Publications
Late-Holocene palaeoecological reconstruction of Southern Hemisphere Westerlies variability on Subantarctic Macquarie Island
A detailed reconstruction of Southern Hemisphere Westerlies (SHW) variability over the last 2500 years on Macquarie Island reveals periods of strengthened and weakened westerly winds, linked to changes in sea spray-driven lake conductivity. The study found that stronger SHW occurred around ~2500–2300 cal. yr BP and after ~800 cal. yr BP, while weaker SHW prevailed between ~2300–800 cal. yr BP. These findings were derived from palaeoecological analysis of halophilic and halophobic diatoms preserved in lake sediments, which correlate with water conductivity gradients influenced by westerly winds. The study provides a critical long-term record of SHW behavior, offering insights into past atmospheric CO2 concentrations and Southern Hemisphere climate dynamics.
A Novel Invertebrate Predator on an Oceanic Island: Impacts and Invasion Dynamics of Kontikia andersoni on Macquarie Island
Invasive flatworms Kontikia andersoni significantly reduce invertebrate richness at higher elevations on Macquarie Island, threatening native biodiversity. Researchers analyzed species co-occurrence data and community composition across multiple sites, revealing that slope and wind speed are key factors influencing the flatworm's distribution. Habitat suitability modeling identified high-risk areas for invasion, offering critical targets for biosecurity surveillance. This study provides new insights into the ecological impacts of K. andersoni and supports conservation efforts to protect Macquarie Island's fragile ecosystems.
Seasonal and decadal changes in seabird abundance in inshore waters at subantarctic Macquarie Island
Land-based surveys at Macquarie Island reveal significant inter-annual variation in the diversity and abundance of non-breeding seabirds visiting inshore waters, with notable increases in breeding petrel populations following invasive species eradication. The study, comparing data from 2017–2018 and 2022–2023 against a baseline of 2002–2003, documented 41 out of 43 seabird species observed during the baseline period. Nocturnal spotlight surveys also uncovered the first mainland colonies of Common Diving-petrels on Macquarie Island and provided circumstantial evidence for storm-petrel recolonization. While less reliable for detecting changes in penguin abundance or smaller seabirds like prions, diving-petrels, and storm-petrels, these surveys offer valuable insights for marine spatial planning and regional environmental trend monitoring, complementing established on-island studies.
The ongoing decrease in numbers of breeding female southern elephant seals ( Mirounga leonina L.) at Macquarie Island
Southern elephant seal populations at Macquarie Island are uniquely declining, unlike other global populations that remain stable or grow. A 78-year study reveals a steady annual decrease of ~1.1% in breeding females on the isthmus—representing about 20% of the total population—from approximately 9,400 in 1949 to 2,550 in 2023. Annual data since 1984 confirms a similar trend (~0.8% decline), despite interannual variability likely due to breeding skips rather than counting errors. While summer ocean conditions (proxied by the Southern Annular Mode) show no direct link, winter prey dynamics remain the suspected driver of this ongoing decline. The study leverages long-term monitoring and statistical correlation to assess population trends and conservation status.
Derivation of site-specific environmental quality guideline values for fuel-contaminated soils on sub-Antarctic Macquarie Island
Scientists have established the first environmental quality guideline values (EQGVs) for fuel-contaminated soils on sub-Antarctic Macquarie Island, a critical step in protecting its unique ecosystem. Using a species sensitivity distribution model, researchers derived a protective concentration (PC80) of 97 mg/kg total petroleum hydrocarbons (TPH C9–C40), suitable for the immediate station area, and more conservative values for higher conservation zones. The study synthesized ecotoxicological data from 13 critical effect concentrations, representing diverse biota responses to fuels at various degradation stages and carbon contents. This groundbreaking work provides a framework for managing fuel contamination in sub-Antarctic and Antarctic regions, informing remediation efforts and broader environmental protection strategies.
Seabird Populations and Ecosystem Recovery on Macquarie Island: A Palaeoecological Perspective
Macquarie Island's seabird populations exhibit significant recovery following the eradication of invasive species, as revealed by a palaeoecological study combining peat core analysis and contemporary monitoring. Radiometric dating and geochemical analyses of marine-derived nutrients from guano deposition demonstrated that seabird presence fluctuated dramatically over time, with notable declines during periods of invasive species dominance. The study underscores the effectiveness of invasive species eradication in restoring seabird populations and highlights the importance of integrating palaeoecological data with ongoing monitoring to assess ecosystem recovery. These findings provide critical insights for conservation management in subantarctic environments.
Anthropogenic petroleum signatures and biodegradation in subantarctic Macquarie Island soils
A study on Macquarie Island reveals complex petroleum contamination patterns, with evidence of multiple spills and variable biodegradation rates. Soil samples from contaminated sites, including a fuel farm and powerhouse, showed higher concentrations and diversity of hydrocarbons, indicative of repeated SAB diesel spills. However, some locations exhibited signatures suggestive of heavier fuels or crude oil, hinting at diverse contamination sources. Reference sites, though less contaminated, also displayed signs of fuel oil presence. The findings highlight the environmental impact of anthropogenic petroleum in subantarctic soils and underscore the need for robust monitoring and remediation strategies.
Assessing the cloud radiative bias at Macquarie Island in the ACCESS-AM2 model
A significant overestimation of downwelling surface shortwave radiation (+9.5±33.5 W m −2) and underestimation of longwave radiation (-2.3±13.5 W m −2) in the ACCESS-AM2 climate model was identified at Macquarie Island, with biases more pronounced during summer (+25.0±48.0 W m −2). The study utilized surface-based observations and lidar simulations to reveal that these radiation biases are linked to underestimated cloud fraction and low-level cloud occurrence, suggesting modeled cloud phase may also play a role. Additionally, the CERES product showed similar biases, indicating both require further development to improve accuracy in simulating Southern Ocean radiation. This long-term, seasonal evaluation highlights critical gaps in climate modeling that impact sea surface temperature and atmospheric circulation.
