Southern Australia Research Articles

Exploring chemical control of 2,4-D–resistant wild radish (Raphanus raphanistrum) with auxin-related compounds

AbstractSynthetic auxin herbicides were developed and commercialized 60 yr before their mode of action was definitively elucidated. Although evolution of resistance to auxinic herbicides proceeded more slowly than for some other herbicide chemistries, it has become a major problem in the dicotyledonous weeds of many cropping areas of the world. With the molecular characterization of the auxin perception and signaling pathway in the mid-2000s came a greater understanding of how auxinic herbicides work, and how resistance may develop in weeds subjected to repeated selection with these herbicides. In wild radish (Raphanus raphanistrum L.) populations in southern Australia, resistance to multiple herbicides, including synthetic auxins such as 2,4-D, has reduced the number of chemical control options available. The aim of this study was to determine whether compounds involved in auxin biosynthesis, transport, and signaling are able to synergize with 2,4-D and increase its ability to control 2,4-D–resistant R. raphanistrum populations. Although some mild synergism was observed with a few compounds (abscisic acid, cyclanilide, tryptamine), the response was not large or consistent enough to warrant further study. Similarly, alternative auxinic herbicides applied pre- or postemergence were no more effective than 2,4-D. Therefore, while use of auxinic herbicides continues to increase due to the adoption of transgenic resistant crops, nonchemical control techniques will become more important, and chemical control of 2,4-D–resistant R. raphanistrum should be undertaken with alternative modes of action, using mixtures and good stewardship to delay the development of resistance for as long as possible.

Early-melting snowpatch plant communities are transitioning into novel states

Snowpatch plant community distribution and composition are strongly tied to the duration of long-lasting snow cover in alpine areas; they are vulnerable to global climatic changes that result in warmer temperatures and longer growing seasons. We used a revisitation study to quantify early-melting snowpatch floristic and functional diversity change in southern Australia, and document shrub size-class distributions over time to detect evidence for their encroachment into snowpatches, a key prediction with climatic change. Early-melting snowpatch vegetation has declined in areal extent, changed in species composition, and shrub and tussock grass cover has increased, but changes in functional trait diversity were less clear. Species gains, particularly by non-clonal species, accounted for most of the floristic change observed. Shrub recruitment was ongoing by most shrub species. Biotic differentiation is occurring; many early-melting snowpatches are transitioning to a novel state with changed composition and taller vegetation structure, but there is little evidence for species loss having occurred. Given enough time, however, the long-term loss of species is likely (i.e. biotic homogenisation) if taller shrubs outcompete short-statured snowpatch species. Our results provide evidence that this alpine ecosystem is forming a novel community with an uncertain future.

Multiweek Prediction and Attribution of the Black Saturday Heatwave Event in Southeast Australia

Abstract Southeastern Australia experienced an extreme heatwave event from 27 January to 8 February 2009, which culminated in the devastating “Black Saturday” bushfires that led to hundreds of human casualties and major economic losses in the state of Victoria. This study investigates the causes of the heatwave event, its prediction, and the role of anthropogenic climate change using a dynamical subseasonal-to-seasonal (S2S) forecast system. We show that the intense positive temperature anomalies over southeastern Australia were associated with the persistent high pressure system over the Tasman Sea and a low pressure anomaly over southern Australia, which favored horizontal warm-air advection from the lower latitudes to the region. Enhanced convection over the tropical western Pacific and northern Australia due to weak La Niña conditions appear to have played a role in strengthening the high pressure anomalies over the Tasman Sea. The observed climate conditions are largely reproduced in the hindcast of the Australian Community Climate and Earth System Simulator–Seasonal prediction system version 1 (ACCESS-S1). The model skillfully predicts the spatial characteristics and relative intensity of the heatwave event at a 10-day lead time. A climate attribution forecast experiment with low atmospheric CO2 and counterfactual cold ocean–atmospheric initial conditions suggests that the enhanced greenhouse effect contributed about 3°C warming of the predicted event. This study provides an example of how a S2S prediction system can be used not only for multiweek prediction of an extreme event and its climate drivers, but also for the attribution to anthropogenic climate change.

