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There are limited data on the sensitivity to contaminants of marine organisms in polar regions. Consequently, assessments of the risk of contaminants to marine biota in polar environments typically include extrapolations from temperate and/or tropical species. This is problematic because the taxonomic composition of organisms differs between polar and temperate/tropical waters, and both the toxicity of chemicals and the physiology of organisms are very different at the stable low temperatures experienced in polar marine systems. Collecting high-quality sensitivity data for a wide range of marine polar organisms using traditional toxicity assessment approaches is a time-consuming and difficult process, especially in remote and hostile environments. We applied a rapid toxicity testing approach, which allowed a much larger number of species to be tested than would be possible with traditional toxicity test methods, albeit with lower replications and fewer exposure concentrations. With this rapid approach, sensitivity estimates are less precise, but more numerous. This is important when constructing species sensitivity distributions (SSDs), which aim to represent the sensitivity of communities. We determined the approximate sensitivity (4- and 10-d median lethal concentration [LC50] values) of a large and representative sample of Antarctic marine invertebrates to copper (Cu), zinc (Zn), and cadmium (Cd). Up to 88 LC50 values (from 88 different taxa) were used in the construction of SSDs. The hazardous concentrations for 1% of taxa (HC1) based on 10-d LC50 values were 37, 346, and 792 μg/L for Cu, Zn, and Cd, respectively. Our results provide a basis for estimating the risk of exposure to metals for a large representative sample of marine polar invertebrates. Environ Toxicol Chem 2019;38:1560-1568. © 2019 SETAC.

Shelf-incising canyons on the upper continental slope are important conduits for the export of dense, organic-rich shelf waters from the East Antarctic margin. This interaction of geomorphic features and oceanography plays an important role in controlling benthic community composition in this environment. Dense hydrocoral–sponge communities have been identified at new sites within a shelf-incising canyon on the upper continental slope (430–640 m) off George V Land, East Antarctica, adjacent to sites previously identified and declared Vulnerable Marine Ecosystems by the Commission for the Conservation of Antarctic Marine Living Resources. Sparse hydrocoral communities were also found at several sites along the continental slope receiving dense shelf waters. These findings provide further evidence of hydrocoral communities along the George V Land slope and support previous hypotheses regarding the importance of Antarctic Bottom Water export from the shelf providing an abundant food source for the benthos within shelf-incising canyons.

An integrated analysis of biological and geoscientific data collected from the nearshore marine environment of the Vestfold Hills was used to identify benthic habitats and associated communities and examine relationships between benthic community composition and environmental characteristics. A 48 km2 area was surveyed using a multibeam echosounder system (MBES) to produce high-resolution bathymetry and backscatter intensity maps of the seabed. Epibenthic community data and in situ observations of substrate composition and seafloor bedforms and features were obtained from towed underwater video. A comparison of top-down and bottom-up approaches to defining benthic habitats was used to improve understanding of the applicability of mapping methodologies. On a broad scale, both approaches produced habitat classes distinguished largely by geomorphic features, with substrate and depth identified as the main controls of benthic community composition, however, the relationship between benthic community composition and environmental characteristics is complex with many variables contributing to differences in community composition. The top-down approach was based on geomorphic units defined using abiotic characteristics and the assemblages identified within the geomorphic were very broad with only weak distinction between assemblages. Conversely, the bottom-up approach generated additional habitat classes, identified clear defining taxa for each class, greater distinction between the benthic communities, and allowed identification of additional environmental factors (i.e. sea ice cover) that influence benthic community distribution that are not discernible from geomorphic information alone. The habitat types identified and mapped using the bottom-up approach include shallow boulder fields and exposed bedrock which are dominated by dense macroalgae communities, and steep slopes, muddy basins and sandy plains which are dominated by invertebrate communities. The results indicate that a bottom-up approach is preferable for benthic habitat mapping, however, where detailed information is not available, geomorphic information provides a reasonable indication of the distribution of benthic habitats and communities. This study highlights the utility of multibeam sonar for interpretation of seafloor morphology and substrate and the multibeam data provide a physical framework for understanding benthic habitats and the distribution of benthic communities. This research provides the scientific context and spatial framework for managing the Vestfold Hills nearshore marine environment and provides a baseline for assessing environmental change.

A survey of nearshore areas in the Vestfold Hills, Antarctica, using high-resolution multibeam swath bathymetry provided both a detailed digital bathymetric model and information on sediment acoustic backscatter. Combined with underwater video transects and sediment sampling, these data were used to identify and map geomorphic units. Six geomorphic units identified in the survey region include: rocky outcrops, basins, pediments, valleys, scarps and embayments. In addition to geomorphic units, the data revealed sedimentary features that provide insights into post-glacial sediment transport and erosion in the area. Ice keel pits and scours are common, and sea floor channels, scour depressions and sand ribbons indicate transport and deposition by wind-driven currents and oceanographic circulation. Gullies and sediment lobes observed on steep slopes indicate mass movement of sediment. Some of these processes have not been directly observed to date, but their effectiveness in shaping the modern sea floor is clearly indicated by the sea floor mapping data. The embayments preserve a mantle of boulder sand probably deposited by cold-based glaciers which were flanked by faster-flowing ice in adjoining regions.

Human impacts threaten not only species, but also entire ecosystems. Ecosystems under stress can collapse or transition into different states, potentially reducing biodiversity at a variety of scales. Here we examine the vulnerability of Antarctic shallow invertebrate-dominated ecosystems, which may be threatened for several reasons.These unique shallow-water communities mostly consist of dark-adapted invertebrates, and rely on sea ice to create low-light marine environments. Climate change is likely to cause early breakout of seasonal sea ice in parts of Antarctica, which will dramatically increase the amount of light reaching shallow seabed. This is predicted to result in ecological regime shifts, in which invertebrate-dominated communities are replaced by macroalgal beds. Habitat for these endemic Antarctic ecosystems is globally rare, and the fragmented nature of their distribution along Antarctic coast increases their sensitivity to change. Concurrently, human activities in Antarctica are concentrated in areas where these habitats occur, compounding potential impacts. While there are clear mechanisms of threat to these ecosystems, lack of knowledge about their spatial distribution obscures predictions of potential ecosystem loss, and the likelihood of recovery. In this paper we describe these ecosystems, their association with the environment and the reasons for their vulnerability.We estimate their spatial distribution around Antarctica using sea ice and bathymetric data, and apply the International Union for Conservation of Nature Red List of Ecosystems criteria to assess their vulnerability. Best available data suggest that shallow ice-covered ecosystems are likely Near Threatened to Vulnerable in places, although the magnitude of risk is spatially variable and requires additional data to strengthen the assessment.

