Abstract: The cephalopod diet of the light-mantled sooty albatross Phoebetria palpebrata was determined for the first time at the subantarctic Kerguelen Islands by sorting ∼7000 accumulated beaks from 66 regurgitated boluses. Twenty-two taxa were identified, including four dominant squid species that are all endemic to the Southern Ocean: Galiteuthis glacialis (49.8% of the lower beaks) Psychroteuthis glacialis (18.5%), Martialia hyadesi (16.2%) and Moroteuthopsis longimana (6.9%). Beak δ13C values indicated that all adult P. glacialis, almost all juvenile M. longimana, and most adult G. glacialis were caught in Antarctic waters, while albatrosses preyed upon juvenile M. hyadesi in subantarctic waters. Comparative analysis of lower beaks accumulated in food samples of Kerguelen albatrosses showed that the four main sympatric albatross species segregate primarily by species-specific foraging grounds. Light-mantled sooty albatross feed on the Antarctic P. glacialis, wandering albatross Diomedea exulans on subantarctic and subtropical histioteuthids (41.4%), and grey-headed albatross Thalassarche chrysostoma and black-browed albatross T. melanophris on subantarctic ommastrephids (69.3% and 65.7%, respectively), with black-browed albatross also preying upon neritic endemic octopuses (17.6%). Cephalopod prey of Kerguelen albatrosses highlight the abundance and importance of some squids in the functioning of the pelagic ecosystem of the southern Indian Ocean, such as ommastrephids, M. longimana, P. glacialis, Histioteuthis atlantica, H. eltaninae, and G. glacialis. Based on the diet of the light-mantled sooty albatross, P. glacialis appears common in high-Antarctic waters of the southern Indian Ocean, whereas the poorly known Psychroteuthis sp. B (Imber) is evidently present in Antarctic waters south of the Kerguelen Islands.

Abstract: Maternal effects are thought to be essential tools for females to modulate offspring development. The selective deposition of avian maternal hormones could therefore allow females to strategically adjust the phenotype of their offspring to the environmental situation encountered. However, at the time of egg formation, several contaminants are also transferred to the egg, including per- and polyfluoroalkyl substances (PFAS) which are ubiquitous organic contaminants with endocrine disrupting properties. It is, however, unknown if they can disrupt maternal hormone deposition. In this study we explored relationships between female PFAS burden and maternal deposition in the eggs of steroids (dihydrotestosterone, androstenedione and testosterone), glucocorticoids (corticosterone) and thyroid hormones (triiodothyronine and thyroxine) in a population of the Arctic-breeding black-legged kittiwake (Rissa tridactyla). Egg yolk hormone levels were unrelated to female hormone plasma levels. Second-laid eggs had significantly lower concentrations of androstenedione than first-laid eggs. Triiodothyronine yolk levels were decreasing with increasing egg mass but increasing with increasing females' body condition. Testosterone was the only transferred yolk hormone correlated to maternal PFAS burden: specifically, we found a positive correlation between testosterone in yolks and circulating maternal perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDcA) and perfluoroundecanoic acid (PFUnA) in first-laid eggs. This correlative study provides a first insight into the potential of some long-chain perfluoroalkyl acids to disrupt maternal hormones deposition in eggs and raises the question about the consequences of increased testosterone deposition on the developing embryo.

Abstract: A location in the Gulf of Guinea, which emits monochromatic seismic waves at 26-second period, seemingly continuously, was identified in the 1960s. However, the origin of these seismic waves remains enigmatic to date. Here we use three-component data from two seismic arrays in Africa, as well as additional seismic data compiled from around the world, to investigate the tremors. We identify frequency glides accompanying the previously known 26 s microseism which start at the same frequency and originate in the same, fixed location in the Gulf of Guinea. The stable characteristics of the tremors, their low frequency range, the implied large spatial scale, and the decades-long timescales where this phenomenon seems to have been active, all point towards a gap in our understanding of long period oceanic and volcanic signals. Since tremor is an important tool to monitor volcanoes, understanding this phenomenon may affect future forecasting of volcanic activity.

Abstract: Wildlife movement ecology often focuses on breeders, whose territorial attachments facilitate trapping and following individuals over time. This leads to incomplete understanding of movements of individuals not actively breeding due to age, breeding failure, subordinance, and other factors. These individuals are often present in breeding populations and contribute to processes such as competition and pathogen spread. Therefore, excluding them from movement ecology studies could bias or mask important spatial dynamics. Loafing areas offer an alternative to breeding sites for capturing and tracking individuals. Such sites may allow for sampling individuals regardless of breeding status, while also avoiding disturbance of sensitive breeding areas. However, little is known about the breeding status of individuals attending loafing sites, or how their movements compare to those of breeders captured at nests. We captured a seabird, the brown skua, attending either nests or loafing areas (‘clubs’) at a multi-species seabird breeding site on Amsterdam Island (southern Indian Ocean). We outfitted skuas with GPS-UHF transmitters and inferred breeding statuses of individuals captured at clubs using movement patterns of breeders captured at nests. We then compared space use and activity patterns between breeders and nonbreeders. Both breeding and nonbreeding skuas attended clubs. Nonbreeders ranged more widely, were more active, and overlapped more with other seabirds and marine mammals than did breeders. Moreover, some nonbreeders occupied fixed territories and displayed more restricted movements than those without territories. Nonbreeders became less active over the breeding season, while activity of breeders remained stable. Nonbreeding skuas were exposed to the agent of avian cholera at similar rates to breeders but were more likely to forage in breeding areas of the endangered endemic Amsterdam albatross, increasing opportunities for interspecific pathogen transmission. Our results show that inference based only on breeders fails to capture important aspects of population-wide movement patterns. Capturing nonbreeders as well as breeders would help to improve population-level representation of movement patterns, elucidate and predict effects of external changes and conservation interventions (e.g. rat eradication) on movement patterns and pathogen spread, and develop strategies to manage outbreaks of diseases such as highly pathogenic avian influenza. Read the free Plain Language Summary for this article on the Journal blog.

Abstract: 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.