Seedling emergence of tropical perennial pasture species in response to temperature used to determine sowing time recommendations

Tropical pasture grasses and legumes can be highly productive and persistent and fill the summer-autumn feed gap typical of temperate pasture systems in southern Australia. However, more information is needed on optimum temperature range for seedling emergence because this will influence sowing time recommendations. A replicated field experiment was conducted at 5 locations in New South Wales over a 12-month period to determine the optimum temperature for emergence of a range of tropical species: Rhodes grass (Chloris gayana Kunth), Makarikari grass (Panicum coloratum L. var. makarikariense Gooss.), kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone), digit grass (Digitaria eriantha Steud.), panic grass (Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs), paspalum (Paspalum dilatatum Poir.), Urochloa hybrid (Urochloa decumbens × U. ruziziensis × U. brizantha), 2 cultivars of Desmanthus virgatus (L.) Willd. (cultivars ‘Marc’ and ‘JCU2’), D. bicornutus (S. Watson), D. leptophyllus (Kunth) and D. pernambucanus (L.) Thell.). Rhodes grass emerged satisfactorily over the longest time across all sites, exhibiting the greatest temperature range over which emergence occurred, while Makarikari grass and panic grass had the narrowest temperature range for emergence. The temperature for 50% emergence differed between the tropical species and whether the soils were warming or cooling. Rhodes grass had the lowest 50% emergence temperature (17 °C) while paspalum had the highest (22 °C). Results showed that temperature for 50% emergence is a useful indicator for determining sowing time in warming soils.

Intercropping—Towards an Understanding of the Productivity and Profitability of Dryland Crop Mixtures in Southern Australia

Intercropping using mixtures of dryland crop species for grain or seed production was investigated in southern Australia across a range of rainfall zones over three years. The objective was to understand the productivity and profitability of intercropping in extensive, high-input grain cropping systems. Previous research has shown large productivity benefits of mixtures; however, few farmers practice intercropping in Australia, and an analysis of profitability is needed to support future potential adoption. Experimental results showed strong mixture responses (in terms of yield, value and land equivalence), but not all were profitable compared to an equivalent share of monoculture crops (as measured by gross margins). The most promising mixtures were those containing high-value crops (canola) and legumes (field pea or faba bean) at the wetter sites where the additional gross margin over equivalent monoculture crops ranged from $12/ha to $576/ha. Mixtures containing highly competitive crops (wheat or barley) were generally unprofitable. Mixtures involving cereals were doubly disadvantaged by the aggressiveness of these lower-value crops in the mixtures we examined and the high grain separation costs post-harvest. Cost reduction in mixture systems involving high-value crops that are synergistic (grain legumes) should provide enduring opportunities for intercropping in southern Australia.

Records of leopard seals Hydrurga leptonyx ashore in South Australia, 2017–2022

The leopard seal Hydrurga leptonyx is one of five phocid species with a circumpolar distribution in the Southern Ocean. They do not breed on the Australian coast. We document records of 14 leopard seals (two collected specimens, 12 live sightings) in South Australia (SA) between November 2017 and November 2022, from Fowlers Bay to the mouth of the River Murray. We used records from the SA Museum, reports from coastal officers of SA Department for Environment and Water, and information from the public. All 14 seals were juvenile and most were in fair/thin body condition. Two collected specimens and two sighted animals showed evidence of blunt trauma. Stomachs contained fish remains and feathers, and one contained 21 semi-digested smooth toadfish Tetractenos glaber, a species which contains the toxin tetrodotoxin. Necropsies on two specimens involved gross, histopathological, and diagnostic assessment of pathogens, organs, and skin lesions. All records were between June and December, similar to the seasonal distribution reported previously in southern Australia. The 14 records over 5 years to 2022 averaged 2.8 per year, higher than during a previous study in SA that ran over three decades to October 2009 at 1.2 per year.

How sensitive are catchment runoff estimates to on-farm storages under current and future climates?

