Crabeater Seals Research Articles

Sea-ice and macrozooplankton distribution as determinants of top predator community structure in Antarctic winter

The Antarctic Peninsula marine ecosystem is highly productive, with large populations of commercially and ecologically important species including Antarctic krill Euphausia superba, Adélie penguins Pygoscelis adeliae, and crabeater seals Lobodon carcinophagus. The ecology of the peninsula is rapidly changing due to accelerating climate change and fishing pressure. Systematic ecosystem surveys have focused on austral spring and summer, leaving an information gap on winter ecosystem dynamics. Using data from 5 consecutive ecosystem surveys, we quantified the composition and distribution of winter predator communities and investigated the physical and biological influences on community structure. Seabirds and marine mammals clustered into 3 communities: an ice-associated community represented by Adélie penguins and crabeater seals; a diverse marginal ice zone community dominated by fur seals and several species of seabirds including 3 petrels, kelp gulls Larus dominicanus, and Antarctic terns Sterna vittata; and an open water community consisting of southern fulmars Fulmarus glacialoides and 4 species of petrels. These communities were distributed along an environmental gradient ranging from ice-covered, cold, saline water to ice-free, warmer, and fresher water with greater chlorophyll concentrations. Predator communities were also associated with different communities of macrozooplankton: ice-associated predators with an extremely diverse assemblage of typically mesopelagic zooplankton; marginal ice zone predators with a community of large-bodied euphausiids (E. superba, E. crystallorophias); and open water predators with a community of small-bodied euphausiids (Thysanoessa macrura). Our synthesis of integrated winter predator and macrozooplankton communities relative to sea-ice concentration provides reference points for future ecosystem assessments within this rapidly changing region.

Metabolomics approach for predicting stomach and colon contents in dead Arctocephalus pusillus pusillus, Arctocephalus tropicalis, Lobodon carcinophaga and Ommatophoca rossii from sub-Antarctic region.

The dietary habits of seals play a pivotal role in shaping management and administration policies, especially in regions with potential interactions with fisheries. Previous studies have utilized various methods, including traditional approaches, to predict seal diets by retrieving indigestible prey parts, such as calcified structures, from intestines, feces, and stomach contents. Additionally, methods evaluating nitrogen and stable isotopes of carbon have been employed. The metabolomics approach, capable of quantifying small-scale molecules in biofluids, holds promise for specifying dietary exposures and estimating disease risk. This study aimed to assess the diet composition of five seal species-Arctocephalus pusillus pusillus, Lobodon carcinophaga, Ommatophoca rossii, and Arctocephalus tropicalis 1 and 2-by analyzing stomach and colon contents collected from stranded dead seals at various locations. Metabolite concentrations in the seal stomach and colon contents were determined using Nuclear Magnetic Resonance Spectroscopy. Among the colon and stomach contents, 29 known and 8 unknown metabolites were identified. Four metabolites (alanine, fumarate, lactate, and proline) from stomach contents and one metabolite (alanine) from colon contents showed no significant differences between seal species (p>0.05). This suggests that traces of these metabolites in the stomach and colon contents may be produced by the seals' gut microbiome or derived from other animals, possibly indicating reliance on fish caught at sea. Despite this insight, the cause of death for stranded seals remains unclear. The study highlights the need for specific and reliable biomarkers to precisely indicate dietary exposures across seal populations. Additionally, there is a call for the development of relevant metabolite and disease interaction networks to explore disease-related metabolites in seals. Ultimately, the metabolomic method employed in this study reveals potential metabolites in the stomach and colon contents of these seal species.

Anthropogenic debris in three sympatric seal species of the Western Antarctic Peninsula

