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The ocean’s meso- and submeso-scales (1-100 km, days to weeks) host features like filaments and eddies that have a key structuring effect on phytoplankton distribution, but that due to their ephemeral nature, are challenging to observe. This problem is exacerbated in regions with heavy cloud coverage and/or difficult access like the Southern Ocean, where observations of phytoplankton distribution by satellite are sparse, manned campaigns costly, and automated devices limited by power consumption. Here, we address this issue by considering high-resolution in-situ data from 18 bio-logging devices deployed on southern elephant seals (Mirounga leonina) in the Kerguelen Islands between 2018 and 2020. These devices have submesoscale-resolving capabilities of light profiles due to the high spatio-temporal frequency of the animals’ dives (on average 1.1 +-0.6 km between consecutive dives, up to 60 dives per day), but observations of fluorescence are much coarser due to power constraints. Furthermore, the chlorophyll a concentrations derived from the (uncalibrated) bio-logging devices’ fluorescence sensors lack a common benchmark to properly qualify the data and allow comparisons of observations. By proposing a method based on functional data analysis, we show that a reliable predictor of chlorophyll a concentration can be constructed from light profiles (14 686 in our study). The combined use of light profiles and matchups with satellite ocean-color data enable effective (1) homogenization then calibration of the bio-logging devices’ fluorescence data and (2) filling of the spatial gaps in coarse-grained fluorescence sampling. The developed method improves the spatial resolution of the chlorophyll a field description from ~30 km to ~12 km. These results open the way to empirical study of the coupling between physical forcing and biological response at submesoscale in the Southern Ocean, especially useful in the context of upcoming high-resolution ocean-circulation satellite missions.

Research on immune response in polar fauna is gaining great importance due to different scenarios of environmental change. Total leukocyte counts in blood smears are one of the most widespread practices and provide useful information about the health status of individuals. However, there is no methodological agreement for these analyses. Total leukocyte counts can be performed at ×400 magnification in optical microscopy using 10,000 erythrocytes for standardizing. However, counting such number of erythrocytes is costly and time-consuming. Here, we describe a new technique to simplify leukocyte counts in blood smears from Antarctic wildlife based on the number of microscope fields instead of the number of erythrocytes which reduces considerably the time spent. We have counted total leukocytes using both methods in the three penguin species of the genus Pygoscelis—Adélie (P. adeliae), gentoo (P. papua), and chinstrap penguin (P. antarcticus)—and four Antarctic mammal species: crabeater seal (Lobodon carcinophaga), leopard seal (Hydrurga leptonyx), weddell seal (Leptonychotes weddellii), and southern elephant seal (Mirounga leonina) for validation. Our results show a high correlation between the total leukocyte counts using 10,000 erythrocytes or 10 microscope fields for standardizing. These results show the reliability of the latter method for counting the total number of leukocytes in different species of birds and mammals saving time and effort., The study was funded by the Spanish Ministry of Economy and Competitiveness through projects CTM2011-24427, CTM2015-64720, and PID2019-108597 and by the Dirección Nacional del Antártico, Instituto Antártico Argentino (PICTA 2010-01).

The first records of elephant seals, likely southern elephant seals, Mirounga leonina, are reported for the Colombian Pacific coast. A juvenile elephant seal was registered on the beaches of Pianguita and Maguipi (Valle del Cauca), from January 23-25, 2018. On 22 February 2018, a male juvenile, presumably the same animal, was also reported further north on the beaches of Guachalito (Choco). Then, a group of three individuals was sighted on the beach of El Medio, the mouth of the Yurumangui River (Valle del Cauca) from 29 December, 2019 to 20 January 2020; this sighting was confirmed on January 3, 2020, by recording a subadult male individual apparently in healthy body condition. Also, a dead subadult in advanced state of decomposition was found in the river Guapi in January 8, 2021. These sightings are among the most northern extralimital records for this species with a large displacement covering 5000–8000 Km from its normal distributional range that includes southern Chile and Antarctica. The presence of the southern elephant seal in the Colombian Pacific had not been documented, and the arrival of this species could be linked to the search for food and the influence of eco-physiological processes, as well as the impact of the ENSO and ongoing environmental changes in the Southern Ocean.

The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long‐term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long‐term mark‐recapture studies (1956–1967 and 1993–2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9‐state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population., This research investigated the influence of large‐scale climate modes (SAM and SOI) on female southern elephant seal survival (φ) by creating demographic models from historic capture‐mark‐recapture data. Map of the Southern Ocean from Tasmania (top) to East Antarctica and the Ross Sea (bottom) with Macquarie Island location marked by a small circle. Surrounding Antarctica, the Polar Front (blue line), 60th parallel south, (gray circle) and winter sea ice extent (white) are overlaid. Top right: Vegetation map of Macquarie Island (adapted from the Australian Antarctic Data Centre map no. 13106) and stylized illustration of a female southern elephant seal, Mirounga leonina (artwork by: Sophia Volzke).

Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf (~2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size (~2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade‐off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade‐off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea‐ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure., Partitioning resources is key to avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species partitioning can be due to either competition or the different resource needs of morphologically distinct individuals. Our study demonstrates that habitat partitioning in highly dimorphic species is the result of complex interplay of life history strategies, environmental conditions, and predation pressure.

An unusual sighting of a juvenile southern elephant seal (Mirounga leonina), outside its typical range, was recorded off the southern coast of Sri Lanka between 20th November and 20th December 2019. The individual, a male as confirmed by the presence of a prepuce, underwent a catastrophic moult during this 1 month period, following which no further observations were recorded and so it was assumed it returned to sea. This represents the first confirmed sighting of a southern elephant seal, and indeed a phocid, in Sri Lankan waters.

We present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months. Fil: Procksch, Natália. Universidad de Vale do Rio dos Sinos; Brasil Fil: Grandi, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Ott, Paulo Henrique. Universidade Estadual Do Rio Grande Do Sul; Brasil. Grupo de Estudos de Mamíferos Aquáticos Do Rio Grande Do Sul (GEMARS); Brasil Fil: Groch, Karina. Instituto Australis de Pesquisa E Monitoramento Ambiental. Projeto Baleia Franca; Brasil Fil: Flores, Paulo A. C.. Centro Mamíferos Aquáticos, Currently at Área de Proteção Ambiental; Brasil Fil: Zagonel, Marcelo. Universidad de Vale do Rio dos Sinos; Brasil Fil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Machado, Rodrigo. Grupo de Estudos de Mamíferos Aquáticos Do Rio Grande Do Sul (GEMARS); Brasil Fil: Pavez, Guido. Universidad de Valparaiso; Chile Fil: Guimarães, Murilo. Universidade Federal do Rio Grande do Sul; Brasil Fil: Veronez, Maurício. Universidad de Vale do Rio dos Sinos; Brasil Fil: de Oliveira, Larissa Rosa. Grupo de Estudos de Mamíferos Aquáticos Do Rio Grande Do Sul (GEMARS); Brasil. Universidad de Vale do Rio dos Sinos; Brasil