A shoreline waste disposal site at Casey Station, Antarctica was removed because it was causing impacts in the adjacent marine environment (Brown Bay). We conducted a field experiment to determine whether the excavation created further impacts. Trays of clean, defaunated sediment were deployed at two locations within Brown Bay and two control locations, two years prior to remediation. Trays were sampled one year before, 1 month before, 1 month after and two years after the excavation. An increase in metals was found at Brown Bay two years after the remediation. However there was little evidence of impacts on sediment assemblages. Communities at each location were different, but differences from before to after the remediation were comparable, indicating there were unlikely to have been further impacts. We demonstrate that abandoned waste disposal sites in hydrologically active places in Antarctica can be removed without creating greater adverse impacts to ecosystems downstream.

The surface sedimentary record from six cores collected from beneath the Amery Ice Shelf, East Antarctica, provides a unique view of the sedimentary and oceanographic processes in this sub-ice shelf setting. The composition and age of the surface sediments indicate spatial variations in ice shelf cavity–ocean interaction, which are consistent with patterns of ocean inflow and outflow modelled and observed beneath the ice shelf. Sediments within 100 km of the ice shelf front (site AM01) show the greatest open ocean influence with a young surface age and the highest total diatom abundance, compared to older ages and lower diatom abundances at sites deeper in the cavity (AM03–AM06). The variable marine influence between sites determines the nature of benthic communities. Seabed imagery indicates the existence of sessile suspension feeders in areas of strong marine inflow (site AM01b), while grazers, deposit feeders and a few suspension feeders occur at sites more distal from the shelf calving front where the food supply is lower (sites AM03 and AM04). Understanding the sedimentary and oceanographic processes within the sub-ice shelf environment allows better constraint of interpretations of down core sediment records, an improved understanding of the nature of biological communities in sub-ice shelf environments, and a baseline for determining the sensitivity of the system to any future changes in ocean dynamics.

On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics.

We present a comprehensive scientific assessment of the environmental impacts of an Antarctic wastewater ocean outfall, at Davis station in East Antarctica. We assessed the effectiveness of current wastewater treatment and disposal requirements under the Protocol on Environmental Protection to the Antarctic Treaty. Macerated wastewater has been discharged from an outfall at Davis since the failure of the secondary treatment plant in 2005. Water, sediment and wildlife were tested for presence of human enteric bacteria and antibiotic resistance mechanisms. Epibiotic and sediment macrofaunal communities were tested for differences between sites near the outfall and controls. Local fish were examined for evidence of histopathological abnormalities. Sediments, fish and gastropods were tested for uptake of sewage as measured by stable isotopes of N and C. Escherichia coli carrying antibiotic resistance determinants were found in water, sediments and wildlife (the filter feeding bivalve Laternula eliptica). Fish (Trematomus bernacchii) within close proximity to the outfall had significantly more severe and greater occurrences of histopathological abnormalities than at controls, consistent with exposure to sewage. There was significant enrichment of 15N in T. bernacchii and the predatory gastropod Neobuccinum eatoni around the outfall, providing evidence of uptake of sewage. There were significant differences between epibiotic and sediment macrofaunal communities at control and outfall sites (

We performed a metagenomic survey (6.6 Gbp of 454 sequence data) of Southern Ocean (SO) microorganisms during the austral summer of 2007–2008, examining the genomic signatures of communities across a latitudinal transect from Hobart (44°S) to the Mertz Glacier, Antarctica (67°S). Operational taxonomic units (OTUs) of the SAR11 and SAR116 clades and the cyanobacterial genera Prochlorococcus and Synechococcus were strongly overrepresented north of the Polar Front (PF). Conversely, OTUs of the Gammaproteobacterial Sulfur Oxidizer-EOSA-1 (GSO-EOSA-1) complex, the phyla Bacteroidetes and Verrucomicrobia and order Rhodobacterales were characteristic of waters south of the PF. Functions enriched south of the PF included a range of transporters, sulfur reduction and histidine degradation to glutamate, while branched-chain amino acid transport, nucleic acid biosynthesis and methionine salvage were overrepresented north of the PF. The taxonomic and functional characteristics suggested a shift of primary production from cyanobacteria in the north to eukaryotic phytoplankton in the south, and reflected the different trophic statuses of the two regions. The study provides a new level of understanding about SO microbial communities, describing the contrasting taxonomic and functional characteristics of microbial assemblages either side of the PF.

Photosynthetic activity of marine macroalgae in the Windmill Islands, East Antarctica, was measured in situ using submersible modulated fluorometers. An empirical relation incorporating terms for respiration and non-linear electron transport was derived from simultaneous in vivo measurements of effective quantum yield ( ) and oxygen evolution. This relation was used with in situ measurements of and photosynthetic photon flux density acquired over 24-h periods to estimate oxygen evolution rates of algae over the course of the measurement period. Productivity ranged from −8 to 19 µmol O2 g−1 FW h−1 (FW = fresh weight), with daily carbon gain ranging from −1.5 to 3.6 mg C g−1 FW d−1 for midnight ice-covered algae and midday ice-free algae, respectively. These values were similar to published values of productivity of Antarctic species derived from oxygen- and carbon-based techniques. The technique described here provides a simple and rapid means of estimating primary productivity in marine systems.