Earth-system-model evaluation of cloud and precipitation occurrence for supercooled and warm clouds over the Southern Ocean's Macquarie Island
A year-long study at Macquarie Island, part of the UNESCO-listed Southern Ocean, reveals that liquid-phase clouds precipitate approximately 70% of the time, with deeper and colder clouds showing higher precipitation frequency and intensity. Supercooled cloud layers also precipitate more readily than warmer ones, regardless of thickness. The research utilized ground-based profiling instruments during the Macquarie Island Cloud and Radiation Experiment (MICRE) to evaluate a 9-year Earth-system-model simulation using the GISS-ModelE3. The model, processed through the Earth Model Column Collaboratory (EMC 2), showed deficiencies in cloud occurrence and precipitation frequency but accurately reproduced observed tendencies for deeper clouds to precipitate more frequently. This study demonstrates a valuable framework for evaluating cloud radiative feedbacks in Earth-system models.
Slow recovery of stream invertebrates on subantarctic Macquarie Island after eradication of introduced rabbits and regrowth of vegetation
Stream invertebrate communities on subantarctic Macquarie Island showed slow recovery following the eradication of invasive rabbits and subsequent vegetation regrowth, with taxon richness and composition remaining largely unchanged a decade after rabbit removal. Initial sampling in 1992 recorded an average of 11.6 taxa per site, but this declined to 7.4–8.4 taxa during peak rabbit grazing (2000–2011). Despite substantial vegetation recovery by 2016, resampling revealed minimal improvement in invertebrate diversity and structure, suggesting limited refuges hindered rebound. The study, which resampled 13 of the original 15 sites using kick sampling, found that climate and water quality changes did not significantly influence recovery. These findings imply that stream ecosystems may require decades to recover from severe anthropogenic disturbances.
Southern Ocean Low Cloud and Precipitation Phase Observed During the Macquarie Island Cloud and Radiation Experiment (MICRE)
A significant portion of low clouds over Macquarie Island, particularly those with cold tops (≤0°C), exhibit predominantly liquid-phase characteristics at cloud base, despite the potential for mixed or ice-phase precipitation below. This study, conducted during the Macquarie Island Cloud and Radiation Experiment (MICRE) from April 2016 to March 2017, found that around two-thirds of low clouds were cold-topped, with these clouds being thicker and having higher bases compared to warm-topped clouds. The research utilized ground-based ceilometer, depolarization lidar, and W-band radar measurements to characterize cloud macrophysics and precipitation phase. Notably, 83–88% of cold-topped clouds were liquid at the base, while small-particle (low-radar-reflectivity) precipitation was mostly liquid below-cloud, contrasting with large-particle precipitation that was predominantly mixed or ice-phase. This insight is crucial for understanding the radiative properties and climate impacts of Southern Ocean low clouds.
Terrace types and vegetation dynamics on Macquarie Island
Macquarie Island's terraced landscapes reveal dynamic interactions between vegetation and terrain under current climatic conditions. A study of 38 non-windward terraced sites demonstrated that wind, moisture, slope stability, and vegetation collectively shape terrace forms, indicating an active process rather than a static one. This challenges the assumption that such features are relics of past environmental conditions, suggesting instead that they evolve in response to ongoing ecological and geological factors.
The unique marine ecosystem surrounding Macquarie Island
Macquarie Island's marine ecosystem, spanning approximately 478,000 km² within Australia’s Exclusive Economic Zone (EEZ), is a thriving biodiversity hotspot despite its harsh Sub-Antarctic environment. This study highlights the unique properties of the waters surrounding the island, emphasizing its role as one of the world's recovering wild places. The research underscores the significance of Macquarie Island's geoheritage and undersea features, which support a multitude of marine life. While Australia holds sovereign rights over this area, it also carries the responsibility to conserve and manage it for humanity. The study contributes to understanding the ecological dynamics and resilience of this unique marine ecosystem.
Tracking the origins of the introduced terrestrial amphipod, Puhuruhuru patersoni , on sub‐Antarctic Macquarie Island
A genetic analysis of the introduced amphipod Puhuruhuru patersoni on Macquarie Island reveals that the species likely originated from the southern region of New Zealand's South Island. The study, which compared mitochondrial DNA (mtDNA) data across the known range of P. patersoni, found significantly lower genetic diversity on Macquarie Island than in its native range. Phylogenetic reconstructions further supported this conclusion, suggesting that the introduction to the sub-Antarctic island was probably linked to historical activities between New Zealand and Macquarie Island. This finding sheds light on the origins of invasive species and their potential impact on fragile ecosystems like those found at UNESCO World Heritage Sites.
Ecology and management of invasive plants in the sub-Antarctic and Antarctic regions: evidence and synthesis from Macquarie Island
Invasive plant species, particularly those adapted to extreme cold conditions, pose significant threats to sub-Antarctic and Antarctic ecosystems. Research on Macquarie Island reveals that these species, such as Poa annua and Stellaria media, persist through large, long-lived soil seed banks and are facilitated by human introductions, animal disturbances, and climate change. While no single biological trait predicts invasiveness in the sub-Antarctic, ecological drivers like accidental human movement and soil disturbance enable their spread. The study emphasizes the need for proactive measures to prevent further invasion, develop low-impact control methods, and protect these fragile ecosystems from potential threats extending into Antarctica due to warming climates.
