Salmonella in free-ranging quokkas (Setonix brachyurus) from Rottnest Island and the mainland of Western Australia

Salmonella is a genus of Gram-negative, motile, and facultative anaerobic bacteria with a worldwide distribution that contaminates multiple substrates (vegetation, food, soil, and water) and inhabits the gastrointestinal tract of birds, reptiles, and mammals, including humans. Rottnest Island is a popular tourist destination and is abundantly inhabited by quokkas (Setonix brachyurus), a charismatic small wallaby. Current data on the association between Salmonella and quokkas on Rottnest Island are outdated by approximately 30 years. Additionally, previous studies on quokkas on this island and mainland Western Australia did not perform physical examinations or any diagnostic tests. The aim of the project was to assess the prevalence of Salmonella spp. in quokkas from Rottnest Island and mainland Western Australia and correlate the presence of the bacterium with the health of the animal. Ninety-two quokkas from Rottnest Island (n = 71) and populations on the mainland (n = 21) were screened for Salmonella, and a prevalence of 47.9% and 4.8%, respectively, was determined. A total of 16 serovars were identified from 37 isolates; five of these serovars had previously not been described in the quokka. Salmonella appeared to have an effect on the haematology and blood chemistry of quokkas on Rottnest Island consistent with subclinical salmonellosis. The health of Rottnest Island quokkas, and their potential impact on the health of the visitors to the island, should continue to be monitored carefully

A 2500 year old pseudo shell midden on Longreach Bay, Rottnest Island, Western Australia.

On several occasions during the past decade, Perth-based and occasional visiting Quaternary researchers have examined possible prehistoric human occupation sites on Rottnest Island, 20 km west of Fremantle, WA. The following describes findings from recent investigations of possible prehistoric midden material from a site on Longreach Bay, Rottnest Island

Ecological impacts of Australian Ravens on bush bird communities on Rottnest Island

The Australian Raven Corvus coronoides is a predator of the eggs and nestlings of bush birds on Rottnest Island, Western Australia. Nest predation is a threatening process of island birds, and when combined with other threatening processes, such as habitat fragmentation and degradation, sustained nest predation can cause declines in bush bird communities. The terrestrial habitats on Rottnest Island have been historically fragmented through land clearing, so concern was raised by the Rottnest Island Authority regarding the impact of the Australian Raven on bush bird communities. The aims of this study were to describe the ecology of the Australian Raven on Rottnest Island, in particular the feeding ecology, and to evaluate how important bush birds are in the diet of the Australian Raven. To determine the rate of nest predation by the Australian Raven, an artificial nest experiment was conducted over four months from August to November, over six study sites. The diet of the Australian Raven was analysed by laboratory examination of raven stomach samples. In addition, observational data collected at the study sites during the study period was used to quantify the behaviour, abundance and distribution of ravens, and compared to bush bird distribution on Rottnest Island. During this study, ravens predated 20% of the artificial nests, indicating a high capacity for potential population impacts. Nest predation was confirmed by the presence of birds in the stomach contents of ravens from Rottnest, but plant material and invertebrates were found to be more important in the diet. The Australian Raven prefers the disturbed and urban habitat areas of Rottnest Island for feeding, roosting and breeding. Bush birds avoid these areas, and prefer remnant and revegetated areas. The results of this study have identified the Australian Raven as a potential predator of nesting bush birds on Rottnest Island. However, restoration of island vegetation may be having a positive effect on bush bird communities that outweighs losses of eggs and nestlings to ravens. In view of these results, continued management of the raven population is recommended as a precautionary approach so that the impacts of nest predation on bush birds are limited. Meanwhile, the population dynamics of selected bush birds can be assessed to confirm that they are recovering in response to habitat restoration programs

Health and disease status in a threatened marsupial, the quokka (Setonix brachyurus)

Between 1901 and 1931, there were at least six anecdotal records of disease outbreaks in mainland quokkas (Setonix brachyurus) that were associated with mass mortalities. This time period pre-dates the arrival of the red fox (Vulpes vulpes). Despite these outbreaks, little or no research has been carried out to establish health and disease baseline data of the fragmented and scattered, extant populations. Epidemiological data was determined for a range of potential pathogens, and established physiological reference intervals of apparently healthy, wild quokkas on Rottnest Island and mainland locations. There were significant differences between Rottnest Island and mainland quokkas. Rottnest Island animals had haemograms with mark evidence of oxidative injury and bone marrow response consistent with a regenerative normocytic hypochromic anaemia. Except alkaline phosphatase (ALP), all blood chemistry analytes where higher in mainland animals, with particular emphasis on creatine kinase (CK), alanine amino transferase (ALT), aspartate amino transferase (AST) and vitamin E. Some other key findings include a widespread presence of a novel herpesvirus (MaHV-6), the recovery of Cryptococcus neoformans var. grubii from quokkas in highly altered ecosystems on Rottnest Island, and new Salmonella spp. serovars in Rottnest Island quokkas. Atypical lymphocytes resembling those in proliferative disorders of the lymphoid and haematopoietic tissues in other species were observed in blood smears of animals on Rottnest Island but not on the mainland. The presence of potentially-pathogenic organisms is likely to increase synergistic effects of ongoing and future threats (e.g. habitat clearing, climate change), and could increase quokka extinction risk. Disease surveillance would make a valuable contribution to Recovery Plans for the quokka, enabling preparedness for a rapid response if clinical disease is to happen, and to manage populations in a more integrated way

