Larval nurseryfish, Kurtus gulliveri (Perciformes : Kurtidae), in the Adelaide River of the Northern Territory: their season, fellow travellers and unusual rib anatomy

2016 ◽  
Vol 64 (4) ◽  
pp. 262 ◽  
Author(s):  
Tim M. Berra ◽  
Dion Wedd ◽  
You He

This study was undertaken to determine the spawning season of the nurseryfish, a species with a unique method of parental care found only in northern Australia and southern New Guinea. Monthly samplings with an ichthyoplankton net at the same locality in the Adelaide River over multiple years yielded no larval nurseryfish in February, March, April and May. Larvae first appeared in June and were collected each month until January. From this we conclude that the nurseryfish spawning season in the Adelaide River is June–January. Twelve other larval fish species from 10 families were collected in the plankton tows with nurseryfish. Larval nurseryfish are readily identified and separated from other larval fishes by their peculiar rib anatomy, an important diagnostic character of Kurtus. The development of the unusual rib anatomy is examined with three-dimensional micro-computerised tomography scans of 12–21-mm standard length (SL) specimens. The bony protection of the swim bladder formed by the ribs is visible in the smallest postflexion specimens examined and is essentially complete by 19 mm SL. These ecological and anatomical observations add another pixel to the big picture of nurseryfish life history.


2016 ◽  
Vol 13 (116) ◽  
pp. 20160068 ◽  
Author(s):  
Gen Li ◽  
Ulrike K. Müller ◽  
Johan L. van Leeuwen ◽  
Hao Liu

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.



2017 ◽  
Vol 284 (1852) ◽  
pp. 20170359 ◽  
Author(s):  
Arjun Nair ◽  
Christy Nguyen ◽  
Matthew J. McHenry

An escape response is a rapid manoeuvre used by prey to evade predators. Performing this manoeuvre at greater speed, in a favourable direction, or from a longer distance have been hypothesized to enhance the survival of prey, but these ideas are difficult to test experimentally. We examined how prey survival depends on escape kinematics through a novel combination of experimentation and mathematical modelling. This approach focused on zebrafish ( Danio rerio ) larvae under predation by adults and juveniles of the same species. High-speed three-dimensional kinematics were used to track the body position of prey and predator and to determine the probability of behavioural actions by both fish. These measurements provided the basis for an agent-based probabilistic model that simulated the trajectories of the animals. Predictions of survivorship by this model were found by Monte Carlo simulations to agree with our observations and we examined how these predictions varied by changing individual model parameters. Contrary to expectation, we found that survival may not be improved by increasing the speed or altering the direction of the escape. Rather, zebrafish larvae operate with sufficiently high locomotor performance due to the relatively slow approach and limited range of suction feeding by fish predators. We did find that survival was enhanced when prey responded from a greater distance. This is an ability that depends on the capacity of the visual and lateral line systems to detect a looming threat. Therefore, performance in sensing, and not locomotion, is decisive for improving the survival of larval fish prey. These results offer a framework for understanding the evolution of predator–prey strategy that may inform prey survival in a broad diversity of animals.



2020 ◽  
Vol 64 (4) ◽  
pp. 467-477
Author(s):  
Garrard Cole ◽  
Tony Waldron ◽  
Susan Shelmerdine ◽  
Ciaran Hutchinson ◽  
Kieran McHugh ◽  
...  

AbstractWe provide a brief account of the life and work of Jules Parrot, a significant figure in French paediatrics, about whom almost nothing has been written. We focus on his work relating to congenital syphilis, specifically reporting on the examination of a collection of bones taken at autopsy from children with congenital syphilis. The collection of bones was brought to London in 1879 by Parrot to illustrate a talk that he gave before the Pathological Society of London. Subsequently, it travelled a circuitous route to the Royal Free Hospital pathology collection, where it remained until we (GC and TW) ‘discovered’ it. The bones represent the largest assemblage of material from cases of congenital syphilis in the UK and they are important as they clearly demonstrate the skeletal lesions associated with congenital syphilis and are now irreplaceable. The bones have been identified to anatomical element and have come from a minimum of eight children, both foetuses and neonates covering the period 30–50 weeks post-conception. Radiological and micro computerised tomography examinations were carried out and three-dimensional models printed at twice life size. The models are durable and can be handled with impunity by students and others wishing to familiarise themselves with the skeletal changes shown.



