Ross Island Research Articles

Archaeological Excavation and Artefact Conservation at the Heroic-era Expedition Bases, Ross Island, Antarctica.

Four expedition bases built during the Heroic Era (1897- 1922) of polar exploration remain standing in the Ross Sea region in Antarctica. Conservation work and archaeological excavation carried out by the Antarctic Heritage Trust on two of these huts, Captain Robert Falcon Scott’s 1910 base at Cape Evans, and Sir Ernest Shackleton’s 1907 base at Cape Royds is the focus of this article. A combined estimate of 14000 artefacts are contained within these base buildings and in their immediate environs. The buildings and their contents provide unique connections and insights into life, expeditions and science in Antarctica 100 years ago. Many artefacts which lie outside the huts remain buried in permafrost or frozen in ice. These are often well preserved in this frozen state. However, artefacts can become exposed during periods of low snowfall, the summer melt period, and during any excavation work that forms part of the building conservation programme. Exposed artefacts can be subjected to increased UV, wind and wind-blown gravel erosion, freeze-thaw cycles, melt-water, wildlife and human visitor damage. This paper will describe the logistical challenges faced by working on conservation at these historic bases in Antarctica. Antarctic archaeological process and decision making by the Antarctic Heritage Trust will be discussed, as developed following earlier work by Dr Neville Ritchie. Strategies for mitigating future degradation will also be explored.

Characterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica

Dissolved humic material (HDOM) is ubiquitous to all natural waters and its source material influences its chemical structure, reactivity, and bioavailability. While terrestrially derived HDOM reference materials distributed by the International Humic Substances Society (IHSS) have been readily available to engineering and scientific communities, a microbially derived reference HDOM was not, despite the well-characterized differences in the chemistry and reactivity of HDOM derived from terrestrial versus microbial sources. To address this gap, we collected a microbial reference fulvic acid from Pony Lake (PLFA) for distribution through the IHSS. Pony Lake is a saline coastal pond on Ross Island, Antarctica, where the landscape is devoid of terrestrial plants. Sample collection occurred over a 17-day period in the summer season at Pony Lake. During this time, the dissolved organic carbon (DOC) concentrations increased nearly two-fold, and the fulvic acid fraction (collected using the XAD-8 method) accounted for 14.6% of the DOC. During the re-concentration and desalting procedures we isolated two other chemically distinct fulvic acid fractions: (1) PLFA-2, which was high in carbohydrates and (2) PLFA-CER, which was high in nitrogen. The chemical characteristics (elemental analysis, optical characterization with UV–vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.

Ross Sea paleo-ice sheet drainage and deglacial history during and since the LGM

Onshore and offshore studies show that an expanded, grounded ice sheet occupied the Ross Sea Embayment during the Last Glacial Maximum (LGM). Results from studies of till provenance and the orientation of geomorphic features on the continental shelf show that more than half of the grounded ice sheet consisted of East Antarctic ice flowing through Transantarctic Mountain (TAM) outlet glaciers; the remainder came from West Antarctica. Terrestrial data indicate little or no thickening in the upper catchment regions in both West and East Antarctica during the LGM. In contrast, evidence from the mouths of the southern and central TAM outlet glaciers indicate surface elevations between 1000 m and 1100 m (above present-day sea level). Farther north along the western margin of the Ross Ice Sheet, surface elevations reached 720 m on Ross Island, and 400 m at Terra Nova Bay. Evidence from Marie Byrd Land at the eastern margin of the ice sheet indicates that the elevation near the present-day grounding line was more than 800 m asl, while at Siple Dome in the central Ross Embayment, the surface elevation was about 950 m asl. Farther north, evidence that the ice sheet was grounded on the middle and the outer continental shelf during the LGM implies that surface elevations had to be at least 100 m above the LGM sea level. The apparent low surface profile and implied low basal shear stress in the central and eastern embayment suggests that although the ice streams may have slowed during the LGM, they remained active.Ice-sheet retreat from the western Ross Embayment during the Holocene is constrained by marine and terrestrial data. Ages from marine sediments suggest that the grounding line had retreated from its LGM outer shelf location only a few tens of kilometer to a location south of Coulman Island by ∼13 ka BP. The ice sheet margin was located in the vicinity of the Drygalski Ice Tongue by ∼11 ka BP, just north of Ross Island by ∼7.8 ka BP, and near Hatherton Glacier by ∼6.8 ka BP. Farther south, 10Be exposure ages from glacial erratics on nunataks near the mouths of Reedy, Scott and Beardmore Glaciers indicate thinning during the mid to late Holocene, but the grounding line did not reach its present position until 2 to 3 ka BP. Marine dates, which are almost exclusively Acid Insoluble Organic (AIO) dates, are consistently older than those derived from terrestrial data. However, even these ages indicate that the ice sheet experienced significant retreat after ∼13 ka BP. Geomorphic features indicate that during the final stages of ice sheet retreat ice flowing through the TAM remained grounded on the shallow western margin of Ross Sea.The timing of retreat from the central Ross Sea remains unresolved; the simplest reconstruction is to assume that the grounding line here started to retreat from the continental shelf more or less in step with the retreat from the western and eastern sectors. An alternative hypothesis, which relies on the validity of radiocarbon ages from marine sediments, is that grounded ice had retreated from the outer continental shelf prior to the LGM. More reliable ages from marine sediments in the central Ross Embayment are needed to test and validate this hypothesis.

