Recent publications in Science and Engineering

College of Science and Engineering Recent publications in Science and Engineering

Recent publications in Science and Engineering

Laurance, William (2018) Why scientists fear the AIIB. ChinaDialogue, 11 July 2018.
[Extract] As most chinadialogue readers will know, the Asian Infrastructure Investment Bank (AIIB) plans to catalyse investments in transport, energy and other projects across half the planet. I recently led a critique (http://alert-conservation.org/scientists-critique-aiib-transport-strategy/) by 34 leading environmental scientists, geographers, economists and development specialists of the AIIB's vision (http://www.aiib.org/en/policies-strategies/download/transport/2018_May_AIIB-Transport-Strategy.pdf) for funding and promoting transport projects. Our researchers hail from 16 industrial and developing nations and represent every major region of the globe, including China.

Eurich, Jacob G., Shomaker, Simone M., McCormick, Mark I., and Jones, Geoffrey P. (2018) Experimental evaluation of the effect of a territorial damselfish on foraging behaviour of roving herbivores on coral reefs. Journal of Experimental Marine Biology and Ecology, 506. pp. 155-162.
Roving herbivorous fishes play an important role in coral reef communities by removing turf-algae, which can facilitate the settlement of coral larvae. Territorial damselfishes can influence the foraging patterns of roving herbivores by excluding them from their territories, altering the benthic assemblage. However, the impacts depend on the intensity of aggression and which taxonomic groups of roving herbivores are being excluded. Here we document the foraging activity of roving herbivores (Acanthuridae, Scaridae, Siganidae) and the extent to which they are subject to aggression by Pomacentrus adelus, the most abundant territorial damselfish in Kimbe Bay, Papua New Guinea. We then conducted experimental removals (220 m2 plots on the reef flat) of P. adelus to examine its impact on roving herbivores and the benthic community structure. We hypothesized that the removal of P. adelus would lead to an increase in roving herbivore abundance and foraging activity and a decline in algal cover. The relative abundance (MaxN) and foraging activity (bite rate) of each taxa were examined pre and post-removal using video quadrats. The overall relative abundance of roving herbivores was not influenced by the removal of P. adelus. No changes in foraging patterns were observed for parrotfish, the family that received the highest rate of agonistic interactions, and rabbitfish. The removal of P. adelus resulted in a significant decrease in surgeonfish feeding, suggesting P. adelus alters foraging patterns indirectly through territorial maintenance and not aggression. The only measurable benthic impact of the P. adelus removal was an increase in sediment, while all other substratum types remained constant. These results indicate that P. adelus does not have a negative impact on all roving herbivores and instead may contribute to surgeonfish foraging indirectly through the removal of sediment. The generalisation that territorial damselfish reduce foraging rates of roving herbivores may not be applicable in all systems or for all species.

Bird, Michael I., Beaman, Robin J., Condie, Scott A., Cooper, Alan, Ulm, Sean, and Veth, Peter (2018) Palaeogeography and voyage modeling indicates early human colonization of Australia was likely from Timor-Roti. Quaternary Science Reviews, 191. pp. 431-439.
Anatomically Modern Humans (AMHs) dispersed rapidly through island southeast Asia (Sunda and Wallacea) and into Sahul (Australia, New Guinea and the Aru Islands), before 50,000 years ago. Multiple routes have been proposed for this dispersal and all involve at least one multi-day maritime voyage approaching 100 km. Here we use new regional-scale bathymetry data, palaeoenvironmental reconstruction, an assessment of vertical land movements and drift modeling to assess the potential for an initial entry into northwest Australia from southern Wallacea (Timor-Roti). From ∼70,000 until ∼10,000 years ago, a chain of habitable, resource-rich islands were emergent off the coast of northwest Australia (now mostly submerged). These were visible from high points close to the coast on Timor-Roti and as close as 87 km. Drift models suggest the probability of accidental arrival on these islands from Timor-Roti was low at any time. However, purposeful voyages in the summer monsoon season were very likely to be successful over 4–7 days. Genomic data suggests the colonizing population size was >72–100 individuals, thereby indicating deliberate colonization. This is arguably the most dramatic early demonstration of the advanced cognitive abilities and technological capabilities of AMHs, but one that could leave little material imprint in the archaeological record beyond the evidence that colonization occurred.

Miller, Rachel, Marsh, Helene, Cottrell, Alison, and Hamann, Mark (2018) Protecting migratory species in the Australian marine environment: a cross-jurisdictional analysis of policy and management plans. Frontiers in Marine Science, 5.
Marine migratory species are difficult to manage because animal movements can span large areas and are unconstrained by jurisdictional boundaries. We reviewed policy and management plans associated with four case studies protected under the Australian Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999) in order to identify the coherence of policy and management plans for managing marine migratory species in Australia. Environmental policies (n = 23) and management plans (n = 115) relevant to marine turtles, dugongs, humpback whales, and migratory shorebirds were reviewed. Few of the reviewed policies (n = 7) listed protected species and even fewer (n = 4) listed protected marine migratory species. Marine turtles were most represented in the reviewed policies (n = 7), while migratory shorebirds were most represented in management plans (n = 59). Policies and management plans were much more likely to identify relationships to other policies or plans within the same jurisdiction than to different jurisdictions. The EPBC Act 1999 served as the central link between reviewed policies and plans, but the requirements of that Act were weakly integrated into the other documents. This weak integration and the biases toward specific migratory species in environmental policies and management plans are detrimental to the conservation of these Matters of National Environmental Significance in Australia. Any changes to the EPBC Act 1999 will affect all environmental policy and management plans in Australia and highlights a need for cooperative, multi-level governance of migratory species. Our findings may have relevance to the conservation of marine migratory species in a broader international context.

