South-eastern Australia Research Articles

A systematic review on the anthropogenic stressors on sessile benthic mesophotic reef communities: implications for temperate reef management in Australia

Temperate rocky reefs are complex habitats that support high levels of biodiversity and productivity. However, the sessile benthic communities attached to these reefs are vulnerable to climate change and local human impacts due to their limited capacity to rapidly avoid unfavourable environments. In southeastern Australia, high latitude rocky reefs face increasing threats from rapid warming, surpassing the global average. Existing management efforts for these reefs rely heavily on research from tropical coral ecosystems and shallow temperate algal-dominated rocky reefs, where sufficient data allows for reliable predictions on the future state of the systems. Recent evidence from seabed mapping programs indicates that mesophotic reefs (~30-150 m depth) are equally or more extensive than shallow systems in temperate waters. They provide novel ecosystem functions and could potentially act as climate refuges for some components of shallow water communities that extend across depth strata. However, despite their importance, very little is known about the threats faced by non-algal sessile organisms in either shallow water or mesophotic systems in many parts of the world, including temperate Australia. This review examined the current state of knowledge regarding the direct impact of physical disturbances, such as extreme weather events, ocean warming and destructive fishing practices, on sessile mesophotic communities in general. We then used this to infer the likely drivers of change in temperate mesophotic systems. We found that Australia’s temperate mesophotic ecosystems were less likely to be impacted by fishing, anchoring and lost fishing gears compared to the northern hemisphere due to lower population density. Instead, we identified present and future pulsed warming events and severe storms as major threats to Australia’s mesophotic systems. This conclusion is based on the lack of evidence supporting the existence of depth refuges from climate events in the current literature and the potential implications of the predicted future increases in high wind-wave energy and warming extending into the mesophotic depths. Drawing from observations globally, changes in the distribution of growth forms, size or diversity of sponges may be useful indicators of heat stress and seabed disturbances in temperate mesophotic systems.

Hyporheic Tateidae (Gastropoda: Truncatelloidea) from the Flinders Ranges, South Australia and Judbarra (Gregory) National Park, western Northern Territory, Australia, with some taxonomic notes on the family

ABSTRACT Four new species of phreatic tateids from stream sediments in Australia are described. One, from intermittent streams in the Flinders Ranges, South Australia, is a highly modified species of Austropyrgus, a genus widespread in south-eastern Australia and Tasmania. The other three species are included in the new genus Turricochlea and live in sympatry in gravel in a creek bed in the Gregory National Park in the western part of the Northern Territory. Molecular analysis showed that Turricochlea and ‘Fluviopupa’ kessneri are closely related to Sulawesidrobia from Sulawesi but not Fluviopupa, so the new generic name Austropupa is provided for F. kessneri. Two new family names are proposed for taxa previously included in Tateidae: Beddomeiidae and Ascorhiidae.

Short-interval, high-severity wildfires cause declines in soil seed bank diversity in montane forests of south-eastern Australia