1986 ◽  
Vol 20 (1) ◽  
pp. 70-76 ◽  
Author(s):  
John Cawte

The kava bowl, a traditional feature of Pacific Island societies, has been adopted and adapted by a number of Aboriginal (Yolngu) communities of northern Australia, where it was introduced in the hope that it would challenge alcohol. This paper reports a study of its usage at Elcho Island, Northern Territory. At the high level of intake in this community, medical effects hitherto unreported are being observed. Some, such as a condition of detachment, reminiscent of the archetypal ‘blissful indolence’ of the lotus-eaters of Greek tradition as limned by the poet Homer, are obvious to the lay observer. Other effects are apparently advantageous for the management of alcohol abuse and some forms of psychosis. A surprising effect is the occurrence of a pellagrinous reaction. These observations indicate that further studies of the clinical effects and the human metabolism of high dosage kava are needed. Looming over all are questions of pharmacology. Do the kava pyrones possess anxiolytic or antipsychotic properties? Do they indeed have the property for which Pacific missionaries introduced them to Australia, as an alternative to alcoholism?



Soil Research ◽  
1972 ◽  
Vol 10 (1) ◽  
pp. 43 ◽  
Author(s):  
BG Williams

Soil salinity, pH, and Eh were determined in two soil types on the Adelaide River plains (Northern Territory) throughout the growing period of a rice crop. Both the total salinity, as indicated by specific conductivity values of the soil solution, and individual ion species were followed at 30 sites in each soil. The results demonstrated the existence of salt gradients within the soil profiles and these gradients, together with the total salt concentration and ion ratios, remained relatively constant throughout the growing season. The results are discussed in terms of experimental methods commonly employed for determining the effects of soil solution properties on rice culture.



2016 ◽  
Vol 64 (5) ◽  
pp. 303 ◽  
Author(s):  
Michael Westerman ◽  
Mark J. Blacket ◽  
Ashley Hintz ◽  
Kyle Armstrong ◽  
Patricia A. Woolley ◽  
...  

Multiple mitochondrial and nuclear gene sequences reveal substantial genetic variation within the dasyurid marsupial genus Planigale, suggesting greater taxonomic diversity than is currently recognised. To further investigate planigale relationships 116 new mitochondrial and nuclear gene sequences, including 16 new specimens, were added to our database. We confirm the presence of an unrecognised species (Planigale ‘species 1’) limited to the Pilbara region of Western Australia and suggest that the ‘Mt Tom Price’ animals may be closely related to Planigale ingrami subtilissima. We also confirm that at least four distinct genetic lineages make up what is currently recognised as P. maculata. This complex of closely related taxa represents a radiation of sibling species rather than a single, genetically diverse one. Three of these lineages (M1 + M2, M3 and M4) are distributed sympatrically across the Top End of Australia and one (M5 = P. maculata sensu stricto) is localised to the eastern coast of Australia. Within the Planigale ingrami complex, Planigale ‘Mt Tom Price’ (lineage Ing. 1) occurs in the Pilbara in sympatry with Planigale ‘species 1’ and lineage Ing. 2 is found in the Northern Territory in sympatry with species of the P. maculata complex. There is thus a plethora of northern Australian planigales, many of which are formally undescribed and whose geographic ranges require careful re-evaluation.