Increase in penguin populations during the Little Ice Age in the Ross Sea, Antarctica

Penguins are an important seabird species in Antarctica and are sensitive to climate and environmental changes. Previous studies indicated that penguin populations increased when the climate became warmer and decreased when it became colder in the maritime Antarctic. Here we determined organic markers in a sediment profile collected at Cape Bird, Ross Island, high Antarctic, and reconstructed the history of Adélie penguin colonies at this location over the past 700 years. The region transformed from a seal to a penguin habitat when the Little Ice Age (LIA; 1500–1800 AD) began. Penguins then became the dominant species. Penguin populations were the highest during ca. 1490 to 1670 AD, a cold period, which is contrary to previous results in other regions much farther north. Different responses to climate change may occur at low latitudes and high latitudes in the Antarctic, even if for same species.

Iron in land-fast sea ice of McMurdo Sound derived from sediment resuspension and wind-blown dust attributes to primary productivity in the Ross Sea, Antarctica

We present high-accuracy isotope dilution mass spectrometry data on dissolved Fe (DFe), total dissolvable Fe (TD-Fe) and refractory particulate Fe (REF-Fe) concentrations in snow, land-fast ice and under-ice seawater, sampled at six sites from 14 to 22 January 2003 in Erebus Bay, McMurdo Sound. We also report refractory particulate Fe/Al ratios to help identify Fe sources. Iron concentrations in land-fast ice and snow were two to three orders of magnitude higher than the underlying seawater. Seawater Fe increased in all fractions over the sampling period (8days), likely caused by sediment resuspension induced by spring tides, which occur twice a month. We propose that entrainment of wind-blown material and sediment-derived Fe is the most important pathway for high Fe concentrations in land-fast ice in McMurdo Sound. Iron fluxes from the sediment were estimated and could fully account for the Fe inventory of the land-fast ice. Wind-blown lithogenic material in the snow on the land-fast ice makes up for 14–68% of the total Fe inventory of the sea ice. It does not appear to penetrate into the sea ice proper as snow-ice forming conditions were not present. The sources of these wind-blown particles are, in decreasing order of strength, the McMurdo Ice Shelf, the Dry Valleys, Ross Island and Erebus volcanic emissions. The data suggest that the usual spring breakup of sediment-laden land-fast ice to the Ross Sea may have a significant potential fertilizing effect on the waters of the Ross Sea Polynya. This is illustrated by the strong diminution of primary production in the Ross Sea Polynya due to the blockade of the annual sea ice breakout by the giant icebergs B-15 and C-19 during the austral summer of 2003.

