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Small, disc-shaped shell beads are recorded as mortuary offerings in many Neolithic and Bronze Age burials in Southeast Asia. Yet the provenance of these artefacts is often obscure, as production processes involve the removal of diagnostic morphological features, negating taxonomic classification. Here, the authors report on the combined isotopic and morphological analysis of a subset of shell beads from the site of Ban Non Wat in north-east Thailand. In addition to identifying freshwater sources for nearly all the beads, the results suggest the presence of multiple shell production centres - each with access to distinct aqueous environments - and widespread exchange in the Bronze Age.

Changing ratios of stable carbon ( δ13C) and nitrogen ( δ15N) isotopes in consumer tissues reflect foraging patterns over time and can be used to inform studies on historically vulnerable populations. Northern fur seals (NFS; Callorhinus ursinus) at San Miguel Island (SMI), California, have been severely impacted by climate events such as El Niño and remain susceptible to future environmental disturbances, necessitating the need to further understand their foraging ecology. We analyzed sequential δ13C and δ15N values along single NFS whiskers sampled from five pups and five unrelated post-parturient females at SMI and reconstructed temporally aligned stable isotope profiles for each whisker. Pup profiles consistently showed increases in postnatal δ13C and δ15N values that likely stem from pup consumption of maternal milk and changes in maternal foraging locations after parturition. Adult female profiles indicated predominantly heterogeneous foraging strategies and minimal foraging outside the Southern California Bight. These findings provide initial characterizations of longitudinal, stable isotope-derived foraging data for NFS from SMI and offer insight into the inference of otariid foraging ecology with sequential δ13C and δ15N values.

Archaeological human skeletal remains are displayed in many museums across Thailand, under glass in exhibit halls, and as part of open-air displays where skeletons are partially excavated but remain in situ. This form of outdoor exhibit is a notable component of public archaeology initiatives and local educational outreach, but the potential long-term implications for bone preservation have raised concerns. This study investigated patterns of diagenesis at the Ban Pong Manao Archaeological Site and Community Museum in Lopburi Province, central Thailand, where some ancient skeletons are curated indoors in the on-site antiquities archive, and others are displayed outdoors in covered open-air excavation units. We applied a biogeochemical approach to investigate diagenesis, using methods from stable isotope analysis and Fourier-transformed infrared spectroscopy to assess post-excavation taphonomic processes. Results from this study revealed no statistically significant differences in values for bone collagen or bioapatite preservation indices between in situ and curated skeletons. However, we observed lower collagen yields and higher bioapatite carbonate yields among in situ skeletons that suggested processes of diagenesis may be accelerated by partial exposure in open-air display contexts. After roughly 20 years, differences between post-excavation contexts are not yet substantial but over time may increase if current taphonomic trajectories are maintained. We consider the implications and limitations of these results and examine partial excavation and exposure as simultaneously deleterious and additive in the context of cultural heritage management in Thailand. [ABSTRACT FROM AUTHOR]

This paper aims to provide the isotopic characterization of the diet consumed by people buried in a graveyard of the Imperial Rome Suburbium (1st–3rd centuries CE), where numerous children were buried. A sample of 50 human remains from Quarto Cappello del Prete was selected for carbon and nitrogen stable isotope analysis. Published data related to coeval faunal remains set the baseline of the diet. The results for humans were integrated with previously analyzed data from Quarto Cappello del Prete. The resulting sample of 71 people has been dissected for stratification according to demographics, focusing on the ability to ascertain the weaning process in children. Isotopic data are steady with an overall diet mainly based on terrestrial resources, where C3 plants played a pivotal role in the diet, though the δ13C range suggests that the foodstuff should have been heterogeneous. The remarkable amount of children allows us to evaluate the weaning process. Infants seem to be adequately weaned after 3 years, when they were considered as adults to what concerns the dietary habits. These data represent a valuable enhancement for understanding the weaning practices in ancient Rome, contributing to supporting the hypothesis about lifestyle and health in the Roman Imperial period. [ABSTRACT FROM AUTHOR]

Pathological conditions in skeletal remains, such as cribra orbitalia and porotic hyperostosis, can be caused by etiologically different forms of anemia: hereditary hemolytic anemias, iron deficiency anemias, megaloblastic anemias, etc. Though not always simple to apply, differential diagnosis of cases of anemia found in the archaeological record is essential to correlate the pathology with the wider environmental and socio-cultural context. Anthropological analysis of the skeletal sample from the archaeological site of Vetricella showed a very high prevalence of cribra orbitalia and porotic hyperostosis. The differential diagnosis between acquired and congenital anemia is essential in the study of this condition, especially considering the presence of Plasmodium falciparum in this area and its role in the possible subsequent spread of the thalassaemia gene, which was widespread until a few decades ago. Carbon and nitrogen stable isotope analysis was carried out on a large subset of the skeletal sample, including both anemic and non-anemic individuals, to investigate the nutritional patterns of the Vetricella population in order to verify whether the widespread traces of anemia might be of dietary origin. Isotope results allowed for the exclusion of the hypothesis of nutritional-deficiency anemia and supported the hypothesis of congenital anemia. [ABSTRACT FROM AUTHOR]

