Chemical threats for the sentinel Pygoscelis adeliae from the Ross Sea (Antarctica): Occurrence and levels of persistent organic pollutants (POPs), perfluoroalkyl substances (PFAS) and mercury within the largest marine protected area worldwide.

The Ross Sea Marine Protected Area (RS-MPA) hosts endemic species that have to cope with multiple threats, including chemical contamination. Adèlie penguin is considered a good sentinel species for monitoring pollutants. Here, 23 unhatched eggs, collected from three colonies along the Ross Sea coasts, were analysed to provide updated results on legacy pollutants and establish a baseline for newer ones. Average sum of polychlorinated biphenyls (∑PCBs) at the three colonies ranged 20.9-24.3 ng/g lipid weight (lw) and included PCBs IUPAC nos. 28, 118, 153, 138, 180. PCBs were dominated by hexachlorinated congeners as previously reported. Hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) ranged between 134 and 166 and 181-228 ng/g lw, respectively. Overall, ∑PCBs was exceeded by pesticides, contrary to previous studies from the Ross Sea. Sum of polybrominated diphenyl ethers (∑PBDEs) ranged between 0.90 and 1.18 ng/g lw and consisted of BDE-47 (that prevailed as expected, representing 60-80 % of the ∑PBDEs) and BDE-85. Sum of perfluoroalkyl substances (∑PFAS) ranged from 1.04 to 1.53 ng/g wet weight and comprised five long-chain perfluorinated carboxylic acids (PFCAs), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorooctanoic acid (PFOA); perfluorooctane sulfonamide (PFOSA) was also detected. The PFAS profile was dominated by PFCAs as already observed in Arctic seabirds. Mercury ranged from 0.07 to 0.15 mg/kg dry weight similarly to previous studies. Legacy pollutants confirmed their ongoing presence in Antarctic biota and their levels seemed mostly in line with the past, but with minor variations in some cases, likely due to continued input or release from past reservoirs. PFAS were reported for the first time in penguins from the Ross Sea, highlighting their ubiquity. Although further studies would be useful to increase the sample size and accordingly improve our knowledge on spatial and temporal trends, this study provides interesting data for future monitoring programs within the RS-MPA that will be crucial to test its effectiveness against human impacts.

Bottom-up effects drive the dynamic of an Antarctic seabird predator-prey system.

Understanding how populations respond to variability in environmental conditions and interspecific interactions is one of the biggest challenges of population ecology, particularly in the context of global change. Although many studies have investigated population responses to climate change, very few have explicitly integrated interspecific relationships when studying these responses. In this study, we aimed to understand the combined effects of interspecific interactions and environmental conditions on the demographic parameters of a prey-predator system of three sympatric seabird populations breeding in Antarctica: the south polar skua (Catharacta maccormicki) and its two main preys during the breeding season, the Adélie penguin (Pygoscelis adeliae) and the emperor penguin (Aptenodytes forsteri). We built a two-species integrated population model (IPM) with 31 years of capture-recapture and count data and provided a framework that made it possible to estimate the demographic parameters and abundance of a predator-prey system in a context where capture-recapture data were not available for one species. Our results showed that predator-prey interactions and local environmental conditions differentially affected south polar skuas depending on their breeding state of the previous year. Concerning prey-predator relationships, the number of Adélie penguin breeding pairs showed a positive effect on south polar skua survival and breeding probability, and the number of emperor penguin dead chicks showed a positive effect on the breeding success of south polar skuas. In contrast, there was no evidence for an effect of the number of south polar skuas on the demography of Adélie penguins. We also found an important impact of sea ice conditions on both the dynamics of south polar skuas and Adélie penguins. Our results suggest that this prey-predator system is mostly driven by bottom-up processes and local environmental conditions.

Spread of antibiotic resistance genes to Antarctica by migratory birds.