Litter pollution is a growing concern, including for Antarctica and the species that inhabit this ecosystem. In this study, we investigated the microplastic contamination in three seal species that inhabit the Western Antarctic Peninsula: crabeater (Lobodon carcinophaga), leopard (Hydrurga leptonyx) and Weddell (Leptonychotes weddellii) seals. Given the worldwide ubiquity of this type of contaminant, including the Southern Ocean, we hypothesized that the three seal species would present anthropogenic debris in their feces. We examined 29 scat samples of crabeater (n = 5), leopard (n = 13) and Weddell (n = 11) seals. The chemical composition of the items found were identified using micro-Raman and micro-FTIR spectroscopies. All the samples of the three species presented anthropic particles (frequency of occurrence - %FO – 100 %). Fibers were the predominant debris, but fragments and filaments were also present. Particles smaller than 5 mm (micro debris) were predominant in all the samples. Leopard seals ingested significantly larger micro-debris in comparison with the other seal species. The dominant color was black followed by blue and white. Micro-Raman and micro-FTIR Spectroscopies revealed the presence of different anthropogenic pigments such as reactive blue 238, Indigo 3600 and copper phthalocyanine (blue and green). Carbon black was also detected in the samples, as well as plastic polymers such as polystyrene, polyester and polyethylene terephthalate (PET), polyamide, polypropylene and polyurethane These results confirm the presence of anthropogenic contamination in Antarctic seals and highlight the need for actions to mitigate the effects and reduce the contribution of debris in the Antarctic ecosystem.

Incidental pinnipeds at high latitudes of the Vestfold Hills, Prydz Bay, East Antarctica

AbstractSpecies distributions are predicted to change with future climate-associated ecosystem changes such that so-called ‘vagrant’ individuals may become established or re-establish in areas currently thought to be beyond their principle ranges. Survey data were collated for occurrences of pinniped (seal) species at very high latitudes of the Vestfold Hills, East Antarctica. Aside from Weddell seals (Leptonychotes weddellii) and southern elephant seals (Mirounga leonina), which aggregate annually at the Vestfold Hills to breed and/or moult, three other pinniped species were observed with the recession of the fast-ice edge. Leopard seal (Hydrurga leptonyx) occurrences increased with an increase in a seasonally abundant prey resource, and crabeater seals (Lobodon carcinophaga) were seen at a time that coincides with their moult period. Occurrences of sub-adult male Antarctic fur seals (Arctocephalus gazella) increase the known southward range for this species and may reflect population increases at source populations in the Kerguelen Plateau area. Although there were no direct sightings of Ross seals (Ommatophoca rossii), their presence close to the Vestfold Hills was detected by underwater passive acoustic monitoring. Sightings of obligate drift-ice species and sub-Antarctic fur seals may change at the Vestfold Hills with climate-mediated changes in sea-ice conditions.

Species classification of Antarctic pack‐ice seals using very high‐resolution imagery

AbstractWe introduce a semiautomated machine learning method that employs high‐resolution imagery for the species‐level classification of Antarctic pack‐ice seals. By incorporating the spatial distribution of hauled‐out seals on ice into our analytical framework, we significantly enhance the accuracy of species identification. Employing a Random Forest model, we achieved 97.4% accuracy for crabeater seals and 98.0% for Weddell seals. To further refine our classification, we included three linearity measures: mean distance to a group's regression line, straightness index, and sinuosity index. Additional variables, such as the number of neighboring seals within a 250 m radius and distance of individual seals to the sea ice edge, also contributed to improved accuracy. Our study marks a significant advancement in the development of a cost‐effective, unified Antarctic seal monitoring system, enhancing our understanding of seal spatial behavior and enabling more effective population tracking amid environmental changes.

Simulating impacts of fishing toothfish on the pelagic community in the Cooperation Sea, Southern Ocean

There is increasing attention to the use of Antarctic toothfish (Dissostichus mawsoni) and Patagonian toothfish (Dissostichus eleginoides). Understanding the responses of toothfish and other species to fishing activities favors the sustainable use of natural resources. We developed an end-to-end model OSMOSE-CooperationSea to simulate the food web dynamics in the Cooperation Sea and evaluate the impact of toothfish fishery. Fishes and cephalopods played important roles in the energy pathways from krill species and other zooplankton species to toothfish and Weddell seal (Leptonychotes weddellii) whose trophic levels were higher than 5.0. Adélie penguin (Pygoscelis adéliae), Crabeater seal (Lobodon carcinophaga), and Baleen whales were strongly krill-reliant. The spawning stock of toothfish decreased more quickly than the recruitments with increasing fishing pressure. Fishing impacts on the recruitments of toothfish were hysteretic due to the fishing selectivity. The model considered an ontogenetic diet shift of toothfish that mesopelagic fish was influential to toothfish juveniles. The overexploitation of toothfish stock might result in a trophic cascade that mesopelagic fish biomass increased and krill biomass declined. Adélie penguin, Crabeater seal, and Baleen whales preyed on more small fishes in response to the decline of krill biomass. Considering the impacts of changes in Antarctic krill availability, the biomass of Adélie penguin, Crabeater seal, and Baleen whales declined with a heavy toothfish fishery. The study highlights the importance of precautionary and ecosystem-based management to toothfish fishery.