To, P., and Sivakugan, N. (2018) Boundary stress distribution in silos filled with granular material. In: Numerical Methods in Geotechnical Engineering (1), pp. 863-868. From: NUMGE 2018: 9th European Conference on Numerical Methods in Geotechnical Engineering, 25-27 June 2018, Porto, Portugal.
Silo, a very popular structure in powder and mining industry, is a vertical container with an open outlet at the bottom and an optional inlet at the top. The design of silo requires a deep understanding of stress distribution at boundaries in both static and dynamic condition. Prior numerical studies use Finite Element Method or Finite Difference Method which shows an increase of vertical stress before it is leveled out by friction at a shallow depth. This is understandable for continuous media because the settlement caused by vertical stress must stop at some level. Nevertheless, experimental studies show that the vertical stress of the granular and porous media still increases with a constant rate even at a much greater depth. Although the Discrete Element Method (DEM) can simulate granular materials, it has some difficulties in determination of stress distribution because it is based on contact force, not the stress. This paper employs DEM with sphero-polyhedra shapes to simulate the behaviour of granular materials in silos. The stress distribution is calculated as average values. This requires a significant number of particles. Therefore, the paper focuses on narrowly graded materials. Some correlation with experimental data has been found.

Laurance, William F. (2018) Road mapping needs AI experts. Nature Communications, 558. p. 30.
[Extract] As road building expands globally, an automated system for detecting and mapping roads in near-real time is urgently needed to plan land use and conservation management. Machine-learning or artificial-intelligence (AI) specialists must help to meet this formidable challenge.

