Antarctica has been subject to widespread, long-term and on-going human activity since the establishment of permanent research stations became common in the 1950s. Equipment may become intentionally or inadvertently lost in Antarctic marine and terrestrial environments as a result of scientific research and associated support activities, but this has been poorly quantified to date. Here we report the quantity and nature of equipment lost by the UK's national operator in Antarctica, the British Antarctic Survey (BAS). Over the 15-year study period (2005-2019), 125 incidents of loss were reported, with c. 23 tonnes of equipment lost of which 18% by mass was considered hazardous. The geographical distribution of lost equipment was widespread across the BAS operational footprint. However, impacts are considered low compared to those associated with research station infrastructure establishment and operation. To reduce environmental impact overall, we recommend that, where possible, better use is made of existing research station capacity to facilitate field research, thereby reducing the need for construction of new infrastructure and the generation of associated impacts. Furthermore, to facilitate reporting on the state of the Antarctic environment, we recommend that national Antarctic programmes reinvigorate efforts to comply with Antarctic Treaty System requirements to actively record the locations of past activities and make available details of lost equipment. In a wider context, analogous reporting is also encouraged in other pristine areas subject to new research activities, including in other remote Earth environments and on extra-terrestrial bodies.

The importance of cold-water blue carbon as biological carbon pumps that sequester carbon into ocean sediments is now being realised. Most polar blue carbon research to date has focussed on deep water, yet the highest productivity is in the shallows. This study measured the functional biodiversity and carbon standing stock accumulated by shallow-water (<25 m) benthic assemblages on both hard and soft substrata on the Antarctic Peninsula (WAP, 67° S). Soft substrata benthic assemblages (391 ± 499 t C km−2) contained 60% less carbon than hard substrata benthic assemblages (648 ± 909). In situ observations of substrata by SCUBA divers provided estimates of 59% hard (4700 km) and 12% soft (960 km) substrata on seasonally ice-free shores of the Antarctic Peninsula, giving an estimate of 253,000 t C at 20 m depth, with a sequestration potential of ~4500 t C year−1. Currently, 54% of the shoreline is permanently ice covered and so climate-mediated ice loss along the Peninsula is predicted to more than double this carbon sink. The steep fjordic shorelines make these assemblages a globally important pathway to sequestration, acting as one of the few negative (mitigating) feedbacks to climate change. The proposed WAP marine protected area could safeguard this ecosystem service, helping to tackle the climate and biodiversity crises.

Ocean mixing around Antarctica exerts key influences on glacier dynamics and ice shelf retreats, sea ice, and marine productivity, thus affecting global sea level and climate. The conventional paradigm is that this is dominated by winds, tides, and buoyancy forcing. Direct observations from the Antarctic Peninsula demonstrate that glacier calving triggers internal tsunamis, the breaking of which drives vigorous mixing. Being widespread and frequent, these internal tsunamis are at least comparable to winds, and much more important than tides, in driving regional shelf mixing. They are likely relevant everywhere that marine-terminating glaciers calve, including Greenland and across the Arctic. Calving frequency may change with higher ocean temperatures, suggesting possible shifts to internal tsunamigenesis and mixing in a warming climate.

Giant icebergs can greatly impact the mass, freshwater and nutrient budgets of the ocean. They can deposit large amounts of freshwater at great distances from their origins, impacting upper-ocean stratification and mixing, and they can be important vectors for micronutrient delivery with impacts on primary production and carbon drawdown. Their impacts on advection, productivity and blocking of flows can be critical for zooplankton and regional ecosystem functioning, with consequences for higher trophic levels and local fisheries. Their breakouts from ice shelves create new opportunities for biological colonisation and carbon sinks and their collisions with the seabed (iceberg scour) can shape local and regional benthic biodiversity patterns and influence carbon sequestration. In 2017, the A68 iceberg (around 6000 km2) calved from the Larsen C Ice Shelf on the Antarctic Peninsula. It subsequently moved eastward and northward, crossing the Scotia Sea to move, virtually intact, to within 300 km of the island of South Georgia (SG) in late 2020. This caused concern, following the impact of a previous iceberg, A38, on the SG ecosystem in 2003-2004. Further, given the advances in observing technology since the time of the previous iceberg, it afforded an unparalleled opportunity to study in detail the impacts of giant bergs on the ocean physical, biogeochemical and biological systems. Diverse datasets were collected in response to this event. A research cruise on RRS James Cook was mobilised, to study the iceberg as it approached SG and fragmented into multiple smaller pieces. These measurements included physical parameters (including oxygen isotopes to inform on freshwater sources), dissolved inorganic nutrients, biosilica concentration, and composition of the phytoplankton community to inform bloom dynamics and primary production by the input of terrigenous material. Ocean gliders, deployed from the ship, surveyed the largest iceberg fragment in extremely close proximity and followed this for the remainder of its life, deconvolving the iceberg influence from frontal dynamics and assisting in understanding meltwater influence. Concurrently, Earth Observation (EO) techniques were employed including Sentinel-1 SAR imagery, Planet Labs very high-resolution optical imagery, MODIS Aqua and Terra imagery and satellite radar and laser altimetry. A sediment trap deployed on a mooring downstream of SG will be utilised to investigate the carbon export from the cruise period to that of the previous 10 years while enhanced observations on higher predator colonies will compare their foraging paths and breeding performance to those of previous years. This presentation will discuss preliminary findings from the study of A68, including EO-derived quantifications of changing iceberg morphology, ice loss from fragmentation and basal melting, and the significance of fractures in dictating collapse fissures. Physical oceanographic data from the ship and gliders are used to determine the impact on water column stability, mixing and circulation on a range of scales. Biogeochemical and biological data reveal the impact of interacting processes on phytoplankton community biomass and species composition. Ecosystem implications and future directions of investigation will be outlined.

