In this study, the researchers carried out a comprehensive review of trace elements in soils from Antarctica’s ice-free areas, examining concentrations in pristine zones and in areas influenced by human activity, with special emphasis on the impact of permafrost thaw on their mobilization. Antarctica was divided into six regions with similar climatic and environmental characteristics, allowing results to be compared, natural and anthropogenic sources of contaminants to be distinguished, and vulnerable areas requiring future monitoring to be identified.

The results showed that the active layer of permafrost controls the accumulation and mobility of trace elements in Antarctic soils and that permafrost thaw associated with climate change can remobilize previously retained contaminants, increasing their environmental availability.

Furthermore, concentrations of elements such as Hg, Pb, Cd, Cu, Cr, and Ni arise from both natural and anthropogenic sources. In the South Shetland Islands, particularly on King George Island, higher values are recorded near scientific stations, waste sites, fuel spills, and other human infrastructures, whereas on Deception Island, volcanic activity leads to naturally elevated concentrations of Hg and As, with permafrost potentially acting as a temporary reservoir for these elements (Fig. 1). Scientists also noted that glacier retreat, increasing active-layer thickness, and permafrost degradation are altering hydrological dynamics and contaminant transport.

The combined effects of human pressure and climate change pose a growing risk to terrestrial and coastal ecosystems, underscoring the need for continuous monitoring.

Source: Zilhão, H., Cesário, R., Vieira, G. & Canário, J. (2025). Trace elements in soils of the Antarctic ice-free areas: Insights on natural geochemical values, anthropogenic impact and possible remobilisation upon permafrost thaw. Earth-Science Reviews, 268.

Author: Diana Vaz

A team led by a Portuguese researcher recently studied the ground surface temperatures in Barton Peninsula (Antarctic Peninsula), where ice-free areas are scattered among rocky hills and snow patches. They installed 20 small temperature sensors called iButtons at different elevations, slopes, and near snow patches, recording ground temperatures every three hours for a full year. By analyzing this data, the team could uncover what controls the freezing and thawing of the ground.

So, what did they discover? Elevation turned out to be the main factor: the higher you go, the colder the ground gets, with mean annual temperatures dropping from just above freezing at low elevations to below -2°C at higher sites. Snow cover also plays a huge role, acting like a natural blanket: areas with longer-lasting snow had longer freezing seasons and slower warming. Even the shape of the land and how much sunlight hits it influenced the temperature.

The team identified seven daily ground temperature regimes: some frozen all day, some thawed, and some cycling between freezing and thawing. By combining this information, they classified the whole area into four main types of annual temperature regimes, ranging from long frost seasons near snow patches to short frost seasons with rapid warming at lower elevations. They even created a model that can map these patterns across the Peninsula with 90% accuracy.

Why does this matter? These findings show just how sensitive ground temperatures are to small changes in topography and snow cover. This matters not only for understanding permafrost and climate in Antarctica but also for predicting how these areas might respond to future warming. In other words, even tiny details in the landscape can have a huge impact on the frozen world beneath our feet!

Source: Baptista, J., Vieira, G., & Lee, H. (2024). Ground surface temperature regimes are controlled by the topography and snow cover in the ice-free areas of Maritime Antarctica. Catena, 240, 107947

However, since 1950, the Antarctic Peninsula has experienced a steady increase in air temperatures, which is already having a noticeable impact on permafrost dynamics.

In a new study led by a Portuguese researcher, scientists modelled the evolution of permafrost temperature and active layer thickness on King George Island, located in the Antarctic Peninsula. The aim was to understand how these variables have changed over time and to develop a methodology that could later be applied to other ice-free regions of the peninsula.

To achieve this, the team used the CryoGrid Community Model, fed with borehole data from the King Sejong Station (which provides ground temperature records at various depths) and ERA5 climate reanalysis data.

The results are clear: since 1950, permafrost temperatures have increased by about 2 °C, and the active layer has thickened from 1.6 to 3.5 metres. And the most concerning part? This warming has accelerated significantly since 2016.

But why is this important? Because permafrost degradation in Antarctica affects hydrological dynamics, controls the flow of sediments and contaminants, causes ground instability, and influences vegetation development — all of which have direct impacts on terrestrial ecosystems and biodiversity.

This study represents an important step toward a better understanding of how climate change is affecting Antarctica, and it helps us anticipate what might happen in the future to the planet’s frozen ground.

Source: Baptista, J. P., Vieira, G. B. G. T., Lee, H., Correia, A. M. D. C. S., & Westermann, S. (2025). Modelling the evolution of permafrost temperatures and active layer thickness in King George Island, Antarctica, since 1950. Frozen ground/Antarctic. https://doi.org/10.5194/egusphere-2025-150

Author: Diana Martins

The models indicate that increasing sea surface temperatures and retreating sea ice (key aspects of ocean warming) are major drivers of changing habitat conditions. Other factors, like chlorophyll concentration (a proxy for primary productivity), also play an important role.

