Abstract: A prerequisite for environmental and toxicological applications of mercury (Hg) stable isotopes in wildlife and humans is quantifying the isotopic fractionation of biological reactions. Here, we measured stable Hg isotope values of relevant tissues of giant petrels (Macronectes spp.). Isotopic data were interpreted with published HR-XANES spectroscopic data that document a stepwise transformation of methylmercury (MeHg) to Hg-tetraselenolate (Hg(Sec)4) and mercury selenide (HgSe) (Sec = selenocysteine). By mathematical inversion of isotopic and spectroscopic data, identical δ202Hg values for MeHg (2.69 ± 0.04‰), Hg(Sec)4 (−1.37 ± 0.06‰), and HgSe (0.18 ± 0.02‰) were determined in 23 tissues of eight birds from the Kerguelen Islands and Adélie Land (Antarctica). Isotopic differences in δ202Hg between MeHg and Hg(Sec)4 (−4.1 ± 0.1‰) reflect mass-dependent fractionation from a kinetic isotope effect due to the MeHg → Hg(Sec)4 demethylation reaction. Surprisingly, Hg(Sec)4 and HgSe differed isotopically in δ202Hg (+1.6 ± 0.1‰) and mass-independent anomalies (i.e., changes in Δ199Hg of ≤0.3‰), consistent with equilibrium isotope effects of mass-dependent and nuclear volume fractionation from Hg(Sec)4 → HgSe biomineralization. The invariance of species-specific δ202Hg values across tissues and individual birds reflects the kinetic lability of Hg-ligand bonds and tissue-specific redistribution of MeHg and inorganic Hg, likely as Hg(Sec)4. These observations provide fundamental information necessary to improve the interpretation of stable Hg isotope data and provoke a revisitation of processes governing isotopic fractionation in biota and toxicological risk assessment in wildlife.

Abstract: Most of the articles of this focus section serve as good examples in the open science domain, in which data are expected to be “findable, accessible, interoperable, and reusable” (Wilkinson et al., 2016). In many contributions, emphasis is placed on quality: as automated access to seismological archives via standardized web services emerges as the preferred user strategy, ensuring the high quality of data and metadata becomes more and more important (e.g., Büyükakpınar et al., 2021; Cambaz et al., 2021; Carrilho et al., 2021; Evangelidis et al., 2021; Mader and Ritter, 2021; Ottemöller et al., 2021; Péquegnat et al., 2021; Stammler et al., 2021; Strollo et al., 2021). Quality is especially important at a time when very large datasets are increasingly being processed routinely and “blindly” in machine‐learning approaches. The vast majority of seismological data centers already manage multisensor archives (seismometers, accelerometers, infrasound, amphibian seismological instruments, high‐rate global navigation satellite systems, etc.), and the inclusion of new types of data (e.g., rotational sensors, low‐cost instrumentation, and synthetic waveforms) in seismological archives poses new challenges and prompts for new technical solutions and standards for data archiving, metadata preparation, quality checks, data dissemination, and processing. A particular challenge over the next few years (Quinteros, Carter, et al., 2021) is the upcoming massive growth of data volume, due in particular to new instruments (large‐N experiments and distributed acoustic sensing systems) but also to increased volumes of traditional seismic data. It is expected that multisensor experiments will progressively dominate the technical and scientific discussion in geosciences in the coming decade, spurred by the societal need to develop multidisciplinary, multihazard science and research products. Joining forces and competences is therefore key to addressing future challenges: the EarthScope Consortium was recently established in the United States, and the European Plate Observing System (EPOS) was created as the framework to integrate all geoscience services in the greater European region. ORFEUS and its seismic network community strongly support the development and consolidation of EPOS by participating in the activities of its thematic core service for seismology.