Storage of water in farm dams is important to support irrigation, stock requirements and domestic uses when reticulated water is unavailable. Farm dams that fill by intercepting landscape runoff change the total volume and seasonality of catchment streamflow, potentially impacting water policy outcomes. While numerous studies have quantified how climate change and farm dams independently change streamflow characteristics, few studies have investigated their interactions. This study investigates the interactions between farm dams and climate change in the Murray-Darling Basin of southern and eastern Australia. We use hydrological modelling that explicitly represent farm dams and remotely sensed data describing historical farm dam development to assess the impacts of farm dams for 112 catchments on catchment runoff under current and future climates. Our analysis compares current and future runoff estimates to those derived without explicitly incorporating farm dam impacts to better understand the importance of farm dams in water resources assessments.We find that modelling farm dams in these catchments improves the performance of the hydrological model relative to a traditional rainfall-runoff model ignoring the effects of farm dams. The current level of farm dam development in the Murray-Darling Basin is estimated to reduce annual catchment runoff by 13% (in the range of 8%–19%) under the historical climate across the 112 catchments investigated here. We find that explicitly modelling farm dams increases the sensitivity of simulated streamflow to climate by approximately 10%. This is primarily because farm dams introduce additional catchment storage and water extractions that do not directly follow processes represented in traditional rainfall-runoff models.Our analysis offers important information for water policymakers in Australia and globally. Firstly, explicit modelling of farm dams is critical to understanding the future availability of water resources. Secondly, explicit modelling of farm dams allows their impacts on catchment runoff to be explored under current and future climates, and for policies to manage the impacts of dams to be investigated.

Exploiting asynchronous host-parasitoid emergence distributions to optimise insecticide applications and protect beneficial insects– a case study using the citrus gall wasp Bruchophagus fellis (Hymenoptera: Eurytomidae)

The citrus gall wasp (CGW), Bruchophagus fellis (Girault) (Hymenoptera: Eurytomidae), is a serious pest of citrus in southern Australia. Severe infestations can result in yield loss and a reduction in fruit size. Several parasitoid species attack CGW, with Megastigmus brevivalvus (Girault) (Hymenoptera: Torymidae) (MBV) being the dominant species. Both CGW and MBV are univoltine and adult wasps emerge from galls in the spring. Median emergence of MBV lags behind that of CGW by 2–3 weeks. We modelled the effect of spray timing for foliar-applied, non-systemic insecticides on the relative exposures of CGW and MBV based on their emergence distributions and estimated the optimal spray timing that maximises the control of CGW while minimising the impact on MBV. Three temporal emergence distribution scenarios for the two species and 28 periods of residual insecticide activity were considered in the investigation. The results showed that the optimal spray timing was always before the peak emergence of CGW. Depending on the residual activity of the insecticide, the optimal spray date pre-dated the peak emergence of CGW by 1–24 days, with longer lead times for insecticides with longer residual activity. By contrast, the optimal spray date varied little across the different emergence scenarios, suggesting that the results apply over a wide range of locations and seasons. A single insecticide application at the optimal timing may not guarantee satisfactory control of CGW. When the residual activity of the insecticide is short, multiple applications with a combined residual activity of 16 days are needed to ensure insecticide contact with ≥90% of all CGW that emerge in a season.

Camera-based automated monitoring of flying insects in the wild (Camfi). II. flight behaviour and long-term population monitoring of migratory Bogong moths in Alpine Australia.

The Bogong moth Agrotis infusa is well known for its remarkable annual round-trip migration from its breeding grounds across eastern and southern Australia to its aestivation sites in the Australian Alps, to which it provides an important annual influx of nutrients. Over recent years, we have benefited from a growing understanding of the navigational abilities of the Bogong moth. Meanwhile, the population of Bogong moths has been shrinking. Recently, the ecologically and culturally important Bogong moth was listed as endangered by the IUCN Red List, and the establishment of a program for long-term monitoring of its population has been identified as critical for its conservation. Here, we present the results of two years of monitoring of the Bogong moth population in the Australian Alps using recently developed methods for automated wildlife-camera monitoring of flying insects, named Camfi. While in the Alps, some moths emerge from the caves in the evening to undertake seemingly random flights, filling the air with densities in the dozens per cubic metre. The purpose of these flights is unknown, but they may serve an important role in Bogong moth navigation. We found that these evening flights occur throughout summer and are modulated by daily weather factors. We present a simple heuristic model of the arrival to and departure from aestivation sites by Bogong moths, and confirm results obtained from fox-scat surveys which found that aestivating Bogong moths occupy higher elevations as the summer progresses. Moreover, by placing cameras along two elevational transects below the summit of Mt. Kosciuszko, we found that evening flights were not random, but were systematically oriented in directions relative to the azimuth of the summit of the mountain. Finally, we present the first recorded observations of the impact of bushfire smoke on aestivating Bogong moths - a dramatic reduction in the size of a cluster of aestivating Bogong moths during the fire, and evidence of a large departure from the fire-affected area the day after the fire. Our results highlight the challenges of monitoring Bogong moths in the wild and support the continued use of automated camera-based methods for that purpose.

