Publications
Significant impact of lithogenic dissolution from subantarctic volcanic islands on the regional marine silicon cycle
A significant contribution of lithogenic silicon (Si) from subantarctic volcanic islands, specifically Heard and McDonald Islands, has been identified as a major source of dissolved Si in the regional marine environment. This study reveals that the dissolution flux of lithogenic Si around these islands is among the highest globally, with an estimated specific flux of 3.7 ± 2.3 × 10^6 mol km^-2 yr^-1. The findings suggest that active volcanic activity and subglacial erosion on Heard Island are likely responsible for this high dissolution rate. The research utilized Si isotopic signatures to differentiate between dissolved and biogenic Si, demonstrating that lithogenic Si dissolution significantly impacts the regional marine silicon cycle and has traceable biogeochemical effects over the Northern Kerguelen Plateau.
McDonald Islands Phonolitic Lavas: Evidence for Zonation of the Kerguelen Plume
Research on the McDonald Islands reveals evidence of zonation within the Kerguelen mantle plume, a long-lived volcanic hotspot. The study identified a new magma series, the McDonald Series, characterized by distinct geochemical signatures (low εHf, Δ207Pb/204Pb, and Δ208Pb/204Pb) in fresh phonolitic lavas dredged from sea knolls around the islands. These lavas, dated to the Pleistocene-Holocene period (73.7 ± 15.1 ka to 7.0 ± 2.7 ka), suggest a younger, distinct volcanic phase linked to a specific component of the plume. The findings propose that this series, along with older lavas from the Ninetyeast Ridge, provides evidence for chemical and temporal zonation within the Kerguelen plume, challenging previous assumptions about its homogeneity.
Population dynamics and spatial structure of the grey rockcod (Lepidonotothen squamifrons) in the vicinity of Heard Island and the McDonald Islands
Research identifies three distinct metapopulations of grey rockcod (Lepidonotothen squamifrons) around Heard Island and the McDonald Islands, highlighting significant variations in biological parameters such as age, growth, maturity, sex ratio, body condition, and population density. This study, based on trawl survey data from 1990 to 2014, suggests that these separate metapopulations may explain the species' slow recovery after commercial extinction due to overfishing in the Southern Ocean. The findings underscore the importance of considering meta-population structure in management strategies for sustainable conservation and recovery efforts.
The conservation status of Heard Island and the McDonald Islands
Heard Island and the McDonald Islands, the last unspoilt subantarctic biome, face increasing threats from human activity despite their extreme isolation. This study reveals that current legal protections are insufficient to maintain their biological integrity, highlighting a delicate conservation balance. It identifies urgent reforms, including new legislation or integration under the Antarctic Treaty (Environmental Protection) Act 1980, as critical for their future preservation. The research combines historical, geographical, and biological analysis with an assessment of existing legal controls, advocating for stronger measures to safeguard these unique ecosystems. Recommendations include declaring the Islands a UNESCO Biosphere Reserve or World Heritage Site, contingent on implementing prior reforms.
The sub-Antarctic islands are increasingly warming in the 21st century
Sub-Antarctic islands, including Heard and McDonald Islands, are experiencing accelerated warming trends in the 21st century. This study confirms that air temperatures across these remote islands—located near the Antarctic Polar Front—have risen significantly, driven by anthropogenic influences such as the positive phase of the Southern Annular Mode (SAM) and intensified westerly winds. While mid-to-late 20th-century warming was previously documented, this research provides updated assessments of recent trends, suggesting continued warming through the century. The findings highlight potential disruptions to landscape and ecosystem processes, though specific impacts remain speculative at this stage.
Atmospheric inputs of volcanic iron around Heard and McDonald Islands, Southern ocean
Volcanic emissions from Heard Island on the Kerguelen plateau significantly increase atmospheric iron (Fe) loading and solubility, highlighting volcanoes as crucial sources of aeolian Fe for remote oceanic regions. This discovery challenges conventional models that often overlook volcanic contributions to marine ecosystems. The study analyzed atmospheric samples around Heard and McDonald Islands in the Southern Ocean, revealing elevated Fe concentrations linked to volcanic activity. These findings underscore the importance of incorporating volcanic inputs into biogeochemical models to better understand nutrient cycling in the remote Southern Ocean.
Hull fouling marine invasive species pose a very low, but plausible, risk of introduction to East Antarctica in climate change scenarios
A very low but plausible risk exists for hull fouling marine invasive species to establish in East Antarctica, including its subantarctic islands, under current and future climate change scenarios. A machine-learning model identified four species as potential immediate threats and five more as risks by the end of this century, with Asterias amurensis posing a threat across all locations studied. The research used gradient-boosted machine learning (XGBoost) to assess environmental suitability based on sea surface temperature, salinity, nitrate levels, and pH, revealing that while adult survival is possible, successful reproduction and establishment remain unlikely due to limited propagule pressure. These findings underscore the need for a precautionary approach, emphasizing surveillance and monitoring in this pristine region.