Introduction The pinnipeds’ placenta has been described as zonary, annular, labyrinthic and endotheliochorial, like that of the terrestrial carnivores. This article describes the placenta of Mirounga leonina, a phocid pinniped, focusing on some morphological features related to fetal nutrition. Methods Placental samples from three elephant seals were collected and conditioned after natural delivery at the Antarctic Specially Protected Area 132. Histological and ultrastructural studies were conducted; cytokeratins, vimentin, α-smooth muscle actin, and desmin proteins were detected using immunohistochemistry. Results The placentas were zonary, lobed, belt-shaped, and showed multiple vivid orange areas, which corresponded to bilirubin crystalline pigment found among chorionic villi and inside trophoblast cells. In the labyrinth, cytotrophoblast cells were isolated and there was a scant syncytium interposed between maternal and fetal vessels. Fetal vessels were small, round, and frequently intratrophoblastic, while maternal vessels were large, irregular, sinuous, and thin-walled. Vimentin and actin were detected in some scattered non-vascular cells throughout the labyrinth. Broad areas of degenerated and necrotic maternal components were also observed. Discussion The placentas of pinniped and fissiped carnivores share several traits. However, some remarkable features might maximize respiratory efficiency, collaborating to endure deep-diving hypoxia. Some of them, as the notably large sinuous maternal capillaries and fetal capillary indentation into the syncytium, are shared, e.g., by Phocidae and Mustelidae. Besides hemotropic nutrition taking place through an extremely narrow barrier, the abundant necrotic material and hematic products might allow substantial endocytosis of detritus even in term placentas, in this species giving birth to precocious offspring.

International audience; Biophysical interactions are influential in determining the scale of key ecological processes within marine ecosystems. For oceanic predators, this means foraging behaviour is influenced by processes shaping the distribution of prey. However, oceanic prey is difficult to observe and its abundance and distribution is regionally generalised. We use a spatiotemporally resolved simulation model to describe mid‐trophic prey distribution within the Southern Ocean and demonstrate insights that this modelled prey field provides into the foraging behaviour of a widely distributed marine predator, the southern elephant seal.From a five‐year simulation of prey biomass, we computed climatologies of mean prey biomass (average prey conditions) and prey biomass variability (meso‐scale variability). We also compiled spatially gridded metrics of seal density and diving behaviour from 13 yr of tracking data. We statistically modelled these metrics as non‐linear functions of prey biomass (both mean and variability) and used these to predict seal distribution and behaviour. Our predictions were consistent with observations (R2adj = 0.23), indicating that seals aggregate in regions of high mesoscale activity where eddies concentrate prey. Here, seals dived deeper (R2marg = 0.12, R2cond = 0.51) and spent less time hunting (R2marg = 0.05, R2cond = 0.56), likely targeting deep but profitable prey patches. Seals generally avoided areas of low eddy activity where prey was likely dispersed. Most seals foraged south of the Subantarctic Front, despite north of the front exhibiting consistently high simulated prey biomasses. This likely reflects seal prey or habitat preferences, but also emphasises the importance of mesoscale prey biomass variability relative to regionally high mean biomass. This work demonstrates the value of coupling mechanistic representations of prey biomass with predator observations to provide insight into how biophysical processes combine to shape species distributions. This will be increasingly important for the robust prediction of species’ responses to rapid system change.

Marine animals such as the southern elephant seal (Mirounga leonina) rely on a productive marine environment and are vulnerable to oceanic changes that can affect their reproduction and survival rates. Davis Base, Antarctica, acts as a moulting site for southern elephant seals that forage in Prydz Bay, but the genetic diversity and natal source populations of these seals has not been characterized. Determining the genetic diversity of moulting populations like this one provides essential information on seal dispersal, inter-population mixing, and foraging behaviours. In this study, we combined genetic and animal tracking data on these moulting seals to identify levels of genetic diversity, natal source population, and movement behaviours during foraging and haul-out periods. Using mitochondrial sequence data, we identified two major breeding lineages of seals at Davis Base. We found that the majority of the seals originated from breeding stocks within the South Atlantic Ocean and South Indian Ocean. One seal was grouped with the Macquarie Island breeding stock (South Pacific Ocean). The Macquarie Island population, unlike the other two stocks, is decreasing in size. Tracking data revealed long-distance foraging activity of the Macquarie Island seal around Crozet Islands. We speculate that changes to the Antarctic marine environment have resulted in a shift in foraging and dispersal strategies, which subsequently affects seal population growth rates. These findings have implications for conservation management plans aimed at improving the population status of the southern elephant seal.

International audience; The Patagonian slope is the region where Subantarctic waters and bathymetry give raise to physical and ecological processes that support a rich biodiversity and a large-scale industrial fisheries. Unique among the species that depend on this region is the deep diving southern elephant seal, Mirounga leonina. We report here on changes in the foraging behavior of a female seal explained by the combined effect of a cold and high salinity water mass and a decrease in surface chlorophyll-a concentration. Behavioral and oceanographic data from about 5000 profiles of temperature, conductivity, pressure, light and prey encounters were collected within an area ranging 59.5–61°W and 46–47.5°S, at depths of 300–700 m, on the Patagonian slope, during November–December 2018. A decrease in temperature (0.15 °C) and an increase in salinity (0.03) was found below the mixed layer, during December. Light data revealed a significant increase of irradiance in December (almost reaching the ocean bottom) associated with a decrease of chlorophyll-a in the upper levels. Concomitantly, the seal had a different diving behavior in December, foraging near the surface at night and close to the bottom during daylight hours. Also, the seal doubled the prey capture attempts in December compared to November. This study reveals the importance of ocean physical properties on seal's diving and foraging behavior, and how this changes, although small, can impact on seals diet and body composition during their post-breeding trips.

The southern elephant seal Mirounga leonina is the largest member of the phocid seals and is a highly sexually dimorphic predator at circumpolar regions. In this study, we generated the first high-quality de novo assembly of the blood transcriptome of M. leonina using the Illumina MiSeq platform. A total of 40.5 million raw reads were obtained and assembled using the Oases assembly platform, resulting in 46,445 contigs with an N50 value of 634 bp. We performed functional gene annotations through pathway analyses of the Gene Ontology (GO), Eukaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Ortholog comparison revealed that a high proportion of the M. leonina blood transcriptome had significant sequence homology within pinnipeds. M. leonine, a deep and long-diving seal, is routinely exposed to progressive hypoxia during dives. KEGG analyses detected an intact hypoxia-inducible factor-1 (HIF-1) signaling pathway, which is a key metabolism pathway in the adaptive homeostatic responses to hypoxia. In the blood transcriptome, many essential genes involved in innate immunity were detected, which suggests that the blood serves as a host defense modulator against exogenous infections in M. leonina. This genomic resource will be useful for understanding adaptive metabolism upon repeated breath-hold dives and determining the health status of southern elephant seals without the need to sacrifice them in experiments.