Muller, Benjamin John (2018) An examination of cane toad (Rhinella marina) behaviour: how can we use this knowledge to refine trapping regimes? PhD thesis, James Cook University.
Invasive species are of major concern to ecologists, because of their impacts on native fauna, communities, and ecosystems. Invasive species may alter the evolutionary pathways of native species by competitive exclusion, niche displacement, hybridisation, introgression, and predation, at times ultimately causing extinction. Further, the economic cost associated with invasive species, through losses in agriculture, forestry, and tourism, as well as the costs of preventing and controlling these species, are of major concern to land managers and governments. Specifically, the management of vertebrate invasive species is a crucial component of biosecurity, ecology, and land management. There are a range of control methods for invasive vertebrates, including hand-capture, trapping, baiting, shooting, and biological and genetic control methods. These control strategies vary in efficacy, depending on the life history and behaviour of the target species, the area over which removal occurs, and the method of delivery of the control. Understanding these factors assists with designing targeted control strategies, in which the chance of removal of each individual, or the impact of each capture, or both, is increased. The success of control methods for some invasive vertebrates has improved considerably over the last several decades, due to the ever-increasing body of research about the behaviour and life history of certain invasive species, and the refinement of control regimes in relation to new information. The invasive capabilities and impacts of amphibians generally receive less attention than other invasive vertebrates; as such, control methods for invasive amphibians are rare. Some invasive amphibians are generalist feeders, have high reproductive rates, and attain large population sizes; however, specific behavioural and life history traits are varied, and are often unknown. Further, abiotic factors, such as atmospheric temperature and moisture, effect the behaviour and activity of many amphibians. Current control strategies for invasive amphibians (e.g., hand-capture, exclusion fencing, and habitat modification) are often non-targeted, under-researched, and ineffective. Cane toads (Rhinella marina) are highly invasive anurans, native to south and central America. Their invaded range extends through many tropical areas worldwide, including Australia. Cane toad paratoid (shoulder) glands secrete powerful bufotoxins that are lethal to some native predators, and domestic pets. The impact pathways of cane toads on native species include poisoning after ingestion (both at larval and adult stages), and competition with other anurans. Further, the presence of cane toad tadpoles may affect growth rates of native tadpoles, while the presence of adults may affect calling behaviour of some native anurans. Potential control strategies for cane toads within their invaded range include hand-capture, tadpole traps, and biological and genetic control methods. These strategies are often non-targeted (e.g., tadpole traps, biological and genetic control methods), have been ineffective at suppressing toads for long periods, on a large scale, and in some cases require extremely high effort (e.g., hand-capture events). Trapping adult individuals using a solar-powered light and acoustic lure that automatically plays a cane toad call to attract toads into traps may be a viable control method that is easily refined to increase captures by exploiting behavioural characteristics of the cane toad. The success of any control method is dependent on the ability to refine it by targeting specific demographics of the invasive population, and increasing the number of captures per unit effort spatially, and temporally. Many control methods for cane toads are ineffective because they do not consider the activity patterns of toads in response to abiotic factors; however, understanding and exploiting these patterns could allay wasted effort. For example, land managers could augment captures by understanding the environmental conditions that drive activity, at different times of year, and focusing trapping effort on periods when toads are most active. I examined cane toad activity (numbers of captures) in response to several environmental variables (humidity, temperature, rainfall, wind speed, and moon luminosity) over eleven months of trapping. Captures were highest (i.e., toads were most active) in the wet season (Dec – Feb), and lowest in the dry season (Jun – Aug). In the wet season, wind speed and minimum temperature effected activity (toads were most active on warm, still nights), while rainfall was the strongest predictor of activity in the dry season. I suggest that land managers could allay wasted trapping effort by focussing on nights with conditions conducive to toad activity (e.g., wet nights during the dry season). It is important to determine the area over which toads are attracted to the call used as a lure in traps (the active space of the call), to aid in trap placement and the design of large scale trapping regimes. A vocalisation's active space is the area within which a receiver responds to it, while its maximum extent occurs when a receiver stops responding. I mapped behavioural responses of male and female cane toads to advertisement calls by conducting experimental playbacks to quantify the active space of calls for both sexes, separately. Both sexes displayed positive phonotaxis 20 – 70 m from calls. Males also displayed positive phonotaxis 70 – 120 m from calls, whereas females' movement preferences were random >70 m from a call. Differences between male and female responses were likely driven by differences in their use of information provided by calls. I suggest that traps should be placed m apart, such that a female toad can never be more than 70 from a trap, but effort is not wasted by 'over-trapping' in the target area. Targeting reproductively active females is the best strategy for reducing recruitment into the next generation, and is a common control technique for vertebrate pests with high reproductive rates. Female cane toads can lay over 10 000 eggs per clutch, and should be targeted, however current control regimes do not focus on the removal of females. The lures used in adult cane toad traps play an advertisement call used by male toads to attract females. In many anurans, females select mates based on the structural parameters of advertisement calls (e.g., dominant frequency and pulse rate), therefore modifying the parameters of calls used as lures in cane toad traps, to create especially attractive calls, may augment gravid female captures. I altered the frequency and pulse rate of artificial calls used as lures, and conducted several trapping regimes in and around the Townsville region in northern Australia, to determine which calls were most attractive to gravid females. Overall, gravid females preferred a 'combination' call with a low dominant frequency, and high pulse rate (relative to the population median for these parameters). Approximately 91% of the females trapped using a low frequency and high pulse rate combination call were gravid, whereas in traps using a call with population median parameters only approximately 75% of captured females were gravid. Calls that indicated large-bodied males (low frequency) with high energy reserves (high pulse rate) are often attractive to female anurans, and were effective lures for gravid female toads in my study. Often, advertisement calls differ among populations. In this case, the attractive 'combination' call I identified in the Townsville cane toad population may be less attractive to gravid females in other populations. I sampled calls from 4 cane toad populations across Australia (south east Queensland, north Queensland, Western Australia, and the Northern Territory), and constructed artificial vocalisations based on the median parameters of the sampled calls. I conducted trapping at each population, using calls tailored to each population, to determine which call was most attractive to gravid females in those populations. I created 'median' calls based on median call parameters of each population. I also manipulated the frequency and pulse rate of tailored calls from the population median by the same percentages as the altered parameters of the Townsville combination call (an artificially manipulated call with a low frequency and a high pulse rate, relative to the median values of these parameters in Townsville) to create a unique combination call for each population. Median calls, from Townsville or the local population, were always less attractive to females than combination calls. In south east Queensland, Western Australia, and the Northern Territory, there was no significant difference in mean nightly female captures between traps producing the Townsville combination call, and traps producing tailored combination calls for each population. In north Queensland, traps producing the Townsville combination call caught significantly fewer females than traps producing the tailored combination call for that region. I suggest that calls used as lures in traps should have tailored parameters derived from vocalisations in the area in which trapping occurs, to maximise gravid female captures. Cane toad management strategies should increase the chance of removal of every individual, by exploiting behavioural characteristics, and by increasing the period over which removal occurs. The lures in cane toad traps start and stop automatically, and operate all night, thus managers need only be on-site to remove trapped toads. Conversely, 'toad-busting' hand-capture events require participants to be on-site to find and remove toads, and may therefore be less efficient, in terms of captures per person-hour, than trapping. I used capture-mark-recapture analysis to compare the efficacy of trapping, and hand capturing cane toads, over 10 weeks, in Townsville, Australia. I trapped 7.1% - 22.4% of the estimated population per week, and hand-captured 1.7% - 6% of the estimated population per week. Trapping was more efficient than hand-capture in my regime; overall, more toads were caught per trapping person-hour than per hand-capture hour. Traps attract toads and maximise the period over which removal occurs, thus the probability of removal for each toad was higher than by hand-capture. Also, many toads caught in traps were not encountered during active searches, and vice versa, so the use of both methods, together, may be beneficial. I conclude the thesis by placing my research into an applied context, and exploring future directions for cane toad management.