Point mutations including a novel Pro-197-Phe mutation confer cross resistance to acetolactate synthase (ALS) inhibiting herbicides in Lactuca serriola in Australia.

Control of prickly lettuce has become increasingly difficult for lentil growers in southern Australia due to widespread resistance to common herbicides, a lack of alternative herbicide options, and prolific production of highly mobile seed. This study aimed to quantify ALS-inhibiting herbicide resistance in the Mid North (MN) and Yorke Peninsula (YP) of South Australia, characterise the resistance mutations present, and investigate population structure and gene flow in this species. Resistance was identified in all populations tested, with average survival of 92% to chlorsulfuron and 95% to imazamox + imazapyr. Five different amino acid substitutions were identified at Proline-197 of the ALS gene. There was no significant difference in the LD50 between plants with these five different substitutions when treated with metsulfuron-methyl, however, imidazolinone resistance level was higher in plants with a phenylalanine substitution and lower in plants with a serine. Population structure based on 701 SNPs and 271 individuals provided evidence for both the independent evolution of the same mutation in different populations, as well as frequent short to medium distance dispersal accompanied by occasional long-distance dispersal events. The overall inbreeding coefficient (FIS ) was calculated at 0.5174, indicating an intermediate level of outcrossing despite the cross-pollination experiment showing only low outcrossing. In the structure analyses, most individuals from YP were assigned to a single cluster, whereas most individuals from MN were assigned 50% to each of two clusters, indicating some genetic differences between these two regions, but also evidence for dispersal between them. Use of imidazolinone herbicides has selected for mutations conferring higher levels of resistance, such as the Pro-197-Phe mutation, and resulted in further spread of resistance in this species. This article is protected by copyright. All rights reserved.

Venomius, a new monotypic genus of Australian orb-weaving spiders (Araneae, Araneidae)

A new monotypic Australian genus in the orb-weaving spider family Araneidae Clerck, 1757 is described, Venomiusgen. nov., with V. tomhardyisp. nov. as type species. Somatically, Venomiusgen. nov. is similar to the typical leaf-curling orb-weaving spiders, such as Phonognatha Simon, 1894 or Leviana Framenau & Kuntner, 2022, due to a similar elongate cylindrical abdomen and colouration; however, the genital morphology of the new genus is very different. Most unusual are the presence of two strong macrosetae on the male pedipalp tibia. Male pedipalp sclerites are complex, with diagnostic characters including the tibial macrosetae and a keeled median and a rounded basal process on the stipes. The epigyne of females is wholly covered by the scape that has a short median process. Venomius tomhardyigen. nov. et sp. nov. has been collected in southern Australia, from Tasmania to Western Australia, where it builds a circular, vertical orb-web. Spiders often hide in silk-lined hollows in branches of trees when disturbed during the day.

Increased impact of the El Niño–Southern Oscillation on global vegetation under future warming environment

There are broad effects of vegetation changes on regional climate, carbon budget, the water cycle, and ecosystems’ productivity. Therefore, further knowledge of the drivers of future vegetation changes is critical to mitigate the influences of global warming. The El Niño–Southern Oscillation (ENSO) is a major mode of interannual climate variability and is likely to affect vegetation on the global scale. Nonetheless, little is known about the causal impacts of ENSO on future vegetation cover with changes in land use and a warming environment. Here, we examined the connections between ENSO and vegetation using leaf area index (LAI) data over the period 2015–2100 from Coupled Modeling Intercomparison Project Phase 6. Our findings indicate that, compared with the historical period 1915–2000, the vegetated areas influenced by ENSO are projected to rise by approximately 55.2% and 20.7% during the twenty-first century of the scenarios SSP2-4.5 and SSP5-8.5, respectively. Though uncertainty for the causal link between ENSO and vegetation changes remains in several regions (i.e., parts of North America, southern Australia, and western Asia), ENSO signature on LAI variations is robust over northern Australia, Amazonia, and parts of Southeast Asia. These results indicate that the influences of ENSO on global vegetation may strengthen in the future.