The overall study was funded by the IPEV (Program 1037 HEnergES), doctoral fellowships of French Ministry of Higher Education and Research, the University of St Andrews, the Marine Alliance for Science and Technology for Scotland (MASTS) and the Carnegie Trust for the Universities of Scotland. While endotherms can rely on their insulation to reduce heat loss to adapt to cold environments, renewing of fur during molt impairs insulation while they have to perfuse the periphery to support epidermal tissues. The southern elephant seal Mirounga leonina undertakes an annual catastrophic molt while fasting on land in a wet, windy and cold environment. However, southern elephant seals show characteristic aggregation patterns that are predicted to reduce high metabolic costs during the molt. Between 2012 and 2016, 59 female elephant seals were tracked on land during their molt to study their aggregation behavior in relation to molt stage, habitat type and local weather conditions. Infrared thermography and stomach temperature loggers were used to observe variation in body surface and internal temperature in relation to molt stage and aggregation behavior. We found that thermal constraints varied during the molt, with a peak in surface temperature during the mid-stage of the molt. Wallows (mud pools) appear as favorable habitat to aggregate while molting. Indeed, wallows offered a warmer microclimate with greater ground temperature and lower wind speed. Moreover, there was a greater proportion of aggregated seals and larger group size in wallows. These aggregation patterns in wallows were influenced by local weather such that a greater proportion of seals were located in the center of the aggregation, and larger group size occurred during days of unfavorable meteorological conditions. We also observed a higher proportion of seals at mid-stage of molt amongst aggregated seals compared to isolated individuals. This aggregation behavior may reduce the cost of thermogenesis as surface body temperature and stomach temperature were cooler by 1.0 °C and 1.5 °C, respectively, in aggregated compared to isolated seals. As a consequence, huddling behavior may be thermally advantageous for female southern elephant seals during the molt. Postprint

Behavioural contagion is a curious phenomenon of human social life which is believed to facilitate group living. It has also been demonstrated in animals that some behaviours may be contagious: how widespread this phenomenon is remains unclear, as only a few species have been tested. In this context, we examined whether three behaviours commonly exhibited by moulting southern elephant seals (Mirounga leonina): “sneezing”, scratching and yawning could be contagious. Using the randomization approach, we found this to be the case in general for all the behaviours, although the pattern was not that obvious or present at all for all the social groups. This indicates there is a potential for social contagion but the issue is complex. Despite limitations associated with observational study on small-size social groups, this is the first report of contagious behaviours in marine mammals and is to encourage further investigation.

Seals (Phocidae) undergo an annual cycle of moulting that implies hair regeneration, and in the case of southern elephant seals, it also involves the superficial strata of the epidermis. Therefore, surviving the moulting period is crucial for their obligate and permanent ectoparasites. Throughout evolutionary time, sucking lice (Echinophtiriidae) have developed morphological, behavioural and ecological adaptations to cope with the amphibious lifestyle of their hosts. Lepidophthirus macrorhini, the Southern elephant seal louse species, faces the additional challenge of surviving attached to the host during the moulting period. Since lice live on the skin, L. macrorhini has developed a unique survival strategy by piercing the skin of their host, thus keeping them protected from moulting. During fieldwork in Patagonia and Antarctica, skin samples with lice within were collected for histological analysis to assess whether these parasites caused damage to the host. Lice generate an inflammatory process in the host's dermis, and these lesions could alter the normal chemical and mechanical protective properties of the skin facilitating secondary infections. Further studies that analyse the potential pathogens in those skin lesions are necessary to properly assess the real impact of ectoparasites on their host health.

Intraspecific variation in animal mating systems can have important implications for ecological, evolutionary and demographic processes in wild populations. For example, patterns of mating can impact social structure, dispersal, effective population size and inbreeding. However, few species have been studied in sufficient detail to elucidate mating system plasticity and its dependence on ecological and demographic factors. Southern elephant seals (Mirounga leonina) have long been regarded as a textbook example of a polygynous mating system, with dominant ‘beachmaster’ males controlling harems of up to several hundred females. However, behavioural and genetic studies have uncovered appreciable geographic variation in the strength of polygyny among elephant seal populations. We therefore used molecular parentage analysis to investigate patterns of parentage in a small satellite colony of elephant seals at the South Shetland Islands. We hypothesised that dominant males would be able to successfully monopolise the relatively small numbers of females present in the colony, leading to relatively high levels of polygyny. A total of 424 individuals (comprising 33 adult males, 101 adult females and 290 pups) sampled over eight years were genotyped at 20 microsatellites and reproductive success was analysed by genetically assigning parents. Paternity could only be assigned to 31 out of 290 pups (10.7%), despite our panel of genetic markers being highly informative and the genotyping error rate being very low. The strength of inferred polygyny was weak in comparison to previous genetic studies of the same species, with the most successful male fathering only seven pups over the entire course of the study. Our results show that, even in a species long regarded as a model for extreme polygyny, male reproductive skew can vary substantially among populations.

Among the five seal species inhabiting the southern hemisphere and distributed around and south of the Antarctic Convergence, the southern elephant seal (Mirounga leonina, Pinnipedia, Phocidae) has the northernmost distribution, reaching sites surrounded by temperate waters. During the annual cycle, seals spend most of their time at sea, alternating with two highly synchronized shore-based haul-out periods for breeding and molting. On land, the distribution area is restricted to locations on islands or mainland, while at sea they travel distances of thousands of km2. In the global distribution, there are four genetically identified stocks; two are settled in Latin America (Georgias del Sur-South Georgia and Peninsula Valdes). In this chapter, we focus on the colonies of Argentina, Chile, and the Antarctic Peninsula that have resident animals for breeding and molting and from where tagged seal migration covers a wide latitudinal range from the equator to Antarctica. Long-term and systematic studies at the Peninsula Valdes colony facilitated the comparison with other colonies further south. Annual cycle, demographic, and foraging aspects are described in this chapter emphasizing migrations at sea and distribution. The chapter closes with a consideration of conservation status and threats.

Knowledge of the health status and potential effect of disease outbreaks among Southern Ocean fauna may be decisive for its conservation. We assessed the exposure and infection of Antarctic fur seals (Arctocephalus gazella, AFS) and Southern elephant seals (Mirounga leonine, SES) to parapoxvirus, Phocid alphaherpesvirus-1 (PhHV-1), smooth Brucella spp. and Toxoplasma gondii. AFS (n = 65) serum and swab samples, and SES (n = 13) serum samples from the sub--Antarctic island of Bouvetøya (54°25’S, 03°22’E) were collected during two austral summers (2014/15, 2017/18). Three polymerase chain reaction (PCR) tests amplifying the DNA polymerase, B2L and GIF parapoxvirus genomic regions were performed, investigating DNA from mucosal swab samples. The glycoprotein B gene was targeted to detect PhHV-1 viral DNA. Sera were assayed for T. gondii and smooth Brucella spp. antibodies with indirect enzyme-linked immunosorbent assays. Parapoxvirus PCR amplicons of the expected size were generated in two of the 29 AFS pups (nasal swabs, 2014/15), targeting the B2L (n = 2) and DNA polymerase (n = 1) genes, whereas the GIF PCR did not amplify target sequences. The PCR amplicons were sequenced and blasted in GenBank, revealing highest similarity with a seal parapoxvirus, confirming the presence of the virus in AFS for the first time. No PhHV-1 amplicons were generated, and antibodies against T. gondii or smooth Brucella spp. were not detected. Our data indicate that these seals are host for parapoxvirus but are neither exposed to smooth Brucella spp. nor T. gondii. Evidence of PhHV-1 shedding was not detected.

