This study presents new field and microstructural constraints into the batholith architecture and supra- to subsolidus evolution of late Variscan granitoids at Capo Vaticano Promontory, part of the ∼13 km-thick Serre Batholith in southern Italy. A field survey, assisted by petrographic analyses, produced the first geological map of the area (1:140,000 scale), detailing magmatic unit relationships and their petro-structural features. A migmatitic border zone (MBZ) marks the transition from lower-crustal paragneisses to the deepest emplaced granitoids. The oldest, deepest granitoids are strongly to moderately foliated amphibole-biotite tonalites and quartz diorites, transitioning to biotite tonalites and quartz-diorites (BT), which can be subdivided into strongly to moderately foliated (BTs) and weakly foliated to unfoliated (BTw). Clear intrusive contacts mark the passage from BTw to overlying weakly foliated-unfoliated porphyritic muscovite-biotite granodiorites and granites (PMBG). The study also revealed: a) a northern sector with a continuous batholith cross-section and b) a southern sector with an irregular distribution of the magmatic units due to post-Variscan tectonics. Microstructures document late Variscan deformation starting at suprasolidus conditions (e.g., quartz chessboard patterns and submagmatic fractures in plagioclase) and evolving through progressively high- to low-temperature subsolidus stages (e.g., feldspar bulging, quartz recrystallization, mica kinking) for all the magmatic units. Continuous supra- to subsolidus deformation associated with a well-developed fabric suggests tectonic control on the emplacement and cooling of early tonalites/quartz diorites, while the emplacement of the porphyritic granitoids has occurred during waning tectonic activity stages in the framework of the post-collisional evolution of the south-western Variscan Belt.

Sea-ice floating in the Arctic ocean is a constantly moving, growing and melting layer. The seasonal cycle of sea-ice volume has an average amplitude of $10\,000\,\mathrm{km}^3$ or 9 trillion tonnes of sea ice. The role of dynamic redistribution of sea ice is observable during winter growth by the incorporation of satellite remote sensing of ice thickness, concentration and drift. Recent advances in the processing of CryoSat-2 radar altimetry data have allowed for the retrieval of summer sea-ice thickness. This allows for a full year of a purely remote sensing-derived ice volume budget analysis.

Here, we present the closed volume budget of Arctic sea ice over the period October 2010–May 2022 revealing the key contributions to summer melt and minimum sea-ice volume and extent. We show the importance of ice drift to the inter-annual variability in Arctic sea-ice volume and the regional distribution of sea ice. The estimates of specific areas of sea-ice growth and melt provide key information on sea-ice over-production, the excess volume of ice growth compared to melt. The statistical accuracy of each key region of the Arctic is presented, revealing the current accuracy of knowledge of Arctic sea-ice volume from observational sources.

Sub-Antarctic marine life exhibits unique ecological traits and pronounced endemicity levels. Despite their ecological uniqueness and high conservation value, studies on sub-Antarctic benthic communities are scarce. Using underwater video imagery, we assessed the nearshore diversity and structure of faunal and algal communities of the Crozet archipelago along 12 scuba and remotely operated vehicle transects performed at Baie du Marin and Crique du Sphinx (Ile de la Possession). The influence of habitat types on species distribution was evaluated in relation to the setting up of submarine cables. A total of 51 faunal (mainly represented by Echinodermata and Porifera) and 14 algal (mainly represented by Rhodophyta) taxa were identified. The high habitat heterogeneity found in shallow waters (from 0 to 20 m depth) enhances the species richness and diversity, whereas deeper (> 20 m depth) areas were dominated by large sandy stretches and a lower diversity. Rocky habitats had the highest richness and diversity values, promoting local diversity. Submarine cables act as a hard substrate for species, whose suspended sections influence the composition and structure of benthic communities. This study improves our limited knowledge of benthic habitats and diversity from Crozet and constitutes a baseline for further monitoring of marine communities for conservation strategies related to this part of the French Southern Territories National Nature Reserve.