Increasing Risks of Future Compound Climate Extremes With Warming Over Global Land Masses

AbstractCompound climate extremes (here referred to compound dry–hot events and compound pluvial–hot events) result in devastating disasters which threaten water‐food‐energy security. However, in a warming scenario, the risk of occurrence, the quantification of uncertainty, and associated drivers of compound climate extremes—particularly compound pluvial–hot events—have not been fully explored. By leveraging climate model large ensembles, it is revealed that the risk of compound climate extremes is projected to increase 2–3 times over most global land masses in future Representative Concentration Pathway (RCP) 8.5 forcing compared with historical forcing. Increased risks of compound climate extremes are mainly attributed to the changes in temperature and changes in dependence between precipitation and temperature, while the change in precipitation contributing to risk of these two compound climate extremes exhibits approximately spatial complementary. In the warming world, the hot spots of compound dry–hot extremes mainly lie in Europe, South Africa, and the Amazon, while those of compound pluvial–hot extremes mostly lie in the eastern USA, eastern and southern Asia, Australia, and central Africa. These findings help stakeholders and decision makers develop a package of climate change adaptation strategies to manage and mitigate the risk of compound climate extremes.

Durability Assessment of Alkali-Activated Concrete Exposed to a Marine Environment

This study investigated the performance of two alkali-activated concretes (AACs) subjected to marine exposure for 2 years. The AACs were synthesized from a low-calcium Class F fly ash (FA) and a blast-furnace slag. Concrete specimens were exposed in a marine environment in a port facility in southern Australia for 2 years. The specimens were subject to a range of nondestructive testing (NDT) techniques, including resistivity, Schmidt hammer, and ultrasonic pulse velocity (UPV) tests. In addition, chloride diffusion coefficients were calculated from concrete cores taken from specimens exposed in the marine environment. Microscopy analysis was undertaken using Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA), and comparative data were taken on laboratory specimens at 28 days. Furthermore, the chloride diffusion coefficients were compared with the results of standard laboratory tests undertaken on the control samples at 28 days, including rapid chloride permeability testing (RCPT) using a 10-V driving voltage, an NT Build 492 test, and a bulk diffusion test, to determine the relationship between the 28-day laboratory tests results and the site performance. The data showed good correlation between the predicted performance based on the 28 day laboratory tests and the 2-year site data. The chloride diffusion of the ground granulated blast-furnace slag (GGBS) concrete agreed very accurately with the predicted value from the modified RCPT test, whereas the performance of FA concrete was superior to that predicted.

On the timing of megafaunal extinction and associated floristic consequences in Australia through the lens of functional palaeoecology

The timing and cause of megafaunal extinctions are an enduring focus of research interest and debate. Despite the developments in the analysis of coprophilous fungal spores (CFS), the proxy for reconstructing past megaherbivore changes, the environmental consequences of this fauna loss remain understudied. This is partly due to the general obscurity of such a signal in pollen records, as well as limitations in disentangling human and extinction ecological impact, and the lack of spatial information of megafauna changes in site-level sedimentary records. In Australia, the debate centres on the possibility that habitat loss through climate change, vegetation-fire change, human intervention, or a combination of these factors led to the extinction of some large animals during the Late Pleistocene. Pollen and plant isotope studies have also demonstrated that vegetation-fire responses following the Late Pleistocene megafaunal extinctions were characterized by increased vegetation density and fire activity due to reduced grazing/browsing pressure. Here, we use a well-dated marine sedimentary core record from the Murray Darling Basin in southern Australia and apply palynological and functional palaeoecological approaches to reconstruct the Late Pleistocene megafaunal abundance changes, the timing and potential cause of extinction across the basin and investigate if extinction was associated with any signal of trait-based vegetation changes. We infer megafaunal abundance changes from the abundance of CFS and compare this with climatic proxies from the same core. We then link modern observations of fruit, seed and fire response traits of plant genera within the basin to the fossil pollen record to reconstruct palaeo vegetation community traits and determine if extinction was associated with any changes in plant community trait composition. Closely-spaced 14C dates obtained from planktonic foraminifera and δ18O tie points place a major decline in CFS, and thus the timing of extinction, within the basin at ∼43.3 ka. While climate-driven environmental changes largely controlled megafaunal presence, human arrival and frequent landscape burning are considered the most likely primary cause of extinction or, at the very least, megafauna decline in the Murray Darling Basin. We also found that the proposed period of megafaunal decline was also accompanied and followed by a decline in the prevalence of plants with larger seeds and fruits that were likely to have been once dispersed by megaherbivores. Our study supports the idea of a human-driven megafaunal extinction in mainland Australia and that the extinction caused changes in vegetation due to reduced plant dispersal and herbivory. However, high fire activity primarily linked to these vegetation changes was not observed, as humans were already practicing landscape burning before the period of megafaunal extinction and likely continued to do so afterward.

