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 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 pressures caused by climate change will shape the biological communities along the NAP. At the base of the food chain, the effects of the changes will have consequences on the phytoplankton morphology and could even alter the phytoplankton communities in the region under study.

Although the response of local phytoplankton communities is expected to vary in the short and long term, a general trend towards a smaller morphotype with flagella (tails) is expected. This may have consequences for the ecosystem (Figure 1), as the remaining elements, such as krill, may not be able to adjust to the changes. Climate change is projected to have a long-term impact on the community, potentially leading to further transformations.

Current knowledge of this region provides information on phytoplankton’s response to climate change and what may occur. To fully comprehend and predict the changes that will occur in the region’s communities, a combined effort is required.

The main knowledge gap in the NAP is the intrinsic and elusive link between anthropogenic climate change and natural climate variability. To assess the impact of climate change, we must distinguish between natural internal fluctuation and long-term changes.

To close this gap, several research directions must be taken in the future (Figure 2), as well as expanding the current sampling effort, for which we have various methods that could be used, such as animal-borne sensors, ocean colour satellites, biogeochemical floats, underwater gliders, and more expeditions on ships to collect in situ data.

It is critical to assess how potential changes in phytoplankton composition may impact well-being and normal ocean functions. Understanding phytoplankton responses to climate change will not be possible without a better understanding of phytoplankton physiology in the PNA, which requires conducting studies with various stressors such as light, salinity, and carbon dioxide, focusing on the responses of the main phytoplankton species to them. Obtaining this knowledge will require the collaboration of polar research programmes and the scientific community within a common research framework.

Reference: Ferreira A, Costa RR, Dotto TS, Kerr R, Tavano VM, Brito AC, Brotas V, Secchi ER and Mendes CRB (2020) Changes in Phytoplankton Communities Along the Northern Antarctic Peninsula: Causes, Impacts and Research Priorities. Front. Mar. Sci. 7:576254.

https://doi.org/10.3389/fmars.2020.576254

Author: G. Sofia Nunes

The authors focus on the giant warty squid Moroteuthopsis longimana, which is a major prey for Southern Ocean predators and has been previously studied for its age and growth using different techniques. The study aims to evaluate the feasibility of using beaks collected from predators’ stomachs, such as the Antarctic toothfish (Dissostichus mawsoni) to determine the age and growth of M. longimana and estimate the age and growth patterns of this species in different areas of the Southern Ocean.

The study found that beaks collected from predators’ stomachs can be used to study the age of Southern Ocean squids, specifically M. longimana. The rostrum sagittal section (RSS) of the lower beak was found to be the most reliable section for age estimation (Fig.1), as it had readable micro-increments that could be counted while the upper beaks presented highly compacted increments with many of them being indistinguishable. Also, it was estimated that M. longimana can live up to 820 days and may hatch throughout the year. This species showed a consistent growth rate from hatching to death with at least one period of faster growth. A novel pattern of regular cycles, composed of 7-10 lighter increments followed by a darker one, was found in the medium-anterior region of the RSS (Fig.2b). Differences in growth rate and size reached at the same age were observed between individuals from the Pacific and Atlantic sectors of the Southern Ocean, suggesting the influence of different environmental conditions.

Therefore, beaks collected from predators’ stomachs can be used to study the age and growth of Southern Ocean squid, specifically Moroteuthopsis longimana. However, the authors highlighted the need for future research to validate the periodicity of increment formation in cold-water and deep-sea squid and to consider the impact of environmental conditions on the growth of M. longimana.

Reference: Queirós, J. P., Bartolomé, A., Piatkowski, U., Xavier, J. C., & Perales-Raya, C. (2022). Age and growth estimation of Southern Ocean squid Moroteuthopsis longimana: can we use beaks collected from predators’ stomachs? Marine Biology, 170(1).

https://doi.org/10.1007/s00227-022-04156-2

Author: Diogo Francisco

The Antarctic toothfish (Dissostichus mawsoni), a long-lived top predator in the Southern Ocean, is captured annually in the region. Due to its biological and ecological features, D. mawsoni is susceptible to accumulate high concentrations of trace elements, making it a potential bioindicator for the concentrations of trace and rare earth elements in the deep-sea ecosystem of the Southern Ocean.