The comatulid crinoid Anthometrina adriani is well represented among the suspension-feeding megaepibenthos from the continental shelf of the Dumont D'Urville Sea, Antarctica. Nearly 500 specimens were sampled during the Collaborative East Antarctic Marine Census expedition onboard the RV 'Aurora Australis' (December 2007 to January 2008), from 50 of the 87 stations over a 400 km² area. Abiotic environmental factors were measured and an ocean circulation model was used to generate near-bottom parameters. The ecological niche of A. adri- ani was described by using ecological-niche factor analysis and Mahalanobis distances factor analysis. An environmental suitability map (ESM) was developed to map the optimal habitat. A. adriani prefers moderately deep and relatively cold waters with moderate current velocity, and a substrate with low gravel content and biogenic carbonate. The ESM shows 4 optimal regions: the eastern side of the George V Basin, the eastern side of the Adelie Basin, the southern part of the Adelie Bank, and the coastal area between the Astrolabe and Mertz glaciers. The ecological niche for A. adriani appears very narrow, but the species is widely distributed across the Antarctic shelf. It suggests that local changes in limiting factors have a strong local effect on the distribution of this species and that a total eradication of this species from the shelf would need an Antarctic-wide and synchronic change in these essential parameters. Modeling modifications in environmental conditions under different climate change scenarios could help predict the effect of such changes on the distribution of this selective species.

The RSV Aurora Australis survey allowed the first comprehensive study of the demersal ichthyofaunal environment and of the diversity of the Dumont d’Urville Sea. We observed a high dominance of the Notothenioidei in both the number of species and in integrated abundances. The Nototheniidae was the most abundant family with 44.7% of the total integrated abundance, followed by Bathydraconidae (18.8%). Trematomus eulepidotus was the dominant species with 19.9% of the total individuals catch. Nevertheless, 43 of the 53 species caught could be considered as very rare. The Bathydraconidae was the most diversified family with 11 species caught. The highest integrated abundances of fish were found from 400 to 800 m. Well-structured species communities were observed, with high species richness from 570 to 681 m. The richest zones were located along the basins and along their upper-sides. Statistical analyses indicated large-scale spatial patterns in species composition, with clear differences in fish communities from the continental slopes, the basins and on the shelf. At a finer spatial scale, the current in the George V Basin and iceberg scouring on the banks and their sides tended to create locally heterogeneous small-scale habitats. We suggest that the glacial history and the structured habitats allowed successive colonisations of the seabed by demersal fish.

The Census for Antarctic Marine Life (CAML, IPY Project 53) aimed to investigate the distribution and abundance of Antarctic marine biodiversity and how it will be affected by climate change. It was a major ship-based research programme in the austral summer of 2007-2008 involving scientists from 30 countries and 19 vessels. The Collaborative East Antarctic Marine Census (CEAMARC) was a multinational contribution to CAML involving scientists and students from several nations using three ships from Australia, Japan and France surveying the one area. This collaboration was a highly coordinated and comprehensive survey of the plankton, fish, benthos, oceanography and geophysical conditions of the waters north of Terre Adelie and George V Land of Eastern Antarctica. CEAMARC has provided a robust benchmark of the marine life in this poorly studied sector and will help to establish the monitoring of future changes in this region. Crown Copyright (C) 2011 Published by Elsevier B.V. and NIPR. All rights reserved.

The quantum yield of chlorophyll a fluorescence of an Antarctic macroalga, Iridaea cordata, was measured in situ using logging fluorometers with an automated dark-acclimation capability throughout several diel periods. Application of far-red light and dark acclimation enabled the automated determination of photochemical quenching and non-photochemical quenching parameters that have until recently been restricted to manual measurement in terrestrial and shallow water environments. Our results show that non-photochemical quenching processes in Iridaea thalli that have been exposed to moderately high irradiances during the day, take all night to relax. We also show that, for algae exposed to relatively high light during the day, around 30–40% of total excitation flux is allocated to basal intrinsic non-radiative decay processes, with the remainder allocated to downregulation or photochemistry. The ability to evaluate the allocation of energy to these fundamentally different non-photochemical quenching proces...

Transient white and grey mats were observed in depressions and enclosed basins in marine sediment in the Windmill Islands, East Antarctica. These patches have not been described in the Antarctic marine environment previously although a similar phenomenon has been described in the Arctic. Our aim was to describe the sediment geochemical and biological properties inside the patches and to determine their similarity to each other. We compared the benthic infaunal communities and the chemical properties of the sediment in the white patches to nearby sediment without white mats. We observed differences in sediment pH, Eh and elemental concentrations inside and outside patches. The benthic infaunal communities inside the patches were significantly different, lower in abundance and diversity, compared to outside the patches. The structure of the microbial communities within the mats was described by constructing clone libraries from four different patches. These clone libraries were dominated by bacteria from the bacteroidetes phylum. Clones closely related to sulphur-oxidising bacteria from the gammaproteobacteria and/or the epsilonproteobacteria were present in all libraries. This is the first detailed description of these patches in the Antarctic and demonstrates the link between physico-chemical factors and microbial and infaunal community structure. It appears that this phenomenon may be driven by the formation and persistence of sea-ice, and as both the spatial extent of sea-ice and its persistence in polar regions are likely to change under predicted climate change scenarios, we suggest this is a previously undocumented mechanism for climate change to impact polar ecosystems.

Physical and biological characteristics of benthic communities are analysed from underwater video footage collected across the George V Shelf during the 2007/2008 CEAMARC voyage. Benthic habitats are strongly structured by physical processes operating over a range of temporal and spatial scales. Iceberg scouring recurs over timescales of years to centuries along shallower parts of the shelf, creating communities in various stages of maturity and recolonisation. Upwelling of modified circumpolar deep water (MCDW) onto the outer shelf and cross-shelf flow of high-salinity shelf water (HSSW) create spatial contrasts in nutrient and sediment supply, which are largely reflected in the distribution of deposit- and filter-feeding communities. Long-term cycles in the advance and retreat of icesheets (over millennial scales) and subsequent focussing of sediments in troughs such as the Mertz Drift create patches of consolidated and soft sediments, which also provide distinct habitats for colonisation by different biota. These physical processes of iceberg scouring, current regimes and depositional environments, in addition to water depth, are important factors in the structure of benthic communities across the George V Shelf. The modern shelf communities mapped in this study largely represent colonisation over the past 8000–12,000 years, following retreat of the icesheet and glaciers at the end of the last glaciation. Recolonisation on this shelf may have occurred from two sources: deep-sea environments and possible shelf refugia on the Mertz and Adelie Banks. However, any open-shelf area would have been subject to intense iceberg scouring. Understanding the timescales over which shelf communities have evolved and the physical factors which shape them will allow better prediction of the distribution of Antarctic shelf communities and their vulnerability to change. This knowledge can aid better management regimes for the Antarctic margin.