Eco-environmental implications of elemental and carbon isotope distributions in ornithogenic sediments from the Ross Sea region, Antarctica

Seabirds have substantial influence on geochemical circulation of elements, serving as a link for substance exchange between their foraging area and colonies. In this study, we investigated the elemental and carbon isotopic composition of five penguin-affected sediment profiles excavated from Ross Island and Beaufort Island in the Ross Sea region, Antarctica. Among the three main constituents of the sediments (including weathered bedrock, guano and algae), guano was the main source of organic matter and nutrients, causing selective enrichment of several elements in each of the sediment profiles. In the 22 measured elements, As, Cd, Cu, P, S, Se and Zn were identified as penguin bio-elements in the Ross Sea region through statistical analysis and comparison with local end-member environmental media such as weathered bedrock, fresh guano and fresh algae. Carbon isotopic composition in the ornithogenic sediments showed a mixing feature of guano and algae. Using a two-member isotope mixing equation, we were able to reconstruct the historical change of guano input and algal bio-mass. Compared with research in other parts of Antarctic, Arctic, and South China Sea, we found apparent overlap of avian bio-elements including As, Cd, Cu, P, Se, and Zn. Information on the composition and behavior of bio-elements in seabird guano on a global scale, and the role that bio-vectors play in the geochemical circulation between land and sea, will facilitate future research on avian ecology and paleoclimatic reconstruction.

The short-term effects of surface soil disturbance on soil bacterial community structure at an experimental site near Scott Base, Antarctica

Humans are visiting Antarctica in increasing numbers, and the ecological effect of rapid soil habitat alteration due to human-induced physical disturbance is not well understood. An experimental soil disturbance trial was set up near Scott Base on Ross Island, to investigate the immediate and short-term changes to bacterial community structure, following surface soil disturbance. Three blocks, each comprising an undisturbed control, and an area disturbed by removing the top 2 cm of soil, were sampled over a time series (0, 7, 14, 21, and 35 days), to investigate changes to bacterial community structure using DNA profiling by terminal restriction fragment length polymorphism. The simulated disturbance did not cause any major shifts in the structure of the bacterial communities over the 35-day sampling period. Ordination showed that the bacterial community composition correlated strongly with soil EC (R 2 = 0.55) and soil pH (R 2 = 0.67), rather than the removal of the top 2 cm of surface material. Although the replicate blocks were visually indistinguishable from one another, high local spatial variability of soil chemical properties was found at the study site and different populations of bacterial communities occurred within 2 m of one another, within the same landscape unit. Given the current knowledge of the drivers of bacterial community structure, that is, soil EC, soil pH, and soil moisture content, a follow-up investigation incorporating DNA and RNA-based analyses over a time frame of 2–3 years would lead to a greater understanding of the effects of soil disturbance on bacterial communities.

Climate Change Winners: Receding Ice Fields Facilitate Colony Expansion and Altered Dynamics in an Adélie Penguin Metapopulation

There will be winners and losers as climate change alters the habitats of polar organisms. For an Adélie penguin (Pygoscelis adeliae) colony on Beaufort Island (Beaufort), part of a cluster of colonies in the southern Ross Sea, we report a recent population increase in response to increased nesting habitat as glaciers have receded. Emigration rates of birds banded as chicks on Beaufort to colonies on nearby Ross Island decreased after 2005 as available habitat on Beaufort increased, leading to altered dynamics of the metapopulation. Using aerial photography beginning in 1958 and modern satellite imagery, we measured change in area of available nesting habitat and population size of the Beaufort colony. Population size varied with available habitat, and both increased rapidly since the 1990s. In accord with glacial retreat, summer temperatures at nearby McMurdo Station increased by ∼0.50°C per decade since the mid-1980s. Although the Ross Sea is likely to be the last ocean with an intact ecosystem, the recent retreat of ice fields at Beaufort that resulted in increased breeding habitat exemplifies a process that has been underway in the Ross Sea during the entire Holocene. Furthermore, our results are in line with predictions that major ice shelves and glaciers will retreat rapidly elsewhere in the Antarctic, potentially leading to increased breeding habitat for Adélie penguins. Results further indicated that satellite imagery may be used to estimate large changes in Adélie penguin populations, facilitating our understanding of metapopulation dynamics and environmental factors that influence regional populations.