Considering the commercial interest of D. mawsoni, in this study the authors discuss how this species can be a good source of nutrients to consumers by also exploring if the different trace elements can be used to determine the origin of the fish. To accomplish this, it was determined for the first time the concentration of 27 trace and rare earth elements in muscle samples of the species D. mawsoni, which was caught in three areas of the Amundsen and Dumont D’Urville Seas in Antarctic (Figure 1).

As expected, the study revealed that major essential elements, particularly potassium (K), exhibited the highest concentrations, while rare earth elements registered the lowest levels in the D. mawsoni muscle. Notable differences were observed between the study areas, indicating that the concentration of these elements in this species varies geographically and within adjacent fishing areas, with highest levels identified in fish from the Amundsen Sea slope. The authors suggested that these disparities may be linked to dietary variations, differences in Southern Ocean water composition and contrasting trends in environmental changes that influence the input of some elements into the environment.

Additionally, by using otolith [1] lengths as a proxy for fish size and δ15N [2] values as an indicator of trophic position, the study found no evidence of bioaccumulation of those elements in the muscle of D. mawsoni. Instead, concentrations tended to decrease with fish size, suggesting potential influences from a growth dilution effect, metabolic and lipid content variations between younger and older fish, or habitat-related factors. Moreover, the absence of significant correlations with δ15N values indicates no biomagnification [3] potential within these food webs.

The later evaluation of the potential detoxification role of selenium (Se) for Mercury (Hg) in D. mawsoni was significant, specifically when mercury concentrations reach levels that could be harmful to the organism. This implies that selenium might play a crucial role in protecting the Antarctic toothfish from the adverse effects of elevated levels of Hg.

Thereby, according to these findings, D. mawsoni not only stands out as a bioindicator for the concentrations of the different trace and rare earth elements in the Southern Ocean, but also reveals itself as a good source of major essential elements to humans with concentrations of major essential elements above some of other marine fish worldwide.

Definitions:

[1] Otholits: Hard, calcium carbonate structures located directly behind the brain of bony fishes.

[2] δ15N: Nitrogen stable isotope, which allows for an estimation of the trophic position of consumers in a diet chain.

[3] Biomagnification: Increase in concentration of a substance in the tissues of organisms at successively higher levels in a food chain.

Reference: Queirós, J. P., Machado, J. F., Pereira, E., Bustamante, P., Carvalho, L., Soares, E., Stevens, D. W., & Xavier, J. C. (2023). Antarctic toothfish Dissostichus mawsoni as a bioindicator of trace and rare earth elements in the Southern Ocean. Chemosphere, 321, 138134. https://doi.org/10.1016/j.chemosphere.2023.138134

Author: Maria Soares

Thus, both due to their enormous quantity and the high energy values they contain (e.g.: omega 3), krill are the main prey for countless Antarctic species, from penguins, seals, whales, fish and many other species of albatrosses and petrels. In some of these species, krill can even represent more than 70% of the diet. Its ecological importance is therefore undeniable in this large ecosystem.

Finally, and as mentioned above, krill is an animal with characteristics that are also very beneficial for humans through medicines, as well as for other activities through fishmeal/aquaculture or natural fertilizers. In this way, there is a very active fishery that targets krill, making its management laborious and highly special.

Krill fishing has existed for over 50 years, mainly around the Antarctic Peninsula and the South Shetland Islands, South Orkney Islands and South Georgia. Initially more focused during the summer, it moved progressively to mainly operating in the winter. A measure aimed at avoiding competition between fishing and predators during the breeding season.

Its management is carried out by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which is based on biomass surveys. This is a representative sample of the potential biomass in a given area, then stipulating a maximum quota of krill. As a prevention and sustainability focus, CCAMLR states that 75% of the original biomass is maintained.

So, what is the difficulty in this management?

Much of the discussion about krill fishery management in CCAMLR has focused on protecting krill predators that breed on land and fishing operations.

On the other hand, in recent times, there has been relatively little discussion about the risks that fishing poses to the krill population itself. The view of sustainability to date is now challenged by the high levels of variability observed in available indices of krill abundance, particularly over the last two decades, which vary in magnitude and increasing fishing space, resulting in substantial local impacts.

