) than under field conditions (8%) suggesting that water stress was likely the major factor affecting survival in the field. Greater wind disturbance, seedling herbivory and erosion could have been additional factors. However, the application of topsoil had relatively little benefit for emergence, although later survival of E. miniata seedlings in topsoil was high. We suggest that altering or modifying the microsites of the gravel extraction areas by relatively easy and cost-effective methods such as scarification and application of litter can improve the seedling establishment of native woody species and help in rehabilitation of gravel extraction sites. Application of litter and scarification of the substrate are likely to enhance water availability for seedlings,
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3. Across the Barkly: fauna recovery from a gas pipeline trench

AuthorsSwan, Gerry; Wilson, Steve; Harvey, Christy
AbstractThis paper records the vertebrate fauna removed from a 481 km pipeline trench, which was the Northern Territory portion of a gas pipeline running from Tennant Creek, Northern Territory, to Mt Isa, Queensland. The project was conducted in two stages; the first from August to November 2017 and the second from May to July 2018. All the open section of the trench was checked daily during the entire construction of the pipeline, despite resourcing problems during the first stage. There were 14,613 animals retrieved comprising 113 species, with the majority (12,513 animals) recorded during the first stage. We compare our results with three previously published studies and discuss the problem of fauna mortality during pipeline construction.
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4. An observation of excavating behaviour by a Black-headed Python (Aspidites melanocephalus) in the wild

AuthorsSwan, Gerry; Harvey, Christy
AbstractThe Black-headed Python (Aspidites melanocephalus) and the Woma (Aspidites ramsayi) have both been reported as carrying out burrowing or excavating behaviour. These reports have been based mainly on observations of captive individuals, with the only observations of specimens in the wild being those of Bruton (2013) on Womas. Here we report on a Black-headed Python scooping out sand with its head and fore-body to create a depression in the wild.
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5. An assessment of thermal preference of two species of Knob-tailed Geckos, Nephrurus levis and N. laevissimus, at Uluru Kata-Tjuta National Park

AuthorsHays, Brenton J.; Bidwell,Joseph R.; Dittmer, Drew E.
AbstractNocturnal lizards are often active at temperatures that are sub-optimal for physiological functioning, a phenomenon that has been referred to as the ‘nocturnal paradox’. The purpose of this study was to investigate the general habitat and thermal preference of two species of nocturnal gecko in the genus Nephrurus with a focus on differences between preferred body temperatures determined under laboratory conditions and those measured in animals at the time of field collection. The Smooth Knob-tailed gecko (Nephrurus levis) and the Pale Knob-tailed Gecko (N. laevissimus) inhabit the desert environment of Uluru Kata-Tjuta National Park in the Northern Territory of Australia. Habitat preferences were determined by documenting capture locations for these species while thermal preferences were determined using laboratory-based thermal gradients. Analysis of habitat use demonstrated a significant difference in habitat preference between the two species. Nephrurus levis was most often in Spinifex sandplain and mulga shrubland and N. laevissimus was most often found around sand dune habitats. Fieldactive body temperatures of both species ranged from 14.5 °C to 32.2 °C and were significantly correlated with air and ground temperature at the time of capture. The thermal preference (Tpref) of N. levis (mean day Tpref mid = 29.1 °C and mean night Tpref 24 = 28.2 °C, n = 19) and N. laevissimus (mean day Tpref mid = 29.5 °C and mean night Tpref 24 = 27.8 °C, n = 27) were not significantly different, although both species exhibited significantly higher daytime and night-time preferred body temperatures than body temperatures observed in the field. Body size did not affect thermal preference for either species. As such, the thermal preferences of these species support the concept of the nocturnal paradox. Additionally, it has been suggested that the characteristic swollen tail tip displayed by all Nephrurus species may play a role in assessing the thermal environment. While not investigated extensively here, combined data for both species demonstrated that individuals oriented their tail toward the heat source in thermal gradients significantly more than expected if orientation were random.
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6. An observation of Burton’s Legless Lizard (Lialis burtonis) in a tropical mangrove forest

AuthorsBourke, Adam. J.
AbstractA Burton’s Legless Lizard (Lialis burtonis) was observed within the Rhizophora zone of a tropical mangrove forest in the Top End of northern Australia in November 2018. To the author’s knowledge, this is the first record of L. burtonis within a tidal forest. Although this lizard occurs in virtually all habitat types and is capable of comparatively longdistance movements, its presence in mangrove forests is presumably a rare occurrence.
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7. Sex determination in-ovo as a population management tool for the Southern Cassowary and Coastal Emu