Recent studies have highlighted the presence of antibiotic resistance genes (ARGs) in Antarctica, which are typically indicative of human activity. However, these studies have concentrated in the Antarctic Peninsula region, and relatively less is known about ARG prevalence in East Antarctica, where human activity levels are lower compared to the Antarctic Peninsula. In addition, the mechanisms of ARG transmission to Antarctica through natural or anthropogenic pathways remain unclear. In this study, we analyzed the fecal samples of Adélie penguins and South polar skuas by using high-throughput sequencing and microfluidic quantitative PCR to detect potential pathogens and ARGs at their breeding colonies near Syowa Station in East Antarctica. These results revealed the presence of several potential pathogens in the fecal matter of both bird species. However, the HF183 marker, which indicates human fecal contamination, was absent in all samples, as well as seawater sampled near the breeding colonies. This suggests that the human fecal contamination was negligible in our study area. In addition to pathogens, we found a significant number of ARGs and metal resistance genes in the feces of both Adélie penguins and South polar skuas, with higher detection rates in skuas than in penguins. To better understand how these birds acquire and transmit these genes, we analyzed the migratory patterns of Adélie penguins and South polar skuas by geolocator tracking. We found that the skuas migrate to the tropical and subtropical regions of the Indian Ocean during the austral winter. On the other hand, Adélie penguins exhibited a more localized migration pattern, mainly staying within Antarctic waters. Because the Indian Ocean is considered one of the major reservoirs of ARGs, South polar skuas might be exposed to ARGs during their winter migration and transfer these genes to Antarctica.

Living in a challenging environment: Monitoring stress ecology by non-destructive methods in an Antarctic seabird.

How Antarctic species are facing historical and new stressors remains under-surveyed and risks to wildlife are still largely unknown. Adélie penguins Pygoscelis adeliae are well-known bioindicators and sentinels of Antarctic ecosystem changes, a true canary in the coal mine. Immuno-haematological parameters have been proved to detect stress in wild animals, given their rapid physiological response that allows them tracking environmental changes and thus inferring habitat quality. Here, we investigated variation in Erythrocyte Nuclear Abnormalities (ENAs) and White Blood Cells (WBCs) in penguins from three clustered colonies in the Ross Sea, evaluating immuno-haematological parameters according to geography, breeding stage, and individual penguin characteristics such as sex, body condition and nest quality. Concentrations of mercury (Hg) and stable isotopes of carbon and nitrogen (as proxies of the penguin's trophic ecology) were analysed in feathers to investigate the association between stress biomarkers and Hg contamination in Adélie penguins. Colony and breeding stage were not supported as predictors of immuno-haematological parameters. ENAs and WBCs were respectively ∼30 % and ∼20 % higher in male than in female penguins. Body condition influenced WBCs, with penguins in the best condition having a ∼22 % higher level of WBCs than those in the worst condition. Nest position affected the proportion of micronuclei (MNs), with inner-nesting penguins having more than three times the proportion of MNs than penguins nesting in peripheral positions. Heterophils:Lymphocytes (H:L) ratio was not affected by any of the above predictors. Multiple factors acting as stressors are expected to increase prominently in Antarctic wildlife in the near future, therefore extensive monitoring aimed to assess the health status of penguin populations is mandatory.

Ancient and Modern Genomes Reveal Microsatellites Maintain a Dynamic Equilibrium Through Deep Time.

Microsatellites are widely used in population genetics, but their evolutionary dynamics remain poorly understood. It is unclear whether microsatellite loci drift in length over time. This is important because the mutation processes that underlie these important genetic markers are central to the evolutionary models that employ microsatellites. We identify more than 27 million microsatellites using a novel and unique dataset of modern and ancient Adélie penguin genomes along with data from 63 published chordate genomes. We investigate microsatellite evolutionary dynamics over 2 timescales: one based on Adélie penguin samples dating to ∼46.5 ka and the other dating to the diversification of chordates aged more than 500 Ma. We show that the process of microsatellite allele length evolution is at dynamic equilibrium; while there is length polymorphism among individuals, the length distribution for a given locus remains stable. Many microsatellites persist over very long timescales, particularly in exons and regulatory sequences. These often retain length variability, suggesting that they may play a role in maintaining phenotypic variation within populations.

Sex-specific recruitment rates contribute to male-biased sex ratio in Adélie penguins.