Hydrochemical and isotopic baselines for understanding hydrological processes across Macquarie Island
A comprehensive island-wide survey of Macquarie Island reveals that groundwater significantly influences lake hydrochemistry and hydrology, a factor previously overlooked. This study used stable isotope ratios (δ13C, δ18O, δ2H) and strontium isotopic ratios (87Sr/86Sr) to analyze 40 lakes, identifying distinct geochemical drivers such as sea spray aerosols on the western side and water–rock interactions in lower elevation catchments. Lakes at higher elevations were found to be more dilute, while those at lower elevations contained terrestrial-sourced ions, likely from groundwater. These findings provide critical baseline data for understanding nutrient cycling and ecosystem health, with implications for predicting shifts due to climate change.
So Close Yet So Far: Age and Growth of Blue Antimora Antimora rostrata (Moridae, Gadiformes, Teleostei) off New Zealand and Macquarie Island (Southwestern Pacific Ocean)
Blue antimora (Antimora rostrata) populations off Macquarie Island exhibit growth rates comparable to those in other Southern Ocean regions, including the Ross, Lazarev, and Weddell Seas, as well as near Kerguelen and Crozet Islands. However, individuals from New Zealand waters demonstrate significantly slower growth, akin to those found in the Flemish Cap area. This study analyzed age and growth patterns using samples collected from bycatch in the Patagonian toothfish longline fishery (Macquarie Island) and bottom trawl catches (New Zealand). Age estimates ranged from 11 to 44 years, with total lengths varying between 22.5–71.1 cm. The most abundant age classes differed between regions, suggesting potential stock structure variations. Further research is needed to clarify population distinctions across the species' broad range.
Southern Ocean Precipitation Characteristics Observed From CloudSat and Ground Instrumentation During the Macquarie Island Cloud & Radiation Experiment (MICRE): April 2016 to March 2017
A year-long study on Macquarie Island revealed that precipitation, primarily composed of small particles, occurred 44% of the time between April 2016 and March 2017. The research combined surface measurements from disdrometers, radars, and tipping buckets with CloudSat satellite data to analyze precipitation types and their characteristics. Key findings included the identification of distinct patterns in ice, mixed-phase, and rain precipitation, linked to the island's position relative to cyclonic low-pressure systems. Ice and mixed-phase precipitation were more common when Macquarie Island was northwest of these systems, while rain was frequent when southeast of them. Additionally, a weak diurnal cycle was observed, with higher frequencies between 03:00 and 06:00 local time. The study also noted that CloudSat overestimated total liquid precipitation and mixed-phase occurrences but accurately captured rain rates above 0.5 mm/hr.
The current trajectory of king penguin ( Aptenodytes patagonicus ) chick numbers on Macquarie Island in relation to environmental conditions
King penguin chick numbers on Macquarie Island have been declining at a rate of 1.06 ± 0.03% annually since 2007, marking the end of a rapid population increase observed from 1930 to 1980. Annual fluctuations in chick numbers, ranging from 33,513 to 78,714, were negatively correlated with environmental factors such as heavy rainfall, total rainfall, and maximum east coast wave height during incubation, as well as warmer sea surface temperatures in the penguins' foraging region. While causality remains uncertain due to interannual variability and the long generation time of king penguins, this study highlights a potential shift from population growth to stabilization or decline. Ongoing monitoring is crucial to determine the trajectory of this UNESCO-listed site's breeding population.
Rephotography, permanent plots and remote sensing data provide varying insights on vegetation change on subantarctic Macquarie Island, 1980–2015
A comprehensive analysis of vegetation change on Macquarie Island from 1980 to 2015 reveals that rephotography provides the most effective method for detecting spatial and temporal patterns of overall vegetation change, particularly in response to rabbit population dynamics. The study found stability in Acaena herbfield despite reduced disturbance, an increase in Pleurophyllum hookeri cover, and a rise in short grassland vegetation, while Azorella macquariensis cover remained constant. Although long-term plot data were less consistent with rephotography findings and more resource-intensive, sporadically available remote sensing data effectively monitored ground revegetation/devegetation but failed to detect other changes. The research highlights the importance of combining multiple monitoring approaches to accurately assess vegetation dynamics in subantarctic ecosystems.
Assemblages of myxomycetes on subantarctic Macquarie Island and tropical Christmas Island
A comparative study of myxomycete assemblages on subantarctic Macquarie Island and tropical Christmas Island reveals stark differences despite their similar sizes. Only nine species are shared between the two locations, highlighting distinct biogeographical patterns driven by extreme environmental contrasts. Surveys conducted in 1995 (Macquarie) and 2017 (Christmas) identified 85 species in total, including three new to science—two from Macquarie Island and one from Christmas Island. The research underscores the unique ecological niches occupied by myxomycetes in these isolated environments, with subantarctic conditions fostering a far less diverse but equally significant assemblage compared to tropical counterparts.
Evaluation of CERES and CloudSat Surface Radiative Fluxes Over Macquarie Island, the Southern Ocean
A recent evaluation of satellite-derived radiative fluxes over Macquarie Island, a UNESCO World Heritage Site in the Southern Ocean, reveals significant biases in global climate models. The study found that the Clouds and Earth's Radiant Energy System (CERES) and CloudSat retrievals underestimated shortwave radiation reflected back to space while overestimating surface-reaching longwave radiation, with annual mean biases of +10 W/m² for shortwave and -10 W/m² for longwave. These discrepancies, particularly pronounced at night due to poor cloud base representation, suggest that climate models may underestimate the Southern Ocean's radiative effects more than previously thought. The findings, based on surface observations from the Macquarie Island Cloud and Radiation Experiment (MICRE), highlight critical gaps in satellite data validation over this remote region.