Wildfires in forested ecosystems are increasing in severity and extent. The adaptations many plants have acquired in response to their natural fire regime may not be sufficient to allow some species to persist. This could impact the forest understorey and its seed bank, which are vital reservoirs of biodiversity, and forest resilience in the face of global change. We present a case study of the montane forests of south-eastern Australia, an area subjected to an increase in frequency and severity of fires. We utilise field surveys and a soil seed bank germination study to investigate if short-interval, high-severity wildfires affect the understorey diversity in montane forests, and if the extant vegetation and the soil seed bank exhibit contrasting responses. We consider species diversity and plant functional traits to explore plant diversity in long unburned sites, and sites with one, two or three short-interval, high-severity fires in the past 25 years. With increasing fire frequency, we found a decrease in total species richness, Shannon’s diversity, and the richness of resprouters in the soil seed bank, contrasting a lack of response in the extant vegetation. Increased fire frequency shifted the species composition and the frequency of plant functional groups of both extant vegetation and soil seed bank towards a decrease in clonal resprouters and increase in grasses and other upright herbs. The frequency of wind-dispersed perennials and short-lived seeders and exotics increased sharply following single high severity burn, particularly in the soil seed bank, and remained elevated relative to long unburnt with subsequent fire. The combined species (extant vegetation plus soil seed bank) pool mirrored shifts in the frequency of functional groups in extant vegetation and soil seed bank. These findings highlight the importance of considering the soil seed bank when examining the effects of fire on fire-prone forests. Although a lack of response in the extant vegetation may be a buffering effect of the soil seed bank, the shift in the frequency of plant functional groups in the combined species pool suggests this cannot be maintained indefinitely. The increase in frequency and abundance of species characteristic of early successional states has implications for increased flammability and potential positive feedbacks between past fire and future fire, especially in a warming and drying climate. These shifts were independent of the fire response strategy of eucalypt canopy species raising significant questions of whether artificial re-seeding programs should extend beyond the current focus on obligate seeding forests and an obligate seeding tree.

Fishways provide catchment-scale improvements to common galaxias (Galaxias maculatus) upstream of a barrier in south-eastern Australia

ABSTRACT The common occurrence of dams is a major threat to riverine fish communities globally and a common remediation technique for fragmented fish communities is fishway construction. Demonstrating the effectiveness of this technique on impacted species is required to rationalise or improve management practices. This study investigates the effects of the installation of a fishway complex on the catadromous common galaxias (Galaxias maculatus) population at a catchment scale. We used electrofishing in a before-after-control-impact design to investigate the effects of the installation of a rock-ramp and a vertical-slot fishway complex on this species. This study demonstrated an increase in the relative abundance of common galaxias of 7.6–28.1 times and a shift to higher proportions of small fish in tributaries upstream of the fishway complex (as far as 90 km upstream). These findings provide strong evidence for the efficacy of the installation of fishways to increase the number of catadromous fishes in rivers where fish migrations have been blocked by dams.

A new species of Planipapillus (Onychophora: Peripatopsidae) that defies the original concept of its genus

Douch, J.K. and Reid, A.L. 2023. A new species of Planipapillus (Onychophora: Peripatopsidae) that defies the originalconcept of its genus. Memoirs of Museum Victoria 82: 257–262. Planipapillus Reid, 1996 (Onychophora: Peripatopsidae) is a genus of peripatus or velvet worms from south-eastern Australia, consisting of 12 nominal species, unique in having a patch of reduced papillae on the heads of males. Specimens from Mt Useful, Victoria, that lack this trait were identified as a species of Planipapillus on the basis of morphological and molecular analyses in 1999 and 2001, respectively. That species is herein described as P. absonus sp. nov., and an emended diagnosis for the genus is provided to accommodate this unusual addition. The relationship between modified head papillae and mating is discussed.

Tasmaniomyxa umbilicata, a new genus and new species of myxomycete from Tasmania

ABSTRACT A new genus and species of myxomycete, Tasmaniomyxa umbilicata, is described based on numerous observations in Tasmania and additional records from southeastern Australia and New Zealand. The new taxon is characterized by an unusual combination of characters from two families: Lamprodermataceae and Didymiaceae. With Lamprodermataceae the species shares limeless sporocarps, a shining membranous peridium, an epihypothallic stalk, and a cylindrical columella. Like Didymiaceae, it has a soft, flaccid, sparsely branched capillitium, with rough tubular threads that contain fusiform nodes and are firmly connected to the peridium. Other characters of T. umbilicata that also occur in many Didymiaceae are the peridium dehiscing into petaloid lobes, the yellow, motile plasmodium, and the spores ornamented with larger, grouped and smaller, scattered warts. The transitional position of the new taxon is reflected by a three-gene phylogeny, which places T. umbilicata at the base of the branch of all lime-containing Physarales, thus justifying its description as a monotypic genus.

