Our ability to accurately quantify the total ice volume in glaciers and the loss of glacier volume, discharge and freshwater in response to climate change is limited by a paucity of ice thickness and bed topography observations. Consequently, glacial ice thickness is often inferred indirectly from more easily obtained surface measurements. Here, we present a simple inversion building on the assumption of perfect plasticity. In the traditional perfect-plastic approximation, the ice thickness (or bed) can be inferred from the surface elevation and yield strength. Here, we extend this to demonstrate that, provided glaciers are changing, we can simultaneously determine the yield strength and bed topography from observations of surface elevation alone. We demonstrate that the ice thicknesses and bed topographies we infer perform comparably to other inversions documented in the Ice Thickness Models Intercomparison eXperiment. Unlike other inversions, we do not require surface mass balance or glacier velocities, which can be inaccurate and difficult to obtain. Given the increasing availability of high-resolution surface elevation data, it may be possible to apply this method to glaciers worldwide to better constrain the ice thickness, bed topography and volume of glaciers globally.

Reliably identifying and understanding temporal precursors to extreme wind gusts is crucial for early warning and mitigation. This study proposes a simple data-driven approach to extract key predictors from a dataset of historical extreme European winter windstorms and derive simple equations linking these precursors to extreme gusts over land. A major challenge is the limited training data for extreme events, increasing the risk of model overfitting. Testing various mitigation strategies, we find that combining dimensionality reduction, careful cross-validation, feature selection, and a nonlinear transformation of maximum wind gusts informed by Generalized Extreme Value distributions successfully reduces overfitting. These measures yield interpretable equations that generalize across regions while maintaining satisfactory predictive skill. The discovered equations reveal the association between a steady drying low-troposphere before landfall and wind gust intensity in Northwestern Europe.

Spacecraft assembly facilities (SAFs) house clean rooms where interplanetary spacecraft are built, thereby reducing the bioburden on spacecraft to protect planetary environments from terrestrial microbes that may interfere with the search for life or disturb potential native ecosystems. The most plausible environments for living systems on celestial bodies involve brines with depressed freezing points. Here, we specifically measure the abundance of salinotolerant microbes on SAF surfaces. Most probable number analyses performed with salty liquid media were applied to washes of SAF floor wipes. Microbial abundance was measured using Salt Plains medium at low salt or supplemented with (all w/v) 10% NaCl (1.7 M; aw = 0.92), 50% MgSO4 (2.0 M as epsomite; aw = 0.94), 5% NaClO3 (0.5 M; aw = 0.98), or 5% NaClO4 (0.4 M; aw = 0.98). The abundance of salinotolerant microbes was generally 1 to 10% (102 to 104 cells m−2) of the total population of microbes observed in low-salt medium (105 cells m−2). Microbes were isolated by repetitive streak-plating of positive enrichment cultures and then characterized. All of the 38 isolates were Gram-positive bacteria, mainly spore-forming Bacillaceae, with some Staphylococcus. The isolate collection showed strong tolerance to high concentrations of NaCl (to 30%), MgSO4 (to 50%) and sucrose (to 70%). There also was substantial tolerance to pH (5 to 10) and temperature (4 to 60 °C). Taken together, these SAF isolates are polyextremophiles that are in substantial abundance in the clean rooms where spacecraft are assembled.

In discussions on European Neogene continental chronology, the Kastellios Hill section has played an important role because of the presence of strata with planktonic foraminifers and strata with mammalian remains. With the primary papers written in the 1970s and 1980s, the time is ripe for an update on age and taxonomy of the murid rodents from Kastellios Hill by comparing the fauna with time-equivalent southern and central European faunas. This comparison results in a partly revised faunal list consisting of the dominant Progonomys mixtus n. sp., the less common Cricetulodon cf. C. hartenbergeri Freudenthal, 1967 and P. cathalai Schaub, 1938, and the rare P. hispanicus Michaux, 1971 and cf. Hansdebruijnia neutra (de Bruijn, 1976). Based on the updated species list and magnetic polarity data, the most probable age of the Kastellios Hill mammal localities is 9.3–9.1 Ma (Chron C4Ar.1r, late Vallesian, MN10). The genus Hansdebruijnia is narrowed down to two species in an ancestor–descendant relationship: the ancestral type species H. neutra, which is restricted to southeastern Europe and Anatolia, and the descendant species H. magna (Sen, 1977), representing a new combination and including ‘Occitanomys alcalai’ Adrover et al., 1988 and ‘O. debruijni’ (Hordijk and de Bruijn, 2009). H. magna colonized both southeastern and southwestern Europe.

UUID: http://zoobank.org/ebe0f64c-6900-4efc-ab43-8a4045de6810

Sea ice outflow through the Transpolar Drift (TPD) is essential in Arctic sea ice loss. Twenty-four buoys deployed in the Arctic Ocean during the summer of 2021 were used to analyse sea ice kinematics and deformation across the pack ice zone (PIZ) and marginal ice zone (MIZ), mainly focusing on the TPD region. Three stages were identified as sea ice transitions from melt to growth and to melt again. In Stage 1, sea ice exhibited active internal motion, with a high deformation rate (5.7 d−1) determined using the buoy trajectory-stretching exponents. In Stage 2, ice consolidation reduced wind response and deformation rates (2.3 d−1), but still with intermittently enhanced ice deformation over 6.0 d−1 caused by severe storms. In Stage 3, the combined impacts of a super cyclone, MIZ ice and oceanic conditions, and tidal dynamics north of Svalbard remarkably altered the ice kinematic regime. Variations in sea ice kinematics along the TPD region support the MIZ definition by the threshold of certain sea ice concentration variability. This study demonstrates how seasonal transitions, spatial heterogeneities of sea ice conditions, atmospheric or oceanic forcings, and extreme cyclones collectively shape sea ice dynamics in the TPD region, amplifying its seasonal changes relative to those in the central Arctic Ocean.