Sex-related differences in vital rates that drive population change reflect the basic life history of a species. However, for visually monomorphic bird species, determining the effect of sex on demographics can be a challenge. In this study, we investigated the effect of sex on apparent survival, recruitment, and breeding propensity in the Adélie penguin (Pygoscelis adeliae), a monochromatic, slightly size dimorphic species with known age, known sex, and known breeding history data collected during 1996-2019 (n = 2127 birds) from three breeding colonies on Ross Island, Antarctica. Using a multistate capture-mark-recapture maximum-likelihood model, we estimated apparent survival (S^), recapture (resighting) probability (p^), and the probability of transitioning among breeding states and moving between colonies (ψ^; colony-specific non-juvenile pre-breeders, breeders, and non-breeders). Survival rate varied by breeding status and colony, but not sex, and pre-breeders had higher survival rates than breeders and non-breeders. Females had a higher probability of recruiting into the breeding population each year and may enter the breeding pool at younger ages. In contrast, both sexes had the same probability of breeding from year to year once they had recruited. Although we detected no direct sex effects on survival, the variation in recruitment probability and age-at-first reproduction, along with lower survival rates of breeders compared to pre-breeders, likely leads to shorter lifespans for females. This is supported by our findings of a male-biased mean adult sex ratio (ASR) of 1.4 males for every female (x^ proportion of males = 0.57, SD = 0.07) across all colonies and years in this metapopulation. Our study illustrates how important it can be to disentangle sex-related variation in population vital rates, particularly for species with complex life histories and demographic dynamics.

Corynebacterium mendelii sp. nov., a novel bacterium isolated from Adélie penguin oral cavity.

The taxonomic status of strain P5891T, isolated from an Adélie penguin beak swab, was investigated. Based on the 16S rRNA gene sequence, the strain was identified as a potentially novel Corynebacterium species, with the highest sequence similarities to Corynebacterium rouxii FRC0190T (96.7 %) and Corynebacterium epidermidicanis DSM 45586T (96.6 %). The average nucleotide identity values between strain P5891T and C. rouxii FRC0190T and C. epidermidicanis DSM 45586T were 68.2 and 69.2 %, respectively. The digital DNA-DNA hybridization values between strain P5891T and C. rouxii FRC0190T and C. epidermidicanis DSM 45586T were 23.7 and 21.4 %, respectively. Phylogenetic trees based on the 16S rRNA sequence placed strain P5891T in a separate branch with Corynebacterium canis 1170T and Corynebacterium freiburgense 1045T, while a phylogenomic tree based on the Corynebacterium species core genome placed the strain next to Corynebacterium choanae 200CHT. Extensive phenotyping and genomic analyses clearly confirmed that strain P5891T represents a novel species of the genus Corynebacterium, for which the name Corynebacterium mendelii sp. nov. is proposed, with the type strain P5891T (=CCM 8862T=LMG 31627T).

Environmental Drivers of Growth and Oxidative Status during Early Life in a Long-Lived Antarctic Seabird, the Adélie Penguin.

AbstractIn vertebrates, developmental conditions can have long-term effects on individual performance. It is increasingly recognized that oxidative stress could be one physiological mechanism connecting early-life experience to adult phenotype. Accordingly, markers of oxidative status could be useful for assessing the developmental constraints encountered by offspring. Although some studies have demonstrated that developmental constraints are associated with high levels of oxidative stress in offspring, it remains unclear how growth, parental behavior, and brood competition may altogether affect oxidative stress in long-lived species in the wild. Here, we investigated this question in a long-lived Antarctic bird species by testing the impact of brood competition (e.g., brood size and hatching order) on body mass and on two markers of oxidative damage in Adélie penguin chicks. We also examined the influence of parental effort (i.e., foraging trip duration) and parental body condition on chick body mass and oxidative damage. First, we found that brood competition and parental traits had significant impacts on chick body mass. Second, we found that chick age and, to a lesser extent, chick body mass were two strong determinants of the levels of oxidative damage in Adélie penguin chicks. Finally, and importantly, we also found that brood competition significantly increased the levels of one marker of oxidative damage and was associated with a lower survival probability. However, parental effort and parental condition were not significantly linked to chick levels of oxidative damage. Overall, our study demonstrates that sibling competition can generate an oxidative cost even for this long-lived Antarctic species with a limited brood size (maximum of two chicks).

Positive Atlantic Multidecadal Oscillation has driven poleward redistribution of the West Antarctic Peninsula biota through a food-chain mechanism.