SNOW-WEB: a new technology for Antarctic meteorological monitoring

AbstractThis study describes SNOW-WEB, a distributed system of atmospheric sensors, which is cost-effective and can be efficiently deployed in Antarctica. The system supports traditional atmospheric sensors and has built-in redundancy as many units can be deployed in a relatively small area for a similar cost to one conventional weather station. Furthermore, each unit is equipped with wireless mesh-networking capabilities and so is able to share information with those units in its direct vicinity. This allows for the ferrying of collected information to a manned observation station and hence the ability to monitor data in real-time. GPS hardware installed on each unit also allows for high-resolution glacier or ice shelf tracking. As a testing study, eighteen such weather stations were deployed in the vicinity of Scott Base, Ross Island, Antarctica over the 2011/12 summer season. This paper reports on the successful development and deployment of the system, results from the testing period and challenges encountered during the experiment. Collected data is validated against automatic weather stations already operating in the region and an intercomparison is performed between SNOW-WEB data and forecast output from the Antarctic Mesoscale Prediction System. A high degree of agreement is found between data sources. We conclude that SNOW-WEB data is suitable for use in studies of mesoscale meteorology.

Factors determining nematode distributions at Cape Hallett and Gondwana station, Antarctica

AbstractThe distribution of nematodes at Cape Hallett and Gondwana station was found to be patchy but consistent, broad-scale habitat preferences were identified. These had been previously noted in McMurdo Dry Valleys soils and on Ross Island, indicating that habitat preferences are consistent across large scales and may play a role in determining range limits. Soil geochemistry, especially salinity, has a strong impact on distribution patterns. The distinct distribution patterns of the four species indicate different niches.Panagrolaimus davidiTimm is the only nematode that can survive within penguin rookeries, where salinity is high but bacterial food is plentiful.Scottnema lindsayaeTimm was found across the greatest range of habitats, including the driest sites and largest salinity range.Plectussp. was found in the wettest sites, with high organic content and low salinity.Eudorylaimus antarcticusSteiner (Yeates) was found at low densities and with other nematodes indicating a dependence on prey availability, an example of a biotic interaction structuring even these simplest ecosystems. Field-identifiable features could be used to identify probable nematode habitats, providing useful information for sampling and the selection of conservation areas.

Voyage to the Northwest Coast of America, 1792: Juan Francisco de la Bodega Y Quadra and the Nootka Sound Controversy by Freeman M. Tovell