The Southern Ocean, a region characterized by high nutrient levels but often low productivity, hosts dynamic picophytoplankton communities crucial for its food web. This study investigated the spatial and inter-annual variability of picophytoplankton abundances and their environmental drivers in the Indian sector of the Southern Ocean during the austral summers of 2018 and 2020. Using flow cytometry for picophytoplankton quantification and standard oceanographic methods for environmental parameters (temperature, salinity, nitrate, phosphate, silicate), we employed descriptive statistics, inferential group comparisons (t-tests, analysis of variance), principal component analysis (PCA) and principal component regression (PCR) to analyse the dataset. Our analyses revealed significant differences in picophytoplankton abundances and environmental conditions across distinct oceanic fronts, between deep chlorophyll maximum and surface depths and, notably, between the two study years. PCA identified three major environmental gradients explaining over 93.5% of the variance in temperature, salinity, nitrate, phosphate and silicate. PCR confirmed our hypothesis: the abundance and carbon biomass of picoeukaryote II (PEUK-II) picophytoplankton was statistically significant overall (F-statistic = 3.415, P = 0.0290). The model explained 24.2% of the variance in PEUK-II abundance (R2 = 0.242), indicating its sensitivity to dynamic oceanographic conditions, with PC3 (primarily representing a salinity gradient) being a significant predictor. Conversely, Prochlorococcus-like/Synechococcus picophytoplankton abundance was not statistically significant overall (F-statistic = 2.068, P = 0.124), suggesting control by other, potentially non-linear factors. These findings highlight distinct ecological strategies among picophytoplankton groups and are vital for predicting their roles in the Southern Ocean’s microbial food web amidst ongoing environmental change.

The evolution of the mandible in mammalian carnivores is influenced by ecological demands that have changed over their phylogenetic history. We combined geometric morphometrics and biomechanical analysis (including beam analysis and finite element analysis, or FEA) to assess the interaction between form and function as the mandible has adapted independently to carnivorous diets in therian clades including Metatheria, Mesonychia, “Creodonta,” and Carnivoramorpha. Our goal was to determine the relative contributions of mechanical advantage, mandibular force, and mandibular resistance to bending and torsion, to the evolution of mandibular shape in these groups, as well as whether they produce differential rates of shape evolution in the horizontal and ascending rami, which respectively are the tooth-bearing and muscle-loading parts of the structure.

We found that the ascending ramus has higher rates of evolution than the horizontal ramus, making it the more rapidly evolvable portion of the mandible. Statistical evaluation supports this interpretation, as mechanical advantage and resistance to force explain more of the variance in shape than do the beam mechanic estimates that are heavily influenced by the mandibular body. Regression analysis shows that the evolution of specialized carnivory was associated with stronger mandibles in which mandibular shape changed by shortening and thickening of the mandible, increasing the areas of muscle attachment, and increasing the carnassial blade length. Principal component analysis of mandibular shape shows that different clades in Theria have been able to fill out similar specialized carnivorous niches with similar functional metrics despite having different mandibular morphologies.

The evolutionary history of freshwater sponges (Porifera: Spongillida) in Australasia is poorly understood due to a paucity of fossils. A new genus and new species, Protooncosclera zealandiae n. gen. n. sp., family Potamolepidae, was discovered in southern New Zealand from lacustrine diatomites/spiculites of latest Oligocene–earliest Miocene of the Fossil-Lagerstätte at Foulden Maar. The fossil spicular complement is similar to that of the extant genus Oncosclera but differs from that and all other Spongillida genera by possessing a structured gemmular architecture armed by ornamented strongyles and strongyloxeas, with theca surrounded by a spicular cage of slender acanthoxeas, and a skeletal spicular complement of stout, smooth to spiny oxeas. This is the first fossil (pre-Quaternary) record of freshwater sponges from Australasia and fits into the Gondwana-like distribution of potamolepid freshwater sponges. Its discovery in a subtropical maar lake on the southwestern margin of Zealandia confirms a formerly wider geographic distribution of Potamolepidae in the Cenozoic, followed by range retractions related to post-Early Miocene climate cooling. The stratigraphic distribution of sponge remains at Foulden Maar demonstrates that sponges colonized the isolated maar lake soon after its formation, most likely by passive dispersal by water birds, and then thrived in the shallow water margins of the paleolake for ca. 130,000 years. Sponge remains, skeletal spicules and gemmules, frequently associated with coprolites indicate that sponges were consumed by one or more spongivorous taxa, presumably fish belonging to the Southern Hemisphere family Galaxiidae.

UUID: http://zoobank.org/72a81923-9766-4ae0-b980-28b2e3d98ebe

Ice sheets and glaciers flow through basal sliding and internal deformation, each governed by physical laws commonly expressed as power-law relations. These formulations include coefficients—the sliding coefficient and rate factor—whose values and units depend on the respective exponents. This dependency complicates the systematic exploration of parameter space, especially in ensemble simulations. To address this, we propose dimensionless formulations of both sliding and flow laws, in which the coefficients are of order unity and decoupled from the exponents. This separation simplifies sensitivity studies and parameter variations. The dimensionless laws are straightforward to implement in existing models; we demonstrate this with the SICOPOLIS ice-sheet model using three test simulations in an idealized set-up. These simulations illustrate that independent variation of exponents and coefficients is feasible and practical, supporting the use of dimensionless laws in efforts to better constrain ice dynamics in past and future climate scenarios.