International audience; Identifying factors influencing survivorship is key to understanding population persistence. Although satellite telemetry is a powerful tool for studying remote animal ecology and behaviour it is rarely used for demographic studies because distinguishing the death of the animal (individual mortality) from failure of the tag (mechanical tag failure) has proven difficult. Southern elephant seals present an opportunity to separate tag failure from animal mortality thanks to the availability of large tracking datasets, broad knowledge of demographic rates, and because for these large animals, satellite tags are known not to influence mortality rates. A key rationale for investigating satellite telemetry to estimate mortality as compared to using traditional Capture-Mark-Recapture methods is the potential for obtaining spatially and temporally specific information, particularly while the animals are at sea and largely unobservable. We used satellite tag data from 182 seals from Isles Kerguelen, deployed between 2004 and 2018. Of these, 76 (42%) tags transmitted for the full post-moult foraging trip (max. 265 days for females and max. 305 days for sub-adult males) with the remaining 107 tags (58%) ceasing transmission at sea. We found that contrary to expectations, behavioural choices seem not to influence tag failure rates by mechanical means, rather the signals we detected seemed to align with previously described variation in mortality between groups. There was evidence, albeit limited, for an increase in tag failure for adult females in years with negative Southern Annular Mode (lower Southern Ocean productivity). We speculate that this increase in failure may suggest higher mortality in these years. Also, males using the Kerguelen Plateau had higher tag failure rates than those in the sea-ice zone, perhaps indicative of higher mortality. We suspect that these differences in tag failure rates between groups reflect variation in predator exposure and foraging success. This suggests satellite telemetry could be used to infer mortality events for southern elephant seals while they are at sea.

Records of southern elephant seals (Mirounga leonina) as vagrants along the SE Brazilian coast date back the late 50’s and have been relatively common over the last decades. These large marine mammals usually call much attention when they arrive on tropical beaches worldwide and are generally treated as ‘occasional visitors’ and ‘vagrants’. This note reports on sightings of a young elephant seal along SE Brazil in the summer and autumn of 2020. We also reviewed records in both the literature and open sources, totaling eight records of infant southern elephant seals known since the late 70’s along the Brazilian coast. It was noted that the arrival of an infant in February of 2020 is coincident with a previous cyclonic activity off the SE and NE Brazilian coast. The connection of such unlikely records of pinnipeds on tropical beaches and extreme weather events associated to ocean currents should be better evaluated in the context of climatic change RESUMO E reportada uma ocorrencia recente de um infante de elefante-marinho ( Mirounga leonina ) na costa do estado do Rio de Janeiro com um intervalo aproximado de um mes entre as avistagens do mesmo individuo. A comparacao das fotografias obtidas em ambos os registros permitiu a comparacao e confirmacao. Em adicao, se discute a presenca de infantes na costa brasileira, que totalizam oito casos, mas que nao apontam uma sazonalidade marcada, mas uma tendencia aos registros serem reportados em junho, seguido por outubro e novembro. Como o presente registro se deu em janeiro, pico do verao, fatores climaticos de larga escala podem estar atuando para deslocar alguns individuos muito ao longe das suas colonias. Palavras-chave: Mirounga leonina; Movimentos; Vagante; Atlântico Sul.

[Figure][1] A female elephant seal equipped with two data-logging tags. Photo credit: Martin Ignacio Brogger. After weeks marooned on beaches nursing their pups, southern elephant seal mothers have only one thing on their mind: getting back into the ocean to feast on lantern fish and

Bioluminescence, which occurs in approximately 80% of the world's mesopelagic fauna, can take the form of a low-intensity continuous glow (e.g. for counter-illumination or signalling) or fast repetitions of brighter anti-predatory flashes. The southern elephant seal (SES) is a major consumer of mesopelagic organisms, in particular the abundant myctophid fish, yet the fine-scale relationship between this predator's foraging behaviour and bioluminescent prey remains poorly understood. We hypothesised that brief, intense light emissions should be closely connected with prey strikes when the seal is targeting bioluminescent prey that reacts by emitting anti-predator flashes. To test this, we developed a biologging device containing a fast-sampling light sensor together with location and movement sensors to measure simultaneously anti-predator bioluminescent emissions and the predator's attack motions with a 20 ms resolution. Tags were deployed on female SES breeding at Kerguelen Islands and Península Valdés, Argentina. In situ light levels in combination with duration of prey capture attempts indicated that seals were targeting a variety of prey types. For some individuals, bioluminescent flashes occurred in a large proportion of prey strikes, with the timing of flashes closely connected with the predator's attack motion, suggestive of anti-predator emissions. Marked differences across individuals and location indicate that SES do exploit bioluminescent organisms but the proportion of these in the diet varies widely with location. The combination of wideband light and acceleration data provides new insight into where and when different prey types are encountered and how effectively they might be captured., Highlighted Article: Description of a new measurement method and its successful application to deep-diving elephant seals, showing that these predators attempt to catch mesopelagic prey that react with bright anti-predator flashes.

The southern elephant seal Mirounga leonina is the largest phocid seal and one of the two species of elephant seals. They are listed as &lsquo, least concern&rsquo, by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species 2015. Here, we have assembled the reference genome for M. leonina using the 10&times, chromium sequencing platform. The final genome assembly of M. leonina was 2.42 Gb long, with a contig N50 length of 54 Mb and a maximum length of 111.6 Mb. The M. leonina genome contained 20,457 predicted protein-coding genes and possessed 41.51% repeated sequences. The completeness of the M. leonina genome was evaluated using benchmarking universal single-copy orthologous genes (BUSCOs): the assembly was highly complete, containing 95.6% of the core set of mammalian genes. The high-quality genomic information on M. leonina will be essential for further understanding of adaptive metabolism upon repeated breath-hold dives and the exploration of molecular mechanisms contributing to its unique biochemical and physiological characteristics. The southern elephant seal genome project was deposited at NCBI (National Center for Biotechnology Information) under BioProject number PRJNA587380.

The southern elephant seal Mirounga leonina is the largest phocid seal and one of the two species of elephant seals. They are listed as ‘least concern’ by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species 2015. Here, we have assembled the reference genome for M. leonina using the 10× chromium sequencing platform. The final genome assembly of M. leonina was 2.42 Gb long, with a contig N50 length of 54 Mb and a maximum length of 111.6 Mb. The M. leonina genome contained 20,457 predicted protein-coding genes and possessed 41.51% repeated sequences. The completeness of the M. leonina genome was evaluated using benchmarking universal single-copy orthologous genes (BUSCOs): the assembly was highly complete, containing 95.6% of the core set of mammalian genes. The high-quality genomic information on M. leonina will be essential for further understanding of adaptive metabolism upon repeated breath-hold dives and the exploration of molecular mechanisms contributing to its unique biochemical and physiological characteristics. The southern elephant seal genome project was deposited at NCBI (National Center for Biotechnology Information) under BioProject number PRJNA587380.