The distribution of four species of the genus Macrourus (Gadiformes: Macrouridae) from the Southern Ocean based on samples from the toothfish longline fishery
Research extends the known distribution of four species of the genus Macrourus in the Southern Ocean, with significant findings for Macrourus caml and Macrourus holotrachys. Macrourus caml's range is now documented to include the Ob and Lena Banks area and southwest of Heard and McDonald Islands, while Macrourus holotrachys has been recorded from Prince Edward Islands and the Ob and Lena Banks. Additionally, Macrourus whitsoni was confirmed in the southeast Atlantic Ocean near Maud Land, aligning with previous reports. The study utilized samples collected from the toothfish longline fishery to refine species distribution data and provide a revised identification key for these species.
Glacial and Hydrothermal Sources of Dissolved Iron (II) in Southern Ocean Waters Surrounding Heard and McDonald Islands
Heard and McDonald Islands (HIMI) serve as significant sources of dissolved iron (II) (DFe(II)) in the Southern Ocean, with distinct mechanisms governing its release. Heard Island's glacial runoff contributes reduced iron, while McDonald Islands' shallow hydrothermal activity is a notable source. The study, conducted during the austral summer of 2016, used DFe(II) and hydrogen peroxide measurements to identify these sources. Elevated DFe(II) concentrations around HIMI, reaching up to 1.01 nmol L⁻¹ near McDonald Islands, suggest increased iron availability for marine biota and potential transport to the broader Kerguelen Plateau, where annual plankton blooms occur.
Identifying Zinc Inputs to Heard and McDonald Islands Region using Zinc Concentrations and Isotopic Compositions
Research indicates that hydrothermal activity near Heard and McDonald Islands, an active volcanic region in the Southern Ocean, may be contributing zinc (Zn) to surrounding waters. This study used Zn concentrations and isotopic compositions to explore potential Zn sources, suggesting a possible hydrothermal influence near McDonald Island and specific stations around Heard Island. The findings hint at enhanced biological productivity due to trace element inputs from volcanic activity. To strengthen conclusions, additional data such as Zn excess and mantle helium concentrations are recommended.
Factors Controlling the Lack of Phytoplankton Biomass in Naturally Iron Fertilized Waters Near Heard and McDonald Islands in the Southern Ocean
Despite high natural iron fertilization from glacial and volcanic sources near Heard and McDonald Islands, phytoplankton biomass remains unexpectedly low compared to the central Kerguelen Plateau. This paradoxical 'high nutrient, high iron, low chlorophyll' (HNHFeLC) phenomenon was investigated using ocean color data and in situ samples collected during the HEOBI voyage in 2016. Researchers found that deep mixing, shading by re-suspended sediment particles, and dilution with surrounding low-chlorophyll waters in the Antarctic Circumpolar Current played significant roles in limiting phytoplankton growth. Additionally, a shift from microphytoplankton to nanophytoplankton dominance was observed, highlighting the complex dynamics of short-term responses to climate change and cryospheric processes.
Managing Marine Protected Areas in Remote Areas: The Case of the Subantarctic Heard and McDonald Islands
The Heard Island and McDonald Islands (HIMI) Marine Reserve, one of the world's most remote marine protected areas (MPAs), has successfully balanced sustainable fisheries with biodiversity conservation. Despite its harsh conditions and isolation, the reserve has seen no illegal fishing since 2006/07, thanks to collaboration between managers and the fishing industry. Commercial fishers actively monitor the area, report infringements, and conduct annual ecological surveys, providing critical data for environmental tracking. This partnership, underpinned by secure fishing rights, demonstrates that remote MPAs can achieve conservation outcomes when governance integrates industry participation and robust monitoring. The study highlights the potential for similar models in other remote large MPAs, offering a blueprint for cost-effective conservation strategies.
Shallow Seafloor Gas emissions Near Heard and McDonald Islands on the Kerguelen Plateau, Southern Indian Ocean
Researchers have uncovered evidence of submarine gas emissions near Heard and McDonald Islands on the Kerguelen Plateau, marking the first documented seafloor bubble production in this remote region. The study, utilizing hydroacoustic flares, deep-tow camera footage, water properties analysis, and isotopic data (δ³He, δ¹³C, δ³⁴S), identified potential sources of methane and CO₂ linked to both shallow diffuse hydrothermal venting near McDonald Islands and deeper-sourced thermogenic methane or sediment-hosted geothermal systems at Heard Island. The findings suggest active carbon cycling processes in the southern Indian Ocean, with implications for understanding seafloor dynamics and volcanic activity on large igneous provinces.
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