Although the reproduction cycle is considerably known and studied, krill are quite dependent on both ocean currents, plus the locations and environmental conditions where juveniles develop. Hence, being where the problem lies today. With current climate change or the increasingly strong decline of sea ice, crucial in its development, krill recruitment has varied strongly between years, and this is expected to be subsequently reflected in the available biomass. Much of the previous research was carried out mainly in the summer, leaving a gap in its cycle in the winter phase. Fishing itself has evolved and today its capacity to extract krill from the water both spatially and in quantity is much faster, having much more sudden impacts on the population. In addition, this decreases in sea ice, opens new areas available to the fishing industry, which generate more pressure. The key thus lies in understanding the krill reproduction and development cycle with present environmental conditions and future perspectives. Both science and the fishing industry must work hand in hand, so that we have the most real value of the total krill biomass, and thus adjust and apply the best measures. In the end, is of upmost aim that the benefits for humans never corrupt the ecological and biological importance that this fantastic species has for the Southern Ocean and the entire Antarctic region.

Author: José Abreu

Source: Meyer, B., Atkinson, A., Bernard, K.S. et al. Successful ecosystem-based management of Antarctic krill should address uncertainties in krill recruitment, behaviour and ecological adaptation. Commun Earth Environ 1, 28 (2020). DOI: 10.1038/s43247-020-00026-1

To study the interactions between the wandering albatross and Southern Ocean fisheries, radar GPS-loggers were attached to the seabird individuals, along with information regarding the position and movements of fishing vessels. This study considered the different life stages and sex of the wandering albatross, which are usually under-researched or not considered in many studies.

The results showed that different types of gear used in fisheries make the visiting of the wandering albatross differ. The fisheries that use set (demersal) longliners had a higher likelihood of being visited by this seabird than other gear types (mainly trawlers, squid jiggers and drifting longliners).

When analysing the bycatch rate of different life stages of the wandering albatross, the results showed an increase in the visits of fishing vessels by the wandering albatross during the incubation period (Fig. 1). However, it’s important to note that if discards are not occurring this seabird won’t visit the vessel, in the case that prey is available in the surroundings.

In order to reduce mortality bycatch associated with fisheries of the wandering albatross and other vulnerable seabird species, it’s important to engage with the managers and operators of the main fisheries that come in contact with these species and implement best practices regarding seabird-bycatch mitigation, seabird bycatch rates and monitoring of compliance.

Source: Carneiro, A. P. B., Clark, B. L., Pearmain, E. J., Clavelle, T., Wood, A. G., & Phillips, R. A. (2022). Fine-scale associations between wandering albatrosses and fisheries in the southwest Atlantic Ocean. Biological Conservation, 276. DOI:  https://doi.org/10.1016/j.biocon.2022.109796

Author: Mariana Quitério

Barents Sea is an extremely rich habitat, with high primary productivity, making this place an important habitat for numerous species, such as marine sponges. Here, it is possible to find a large community of marine sponges, such as GeodiaBarretti. These are considered fundamental to the habitat and serve as natural indicators of Vulnerable Marine Ecosystems. However, the increasing rate of trawling is also increasing the damage to the sea floor, which is often irreversible.

This study aimed to analyze the effects of trawling on the abundance of Geodia spp. and diversity of associated fauna species. Therefore, were used images collected by an ROV (Remotely Operated Vehicle), of two locations with completely different levels of drag (location with low and heavy impact), which were compared. Through the analysis between the two locations, it is possible to verify the consequences that long-term trawling creates. In the place where trawling is not so frequent, it was possible to find a relatively diverse and abundant sponge community, in contrast to the place where trawling is more frequent.

Several studies have shown that the continuity of trawls in the same location leads to functional changes in benthic communities. Sponges have a high filtration rate, which allows them to remove a large amount of particles from the environment, including viruses and other pathogens. However, if the intensity of trawling continues to increase, and consequently to a decrease in the abundance of sponges in the Barents Sea, this habitat will experience an increase in the amount of particulate carbon deposited on the seafloor. With the increase in carbon, this location becomes more favourable for species that feed on dead organic matter. Which in turn leads to a change in the functional diversity of the system.

The authors concluded that bottom fishing significantly reduces sponge communities, reduces sponge abundance and size, and creates a change in species and functional diversity, and subsequently in ecosystem function and services.

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Source:Colaço, A., Rapp, H. T., Campanyà-Llovet, N., & Pham, C. K. (2022). Bottom trawling in sponge grounds of the Barents Sea (Arctic Ocean): A functional diversity approach. Deep Sea Research Part I: Oceanographic Research Papers, 183, 103742.

Author: Eva Lopes