Leopard seals (Hydrurga leptonyx) lead solitary lives, mainly associated with sea ice, and they are parasitized by the sucking louse Antarctophthirus ogmorhini, one of the few known marine insects and probably the only group adapted to survive in deep-ocean environments. A challenge for seal lice is that their eggs do not survive underwater, requiring them to complete their life cycle during the host’s reproductive or moulting season. We investigated the infestation parameters of A. ogmorhini in leopard seals on the Danco Coast, Antarctic Peninsula, estimating prevalence and mean abundance, comparing by sex, age class and interannual variability and determining the relationship between these parameters and the body condition of the seals. Over four field seasons (2014, 2015, 2019 and 2020), we collected data from 50 seals: 12 females and 38 males, including 47 adults and 3 juveniles. The overall prevalence (14%) was the lowest recorded for an Antarctic seal, with higher rates in juveniles (33.3%) than adults (12.8%) and in males (15.8%) compared with females (8.3%). Generalized linear models analysis, considering body condition and interannual variability, did not reveal a strong correlation between body condition and lice infestation. Although no strong correlation was found, there is some indication that seals in poorer condition may be more heavily infested.

Submarine melting is one of the major mechanisms of ice loss from marine-terminating glaciers and ice shelves, but its contribution is yet to be fully understood. Here, we demonstrate the feasibility of monitoring melting using passive underwater acoustics, by sensing the loud crackling sound produced during melting due to the release of pressurised ice-trapped bubbles. We profile the acoustic field in glacial bays in Svalbard using a hydrophone array and show that the sound level in the bay contains clues on the melt activity. The sound level’s interpretation is hindered by its spatial variability, which we suppress using a model of melt-induced acoustic activity. Thereby, we show that the sound generated at the glacier terminus is correlated with the ablation rate at the calving glacier front and the water temperature and thus linked to the melt rate. This marks a step forward in using passive acoustics to monitor submarine melt, paving the way for an autonomous, long-term, large-scale monitoring tool providing data that can inform assessments and simulations of ice sheet loss and sea level rise.

While geological and paleoanthropological studies at Laetoli have focused on the relatively fossiliferous Ndolanya and Laetolil beds, Laetoli’s younger Naibadad and Olpiro beds provide an important record of Pleistocene volcanism, tectonics, and landscape evolution in northern Tanzania. This study documents the mineralogical and geochemical compositions of their tephra using EPMA of glass and phenocrysts, and their ages using 40Ar/39Ar geochronology. Naibadad Beds tephra is rhyolitic or trachytic, compositionally distinct from the underlying Ndolanya and overlying Olpiro beds in their mineral assemblages and glass and phenocryst compositions. The Naibadad Beds can be divided into chronostratigraphic clusters as follows: Lower (2.189–2.154 Ma), Middle (2.115–2.104 Ma), and Upper (2.036–2.004 Ma). Most Naibadad Beds tephra could not be compositionally differentiated, although the basal Naibadad Beds tuff is unique in having both trachytic glass and andradite garnet. The uppermost Naibadad Beds tuff at Locality 23 has rhyolitic glass and aenigmatite like Olduvai Gorge’s Naabi ignimbrite and a similar age (2.033 Ma and 2.004 Ma, respectively), although they differ in feldspar and augite composition and are likely not from the same eruption. The lack of direct correlatives between Olduvai and Laetoli, which both derived tephra from Ngorongoro over the same time interval, is likely explained by paleotopography.

This study marks the first update on Malaysia’s marine tardigrades after more than 50 years, presenting both the discovery of a new species, Batillipes malaysianus sp. nov., and a new record, Batillipes rotundiculus. The specimens were collected from the intertidal zone at Pantai Pancur Hitam, Labuan, Malaysia, during two separate sampling efforts. Despite extensive sampling, the density of marine tardigrades in the area was found to be exceptionally low, with only a single specimen of B. malaysianus sp. nov. and a limited number of other Batillipes individuals collected. The new species, B. malaysianus sp. nov., is distinguished by unique morphological features, including setae scattered across the ventral cuticle – a trait not observed in any other species of the genus – and constricted primary clavae, a characteristic absent in other species of the B1 toe arrangement group. Additionally, B. rotundiculus represents the first confirmed record of this species in Malaysia, expanding its known distribution. This study also updates the global species count of Batillipes to 42, incorporating recent taxonomic changes and this new addition. An updated dichotomous key for the genus is provided, incorporating all species described to date. These findings underscore the importance of exploring understudied marine habitats and highlight the potential for discovering more tardigrade species in Malaysia.

