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

In this study, researchers analysed two deep-sea fish species from South Georgia: Antimora rostrata (blue antimora), a more pelagic species, and Macrourus holotrachys (bigeye grenadier), a demersal species. In 2020, individuals were collected and four tissues (muscle, brain, liver and gills) were analysed, along with stable isotopes, to determine the habitat and trophic position of each species.

The results showed that:

• Muscle was the tissue with the highest mercury concentrations in both species.
• A. rostrata consistently showed lower concentrations than M. holotrachys.
• Only in M. holotrachys did Hg concentrations increase with body length and weight, suggesting bioaccumulation throughout life
• Differences also reflected habitat use, since the demersal species (M. holotrachys) is more closely associated with benthic food webs, which are generally richer in Hg.
• A. rostrata occupies a lower trophic level than M. holotrachys.

Unexpectedly, the brain showed high Hg concentrations, raising questions about potential neurotoxic effects in these fishes and their predators.

These results reveal that different feeding strategies and habitats shape contaminant accumulation in deep-sea species, with implications for ecosystem health and for top predators that depend on them.

Source: Vaz, D. B., Queirós, J. P., Xavier, J. C., Bustamante, P., Abreu, J., Pereira, E., Hollyman, P. R., Coelho, J. P. & Seco, J. (2025). Mercury Concentrations, Habitat and Trophic Position of Antimora Rostrata and Macrourus Holotrachys from South Georgia (Southern Ocean). Marine Pollution Bulletin. DOI:10.2139/ssrn.5360416

Author: Diana

Because squids are almost impossible to study alive, scientists have to rely on their beaks, hard structures that resist digestion and accumulate in the stomachs of predators to analyse their chemical signatures. In this study, researchers analysed squid beaks collected from the 1970s to the present day to measure mercury concentrations.

The results were remarkable, despite high mercury levels in the first two decades, concentration have been steadily decreasing over the past three decades. This trend suggests that global efforts to reduce mercury emissions, such as the International Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (1972)and improvements in industrial practices, are having measurable positive effects, even in remote ecosystems like the Southern Ocean (Figure 1).

Cephalopods like M. longimana can be valuable bioindicators as they occupy a central position in marine food webs, linking smaller prey such as crustaceans and fish to large predators like seals and whales. Moreover, their short lifespan and rapid make them excellent “record keepers” of environmental conditions giving researchers a unique window into pollutant trends.

By turning squid beaks into environmental archives, scientists have provided evidence that pollution can decline when collective action is taken. These results bring hope, but also serve as a reminder of the need to sustain global commitments to pollution reduction to safeguard ecosystems.

Source: Sara Lopes-Santos, José C. Xavier, José Abreu, José Seco, João P. Coelho, Eduarda Pereira, Richard A. Phillips, José P. Queirós, Decreasing mercury concentrations in beaks of the giant warty squid Moroteuthopsis longimana in the Scotia Sea (Southern Ocean) since the 1970s, Marine Pollution Bulletin, Volume 221, 2025, 118578, ISSN 0025-326X

Author: Lucas

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

One such squid species, Moroteuhopsis longimana, inhabits the deep waters of the Southern Ocean and can reach more than 2 meters in total length. It bioaccumulates Hg throughout its life and is an important prey item for several top predators such as seabirds, marine mammals and fish, so understanding its role in the transfer of Hg in the food web is crucial. However, there is still a lack of knowledge about the relationship between Hg concentrations in M. longimana beaks and muscle (the main tissue consumed by the predators), which this study aims to analyse.

To do that, 21 buccal masses of M. longimana collected from the stomach of the Antarctic toothfish (Dissostichus mawson). For total Hg analysis, the upper and lower beaks were sectioned into the wing (W) and hood tip (H), and the remainder of the lower (L) and upper (U) beaks (Figure 1). A portion of the buccal mass muscle (M) was also collected for analysis.

Results showed that Hg concentrations in the muscle are ~100 times higher than in the whole beaks (U and L) and ~50 times higher than in the W and H sections (Figure 2). Inter-tissue variability in Hg concentrations confirms that the concentration of Hg in the beak does not reflect directly those in the muscle.

However, a positive relationship was found between Hg concentrations in the wing (W) and muscle (M), translated by the following equation:

Hg_músculo = 34.88 Hg_asa + 0.12

This equation suggests that mercury concentration in the wing can be used as a proxy for Hg concentration in the muscle of M. longimana. However, it should only be used for adult individuals, as this study only used fully chitinized adult beaks.

Future studies can now use this equation to estimate the Hg concentration in the muscle of other M. longimana, through the analysis of the Hg concentration in the beak wing, providing a means of assessing the levels, transport and fate of Hg in within Southern Ocean ecosystem.

Source: Lopes-Santos S, Xavier JC, Seco J, Coelho JP, Hollyman PR, Pereira E, Phillips RA, Queirós JP (2025) Squid beaks as a proxy for mercury concentrations in muscle of the giant warty squid Moroteuthopsis longimana. Marine Environmental Research 204:106841.

Author: Sara Santos

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