The West Antarctic Peninsula (WAP) has recorded a significant poleward range shift in marine biota, including Adélie penguins, Antarctic krill and phytoplankton. The ecological changes have been widely attributed to Pacific/Southern Hemisphere variabilities. However, the teleconnection from the North Atlantic Ocean, which also could induce changes in the WAP physical environments, has been overlooked. Here we combine state-of-the-art observational/modelling databases to quantify the poleward redistribution since the 1980s of three key members of the WAP biota and explored their response to several climatic oscillations. The abundance of Adélie penguins, Antarctic krill and phytoplankton in the WAP all show a decrease in the north and an increase in the south, leading to a poleward shift of their distribution centers by ~0.8-2.3°. A more positive Atlantic Multidecadal Oscillation (AMO) has contributed to the poleward redistribution of phytoplankton/krill/penguin with a time lag of 0/1/5 yr, indicating a food-chain related mechanism. +AMO in spring resulted in reduced sea ice, earlier ice retreat and enhanced winds in the northern WAP, which constrained phytoplankton blooms and krill reproduction, thereby decreasing the krill recruitment 1 yr later and consequently the penguin recruitment 5 yr later. In the southern WAP, where the sea ice cover was nearly permanent in the 1980s, reduced sea ice and earlier ice retreat promoted phytoplankton growth and krill/penguin reproduction. Our results emphasize the global nature of climate-ecological coupling; the influence of the Northern Hemisphere climate system on Antarctic/Southern Ocean biota is a non-negligible factor for the ecosystem management.

Corynebacterium antarcticum sp. nov., Corynebacterium marambiense sp. nov., Corynebacterium meridianum sp. nov., and Corynebacterium pygosceleis sp. nov., isolated from Adélie penguins (Pygoscelis adeliae).

A taxonomic study was conducted on 16 bacterial strains isolated from wild Adélie penguins (Pygoscelis adeliae) from Seymour (Marambio) Island and James Ross Island. An initial screening by repetitive sequence-based PCR fingerprinting divided the strains studied into four coherent groups. Phylogenetic analysis based on 16S rRNA gene sequences assigned all groups to the genus Corynebacterium and showed that Corynebacterium glyciniphilum and Corynebacterium terpenotabidum were the closest species with 16S rRNA gene sequence similarities between 95.4 % and 96.5 %. Further examination of the strains studied with ribotyping, MALDI-TOF mass spectrometry, comprehensive biotyping and calculation of average nucleotide identity and digital DNA-DNA hybridisation values confirmed the separation of the four groups from each other and from the other Corynebacterium species. Chemotaxonomically, the four strains P5828T, P5850T, P6136T, P7210T representing the studied groups were characterised by C16:0 and C18:1ω9c as the major fatty acids, by the presence of meso-diaminopimelic acid in the peptidoglycan, the presence of corynemycolic acids and a quinone system with the predominant menaquinone MK-9(H2). The results of this study show that the strains studied represent four new species of the genus Corynebacterium, for which the names Corynebacterium antarcticum sp. nov. (type strain P5850T = CCM 8835T = LMG 30620T), Corynebacterium marambiense sp. nov. (type strain P5828T = CCM 8864T = LMG 31626T), Corynebacterium meridianum sp. nov. (type strain P6136T = CCM 8863T = LMG 31628T) and Corynebacterium pygosceleis sp. nov. (type strain P7210T = CCM 8836T = LMG 30621T) are proposed.

South polar skua (Catharacta maccormicki) as biovectors for long-range transport of persistent organic pollutants to Antarctica.

Migratory bird species may serve as vectors of contaminants to Antarctica through the local deposition of guano, egg abandonment, or mortality. To further investigate this chemical input pathway, we examined the contaminant burdens and profiles of the migratory South polar skua (Catharacta maccormicki) and compared them to the endemic Adélie penguin (Pygoscelis adeliae). A range of persistent organic pollutants were targeted in muscle and guano to facilitate differentiation of likely exposure pathways. A total of 56 of 65 targeted analytes were detected in both species, but there were clear profile and magnitude differences between the species. The South polar skua and Adélie penguin muscle tissue burdens were dominated by p,p'-dichlorodiphenyldichloroethylene (mean 5600 ng g-1 lw and 330 ng g-1 lw respectively) and hexachlorobenzene (mean 2500 ng g-1 lw and 570 ng g-1 lw respectively), a chemical profile characteristic of the Antarctic and Southern Ocean region. Species profile differences, indicative of exposure at different latitudes, were observed for polychlorinated biphenyls (PCBs), with lower chlorinated congeners and deca-chlorinated PCB-209 detected in South polar Skua, but not in Adélie penguins. Notably, the more recently used perfluoroalkyl substances and the brominated flame retardants, hexabromocyclododecane and tetrabromobisphenol A, were detected in both species. This finding suggests local exposure, given the predicted slow and limited long-range environmental transport capacity of these compounds to the eastern Antarctic sector.