Álvarez Noriega, Mariana, Baird, Andrew H., Dornelas, Maria, Madin, Joshua, and Connolly, Sean R. (2018) Negligible effect of competition on coral colony growth. Ecology, 99 (6). pp. 1347-1356.
Competition is an important determinant of assemblage structure and population regulation, often resulting in decreased growth, fecundity or survival. In corals, most studies testing for an effect of competition on demographic traits, such as growth, have been experimental and often impose very high levels of competition upon colonies. To more realistically assess the role of competition on coral traits, multispecies studies in the wild are required. Here, we use 5yr of data that includes 11 coral species on the reef crest at Lizard Island on the Great Barrier Reef to quantify the effect of competition on growth. Additionally, we test whether species differ in their susceptibility to direct-contact (overgrowth and digestion) and overtopping competition, and whether species from some morphological groups are more likely to compete with one another than with species from other morphological groups. We also investigate the relationships between competitive ability and three key traits: growth rate, mechanical stability and fecundity. In contrast to most previous work using field manipulations of competition, we found a negligible effect of competition on growth. Acropora species consistently won overtopping encounters but lost in direct-contact encounters, and these results were consistent among the four Acropora morphological groups. In contrast, the massive Goniastrea spp. were poor at overtopping but generally won direct-contact encounters. Only tabular colonies were disproportionally more likely to compete against one another than with other morphologies. This propensity increases intraspecific relative to interspecific competition, a phenomenon that can promote coexistence when it is present among dominant competitors. Good competitors grew more quickly and had higher fecundity but were less mechanically stable, implying a tradeoff between performance during disturbance vs. performance in the absence of disturbance. We conclude that competition among adults is less likely to influence community dynamics than previously thought. If competition does have an effect, it is more likely to occur at life-stages other than adults.

Mohandass, D., Campbell, Mason J., Chen, Xin-Sheng, and Li, Qing-Jun (2018) Flowering and fruiting phenology of woody trees in the tropical-seasonal rainforest, Southwestern China. Current Science, 114 (11). pp. 2313-2322.
The reproductive phenology of tropical plants is potentially driven by a number of abiotic and biotic factors. However, it is still unclear as to which climatic factors and biotic interactions drive the reproductive phenology of woody trees in the tropical seasonal rainforest of Xishuangbanna region in Southwest China. We conducted observations on woody plants (including trees and shrubs) phenology between November 2004 and October 2007 at bi-weekly intervals in the one hectare permanent plot of tropical seasonal rainforest in Southwest China. A total of 357 individuals of 76 species (70 genera, 37 families),comprising of 59 (78%) woody trees and 17(22%) shrub species were observed. Our results demonstrate that flowering an fruiting frequencies show slight temporal variation between years. Flowering was significantly correlated with day-length, temperature and rainfall and fruiting was significantly correlated with rainfall and temperature. This finding indicates that woody tree reproductive phenology was primarily associated with temperature and rainfall and to a lesser extent with day-length. Reproductive phenology is also linked to seasonal patterns with flowering peaking in the late dry season and fruiting peaking in the late wet season. Moreover, reproductive phenology is also significantly associated with reproductive ecological guilds such as pollination types and dispersal modes. Community reproductive phenology is associated with climatic seasonality and biotic interactions. It also suggests that seasonal phenology patterns may play a fundamental role in community reproductive success in the tropical seasonal rainforest of Xishuangbanna region of South-west China.

Addicott, Eda, Laurance, Susan, Lyons, Mitchell, Butler, Don, and Nelder, John (2018) When rare species are not important: linking plot-based vegetation classifications and landscape-scale mapping in Australian savanna vegetation. Community Ecology, 19 (1). pp. 67-76.
Plant communities in extensive landscapes are often mapped remotely using detectable patterns based on vegetation structure and canopy species with a high relative cover. A plot-based classification which includes species with low relative canopy cover and ignores vegetation structure, may result in plant communities not easily reconcilable with the landscape patterns represented in mapping. In our study, we investigate the effects on classification outcomes if we (1) remove rare species based on canopy cover, and (2) incorporate vegetation structure by weighting species’ cover by different measures of vegetation height. Using a dataset of 101 plots of savanna vegetation in north-eastern Australia we investigated first, the effect of removing rare species using four cover thresholds (1, 5, 8 and 10% contribution to total cover) and second, weighting species by four height measures including actual height as well as continuous and categorical transformations. Using agglomerative hierarchical clustering we produced a classification for each dataset and compared them for differences in: patterns of plot similarity, clustering, species richness and evenness, and characteristic species. We estimated the ability of each classification to predict species cover using generalised linear models. We found removing rare species at any cover threshold produced characteristic species appearing to correspond to landscape scale changes and better predicted species cover in grasslands and shrublands. However, in woodlands it made no difference. Using actual height of vegetation layer maintained vegetation structure, emphasised canopy and then sub-canopy species in clustering, and predicted species cover best of the height-measures tested. Thus, removing rare species and weighting species by height are useful techniques for identifying plant communities from plot-based classifications which are conceptually consistent with those in landscape scale mapping. This increases the confidence of end-users in both the classifications and the maps, thus enhancing their use in land management decisions.