The species-specific responses include potential winners and losers:

Potential Winners: Subtropical and cosmopolitan squid species (e.g., Histioteuthis atlantica, Teuthowenia pellucida, Todarodes filippovae, and Bathyteuthis abyssicola) may gain suitable habitat, particularly at higher latitudes (Figure 1).

Potential Losers: In contrast, Antarctic and many subantarctic species (such as Onykia ingens, Onykia robsoni, Martialia hyadesi, Gonatus antarcticus, Histioteuthis eltaninae, Slosarczykovia circumantarctica, Mesonychoteuthis hamiltoni, Alluroteuthis antarcticus, Galiteuthis glacialis, Psychroteuthis glacialis, and especially Moroteuthopsis longimana) are projected to lose a significant portion of their current habitat (Figure 2).

Additionally, the study found that the northern limits of squid distributions are expected to move southward over time, with a reduction in biodiversity hotspots, which may alter the structure of the pelagic ecosystem. Changes in squid distribution could have cascading effects throughout the Southern Ocean food web, impacting predators such as seabirds, seals, and cetaceans that rely on squid as a major food source.

The authors note uncertainties related to the resolution of environmental data, the lack of trophic interactions in the models, and limited sampling in remote areas. They suggest that future studies incorporate finer-scale data (including depth as a third dimension) and more comprehensive biological information to better inform conservation and marine spatial planning.

Overall, the paper provides essential projections for understanding potential shifts in marine biodiversity due to climate change and highlights the importance of considering these changes in conservation strategies for the Southern Ocean.

Source: Guerreiro, M., Santos, C. P., Borges, F., Santos, C., Xavier, J. C., & Rosa, R. (2025). Projecting future climate change impacts on the distribution of pelagic squid in the Southern Ocean. Marine Ecology Progress Series, 757

Author: Sara Santos

Despite their importance, scientists have only scratched the surface of understanding which microbes live in the Arctic and what they do. Why? Mostly because of methodology constrains, studies until now have relied on sequencing just small fragments of microbial DNA, making it difficult to identify many species accurately.

This’s where this study comes in. Scientists wanted to test if there were differences between sequencing the full-length 16S rRNA gene and just sequencing short regions of the gene. Also, teste the influence of databases, comparing the commonly used SILVA databased to the more recent Genome Taxonomy Database (GTDB). Researchers thought that sequencing the entire gene and using GTDB for taxonomic assignment would recover a much more complete and accurate view at Arctic microbial communities.

The results? Indeed, using the two tools combined, the researchers were able to identify many more microbial species (Figure 1). Not only did they confirm the presence of known groups, but they also discovered new lineages and better classified many species that had previously been hard to identify to such taxonomic detail.

Why is this important? As the Arctic warms faster than any other region on Earth, understanding how its ecosystems work is more urgent than ever. Microbes are incredibly sensitive to changes in temperature and nutrients and if they change, the effetc can ripple through the entire ecosystem. So, by knowing who these microbes are and how they function, scientists can better monitor/predict how the Arctic is/will respond to climate change.

This study gives us a clearer way to investigate the hidden life of the Arctic Ocean. By using full-length gene sequencing and modern classification tools, researchers identified more species, painting a more detailed picture of Arctic microbial life.

Source: Pascoal, F., Duarte, P., Assmy, P. et al. Full-length 16S rRNA gene sequencing combined with adequate database selection improves the description of Arctic marine prokaryotic communities. Ann Microbiol 74, 29 (2024). https://doi.org/10.1186/s13213-024-01767-6

Author: Lucas Bastos

The researchers used stable isotope analyses (δ¹³C and δ¹⁵N) from the muscle tissues of various species collected during fishing seasons in 2020, 2021, and 2022. They identified a food-web with five main trophic levels, with Patagonian (Dissostichus eleginoides) and Antarctic (D. mawsoni) toothfishes as the top predators and noted a potential sixth level when including predators such as seals and whales (Figure 1).

The study found that food chain length varied between years, with the longest chain recorded in 2020 and a shortening of about 0.30 trophic levels by 2022. These changes were linked to shifts in the isotopic signatures of species across multiple trophic levels, suggesting that even mid-trophic level organisms showed significant variability over time.