Large and in charge: cortisol levels vary with sex, diet, and body mass in an Antarctic predator, the leopard seal

Evaluating physiological responses in the context of a species’ life history, demographics, and ecology is essential to understanding the health of individuals and populations. Here, we measured the main mammalian glucocorticoid, cortisol, in an elusive Antarctic apex predator, the leopard seal (Hydrurga leptonyx). We also examined intraspecific variation in cortisol based on life history (sex), morphometrics (body mass, body condition), and ecological traits (δ15N, δ13C). To do this, blood samples, life history traits, and morphometric data were collected from 19 individual leopard seals off the Western Antarctic Peninsula. We found that adult leopard seals have remarkably high cortisol concentrations (100.35 ± 16.72 μg/dL), showing the highest circulating cortisol concentration ever reported for a pinniped: 147 μg/dL in an adult male. Leopard seal cortisol concentrations varied with sex, body mass, and diet. Large adult females had significantly lower cortisol (94.49 ± 10.12 μg/dL) than adult males (120.85 ± 6.20 μg/dL). Similarly, leopard seals with higher isotope values (i.e., adult females, δ15N: 11.35 ± 0.69‰) had lower cortisol concentrations than seals with lower isotope values (i.e., adult males, δ15N: 10.14 ± 1.65‰). Furthermore, we compared cortisol concentrations across 26 closely related Arctoid taxa (i.e., mustelids, bears, and pinnipeds) with comparable data. Leopard seals had the highest mean cortisol concentrations that were 1.25 to 50 times higher than other Arctoids. More broadly, Antarctic ice seals (Lobodontini: leopard seal, Ross seal, Weddell seal, crabeater seal) had higher cortisol concentrations compared to other pinnipeds and Arctoid species. Therefore, high cortisol is a characteristic of all lobodontines and may be a specialized adaptation within this Antarctic-dwelling clade. Together, our results highlight exceptionally high cortisol concentrations in leopard seals (and across lobodontines) and reveal high variability in cortisol concentrations among individuals from a single location. This information provides the context for understanding how leopard seal physiology changes with life history, ecology, and morphology and sets the foundation for assessing their physiology in the context of a rapidly changing Antarctic environment.

Winter records of killer whales (Orcinus orca) in the waters of the Wilhelm archipelago, West Antarctica

Killer whales (Orcinus orca (Linnaeus, 1758); KWs) are apex marine predators. In Antarctica, they have diverse trophic interactions and belong to five known ecotypes that have substantial differences in morphology, ecology, and acoustic repertoire. Around the Antarctic Peninsula, two distinct sympatric forms of Type B KWs are the most common. Both ecotypes have similar pigmentation patterns, but the larger form has been observed to feed mainly on seals (B1), and a smaller form feed on Pygoscelis penguins (B2). The waters of the West Antarctic Peninsula are experiencing marine ecosystem transformations caused by climate change at one of the fastest rates on Earth. Little is known about the austral winter distribution and ecology of KWs in this changing environment. The purpose of the present study was to reveal the winter distribution and ecology patterns of KWs in the waters of the Wilhelm Archipelago. Boat-based visual and photo-identification observations were performed. The boat cruises were conducted within 14 nautical miles of the Ukrainian Akademik Vernadsky Research Station, Galindez Island. In 2019, 10 surveys of a total of 194 nm were conducted: 4 trips in June and 6 in July. In 2021, 37 surveys of a total of 605 nm were conducted: 12 trips in June, 14 in July, and 11 in August. Surveys were performed when the ice conditions were suitable. During both winters, we managed to record only three groups of KWs. A group of 7 KWs was encountered on 27 June 2019 near Hovgaard and Pleneau islands. The group consisted of adults of both sexes and juvenile individuals. In the same area, on 13 July 2021, another group of KWs was observed, consisting of at least 5 individuals (up to 7). This group included 1 adult male, 2 adult females, a calf, and a juvenile of unknown sex. A comparison of the photos showed different individuals in the two groups. According to the external morphology patterns, it was determined that both groups belong to Type B, most likely of a smaller form (B1). Large gatherings of Pygoscelis penguins were observed in this area during the winter in both years. On 22 July 2021, a group of KWs consisting of 2 adult males was observed in the Penola Strait. Detailed observations of their joint feeding on a crabeater seal (Lobodon carcinophaga Hombron & Jacquinot, 1842) were collected. According to external morphology patterns and behaviour, they belong to a large form of Type B ecotype (B2). As Antarctic krill (Euphausia superba Dana, 1850) move inshore during winter, the Pygoscelis penguins and crabeater seals likely took advantage of ice-free areas to feed on it, and their gatherings could attract KWs of both Type B ecotypes. Future work should include collecting photogrammetry data, skin biopsy samples, feeding behaviour observations, and acoustic recordings to clearly differentiate between KW ecotypes and better understand their winter distribution and ecological patterns in this rapidly changing marine ecosystem.