Abstract: Breeding at the right time is essential for animals living in seasonal environments to ensure that energy requirements for reproduction, especially the nutritional needs for rearing offspring, coincide with peak food availability. Climate change is likely to cause modifications in the timing of maximum food availability, and organisms living in polar environments where the breeding period is heavily contracted may be particularly affected. Here we used a 26-year dataset to study the phenological response of a pagophilic species, the Snow Petrel (Pagodroma nivea), to climate change and its demographic impact. First, we investigated the trends and relationships between climate variables and hatching dates measured in three neighboring colonies. In a second step, we examined the impact of the hatching date and environmental covariates on the fledging probability. Our results showed that sea ice, a climate-related variable, showed a positive temporal trend. We found that hatching date was delayed when sea ice concentration was greater and local weather conditions were worse (i.e., increase in the number of windy days or the number of snow days). Hatching date had a negative effect on fledging probability, and fledging probability showed a bell-shaped temporal trend. We suggest that Snow Petrels can delay breeding phenology in response to environmental conditions. However, this plasticity may be limited as fledging success decreased with delayed hatching, potentially making the Snow Petrel vulnerable to a mismatch between resource availability and nutritional needs.• Timing of reproduction is essential for wild animals to ensure that reproductive requirements, including nutritional requirements for rearing offspring, coincide with peak food availability.• Climate change can affect the timing of food availability, and organisms living in polar environments, where the timing of reproduction is highly contracted, may be particularly affected. We analyzed whether a sea ice dependent species, the Snow Petrel (Pagodroma nivea), would breed earlier or later in response to climate change, as measured by changes in sea ice and weather conditions. Then, we looked at the impact that a shift in reproduction might have on breeding success.• Our results showed that hatching date was delayed when sea ice increased and local weather conditions worsened. Secondly, we showed that the shift in hatching date had a negative effect on breeding success.• Snow Petrels adjusted the onset of reproduction in response to environmental changes. However, this adjustment had limits since late reproduction likely leads to a mismatch between the availability of resources and nutritional needs, and thus to a decrease the breeding success.

Abstract: Breeding failure is expected to induce behavioural changes in central place foragers. Indeed, after a failed reproductive attempt, breeding individuals are relieved from having to return to their breeding site for reproductive duties and thus are less constrained than successful breeders in their movements during the remainder of the breeding season. Accordingly, they are expected to adjust their behaviour, travelling longer in distance and/or time to reach foraging grounds. They are also expected to use different foraging areas to decrease local intra-specific competition with successful breeders. We compared the at-sea behaviour and habitat use of successful and failed Indian yellow-nosed albatrosses nesting in Amsterdam Island, Southern Indian Ocean, during 2 chick-rearing seasons. Failed breeders exhibited the same at-sea foraging behaviour, travelling as far and as long as successful breeders. They also spent the same amount of time on their nest between at-sea trips. Nevertheless, habitat models revealed partial spatial segregation of failed breeders, which used specific foraging areas characterized by deeper and colder waters in addition to the areas they shared with successful breeders. Our study shows the importance of combining a range of analytical methods (spatial analysis, behavioural inferences with advanced movement models and habitat models) to infer the at-sea behaviour and habitat use of seabirds. It also stresses the importance of considering individual breeding status when aiming to understand the spatial distribution of individuals, especially when this information may have conservation implications.

Abstract: Conceived as a baseline for the management and conservation of the marine protected area of the French Southern Territories (réserve naturelle nationale des Terres australes françaises), the checklist of marine macroalgae of the Kerguelen Islands was updated based on an extensive review of the literature and scientific databases, from the first report of the Ross expedition, in 1840, to the most recent works. This work was also conceived as a starting point for forthcoming investigations using molecular systematics tools and for monitoring the effects of global change on sub-Antarctic marine ecosystems. After a brief history of scientific campaigns, a list of 166 species was established (103 Rhodophyta, 35 Chlorophyta and 28 Ochrophyta [Phaeophyceae]). Molecular systematics studiess have shown the existence of recurrent discrepancies between the established, morphology-based taxonomy and molecular species delimitation, calling for a revision of systematics. Nevertheless, a first analysis of biogeographical affinities of the marine flora of the Kerguelen Islands is carried out and preliminary results are partially congruent with the main regions currently recognized in the Southern Ocean suggesting the importance of long-distance dispersal to explain the observed distribution patterns.