Evidence of a Diurnal Cycle in Precipitation over the Southern Ocean as Observed at Macquarie Island
A diurnal cycle in precipitation over the Southern Ocean has been identified, with maximum rainfall occurring during night and early morning, and minimum in the afternoon. This pattern, observed at Macquarie Island from 1998 to 2016, is most pronounced in summer and suggests a significant contribution of marine boundary layer clouds to total precipitation. The study analyzed surface hourly precipitation data and twice-daily upper air soundings (1995–2011), revealing stronger lower tropospheric inversions at night, consistent with the observed diurnal cycle. These findings challenge the assumption that ERA-Interim precipitation products accurately represent natural variability, as they are dominated by a 12-hourly cycle likely due to twice-daily initialization. The implications for satellite-derived precipitation products, such as those from the A-Train constellation, are also discussed.
Macquarie Island Cloud and Radiation Experiment (MICRE) Field Campaign Report
A collaborative field campaign on Macquarie Island revealed critical insights into the behavior of clouds and radiation over the Southern Ocean. The Macquarie Island Cloud and Radiation Experiment (MICRE), conducted from March 2016 to March 2018, deployed advanced ground instrumentation to collect comprehensive data on surface radiation, cloud properties, precipitation, and aerosols. This study, led by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) user facility in partnership with the Australian Antarctic Division (AAD) and the Australian Bureau of Meteorology (BOM), aimed to deepen our understanding of these atmospheric phenomena. The campaign highlighted key data quality issues and developed value-added products to facilitate scientific analysis, providing a robust dataset for future research on climate dynamics in this pristine and ecologically significant region.
Southern Ocean sentinels: demographic insights into the declining population of Southern elephant seals at Macquarie Island
A long-term decline in the Southern elephant seal population at Macquarie Island, unique among stable or growing populations globally, is driven by extreme reproductive costs that significantly reduce survival rates for both first-time and experienced breeders. This study, using an 18-year capture-recapture dataset of over 6,000 individually marked females, revealed that environmental conditions during the post-moult foraging trip—critical to pregnancy initiation—play a pivotal role in whether seals skip reproduction. Incorporating this finding into matrix population models confirmed and re-evaluated the population's decline, offering potential clues to its causes. The research highlights how evolutionary and ecological processes shape life histories in long-lived species, contributing to broader understanding of predator dynamics in the Southern Ocean.
Using an expert judgment response matrix to assess the risk of groundwater discharges from remediated fuel spill sites to the marine environment at sub-Antarctic Macquarie Island, Australia
Residual contamination from remediated fuel spill sites at Macquarie Island poses minimal risk to adjacent marine communities, according to a comprehensive toxicity assessment. The study, using an expert judgment response matrix, found that even under worst-case exposure conditions—undiluted and continuous—native marine invertebrates showed variable and slow responses, with some species exhibiting no adverse effects. Natural site dynamics, such as rapid dilution due to high rainfall and energetic receiving environments, further mitigate potential risks. While toxicity was observed in certain species over extended periods (up to 21 days), no consistent patterns linked to hydrocarbon concentrations were identified. This research provides robust evidence that residual groundwater contamination at remediated sites is unlikely to harm marine ecosystems, offering critical insights for environmental risk assessment in sub-Antarctic regions.
Vegetation change on subantarctic Macquarie Island
Macquarie Island has undergone rapid vegetation change following the successful eradication of feral rabbits, rats, and mice in 2011. This large-scale project revealed that the absence of grazing pressure allows plant species distribution and vegetation structure to be primarily influenced by abiotic factors like climate. Research using repeat photographs over 34 years and satellite imagery demonstrated geographic variation in vegetation trends post-eradication. Spatial analysis showed that south-westerly winds were more damaging to plants than prevailing westerlies, while steep air temperature lapse rates limited diurnal and seasonal variation. Tussock grass and megaherbs, which declined by 2009, rebounded by 2014 without grazing pressure. However, high-elevation feldmark vegetation showed no consistent trends linked to rabbit impacts or climate change. Species distribution models indicated that generalist plant species have a smaller 'core range' where they dominate. The study highlights the ongoing ecosystem recovery and the interplay between climate change and the absence of grazing in shaping Macquarie Island's lowland vegetation.
Warmer and less variable temperatures favour an accelerated plant phenology of two invasive weeds across sub‐Antarctic Macquarie Island
Climate change is enhancing the invasive capabilities of two weed species, Poa annua and Cerastium fontanum, on sub-Antarctic Macquarie Island. The study found that warmer, less variable temperatures accelerate plant growth and phenological development in P. annua, while temperature variability negatively impacts both species. Despite their distinct reproductive strategies, both species successfully produce seeds across all studied sites, demonstrating remarkable acclimation to extreme conditions. This suggests that climatic warming could significantly boost the invasiveness of alien plants even in remote sub-polar regions, underscoring the urgent need for proactive management to prevent further spread.
Assessing the efficacy and impact of management of an invasive species in a protected area: Poa annua on sub‐Antarctic Macquarie Island
Management of invasive species in remote, protected areas poses significant challenges due to the difficulty of eradication and potential off-target impacts. This study assessed the efficacy and impact of both physical and chemical control methods on Poa annua, an invasive grass species, at sub-Antarctic Macquarie Island. While none of the four physical disturbance methods tested effectively reduced P. annua cover as one-off treatments, herbicides such as glyphosate and trifloxysulfuron sodium proved effective with minimal damage to native grasses, indicating potential selectivity. The research highlights that an integrated weed management program, combining strategic herbicide use with follow-up chemical and physical interventions, could balance control outcomes and biodiversity preservation. This study underscores the importance of site-specific testing of control methods and understanding their off-target impacts in managing alien plant species in protected areas.