In-air acoustic repertoire and associated behaviour of wild juvenile crabeater seals during rehabilitation

ABSTRACT In-air sounds of pinnipeds are important for interactions with conspecifics and threat displays. However, little is known about the in-air acoustic repertoire and associated behaviour of crabeater seals Lobodon carcinophaga. We investigated the in-air acoustic repertoire and associated behaviour of two male and one female wild juvenile crabeater seals that beached separately, and were rehabilitated in Durban and Gqeberha, South Africa. In-air sounds were visually identified and categorised into five classes validated via random forest model classification: brief, intermediate, and long moan calls, croaks, and hisses. Hisses were common (n = 25,105 sounds from 136 hrs of acoustic recordings) and detected during heightened arousal states and interactions with animal care staff and a conspecific. Furthermore, hisses were also recorded in low arousal states during exhalation. Moan calls (n = 241) were only detected from two of the three seals. During rehabilitation, the female seal ceased producing moan calls and later produced a series of croaks (n = 204). Acoustic characteristics of in-air moan calls differed from published underwater moan calls according to duration, minimum, and maximum frequencies, and pulse repetition rate. Our study shows that the in-air acoustic repertoire and associated behaviour of these Antarctic seals are dynamic, vary inter-individually and are context dependent.

Projecting environmental and krill fishery impacts on the Antarctic Peninsula food web in 2100

The Antarctic Peninsula ecosystem is extremely sensitive to climatic variability and other anthropogenic perturbances ascribed to biomass extraction by fisheries. An Ecopath with Ecosim model calibrated for the 1996–2012 period was projected into the future (2100) under three different climate projections for environmental variables (sea ice extent, open water area and chlorophyll-a concentration) and three Antarctic krill fishery scenarios (no-take, constant and decadal increase until doubling of the current catches). The relative impact of different drivers controlling Antarctic food web dynamics was evaluated with a sensitivity analysis and the temporal variability of several functional group and ecosystem indicators. Under these scenarios, environmental variability resulted in a greater impact on the Antarctic food web in 2100 projections compared with the krill fishery. Chlorophyll-a biomass strongly influenced the temporal variability of functional groups, suggesting predominant bottom-up control on the food web. An alternative food web structure was observed in 2100, with a marked decline in krill population biomass (from<50% to near extinction depending on the environmental projection) and an increase in salps and other zooplankton groups. A reduction in the biomass of sea ice and krill-dependent predators, such as Adélie and chinstrap penguins and crabeater seals, was also observed. The absence of functions modelling the spatial and seasonal variability of the krill fishery might cause an underestimation of its ecosystem impacts. This work provides useful insights into the dynamic responses of the Antarctic food web under likely environmental projections and highlights critical points that need to be addressed to improve the understanding and parametrization of the Antarctic food web to anticipate future variability.