We evaluated the physiological condition of the Pygoscelis penguins at Isla 25 de Mayo/King George Island (Antarctica Peninsula). Samples were collected from adults and chicks of Adélie (Pygoscelis adeliae, n = 20 each), gentoo (Pygoscelis papua, n = 20 chicks and n = 24 adults) and chinstrap penguins (Pygoscelis antarcticus, n = 18 each). We analysed haematological and biochemical parameters as indicators of health, immune response and nutrition. Gentoo penguin chicks exhibited higher haematocrits, indicating development linked to erythropoiesis and reticulocyte release from bone marrow or signalling dehydration related to fasting periods in chicks. Adélie penguins had increased total leukocyte counts, basophils and eosinophils, whereas gentoo penguins showed elevated heterophils and decreased lymphocytes, resulting in a higher heterophil/lymphocyte ratio stress index, possibly due to the impact of human activities. Chinstrap penguins from a remote area exhibited the lowest heterophil/lymphocyte ratio values. Adélie penguins showed more erythrocytic nuclear abnormalities, indicating sensitivity to environmental deterioration due to human impacts. The biochemical results were less consistent; Adélie penguins had higher cholesterol, whereas gentoo penguins had elevated triglycerides. Gentoo penguins showed dietary adaptability based on prey availability in this area. Our findings highlight the vulnerability of Adélie penguins and contribute to a 20 year physiological monitoring dataset for Antarctic penguins, which will aid future comparative studies.

The numerous ephemeral glacial meltwater streams that flow during the summer in the McMurdo Dry Valleys of South Victoria Land, Antarctica, provide habitats for microbial mats. One of the common mat types is composed of Chlorophyta (colloquially known as a ‘green mat’ due to its colour). While the presence of these mats is regularly monitored, their taxonomic makeup is still under investigation. Using 18S rRNA gene sequencing, the composition of the chlorophyte-dense mats from between rocks and in the main channel from several streams across two valleys was examined. Samples were maintained in native stream water, and select samples from representative locations were transferred to Bristol Medium. The appearance of other eukaryotic species - diatoms and tardigrades - in these green mats completed this integrated study. The results show that the relative abundance of Chlorophyta was significantly increased with the introduction of inorganic nitrogen from Bristol Medium. Chlorophyte taxa in the Hazenia and Pleurastrum genera dominated the samples across both sample types (rock or exposed) and treatments (Antarctic water or Bristol Medium). Furthermore, a reduction in overall sample diversity was observed in samples in Bristol Medium, suggesting preferential nitrogen utilization by these chlorophytes.

Funisia dorothea Droser in Droser and Gehling, 2008 is an inferred metazoan-grade tubular organism, endemic to the Ediacara Member, Rawnsley Quartzite, of South Australia (~555–550 Myr), which is characterized by a hollow, elongate body constructed of uniserially repeating modular elements and is one of the most abundantly reported members of the Ediacara biota. Thus, Funisia Droser in Droser and Gehling, 2008 has broad significance for developing understanding of the Ediacara biota and provides a large dataset for testing hypotheses on the biological traits of Ediacaran tubular organisms. This study investigates size changes in Funisia’s modular elements to provide further insight into the paleobiology of this organism through the development of a holistic growth model. Results demonstrate that growth in Funisia was highly regulated to maintain uniform modular element width along the length of an individual and, thereby, an overall cylindrical form despite increasing module width throughout ontogeny. The growth model proposed here is compared with the pre-established growth model for another modular Ediacaran tubular organism, Wutubus annularis Chen et al., 2014, demonstrating that the two taxa had distinct growth patterns and disparate autecological strategies, despite a shared constructional morphology.

Fe-dominant cordierite, the mineral sekaninaite, is relatively rare in calc-alkaline volcanic rocks, with only a handful of recorded localities. The compositionally zoned phenocrysts in the Late Devonian Rubicon Rhyolite in central Victoria, Australia are the most Fe-rich known, with core compositions having Mg# of 10–30. Similar cordierite–sekaninaite (Crd–Skn) phenocrysts occur in: rhyolites and rhyodacites from San Vincenzo and Roccastrada in Tuscany; on Lipari Island in Italy; in the Nefza province in northern Tunisia; and in a newly discovered Devonian rhyolite at Arthurs Seat, Victoria. All show well-developed sector twinning in response to structural ordering during cooling. The Victorian sekaninaite crystals all show strong zonation from Fe-rich cores to rims richer in Mg, i.e. reverse zoning. In contrast, the Italian and Tunisian examples have relatively weak normal zoning. In the Roccastrada and Lipari rocks, a second type of Crd–Skn occurs as turbid fragments and as groundmass crystals, with the latter showing reverse zoning. Reverse zoning in the Rubicon and Arthurs Seat rhyolite phenocrysts and the Lipari groundmass crystals is attributed to the reheating of their host magmas due to interaction, such as mixing, with a higher-temperature magmas prior to eruption. The ranges of Crd–Skn compositions in all volcanic rocks bear no systematic relationship to the bulk compositions of their host rocks. Assuming that the whole-rock compositions approximate the original magmatic liquids, and an initial H2O content of 5 wt.% throughout, enabled a comparison to be made between the relative P–T conditions of most occurrences, apart from Lipari. Results suggest that the Rubicon Rhyolite had the lowest P–T conditions with Roccastrada next, and San Vincenzo the highest. It appears that sekaninaite might be stable in silicic volcanic magmas over a wide range of melt compositions, pressures and temperatures but is favoured for low-Mg# bulk compositions at low P and low T.