The boreal copepod Calanus finmarchicus sequesters substantial amounts of carbon (C) in the deep layers of the North Atlantic Ocean through their contribution to the “lipid pump.” This pump is driven by these zooplankton descending from the surface layers to spend prolonged periods at depth during which time they metabolise substantial lipid reserves and a fraction suffer mortality. C. finmarchicus is principally a boreal species but is expatriated by currents flowing northwards into Arctic regions such as the Fram Strait, where it is now able to complete its life cycle. We considered how this expansion to its distributional range adds to the estimated magnitude of the lipid pump. Field sampling in the Fram Strait found C. finmarchicus abundance to be spatially variable with high values, equivalent to those reported for core distributional areas further south, found mainly in the eastern region. Lipid reserve levels were sufficient for many individuals to survive the overwintering period and reproduce the following spring. In accordance with abundance patterns, lipid pump magnitude was greater in the Eastern Fram Strait (2.04 g C m−2 year−1) compared to the Western Fram Strait (0.33 g C m−2 year−1). At least for the eastern region, these rates are similar to those reported for this species elsewhere (average of 4.35 g C m−2 year−1). When extrapolated to the wider spatial area of the Fram Strait, the lipid pump generated by this species in this ocean sector amounts to 0.3 Mt C year−1. Although constituting a modest proportion of the total C. finmarchicus lipid pump of 19.3 Mt C year−1, it indicates that the continued northwards expansion of this species will act to increase the size of its lipid pump, which may counteract that lost through the northwards retreat of its Arctic congeners, Calanus glacialis and Calanus hyperboreus.

Abstract Antarctica’s Pole of Inaccessibility (Southern Pole of Inaccessibility (SPI)) is the point on the Antarctic continent farthest from its edge. Existing literature exhibits disagreement over its location. Using two revisions of the Scientific Committee on Antarctic Research’s Antarctic Digital Database, we calculate modern-day positions for the SPI around 10 years apart, based on the position of the “outer” Antarctic coastline, i.e. its boundary with the ocean. These show that the position of the SPI in the year 2010 was around 83° 54’ S, 64° 53’ E, shifting on the order of 1 km per year as a result of changes of a similar magnitude in the Amery, Ronne-Filchner and Ross Ice Shelves. Excepting a position of the SPI calculated by British Antarctic Survey in 2005, to which it is very close, our newly calculated position differs by 150–900 km from others reported in the literature. We also consider the “inner” SPI, defined by the coastline with floating ice removed. The position of this SPI in 2010 is estimated as 83°37’ S, 53° 43’ E, differing significantly from other reported positions. Earlier cartographic data are probably not sufficiently accurate to allow its rate of change to be calculated meaningfully.