Exploring fungal diversity in Antarctic wildlife: isolation and molecular identification of culturable fungi from penguins and pinnipeds

Aims: To survey the diversity of fungal species that may be cultured from Antarctic penguins and pinnipeds, and to test the in vitro susceptibility to triazole drugs of any medically important Aspergillus isolates. Methods: During an expedition to Argentinean Antarctic research stations at Potter Peninsula (South Shetland Islands) and Primavera Cape (Antarctic Peninsula) in February 2019, samples (n = 212) were collected from fur seals (Arctocephalus gazella), elephant seals (Mirounga leonine), leopard seals (Hydrurga leptonyx), Weddell seals (Leptonychotes weddellii) and crabeater seals (Lobodon carcinophaga) and gentoo penguins (Pygoscelis papua). Oral, nasal and rectal swabs and skin/hair brushings were collected from pinnipeds, and skin/feather brushings, cloacal swabs and moulted feathers from penguins. Samples were cultured on Sabouraud dextrose agar and/or potato dextrose agar plates and fungal isolates identified by morphological criteria followed by PCR amplification and DNA sequencing. Antifungal susceptibility of Aspergillus spp. isolates to triazoles was tested. Results: Fungi from 21 genera were isolated from 121/212 (57.1%) samples obtained from pinnipeds and penguins. Among pinnipeds from Potter Peninsula (fur seals and elephants seals), the most frequent fungal species were Debaryomyces hansenii and Rhodotorula mucilaginosa, isolated from the oral, nasal and/or rectal mucosa, and Antarctomyces psychrotrophicus isolated from the skin/hair of all sampled individuals. Among pinnipeds from Primavera Cape (leopard seals, Weddell seals and crabeater seals), the most frequent fungal species were Naganishia adeliensis and Cryptococcus neoformans var. uniguttulatus, isolated from the nasal/oral mucosa of 4/33 (15.2%) and 5/33 (12.1%) animals, respectively. The most frequently isolated fungal species from gentoo penguins (Potter Peninsula), were Pseudogymnoascus pannorum and A. pyschrotrophicus, which both were isolated from skin/feathers of 7/15 (46.7%) birds, and Thelebolus microsporus, isolated from the cloacal mucosa and skin/feathers of 5/15 (33.3%) and 2/15 (13.3%) birds, respectively. Fungi that are potentially pathogenic to both humans and animals, (Aspergillus fumigatus, Asp. flavus, Asp. versicolor, Candida parapsilosis and Microsporum canis) were isolated from 4/38 (10.5%), 1/38 (2.6%), 2/38 (5.3%), 4/38 (10.5%) and 2/38 (5.3%) sampled pinnipeds, respectively. Only non-azole-resistant isolates of Asp. fumigatus and Asp. flavus were identified. Conclusions: The fungal biodiversity in Antarctic pinnipeds and gentoo penguins was explored using standard mycological culture followed by PCR and DNA sequencing. The frequency of fungal carriage varied among animal species, sample type and location. This study constitutes an epidemiologic approach to monitoring of these marine animals for emerging fungal pathogens.

Fragmented mitochondrial genomes of seal lice (family Echinophthiriidae) and gorilla louse (family Pthiridae): frequent minichromosomal splits and a host switch of lice between seals

BackgroundThe mitochondrial (mt) genomes of 15 species of sucking lice from seven families have been studied to date. These louse species have highly dynamic, fragmented mt genomes that differ in the number of minichromosomes, the gene content, and gene order in a minichromosome between families and even between species of the same genus.ResultsIn the present study, we analyzed the publicly available data to understand mt genome fragmentation in seal lice (family Echinophthiriidae) and gorilla louse, Pthirus gorillae (family Pthiridae), in particular the role of minichromosome split and minichromosome merger in the evolution of fragmented mt genomes. We show that 1) at least three ancestral mt minichromosomes of sucking lice have split in the lineage leading to seal lice, 2) one minichromosome ancestral to primate lice has split in the lineage to the gorilla louse, and 3) two ancestral minichromosomes of seal lice have merged in the lineage to the northern fur seal louse. Minichromosome split occurred 15-16 times in total in the lineages leading to species in six families of sucking lice investigated. In contrast, minichromosome merger occurred only four times in the lineages leading to species in three families of sucking lice. Further, three ancestral mt minichromosomes of sucking lice have split multiple times independently in different lineages of sucking lice. Our analyses of mt karyotypes and gene sequences also indicate the possibility of a host switch of crabeater seal louse to Weddell seals.ConclusionsWe conclude that: 1) minichromosome split contributes more than minichromosome merger in mt genome fragmentation of sucking lice, and 2) mt karyotype comparison helps understand the phylogenetic relationships between sucking louse species.