Impact of Zonal and Meridional Atmospheric Flow on Surface Climate and Extremes in the Southern Hemisphere

Abstract The Southern Annular Mode (SAM) describes the annular or zonal component of the large-scale atmospheric circulation in the Southern Hemisphere (SH) extratropics and influences surface climate across the SH. Although this annular flow is dominant in austral summer, in other seasons considerable zonal asymmetries are evident, reflecting a zonal wave 3 (ZW3) pattern. We define an index representing asymmetric flow using the first two leading modes of meridional wind variability in the SH. Two orthogonal ZW3 indices are used together to capture longitudinal shifts in the wave train and their connection to tropical convection. We compare the impacts of the SAM and ZW3 on surface climate by examining composites of temperature and precipitation fields during each season. Impacts on mean and extreme surface climates are assessed. We find that the SAM and ZW3 are not clearly separated modes, but rather, ZW3 modulates the impact of the SAM across the midlatitudes. The SAM influence on regional temperature and precipitation is similar for both mean impacts and extremes. The ZW3 influence on extremes is more varied across indices and does not always reflect the ZW3 impact on mean fields. Notably, amplified ZW3 activity has a significant influence on the number of midlatitude fronts and frontal rainfall, highlighting the importance of considering ZW3 when exploring the surface climate impacts of large-scale SH circulation states, particularly for nonsummer seasons. Significance Statement Variations in the strength and position of the midlatitude westerly winds have a strong influence on surface climates. While these winds are predominantly zonally symmetric in the Southern Hemisphere, few studies to date have explored the role of the asymmetric component of this circulation, particularly for seasons outside of summer. By defining two new indices of meridional circulation, this study reveals new important impacts on temperature, rainfall, and the likelihood of extreme climates in regions of southern Australia and South America, and sea ice regions around Antarctica. These findings question the validity of considering only zonal-mean winds for climate studies of the Southern Hemisphere and have important implications for the seasonal forecasting and predictability of extreme climate events in the near future.

Stable isotopes infer the diet and habitat of the enigmatic pygmy right whale (Caperea marginata) off southern Australia

In the Southern Hemisphere, baleen whales generally undertake migrations between productive feeding grounds at high latitudes and breeding grounds at lower latitudes. Pygmy right whales (Caperea marginata) (PRW) are the smallest and most enigmatic baleen whale, that likely forgo long-distance migrations, and instead inhabit temperate and subantarctic waters year-round. Previous research has relied on limited data from sighting and stranding records to infer the habitat use and diet of PRWs, however the absence of long-term and consistent data has left uncertainty surrounding these parameters. We utilized bulk stable isotopes of carbon (δ13C) and nitrogen (δ15N) in baleen from Australian PRWs (n = 14) to infer their diet and habitat use. Stable isotope values from 1980–2019 were then matched to remote sensed data from known upwelling regions (where they likely feed) to examine if their dietary patterns are related to changes in food web dynamics. We found that PRWs remained in mid-latitude waters year-round and showed no evidence of feeding in Antarctic waters. Rather, their isotopic record suggests they remain between coastal waters off southern Australia and the Subtropical Convergence, feeding on krill and copepods. Additionally, there was a weak positive relationship between PRW nitrogen stable isotope values and sea surface temperature (SST) from the eastern Great Australian Bight (GAB) and Bonney Upwelling. This suggests seasonal changes in their diet is possibly correlated to oceanographic changes which drive food-web dynamics in these regions. Unlike larger species of baleen whales that migrate further to highly productive waters in the Southern Ocean to meet their energetic demands, the small PRW, who only reach 6.5m, may sustain both feeding and breeding requirements at mid-latitudes. This is the first study to analyze long-term dietary and movement patterns of the PRW, providing an important contribution to our understanding of the species.