We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining.

A 5 yr field experiment was carried out comparing the effects of Special Antarctic Blend (SAB) diesel, synthetic lubricant (Mobil 0W40), used synthetic lubricant (used Mobil 0W40) and a biodegradable lubricant (Titan GT1) on Antarctic benthic microbial communities. Sediment from an uncontaminated site was collected, spiked with one of the oils and deployed in O’Brien Bay, East Antarctica. Sediment samples were then collected over 5 yr. All the oils caused changes in the microbial community in the top 1 cm of sediment, as determined by 16S ribosomal ribonucleic acid (rRNA) gene-based terminal restriction fragment length polymorphism analysis. The greatest effect was observed in the SAB diesel treatment. The biodegradable oil did not have a significant effect on the communities initially, but the communities present at 2 and 5 yr were significantly different to the controls. The unused and used lubricants were both significantly different to the control treatment. All the oils degraded, with 39% of the SAB, 15% of the unused lubricant, 15% of the used lubricant and 12% of the biodegradable oil, remaining after 5 yr. These results show that the effects of all these oils will be evident in the Antarctic benthic ecosystem for longer than 5 yr. This highlights the need for studies into the longevity and ecotoxicology of oil products in the Antarctic environment.

Sediment profiles for pH, Eh, 28 elements, water and organic content are presented here for human impacted and reference locations in the Windmill Islands, East Antarctica. Variations in element concentrations are observed with increasing depth, especially at Brown Bay where the impact of past human activities is most pronounced in the top 10 cm. Spatial differences were observed between sediment profiles at reference and impacted locations and were largely explained by Pb variability in the top 5 cm. Median element concentrations from surface, middle and bottom regions of the sediment profile were compared to composite sample medians (no depth stratigraphy) for 11 elements at O'Brien Bay (reference) and Brown Bay (impacted). Pronounced differences were observed for Brown Bay, particularly surface and middle sections, implying that composite samples dilute the near surface anthropogenic signal by mixing with deeper uncontaminated sediment.

Dense coral-sponge communities on the upper continental slope at 570–950 m off George V Land, East Antarctica have been identified as Vulnerable Marine Ecosystems. The challenge is now to understand their probable distribution on other parts of the Antarctic margin. We propose three main factors governing their distribution on the George V margin: 1) their depth in relation to iceberg scouring, 2) the flow of organic-rich bottom waters, and 3) their location at the head of shelf cutting canyons. Icebergs scour to 500 m in this region and the lack of such disturbance is a probable factor allowing the growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons which receive descending plumes of Antarctic Bottom Water formed on the George V shelf, which could entrain abundant food for the benthos. The canyons harbouring rich benthos are also those that cut the shelf break. Such canyons are known sites of high productivity in other areas due to strong current flow and increased mixing with shelf waters, and the abrupt, complex topography. These proposed mechanisms provide a framework for the identification of areas where there is a higher likelihood of encountering these Vulnerable Marine Ecosystems.

Bacterial community structures in soils collected from eight sites around Casey Station, Antarctica, were investigated using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA gene fragments. Higher bacterial diversity was found in soils from protected or relatively low human-impacted sites in comparison to highly impacted sites. However, the highest diversity was detected in samples from Wilkes Tip, a former waste disposal site that has been undisturbed for the last 50 years. Comparison of community structure based on non-metric multidimensional scaling plots revealed that all sites, except the hydrocarbon-contaminated (oil spill) site, were clustered with a 45% similarity. A total of 23 partial 16S rRNA gene sequences were obtained from the excised DGGE bands, with the majority of the sequences closely related to those of the Cytophaga–Flexibacter–Bacteroides group. No significant correlation was established between environmental variables, including soil pH, electrical conductivity, carbon, nitrogen, water content and heavy metals, with bacterial diversity across the eight study sites.

Chlorophyll fluorescence was used to measure changes in the maximum fluorescence yield ( ) and effective quantum yield (ΔF/ ) of Antarctic macroalgae in response to dissolved copper. Single-point measurements of ΔF/ of Desmarestia menziesii in concentration-response experiments were used to define the concentration where ΔF/ declined by 50% (EC50) after 6 h of exposure (3.9 mg L−1 ± 23% coefficient of variation (CV)). Fluorescence imaging experiments with the laminar algae Iridaea mawsonii and Himantothallus grandifolius neither showed any consistent pattern in spatial heterogeneity of fluorescence response, nor could EC50 values be obtained. However, imaging experiments on the terete D. menziesii resolved heterogeneity in fluorescence responses to dissolved copper with parameters declining more rapidly for thin thalli than thick thalli. While ΔF/ of thick thalli declined significantly after 7 days and provided an EC50 of 1.1 mg L−1 ± 29% CV, declining provide a lower and more precise nominal EC50 estimat...

Although long-range atmospheric transport has been described as the predominant mechanism for exposing polar regions to persistent organic pollutants (POPs), recent studies have suggested that bird activity can also contribute substantially to contaminant levels in some environments. However, because the species so far reported have all been migratory, it has not been demonstrated conclusively whether locally elevated contamination represents transport from lower latitudes by the migrating birds or, alternatively, redistribution and concentration of contaminants that were already present in the high-latitude environments. The present study demonstrates, for the first time, that several POPs are present in elevated concentrations in an environment frequented by a non-migratory species (Adelie penguins) that spends its entire life in the Antarctic. Levels of POPs, such as p,p′-DDE, hexachlorobenzene (HCB), chlordanes (CHLs) and polychlorinated biphenyls (PCBs), were 10 to 100-fold higher in soil samples from penguin colonies than from reference areas. This significant difference is likely related to local penguin activity, such as a higher abundance of guano and the presence of bird carcasses. This hypothesis is also supported by a higher percentage of persistent congeners (PCB 99, 118, 138 and 153) in the soil from the colonies compared to the reference areas. This profile of PCB congeners closely matched profiles seen in penguin eggs or penguin blood.