Regional Differences in the Diets of Adélie and Emperor Penguins in the Ross Sea, Antarctica.

To identify the dietary composition and characteristics of both Adélie (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) penguins at four breeding sites, we performed stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of down samples taken from penguin chicks. Adélie Penguin chicks at Cape Hallett mostly fed on Antarctic krill (Euphausia superba; 65.5 ± 3.5%), a reflection of the prevalence of that species near Cape Hallett, and no significant differences were noted between 2017 and 2018. However, Adélie Penguin chicks at Inexpressible Island, located near Terra Nova Bay, fed on both Antarctic silverfish (Pleuragramma antarctica; 42.5%) and ice krill (Euphausia crystallorophias; 47%), reflecting the high biomass observed in Terra Nova Bay. Meanwhile, no significant difference was noted between the two breeding sites of the Emperor Penguin. Emperor Penguin chicks predominantly fed on Antarctic silverfish (74.5 ± 2.1%) at both breeding sites (Cape Washington and Coulman Island), suggesting that diet preference represents the main factor influencing Emperor Penguin foraging. In contrast, the diet of the Adélie Penguin reflects presumed regional differences in prey prevalence, as inferred from available survey data.

Emerging evidence of resource limitation in an Antarctic seabird metapopulation after 6 decades of sustained population growth.

The influence of resource limitation on spatio-temporal population dynamics is a fundamental theme in ecology and the concepts of carrying capacity, density dependence and population synchrony are central to this theme. The life history characteristics of seabirds, which include use of disjunct patches of breeding habitat, high coloniality during breeding, strong philopatry, and central-place foraging, make this group well suited to studying this paradigm. Here, we investigate whether density-dependent processes are starting to limit population growth in the Adélie penguin metapopulation breeding in the Windmill Islands, East Antarctica, after 6 decades of growth. Our finding that the regional growth rate has slowed in recent decades, and that growth is slowing differentially across local populations as availability of breeding habitat and possibly food resources decrease, supports the notion of density-dependent regulation. Our observation of the first new colonisation of a breeding patch in a half-century of population growth by this highly philopatric species is further evidence for this. Given these emerging patterns of spatio-temporal population dynamics, this metapopulation may be at a point where the rate of change in density-dependent processes and rare events such as colonisations accelerates into the future, potentially providing new insights into spatio-temporal metapopulation dynamics of a long-lived species over a short time-frame. Continued long-term study of populations experiencing these circumstances provides an opportunity to expedite advances in understanding metapopulation processes. Our study highlights the importance of spatial heterogeneity and the mosaic of abiotic and biotic features of landscapes and seascapes in shaping species' metapopulation dynamics.

Age-related reproductive performance of the Adélie penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy.

Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

Antarctic Adélie penguin feathers as bio-indicators of geographic and temporal variations in heavy metal concentrations in their habitats.

Seabird feathers are effective indicators of heavy metal contamination. To propose a biological detection method suitable for the long-term monitoring of heavy metals in the Antarctic environment, eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in Adélie penguin feathers from different body parts, years, and molting grounds in the Antarctic were investigated in this study. It is found that the concentrations of heavy metals in the feathers showed differences among the body part of origin. The levels of the eight elements in the abdomen and back feathers were approximately the same, but some elements of them were significantly higher than those in the tail feathers. The Hg and Cd concentrations in the abdomen and back feathers increased from root to tip, regardless of the sampling year or molting ground. Based on a structural analysis of the feathers, Hg and Cd were mainly distributed in the feather vane rather than the shaft. The methylmercury content accounted for 83%-97% of the total mercury content in all feather samples, regardless of location, year, or body part, thereby supporting the assumption that mercury entering the feather was predominantly methylated and indicating that a relatively toxic form of Hg is excreted through the feathers. The heavy metals in feathers from the same molting ground showed significant differences over the sampling years. The average concentrations of As, Cr, Cu, Ni, and Zn increased significantly from 2015 to 2019, whereas those of Cd, Hg, and Pb tended to decrease. The concentrations of the eight elements in Adélie feathers from three molting grounds varied greatly, possibly in relation to their living areas and dietary structures. Feathers from the Ross Sea site had the highest Cd, Cu, Hg, Ni, and Zn concentrations, the highest As and Cr concentrations were detected in feathers from the Zhongshan site, and feathers from the Great Wall site showed higher Pb concentrations than those from the other two sites. This study established a long-term, nondestructive, and efficient method for monitoring heavy metal contamination in the polar environment in the future.