 OHQ vol. 114, no. 1 nalist Fred Leeson (Rose City Justice: A Legal History of Portland, Oregon, OHS Press, 1998). Lansing and Leeson teamed up to write a history of the most populous and influential — and often controversial — county in Oregon; and while a history of an Oregon county might sound dull,Multnomah is far from it.The book is a history not only of county officials and important county commission decisions but also of natural disasters, vice crime, bribery and scandal, tragic homicide, and “Mean Girls.” The chapters are broken into small episodes, separated by virtual “meanwhiles,” very much like Lansing’s Portland. The first chapter,“The Most Important Vote of the Century,” opens in 1974 and describes the Multnomah County Commission’s decision to support a land-use plan that included light-rail transit. The chapters that follow run chronologically,beginning in 1792 with George Vancouver’s expedition and ending in 2010 with the county, like many government agencies, in financial crisis. Subsequent chapters cover the influential and sometimes controversial elections, activities, and accomplishments of the county commissioners, county sheriffs, and other memorable county officials. Readers may recognize the names Starr,Marquam,Corbett, Ladd, Holman, Bigelow, Schrunk, Gleason, Clark, Roberts, and Blumenauer. Multnomah County’s violent past is also chronicled, including the county’s first hanging in 1859, the tragic disappearance of the Martin family in 1958, and the gruesome murders of teenage sweethearts Larry Peyton and Beverly Allen in 1960. Lansing and Leeson also discuss the bidding scandal that shrouded with controversy the construction of the Ross Island and Sellwood bridges and the replacement of the Burnside Bridge. They cover in detail the vice scandal of 1956,Diane Linn’s acrimonious tenure as county commission chair from 2001 to 2006, and the frequent efforts to consolidate Multnomah County and Portland governments. Lansing and Leeson effectively use many available secondary sources. Their use of interviews, news reports, and county and state records is expected, but nevertheless impressive . The greatest value of Multnomah is as a reference work of the county’s and Portland’s often connected histories. The appendices are incredibly informative. They include the effects of Measure 5, changes to the county charter, and a chronological list of county officials. Readers will be drawn in by the stories throughout Multnomah that make up the county’s colorful past. Multnomah is well written and indexed and is recommended not only for research but also for the home library. It should sit next to MacColl,Abbott,and,well, Lansing and Leeson. Robert C. Donnelly Gonzaga University Voyage to the Northwest Coast of America, 1792: Juan Francisco de la Bodega y Quadra and the Nootka Sound Controversy translated by Freeman M. Tovell foreword by Chief Michael Maquinna The Arthur H. Clark Company, an imprint of the University of Oklahoma Press, Norman, 2012. Illustrations, maps, bibliography, index. 192 pages. $34.95 cloth. The Arthur H. Clark Company has been a publishing bastion of Western American history since 1902. This volume of Voyage to the Northwest Coast of America, 1792 is the first English-language edition of Juan Francisco de la Bodega y Quadra’s February 1793 report for the viceroy of New Spain recounting his sojourn on the northwest coast of America the previous summer and his dealings with the British explorer George Vancouver. Freeman Tovell’s translation supplements his 2008 biography of Bodega, At the Far Reaches of Empire (UBC Press). Two other experts on  Reviews Spanish exploration and empire, Robin Inglis and Iris Engstrand,have helped him bring this text to publication. Bodega’s expedition involved diplomacy, exploration, and scientific investigation. His ostensible remit was to proceed to Nootka Sound (on what is now Vancouver Island) to meet Vancouver and implement the first two articles of the Nootka Convention of 1790, which settled the diplomatic crisis between the two countries over commercial, navigation , and property rights on the West Coast of North America. The crisis was precipitated by the arrest of British fur traders by a Spanish naval officer at Nootka Sound in 1789, and Bodega was instructed to restore to the British “buildings and tracts of land”that the Spanish had supposedly confiscated there and nearby (p.15...

Erosion and transport by Byrd Glacier, Antarctica during the Last Glacial Maximum

Glacial till samples from seven, modern-Holocene Byrd Glacier moraines were characterized using particle size analysis, sand petrography and detrital zircon geochronology and compared to Ross Sea tills deposited during the Last Glacial Maximum. The goal was to identify the paleoflow path for Byrd Glacier and assess the use of multiple provenance techniques. The coarse sand fraction of Byrd Glacier tills is dominated by lithic fragments of adjacent bedrock outcrops, except samples from the Lonewolf Nunataks, which have a higher proportion of mineral to lithic fragments, as well as a recognizable exotic component. Cluster analysis shows that Byrd Glacier tills, with the exception of the two Lonewolf Nunataks sites, do not cluster strongly with Ross Sea samples because they have a higher proportion of lithic fragments. This indicates that comminution must be an active subglacial process beneath East Antarctic outlet glaciers. Byrd Glacier tills are also typically coarser grained that Ross Sea tills and their maturity is a reflection of both glacial processes and rock type. Measured U/Pb ages of detrital zircons from Byrd Glacier tills range from Triassic to Archean (240–3540 Ma) with a dominance of grains 530–600 Ma. Ross Sea till samples show spatial variability in U/Pb age distributions, with the core sites west of the 180° longitude line showing similarity to most Byrd Glacier tills, whereas core NBP9407-39, east of 180° long., is dominated by ∼100 Ma grains. Ross Sea tills also contain a recognizable detrital zircon fraction eroded inland of the Transantarctic Mountains. Both provenance methods indicate that the ice flow line for Byrd Glacier during the LGM was to the east of Ross Island and extended on either side of Ross Bank, with the majority of ice flowing to the Ross Sea's Central Basin. Our analysis shows that sand petrography and detrital zircon U/Pb age spectra provide complementary datasets that produce similar ice flow reconstructions and reveal valuable information about glacial processes and ice covered bedrock.