To investigate the impacts of synthetic lubricants on Antarctic infaunal communities, a field experiment was setup near Australia's Casey Station, East Antarctica. Two types of synthetic lubricants were tested: an ‘Unused’ and ‘Used’ conventional synthetic lubricant, and an alternative marketed as ‘biodegradable’. Clean defaunated sediment was contaminated with the lubricants, decanted into trays, and deployed by divers onto the seabed in a randomised block design. Sediments were sampled 5 and 56 weeks after deployment. After 5 weeks, benthic assemblages that had recruited to the lubricant contaminated sediments were significantly different to those in ‘Control’ sediments, and differences were more pronounced after 56 weeks. Total number of individuals did not significantly differ between treatments after 5 weeks. However, after 56 weeks total individuals in the ‘Control’ sediments were significantly greater than in the contaminated sediments. Nototanais antarcticus (tanaid) and to a lesser extent Monoculodes sp. (gammarid), Tanaid sp. IV and Eudorella sp. (cumacean) had significantly higher abundances in the control sediments after 56 weeks compared to the contaminated sediments. Copepods numerically dominated the benthic assemblages at both sampling times; however, their abundance did not significantly differ across treatments. The community recruiting to the contaminated sediments remained different from that in the ‘Control’ sediments for the duration of the experiment (1 year). The ‘biodegradable’ lubricant was just as environmentally harmful to the Antarctic infauna as the ‘conventional’ lubricant currently used at Australia's Antarctic stations. Our results demonstrate that changes to recruitment are one of the potential environmental consequences of a lubricant spill to Antarctic benthic communities, and reinforce the importance of preventative oil spill management and effective clean-up procedures. Further monitoring of this field experiment will provide much needed information about the long-term impacts by synthetic lubricants in the Antarctic marine environment.

The Antarctic Treaty permits the discharge of wastewater into Antarctic marine waters providing that conditions exist for initial dilution and rapid dispersal. We investigated the dilution and dispersal of macerated wastewater around Australia's Davis Station in East Antarctica and examined sediments for evidence of contaminants. Methods used to examine hydrodynamic conditions included current meters, dye release experiments and measurement of sewage-associated microbial markers and surfactants in the water column. We measured marine sediments for metals, nutrients, PBDEs, hydrocarbons and faecal sterols. We propose that if there is adequate dilution and dispersal there would be no significant difference in contaminant concentrations in sediments around the outfall compared to distant control sites. Currents were strongly correlated with prevailing wind conditions. Modelling indicated that diffusivity of wastewater had the greatest effect on dilution factors and that neither discharge rates nor local currents had as much effect. During summer conditions of open water, wastewater is likely to be constrained in a narrow plume close to the coast. Concentrations of sewage bacteria were high around the outfall and detected up to 1.5 km away, along with dye. There were significant differences in sediment concentrations of metals, PBDEs, hydrocarbons, nutrients and faecal sterols between sites within 2 km of the outfall and control sites. We conclude that dilution and dispersal conditions at the Davis outfall are insufficient to prevent the accumulation of contaminants in local sediments and that microbial hazards posed by wastewater are an environmental risk to local wildlife.

The Arctic and Antarctic polar regions are subject to multiple environmental threats, arising from both local and ex-situ human activities. We review the major threats to polar ecosystems including the principal stressor, climate change, which interacts with and exacerbates other threats such as pollution, fisheries overexploitation, and the establishment and spread of invasive species. Given the lack of progress in reducing global atmospheric greenhouse-gas emissions, we suggest that managing the threats that interact synergistically with climate change, and that are potentially more tractable, is all the more important in the short to medium term for polar conservation. We show how evidence-based lessons learned from scientific research can be shared between the poles on topics such as contaminant mitigation, biosecurity protocols to reduce species invasions, and the regulation of fisheries and marine environments. Applying these trans-polar lessons in tandem with expansion of international cooperation could substantially improve environmental management in both the Arctic and Antarctic.

Antarctic macroalgae survive extended periods of darkness followed by rapid and extreme increases in irradiance when sea-ice breaks out in summer. Algae from dark, ice-covered locations had low values of saturating irradiance (Ek: 4–19 µmol photons m−2 s−1), low relative rates of electron transport (rETRmax: 2.0–3.6 µmol electrons m−2 s−1) and high values of effective quantum yield (ΔF/ : 0.52–0.70). Algae from brighter open-water locations had high Ek (13–67), high rETRmax (3.1–22.9) and lower ΔF/ (0.28–0.50). Overall values of ΔF/ and maximum quantum yield (Fv/Fm) were generally higher for ice-covered algae. Photosynthetic pigment, C : N and δ13C varied little with irradiance. Diel photosynthetic changes were measured in situ using a custom-built, multi-channel fluorometer. Under sea-ice, ΔF/ of Iridaea mawsonii increased significantly from 0.54 at midday (∼4 µmol photons m−2 s−1) to 0.64 at midnight, despite the relatively low midday irradiance. ΔF/ of ice-free macroalgae also varied significantly over...

Abandoned work sites, disposal sites, hazardous waste and untreated fuel spills in Antarctica have recently begun to receive significant attention. A profile of the clean-up at Casey waste disposal site demonstrates a suite of cultural, social, economic and scientific changes to the way Antarctica and its environmental management are viewed.

In many temperate regions, fuel and oil spills are sometimes managed simply by allowing natural degradation to occur, while monitoring soils and groundwater to ensure that there is no off-site migration or on-site impact. To critically assess whether this approach is suitable for coastal Antarctic sites, we investigated the extent of evaporation and biodegradation at three old fuel spills at Casey Station. Where the contaminants migrated across frozen ground, probably beneath snow, approximately half the fuel evaporated in the first few months prior to infiltration at the beginning of summer. Once in the ground, however, evaporation rates were negligible. In contrast, minor spills from fuel drums buried in an abandoned waste disposal site did not evaporate to the same extent. Biodegradation within all three spill sites is generally very minor. We conclude that natural attenuation is not a suitable management strategy for fuel-contaminated soils in Antarctic coastal regions.