Southern elephant seal (SES) and Antarctic fur seal (AFS) are short Southern Ocean food web top predators and are spatial and temporal trend bioindicators of Antarctic Hg bioavailability. Hg, stable isotope composition (δ 13C and δ 15N) and trophic position (TP) regarding sex were determined using lanugo samples from Antarctic pinnipeds pups (SES n = 35 and AFS n = 11). Hg concentrations in over 50% of the SES pups (mean 5.9 ± 3.1 mg kg−1 dry wt.) are compatible with those found to cause neurologic damage to polar bears in the Arctic. No significant differences regarding sexes for SES or AFS are found based on mean Hg concentrations normalized by body weight. δ 15N values and TPs are similar among both species, indicating that gestating SES and AFS mothers feed at the same trophic level. Significantly different δ 13C values were found, indicating distinct feeding grounds for mothers belonging to both species when pup lanugo is formed in utero; while SES females like to feed in Antarctic waters, AFS females remain in sub-Antarctic waters. The differences in Hg and δ 13C observed for both species reflect not only contrasting feeding habits and anthropogenic Hg inputs, but also maternal foraging strategies.

The southern elephant seal (SES), Mirounga leonina, has an estimated abundance of 900,000 individuals and a nearly circumpolar distribution in the Southern Hemisphere. In Chile, the species inhabits three colonies in the Magallanes Region (54°24′S) and the northernmost sightings have been attributed to vagrant individuals. The aim of this study is to reassess the distribution of SES on the Pacific Coast. Censuses were conducted from 2004 to 2017, from 29°02′S to 29°16′S and from 38°22′S to 48°23′S. Data from social media and official landing records were also incorporated to complement the research sightings. A total of 72 SES were sighted in 40 haul-out sites; 42% of the animals were found in haul-out sites shared with the South American sea lion, 4% in wetland haul-out sites, and 54% in other haul-out sites. We recorded a parturition event in the Dallico wetland, at latitude 42°19′S, which establishes the northernmost location of breeding SES in the Pacific Coast. Our data show an increase in the number of adult and immature SESs sighted in middle latitudes during survey years with similar sampling effort (2007–2016). Interestingly, we corroborated the sighting of an adult female for 9 years in the Marine Protected Area Isla Chanaral (29°02′S), evidencing long-term fidelity to foraging regions in nonbreeding ranges of the species. The high productivity in the distribution area, where isolated and protected areas are located, makes these ideal places to find new foraging and resting grounds at middle–low latitude hotspots.

A photogrammetric flight was performed in December 2016 as BVLOS (Beyond Visual Line of Sight) operation over Penguin Island (South Shetland Islands, Western Antarctica). Images were taken by the PW-ZOOM fixed-wing UAV equipped with a digital SLR Canon 700D camera. The flight was performed at 550 m ASL and covered a total distance of 231.58 km. The plane take-off and landing site was near the H. Arctowski Polish Antarctic Station (Arctowski) on King George Island, South Shetlands. The main aim of the mission was to collect environmental data to estimate the size of penguin and pinniped breeding populations and to map vegetation cover and landforms. The plane returned to Arctowski with 1630 images of Penguin Island with the ground sample distance (GSD) lower than 0.07 m. The analysis of developed ortophoto allowed us to locate and identify individuals of two penguin species (Adelie and chinstrap), and individuals of two species of pinnipeds (Southern elephant seal and Weddell seal). Three types of tundra communities were mapped together with numerous landforms such as: volcanic, mass movement, fluvial, coastal and aeolian ones. The UAV BVLOS photogrammetric operation proved to be very robust in gathering valuable qualitative and quantitative data necessary for monitoring distant and isolated polar environments.

High juvenile mortality rates are typical of many long‐lived marine vertebrate predators. Insufficient development in dive and forage ability is considered a key driver of this. However, direct links to survival outcome are sparse, particularly in free‐ranging marine animals that may not return to land.In this study, we conduct exploratory investigations toward early mortality in juvenile southern elephant seals Mirounga leonina. Twenty postweaning pups were equipped with (a) a new‐generation satellite relay data tag, capable of remotely transmitting fine‐scale behavioral movements from accelerometers, and (b) a location transmitting only tag (so that mortality events could be distinguished from device failures). Individuals were followed during their first trip at sea (until mortality or return to land). Two analyses were conducted. First, the behavioral movements and encountered environmental conditions of nonsurviving pups were individually compared to temporally concurrent observations from grouped survivors. Second, common causes of mortality were investigated using Cox's proportional hazard regression and penalized shrinkage techniques.Nine individuals died (two females and seven males) and 11 survived (eight females and three males). All but one individual died before the return phase of their first trip at sea, and all but one were negatively buoyant. Causes of death were variable, although common factors included increased horizontal travel speeds and distances, decreased development in dive and forage ability, and habitat type visited (lower sea surface temperatures and decreased total [eddy] kinetic energy).For long‐lived marine vertebrate predators, such as the southern elephant seal, the first few months of life following independence represent a critical period, when small deviations in behavior from the norm appear sufficient to increase mortality risk. Survival rates may subsequently be particularly vulnerable to changes in climate and environment, which will have concomitant consequences on the demography and dynamics of populations., High juvenile mortality rates are typical of many long‐lived marine predators and are likely linked to insufficient development of dive and forage ability. Here, we investigate such processes in juvenile southern elephant seals using a new generation of bio‐logging tags, capable of remotely transmitting behavioral information through the Argos satellite system. We found that causes of early mortality during the first year of life were linked to decreased development in dive and forage ability alongside a failure to locate suitable foraging habitat.

Background: Extralimital observations of pinnipeds are important to understand the effects of changing climates on our oceans and the distribution of these species. The southern elephant seal (Mirounga leonina) is a known vagrant species that moves over long distances. We report three new records of M. leonina in interior freshwater tributaries of the Guayas River Estuary Basin (Gulf of Guayaquil) and northern coast of Ecuador between October 2017 and January 2018 during a cold episode of La Nina event in the southeastern Pacific. Results: The elephant seals were identified according to their large size (~ 5 m for adult and 2–3 m for juveniles/subadults), the head to neck size ratio, and the size and external morphology of the proboscis, which was used as a key trait to differentiate M. leonina from the Northern elephant seal (M. angustirostris). The observations of M. leonina in Ecuador highlight an extreme movement covering an assumed total distance of approximately 8000 km from the circumpolar region. The cold event “La Niña” with sea surface temperature anomalies ranging − 1.5 °C to − 0.5 °C in October 2017 likely triggered the extralimital movements of these animals. Conclusion: Recurring observations of M. leonina in the Guayaquil Gulf suggest the importance of this highly productive region and tropical estuarine-riverine habitats as temporary haulout sites for resting. These new findings indicate that vagrant individuals influenced by oceanographic events and eco-physiological processes are reaching this region more frequently than previously thought.

We report four years (2012-2015) of consecutive observations of the same juvenile male Southern elephant seal along the coast Espírito Santo (ES), Brazil, identified based on scars of cookiecutter shark bites. In 2015 three bacteries were isolated from a recent lesion using routine methods of bacterial culture and identification, and a large number of barnacles were seen attached to the fur of other body regions, especially on the pelvic limbs and lower back. We collected 12 barnacles from different body areas, and identified all of them as Eared barnacles (Conchoderma aurita). Additionally, a sample of feces was obtained and analyzed through simple-flotation, revealing helminth eggs compatible with Contracaecum sp.