To, P., and Sivakugan, N. (2018) Arching of granular flow under loading in silos. In: Numerical Methods in Geotechnical Engineering (1), pp. 857-862. From: NUMGE 2018: 9th European Conference on Numerical Methods in Geotechnical Engineering, 25-27 June 2018, Porto, Portugal.
Sublevel scheme is a major type of underground mining. At each sublevel, mine is blasted to form a silo, so that ore can be extracted from the bottom outlet of the silo. Due to the extraction, ground surface will have some significant subsidence, which can influence nearby infrastructure. To avoid this impact, a filling material might be stopped from upper sublevel during the extraction. This additional load creates spatial constraints for the granular flow and might stimulate the arching of this granular material. The research employs Discrete Element Method to simulate granular flow in silos under general vertical loadings. Particles are generated by Voronoi tessellation at a given porosity. The sample is shaken lightly so that particles can achieve a more random position and neutral contact. After that, they are released under gravity to form a granular flow. A parameter study is undertaken to find the condition of arching. A force is assigned to a top plane to simulate a top load, which increase stresses in force chains. The research draws out the influence of the geometry and top loads on arching probability in a silo.

Ulm, Sean, Cooper, Alan, Bird, Michael, Veth, Peter, Beaman, Robin, and Condie, Scott (2018) How to get to Australia … more than 50,000 years ago. The Conversation, 21 May 2018. pp. 1-5.
[Extract] Over just the past few years, new archaeological findings have revealed the lives of early Aboriginal Australians in the Northern Territory’s Kakadu potentially as early as 65,000 years ago, from the Kimberley and Pilbara regions of Western Australia by about 50,000 years ago, and the Flinders Ranges of South Australia by around 49,000 years ago. But how was it even possible for people to get to Australia in the first place? And how many people must have made it to Australia to explain the diversity of Aboriginal people today? In a study published in Quaternary Science Reviews this week, we use new environmental reconstructions, voyage simulations, and genetic population estimates to show for the first time that colonisation of Australia by 50,000 years ago was achieved by a globally significant phase of purposeful and coordinated marine voyaging.

Ascensão, Fernando, Fahrig, Lenore, Clevenger, Anthony P., Corlett, Richard T., Jaeger, Jochen A.G., Laurance, William F., and Pereira, Henrique (2018) Environmental challenges for the belt and road initiative. Nature Sustainability, 1. pp. 206-209.
The Belt and Road Initiative will greatly influence the future of global trade. However, it may also promote permanent environmental degradation. We call for rigorous strategic environmental and social assessments, raising the bar for environmental protection worldwide.

Konovalov, Dmitry A., Hillcoat, Suzanne, Williams, Genevieve, Birtles, R. Alastair, Gardiner, Naomi, and Curnock, Matthew I. (2018) Individual minke whale recognition using deep learning convolutional neural networks. Journal of Geoscience and Environment Protection, 6 (5). pp. 25-36.
The only known predictable aggregation of dwarf minke whales (Balaenoptera acutorostrata subsp.) occurs in the Australian offshore waters of the northern Great Barrier Reef in May-August each year. The identification of individual whales is required for research on the whales’ population characteristics and for monitoring the potential impacts of tourism activities, including commercial swims with the whales. At present, it is not cost-effective for researchers to manually process and analyze the tens of thousands of underwater images collated after each observation/tourist season, and a large data base of historical non-identified imagery exists. This study reports the first proof of concept for recognizing individual dwarf minke whales using the Deep Learning Convolutional Neural Networks (CNN).The “off-the-shelf” Image net-trained VGG16 CNN was used as the feature-encoder of the perpixel sematic segmentation Automatic Minke Whale Recognizer (AMWR). The most frequently photographed whale in a sample of 76 individual whales (MW1020) was identified in 179 images out of the total 1320 images provided. Training and image augmentation procedures were developed to compensate for the small number of available images. The trained AMWR achieved 93% prediction accuracy on the testing subset of 36 positive/MW1020 and 228 negative/not-MW1020 images, where each negative image contained at least one of the other 75 whales. Furthermore on the test subset, AMWR achieved 74% precision, 80% recall, and 4% false-positive rate, making the presented approach comparable or better to other state-of-the-art individual animal recognition results.

Everall, Tamara J., and Sanislav, Ioan V. (2018) The influence of pre-existing deformation and alteration textures on rock strength, failure modes and shear strength parameters. Geosciences, 8 (4).
This study uses the uniaxial compressive strength (UCS), the indirect tensile strength (ITS) and the point load tests (PLT) to determine the strength and deformation behavior of previously deformed and altered tonalite and anorthosite. In general, veined samples show higher strength because the vein material has both cohesive and adhesive properties while fractures have no cohesion, only frictional resistance. This implies that each rock category has to be treated independently and absolute strength predictions are inaccurate. Thus, the conversion factor k is a sample specific parameter and does not have a universal value. The ratio of UCS/ITS appears to be related to the rock strength and can be used to classify rocks based on their strength. The shear strength parameters, the friction angle and the cohesion, cannot be calculated for rocks with pre-existing planes of weakness. Reactivation is favoured only for planes oriented less than 20° to the maximum stress. For planes oriented between 20° and 50° to the maximum stress, failure occurs by a combination of reactivation and newly formed fractures, while for orientations above 50°, new shear fractures are favoured. This suggest that the Byerlee’s law of reactivation operates exclusively for planes oriented ≤10° to the maximum stress.