Mitogenomes Uncover Extinct Penguin Taxa and Reveal Island Formation as a Key Driver of Speciation
A groundbreaking analysis of penguin mitogenomes reveals that island formation has been a pivotal driver of penguin speciation, with multiple recently extinct taxa emerging on geologically young islands. The study identifies two new extinct penguin species from New Zealand's Chatham Islands: Eudyptes warhami and a dwarf subspecies of the yellow-eyed penguin (Megadyptes antipodes richdalei), which diverged shortly after the islands' emergence around 3 million years ago. Using fossil-calibrated phylogenies, researchers demonstrate that island-endemic penguins, including those from the Galápagos, Gough, Antipodes, Snares, and Macquarie Islands, underwent rapid diversification during the Plio-Pleistocene. This work underscores the profound impact of island formation on penguin evolution while highlighting the severe consequences of anthropogenic extinctions on isolated archipelagos.
Response of the Native Springtail Parisotoma insularis to Diesel Fuel–Contaminated Soils Under Field-Realistic Exposure Conditions at Subantarctic Macquarie Island
A critical effect concentration (CEC) of 48 mg/kg for diesel fuel was established for the native springtail species Parisotoma insularis, demonstrating its sensitivity to fuel contamination regardless of soil organic content. This is the first study to derive such data for a subantarctic springtail, providing essential insights for remediation efforts and soil quality guideline values on Macquarie Island and beyond. The research involved collecting intact soil cores along an organic carbon gradient, spiking them with diesel to mimic field conditions, and assessing springtail response. These findings are pivotal for risk assessment and environmental management in subantarctic regions affected by fuel spills.
The Macquarie Island (LoFlo2G) high-precision continuous atmospheric carbon dioxide record
A high-precision, continuous atmospheric carbon dioxide (CO₂) record from Macquarie Island (54°37′S, 158°52′E), spanning 2005–2016, reveals critical insights into the Southern Ocean's role as a global CO₂ sink. The study leveraged ultra-high-precision LoFlo2 measurements, achieving uncertainty estimates of 0.01–0.05 µmol mol⁻¹, to distinguish oceanic and atmospheric CO₂ fluxes in this remote region. By filtering local and hemispheric CO₂ sources using within-minute standard deviation metrics and model-simulated radon concentrations, the team produced a noise-free seasonal variation record, surpassing the accuracy of traditional flask measurements. This breakthrough enhances our understanding of the Southern Ocean's spatial and temporal CO₂ dynamics, particularly when integrated with data from other Southern Hemispheric sites.
Factors influencing the habitat use of sympatric albatrosses from Macquarie Island, Australia
Research on sympatric albatrosses from Macquarie Island reveals that black-browed albatrosses are more vulnerable to climate-driven changes due to their shorter breeding cycle and morphological traits, which limit flight efficiency. The study tracked 47 albatrosses—black-browed (Thalassarche melanophris), grey-headed (T. chrysostoma), light-mantled (Phoebetria palpebrata), and wandering (Diomedea exulans)—over 1994–2009, finding that habitat overlap was greatest near the island during breeding but varied widely in nonbreeding periods. All species utilized productive frontal regions and mesoscale eddies, with optimal residence times linked to moderate wind speeds, enhancing aerodynamic performance. These findings highlight potential risks for black-browed albatrosses as climate shifts alter Southern Ocean wind patterns and Subantarctic Front dynamics.
Managing invasive plants on sub-Antarctic Macquarie Island
Macquarie Island faces significant threats from invasive plant species introduced through human activity. Only three species—Poa annua, Stellaria media, and Cerastium fontanum—are well-established, with strict biosecurity measures in place to prevent further introductions. Research indicates that these weeds, though palatable, may have been suppressed by rabbit grazing. Post-rabbit eradication, weed proliferation could disrupt the island's ecosystem structure and function, necessitating targeted control strategies. The study proposes integrating both non-native plant and herbivore management for effective restoration. While S. media shows promise for easier management or potential eradication due to its limited distribution, knowledge gaps remain regarding soil seed banks, population dynamics post-eradication, and herbicide impacts in cold conditions. Ongoing research addresses these gaps, including studies on herbicide movement and fate in Macquarie Island's unique environment, despite logistical challenges.
Analysis of Ionospheric Scintillation Characteristics in Sub-Antarctica Region with GNSS Data at Macquarie Island
Ionospheric scintillation, which significantly impacts radio propagation and electronic systems, exhibits distinct temporal and spatial patterns influenced by solar and geomagnetic activities. A study analyzing GNSS data from Macquarie Island (2011–2015) reveals that amplitude scintillation closely correlates with solar activity, while phase scintillation is more strongly linked to geomagnetic disturbances. Additionally, the research identifies statistical relationships between scintillation behavior and satellite elevation/azimuth angles. These findings enhance the understanding of ionospheric dynamics in sub-Antarctic regions, providing critical insights for GNSS applications and mitigating potential disruptions in navigation systems.
Land-based observations of cetaceans and a review of recent strandings at subantarctic Macquarie Island
A comprehensive study reveals that most cetacean species are relatively uncommon in the inshore waters of Macquarie Island. Over 391 systematic one-hour observation periods spanning 59 weeks in 2002 and 2003, nine species were identified, with killer whales, long-finned pilot whales, and sperm whales detected with some frequency. The remaining species were observed only once, indicating limited presence near the island. Additionally, eight previously unpublished stranding records are summarized, contributing to the understanding of marine megafauna in the region. The study underscores the importance of routine archiving of cetacean sightings from shipping activities to enhance knowledge of this subantarctic ecosystem.