Biologging technologies are changing the way in which the marine environment is observed and monitored. However, because device retrieval is typically required to access the high‐resolution data they collect, their use is generally restricted to those animals that predictably return to land. Data abstraction and transmission techniques aim to address this, although currently these are limited in scope and do not incorporate, for example, acceleration measurements which can quantify animal behaviours and movement patterns over fine‐scales.In this study, we present a new method for the collection, abstraction and transmission of accelerometer data from free‐ranging marine predators via the Argos satellite system. We test run the technique on 20 juvenile southern elephant seals Mirounga leonina from the Kerguelen Islands during their first months at sea following weaning. Using retrieved archival data from nine individuals that returned to the colony, we compare and validate abstracted transmissions against outputs from established accelerometer processing procedures.Abstracted transmissions included estimates, across five segments of a dive profile, of time spent in prey catch attempt (PrCA) behaviours, swimming effort and pitch. These were then summarised and compared to archival outputs across three dive phases: descent, bottom and ascent. Correlations between the two datasets were variable but generally good (dependent on dive phase, marginal R 2 values of between .45 and .6 to >.9) and consistent between individuals. Transmitted estimates of PrCA behaviours and swimming effort were positively biased to those from archival processing.Data from this study represent some of the first remotely transmitted quantifications from accelerometers. The methods presented and analysed can be used to provide novel insight towards the behaviours and movements of free‐ranging marine predators, such as juvenile southern elephant seals, from whom logger retrieval is challenging. Future applications could however benefit from some adaption, particularly to reduce positive bias in transmitted PrCA behaviours and swimming effort, for which this study provides useful insight.

Mesoplodont beaked whales are extreme divers, diving for over 45 mins and to depths of over 800 m. These dives are of similar depth and duration to those of the giant sperm whale (Physeter macrocephalus) whose body mass can be 50 times larger. Velten et al. (2013) provided anatomical data that demonstrated that on-board oxygen stores were sufficient to aerobically support the extreme dives of mesoplodonts if their diving metabolic rates are low. Because no physiological data yet exist, we utilized an anatomical approach-the body composition technique-to examine the relative metabolic rates of mesoplodonts. We utilized a systematic mass dissection protocol to compare the body composition of mesoplodonts with those of two short duration, shallow divers-the harbor porpoise (Phocoena phocoena) and bottlenose dolphin (Tursiops truncatus). We then investigated the body composition of two other extreme divers, the southern elephant seal (Mirounga leonina) and P. macrocephalus using data from the literature. Our results demonstrate that extreme divers invest a smaller percentage of their total body mass (TBM) in metabolically expensive brain and viscera, and a larger percent of their TBM in inexpensive integument, bone, and muscle, than do the shallow divers. Deep divers also share features of their locomotor muscle that contribute to relatively low tissue metabolic rates and high oxygen storage capacity, including large muscle fiber diameters, low mitochondrial volume densities, and high myoglobin concentrations. One feature of the locomotor muscle of mesoplodonts, though, is unique among deep divers investigated to date. Rather than having an endurance athlete's muscle fiber profile, dominated by slow oxidative fibers, mesoplodonts possess a sprinter's profile, dominated by fast glycolytic fibers. Velten et al. (2013) hypothesized that these fibers are likely inactive during routine swimming and provide a large, metabolically inexpensive oxygen store for the slow oxidative fibers to aerobically power swimming. We suggest that future anatomical analyses, coupled with performance data transduced through tagging studies, will enhance our understanding of the extreme diving capabilities of marine mammals.

Life history trade-off theory predicts that current reproduction can negatively affect survival and future reproduction. Few studies have assessed breeding costs for males of polygynous species compared to females, despite substantial variation in breeding success among individual males (e.g. subordinate cf. dominant breeders). Specifically, differentiating between the cost of attending breeding seasons, and the additional cost of successfully securing and mating females is lacking. We investigated whether trade-offs are present in the highly polygynous male southern elephant seal (Mirounga leonina) using 34-years of individual-level data. We compare age-specific survival, recruitment and future breeding success probabilities of pre-breeders (males yet to recruit) and breeders (subordinate and dominant social ranks) using multievent models. Pre-breeders and breeders of overlapping ages had similar survival probabilities, suggesting that there was no attendance cost for early recruits. In addition, the probability of recruiting as a dominant breeder never exceeded recruitment probability as a subordinate breeder of the same age. Therefore, older pre-breeders that delayed attendance costs generally did not improve their breeding success (probability of being dominant) at recruitment more than younger recruits. Rather, recruitment age may be a function of individual quality, with lower quality individuals requiring more time to socially mature. When comparing subordinate and dominant breeders, we found clear evidence for survival senescence, with subordinate breeders having a higher baseline mortality. In contrast, age-specific future breeding success (probability of being dominant at t + 1) increased with age, with dominant breeders maintaining higher subsequent breeding success than subordinate breeders. The opposite trends in survival and future breeding success for both subordinate and dominant breeders may indicate a lifetime, population-level trade-off. However, we found no evidence to suggest that being a dominant breeder consecutively (and having a higher accumulated breeding cost) accelerated the rate of senescence when compared to individuals that were previously subordinate. Thus, males experienced actuarial senescence regardless of social rank, with dominant (and possibly high quality) breeders showing a reduced trade-off between survival and future breeding success. We make several novel contributions to understanding polygynous male life histories and southern elephant seal demography.

In this Opinion, adaptations to hypoxia are examined during the short time domains of breath holds from three accomplished diving animals: northern elephant seals (Mirounga angustirostris), California sea lions (Zalophus californianus), and emperor penguins (Aptenodytes forsteri). Review of dive behavior, oxygen (O2) storage, and arterial blood O2 profiles during dives reveals that the elephant seal undergoes the most frequent and extreme hypoxemia. Exceptional breath hold durations, routine hypoxemia, established research protocols, and accessibility to the animals make the elephant seal stand out for physiological investigation and evaluation of biochemical/molecular adaptations in hypoxemic tolerance, protection against re-perfusion injury, and O2 transport during dives. The northern elephant seal and southern elephant seal (M. leonina) are the premier pinniped divers (Le Boeuf et al., 1988; Hindell et al., 1991, 1992; Hassrick et al., 2010; Robinson et al., 2012). During several month-long trips to sea, these animals spend 80–90% of their time underwater, perform routine dives of 20–30 min duration to average depths >400 m, have short inter-dive surface intervals that average two min, and typically gain about one kg d−1 in body mass. In contrast to elephant seals, California sea lions only spend about 30% of their time at sea diving (Feldkamp et al., 1989). Most dives are < 100 m in depth and between 1 and 4 min in duration (McDonald and Ponganis, 2013; Tift et al., 2017). However, dependent on geographic location, climate variability, and prey distribution, these sea lions can regularly perform 10-min dives to 400–500 m, with the current longest reported dive of 16 min (Melin et al., 2008; McHuron et al., 2016, 2018). Emperor penguins are the premier avian divers; they exploit the entire water column to depths >500 m. Shallower dives are up to 5–6 min in duration while deep dives are about 10 min (Kooyman and Kooyman, 1995; Kirkwood and Robertson, 1997; Sato et al., 2011). The longest dive documented by a continuous dive profile in an emperor penguin is 27.6 min. During foraging trips to sea, emperor penguins spent about 31% of their time resting on the sea ice (Watanabe et al., 2012).