Niroshan, Naguleswaran (2018) Cemented paste backfill modification using different types of binders and insight into its mechanical, micro-structure, and flow properties. PhD thesis, James Cook University.
Cemented paste backfill (CPB) is widely used in backfilling underground mine voids. It consists of fine grained mine tailings with a small dosage of binder (~ 3–10%). Cement is the common binder, which is currently being used in most of the mines in North Queensland, Australia. In an effort to control backfilling costs, investigations are being currently carried out for the use of some alternative binders, that is, pozzolanic binder such as blended cement (BC) containing slag or fly ash in CPB. A thorough study to quantify the effects of additives, such as blast furnace slag and fly ash with ordinary Portland cement, in certain percentages on CPB could save large sums of money for Australian mining companies, if the required cement percentage is reduced in binder for CPB. In an attempt to dispose more tailings underground, the mines prefer increasing the solid content to the maximum possible limit, as dense CPB needs less binder to achieve a target strength. On the other hand, a high solid content slurry has both increased yield stress and viscosity, which increase the likelihood of blocking the reticulation pipeline. In this research, the possibilities of partial replacement of cement binder in CPB were studied through detailed laboratory investigations on influence of binder types as well as dosages in both mechanical and flow properties. Also, five different curing methods for CPB samples were studied to propose proper method. UCS test on 25 identical samples from three different CPB mixes were conducted for the detailed statistical analysis to assess the variability of mechanical properties of CPB samples and to validate the proposed curing method. Furthermore, the possibility of using a relatively smaller cylinder (110 mm height and 110 mm diameter) in slump test is assessed via extensive slump test along with standard slump cone on different CPB mixes. Moreover, series of scanning electron microscopy (SEM) analyses were performed on cracked UCS sample to investigate the relationship between microstructure and long-term mechanical properties. Finally, possibility of using UCS and indirect tensile (IDT) strength to determine the shear strength parameters (c and φ) for CPB was assessed with proper validation based on both experimental test and numerical simulation. For all these studies and investigations conducted in this research, various laboratory experiments, such as uniaxial compressive strength (UCS) test, indirect tensile (IDT) strength test, slump test, yield stress test, triaxial test and SEM analysis, with analytical correlation techniques and numerical simulation were employed. Slag blended cement (60% Slag + 40% Portland cement) can be used as replacement of cement binder in preparation of CPB with less dosage to achieve similar strength and stiffness as like cement binder, even in short curing time. This significant reduction in Portland cement usage not only leads to the significant cost saving, but also may slightly contribute for a sustainable development. In addition, through the extensive laboratory experiments on rheological properties, it is found that the there is hardly any difference between the cement and slag blended cement binders on flow properties namely the yield stress and slump, while the binder dosage has an effect. The smaller cylindrical slump device appears to have good potential for slurries like mine tailings or dredged mud that have high water content for slump test as there was strong correlation between the two different slump test devices used. Also, It is found that there is strong inter-relationship among solid content, slump, yield stress, and bulk density of CPB. In addition, a simple and proper curing method for CPB samples for the laboratory tests was recommended. In addition, the mechanical properties of CPBs cured in this proposed method show less variability for UCS and Young's modulus with relatively small coefficient of variation of less than 10% and 25%, respectively and hence these small variabilities of mechanical properties demonstrates the consistency of sample casting, curing, and testing methods. Furthermore, it is found that there is a positive relationship between microstructure and mechanical properties of CPB. Finally, the estimated shear strength parameters of CPB using the UCS and IDT strengths show good agreement with experimental and numerical simulation. Throughout the thesis, sets of empirical models and correlations were proposed to predict the long term UCS, stiffness, yield stress, slump height, and cohesion. In summary, the great potential of partial replacement of existing cement binder using slag blended cement in preparation of CPB is identified through various laboratory tests. In addition to the mechanical properties, the microstructure and flow properties of modified CPB were extensively investigated. This research will not only help to reduce the cement consumption in CPB production but also provides an alternative way of recycling industrial waste, such as slag and fly ash in vast volumes.

Rodgers, G.G., Donelson, J.M., McCormick, M.I., and Munday, P.L. (2018) In hot water: sustained ocean warming reduces survival of a low-latitude coral reef fish. Marine Biology, 165.
Tropical species are predicted to be particularly vulnerable to the impacts of climate change given the relatively narrow thermal range they naturally experience. Within the tropics, average temperature and thermal variation can differ among populations and consequently low-latitude populations may respond differently to increased temperatures than higher latitude tropical populations. In this study, we investigate the long-term effects of climate change relevant temperature increases on commonly measured condition metrics for a low-latitude population of damselfish (Acanthochromis polyacanthus). Adult fish were randomly assigned to one of the three seasonally cycling treatments: (1) current average ocean temperatures for the collection locations, (2) 1.5 °C, or (3) 3 °C higher than current average temperatures. Treatments were maintained for approximately 10 months. At the end of the experimental period, Fulton’s K and hepatosomatic index were calculated for fish from each treatment group and critical thermal limit (CTMax) was measured for a subset of fish at control temperatures. Fish mortality was recorded throughout the experimental period, as well as at the end of the experimental period after the introduction of a secondary exercise stressor. No significant effect of temperature was observed on fish condition (Fulton’s K and hepatosomatic index); however, significant mortality was observed for fish maintained at 3 °C higher than current average temperatures. When a secondary exercise stressor was introduced, significant mortality was also observed at 1.5 °C higher than current average temperatures. Acute exposure to higher temperatures (CTMax) suggested a much higher thermal tolerance for this population than long-term mortality, producing a thermal limit of 37.1 °C compared with a chronic thermal limit of 33 °C. Our results show that some basic measures of fish condition may not be capable of detecting lethal and sub-lethal effects of increased temperature. The results of this study are consistent with the hypothesis that low-latitude species are already living close to their thermal maximum.