In this study the finding of the sponge Clathria (Clathria) unica in coastal waters of Mar del Plata city (38°14′24″S, 57°27′30″W), Argentina, at the formation called ‘Banco de Afuera’, is reported. This record constitutes the northernmost record of the species, which was known until the present study only from its type locality in San Antonio Oeste, Río Negro province. Additionally, the bathymetric range of the species is updated from intertidal to 20 m. Other two common sponge species, Cliona aff. celata and Spongia (Spongia) magellanica, were also recorded in this environment for the first time.

Antarctic terrestrial ecosystems, covering less than 1% of the continent, are under increasing anthropogenic threats, particularly from climate change and tourism. This study focuses on the impact of human trampling on soil microbial communities in Barrientos Island (South Shetlands archipelago), a frequently visited location. Soil samples were collected within and at the edge of two established paths representing varying levels of human disturbance. Physical and chemical analyses revealed significant differences between the paths, potentially creating anaerobic conditions favorable for specific microbial taxa. Thus, microbial communities also differed between the paths. Aerobic heterotrophic taxa were dominant in the less disturbed path, while anaerobic taxa such as Bacteroidetes vadinHA17 thrived in the more compacted path. Although alpha diversity indices did not differ, beta diversity analyses showed notable distinctions, particularly between the paths rather than trampled and untrampled areas. These findings suggest that microbial communities may recover following the stop of human activity, but also that indigenous microbial communities or other overlooked factors may be influencing the recovery potential. This study thus offers a starting point for similar research, as it highlights the need for further investigation to determine whether human trampling or other environmental factors are primarily responsible for these differences.

Although there is increasing evidence that birds have individual chemical profiles that can be used in different social contexts, partner scent recognition has only been explored in procellariiform seabirds, a group of birds known for their highly developed olfactory system. However, olfaction is not restricted to Procellariiformes, and birds with smaller olfactory bulbs can also use chemical cues in different social contexts. More evidence from different bird groups is needed to disentangle whether olfaction plays a general role in partner recognition. We performed a choice experiment to examine whether chinstrap penguins Pygoscelis antarcticus can discriminate the scent of their partner from the scent of other conspecifics. Our results do not suggest a preference of penguins for the scent of their partners. Our results highlight the need to carry out additional studies to determine the mechanisms underlying partner recognition in penguins.

Polar ecosystems are threatened by non-native plants, and this risk will increase with climate warming. Non-native plant growth depends on Antarctic environmental conditions and substrates, but these influences are poorly quantified. Under laboratory conditions we quantified the growth of Holcus lanatus, Trifolium repens and Taraxacum officinale across nine sub-Antarctic and Maritime Antarctic substrates with varying characteristics. This included, among others, variation in carbon (0.2–27.0%), nitrogen (0.03–2.1%) and phosphorus (0.04–0.54%) contents, under simulated Antarctic conditions (2°C) and a warming scenario. Legacy effects from an established non-native chironomid midge (Eretmoptera murphyi) and non-native grasses were included. H. lanatus and T. repens grew best in organic- and nutrient-rich substrates, while T. officinale growth was poorly correlated with substrate characteristics. Warming increased plant size by one to three times, but inconsistently across species and substrates, suggesting that climate change impacts on plant growth will vary across the Maritime Antarctic. A variable response was also observed in the legacy effects of E. murphyi, while non-native grasses increased H. lanatus and T. repens plant size, but not that of T. officinale. Plant growth was positively correlated with substrate organic and phosphorus content, and this information was used to trial a novel approach to identifying sites ‘at risk’ from plant invasions in the Maritime Antarctic.

Brazilian landowners are obligated to conserve a minimum percentage of native vegetation within their properties (termed a ‘legal reserve’), but non-compliance can be compensated elsewhere through a biodiversity offset. Recent changes in rules for legal reserve compensation (LRC) have increased the allowed spatial scale and softened the ecological criteria required to select properties for compensation, potentially leading to considerable biodiversity losses. In this paper, we analyse whether these rules promote the conservation of tree species on private lands through LRC in the Cerrado biome, the most biodiverse savannah in the world. We modelled the potential distribution of 126 Cerrado tree species and simulated several potential biodiversity offsets to calculate expected species losses under former and current LRC rules. Our results show that biodiversity offsets established under current and former LRC rules can lead to up to 100% tree species losses. In contrast, setting a minimum similarity threshold between watersheds can reduce median tree species loss in biodiversity offsets to as low as 3% and prevents LRC with no common species between sites. Therefore, the current rule is expected to strongly impact biodiversity in the Cerrado. Similarity in species composition between watersheds must be considered in order to implement LRC offsets that effectively conserve Cerrado biodiversity on private lands.