Development of the sonar was supported by a Semper Ardens grant from the Carlsberg Foundation (PI PT Madsen) and from the CNES-TOSCA program (elephant seals as bio-samplers of biological fields in relation to in situ oceanographic conditions (PI C Guinet). Fieldwork in Kerguelen was supported by the French Polar Institute as part of the Cycle Eleph Programme (N° 1201, PI. C Gilbert). PG was supported by the Next Generation Unmanned Systems Science (NEXUSS), a National Environmental Research Council doctoral training programme, and the Marine Alliance for Science and Technology Scotland (MASTS). MJ was supported by a Marie Curie Sklodowska Career Integration Grant, by MASTS, and by a visiting Professor scholarship at Aarhus University. How predators find, select and capture prey is central to understanding trophic cascades and ecosystem structure. But despite advances in biologging technology, obtaining in situ observations of organisms and their interactions remains challenging in the marine environment. For some species of toothed whales, echoes from organisms insonified by echolocation clicks and recorded by sound logging tags have provided a fine-scale view of prey density, and predator and prey behaviour during capture attempts, but such information is not available for marine predators that do not echolocate. Here the development and performance of a miniature biomimetic sonar and movement tag capable of acquiring similar data from non-echolocating marine predators is reported. The tag, weighing 200 g in air, records wide bandwidth sonar data at up to 50 pings a second synchronously with fast-sampling sensors for depth, acceleration, magnetic field and GPS. This sensor suite enables biotic conditions and predator behaviour to be related to geographic location over long-duration foraging trips by apex marine predators. The sonar operates at 1.5 MHz with a 3.4° beamwidth and a source level of 190 dB re 1 μPa at 1 m. Sonar recordings from a trial deployment of the tag on a southern elephant seal contained frequent targets corresponding to small organisms up to 6 m ahead of the tagged animal. Synchronously sampled movement data allowed interpretation of whether the seal attempted to capture organisms that it approached closely while the high sonar ping rate revealed attempts by prey to escape. Results from this trial demonstrate the ability of the tag to quantify the biotic environment and to track individual prey captures, providing fine-scale information on predator-prey interactions which has been difficult to obtain from non-echolocating marine animals. Postprint

The area west of the Kerguelen Islands (20–70°E/45–60°S) is characterized by a weak mesoscale activity except for a standing meander region of the Antarctic Circumpolar Current (ACC) localized between 20 and 40°E. A unique bio-physical dataset at high-resolution collected by a southern elephant seal (Mirounga leonina) reveals a conspicuous increase in foraging activity at the standing meander site up to 5 times larger than during the rest of her three-month trip west of the Kerguelen Islands. Here, we propose a physical explanation for such high biological activity based on the study of small-scale fronts with scales of 5 to 20 km, also called submesoscales. The standing meander is associated with intensified frontal dynamics at submesoscale, not observed in the rest of the region. Results shed new light on the spatial distribution of submesoscale fronts in the under-sampled area west of the Kerguelen plateau and emphasize their importance for upper trophic levels. Despite that most elephant seals target foraging grounds east of the Kerguelen Plateau, our findings suggest that excursions to the west are not accidental, and may be explained by the recurrently elevated physical and biological activity of the site. As such, other standing meanders of the ACC may also act as biological hotspots where trophic interactions are stimulated by submesoscale turbulence.

Eight PBDE congeners, three emerging brominated flame retardants, five dechloranes and eight MeO-PBDEs were monitored in tissues (muscular, adipose, brain) and fur of southern elephant seal and Antarctic fur seal of the South Shetland Islands, Antarctic Peninsula. Total PBDEs and total dechloranes concentrations ranged between n.d.–6 ng/g lw. While PBDEs were not detected in brain tissue, Dec 602 was found in brain tissue of both seal species indicating that dechloranes —with potential neurological toxicity— could cross the blood-brain barrier. Emerging brominated flame retardants were not detected in any sample and only two MeO-PBDEs, which are of natural origin, were found. The presence of the detected compounds in biota from the Antarctic evidences their long-range transportation, being of special interest the detection of emerging compounds such as dechloranes. This is the first time that these contaminants have been detected in marine mammals from the Antarctic. BDE-47 concentrations were lower than previously reported for the same species, suggesting a successful effect of the existing regulation and bans on PBDEs. Capsule abstract: Halogenated flame retardants were in tissues of Antarctic seals proving long-range transport. Dechloranes showed similar behaviour to PBDEs, additionally they crossed the BBB. © 2018 Elsevier B.V., This work has been financially supported by the Generalitat de Catalunya (Consolidated Research Group 2017 SGR 01404 – Water and Soil Quality Unit). Biotage is acknowledged for providing SPE cartridges. The samples were collected with support of the Brazilian Antarctic Program (PROANTAR). The authors would like to thank the logistic support by Brazilian Navy and Aeronautics Forces. Project CNPq number (ESC). MBA has sandwich doctorate fellowship by CNPq – PDEE.

The Southern elephant seal (SES) is a marine species that can be found at sea throughout the Southern Ocean on most sub-Antarctic islands. An unusual record of a solitary Southern elephant seal (Mirounga leonina) in freshwater habitat is reported. The seal was found 16 km upstream from the mouth of the Toltén River, in southern Chile (39°9’S; 73°10’W). The individual was classified as a sub-adult male approximately 3 m in length. Potential causes for the unusual presence of the seal in a river include feeding on native estuarine fishes and non-native Chinook salmon or resting. Long lasting resting (5 days) in the Toltén River by the seal may indicate suitable habitat and/or lack of disturbance.

The Southern elephant seal (SES) is a marine species that can be found at sea throughout the Southern Ocean on most sub-Antarctic islands. An unusual record of a solitary Southern elephant seal (Mirounga leonina) in freshwater habitat is reported. The seal was found 16 km upstream from the mouth of the Toltén River, in southern Chile (39°9’S; 73°10’W). The individual was classified as a sub-adult male approximately 3 m in length. Potential causes for the unusual presence of the seal in a river include feeding on native estuarine fishes and non-native Chinook salmon or resting. Long lasting resting (5 days) in the Toltén River by the seal may indicate suitable habitat and/or lack of disturbance.

