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Although dietary studies have provided important insights into the causes and ramifications of diet variation for the southern elephant seal (SES) (Mirounga leonina), adult males are comparatively underrepresented within that literature. Individual males can vary morphologically as well as behaviourally, leading to differences in their life history trajectories and outcomes. Therefore, to improve our understanding of the male diet, we sought to determine the degree of dietary variation between as well as within individuals from the West Antarctic Peninsula. Secondly, we investigated whether individual morphological traits, seasonality, and year influenced their dietary variation. Whiskers were sampled from 31 adult male seals and used to measure the bulk stable isotope nitrogen (δ15N). We sequentially segmented each whisker to create a time series of datapoints for each individual, allowing us to compare δ15N variation within each seal as well as assess variation between the seals. We then investigated the relationships between male dietary variation and body length, girth, season, and year. We found that adult male SESs maintained an extremely specialised diet. Variation between individuals was strongly correlated with their body size, with larger seals feeding higher up the trophic web. Interestingly, seasonality and year both influenced variation within the seals’ diets, but only year was seen to influence the variability between seals. We discuss the possible causes and ramifications of dietary specialisation for the SES and highlight the need for combined tracking and stable isotope investigations to improve our understanding of the ontogeny of the seals’ dietary specialisation.

International audience; High spatial and temporal resolution hydrographic data collected by Southern Elephant Seals (Mirounga leonina, SESs) and satellite remote sensing data allow a detailed oceanographic description of the Argentine Continental Shelf (ACS). In-situ data were obtained from the CTD (Conductivity, Temperature, and Depth), accelerometer, and hydrophone sensors attached to five SESs that crossed the ACS between the 17th and 31st of October 2019. The analysis of the temperature (T) and salinity (S) along the trajectories allowed us to identify two different regions: north and south of 42°S. Satellite Sea Surface Temperature (SST) data suggests that north of 42°S, warm waters are coming from the San Matias Gulf (SMG). The high spatio-temporal resolution of the in-situ data shows regions with intense gradients along the T and S sections that were associated with a seasonal front that develops north of Península Valdés in winter due to the entrance of cold and fresh water to the SMG. The speed of the SESs is correlated with tidal currents in the coastal portion of the northern region, which is in good agreement with the macrotidal regime observed. A large number of Prey Catch Attempts (PCA), a measure obtained from the accelerometer sensor, indicates that SESs also feed in this region, contradicting suggestions from previous works. The analysis of wind intensity estimated from acoustic sensors allowed us to rule out the local wind as the cause of fast thermocline breakups observed along the SESs trajectories. Finally, we show that the maximum depth reached by the elephant seals can be used to detect errors in the bathymetry charts.

To understand the response of freshwater organisms to rising environmental salinity, it is essential to investigate their osmo-ionic regulatory physiology. Our laboratory experiment investigated the transfer of Palaemon argentinus (Nobili, 1901) from 2‰ (control condition) to concentrated salinity (15 and 25‰) for short- (6 h), medium- (48 h), and long-term (>504 h) acclimation periods. We measured relevant parameters in the shrimp’s haemolymph, the time course of the response of branchial V–H+–ATPase (VHA), Na+, K+–ATPase (NKA), carbonic anhydrase (CA) activity, and muscle water content. Upon prolonged acclimation to 15‰ (hyper-regulating condition), shrimp reached a new steady state of haemolymph osmolality by tightly adjusting ion concentrations to levels higher than the external medium. While NKA and CA activities recovered their pre-transfer levels, the downregulation of VHA suggests other functions rather than ion uptake after prolonged acclimation to 15‰. The activity of the three transport-related enzymes remained almost unchanged at the highest salinity (isosmotic condition), leading to increasing osmotic pressure and ion concentration after prolonged acclimation to 25‰. Although the freshwater shrimp studied here retains a certain degree of tolerance to high salinity, a common trait in palaemonid shrimps, our results highlight that 25‰ represents a significant hypertonic challenge for this species.

Mineral dust aerosol concentrations in the atmosphere varied greatly on glacial–interglacial timescales. The greatest changes in global dust activity occurred in response to changes in orbital parameters (which affect dust emission intensity through glacial activity) and the lifetime of dust in the atmosphere (caused by changes in the global hydrological cycle). Long-term changes in the surface dust deposition rate are registered in geological archives such as loess, peats, lakes, marine sediments, and ice. Data provided by these archives are crucial for guiding simulations of dust and for better understanding the natural global dust cycle. However, the methods employed to derive paleo-dust deposition rates differ markedly between archives and are subject to different sources of uncertainty. Here, we present Paleo±Dust, an updated compilation of bulk and <10 µm paleo-dust deposition rates with quantitative 1σ uncertainties that are inter-comparable among archive types. Paleo±Dust incorporates a total of 285 pre-industrial Holocene (pi-HOL) and 209 Last Glacial Maximum (LGM) dust flux constraints from studies published until December 2022, including, for the first time, peat records. We also recalculate previously published dust fluxes to exclude data from the last deglaciation and thus obtain more representative constraints for the last pre-industrial interglacial and glacial end-member climate states. Based on Paleo±Dust, the global LGM:pi-HOL ratio of <10 µm dust deposition rates is 3.1 ± 0.7 (1σ). We expect Paleo±Dust to be of use for future paleoclimate dust studies and simulations using Earth system models of high to intermediate complexity. Paleo±Dust is publicly accessible at https://doi.org/10.1594/PANGAEA.962969 (Cosentino et al., 2024).

Abstract Conflicting results remain on how climate change affects the biological performance of different marine taxa, hindering our capacity to predict the future state of marine ecosystems. Using a novel meta-analytical approach, we tested for directional changes and deviations across biological responses of fish and invertebrates from exposure to warming (OW), acidification (OA), and their combination. In addition to the established effects of climate change on calcification, survival and metabolism, we found deviations in the physiology, reproduction, behavior, and development of fish and invertebrates, resulting in a doubling of responses significantly affected when compared to directional changes. Widespread deviations of responses were detected even under moderate (IPCC RCP6-level) OW and OA for 2100, while directional changes were mostly limited to more severe (RCP 8.5) exposures. Because such deviations may result in ecological shifts impacting ecosystem structure and processes, our results suggest that OW and OA will likely have stronger impacts than those previously predicted based on directional changes alone.

We introduce version 2.0 of $Z'$-explorer, a software tool which provides a simple, fast and user-friendly test of models with an extra $U(1)$ gauge boson ($Z'$) against experimental LHC results. The main novelty of the second version is the inclusion of missing energy searches, as the first version only included final states into SM particles. Hence $Z'$-explorer 2.0 is able to test dark matter models where the $Z'$ acts as an s-channel mediator between the Standard Model and the dark sector, a widespread benchmark employed by the ATLAS and CMS experimental collaborations. To this end, we perform here the first public reinterpretation of the most recent ATLAS mono-jet search with 139 fb$^{-1}$. In addition, the corresponding searches in the visible final states have also been updated. We illustrate the power of our code by re-obtaining public plots, and also showing novel results. In particular, we study the cases where the $Z'$ couples strongly to top quarks (top-philic), where dark matter couples with a mixture of vector and axial-vector couplings, and also perform a scan in the parameter space of a string inspired Stückelberg model. $Z'$-explorer 2.0 is publicly available on GitHub. Computer physics communications 288, 108729 (2023). doi:10.1016/j.cpc.2023.108729 Published by North Holland Publ. Co., Amsterdam