Merino-Viteri, Andrés Ricardo (2018) The vulnerability of microhylid frogs, Cophixalus spp., to climate change in the Australian Wet Tropics. PhD thesis, James Cook University.
Climate change is a global phenomenon attributable to a change in concentration of greenhouse gases in the atmosphere as a consequence of human activities since the beginning of industrialisation. The change in climatic patterns direct and indirectly affects biodiversity by, for example, promoting geographic distribution changes (elevational or latitudinal) or affecting the biological interactions of species. These effects have been proposed to more severely affect ectotherms, especially in tropical regions. Tropical regions, due to annual climatic stability, may have promoted the evolution of species with reduced thermal tolerances. The endemic Microhylid frogs, genus Cophixalus, of the Australian Wet Tropics Bioregion (AWT) are considered one of the most threatened groups of vertebrates of the region by climate change. This vulnerability mainly comes from a reduced geographic distribution, restricted to a one or few mountain tops in the coldest, wettest and aseasonal parts of the AWT. These nocturnal frogs are forest floor dwellers and reproduce via direct development (i.e. eggs are deposited terrestrially and development occurs within the egg with froglets hatching from the egg capsule). During day time they seek shelter from ambient environmental conditions in refuges (mainly under logs, rocks or fallen epiphytes). Correlative models of distribution of this group of frogs predict a reduction of suitable climatic area in the future, however the mechanisms behind the potential changes are poorly understood. The ecological characteristics of Cophixalus and their high regional species richness (thirteen species) make this group ideal to test hypotheses about factors that influence their geographical distribution limits and potentially will influence their response to future climates. A more accurate assessment of the vulnerability of these Cophixalus frogs to climate change depends on the understanding of the conditions the species actually are exposed to and their sensitivity to environmental change. Exposure requires accurate microenvironmental data and an understanding of seasonal or daily behavioural activity, while sensitivity can be assessed by directly quantifying the physiological thermal tolerances of the animals. Cophixalus frogs show a consistent daily and seasonal activity pattern showing adaptations to exploit available refuges with potentially better buffering capacity, which may be important to face warmer conditions in the future. Based on behavioural observations, a sequence of actual exposure conditions for Cophixalus frogs was constructed. Exposure conditions were found to be behaviourally buffered from ambient air conditions (by nocturnality and microhabitat use). This magnitude of the buffering varies with season, being higher during the warmest months. Sensitivity of Cophixalus frogs was directly measured using several techniques including a dynamic method to determine critical thermal maximum and minimum. The experimental device increased or decreased temperature at a rate of approximate 1˚C/minute, until organisms lost righting capacity. The analysis of the sensitivity of organisms to climate change must be based on empirical evidence, to improve the assessment of future climate impacts. Observed thermal tolerances and limits of the Australian Wet Tropics Cophixalus frogs was not predicted by phylogenetic history, but instead was correlated with contemporary environmental conditions associated with the geographical distribution of individual species. Cophixalus frogs have narrow thermal ranges that may be explained by their narrow geographical restriction to rainforest habitats. Historical stability of environmental conditions within this ecosystem, has been proposed as a major driver of species distribution patterns and subsequent geographic species richness in this region. The maximum thermal tolerance (CTmax) of the eleven species of Cophixalus examined, ranged from 28.1 °C to 35.9 °C, and the minimum (CTmin) ranged from 8.6 °C to 14.3 °C. Thermal tolerance range was extremely narrow compared with other tropical anurans, even for the species with the widest tolerance, Cophixalus exiguus (25.5 °C). Mean and mode of the preferred temperature showed similar values ranging from 20 °C to 29 °C across the 13 species. The combination of measured thermal tolerances, microenvironmental exposure and ecology of species will be fundamental for the development of more accurate assessment of vulnerability to climate change. For restricted species, the analysis of these factors may also allow the identification of parameters that may be limiting their distributions. In this study, available evidence suggests that thermal physiology parameters of individual Cophixalus frogs, such as CTmax is correlated to different distribution characteristics (e.g. maximum and mid-altitude of the species distribution). These data also allow us to determine whether species are actually filling their fundamental thermal niche. It is suggested that some species are not filling their niche. This finding may open the possibility to explore conservation strategies that may include translocation of individuals to regions where they are not currently present but environmental conditions would not act as a limitation. When predictions of temperature change are included in the analysis, the results may be used to guide decisions about the regions and time frames when conservation strategies are required. Climate conditions under present, and two future frames (2035 and 2065) were evaluated. Our results suggest that some species may be experiencing suppressed fitness due to environmental warming even under current environmental conditions. This decrease is related to exposure to conditions warmer than their preferred temperature. The exposure to these stressful conditions are expected to occur first in the lower elevational areas of the distribution and increase in magnitude into the future. One of the most important findings of this research is that our data suggests that no population of any Cophixalus species occurring in the AWT will be exposed to temperatures that directly cause fatalities within the timeframes evaluated. This is important because it suggests that drastic interventions to avoid local extinctions will not be necessary by 2065. However, the potential for serious indirect, or synergistic, impacts remains. It is possible too that physiological responses to environmental parameters other than temperature may limit distributions of Cophixalus species. Another contribution of this study was to develop an experimental apparatus capable of quantifying tolerance to desiccation in hard field conditions. We provide a description of the experimental apparatus and detailed methodology as an input for future studied focused on this environmental parameter and also include some preliminary data on desiccation rates as an appendix. Cophixalus frogs show an increase of water loss with temperature, implying an increase in vulnerability to drying in the future. Cophixalus neglectus in particular seems to be highly sensitive to desiccation. Cophixalus saxatilis presents low levels of desiccation that can be explained by larger size of the species and relative low relation between surface-area and volume of individuals. Cophixalus monticola shows low water loss rates compared to close relatives of similar size. This pattern may be related to specialisation on Limnospadix palms as a preferred microhabitat which may offer less protection against water loss than other microhabitats. The combined information assembled in this research addresses some of the important knowledge gaps identified by national authorities, needed to improving the understanding of mechanisms behind climate change impacts. This new knowledge provides a basis for the development of more robust and accurate conservation strategies that will increase the success of adaptive management focused on the conservation of species threatened with extinction, such as the Australian endemic Cophixalus frogs.