Changes in physiological responses of an Antarctic fish, the emerald rock cod (Trematomus bernacchii), following exposure to polybrominated diphenyl ethers (PBDEs)

Although polybrominated diphenyl ethers (PBDEs) have the ability to undergo long-range atmospheric transport to remote ecosystems like Antarctica, a recent study found evidence for a local source within the Antarctic. PBDEs from sewage treatment outfalls of McMurdo Station and Scott Base on Ross Island have been attributed to the high concentrations measured in emerald rock cod (Trematomus bernacchii). The potential impact of PBDEs on Antarctic fish physiology is unknown and therefore, the aim of this study was to obtain a greater understanding of physiological responses of emerald rock cod for assessing changes in ecosystem quality. A PBDE mixture (ΣPBDE 8 congeners) was administered fortnightly over 42 days and physiological changes were observed throughout this period and for a further 14 days thereafter. Changes in liver composition, molecular level changes and enzyme activities of selected detoxification-mediated and antioxidant defence markers were measured. Changes in total lipid, lipid peroxide and protein carbonyl concentrations in emerald rock cod liver were consistent with increases in nucleus surface area in the PBDE-treated groups, suggesting alterations in cellular function. Changes in the activities of selected antioxidant enzymes indirectly indicated oxidative stress, possibly resulting in the changes in liver composition. Additionally, glutathione-S-transferase (GST) activity reached its peak faster than that of ethoxyresorufin-O-deethylase (EROD), suggesting that during the early response to PBDE exposures there could be a greater involvement of GST-mediated detoxification. Thus, for at least the species examined here, protein carbonyl and lipid peroxides were useful and informative biomarkers for cellular level responses following PBDE-related exposure. Furthermore, our findings suggest that emerald rock cod exposed to PBDEs develop oxidative stress – a condition with potential consequences for fish growth, health and reproduction.

Dynamics of the Foehn Mechanism in the McMurdo Dry Valleys of Antarctica from Polar WRF

AbstractFoehn events over the McMurdo Dry Valleys (MDVs), the largest ice‐free region of Antarctica, promote glacial melt that supports biological activity in the lakes, streams, rocks and soils. Although MDVs foehn events are known to depend upon the synoptic‐scale circulation, the physical processes responsible for foehn events are unknown. A polar‐optimized version of the Weather Research and Forecasting model (Polar WRF) is used for a case study of a representative summer foehn event from 29 December 2006 to 1 January 2007 in order to identify and explain the MDVs foehn mechanism. Pressure differences across an elevated mountain gap upstream of the MDVs provide forcing for southerly flow into the western, upvalley entrance of the MDVs. Complex terrain over the elevated gap and the MDVs leads to mountain wave effects such as leeside acceleration, hydraulic jumps, wave breaking and critical layers. These mountain wave effects depend on the ambient (geostrophic) wind direction. Pressure‐driven channelling then brings the warm, dry foehn air downvalley to eastern MDV sites. Brief easterly intrusions of maritime air into the eastern MDVs during foehn events previously have been attributed to either a sea‐breeze effect in summer or local cold‐pooling effects in winter. In this particular case, the easterly intrusions result from blocking effects of nearby Ross Island and the adjacent Antarctic coast. Temperature variability during the summer foehn event, which is important for meltwater production and biological activity when it exceeds 0°C, primarily depends on the source airmass rather than differences in foehn dynamics.

A method for assessing the physical recovery of Antarctic desert pavements following human-induced disturbances: A case study in the Ross Sea region of Antarctica