Rabbit haemorrhagic disease: Macquarie Island rabbit eradication adds to knowledge on both pest control and epidemiology
A successful rabbit eradication campaign on sub-Antarctic Macquarie Island, using the Rabbit haemorrhagic disease virus (RHDV), challenged the prevailing notion that cool or humid climates limit RHDV efficacy. The study found that heavy rabbit mortality occurred despite these conditions, suggesting that a non-pathogenic calicivirus (RCV-A1) present in other regions may instead inhibit RHDV spread and reduce disease severity. This discovery advanced understanding of both pest control dynamics and the epidemiology of RHDV, demonstrating its potential as an effective tool even in challenging environments. The research also highlighted how RHDV complemented traditional eradication methods, such as aerial baiting, by reducing secondary poisoning risks to seabirds.
Change in the distribution of the indigenous grass Poa litorosa on sub-Antarctic Macquarie Island following the eradication of rabbits
A dramatic expansion of the indigenous grass Poa litorosa on sub-Antarctic Macquarie Island has been observed following the eradication of rabbits, rats, and mice. Previously confined to just four restricted populations, this species has now spread significantly across the island due to the release from grazing pressure. Long-term monitoring over 24 years revealed that rabbit grazing had suppressed P. litorosa growth in unfenced areas, while fenced plots showed thriving populations during peak rabbit numbers. The study highlights the unforeseen ecological impacts of invasive species eradication and underscores the importance of continued monitoring to track such changes on this UNESCO-listed site.
Hydrothermal contributions to global biogeochemical cycles: Insights from the Macquarie Island ophiolite
Hydrothermal alteration of the Macquarie Island ophiolite reveals significant chemical exchanges between ocean crust and seawater, with net fluxes indicating that elements like Si, Ti, Al, and Ca are transferred to the oceans, while H₂O, Mg, Na, K, and S are sequestered in the crust. This study leverages the unique sub-aerial exposure of a complete oceanic crust section to quantify these processes, demonstrating that elemental uptake by veins plays a crucial role for elements like Si, Fe, Mg, and S. The findings suggest that hydrothermal activity could balance riverine inputs of Mg to the oceans, though relationships between spreading rates and chemical exchange fluxes remain poorly understood.
Understanding Orographic Effects on Surface Observations at Macquarie Island
Research on Macquarie Island reveals that the island's modest elevation (410 m) has limited orographic effects on precipitation, except for enhancing drizzle during southwesterly winds. Using high-resolution numerical simulations with and without terrain, the study analyzed four common synoptic patterns: cold fronts, warm fronts, postfrontal drizzle, and midlatitude cyclones. The findings indicate that while the island can perturb clouds and precipitation, its shallow height (nondimensional mountain height < 1 in 93.5% of cases) often allows boundary layer flow to pass over it, with greater impact observed in the lee. The weather station's location on the island's north end further limits significant orographic effects, except during specific wind conditions.
A Climatology of the Precipitation over the Southern Ocean as Observed at Macquarie Island
Macquarie Island, a remote subantarctic site with modest elevation, provides critical insights into Southern Ocean precipitation patterns. A 32-year analysis (1979–2011) reveals that the ERA-Interim reanalysis underestimates annual precipitation by 6.8% compared to ground observations, highlighting significant biases in climate models over this region. Light precipitation dominates (29.7%), while heavy rainfall (≥1.5 mm/h) is rare but often linked to fronts and cyclonic systems, though some events occur without clear meteorological triggers. The study also identifies discrepancies between satellite-derived drizzle data and ground observations, suggesting limitations in reanalysis products for detecting weak precipitation. Two case studies further explore these inconsistencies, emphasizing the need for improved climate modeling in the Southern Ocean.
New Additions to the Liverwort Flora of Subantarctic Macquarie Island
A recent study has significantly expanded the known liverwort flora of Macquarie Island, a UNESCO World Heritage Site in the Subantarctic. Researchers identified 16 new species, including two non-type varieties, bringing the total number of recorded liverworts on the island to 62. This makes Macquarie Island's hepatic diversity second only to South Georgia in the Subantarctic region. The study also introduced a new combination for Lophocolea novaezeelandiae var. meridionalis. The findings were derived from detailed taxonomic analysis, contributing valuable insights into the biodiversity of this remote and ecologically significant site.
Antarctic Circumpolar Current transport and barotropic transition at Macquarie Ridge
A deep, high-speed jet within the Antarctic Circumpolar Current (ACC) transports substantial water volumes through a 50 km-wide gap north of Macquarie Island, revealing critical insights into how the ACC navigates large topographic obstacles. The study, combining direct velocity measurements, satellite altimetry, and ocean state estimates, demonstrates that the Subantarctic Front crosses the Macquarie Ridge through this gap, where the ACC becomes more barotropic. The deep jet's acceleration is balanced by ageostrophic pressure gradients, zonal momentum convergence, and dissipation, highlighting the role of local nonlinear processes in the dynamical balance of the ACC. This research provides observational evidence to support theoretical predictions about topographic interactions shaping the ACC's dynamics.
The aerial invertebrate fauna of subantarctic Macquarie Island
A comprehensive study of Macquarie Island reveals that passive aerial dispersal is significantly more prevalent among its invertebrate fauna than previously understood. Over 3000 invertebrates from seven insect orders and other arthropods were collected using wind-traps between 1991 and 1994, with over half of the catch consisting of flightless species. This indicates widespread short-distance dispersal across the island, challenging earlier assumptions about movement patterns. While long-distance dispersal events were rare, the study suggests that aerial pathways could occasionally facilitate the arrival of exotic species, though other explanations for their presence are equally plausible.