Silicified microfossils are reported from nine stratigraphic sections of the Ediacaran Doushantuo Formation deposited in shelf margin, slope, and basin environments in Hunan Province of South China. These microfossils include sphaeromorphic and acanthomorphic acritarchs (15 genera and 29 species, including three new acanthomorph species, Bullatosphaera? colliformis n. sp., Eotylotopalla inflata n. sp., and Verrucosphaera? undulata n. sp.), multicellular algae, tubular microfossils, and other problematic forms, representing major fossil groups similar to those from the Doushantuo Formation in more proximal facies (e.g., inner shelf and shelf lagoon). A database of the abundance and occurrences of Doushantuo acanthomorphs is assembled and analyzed using quantitative and data-visualization methods (e.g., rarefaction analysis, non-parametric multidimensional scaling, and network analysis). The results show that, at the genus and species levels, taxonomic richness of Doushantuo acanthomorphs exhibits considerable variation among facies, but this variation is largely due to sampling and taphonomic biases. The results also show that numerous acanthomorph taxa have broad facies distribution, affirming their biostratigraphic value. The analysis confirms that acanthomorphs in the Weng'an biota of shelf margin facies are composed of a mixture of Member II and Member III assemblages of shelf-lagoon facies in the Yangtze Gorges area. The study shows the biostratigraphic potential of acanthomorphs in the establishment of regional biozones using the first appearance datum of widely distributed taxa, highlighting the importance of continuing exploration of under-sampled Doushantuo sections in slope and basinal facies.

UUID: http://zoobank.org/6fc92858-4054-4117-8043-1f06cfe77155

This work provides a comprehensive examination of microplastic air pollution in Antarctica. Due to atmospheric microplastics’ emerging importance, analytical procedures and health effects are discussed. Microplastic pollution poses an increasing threat to the unique and delicate Antarctic ecosystem, potentially triggering harmful consequences not only for the local ecosystem and fauna, but also for human health and well-being, given the severe implications of microplastic pollution for global scenarios such as imminent worldwide warming and the melting of polar ice. Numerous investigations have now exposed the extent of microplastic pollution in the Antarctic and the prevalence of both nano- and microplastics in this region, a significant storehouse of the planet’s freshwater. This work also highlights the challenges of assessing the hazards that microplastics, particularly the nanoscale variants, may pose to human health and life maintenance. The results of this work suggest that global mechanisms of microplastic pollution mitigation are critical to microplastic transportation to the Antarctic reaches. This overview provides a better understanding of microplastic pollution in Antarctica while highlighting the urgency of more comprehensive research in this area to elucidate more precisely the short-, medium- and long-term effects of the arrival of these emerging contaminants in the Antarctic.

Feather stars (Echinodermata: Crinoidea) are known to host a diversified associated fauna. Surprisingly, very few accounts on the crinoid epiphytic communities from the coasts of the India are available. The present contribution reports for the first time the crinoid-associated scale worm Paradyte crinoidicola (Potts, 1910) from Gujarat coastline, India. The species has been so far recorded from the southern part of Indian subcontinent, the Lakshadweep Islands as its first record from Indian coastline. Further research and documentation of these species will contribute to enhance our understanding of the diverse associations and complex interactions within Indian marine ecosystems. This highlights the necessity for more thorough field surveys and ongoing monitoring, as the region remains surprisingly underexplored.

A specimen of Prionotus punctatus was caught in Bahía Engaño, Chubut Province, Patagonia, Argentina. This extends the known distribution by 900 km and a 5.5° further south from its previous southernmost record. This record increases the number of species of the genus Prionotus and the fish diversity of central Patagonia. The presence of P. punctatus along with other recent reports of fish of tropical and subtropical lineages in central Patagonia adds new evidence on the ongoing tropicalization of the Patagonian Sea.