A field experiment investigating the effect of oil contamination on benthic microbial communities was conducted near Casey Station, East Antarctica. Defaunated sediment was treated with a mixture of Special Antarctic Blend diesel and lubricating oil and deployed in three different bays for eleven weeks. A molecular fingerprinting technique, denaturing gradient gel electrophoresis (DGGE), was used to investigate the microbial community structure. The variation between replicate samples within treatment groups indicates that the benthic microbial populations are very diverse and evenly distributed. Comparisons to determine the significance of both deployment location and hydrocarbon treatment showed that the greatest effect was from a combination of location and treatment. Detailed analysis suggests that subtle differences may be obscured by variability introduced by PCR and gel stages in DGGE, undermining this experimental approach. It is concluded that both location and hydrocarbon contamination influenced the development of the microbial communities but that the effect of hydrocarbon treatment varied with location. This has important implications for the design of future experiments on the effect of hydrocarbons on benthic communities, especially if it is intended to generalize the conclusions drawn from site specific studies. © Antarctic Science Ltd.

The effects of diesel fuel and three lubricating oils on microbial communities in marine sediment were investigated in a field experiment at Casey Station, Antarctica. Sediment from a pristine site in Antarctica was treated with either Special Antarctic Blend (SAB) diesel, a synthetic lubricant (Mobil 0W-40), the same lubricant after use in a vehicle or an equivalent unused biodegradable lubricant (Titan GT1). The sediment was re-deployed in trays on the seabed for 5 weeks during the austral summer. The microbial community structure in the sediment upon collection, deployment and retrieval was investigated using denaturing gradient gel electrophoresis (DGGE), most probable number (MPN) counts and direct microscopic counting. It was found that only minor changes occurred in the microbial communities due to the experimental protocol. After 5 weeks however, there were significant differences between the communities in the SAB and clean and used lubricant (Mobil 0W-40) as compared to the control treatment. There was no significant difference between the control and biodegradable oil (Titan GT1) treatment. These results indicate that SAB and synthetic lubricants have a measurable effect on sediment microbial communities in the short-term. The biodegradable oil did not produce such an effect and we conclude that the use of such an oil could reduce the risks associated with oil spills in the Antarctic environment.

The introduction of invasive species may be the most profound modern threat to biological communities in high-latitude regions. In the Southern Ocean, the natural transport mechanism for shallow-water marine organisms provided by kelp rafts is being increasingly augmented by plastic debris and shipping activity. Plastic debris provide additional opportunities for dispersal of invasive organisms, but dispersal routes are passive, dependent on ocean currents, and already established. In contrast, ships create novel pathways, moving across currents and often visiting many locations over short periods of time. Transportation of hull-fouling communities by vessel traffic thus poses the most likely mechanism by which exotic species may be introduced to the Southern Ocean.

Prior to environmental legislation in the 1980s, anthropogenic waste in Antarctica was often deposited into landfill sites or into the sea. This resulted in metal contamination in terrestrial and near-shore marine environments. In this study, we assess the feasibility of using both past and present diatom assemblages to reconstruct and monitor past and future metal contamination. Our dataset included the analyses of both surface sediment samples and sediment cores from a contaminated site near Casey Station, Antarctica. Redundancy analyses indicated a strong relationship between metal concentrations and the composition of diatom communities. Within the surface sediment samples, tin and lead individually explained 43% of the variation observed in the diatom data; copper and iron explained 42% of this variation. In the sediment cores, tin and lead individually explained 53% of the variation in diatom community composition. In the same samples copper explained 47% of this variation, with iron explaining 46% of the observed variation. Once one metal had been selected, incorporating further metal data into the analyses added little extra information. Modern analog technique (MAT) analyses showed a strong correlation between actual and predicted values within one dataset (R2: Cu 0.75; Pb 0.86; Sn 0.89; p

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A series of in situ and aquarium experiments were conducted in the vicinity of the Bailey Peninsula area (Casey Station, East Antarctica) to investigate the bioturbation behaviour of the Antarctic spatangoid urchin Abatus ingens (Koehler 1928). Rates of sediment transport by A. ingens were estimated from measurements of locomotion rates, sediment reworking depth and feeding rates. A. ingens bioturbates and feeds on the surface sediment (top 1 to 2 cm) by pushing diatom communities and sediment ahead and to the side of its track, thus increasing vertical and horizontal sediment transport. Over a 24 h period in situ, A. ingens spends prolonged periods of time stationary (16.7 h) and only short periods of time in locomotion (7.3 h). In the aquarium, however, A. ingens was observed to spend half of the time moving and the other half stationary. Locomotion rate measured in the aquarium was faster (1.95 cm h -1 [1.20 SD]) than in situ (0.30 cm h -1 [0.27 SD]). In addition, A. ingens moves significantly faster during light hours than periods of darkness in situ. An ingestion rate of 0.02 to 0.06 g h -1 of dry sediment was measured for A. ingens, with a gut sediment passage time of 72 to 97 h. A. ingens reworks 2.76 cm 3 h -1 (2.52 SD) in situ; however, this calculation (based on forward movement only) may be an underestimate because A. ingens still reworks the sediment (via rocking and rotating on the spot) when it is not moving forwards. It is concluded that A. ingens is a significant contributor to the reworking of sediments in the Antarctic benthic environment.

A regional survey of potential contaminants in marine or estuarine sediments is often one of the first steps in a post-disturbance environmental impact assessment. Of the many different chemical extraction or digestion procedures that have been proposed to quantify metal contamination, partial acid extractions are probably the best overall compromise between selectivity, sensitivity, precision, cost and expediency. The extent to which measured metal concentrations relate to the anthropogenic fraction that is bioavailable is contentious, but is one of the desired outcomes of an assessment or prediction of biological impact. As part of a regional survey of metal contamination associated with Australia's past waste management activities in Antarctica, we wanted to identify an acid type and extraction protocol that would allow a reasonable definition of the anthropogenic bioavailable fraction for a large number of samples. From a kinetic study of the 1 M HCl extraction of two Certified Reference Materials (MESS-2 and PACS-2) and two Antarctic marine sediments, we concluded that a 4 h extraction time allows the equilibrium dissolution of relatively labile metal contaminants, but does not favour the extraction of natural geogenic metals. In a regional survey of 88 marine samples from the Casey Station area of East Antarctica, the 4 h extraction procedure correlated best with biological data, and most clearly identified those sediments thought to be contaminated by runoff from abandoned waste disposal sites. Most importantly the 4 h extraction provided better definition of the low to moderately contaminated locations by picking up small differences in anthropogenic metal concentrations. For the purposes of inter-regional comparison, we recommend a 4 h 1 M HCl acid extraction as a standard method for assessing metal contamination in Antarctica.