Chlamydia psittaci: an emerging cause of equine abortion and fatal neonatal illness in south-eastern Australia.

While well known as a zoonotic pathogen of birds, Chlamydia psittaci is less well recognised as a cause of abortion in mares and severe infection in foals. However, in the past decade it has been causing epizootics of both in south-eastern Australia, as Charles El-Hage and James Gilkerson explain.

Determining energy expenditure in a large seabird using accelerometry.

The trade off between energy gained and expended is the foundation of understanding how, why and when animals perform any activity. Based on the concept that animal movements have an energetic cost, accelerometry is increasingly being used to estimate energy expenditure. However, validation of accelerometry as an accurate proxy for field metabolic rate in free-ranging species is limited. In the present study, Australasian gannets (Morus serrator) from the Pope's Eye colony (38°16'42″S 144°41'48″E), south-eastern Australia, were equipped with GPS and tri-axial accelerometers and dosed with doubly labelled water (DLW) to measure energy expenditure during normal behaviour for 3-5 days. The correlation between daily energy expenditure from the DLW and vectorial dynamic body acceleration (VeDBA) was high for both a simple correlation and activity-specific approaches (R2=0.75 and 0.80, respectively). Varying degrees of success were observed for estimating at-sea metabolic rate from accelerometry when removing time on land using published energy expenditure constants (R2=0.02) or activity-specific approaches (R2=0.42). The predictive capacity of energy expenditure models for total and at-sea periods was improved by the addition of total distance travelled and proportion of the sampling period spent at sea during the night, respectively (R2=0.61-0.82). These results indicate that accelerometry can be used to estimate daily energy expenditure in free-ranging gannets and its accuracy may depend on the inclusion of movement parameters not detected by accelerometry.

Quality of life in south-eastern Australia: normative values for the WHOQOL-BREF in a population-based sample of adults

ObjectivesThe abbreviated World Health Organisation Quality of Life tool (WHOQOL-BREF) is a short-form quality of life (QoL) assessment commonly used worldwide in both healthy and ill populations. Normative data for...

Relative contribution of photodegradation to litter breakdown in Australian grasslands.

Grassy ecosystems cover ~40% of the global land surface and are an integral component of the global carbon (C) cycle. Grass litter decomposes via a combination of photodegradation (which returns C to the atmosphere rapidly) and biological decomposition (a slower C pathway). As such, decomposition and C storage in grasslands may vary with climate and exposure to solar radiation. We investigated rates of grass litter decomposition in Australian temperate grasslands along a climate gradient to uncouple the relative importance of photodegradation and climate on decomposition. Litterbags containing leaf litter from two common native grass species (Poa labillardierei, Themeda triandra) were deployed at six grassland sites across a precipitation gradient (380-890 mm) in south-eastern Australia. Bags were retrieved over 39 weeks to measure mass loss from decomposition. We used shade treatments on the litter of one species (T. triandra) to partition photodegradation from biological decomposition. The shade treatment reduced the rate of decomposition of T. triandra relative to the full-sun treatment at all sites, by an average of 38% at 39 weeks; the effect size of the shade treatment was not correlated with site productivity. The rate of decomposition in both species was positively correlated with rainfall midway through the experiment, but there were no significant differences in total decomposition among sites after 39 weeks. By week 39, total decomposition of T. triandra was significantly greater than for P. labillardierei. In general, we observed relatively linear decomposition rather than the strong negative exponential decay observed in many global litter decomposition studies. Synthesis: We found that solar radiation exposure was a strong contributor to litter decomposition in temperate Australian grasslands across a broad climate gradient, which may be related to a period of photopriming prior to further biotic decomposition. This study highlights the importance of litter composition and solar radiation exposure in our understanding of how decomposition patterns contribute to global C cycling.