A major finding is the strong positive linear relationship between food chain length and net primary production. Years with higher net primary production (and related parameters like chlorophyll a concentration) were associated with longer food chains. This supports the productivity hypothesis, which suggests that more productive systems can support a longer chain of energy transfer through more trophic levels. The research highlights the importance of interactions between pelagic (open water) and benthic/demersal (seafloor) components. This coupling occurs primarily between the third and fourth trophic levels, where mobile pelagic species (like squids and crustaceans) interact with demersal fish. Such coupling is key for energy and nutrient fluxes between different ecosystem compartments.

The authors suggest that as climate change increases productivity in the Southern Ocean, food webs may become longer. This has important implications for energy transfer efficiency, exposure to contaminants (due to biomagnification), and alterations in nutrient cycling, potentially affecting the entire ecosystem’s structure and function.

Overall, the paper demonstrates that deep‐sea food-web structure at the South Sandwich Islands is dynamic and strongly influenced by variations in net primary production. These findings provide crucial insights into how climate-driven changes in productivity could reshape trophic interactions and energy flow in one of the world’s most remote marine ecosystems.

Source: Queirós, J. P., Hollyman, P. R., Bustamante, P., Vaz, D., Belchier, M., & Xavier, J. C. (2025). Deep‐sea food‐web structure at South Sandwich Islands (Southern Ocean): net primary production as a main driver for interannual changes. Ecography.

Author: Sara Santos

But how did they do it? In this study, the scientists turned to eastern rockhopper penguins (Eudyptes chrysocome filholi), from Campbell Island (a sub-Antarctic island of New Zealand) as a biosampler. Researchers collected cephalopods’ beaks from their diet from two breeding seasons (1986–87 and 2012–13) in which they performed stable isotope analysis (SIA), forms of chemical elements that do not undergo radioactive decay. Using this method, they were able to examine the carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic signatures, which provide insights into the habitat and trophic level of organisms. δ¹³C values help to differentiate between inshore and offshore foraging habitats, while δ¹⁵N values indicate the organism’s position in the food web.

What did they find? Using the beaks, scientists were able to pinpoint the differences in cephalopod biodiversity in the diet of penguins between the two breeding seasons. The 1986-87 diet comprised seven cephalopod species while, contrastingly, the 2012-13 diet included only three species: Moroteuthopsis ingens, Nototodarus sloanii, and Octopus campbelli. Moreover, M. ingens and O. campbelli were present in both seasons, but N. sloanii was only found in the 2012-13 season. And what does this mean? Firstly, the overall diversity seemed to decrease, however, this is likely due to the smaller sample size (Nº1986-87= 69 vs Nº 2012-13= 11). Secondly, the identification of N. sloanii may indicate a southward habitat expansion, as this species is more common in the warmer waters of New Zealand.

What about the SIA? These revealed variations in habitat and trophic niches between species. Specifically, M. ingens showed no significant differences in δ¹³C or δ¹⁵N values between years (Figure 1), while for O. campbelli δ¹³C and δ¹⁵N values were significantly lower in 2012-13 compared to 1986-87 (Figure 2), suggesting a shift in foraging location and possibly a move to lower trophic levels. N. sloanii, presented δ¹³C values in accordance with the values of other sub‑Antarctic waters taxa and lower δ¹⁵N values indicative of foraging at lower trophic levels.

What does this mean? The differences in stable isotope values between seasons could be a sign of changes in oceanographic conditions such as warming waters, taking species to new habitats and feeding differently. Additionally, the presence of N. sloanii in diets offers insights into their foraging and possible interactions with New Zealand fisheries, which can affect both the fisheries and the conservation of the eastern rockhopper penguin.

Overall, this study contributes significantly to increasing the knowledge of cephalopod ecology in the Pacific sector of the Southern Ocean. It demonstrates that different cephalopod species exhibit distinct habitat preferences and trophic roles. The findings reinforce the importance of continued monitoring of cephalopod populations, particularly in the face of environmental changes that may alter their distribution and availability to predators like rockhopper penguins.

Source: Guímaro, H. R., Thompson, D. R., Morrison, K. W., Fragão, J., Matias, R. S., & Xavier, J. C. (2025). Evidence of eastern rockhopper penguin feeding on a key commercial arrow squid species. Polar Biology, 48(1), 1-7

Author: Lucas Bastos

The study measured stable isotope signatures and Hg concentrations in different species, including chinstrap penguins, skuas, gulls, southern giant petrels, and southern elephant seals. Significant differences in δ13C values among species were observed, with considerable overlap between seabird species and seals. Differences in δ15N values reflected variations in diet and trophic position. The lowest Hg concentrations were found in krill (0.007 ± 0.008 μg∙g–1) and the highest in southern giant petrels (12.090 ± 14.177 μg∙g–1).