1995 ◽  
Vol 28 (2) ◽  
pp. 127-142 ◽  
Author(s):  
William Tyler

Recent attempts to involve the remote and small town communities of Northern Australia in their own policing and correctional services have often been held up as a model for developing Aboriginal criminal justice policies. Such a proposal raises important questions as to both the construction of the post-colonial ‘community’ in remote and settled Australia and the sociological principles by which these criminal justice schemes (eg night patrols, community wardens, community corrections) have been constituted. The paper explores the constructions of the Aboriginal community over the past two decades (ethnographic, politico-administrative and postmodernist) as a background to the development and implementation of community-based criminal justice schemes in the Northern Territory. A typology of post-colonial criminal justice strategies is developed which identifies four ‘ideal types’ in which the initiatives may be positioned. These are the mediative (community wardens, night patrols), the educative (community justice programs), the neo-colonialist (new forms of imposed European laws and policing) and the incorporative (pervasive and totalising forms of control). The possibility of transposing these Northern Territory schemes to other Aboriginal situations is then critically evaluated in the light of differing socio-political constructions of ‘community’.



1981 ◽  
Vol 8 (3) ◽  
pp. 207-215 ◽  
Author(s):  
J. E. Gardner ◽  
J. G. Nelson

At the very general level, the aim of this paper is to compare the interaction of national parks and native peoples in Northern Canada (Yukon Territory), Alaska, and the Northern Territory of Australia. Currently these areas are subject to increasing land-use pressures from mining, industrial development, the creation of national parks and related reserves, and native attempts to maintain traditional wildlife and renewable resource use. The study focuses on the interactions between national parks and native peoples on the premise that experiences can be compared and problems encountered in one area but possibly avoided in another.The study begins by briefly describing native land-use issues, land-rights arrangements, and organizations, in the Yukon Territory, central Alaska, and Northern Australia. The national park agencies are described, compared, and shown to differ considerably in institutional character, field of management, control of land, and external links with interest groups such as native peoples. Case-studies of the national parks etc. named Kluane (Yukon), Gates of the Arctic (Alaska), and Kakadu (Northern Territory of Australia), are presented to provide more details on similarities and differences in planning, types of tenure, native subsistence activities, and other factors.In the Yukon Territory, neither the national parks agency nor the native people are highly motivated to interact. In contrast, the park agencies and native people in Alaska and the Northern Territory of Australia recognize mutual benefits from interaction—largely as a result of legislation and policies which encourage cooperation. Native involvement officers now facilitate coordination in the Yukon and Alaska. Park agency native employment programmes are proceeding in all three ‘hinterlands’, while native people can own land on which national parks are established in Alaska and the Australian Northern Territory. Only in Australia are native people known to be directly involved in upperlevel national park management. Potential limitations on native subsistence and associated use of national parks range from moderate to severe, and are only defined clearly in Alaska. Lack of definition leads to confusion in deciding upon native use, while exceedingly precise definition precludes flexibility at the park level.A number of aids to a more mutually satisfactory interaction can be identified. One is motivation, or recognition by both parties that there are advantages to consultation and cooperation. Another, not yet achieved in the Yukon, is a land-claims settlement, stating the legislated rights of native peoples in the ‘hinterlands’ and giving them a land-holding and bargaining status which is comparable with that of government agencies. A third aid is comprehensive systematic and regional planning efforts involving opportunities for informed input from all affected parties. Such planning would provide a forum for consideration of a variety of interests, including national parks and native peoples. Finally, satisfactory interaction on the park site could be assisted by clear yet flexible means of deciding upon acceptable native use of parkland, the conservation of wildlife, and associated economic and cultural factors.



2020 ◽  
Author(s):  
Alana de Laive ◽  
Chris J. Jolly

ABSTRACT Chameleon Dragons Chelosania brunnea Gray, 1845 are well known amongst naturalists of northern Australia as being one of the most cryptic and least frequently observed of Australia’s large, iconic lizards. Despite their broad distribution across the savanna woodlands that dominate northern Australia, very few records exist of this species and, as a consequence, nearly nothing is known about their natural history. Here, we present records of 19 Chameleon Dragons, detected during clearing activities of a small area of semi-arid woodland at Delamere Air Weapons Range, Northern Territory. Additionally, we provide notes on sexual dimorphism, antipredator behaviour and shelter site use in this species. We discuss how some of this novel information may explain why this species is so rarely detected and suggests that this cryptic agamid may be much more common in savanna woodland than currently appreciated.



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