Abandoned waste dumps in Antarctica pose an environmental hazard due to contami- nant mobilisation in marine and terrestrial habitats. At Casey Station, east Antarctica, a shoreline waste dump has contaminated adjacent marine sediments with metals, hydrocarbons and organic carbon. This study experimentally assessed a model whereby contamination of marine sediment can lead to changes in recruitment and differences in soft-sediment assemblages. We tested the hypoth- eses that recruitment would be different at disturbed 'station' locations compared to controls and dif- ferent in contaminated sediment compared to control sediment. We conducted 2 reciprocal sediment- transplant field experiments over 2 consecutive years in which defaunated sediments were deployed at disturbed locations and control locations and were recovered after 9 mo (March to November: win- ter), and also after 12 mo. The majority of fauna recruiting to the experiment were highly motile spe- cies with non-pelagic lecithotrophic larvae, such as gammarids, tanaids, isopods and gastropods. There were large differences in recruiting assemblages between all locations and there were signif- icant differences in recruitment between disturbed and control locations. Assemblages in contami- nated sediment were significantly different from those in control sediment. Differences in abun- dances of individual taxa between control and contaminated sediment were complex and difficult to interpret. Assemblages recruiting to the control locations were more variable than those recruiting to disturbed locations. This study provides evidence that contaminants in marine sediments adjacent to the waste dump at Casey Station may be having an environmental impact.

Streamlined subglacial sediments are common in seafloor bathymetric images from many glaciated margins. Less common are seafloor features left by cold-based ice. The shallow waters around the now largely ice-free Vestfold Hills in East Antarctica (Fig. 1a, e) show few streamlined sedimentary features, even though the area has clearly been glaciated as implied by striated bedrock, moraine ridges and abundant erratic boulders on adjacent exposed land. A likely explanation for the absence of streamlined subglacial landforms is that the area was glaciated by ice frozen to its bed. Fig. 1. Multibeam swath bathymetry, outcrop photo and topographic profiles of boulder-rich debris mantle and sand ribbons from the Vestfold Hills coastal zone, East Antarctica. ( a ) Sun-illuminated bathymetric image of Airport Beach Embayment showing the debris mantle. Ice-keel ploughmarks are shown outside the embayment. Acquisition system Kongsberg EM3002. Frequency 300 kHz. Grid-cell size 2 m. ( b ) Close-up of debris mantle showing individual boulders. ( c ) Photograph of bouldery debris mantle above sea level. Large boulder is 4 m in diameter. ( d ) Multibeam image of sand ribbons and boulders. ( e ) Location of study area (red …

The ways by which contaminants in freezing ground disperse and interact with associated ecosystems is a new and challenging field of applied research that is crucial to effective assessment, monitoring, and remediation in cold regions. Three key issues have been identified as needing urgent research and development. The first concerns the development and application of meaningful environmental guidelines for cold regions. This usually means that contaminants in freezing ground per se need to be considered in their broadest context by also addressing associated ecosystems, such as the receiving marine environment. The second issue concerns developing best practice for bioremediation of seasonally frozen soils. Of particular concern are the risks, benefits, and costs of using so-called bioproducts, which may not offer substantial improvements over biostimulation of indigenous cold-adapted organisms. The third issue concerns the need for assessment and monitoring protocols and cost-effective analytical tools. In this respect the potential use of field portable instruments deserves careful consideration and on-site testing. Taken together, development of these issues during the coming years will be crucial if the science behind managing contaminants in freezing ground is to catch up with the knowledge that underpins the remediation industry elsewhere.

The Larsemann Hills provide a unique opportunity for studying the environmental impacts of four research facilities run by three nations (Australia, China, and Russia). Soil and water samples collected from the vicinity of each station approximately 10 years after their establishment were analysed for a variety of hydrocarbons, metals, and nutrients. Results confirm that hydrocarbon contamination is the most common impact of the stations. Nutrient enrichment of soil was identified within small areas of each station, and water samples obtained from several local tarns and meltpools revealed low-level contamination by metals and polyaromatic hydrocarbons (PAH). Faecal coliforms were present in intertidal pools adjacent to sewage effluent discharge but not in any other water bodies tested. The cumulative impact of the four facilities was an increase in the number of sites contaminated, rather than increased contamination at specific locations due to the additive effect of overlapping sources. The highest levels of contamination were extremely localised and the footprint of contamination arising from each of the facilities remained discrete from that of neighbouring stations. These data provide a baseline to compare environmental conditions at these locations in the Larsemann Hills before and after implementation of the Protocol on Environmental Protection to the Antarctic Treaty.

Contaminants, in freezing ground or elsewhere in the world, are of concern not simply because of their presence but because of their potential for detrimental effects on human health, the biota, or other valued aspects of the environment. Understanding these effects is central to any attempt to manage or remediate contaminated land. The polar regions are different from other parts of the world, and it would be naïve to assume that the mass of information developed in temperate regions can be applied without modification to the polar regions. Despite their obvious environmental similarities, there are important differences between the Arctic and Antarctic. The landmass of the Arctic is much warmer than that of the Antarctic and as a result has a much greater diversity and abundance of flora. Because of its proximity to industrial areas in the Northern Hemisphere, the Arctic also experiences a higher input of contaminants via long-range aerial transport. In addition, the Arctic, with its indigenous population and generally undisputed territorial claims, has long been the subject of resource utilisation, including harvesting of living resources, mineral extraction, and the construction of military infrastructure. The history of human activity in Antarctica is relatively brief, but in this time there has been a series of quite distinct phases, culminating in the Antarctic now holding a unique position in the world. Activities in the Antarctic are governed by the Antarctic Treaty, which contains provisions dealing with environmental matters. The differences between the polar regions and the rest of the world, and between the Arctic and the Antarctic, significantly affect scientific and engineering approaches to the remediation of contamination in polar regions. This paper compares and contrasts the Arctic and Antarctic with respect to geography, configuration, habitation, logistics, environmental guidelines, regulations, and remediation protocols. Chemical contamination is also discussed in terms of its origin and major concerns and interests, particularly with reference to current remediation activities and site-restoration methodology.