Wang, E., Attard, S., Everingham, Y., Philippa, B., and Xiang, W. (2018) Smarter irrigation management in the sugarcane farming system using internet of things. In: Proceedings of the 40th Annual Conference of the Australian Society of Sugar Cane Technologists (40), pp. 117-122. From: ASSCT 2018: 40th Annual Conference of the Australian Society of Sugar Cane Technologists, 17-20 April 2018, Mackay, Queensland.
Irrigation management is a considerable time investment for many sugarcane farmers. Better irrigation practices can lead to improved yields through less water stress, and reduce water usage to deliver economic benefits for farmers. The reduced runoff and deep drainage from excess irrigation can also deliver benefits to the environment. The Internet of Things (IoT) is about allowing things to sense, to communicate, and thus creating opportunities for more direct integration between the physical world and computer-based systems. IoT has been transforming all spheres of life into smart homes, smart cities, and smart healthcare. Today’s farms can leverage IoT to remotely monitor sensors, manage and control harvesters and irrigation equipment, and utilise artificial intelligence based analytics to quickly analyse operational data combined with third party information, to provide new insights and improve decision-making. This project focuses on improving irrigation management by integrating the auto-irrigation system (e.g., WiSA) and IrrigWeb (a sugarcane irrigation scheduling tool) to provide a smarter irrigation solution using IoT. The system generates a two-way communication channel between these two platforms, which allows them to share data. Specifically, the uplink program (WiSA to IrrigWeb) was developed and deployed in a Burdekin farm. It connects the farmer’s WiSA to IrrigWeb, by uploading irrigation data automatically. The farmer’s irrigation records are automatically loaded into IrrigWeb. This saves the farmer time and makes the scheduling more efficient. Another benefit is that the farmer can now see the exact amount being applied to each field, and make modifications to the irrigation management, if required. Moreover, automating the data transfer from WiSA to IrrigWeb will greatly improve the potential for uptake and use of technologies like IrrigWeb. On the other hand, the downlink program (IrrigWeb to WiSA) will be developed to automatically apply scheduling from IrrigWeb to WiSA. Combining the uplink and downlink programs, a smarter irrigation management system can automatically control sugarcane irrigation, and ultimately make sugarcane irrigation fully autonomous.

Jayasinghe, Nandana Chana, Ginger, John D., Henderson, David J., and Walker, George R. (2018) Distribution of wind loads in metal-clad roofing structures. Journal of Structural Engineering, 144 (4).
The roof is the part that experiences the largest wind load and is usually the most vulnerable part of a house. However, data on how the wind loads are transferred through the roof structure are scarce. The fluctuating nature and variable spatial distribution of wind loads combined with the structural response can cause significant challenges for assessing the distribution or sharing of loads in a roof. Such studies are required to obtain more reliable estimates on vulnerability assessment to windstorms. This paper describes the transmission of wind loads from the pressure on the cladding through the cladding-to-batten connections to the batten-to-truss connections on a roofing system typical of that in many contemporary houses constructed in cyclonic regions of Australia. The study found that the use of normal design practices can significantly underestimate connection loads when highly correlated large-scale wind pressures act on these roof systems.

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