Physiological comparisons are fundamental to quantitative assessments of the capacity of species to persist within their current distribution and to predict their rates of redistribution in response to climate change. Yet, the degree to which physiological traits are conserved through evolutionary history may fundamentally constrain the capacity for species to adapt and shift their geographic range. Taxa that straddle major climate transitions provide the opportunity to test the mechanisms underlying evolutionary constraints and how such constraints may influence range shift predictions. Here we focus on two abundant and shallow water nacellid limpets which have representative species on either side of the Polar front. We test the thermal thresholds of the Southern Patagonian limpet, Nacella deaurata and show that its optimal temperatures for growth (4 °C), activity (-1.2 to -0.2 °C) and survival (1 to 8 °C) are mismatched to its currently experienced annual sea surface temperature range (5.9 to 10 °C). Comparisons with the congeneric Antarctic limpet, N. concinna, reveal an evolutionary constraint on N. deaurata physiology, with overlapping thermal capacities, suggesting that a cold climate legacy has been maintained through the evolution of these species. These physiological assessments predict that the South American range of N. deaurata will likely decline with continued warming. It is, however, one of the first species with demonstrated physiological capacity to successfully colonize the cold Southern Ocean. With the expected increase in opportunities for transport within high southern latitudes, N. deaurata has the potential to establish and drive ecological change within the shallow Southern Ocean.

High-latitude ecosystems are among the fastest warming on the planet1. Polar species may be sensitive to warming and ice loss, but data are scarce and evidence is conflicting2–4. Here, we show that, within their main population centre in the southwest Atlantic sector, the distribution of Euphausia superba (hereafter, ‘krill’) has contracted southward over the past 90 years. Near their northern limit, numerical densities have declined sharply and the population has become more concentrated towards the Antarctic shelves. A concomitant increase in mean body length reflects reduced recruitment of juvenile krill. We found evidence for environmental controls on recruitment, including a reduced density of juveniles following positive anomalies of the Southern Annular Mode. Such anomalies are associated with warm, windy and cloudy weather and reduced sea ice, all of which may hinder egg production and the survival of larval krill5. However, the total post-larval density has declined less steeply than the density of recruits, suggesting that survival rates of older krill have increased. The changing distribution is already perturbing the krill-centred food web6 and may affect biogeochemical cycling7,8. Rapid climate change, with associated nonlinear adjustments in the roles of keystone species, poses challenges for the management of valuable polar ecosystems3. As the southwest Atlantic sector of the Southern Ocean has warmed, the distribution of a key species, Antarctic krill, has contracted southwards. This has occurred in tandem with a decline in recruitment of juveniles, linked to increasingly positive anomalies of the Southern Annular Mode.

Large-bodied animals such as baleen whales can now be detected with very high resolution (VHR) satellite imagery, allowing for scientific studies of whales in remote and inaccessible areas where traditional survey methods are limited or impractical. Here we present the first study of baleen whales using the WorldView-3 satellite, which has a maximum spatial resolution of 31cm in the panchromatic band, the highest currently available to nonmilitary professionals. We manually detected, described, and counted four different mysticete species: fin whales (Balaenoptera physalus) in the Ligurian Sea, humpback whales (Megaptera novaeangliae) off Hawaii, southern right whales (Eubalaena australis) off Peninsula Valdes, and gray whales (Eschrichtius robustus) in Laguna San Ignacio. Visual and spectral analyses were conducted for each species, their surrounding waters, and nonwhale objects (e.g., boats). We found that behavioral and morphological differences made some species more distinguishable than others. Fin and gray whales were the easiest to discern due to their contrasting body coloration with surrounding water, and their prone body position, which is proximal to the sea surface (i.e., body parallel to the sea surface). These results demonstrate the feasibility of using VHR satellite technology for monitoring the great whales.

Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Ocean food webs and krill are also fished commercially. Managing this fishery sustainably, against a backdrop of rapid regional climate change, requires information on distribution and time trends. Many data on the abundance of both taxa have been obtained from net sampling surveys since 1926, but much of this is stored in national archives, sometimes only in notebooks. In order to make these important data accessible we have collated available abundance data (numerical density, no. m(-2)) of postlarval E. superba and salp individual (multiple species, and whether singly or in chains). These were combined into a central database, KRILLBASE, together with environmental information, standardisation and metadata. The aim is to provide a temporal-spatial data resource to support a variety of research such as biogeochemistry, autecology, higher predator foraging and food web modelling in addition to fisheries management and conservation. Previous versions of KRILLBASE have led to a series of papers since 2004 which illustrate some of the potential uses of this database. With increasing numbers of requests for these data we here provide an updated version of KRILLBASE that contains data from 15 194 net hauls, including 12 758 with krill abundance data and 9726 with salp abundance data. These data were collected by 10 nations and span 56 seasons in two epochs (1926-1939 and 1976-2016). Here, we illustrate the seasonal, inter-annual, regional and depth coverage of sampling, and provide both circumpolar-and regional-scale distribution maps. Krill abundance data have been standardised to accommodate variation in sampling methods, and we have presented these as well as the raw data. Information is provided on how to screen, interpret and use KRILLBASE to reduce artefacts in interpretation, with contact points for the main data providers.