Differences between marine soft-sediment assemblages at disturbed (two waste dumps, a sewage outfall and a wharf) and control locations were found at Casey Station, Antarctica. These differences were significant against considerable background spatial variability. Core samples were collected by divers using a hierarchical, spatially nested sampling design incorporating four scales: (i) locations (thousands of metres apart); (ii) sites (hundreds of metres apart); (iii) plots (tens of metres apart); and (iv) among replicates within plots (approximately 1 metre apart). Control locations had greater species richness and diversity than disturbed locations and there were many taxa found at control locations that were not recorded at disturbed locations. Assemblages at disturbed locations were less variable than those at control locations. In contrast, populations of some dominant species were more variable at disturbed locations than at control locations. Significant variation in populations of individual taxa was also found at all scales and although greatest at the level of location, variation was also large at the smallest scale, between replicate cores, indicating significant small-scale patchiness in populations of taxa. Patterns of assemblage structure were similar at fine (77 taxa) and medium (aggregated to 33 taxa) levels of taxonomic resolution, but changed at coarse levels of resolution (nine phyla). Soft-sediment assemblages at Casey Station are markedly different from those reported from other areas of Antarctica. Assemblages at Casey are almost completely dominated by crustaceans (up to 99% total abundance) and polychaetes are rare or in very low abundances in most areas investigated in the region. This is also the first demonstration that small Antarctic research stations (population 20-50 people) may cause impacts that are detectable in the adjacent marine environment.

The effects of metals and petroleum hydrocarbons on benthic marine diatom communities were assessed using a manipulative field experiment at Casey Station, Antarctica. Uncontaminated, metal contaminated, and petroleum hydrocarbon contaminated sediments were deployed for 11 weeks during the 1999 austral summer. The treatments were deployed at three different locations: Brown Bay, which has elevated levels of anthropogenic contaminants, and two uncontaminated reference locations, O'Brien Bay and Sparkes Bay, the latter of which has naturally occurring high concentrations of some heavy metals. At each location, significant differences between the composition of diatom communities recruiting to control and petroleum hydrocarbon contaminated treatments were observed. Navicula directa (Smith) Ralfs occurred at lower abundances in the petroleum hydrocarbon contaminated treatments than in the control treatments. In contrast, Navicula cancellata Donkin occurred at higher relative abundances in both contaminated treatments relative to the control treatment. Interactions between treatment and location were also observed for several species, including Navicula glaciei Van Heurck. Significant differences in the overall community composition of diatom communities between control and metal contaminated treatments and metal contaminated and petroleum hydrocarbon contaminated treatments were only observed within Brown Bay. The location of deployment also had a significant influence on the composition of diatom communities. Brown Bay had higher abundances of Achnanthes brevipes Agardh but lower abundances of Navicula aff. cincta (Ehrenberg) Van Heurck than either reference locations. This experiment demonstrated that benthic diatom communities are sensitive to sediment contamination and would be suitable for future monitoring work within this and other areas of Antarctica.

Correlations between the spatial distribution of soft-sediment assemblages and environmental variables were evaluated at a number of control and potentially impacted locations (waste dumps, a sewage outfall and a wharf) at Casey Station, East Antarctica. Patterns of assemblage composition were compared with patterns of environmental variables using univariate and multivariate techniques. The utility of these methods, however, is uncertain in areas of significant habitat heterogeneity (at scales

This study investigated the potential for transport of organisms between Hobart, Macquarie Island and the Antarctic continent by ships used in support of Antarctic science and tourism. Northward transport of plankton in ballast water is more likely than southward transport because ballast is normally loaded in the Antarctic and unloaded at the home port. Culturing of ballast water samples revealed that high-latitude hitchhikers were able to reach greater diversities when cultured at temperate thermal conditions than at typical Southern Ocean temperatures, suggesting the potential for establishment in the Tasmanian coastal environment. Several known invasive species were identified among fouling communities on the hulls of vessels that travel between Hobart and the Southern Ocean. Southward transport of hull fouling species is more likely than northward transport due to the accumulation of assemblages during the winter period spent in the home port of Hobart. This study does not prove that non-indigenous marine species have, or will be, transported and established as a consequence of Antarctic shipping but illustrates that the potential exists. Awareness of the potential risk and simple changes to operating procedures may reduce the chance of introductions in the future.

A manipulative field experiment was conducted at Casey Station, Antarctica, to determine the effect of contamination of marine sediments on the recruitment and development of soft-sediment assemblages. Uncontaminated marine sediments were defaunated and then contaminated by adding hydrocarbons (diesel fuel and lubrication oil) or heavy metals (extracted from contaminated soil) prior to deployment on the seabed for a period of eleven weeks during an Antarctic summer (December to February) at three locations. Two of the locations were intended as reference locations (O'Brien and Sparkes Bay) and were well away from the influence of station activities, but Sparkes Bay was found to be naturally contaminated by some metals. The other location (Brown Bay) was adjacent to an abandoned waste disposal site and is contaminated by hydrocarbons and metals, and soft-sediment assemblages are different from those in control locations. Recruiting assemblages were significantly different between locations and there was a significant effect of sediment contamination. Assemblages in hydrocarbon contaminated sediment were significantly different to those in control and metal treated sediment at two of the locations (Brown and Sparkes Bay). There were no differences between assemblages in control sediment and metal-contaminated sediment. Univariate analyses (ANOVAs) indicated greater abundances of crustaceans, mainly due to several species of gammarid, in control and metal treatments than hydrocarbon-treated sediment. Further analysis (t-tests) revealed additional differences between hydrocarbon vs. both control and metal treatments, in the total abundance, and abundance of gammarids, tanaids, ostracods, isopods and copepods, particularly at Brown Bay and Sparkes Bay. There was also a trend of greater abundances of polychaetes and gastropods in hydrocarbon and metal treatments compared to the control. In comparison with the hydrocarbon treatment, the metal treatment had little effect. There was significant spatial variability in recruitment within each location, which may have obscured some effects of sediment contamination. There were also significant differences in variability of recruitment between locations. The rate of fauna recruiting to sediments in this experiment at Casey were greater than previously recorded in Antarctica.