AuthorsHall,, Clancy A.; Potvin,, Dominique A.
AbstractAustralia has lost two species and one subspecies of ratite due to historical persecution and anthropogenic changes to their habitats. Two additional ratites, the Southern Cassowary (Casuarius casuarius johnsonii) and Coastal Emu (Dromaius novaehollandiae), are following this trajectory and will require human intervention to prevent further population decline or extinction. Advanced reproductive technologies offer promising avenues for the management of genetic and demographic diversity, both in-situ and ex-situ. Here, we review two important techniques and their efficacy in the conservation management of Australian ratites. The first is the sexing of an embryo in-ovo. This technique is central to developing technologies, however, is presently problematic in species producing thick and heavily pigmented eggs (i.e. Cassowary and Emu). Developments including the reduction of the shell membrane may promote light refraction and thus render the technique able to be used safely with developing embryos of Australian ratites. The supplementation of natural hormone during early embryonic development is another tool for sex regulation in ratite embryos. This was previously trialled in the Ostrich to influence a preferred gonadal sex, however, it will be trialled in the Emu and Cassowary for the first time. The use of these advanced reproductive technologies will complement current conservation efforts for Australian ratites, and facilitate the establishment and maintenance of robust captive populations.
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8. Do freshwater mussels exist on the Tiwi Islands?

AuthorsWillan, Richard C.; Jones, Hugh A.
AbstractExhaustive searches through collections and literature indicates that apparently no member of the freshwater mussel family Hyriidae exists on the Tiwi Islands, off the central Northern Territory coastline. Nor apparently does any hyriid exist on Cobourg Peninsula on the adjacent mainland of western Arnhem Land. These absences are despite seemingly suitable habitats being present on these large nearshore islands and landmass at the present time. Other hyriids do exist on nearshore islands in northern Australia and elsewhere in Australasia. The reasons for these absences are discussed briefly, with the most likely being a more arid climate during the Last Glacial Maximum drying out the streams and wetlands in the region.
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9. Incursion of the bivalve Potamocorbula faba into northern Australia: a record from a Holocene archaeological site in Kakadu National Park

AuthorsWoo, Katherine G.P., Willan, Richard C.
AbstractThis paper reports the discovery of the estuarine bivalve species Potamocorbula faba at the archaeological site Ngarradj Warde Djobkeng in Kakadu National Park, Northern Territory. Although presently widespread and abundant in southeastern Asia, this species is not known to be living anywhere in northern Australia today, and neither is it known as a pre-Holocene fossil. Therefore, it must have made a temporary incursion into western Arnhem Land between 3300 and 3600 years ago.
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10. Catch, discard and bycatch rates in the Western Gulf of Carpentaria Mud Crab Fishery: summary for 2017 and 2018

AuthorsGrubert, Mark A.
AbstractCatch, discard and bycatch rates in wire mesh mud crab pots set in two regions of the Western Gulf of Carpentaria are summarised for 47 fishery observer trips undertaken aboard commercial crab fishing vessels in the months of April and May in 2017 and 2018. Catch rates of the Giant Mud Crab (Scylla serrata) in both regions and both years were relatively high (i.e. 0.74–1.02 kg/pot-lift), as were discard rates (i.e. 59–69% of individual Mud Crabs captured). Between 33% and 57% of all discarded crabs had attained the minimum legal size, but were released on the basis that they were ‘commercially unsuitable’, having a soft shell, low vigour and low meat content. A total of 88 individuals from 12 different taxa were recorded as bycatch from 4337 potlifts. Catfishes (Arius spp.) were by far the most numerous bycatch, accounting for 64% of all individuals. There were no interactions between mud crab pots and threatened, endangered or protected species during any observer trips. The low incidence of bycatch in wire mesh mud crab pots is consistent with previous observations on the use of this type of gear both locally and interstate.
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11. A record of fish predation by the mangrove crab Epixanthus dentatus (Brachyura: Oziidae)

Authors, Adam. J.
AbstractA case of predation by the oziid crab Epixanthus dentatus on the gobiid fish Acentrogobius viridipunctatus within a mangrove forest in Darwin Harbour, Australia, is reported here. The observation was made after the moment of prey capture, however both the patterns of injury and freshness of the carcass indicate the goby had been ambushed live during the previous ebb tide. This is the first record of E. dentatus predating fish and increases the known diet of the species.
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12. First record of the Grass Cross Spider (Argiope catenulata) of the family Araneidae in Australia

AuthorsBrown, Graham R.; Henderson, Caitlin L.
AbstractThe Grass Cross Spider, Argiope catenulata (Doleschall 1859), is newly recorded from Australia based on collections made in early 2019 from three dams in the vicinity of Darwin, Northern Territory. Both sexes are illustrated, as is the egg sac and habitat. Preliminary discussion is given about its introduction and dispersal.
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13. Book Review: Dinosaurs – How They Lived and Evolved

AuthorsWright, Neil R.
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14. Book Review: Australian Birds of Prey in Flight

AuthorsRiddell, William
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15. Book Review: A Field Guide to the Freshwater Fishes of the Kimberley

AuthorsBrown, Graham R.
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