Estimating the potential distribution of yellow spotted stink bug (Erthesina fullo) using ecological niche models

AbstractInvasive insect species threaten the productivity of ecosystems worldwide, and ecological niche models can be used to predict distributions of invaders and guide management efforts. Ecological niche models can also aid monitoring for invasive species that are globally distributed. One such species is the yellow spotted stink bug (Erthesina fullo Thunberg), a polyphagous pest native to Asia that has established in Europe and South America and threatens specialty crops. Here, we used ecological niche models to predict the potential distribution of E. fullo, and created a website to display predictions. We show that E. fullo has peak occurrence probability in areas with annual mean temperatures around 20°C, and that the occurrence probability increases as maximum monthly temperature reaches up to 38°C. The likelihood of occurrence decreased as annual precipitation increased, but increased with greater precipitation in the wettest and driest months. This suggests E. fullo is most suited to regions that are warm and dry and where most precipitation occurs across only a few months, such as southern North America, central and southern South America, southern Europe, southern Africa, and central and eastern Australia. Given that E. fullo is a highly mobile hitchhiking insect that travels through cargo and other containers to new areas, the potential spread of this species into new regions should be carefully monitored.

FC26: What have staff got to do with it? Untangling complex relationships between residential aged care staff, the quality of care they provide, and the quality of life of people with dementia

Background:Despite the integral role long term residential care staff play in the lives of residents with dementia, the mechanisms for supporting staff to bring about good quality of care (QOC) and quality of life (QOL) are poorly understood. This study focused on establishing the key mechanisms to improve QOC and in turn QOL of residents with dementia.Method:Over a 10-month period we followed: 247 older adults with dementia from 12 not-for-profit residential care facilities, their families/care partners (n=225), managers (n=12) and staff (n=232). Facilities ranged in size from 10 to 137 beds, located across remote, rural and metropolitan areas of south eastern Australia. Measures included: staff surveys, family member and resident interviews, resident file audits, live resident and staff observations and organisational audits. Multilevel Modelling or Generalised Estimating Equations analyses were conducted for each of the 12 QOC variables, with 22 staff and control variables as the predictors, and for each of the 11 QOL variables, with 20 QOC and control variables as predictors.Results:Analyses established significant associations between a large number of staff and QOC variables and between QOC and QOL variables.Conclusions:The quality of the care provided to residents has strong, widespread influences on the QOL of residents. The most promising areas for intervening with staff were: increasing the relevance and applicability of staff training and qualifications, upskilling staff in empathic care provision, communication, and restraint reduction, using a mixture of permanent and rotating shifts, prioritising recreational activity provision by all staff and increasing assistance with meals. patients with cognitive impairment in rural hospitals.

Can agronomic options alleviate the risk of compound drought-heat events during the wheat flowering period in southeastern Australia?

The impacts of compound drought-heat (DH) events on crops are more devastating than a single extreme event of drought or heat. Previous studies mainly assessed the change of individual extreme climate events. However, studies quantifying the characteristics of DH events during crop growth periods are still lacking. To the best of our knowledge, there is no study that has quantified the potential of adjusting sowing time and changing cultivars to reduce the risk of DH events for wheat in Australia. We aimed to (1) develop a combined index to capture the DH events occurring during the wheat flowering period at six study sites in southeastern Australia’s wheat belt; (2) quantify the changes in the frequency (DHF), duration (DHD), and intensity (DHI) of DH events under future climate; and (3) identify feasible agronomic options to reduce the risk of DH events. We used the APSIM model driven by climate projections from 27 GCMs for the period of 1981–2100 to simulate the wheat flowering time and daily plant available water (PAW) at 0–100 cm soil layer. The wheat sensitive period (WSP) was defined as the period from 2 weeks before flowering to 2 weeks after flowering time. A DH event occurs when the daily maximum temperature is higher than 28 ℃ and daily PAW is less than 40% of plant available water capacity for three consecutive days or more. Then, we assessed the DHF, DHD, and DHI under projected climate change. Finally, we investigated the potential of changing sowing time and cultivars to alleviate DHF, DHD, and DHI under different climate scenarios. According to the average values across six sites, the DHF, DHD, and DHI during the WSP increased by 15%, 12%, and 0.9% in 2040 s, and 49%, 44%, and 5% in 2080 s, respectively, compared to 2000 s. Such increases in DH events were mainly due to enhanced heat events. Early sowing and planting better-performing wheat cultivars with early flowering had great potential to lower the risk of future DH events. They could reduce the DHF, DHD, and DHI by 15%− 100%, 18%− 100%, and 16%− 100%, respectively, compared to without adaptation options. However, the strategy may introduce an increased frost risk across six sites, especially in regions with climates that are less dry and hot, such as Mudgee and Wagga Wagga. We expect our modelling work can provide useful information for developing effective agronomic management practices to help Australian wheat growers better prepare for DH events under climate change. The newly proposed DH framework can be applied to other dryland wheat growing regions globally.