With increasing visitor numbers an understanding of the impacts of human activities in Antarctic terrestrial environments has become important. The objective of this study was to develop a means for assessing recovery of the ground surface desert pavement following physical disturbance. A set of 11 criteria were identified to assess desert pavement recovery. Assessed criteria were: embeddedness of surface clasts; impressions of removed clasts; degree of clast surface weathering; % overturned clasts; salt on underside of clasts; development of salt coatings; armouring per m2; colour contrast; evidence of subsidence/melt out; accumulation of salt on cut surfaces; and evidence of patterned ground development. Recovery criteria were assigned a severity/extent rating on a scale from zero to four, zero being highly disturbed, and four being undisturbed. A relative % recovery for each criteria was calculated for each site by comparison with a nearby undisturbed control area, and an overall Mean Recovery Index (MRI) was assigned to each pavement surface.To test the method, 54 sites in the Ross Sea region of Antarctica were investigated including areas disturbed by: bulldozer scraping for road-fill, contouring for infrastructure, geotechnical investigations, and experimental treading trial sites. Disturbances had occurred at timescales ranging from one week to 50 years prior to assessment. The extent of desert pavement recovery at the sites investigated in this study was higher than anticipated. Fifty of the 54 sites investigated were in an intermediate, or higher, stage of desert pavement recovery, 30 sites were in an advanced stage of recovery, and four sites were indistinguishable from adjacent control sites (MRI = 100%). It was found that active surfaces, such as the gravel beach deposits at the Greenpeace World Park Base site at Cape Evans, the aeolian sand deposits at Bull Pass, and the alluvial fan deposits of the Loop Moraine field campsite, recovered relatively quickly, whereas less active sites, such as the bulldozed tracks at Marble Point, and Williams Field to McMurdo Station pipeline site on Ross Island, showed only intermediate recovery 20–30 years after disturbance. The slabby grano-diorite surface material at the former Vanda Station site, meant that the impacts that had occurred were hard to detect following decommissioning of the station and site remediation. Desert pavements disturbed by randomly dispersed footprints, temporary field campsites at the Loop Moraine and VXE6 Pond in the Wright Valley, recovered to be undetectable (MRI = 100%) within five years, whereas track formation from repeated trampling, particularly the concentration of larger clasts along the margin of a confined track, persisted for over 15 years (MRI = 82%). The recovery assessment method developed in this study has environmental management applications and potential to advance our ability to predict the recovery of desert pavement following human impacts from activities in Antarctica.

Revision of type materials of antarctic diatom species (Bacillariophyta) described by West & West (1911), with the description of two new species.

In 1911, W. & G.S. West published a detailed account of freshwater algae collected by James Murray in the vicinity of Cape Royds on Ross Island (Antarctic Continent). Out of of 84 algal taxa reported, 30 were diatoms. Although the majority of the diatoms were considered (at that time) to be cosmopolitan, eight diatom species and two varieties were described as new. While most of these new taxa are still commonly reported from Antarctic and Subantarctic localities, the exact identity of some remains uncertain. Here we document the morphology of these species from the original type material using light and scanning electron microscopy; the taxonomic identities are discussed and, where necessary, the taxonomy is updated. For several species, lectotypes are designated. In addition, two Antarctic species are described as new: Luticola pseudomurrayi Van de Vijver et Tavernier sp. nov. and Chamaepinnularia gibsonii Van de Vijver sp. nov.

A new interpretative approach to the chemistry of copper-alloy objects: source, recycling and technology

The metal composition of bronze alloys has been routinely examined as a means of inferring the source of the ore. But bronze is recycled, and the quantity of some components, such as arsenic, is depleted every time the alloy is melted down. Since the Early Bronze Age of the British Isles was largely supplied from a single mine on Ross Island, Co. Kerry, tracking arsenic content shows the number of re-melts and this gives the object a biography and a social context. Applying this ingenious new procedure to their large database, the authors also winkle out other sources of supply and new insights about the technology involved.

A 16,000-yr tephra framework for the Antarctic ice sheet: a contribution from the new Talos Dome core

A detailed tephra record for the last 16,000 years of the TALDICE ice core drilled at Talos Dome (East Antarctica, Pacific/Ross Sea sector) is documented. Traces of 26 different explosive volcanic eruptions, dated by ice core chronology and framed within the climate (δ18O) record for the core, have been identified. Glass major element composition and grain size data indicate that all prominent tephra layers derive from Antarctic volcanic activity and likely originated in proximal volcanoes of the Melbourne Volcanic Province (Northern Victoria Land). Two other Antarctic horizons may have originated from the more distant volcanoes of Mount Berlin (Marie Byrd Land, West Antarctica) and Mount Erebus (Ross Island, Southern Victoria Land). Moreover, based on glass-shard geochemistry and a 20-year analysis of atmospheric back trajectories suggesting ash transport from South America to the drilling site by the circumpolar westerly circulation, a few faint microtephra horizons are attributed to Andean volcanic activity. Two of these tephras are interpreted to be related to known Holocene explosive eruptions from the volcanoes of Mount Hudson and Mount Burney. Finally, by comparing compositional features in conjunction with age data, three TALDICE tephras have been successfully correlated with volcanic layers in other ice records of the Antarctic ice sheet. Altogether, our results expand the Antarctic tephrostratigraphic framework and add value to the prospects for continental-scale correlations between ice cores and Southern Hemisphere sediment archives.