Results showed a positive relationship between Hg concentrations and trophic levels, with Hg biomagnifying nearly twice at each trophic level. The study suggests that trophic interactions are the major pathways for Hg biomagnification in Southern Ocean ecosystems. The research also highlights that Hg concentrations may increase in marine organisms due to global warming, which enhances Hg methylation and its availability in low-oxygen waters. Long-lived, high trophic level predators, such as some seabirds and seals, are particularly vulnerable to the effects of Hg.

The study concludes that Hg biomagnification in the food webs of the Antarctic Peninsula results in high Hg burdens in top predators. As global temperatures rise, Hg concentrations are expected to increase, potentially causing significant negative effects on Antarctic organisms. The article emphasises the need for further studies to fully understand how taxonomic, geographic, and ecological differences influence Hg dynamics in the marine ecosystems of the Antarctic Peninsula.

Source: Matias, R. S., Guímaro, H. R., Bustamante, P., Seco, J., Chipev, N., Fragão, J., … & Xavier, J. C. (2022). Mercury biomagnification in an Antarctic food web of the Antarctic Peninsula. Environmental Pollution, 304, 119199.

DOI: 10.1016/j.envpol.2022.119199

Author: Laura Lopes

The study found significant changes in the habitat of four out of the five squid species, as indicated by shifts in δ¹³C values. This suggests that these species have changed their geographical distributions over time, likely in response to environmental changes. Taonius sp. B, Gonatus antarcticus, Galiteuthis glacialis, and Histioteuthis atlantica all showed changes in habitat, moving towards more northerly regions over the decades. Moroteuthopsis longimana (Figure 1) was the only species that maintained consistent habitat use, indicating a potentially greater tolerance to environmental changes.

Despite changes in habitat, the trophic levels of all five squid species, as concluded from δ¹⁵N values, remained relatively stable over the study period. This suggests that their roles within the food web have not shifted significantly, maintaining their importance as prey for top predators.

Of the five species, only Taonius sp. B showed a significant correlation between its isotope ratios and the environmental indices (SOI and SAM), indicating that these climatic factors directly influenced its trophic level and habitat.

In conclusion, the study suggests that while Southern Ocean squid have altered their habitat in response to changing environmental conditions, their trophic roles have remained stable. This adaptability could ensure their continued importance in the Southern Ocean ecosystem, even as climate change progresses. The findings highlight the potential resilience of these species to environmental variability and their critical role in the marine food web. This research provides valuable insights into the ecological responses of key nekton species in the Southern Ocean, which could be crucial for predicting future changes in the ecosystem under ongoing climate change.

Source: Abreu J, Phillips RA, Ceia FR, Ireland L, Paiva VH, Xavier JC (2020) Long-term changes in habitat and trophic level of Southern Ocean squid in relation to environmental conditions. Sci Rep

DOI: 10.1038/s41598-020-72103-6

Author: Sara Santos

The Arctic is part of the imaginary, social/collective and individual. This frozen region has unique characteristics that create an inhospitable place, remote and harsh in accessibility but where indigenous communities live. The imaginary of this region was created by the Greek navigator Pytheas, guided by the Great Bear Constellation(“Arktos”). Ensheathing European powers throughout centuries, mainly during the 19^th century, to reach this inhospitable location.

The concept “Polar Mediterranean” was introduced by Vilhjalmur Stefansson in the year 1920, after considering that the Arctic Ocean could be compared to the Mediterranean Sea. Because of that, he was known as the “Prophet of the North”. This vision, seen as a paradox, demonstrates Vilhjalmur Stefansson´s futurist perspective about the potentialities of the Arctic Ocean. A prophetic future confirmed by scientists who have been claiming: the possibility of new maritime routes and access to resources. In what concerns the maritime routes, in the 16^th and 17^th centuries, it was thought that travelling from China to the North Atlantic was possible. An idea confirmed in the 21^st century. 

The transformations provoked by climate change altered the collective and individual imaginary of the Arctic, allowing an opening to the external world, and bringing a new focus in the 21^st century. A focus was verified in different periods of world history, especially during World War II and the Cold War, as the Arctic was considered a geostrategic point for access and security in the region. This way, after the Cold War, cooperation was developed being a region of common interest of the Arctic States. With indigenous communities’ adaptability derived from the melting ice, a similarity between the Arctic Ocean and the Mediterranean Sea can be confirmed: the rapprochement and connection of the communities within global interactions. The Arctic is not periphery anymore.

Reference: Villalobos Dantas, S. (2024). The Polar Mediterranean Imaginary. A Renewed Paradigm by Vilhjalmur Stefansson. Nordicum-Mediterraneum. Icelandic E-Journal of Nordicum and Mediterranean Studies.

https://nome.unak.is/wordpress/author/santi

Author: Céline Rodrigues