Hydrological change in southern Australia over 1750 years: a bivalve oxygen isotope record from the Coorong Lagoon

Abstract. Multi-centennial records of past hydroclimate change are essential for understanding the resilience of ecosystems to climatic events in addition to guiding conservation and restoration efforts. Such data are also crucial for examining the long-term controls over regional hydroclimate and the inherent variability in extreme droughts and floods. Here, we present a 1750-year record of hydroclimate variability in the Coorong South Lagoon, South Australia, part of an internationally significant wetland system at the mouth of Australia's largest river, the Murray River. Oxygen isotope ratios were measured from Arthritica helmsi bivalve shells preserved in sediments. The oxygen isotope record shows periods of persistent low and high moisture balance, from ∼500 to 1050 years and from ∼1300 to 1800 years, respectively, which is consistent with other hydroclimate reconstructions from the region. The range of oxygen isotope values in the sedimentary shells does not differ significantly from the estimated range of modern specimens from the present-day lagoon. These data suggest that the restricted and highly evaporated modern-day conditions are not markedly different to the pre-impacted state over the last 1750 years, although the absence of A. helmsi in the contemporary lagoon is likely a response to increased salinity, nutrient loading, and anoxia during the last century. These insights are potentially useful both in guiding management efforts to conserve and restore the Coorong Lagoon and for understanding long-term water resource availability in the region.

Choose Local: Dung Addition from Native Herbivores Can Produce Substantial Positive Effects on the Growth of Native Grasses Compared to Livestock Dung

Livestock grazing and dung deposition can increase soil nutrients, contributing to the dominance of exotic species. Recent research suggests that native herbivore grazing has positive effects on native vegetation and soil health. However, little is known about the effects of native herbivore dung on plant growth and its potential implications for the restoration of degraded grasslands. This study examined the effects of dung addition from a native herbivore, kangaroo (Macropus giganteus), and ruminant livestock, sheep (Ovis aries), on biomass production and nutrient uptake of the native perennial wallaby grass (Rytidosperma auriculatum) and the annual exotic wild oat (Avena barbata), two of the most abundant grasses from the temperate grasslands of southern Australia. We conducted a glasshouse experiment, adding each type of dung to each plant species grown without competition in pots containing soil with a nutrient composition similar to that of old fields. Kangaroo dung produced higher wallaby grass aboveground biomass than other treatments and less wild oat aboveground biomass than the control. Kangaroo dung affected nutrient uptake but not nutrient concentration. Sheep dung had no effect. We demonstrated that native herbivores and livestock dung can have different effects on the biomass of native and invasive grasses. The higher nutrient uptake in wallaby grass appeared to be a consequence of the higher biomass production, suggesting that the effects produced by kangaroo dung could be related to its chemical and biological characteristics rather than its nutrient composition. Incorporating native herbivores’ dung or facilitating their presence can improve restoration outcomes in degraded grasslands.

The beautiful noctuid moth Chasmina pulchra (Doubleday) (Lepidoptera: Noctuidae) is a highly dispersive species, now established on urban kurrajongs Brachychiton populneus in southern Australia

ABSTRACT We report the establishment of the beautiful noctuid moth Chasmina pulchra in southern Australia following repeated self-introduction. First recorded in 1955 as a vagrant in suburban Adelaide, specimens have been collected or observed at an increasing rate since then. We have recently located a breeding population on the Adelaide Plains where the larvae feed on the introduced kurrajong tree Brachychiton populneus (Malvaceae), although other Brachychiton species are likely to be exploited elsewhere in its range. Native to the drier parts of eastern Australia, this drought-tolerant tree has been widely grown as a specimen or amenity tree in suburban Adelaide since the mid-nineteenth century. Chasmina pulchra appears to have an annual life cycle in South Australia, with adult moths active in the summer, December – March. Larvae cause characteristic scalloping on the leaf margins of the food plant. We present evidence that this tropical to subtropical native species has expanded its range into the southern half of the continent in the last few decades. We also report the first specimen collected in northern Tasmania, associated with a weather system that could have facilitated its movement across Bass Strait. Southward incursions are associated with both wetter and drier than average monthly rainfall totals just prior to the event. Together with recent records from southwestern Australia well beyond the natural range of a putative food plant, we conclude that C. pulchra is a highly dispersive species, behaviour consistent with at least one other species of Chasmina in the Old World.