Geology topics

Megan Elrod

Publications and source records attributed to Megan Elrod.

9 recordsLinked to original sources

USGS2026

Importance of fish in the diet of Adélie penguins across multiple life stages

Over recent decades, the Adélie penguin ( Pygoscelis adeliae ) population has grown across most of its range, the exception being the northern coast of the western Antarctic Peninsula (WAP). In the Ross Sea, the very large Cape Crozier colony grew to reach ~9% of the global population. Demographic factors driving the Cape Crozier trend have yet to be identified. However, low chick fledging mass - a negative influence in the northern WAP where the diet is mostly less-energy-dense krill - is not showing an effect in the Cape Crozier colony. Previously, we hypothesized that Cape Crozier fledglings, and post-breeding adults, must be finding sufficient higher-quality prey once free of the prey-depleted colony foraging area, with subsequent higher survival. Here we explore penguin diet within and outside the colony foraging area using stable isotope analysis (SIA) of feathers: those grown by post-breeding adults outside the foraging area, prior to moult, compared to those of near-fledged chicks raised on meals obtained within the foraging area. Second, we explore whether a major difference occurs between breeding and post-breeding diet of adults from a small, nearby colony (Cape Royds) that exploits a smaller, little-depleted preyscape. Finally, we compare the results to SIA analyses published by others to explore whether the pre-moult diet of Ross Island adults, mostly foraging within the north-eastern Ross Sea, compares with that of adults nesting in the southern WAP (Bellingshausen Sea coast). At the latter, populations are not decreasing, with diet containing an appreciable contribution of fish. The results confirmed that fish contributed greatly to chick diets at both Ross Island colonies (δ 15 N 10.6–11.4). Once adults were released from central-place foraging, SIA levels (δ 15 N 9.7–12.9) were similar to those of the southern WAP. Foraging on energy-dense fish in coastal Antarctic waters could be one reason Adélie penguins are among the most abundant and therefore most ecologically successful penguin species.

Antarctic Science↗

USGS2026

Novel avian papillomaviruses identified in a south polar skua sampled on Ross Island, Antarctica

Papillomaviruses are small circular DNA viruses that infect epithelial cells of their hosts. Avian papillomaviruses are poorly sampled/documented compared to those infecting humans. We used a viral metagenomic approach to identify viruses from the oral swab taken from a deceased south polar skua ( Stercorarius maccormicki ) found at Cape Royds, Ross Island, Antarctica in late 2024. We identified three papillomaviruses and determined their complete genomes, Stercorarius maccormicki papillomavirus (SmacPV) 1-3. SmacPV1 is the most divergent of the three SmacPVs, sharing 62% genome-wide pairwise identity to SmacPV2 and SmacPV3 and <63.5% to other avian papillomaviruses. The genomes of SmacPV2 and SmacPV3 represent two new papillomavirus types sharing 82.4% genome-wide pairwise identity with each other and <72% to other papillomaviruses. SmacPV2 and SmacPV3 phylogenetically cluster with sequences of the Rissa tridactyla papillomavirus 1 from black-legged kittiwake ( Rissa tridactyla ), Larus smithsonianus papillomavirus 1 from American herring gull ( Larus smithsonianus ) and Fratercula arctica papillomavirus 1 from Atlantic puffin ( Fratercula arctica ), and they collectively represent a new papillomavirus species. These are the first papillomaviruses to be identified in Stercorarius spp . and add to the handful of known papillomaviruses in identified avian species. We also expand the known host range of papillomaviruses in Antarctic animals, which previously included Adélie penguins ( Pygoscelis adeliae ), Weddell seals ( Leptonychotes weddellii ), Antarctic fur seals ( Arctocephalus gazella ), leopard seals ( Hydrurga leptonyx ) and emerald notothen ( Trematomus bernacchii ).

Archives of Virology↗

USGS2026

Timing the tuxedo transformation: Moult phenology reflects breeding investment and intrinsic constraints in Adélie penguins

Vertebrate life histories are often divided into distinct periods, with the breeding season typically receiving the most research attention. For polar seabirds, non-breeding phases like moult remain understudied, despite their importance for survival and overall fitness. Adélie penguins ( Pygoscelis adeliae ) replace their highly specialized feathers during an approximately 19-day annual moult, typically carried out while fasting on sea ice. The required fast and elevated metabolic rate may create a significant energetic bottleneck. We analysed data from geolocating dive recorders deployed on known-age Adélie penguins and non-known-age pairs from two Ross Island colonies over three winters (2017–2019). Moult start date was influenced by breeding success, intrinsic factors (age, sex) and extrinsic factors (year), with males, older birds and successful breeders moulting later. Moult duration varied primarily with individual ID, though later initiation correlated with shorter duration, particularly when located further south. Moult duration was longer in the western Ross Sea, a region that was used exclusively by males. The association between moult start date and duration may lead to differential sex and breeding status effects, with older males more likely to face a trade-off between successful breeding and self-maintenance tasks like feather replacement.