Density dependence forces divergent population growth rates and alters occupancy patterns of a central place foraging Antarctic seabird.

Density-dependent regulation is an important process in spatio-temporal population dynamics because it can alter the effects of synchronizing processes operating over large spatial scales. Most frequently, populations are regulated by density dependence when higher density leads to reduced individual fitness and population growth, but inverse density dependence can also occur when small populations are subject to higher extinction risks. We investigate whether density-dependent regulation influences population growth for the Antarctic breeding Adélie penguin Pygoscelis adeliae. Understanding the prevalence and nature of density dependence for this species is important because it is considered a sentinel species reflecting the impacts of fisheries and environmental change over large spatial scales in the Southern Ocean, but the presence of density dependence could introduce uncertainty in this role. Using data on population growth and indices of resource availability for seven regional Adélie penguin populations located along the East Antarctic coastline, we find compelling evidence that population growth is constrained at some locations by the amount of breeding habitat available to individuals. Locations with low breeding habitat availability had reduced population growth rates, higher overall occupancy rates, and higher occupancy of steeper slopes that are sparsely occupied or avoided at other locations. Our results are consistent with evolutionary models of avian breeding habitat selection where individuals search for high-quality nest sites to maximize fitness returns and subsequently occupy poorer habitat as population density increases. Alternate explanations invoking competition for food were not supported by the available evidence, but strong conclusions on food-related density dependence were constrained by the paucity of food availability data over the large spatial scales of this region. Our study highlights the importance of incorporating nonconstant conditions of species-environment relationships into predictive models of species distributions and population dynamics, and provides guidance for improved monitoring of fisheries and climate change impacts in the Southern Ocean.

Characterization of Staphylococcus intermedius Group Isolates Associated with Animals from Antarctica and Emended Description of Staphylococcus delphini.

Members of the genus Staphylococcus are widespread in nature and occupy a variety of niches, however, staphylococcal colonization of animals in the Antarctic environment has not been adequately studied. Here, we describe the first isolation and characterization of two Staphylococcus intermedius group (SIG) members, Staphylococcus delphini and Staphylococcus pseudintermedius, in Antarctic wildlife. Staphylococcus delphini were found exclusively in Adélie penguins. The report of S. pseudintermedius from Weddell seals confirmed its occurrence in all families of the suborder Caniformia. Partial RNA polymerase beta-subunit (rpoB) gene sequencing, repetitive PCR fingerprinting with the (GTG)5 primer, and matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry gave consistent identification results and proved to be suitable for identifying SIG members. Comparative genomics of S. delphini isolates revealed variable genomic elements, including new prophages, a novel phage-inducible chromosomal island, and numerous putative virulence factors. Surface and extracellular protein distribution were compared between genomes and showed strain-specific profiles. The pathogenic potential of S. delphini was enhanced by a novel type of exfoliative toxin, trypsin-like serine protease cluster, and enterotoxin C. Detailed analysis of phenotypic characteristics performed on six Antarctic isolates of S. delphini and eight reference strains from different animal sources enabled us to emend the species description of S. delphini.

The interaction between island geomorphology and environmental parameters drives Adélie penguin breeding phenology on neighboring islands near Palmer Station, Antarctica.

Despite many studies on Adélie penguin breeding phenology, understanding the drivers of clutch initiation dates (CIDs, egg 1 lay date) is limited or lacks consensus. Here, we investigated Adélie penguin CIDs over 25 years (1991-2016) on two neighboring islands, Torgersen and Humble (<1 km apart), in a rapidly warming region near Palmer Station, Antarctica. We found that sea ice was the primary large-scale driver of CIDs and precipitation was a secondary small-scale driver that fine-tunes CID to island-specific nesting habitat geomorphology. In general, CIDs were earlier (later) when the spring sea ice retreat was earlier (later) and when the preceding annual ice season was shorter (longer). Island-specific effects related to precipitation and island geomorphology caused greater snow accumulation and delayed CIDs by ~2 days on Torgersen compared to Humble Island. When CIDs on the islands were similar, conditions were mild with less snow across breeding sites. At Torgersen Island, the negative relationship between CID and breeding success highlights detrimental effects of delayed breeding and/or snow on penguin fitness. Past phenological studies reported a relationship between air temperature and CID, assumed to be related to precipitation, but we found air temperature was more highly correlated to sea ice, revealing a misinterpretation of temperature effects. Finally, contrasting trends in CIDs based on temporal shifts in regional sea ice patterns revealed trends toward earlier CIDs (4-6 day advance) from 1979 to 2009 as the annual ice season shortened, and later CIDs (7-10 day delay) from 2010 to 2016 as the annual ice season lengthened. Adélie penguins tracked environmental conditions with flexible breeding phenology, but their life history remains vulnerable to subpolar weather conditions that can delay CIDs and decrease breeding success, especially on landscapes where geomorphology facilitates snow accumulation.