Weights of some organs of crabeater seals, Lobodon carcinophaga

Weights of some organs of crabeater seals, Lobodon carcinophaga

Lobodon carcinophagus

This datasheet on Lobodon carcinophagus covers Identity, Distribution.

Acoustic analysis of crabeater seal (Lobodon carcinophaga) vocalizations in the Southern Kerguelen Plateau region of East Antarctica.

Crabeater seals are circumpolar, ice-dependent seals that produce distinct vocalizations during the breeding season. This study provides the first description of the acoustic repertoire of the crabeater seal in East Antarctica, using data from a stationary hydrophone at 1.8 km depth in the Southern Kerguelen Plateau region in 2014-2015. Two call types were identified in the data set: the low and the high moan calls. Of the 8821 calls detected, 92.5% were classified as low moan calls and 7.5% were high moan calls. The mean duration of the two call types was similar (2.3 and 2.8 s, respectively), however, the high moan calls had a higher frequency range (1020-4525 Hz, n = 11) than the low moan calls (360-2753 Hz, n = 120). The calls were primarily detected in the austral spring. Diel analysis showed that the low moan calls were mostly made at nighttime or proximal to dusk and dawn. The results of this study could aid in the development of automated detectors for crabeater seal vocalizations. This would facilitate comparisons of the distribution and abundance of the species using extant acoustic data and could increase knowledge on the breeding behavior of crabeater seals.

Complementary use of stable isotopes and fatty acids for quantitative diet estimation of sympatric predators, the Antarctic pack-ice seals

The quantitative use of stable isotopes (SIs) for trophic studies has seen a rapid growth whereas fatty acid (FA) studies remain mostly qualitative. We apply the Bayesian tool MixSIAR to both SI and FA data to estimate the diet of three sympatric predators: the crabeater (Lobodon carcinophaga), Weddell (Leptonychotes weddellii) and leopard seal (Hydrurga leptonyx). We used SI data of their vibrissae and FA data of their outer blubber to produce comparable diet estimates for the same individuals. Both SI and FA models predicted the same main diet components, although the predicted proportions differed. For the crabeater seal, both methods identified krill, Euphausia superba, as the main, and almost exclusive, food item, although the FA model estimated a slightly lower proportion, potentially due to the low lipid content of krill compared to the fish species used in the model. For the Weddell seal the FA model identified the fish Pleuragramma antarcticum as the most important prey, whereas the SI model was not able to distinguish among prey species, identifying a ‘fish-squid’ group as the main diet component. For the leopard seal, both models identified krill as the main contributor; however, the predicted proportions for the secondary sources differed. Although vibrissae and outer blubber may not represent the same timeframe, the use of MixSIAR with FA data provides diet estimates comparable to those obtained with SI data, thus, both approaches were complimentary. The use of both biotracers offers a feasible option to study diets of wild animals in a quantitative manner.

Ice matters: Life-history strategies of two Antarctic seals dictate climate change eventualities in the Weddell Sea.

The impacts of climate change in Antarctica and the Southern Ocean are not uniform and ice‐obligate species with dissimilar life‐history characteristics will likely respond differently to their changing ecosystems. We use a unique data set of Weddell Leptonychotes weddellii and crabeater seals' (CESs) Lobodon carcinophaga breeding season distribution in the Weddell Sea, determined from satellite imagery. We contrast the theoretical climate impacts on both ice‐obligate predators who differ in life‐history characteristics: CESs are highly specialized Antarctic krill Euphausia superba predators and breed in the seasonal pack ice; Weddell seals (WESs) are generalist predators and breed on comparatively stable fast ice. We used presence–absence data and a suite of remotely sensed environmental variables to build habitat models. Each of the environmental predictors is multiplied by a ‘climate change score’ based on known responses to climate change to create a ‘change importance product’. Results show CESs are more sensitive to climate change than WESs. Crabeater seals prefer to breed close to krill, and the compounding effects of changing sea ice concentrations and sea surface temperatures, the proximity to krill and abundance of stable breeding ice, can influence their post‐breeding foraging success and ultimately their future breeding success. But in contrast to the Ross Sea, here WESs prefer to breed closer to larger colonies of emperor penguins (Aptenodytes forsteri). This suggests that the Weddell Sea may currently be prey‐abundant, allowing the only two air‐breathing Antarctic silverfish predators (Pleuragramma antarctica) (WESs and emperor penguins) to breed closer to each other. This is the first basin‐scale, region‐specific comparison of breeding season habitat in these two key Antarctic predators based on real‐world data to compare climate change responses. This work shows that broad‐brush, basin‐scale approaches to understanding species‐specific responses to climate change are not always appropriate, and regional models are needed—especially when designing marine protected areas.