Vegetation-Banked Terraces on Subantarctic Macquarie Island: A Reappraisal
A reappraisal of vegetation-banked terraces on Macquarie Island reveals that previously described 'windward' and 'leeward' types are not distinct but instead represent a continuum influenced by hillside aspect. The study documents dynamic processes, including mobile gravel, substrate erosion, and vegetation growth, challenging the notion of separate terrace forms. Additionally, stone-banked terraces, not previously reported on the island, were identified. Recent die-offs of the cushion plant Azorella macquariensis may threaten long-term terrace stability. The research combines morphological documentation with process-based analysis to provide new insights into these unique subantarctic landscapes.
Ecological Restoration of Sub-Antarctic Macquarie Island
A significant reduction in invasive species on Macquarie Island has been achieved through targeted eradication efforts. The study, funded with AUD$24.7M, successfully eliminated ship rats and house mice post-baiting, while the European rabbit population dropped from an estimated 150,000 to fewer than 30. Rabbit Haemorrhagic Disease Virus (RHDV) was introduced in 2011 to minimize non-target seabird mortality during aerial baiting. The project employed both aerial baiting and ground hunting, with ongoing monitoring expected for at least two years post-baiting. Early signs of vegetation recovery and increased burrownesting seabird activity were observed within six months, indicating the ecological restoration's positive impact on the island's flora and fauna.
King penguin population on Macquarie Island recovers ancient DNA diversity after heavy exploitation in historic times
King penguin populations on Macquarie Island have recovered ancient genetic diversity within just 80 years, despite near-extinction due to historical human exploitation. This remarkable resilience is attributed to conservation efforts that enabled the population to expand and recolonize both previous and new sites. Researchers used ancient DNA methods to compare past and modern genetic diversity, revealing that current populations on northern Macquarie Island mirror historical levels of variation. The study highlights the effectiveness of conservation in restoring not only population numbers but also genetic diversity, offering a promising model for species recovery.
Methods for mapping the tundra vegetation of sub-Antarctic Macquarie Island
A novel mapping technique for sub-Antarctic tundra vegetation, particularly the critically-endangered cushion plant Azorella macquariensis, has been developed and validated with high accuracy. This approach combines very high-resolution satellite imagery, terrain modeling, and random forest classification to overcome challenges posed by Macquarie Island's remote location, cloud cover, and small-statured vegetation. The study demonstrates that traditional community-based mapping is ineffective due to the island's ecological disturbance, necessitating single-species mapping. Additionally, a new photographic field sampling method reduces field time while maintaining data quality compared to conventional quadrat methods. Geographically-stratified random sampling effectively captures terrain-driven plant distribution variations, providing a robust framework for monitoring rapid vegetation changes on this UNESCO World Heritage Site.
Non-Target Species Management for the Macquarie Island Pest Eradication Project
The Macquarie Island Pest Eradication Project (MIPEP) successfully mitigated non-target species impacts while progressing toward eradicating invasive rodents and European rabbits. Initial baiting in 2010, delayed by adverse weather, resulted in non-target mortality across six seabird and duck species, prompting a review that confirmed long-term ecosystem benefits despite short-term risks. Enhanced mitigation strategies—including the release of Rabbit Haemorrhagic Disease Virus to reduce rabbit populations and increased carcass removal efforts—were implemented before resuming baiting in 2011. Monitoring during subsequent operations revealed no significant population-level impacts on seabirds, with only minor transitory effects observed in king penguin colonies and no adverse effects on wandering albatross chicks or marine mammals. The project demonstrates that targeted pest eradication can be achieved with minimal lasting harm to non-target species when adaptive mitigation measures are applied.
Plateau vegetation on sub-Antarctic Macquarie Island
A 1980 line transect survey on Macquarie Island's plateau revealed that its open herb vegetation, shaped by strong westerly winds, comprised 62 species with occurrences ranging from 16.7% to 99.5%. The cushion plant Azorella macquariensis was a dominant component, appearing at 14 of 16 sites and reaching up to 50% coverage. This pre-dieback data provides a critical baseline for assessing future changes in the island's plateau vegetation, which has since experienced severe dieback of A. macquariensis.
Evidence for long‐distance dispersal of Sophora microphylla to sub‐Antarctic Macquarie Island
A single seed of kowhai (Sophora microphylla), a species not native to Macquarie Island, was discovered on the island's lakeshore. This finding suggests that long-distance dispersal by birds, followed by additional transport mechanisms, may enable the colonization of oceanic islands by certain plant species, including those in the Edwardsia group of Sophora. The discovery highlights the potential for multi-stage dispersal processes to overcome geographical barriers in sub-Antarctic ecosystems.
Interaction of Gravity Flows With a Rugged Mid-Ocean-Ridge Seafloor: An Outcrop Example from Macquarie Island
Rugged bathymetry along slow-spreading mid-ocean ridges significantly influences gravity flows derived from oceanic fault scarps, as demonstrated by sedimentary lithofacies variations on Macquarie Island. The study reveals that pillow-basalt terranes funnel gravity flows into confined bedrock corridors, leading to systematic vertical and lateral changes in sediment deposition. Initial stages of corridor filling suppress flow dilution due to tight confinement, while later stages promote more dilute flows with lateral gradations from coarse-grained axial turbidites to thinly interbedded overbank facies. Partly confined tabular-basalt-floored basins show lateral expansion and dilution of gravity flows, recording multiple reflections off fault barriers and preserving coarsening-upward trends indicative of sediment-starved submarine fans.