When the "selfish herd" becomes the "frozen herd": spatial dynamics and population persistence in a colonial seabird.

Aggregations are common in ecological systems at a range of scales and may be driven by exogenous constraints such as environmental heterogeneity and resource availability or by "self-organizing" interactions among individuals. One mechanism leading to self-organized animal aggregations is captured by Hamilton's "selfish herd" hypothesis, which suggests that aggregations may be driven by an individual's effort to minimize their risk of predation by surrounding themselves with conspecifics. We demonstrate that aggregations observed in Adélie Penguin (Pygoscelis adeliae) colonies are a convolution of both self-organized dynamics and external forcing arising from landscape terrain. In fluid, highly mobile aggregations, individuals are constantly moving in response to changing environmental conditions, the locations of predators, or the movements of conspecifics. However, when the ability to rearrange is limited and spatial reconfiguration occurs on slower time scales than changes in population size, systems may become trapped in suboptimal arrangements. We use simulated annealing to demonstrate that Adélie Penguin colonies are frozen in suboptimal spatial arrangements, and employ an individual-based modeling approach to demonstrate that this suboptimal spatial configuration is driven by a convolution of nest site fidelity and stochastic events at the level of individual nests. The resulting spatial dynamics are responsible for a hysteretic response to long-term changes in abundance. We find that declining abundance leads to fragmentation even in a homogeneous environment, which has population-level consequences for reproductive success because predation is biased towards colony edges. Strong edge effects from heterogeneous predation coupled with fragmentation in response to population declines create a positive feedback cycle that can accelerate population decline. This work provides a mechanistic understanding of complex spatial structuring in penguin colonies, provides a link between current spatial patterning and past dynamics, and suggests the possibility of critical collapse in seabird populations.

Antarctic Penguins as Reservoirs of Diversity for Avian Avulaviruses.

Wild birds harbor a huge diversity of avian avulaviruses (formerly avian paramyxoviruses). Antarctic penguin species have been screened for avian avulaviruses since the 1980s and, as such, are known hosts of these viruses. In this study, we screened three penguin species from the South Shetland Islands and the Antarctic Peninsula for avian avulaviruses. We show that Adelie penguins (Pygoscelis adeliae) are hosts for four different avian avulavirus species, the recently described avian avulaviruses 17 to 19 and avian avulavirus 10-like, never before isolated in Antarctica. A total of 24 viruses were isolated and sequenced; avian avulavirus 17 was the most common, and phylogenetic analysis demonstrated patterns of occurrence, with different genetic clusters corresponding to penguin age and location. Following infection in specific-pathogen-free (SPF) chickens, all four avian avulavirus species were shed from the oral cavity for up to 7 days postinfection. There was limited shedding from the cloaca in a proportion of infected chickens, and all but one bird seroconverted by day 21. No clinical signs were observed. Taken together, we propose that penguin species, including Antarctic penguins, may be the central reservoir for a diversity of avian avulavirus species and that these viruses have the potential to infect other avian hosts.IMPORTANCE Approximately 99% of all viruses are still to be described, and in our changing world, any one of these unknown viruses could potentially expand their host range and cause epidemic disease in wildlife, agricultural animals, or humans. Avian avulavirus 1 causes outbreaks in wild birds and poultry and is thus well described. However, for many avulavirus species, only a single specimen has been described, and their viral ecology and epidemiology are unknown. Through the detection of avian avulaviruses in penguins from Antarctica, we have been able to expand upon our understanding of three avian avulavirus species (avian avulaviruses 17 to 19) and report a potentially novel avulavirus species. Importantly, we show that penguins appear to play a key role in the epidemiology of avian avulaviruses, and we encourage additional sampling of this avian group.