Proceedings of the Royal Society B↗

USGS2025

Diversity of polyomaviruses and papillomaviruses in penguins from eastern and western Antarctica

Polyomaviruses and papillomaviruses are icosahedral viruses with small circular dsDNA genomes. Limited information on their diversity and evolution in avian hosts is available, with even less known regarding Antarctic penguins. Prior to this study, only one polyomavirus and two papillomaviruses had been identified in Adélie penguins ( Pygoscelis adeliae ). To expand our knowledge of these viruses in Antarctic penguins, we collected faecal and cloacal swab samples from 246 Adélie penguins over 3 breeding seasons (2021–2024) and 10 emperor penguins ( Aptenodytes forsteri ) during the 2023–2024 season on Ross Island (Ross Sea). Additionally, we sampled 66 Adélie, 40 chinstrap ( Pygoscelis antarcticus ) and 71 gentoo ( Pygoscelis papua ) penguins during the 2022–2023 season across various sites on the Antarctic Peninsula. All samples were screened for papillomaviruses and polyomaviruses. We identified 31 polyomaviruses in Adélie, gentoo and chinstrap penguins and 4 papillomaviruses in Adélie penguins sampled in both eastern and western Antarctica. The 31 penguin polyomaviruses belong to a single species but form four distinct variants that are host species specific with strong geographic clustering. The four papillomaviruses represent three different types, of which two are new types from Adélie penguins sampled on Yalour Island in the West Antarctic Peninsula. Co-occurrence of two polyomavirus variants was identified in two individual gentoo penguins. Both of these variants appear to be circulating in gentoo penguins at Cierva Cove, Hope Bay in Trinity Peninsula along the Antarctic Peninsula, and at Hannah Point on Livingstone Island and Stranger Point on King George Island in the South Shetland Islands. Here, we expand the known diversity, host and geographical ranges of penguin polyomaviruses and, together with a previously identified polyomavirus on Ross Island from 2012 to 2013, show that they form five distinct lineages. The four papillomaviruses identified in this study, together with two previously identified from Ross Island in 2012 and 2013 breeding seasons, show substantial diversity reflecting four papillomavirus types across three viral species and two distinct genera. Continued surveillance and viral genomic analysis across a larger geographical framework will help understand the evolution, transmission and incidence rates of these viruses.

Microbial Genomics↗

USGS2024

Going with the floe: Sea-ice movement affects distance and destination during Adélie penguin winter movements

Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea-ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins ( Pygoscelis adeliae ) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large-scale movement of sea ice. We used remotely sensed sea-ice movement data together with geolocation-based penguin movement data to test the hypothesis that penguins use gyre-driven sea-ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea-ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.

Ecology↗

USGS2023

Sea ice concentration decline in an important Adélie penguin molt area

Unlike in many polar regions, the spatial extent and duration of the sea ice season have increased in the Ross Sea sector of the Southern Ocean during the satellite era. Simultaneously, populations of Adélie penguins, a sea ice obligate, have been stable or increasing in the region. Relationships between Adélie penguin population growth and sea ice concentration are complex, with sea ice driving different, sometimes contrasting, demographic patterns. Adélie penguins undergo a complete molt annually, replacing all their feathers while fasting shortly after the breeding season. Unlike most penguin species, a majority of Adélies are thought to molt on sea ice, away from the breeding colonies, which makes this period particularly difficult to study. Here, we evaluate the hypothesis that persistent areas of high sea ice concentration provide important molting habitat for Adélie penguins. We analyzed data from geolocating dive recorders deployed year-round on 195 adult penguins at two colonies in the Ross Sea from 2017-2019. We identified molt by detecting extended gaps in post-breeding diving activity and used associated locations to define two key molting areas. Remotely sensed data indicated that sea ice concentration during molt was anomalously low during the study and has declined in the primary molt area since 1980. Further, annual return rates of penguins to breeding colonies were positively correlated with sea ice concentration in the molt areas over 20 years. Together these results suggest that sea ice conditions during Adélie penguin molt may represent a previously underappreciated annual bottleneck for adult survival.