Environmental variables influence patterns of mammal co-occurrence following introduced predator control.

Co-occurring species often overlap in their use of resources and can interact in complex ways. However, shifts in environmental conditions or resource availability can lead to changes in patterns of species co-occurrence, which may be exacerbated by global escalation of human disturbances to ecosystems, including conservation-directed interventions. We investigated the relative abundance and co-occurrence of two naturally sympatric mammal species following two forms of environmental disturbance: wildfire and introduced predator control. Using 14 years of abundance data from repeat surveys at long-term monitoring sites in south-eastern Australia, we examined the association between a marsupial, the common brushtail possum Trichosurus vulpecula, and a co-occurring native rodent, the bush rat Rattus fuscipes. We asked: In a fox-controlled environment, are the abundances of common brushtail possums and bush rats affected by environmental disturbance and each other's presence? Using Bayesian regression models, we tested hypotheses that the abundance of each species would vary with changes in environmental and disturbance variables, and that the negative association between bush rats and common brushtail possums was stronger than the association between bush rats and disturbance. Our analyses revealed that bush rat abundance varied greatly in relation to environmental and disturbance variables, whereas common brushtail possums showed relatively limited variation in response to the same variables. There was a negative association between common brushtail possums and bush rats, but this association was weaker than the initial decline and subsequent recovery of bush rats in response to wildfires. Using co-occurrence analysis, we can infer negative relationships in abundance between co-occurring species, but to understand the impacts of such associations, and plan appropriate conservation measures, we require more information on interactions between the species and environmental variables. Co-occurrence can be a powerful and novel method to diagnose threats to communities and understand changes in ecosystem dynamics.

Fox control and fire influence the occurrence of invasive predators and threatened native prey

AbstractIt can be challenging to distinguish management impacts from other population drivers, including ‘natural’ processes and co-occurring threats. However, disentangling processes is important, particularly when management may have unintended consequences, such as mesopredator release. We explored the effects of long-term, broadscale poison-baiting programs on the distribution of red foxes Vulpes vulpes (targeted invasive predator), feral cats Felis catus (unmanaged invasive competitor) and two of their threatened native prey in two fire-affected regions of south-eastern Australia. We synthesised data from 3667 camera-trap deployments at 1232 sites (172,052 trap-nights), combining experimental manipulation of foxes and fire with space-for-time approaches. Fox control effectiveness—in terms of decreased probability of fox occurrence and increased probability of prey occurrence—depended on the duration and intensity of the poison-baiting program. The effects of fox control on prey occurrence also varied between the two native prey species: fox control was strongly beneficial to the long-nosed potoroo Potorous tridactylus but had no measurable effect on southern brown bandicoot Isoodon obesulus occurrence. Feral cat occupancy tended to be higher in landscapes with long-term fox control, although we found no effect of fox-bait density on fine-scale cat occurrence. Time since fire (0–80 years) was associated with the occurrence of each study species, but its association with invasive predators also differed among vegetation types. Invasive predators and altered fire regimes are key, often overlapping, biodiversity threats. Our work highlights the importance of fine-scale monitoring and consideration of multiple drivers in distribution models to develop effective, tailored conservation strategies.