The status of the fur seal population (Arctocephalus gazelle) on the southern border of the distribution area (the Argentine Islands archipelago)

The study of the population status of Arctocephalus gazella (Peters, 1875) in waters of the Argentine Islands was carried out in the period from April 2015 to March 2016 in accordance with the objectives of the State Target Scientific and Technical Research Program of Ukraine in Antarctica for 2011–2020. The aim of the article is to study the population dynamics and distribution of the southern fur seal in waters of the Argentine Islands. Due to the lack of data on the specifics of the seal’s dispersal in different periods of the year and the dynamics of the species population at the southern border of the distribution range, the results of the research are relevant and of great importance. In the second half of the 20th century, some publications presented the results of monitoring of pinnipeds at the Argentine Islands and adjacent territories, but the objects of these studies usually were other seal species: Hydrurga leptonyx, Lobodon carcinophagus, Leptonychotes weddelli, and Mirounga leonina. In the early 21st century, monitoring of the fauna of the Argentine Islands was carried out by Ukrainian biologists. However, they focused on Leptonychotes weddelli and less on other species of pinnipeds. The field material was collected in waters of the Argentine Islands, which is located in the Pacific sector of Antarctica. The fur seal population census and distribution studies were conducted according to the generally accepted methods. After breeding season on the subantarctic islands, during the migration southwards, fur seals reach the Argentine Islands, usually in the third decade of January. In the summer of 2016, the first fur seal was recorded within the archipelago on 31 January. During the study period, the largest number of animals within the archipelago was recorded in March–April and it ranged from 300 to 400 individuals. On the islands of the archipelago, the main resting places of seals were identified. The movement of animals northwards starts in May, consequently a decrease in the number of animals in this region is observed at that time. The last individuals are recorded in the first half of August. In 2015, migration began in May and ended in early August. There are several periods that were characterized by intensive migration of the animals: late June, 5–8 July, and 29 July to 6 August. In winter, one individual was last found within the archipelago on 12 August. The migration is launched by the worsening of weather conditions, formation of a continuous ice cover, reduced availability of food, and other factors.

Very Low Density and Biodiversity of Seabird and Marine Mammal at-sea Distribution in the Amundsen Sea, 2010

Our long-term study on the quantitative at-sea distribution of the upper trophic levels - seabirds and marine mammals - in polar ecosystems aims at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal changes, with special attention to hydrography and global climate changes. During the ANT- XXVI/3 expedition of icebreaking RV Polarstern in February-March 2010, a total of 8,270 seabirds belonging to 15 identified species were recorded in the Amundsen Sea during 1,070 half-hour transect counts, with a mean of eight birds per count. The most numerous species were by far Antarctic petrel, Adélie penguin and snow petrel, which together accounted for more than 80% of all individuals of these species recorded. Substantial hotspots of seabirds perched on three icebergs, representing 44% of all observations: 85% of the Antarctic petrels and 40% of the snow petrels [1]. Without taking into account these data, the mean seabird number becomes five individuals per count, representing the lowest value registered in Antarctic seas. The most numerous pinniped was crabeater seal contributing 98% of the total of 2,350 individuals of four pinniped species [2]. Among cetaceans, the most abundant species were Antarctic Minke whale and fin whale (60% and 25% of the total of 170 individuals, four species). The maps allow for a visual comparison that is sufficient for the purposes of this article, reflecting the influence of hydrological features such as water masses and fronts, pack ice and ice edge, free drifting icebergs.

Publisher Correction: Projected shifts in the foraging habitat of crabeater seals along the Antarctic Peninsula

Publisher Correction: Projected shifts in the foraging habitat of crabeater seals along the Antarctic Peninsula