A diatom record of late Pliocene cooling from the Ross Sea continental shelf, AND-1B, Antarctica

A late Pliocene – early Pleistocene, 2.9–2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the Southern Ocean oceanic fronts based on DSDP/ODP diatom biostratigraphic data to evaluate paleoenvironmental change for the 2.9–2.0Ma interval of the AND-1B core. The diatom assemblages from AND-1B record a progressive environmental change through the late Pliocene–early Pleistocene. A relatively warm period with potential SST of up to 4°C at ca. 2.9Ma was succeeded by a reduction of warm water species and an increase of taxa associated with more southerly water masses until 2.58Ma (at isotope stage G1). Younger, early Pleistocene, diatomaceous units are dominated by extinct Rouxia, Thalassiosira species and newly described Fragilariopsis species indicative of cold open water and drift ice. The last recorded cooling step occurs at the top of the interval studied (ca 2.0) Ma indicated by the trace abundance of Fragilariopsis and Actinocyclus species present in modern sea ice assemblages but absent in the late Pliocene–early Pleistocene AND-1B record, even though many of its species had their first occurrences during the Pliocene. The extant sea ice assemblage occurs with an abundance of 2–29% (average 10%) in the late Pliocene–early Pleistocene AND-1B record implying that the modern sea ice and ice shelf polar conditions were not established within the studied interval. The most frequently applied sea ice indicator, Fragilariopsis curta, is consistently present in low to moderate abundance (1–22%) together with Chaetoceros resting spores (2–30%) through the 2.9–2.0Ma interval. The diatom assemblage shifts indicate a dynamic environment with an overall trend towards colder conditions after ca. 2.6Ma but does not reach the Holocene configuration.

Ice-flow switching and East/West Antarctic Ice Sheet roles in glaciation of the western Ross Sea

The long-term behavior of the East and West Antarctic Ice Sheets, and their respective responses to forcing provide essential context for assessment of modern dynamic changes in ice-flow regimes and ice-sheet and shelf margins. The western Ross Sea discharges ice from both the East and West Antarctic Ice Sheets, and the paleoglacial record from this region is therefore valuable in unraveling their long-term behavior. New, high-resolution multibeam bathymetric data reveal snapshots of well-preserved glacial landforms on the seafloor around Ross Island and McMurdo Sound. Glacial lineations, grounding zone wedges, draped recessional moraines, and meltwater channels record a series of different ice-flow events in the region, contradictions between which require major phases of ice-flow reorganization. From the glacial geomorphology, we reconstruct a four-stage model of ice-flow evolution for the last glacial cycle, consisting of: (1) northeastward flow into the Ross Sea from McMurdo Sound; (2) westward flow from the Ross Sea, around Ross Island, and onto the Victoria Land coast and coastal seafloor trough; (3) a deglacial phase of ice-sheet thinning, minor shifts in flow, and grounding line retreat into McMurdo Sound; and (4) grounding line pinning on Ross Island during regional retreat, uncoupling of a remnant Ross Island ice cap, and local oscillation of Victoria Land outlet glaciers. We find that East Antarctic Ice Sheet ice discharge had a strong influence on ice-flow geometry in this part of the Ross Sea during the last glacial stage, but that it was not necessarily in phase with the behavior of the West Antarctic Ice Sheet. It is similarly evident that the ice streams that drained the Ross Sea over the continental shelf at the Last Glacial Maximum did not all operate synchronously, and exerted different drawdown power at different times. Finally, we conclude that Ross Island acts as an important pinning point in the Ross Sea ice-sheet-shelf system, stabilizing grounding line retreat and encouraging lasting ice-shelf development.