PNAS↗

USGS2023

High-resolution recording of foraging behaviour over multiple annual cycles shows decline in old Adélie penguins’ performance

Age-related variation in foraging performance can result from both within-individual change and selection processes. These mechanisms can only be disentangled by using logistically challenging long-term, longitudinal studies. Coupling a long-term demographic data set with high-temporal-resolution tracking of 18 Adélie penguins ( Pygoscelis adeliae , age 4–15 yrs old) over three consecutive annual cycles, we examined how foraging behaviour changed within individuals of different age classes. Evidence indicated within-individual improvement in young and middle-age classes, but a significant decrease in foraging dive frequency within old individuals, associated with a decrease in the dive descent rate. Decreases in foraging performance occurred at a later age (from 12–15 yrs old to 15–18 yrs old) than the onset of senescence predicted for this species (9–11 yrs old). Foraging dive frequency was most affected by the interaction between breeding status and annual life-cycle periods, with frequency being highest during returning migration and breeding season and was highest overall for successful breeders during the chick-rearing period. Females performed more foraging dives per hour than males. This longitudinal, full annual cycle study allowed us to shed light on the changes in foraging performance occurring among individuals of different age classes and highlighted the complex interactions among drivers of individual foraging behaviour.

Proceedings of the Royal Society B↗

USGS2019

Identification of a novel Adélie penguin circovirus at Cape Crozier (Ross Island, Antarctica)

Understanding the causes of disease in Antarctic wildlife is crucial as many of these species are already threatened by environmental changes brought about by climate change. In recent years, Antarctic penguins have been showing signs of an unknown pathology: a feather disorder characterised by missing feathers resulting in exposed skin. During the 2018-19 austral summer breeding season at Cape Crozier colony on Ross Island, Antarctica, for the first time we observed an Adlie penguin chick missing down over most of its body. A guano sample was collected from the nest of the featherless chick and, using high throughput sequencing we identified a novel circovirus. Using abutting primers, we amplified the full genome, which we cloned, and Sanger sequenced to determine the complete genome of the circovirus. The Adlie penguin guano-associated circovirus genome shares <67% genome-wide nucleotide identity to other circoviruses, representing a new species of circovirus, therefore we named it penguin circovirus (PenCV). Using the same primer pair, we screened 25 previously collected cloacal swabs taken at Cape Crozier from known-age adult Adlie penguins during the 2014-15 season displaying no clinical signs of feather-loss disorder. Three of the 25 samples (12%) were positive for a PenCV, whose genome shared >99% pairwise identity to the one identified in 2018-19. This is the first report of a circovirus associated with a penguin species and could be a possible etiological agent of the feather-loss disorder in Antarctic penguins.

Viruses↗

USGS2017

Unique genome organization of non-mammalian papillomaviruses provides insights into the evolution of viral early proteins

The family Papillomaviridae contains more than 320 papillomavirus types, with most having been identified as infecting skin and mucosal epithelium in mammalian hosts. To date, only nine non-mammalian papillomaviruses have been described from birds ( n = 5), a fish ( n = 1), a snake ( n = 1), and turtles ( n = 2). The identification of papillomaviruses in sauropsids and a sparid fish suggests that early ancestors of papillomaviruses were already infecting the earliest Euteleostomi. The Euteleostomi clade includes more than 90 per cent of the living vertebrate species, and progeny virus could have been passed on to all members of this clade, inhabiting virtually every habitat on the planet. As part of this study, we isolated a novel papillomavirus from a 16-year-old female Adélie penguin ( Pygoscelis adeliae ) from Cape Crozier, Ross Island (Antarctica). The new papillomavirus shares ∼64 per cent genome-wide identity to a previously described Adélie penguin papillomavirus. Phylogenetic analyses show that the non-mammalian viruses (expect the python, Morelia spilota , associated papillomavirus) cluster near the base of the papillomavirus evolutionary tree. A papillomavirus isolated from an avian host (Northern fulmar; Fulmarus glacialis ), like the two turtle papillomaviruses, lacks a putative E9 protein that is found in all other avian papillomaviruses. Furthermore, the Northern fulmar papillomavirus has an E7 more similar to the mammalian viruses than the other avian papillomaviruses. Typical E6 proteins of mammalian papillomaviruses have two Zinc finger motifs, whereas the sauropsid papillomaviruses only have one such motif. Furthermore, this motif is absent in the fish papillomavirus. Thus, it is highly likely that the most recent common ancestor of the mammalian and sauropsid papillomaviruses had a single motif E6. It appears that a motif duplication resulted in mammalian papillomaviruses having a double Zinc finger motif in E6. We estimated the divergence time between Northern fulmar-associated papillomavirus and the other Sauropsid papillomaviruses be to around 250 million years ago, during the Paleozoic-Mesozoic transition and our analysis dates the root of the papillomavirus tree between 400 and 600 million years ago. Our analysis shows evidence for niche adaptation and that these non-mammalian viruses have highly divergent E6 and E7 proteins, providing insights into the evolution of the early viral (onco-)proteins.

Virus Evolution↗