Island tourism: sustainable perspectives
Island tourism, particularly on UNESCO World Heritage Sites like Macquarie Island, faces significant ecological, social, and economic challenges that require sustainable solutions. The study highlights the delicate balance between conservation efforts and tourism development, emphasizing the need for ecologically sustainable practices to mitigate environmental impacts such as invasive species (e.g., rabbits and rats) and sand mining. Social sustainability is also critical, with a focus on maintaining positive host-guest interactions while addressing cultural sensitivities and potential conflicts, such as those seen in Trinidad and Tobago or casino-driven tourism in St. Croix. Economically, the research underscores the importance of adaptive strategies to rejuvenate tourism markets, as demonstrated by cases from Mauritius and Okinawa, ensuring long-term viability without compromising ecological integrity or social cohesion. The study employs comparative analyses across diverse island settings to derive actionable insights for policymakers and stakeholders.
Lanternfish (Pisces: Myctophidae) biomass distribution and oceanographic–topographic associations at Macquarie Island, Southern Ocean
Lanternfish biomass at Macquarie Island is significantly enhanced where the Subantarctic Front (SAF) interacts with the Ridge Gap, a topographic break in the Macquarie Ridge. This study documents for the first time the summertime lanternfish assemblage, dominated by Krefftichthys anderssoni and Gymnoscopelus braueri, revealing mean biomass of 3.13 g per 1000 m³ in the Ridge Gap—nearly five times higher than over the Abyssal Plain (0.71 g) and double that on the Macquarie Ridge (1.26 g). The research suggests that oceanographic-topographic interactions, such as eddy systems and productivity fronts, play a crucial role in attracting lanternfish to this region. These findings highlight the vulnerability of this ecosystem to climate-mediated changes, with potential cascading effects on commercially and conservationally significant predators.
Rapid commencement of ecosystem recovery following aerial baiting on sub-Antarctic Macquarie Island
Aerial baiting for invasive rabbits on sub-Antarctic Macquarie Island triggered rapid recovery of the native tussock grass Poa foliosa, a key component of the island’s ecosystem. Within six months of initiating the eradication program in winter 2010, substantial regrowth was observed, demonstrating the potential for swift ecological restoration following localized removal of invasive herbivores. This finding provides critical insights into monitoring and evaluating the success of vertebrate pest control efforts on fragile island ecosystems.
Response of stream invertebrate communities to vegetation damage from overgrazing by exotic rabbits on subantarctic Macquarie Island
A significant decline in stream invertebrate taxa and abundance on Macquarie Island, attributed to vegetation damage from overgrazing by exotic rabbits, was documented between 1992 and 2010. Taxa richness dropped by 25–36%, and ordination analysis revealed marked compositional shifts, particularly at sites with moderate or severe grazing impacts. The study suggests that altered organic material input into streams, due to vegetation damage, may have driven these changes. If such degradation persists without refuges, stream invertebrate communities could undergo permanent alteration, posing risks to the island's delicate ecosystem.
Three new remarkable carnivorous sponges (Porifera, Cladorhizidae) from deep New Zealand and Australian (Macquarie Island) waters
Researchers have discovered three new species of carnivorous sponges (Cladorhizidae) in deep waters around New Zealand and Macquarie Island, each exhibiting remarkable deviations from known sponge morphology. Abyssocladia carcharias stands out with its pedunculate disc shape and unique multidentate isochelae, while Asbestopluma (Asbestopluma) anisoplacochela introduces a novel microsclere form, the anisoplacochelae, characterized by dissimilar plate-like central teeth. Asbestopluma (Asbestopluma) desmophora features densely packed desma megascleres at its base and exhibits dichotomous branching. These findings challenge existing phylogenetic understandings of Cladorhizidae and highlight the biodiversity of deep-sea environments in the region, including Macquarie Ridge.
A detrital record of lower oceanic crust exhumation within a Miocene slow-spreading ridge: Macquarie Island, Southern Ocean
Macquarie Island's sedimentary record reveals the exhumation of lower oceanic crust from a Miocene slow-spreading ridge, providing insights into tectonic processes in the Southern Ocean. The study identifies two distinct lithofacies: basal basaltic breccia and enriched mid-ocean-ridge basalt (E-MORB) with gabbroic intercalations. Basaltic detritus reflects upper oceanic crust metamorphism, while gabbroic detritus indicates deeper crustal sources. Geochemical analysis and zircon geochronology suggest the gabbroic material originated from Paleogene-aged tholeiitic MORB, likely sourced from the Southeast Indian Ridge via a long-offset transform fault. This research reconstructs the tectonic history of Macquarie Island, highlighting the role of transpression in shaping its geological features.
Qualitative modelling of invasive species eradication on subantarctic Macquarie Island
Simultaneous eradication of rabbits, rats, and mice from Macquarie Island is strongly supported by qualitative modelling due to the high likelihood of continued ecological impacts if only one or two species are targeted. The study predicts positive outcomes for native tall tussock vegetation and burrow- and surface-nesting seabirds but also highlights risks, such as potential failure in eradicating mice and unintended consequences from redpolls and starlings. This approach demonstrates that qualitative modelling can provide consistent insights even with significant ecosystem uncertainty, aiding strategic conservation planning.
Twentieth century constraints on sea level change and earthquake deformation at Macquarie Island
A rare combination of historical sea level observations from Sir Douglas Mawson's 1911–1914 Australasian Antarctic Expedition and modern data reveals a surprising land subsidence rate at Macquarie Island, contradicting geological evidence of long-term uplift. The study estimates relative sea level rise at +4.8 ± 0.6 mm/yr, suggesting the island is sinking despite geological uplift over millennia. Analysis of GPS data from 2000–2009 refines the source parameters of a 2004 Mw∼8.0 earthquake and infers an asthenospheric viscosity of 3×10^19 Pa s, providing insights into the island's tectonic evolution. The findings also indicate that ongoing viscoelastic relaxation from a 1924 earthquake contributes significantly to vertical deformation, with absolute sea level change estimated at +2.0 ± 0.8 mm/yr over the twentieth century, aligning with global averages.
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