Fruit Thinning Improves Fruit Size, Yield and Return Flowering in ‘Washington Navel’ Orange (Citrus sinensis L. Osbeck)

ABSTRACT “Washington Navel” orange is the principal mid-season maturing cultivar grown in south-eastern Australia. The cultivar has strong export potential and earns high returns for citrus growers. However, trees bear a large number of small-sized fruit in an on-year followed by a small number of large-sized fruit the next year if crop load is not properly managed. Thinning can be used as a crop management strategy to adjust crop load. A thinning experiment was conducted, and crop loads were adjusted on a whole tree basis to 2, 4, 6 or 8 fruit/0.125 m3 canopy volume (CV), removing 46%, 30%, 20% and 8% of the crop respectively, and compared to non-thinned control trees. Fruit diameter was measured at regular intervals from February to July. Fruit yield and number were recorded for two consecutive seasons. Return bloom after thinning was also recorded. Thinning treatments 2, 4 and 6 fruit/0.125 m3 CV resulted in higher fruit growth rates of 24%, 9% and 14% compared to the control. Thinning to a crop load of 6 fruit/0.125 m3 CV produced the best results for fruit size and yield during the treatment year. The following year return bloom was increased in the 2, 4 and 6 fruit/0.125 m3 CV compared to the control. The 6 fruit/0.125 m3 CV treatment resulted in a higher cumulative yield of 169 kg/tree over two cropping seasons and 42% fruit in the size class > 75 mm diameter compared to the control. Economic analysis revealed that 6 fruit/0.125 m3 CV could generate an extra $4,240/ha of income for citrus growers. It was concluded that a fruit load of 6 fruit/0.125 m3 CV was required to produce high yields and large fruit size over two cropping seasons.

The influence of weathering processes on microtopographic changes of sandstone under simulated upper intertidal conditions from hourly to weekly scales

Micro-scale surface changes of bedrock on shore platform have been monitored with micro-erosion meters (MEMs) and show significant downwearing over several (≥2) years. At short-term temporal scale of hours to days, rock surface behaviors are reversible and do not generate net surface lowering. Therefore, there is a temporal gap between the two temporal scales of surface behaviors over which grain detachment must occur. In this study, an upper intertidal zone (2-h immersion with subsequent 2-week exposure) was simulated in the laboratory to investigate the fast erosion rate at high elevation identified from the Otway coast in south-eastern Australia using MEMs.During the experiments, the microtopography of rock surface was monitored 2-hourly during the daytime period (0−12 h) on Day 1 (beginning), 8 (middle) and 14 (end) of the 14-day simulation to understand the cumulative effect of short-term surface changes on rock weathering and erosion at longer timescales in order to provide insights into the role of rock surface dynamics in shore platform evolution. Through manipulation of the salt content of water as well as temperature and humidity in the controlled measures, the experiment was also designed to test the primary weathering process in driving short-term surface changes at this particular tide level. Results show the primary role of temperature-induced salt crystal volume change in generating the short-term rock surface movements on high tidal to supratidal rock. Although the cumulative effect of short-term surface behaviors on rock microtopography appeared to be observed over longer timescales, it still remains uncertain if this drives rock decay at the weekly scale. Future studies are required to monitor the rock surface over a sufficiently long period (up to months) to determine the temporal threshold of erosion and understand the linkage between short-term surface changes and rock decay.

What Do We Know About Threshing Traditional Grains in Australia?