Australasian Arachnology, Number 72, August 2005

Just days before this newsletter went to the printer, the Australasian Arachnological Society launched its own website: www.australasian-arachnology.org It was a great effort from all involved, but two people in particular (who are not even directly involved with our society) deserve a special mention: Randolf Manderbach (web programming) and Thomas García Godines (graphic design) professionally developed and programmed the lay-out of our website, for free! Thanks to both of them! You will find further acknowledgements and some information in regard to the ‘philosophy’ of our site in an introductory article on page 4. Similar to this newsletter, the website will prosper only through contributions and feedback from all of you

Responses of intertidal invertebrates to rising sea surface temperatures in the southeastern Indian Ocean

Introduction: The west coast of Western Australia (WA) is a global hotspot for increasing sea surface temperatures and marine heatwaves. Methods: We used visual survey transects to compare mollusc and echinoderm populations on three coastal intertidal platform reefs on the Perth shoreline with two intertidal platforms at the west end of Rottnest Island (32°S) which are under the influence of the southward flowing Leeuwin Current. Results: In 1983, temperate species dominated Perth coastal molluscan diversity, but the tropical mussel Brachidontes sculptus dominated density. Species richness on coastal platforms remained constant in 2007 and 2021, but total densities were lower in 2007 as B. sculptus declined; partial recovery occurred on coastal platforms in 2021. Tropical species were a significant component of mollusc diversity and density at Rottnest Island in 1982 and 2007. Total mollusc density declined by 98% at the island sites of Radar Reef and 86% at Cape Vlamingh and total echinoderm density by 52% and 88% respectively from 2007 to 2021; species diversity also declined sharply. Discussion: Tropical species have moved southward in WA subtidal environments, but tropical, temperate and WA endemic species all suffered losses of biodiversity and catastrophic declines in density of 90% or more on the two Rottnest Island intertidal platforms. Data presented here provide a sound basis for exploring the possible causes of the catastrophic mortality at the west end of Rottnest Island and monitoring for recovery

The palaeoceanography of the Leeuwin Current : implications for a future world

Long-term progressive changes of the Leeuwin Current are linked to plate and ocean basin ‘geography’ and Cenozoic global climates and palaeoceanography. Suggestions of the presence of a proto-Leeuwin Current as early as late Middle to Late Eocene times (c. 35–42 Ma) cannot be verified by the fossil record of the western margin of Australia. “Leeuwin Current style” circulation around Australia was certainly established by the early Oligocene, in response to palaeogeographic changes in the Tasman Strait. This, followed by tectonic eorganisation of the Indonesian Archipelago throughout the Miocene, provided a palaeogeographic setting, which by the Pliocene was essentially that of today. The subsequent history of the Leeuwin Current comprises climatically-induced changes operating over orbital and sub-orbital temporal scales. Specifically, the advent of Pleistocene-style climates, especially over the last 800 000 years, and their associated interglacial – glacial states provide the two end-member climate-ocean states that have characterised Leeuwin Current activity during that time. Indications of the nature of these contrasting states is provided by: (i) the Last Interglacial (c. 125 Ka) during which sea level was higher by some +4 m, and with higher sea surface temperatures (SSTs) clearly indicating a more ‘active’ Leeuwin Current; and (ii) the Last Glacial Maximum (21 Ka), during which sea level wassome 130 m lower than today, resulting in massive shelf extensions along the coast of Western Australia, ccompanied by reduced Indonesian Throughflow, lower low latitude SSTs and changes in the Western Pacific Warm Water Pool, and with these changes, possibly reduced Leeuwin Current activity. Sub-orbital scale luctuations in current strength are driven by global climate change associated with El Niño – La Niña events as well as regional climatic changes driven by volcanism. These forcing mechanisms operate at time scales well within the reach of human experience, and provide important comparative data for predicting the response of the Leeuwin Current to climate change predicted for this century. Studies of the impact of changes in the vigour of the Leeuwin Current on shallow marine communities are in their infancy. Coupling climate models with geological analogues provide important research agenda for predicting the trajectory of future changes to the Leeuwin Current and their impacts on the marine biota of coastal Western Australia

Land resource survey of Rottnest Island - an aid to land use planning

This report provides a description of the landforms, soils and vegetation of Rottnest Island. In addition, it provides a discussion of the relative capability of each of the landforms of the island to sustain various forms of development. The primary objective of this work is to direct development into areas of high capability (low risk of land degradation) in preference to areas of lower capability (higher risk of land degradation). Rottnest Island is located approximately 30 km west of Perth. The proximity of the island to the capital city of Western Australia, its warm Mediterranean climate and the subsequent likelihood of further development, mean that there will be increasing pressure on the natural resources of the island. This report details the nature and inherent stability of those natural resources, and provides a guide for their management.https://researchlibrary.agric.wa.gov.au/bulletins/1062/thumbnail.jp

An Exploration of 1st and 2nd Generation CPTED for End of Year School Leavers at Rottnest Island

The end-of-year post exam celebrations for Year 12 secondary school students presents a unique crime prevention proposition in Australia each year. Students of approximately 17 years of age congregate in a variety of locations in large groups known as ‘Leavers’. Traditionally a number of \u27rite of passage\u27 activities, fuelled by additional factors such as alcohol, drugs and peer pressure, have resulted in an increased risk of crime and anti-social behaviour. This paper examines mitigation strategies aligned with Crime Prevention Through Environmental Design (CPTED) when placed at an event. Using the annual Leavers cohort at Rottnest Island, W.A., a number of 1st and 2nd generation CPTED instruments are discussed and evaluated. The additional isolation factor of the island highlights the value of 2nd generation social cohesion and its likely impact in reducing a number of crime-related social issues. The paper concludes that increased 2nd generation CPTED treatments significantly improve crime reduction and fear of crime in temporary locations when used for mass gatherings at events