Marine mammals found at the top of the trophic pyramid are excellent bioindicators of pollutants in the marine environment, the concentrations of which increase along with the trophic level of the organism. As these animals are usually protected species, their contamination has to be assessed non-invasively by analysing excrement and epidermal structures such as fur or claws. The present study involved testing the excrement and fur of the grey seal (Halichoerus grypus) from the Southern Baltic coast and the Southern elephant seal (Mirounga leonine) from Admiralty Bay, along with fish muscle (food) and the lithological background of both areas, for the presence of rare earth elements (REE). The soil on the Baltic coast is characterized by the predomination of light rare earth elements (LREE): yttrium, lanthanum and cerium (∑REE = 7.86 mg·kg−1 dw). In the soil and bedrock of Admiralty Bay all REEs were found except for terbium, thulium and lutetium (∑REE = 96.1 mg·kg−1 dw). The REE levels found in the muscles of Baltic herring (∑REE = 0.057 mg·kg−1 ww) were lower than those in the muscles of marbled rockcod (∑REE = 0.540 mg·kg−1 ww). The situation was analogous in the mammals, with the REE concentrations in grey seal fur (∑REE = 0.489 mg·kg−1 dw) and excrement (∑REE = 0.676 mg·kg−1 dw) being lower than those found in the fur (∑REE = 10.1 mg·kg−1 dw) and excrement (∑REE = 83.6 mg·kg−1 dw) of the elephant seal. The LREE/HREE partition coefficients in the grey seal excrement (3.37) and its fur (4.00), but also in the faeces of the elephant seal (2.63) and its fur (2.65), indicate that in each species the process of elimination from the body occurs in similar proportions.

Our study makes use of a fortuitous oceanographic data set collected around the remote sub-Antarctic island of Bouvetoya by a conductivity–temperature–depth recorder (CTD) integrated with a satellite-relayed data logger deployed on an adult female southern elephant seal ( Mirounga leonina ) to describe the seasonal evolution of the western shelf waters. The instrumented seal remained in waters over the shelf for 259 days, collecting an average of 2.6 (±0.06) CTD profiles per day, providing hydrographic data encompassing the late austral summer and the entire winter. These data document the thermal stratification of the upper water layer due to summer surface heating of the previous year’s Antarctic Surface Water, giving way to a cold subsurface layer at about 100 m as the austral winter progressed, with a concomitant increase in salinity of the upper layer. Upper Circumpolar Deep Water was detected at a depth of approximately 200 m along the western shelf of Bouvetoya throughout the year. These oceanographic data represent the only seasonal time series for this region and the second such animal–instrument oceanographic time series in the sub-Antarctic domain of the Southern Ocean. Keywords: Biotelemetry; diving; elephant seal; oceanography; marine predators; CTD-SRDL. (Published: 27 October 2016) To access the supplementary material for this article, please see supplementary files in the column to the right (under Article Tools). Citation: Polar Research 2016, 35 , 28278, http://dx.doi.org/10.3402/polar.v35.28278

During the 2019 breeding season (October-December), a battery-powered DIJ Inspire 2 drone was used to investigate a breeding southern elephant seal colony located at Patelnia Point (ASPA 128, King George Island, South Shetland Islands, maritime Antarctica). Twelve unmanned aerial vehicle (UAV) missions conducted 50–70 m above ground level (AGL) were completed to monitor the breeding ground with a maximum of 0.348 km2. The missions were planned in Pix4D Capture software. A drone, with the support of ground cameras and observations, was used to derive population counts, map harems, and track the phenology of the southern elephant seals. Based on data obtained from the UAV missions, orthophotomaps were created in PIX4D Mapper and then analyzed in QGIS. Calculated values of body size parameters such as body length and orthogonal body surface area were used to determine the age and sex of individuals. Analysis of the ranges of the harems on particular days, supported by an analysis of land conditions that generate physical barriers to the movement of animals, allowed zones in which the transformations of groups of harems took place to be determined. The hypothesized hermeticity of the designated zones was supported by statistical tests. The use of drones allows for comprehensive population analyses of the breeding colonies of elephant seals such as censuses of pups and adult individuals, determination of the sex ratio, and spatial analysis of the distribution of breeding formations. In addition, it allows for a more accurate result than ground counting.

Obtaining longitudinal endocrinological data from free-ranging animals remains challenging. Steroid hormones can be extracted sequentially from non-invasively sampled biologically inert keratinous tissues, such as feathers, nails, hair and whiskers. However, uncertainty regarding the type and levels of steroids incorporated into such tissues complicates their utility in wildlife studies. Here, we developed a novel, comprehensive method to analyze fourteen C19 and fourteen C21 steroids deposited chronologically along the length of seal whiskers in a single, 6-minute chromatographic step, using ultra-performance convergence chromatography-tandem mass spectrometry. The limits of detection and quantification ranged from 0.01 to 2 ng/mL and from 0.1 to 10 ng/mL, respectively. The accuracy and precision were within acceptable limits for steroids at concentrations ≥2 ng/mL. The recovery (mean = 107.5% at 200 ng/mL), matrix effect and process efficiency of steroids evaluated, using blanked whisker matrix samples, were acceptable. The method was applied to the analysis of steroid hormone levels in adult female whisker segments obtained from southern elephant seals (Mirounga leonina), n = 10, and two fur seal species, Antarctic fur seals (Arctocephalus gazella; n = 5) and subantarctic fur seals (Arctocephalus tropicalis; n = 5), sampled between 2012 and 2017. In the whisker subsamples analyzed (n = 71), the median concentration of steroid hormones detected above the LOQ ranged from 2.0 to 273.7 pg/mg. This was the first extraction of multiple C19 and C21 steroids, including their C11-oxy metabolites, from the whiskers of mammals. Measuring hormones sequentially along the whisker lengths can contribute to our understanding of the impact of stress associated with environmental/climate changes that affect the health, survival of organisms, as well as to delineate the reproductive cycles of free-living mammals with cryptic life stages.

Intermittent breeding by which organisms skip some current reproductive opportunities in order to enhance future reproductive success is a common life history trade‐off among long‐lived, iteroparous species. The southern elephant seal Mirounga leonina engages in intermediate breeding when body condition is low. While it is anticipated that this strategy may increase the lifetime reproductive output of this species, the conditions under which reproductive skipping are predicted to occur are not clear. Here I develop a dynamic state variable model based on published data that examines when southern elephant seals are predicted to optimally skip reproduction in order to maximize lifetime reproductive output as a function of current body mass, maternal age, and survivorship. I demonstrate that the optimal reproductive strategy for this species can include reproductive skipping, and that the conditions where this is optimal depend on patterns of mass‐dependent adult female survival. I further show that intermittent breeding can increase lifetime reproductive output, and that the magnitude of this benefit increases with the ability of individual animals to replenish depleted body mass through foraging. Finally, I show that when the environment is variable and foraging is reduced in bad years, the benefit of adopting an optimal strategy that includes reproductive skipping increases asymptotically with the frequency of bad years. These results highlight the importance of characterizing the pattern of adult survival in this species, as well as the need to identify other factors that may influence the prevalence and benefits of reproductive skipping.

Like many species, movement patterns of southern elephant seals (Mirounga leonina) are being influenced by long-term environmental change. These seals migrate up to 4000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among individuals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast-estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among-individual variability in southern elephant seal environment-movement relationships. We found that seals making foraging trips to the sea-ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea ice coverage and had variable responses to chlorophyllaconcentration, whereas seals that foraged pelagically reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, pelagic foragers may encounter more productive habitat but sea-ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat use.