This article reviews ethnographic descriptions of Australia's First Nations people's grain threshing to inform future grain research and revival of practice in south-eastern Australia. The processing of grain requires many steps, and while harvesting, winnowing and grinding are comparatively well-documented, the threshing stage, which involves the removal of the husk and other nonedible parts of the seed head before the seed is winnowed and ground, remains poorly understood. In south-eastern Australia much of the threshing knowledge has been lost through the impacts of colonization; whereas communities in Central Australia have retained this knowledge in relation to their traditional grains. However, these species are not common in all areas. As different species require different threshing processes, only some of this knowledge can be directly applied in south-eastern Australia. Ethnographic descriptions have the potential to contribute additional First Nations knowledge to the revitalization of this practice. This article brings together ethnographic descriptions of traditional threshing to facilitate the revival of practice and further native grains research.

Gut Microbiome Profiling of the Endangered Southern Greater Glider (Petauroides volans) after the 2019-2020 Australian Megafire.

Studying the gut microbiome can provide valuable insights into animal health and inform the conservation management of threatened wildlife. Gut microbiota play important roles in regulating mammalian host physiology, including digestion, energy metabolism and immunity. Dysbiosis can impair such physiological processes and compromise host health, so it is essential that the gut microbiome be considered in conservation planning. The southern greater glider (Petauroides volans) is an endangered arboreal marsupial that faced widespread habitat fragmentation and population declines following the 2019-2020 Australian bushfire season. This study details baseline data on the gut microbiome of this species. The V3-V4 region of the 16S rRNA gene was amplified from scats collected from individuals inhabiting burnt and unburnt sites across southeastern Australia and sequenced to determine bacterial community composition. Southern greater glider gut microbiomes were characterised by high relative abundances of Firmicutes and Bacteroidota, which is consistent with that reported for other marsupial herbivores. Significant differences in gut microbial diversity and community structure were detected among individuals from different geographic locations. Certain microbiota and functional orthologues were also found to be significantly differentially abundant between locations. The role of wildfire in shaping southern greater glider gut microbiomes was shown, with some significant differences in the diversity and abundance of microbiota detected between burnt and unburnt sites. Overall, this study details the first data on greater glider (Petauroides) gut microbiomes, laying the foundation for future studies to further explore relationships between microbial community structure, environmental stressors and host health.

AusLAMP shines a light on space weather hazards in the Australian high-voltage power grid

A geomagnetic storm, also known as a geomagnetic disturbance (GMD), is a major disturbance of the Earth’s magnetic field caused by solar activity. A geomagnetic storm induces electric currents in the Earth that feed into power lines through substation neutral earthing, causing instabilities and even blackouts in electricity transmission systems. The intensity of geomagnetically induced currents (GICs) is closely associated with the electrical conductivity of the surrounding geology. In this paper, we analyse one of the most well-known geomagnetic storms, the 1989 “Québec storm” and 688 magnetotelluric (MT) survey sites from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) to gain insight into the space weather hazard posed for Australia's modern-day power grids. Transmission lines may exhibit local maxima at differing times depending on their spatial orientation and length with respect to the time-varying magnetic field. Localised peak voltages over 100 V can be observed on some individual lines. This assessment identifies the distribution of GICs in south-eastern Australia for the 1989 Québec storm and transmission lines that are more vulnerable to GICs. It is relevant to national strategies and risk assessment procedures to mitigate space weather hazards in the Australian high-voltage power grid and the design of a more resilient power transmission system. We also analyse the 2015 “St Patrick’s Day storm” to study under-estimation of the space weather hazard associated with the band-limited geomagnetic data and MT data sets. Key points The subsurface geology has a great influence on the intensity of geomagnetically induced electric fields, potentially causing up to three orders of magnitude difference between conductive basins and resistive cratonic regions in south-eastern Australia. Analysis using the 1989 “Québec geomagnetic storm” and AusLAMP magnetotelluric data shows the intensity of the geoelectric fields in south-eastern Australia could reach up to 5 [V/km]. Geomagnetically induced voltages in the Australian high-voltage power grid could be in excess of 100 V in some transmission lines for a geomagnetic storm with intensity comparable with the 1989 Québec geomagnetic storm.