Corals and sponges are considered foundational species and can create biodiversity hotspots in the deep sea, yet little is known of their competitive interactions, particularly with respect to resource partitioning among benthic fauna. Here we report on the feeding ecology of deep-water corals, sponges, ascidians, and anemones from a ~ 450 m deep submarine canyon wall off Nova Scotia, Canada. Analysis of bulk stable isotopes of carbon and nitrogen confirms isotopic niche partitioning between species despite their physical proximity. Compound-specific nitrogen isotopes of amino acids (δ15N-AA) separated the taxa along continua of trophic position and benthic-pelagic coupling and resolve the conspicuously enriched bulk nitrogen patterns commonly observed in sponges. Radiocarbon dating (as Δ14C) of tissue samples, particulate organic matter (POM) and dissolved inorganic carbon (DIC) from the Scotian Slope sheds light on food provenance and distinguishes diets dominated by older, recalcitrant forms of organic matter versus surface-derived POM. Our results reveal significant differences in resource utilisation among sympatric corals, sponges, ascidians, and anemones and highlight that organisms capable of feeding on more recalcitrant resources will likely play a greater role in supporting deep-water habitats where the quality and flux of fresh POM may be diminished. [ABSTRACT FROM AUTHOR]

The Lake Huron fish community is comprised of many non-native species, including the piscivorous Pacific salmonids chinook salmon Oncorhynchus tshawtscha, coho salmon Oncorhynchus kisutch, and rainbow trout Oncorhynchus mykiss. The only abundant native piscivorous salmonid is the lake trout Salvelinus namaycush. Since 1980, there has been a steady decline in the biomass of the prey fishes these salmonids consume. Considering the collapse of alewife Alosa pseudoharengus in 2003, there has been growing concern that lake trout will be outcompeted by the non-native salmonids. Paramount to understanding this concern is determining the diet overlap between salmonids and how the overlap has shifted with changes in prey abundance. Here, stable isotope analyses (δ13C, δ15N) from lipid-extracted muscle tissues were compared among salmonids revealing large percentages of lake-wide isotopic niche overlap. Comparisons of these isotopes from salmonid scale samples taken before and after the alewife collapse revealed a shift in the diets of chinook salmon that now overlap with lake trout. Given the strong competitiveness of chinook salmon, this result is concerning for the management of the native lake trout. [ABSTRACT FROM AUTHOR]

This study examined the diet and assimilation of basal resources by the redeye piranha, Serrasalmus rhombeus, in a low-flow section of the Xingu River, Brazil. Samples of both individuals and basal resources were collected monthly from December 2020 to November 2021, encompassing a complete hydrological cycle. The stomach contents of the individuals and tissue samples of the species were submitted to stable isotope analysis for δ13C and δ15N. The species exhibited a predominantly piscivorous diet, with no observed variation in diet composition or feeding intensity across different hydrological periods. However, δ15N levels in the species varied between periods, indicating potential shifts in the availability and assimilation of basal resources during controlled flood pulses. The trophic position of the species was higher during flood periods and lower during low-water periods. Mixing models revealed the assimilation of different basal sources in each period, with the significance of terrestrial producers evident in almost all periods except during ascending. These findings are crucial for understanding the trophic dynamics of predators in flooded forests with reduced flow, highlighting the reliance of S. rhombeus on piscivory while being supported by terrestrial basal sources in its trophic chain. [ABSTRACT FROM AUTHOR]

Rationale: Compound‐specific stable isotope analysis of hydrogen (δD) and carbon (δ13C) in organic compounds is a valuable tool in biogeochemical research. A key limitation of this method is the relatively large amount of sample required to achieve desirable precision. Methods: We developed a large‐volume (20 μL) injection method that allows for high throughput analysis of less concentrated samples and tested it for δ13C and δD measurements of n‐alkanes. We also conducted a comparison of reference standards and assessed several methods to normalize and correct n‐alkane δD and δ13C measurements. Results: The mean precision of the δD method based on 233 environmental n‐alkane samples (two to three replications per sample) is 4.0‰ (1σ, estimated from the weighted mean of the pooled unbiased standard deviations) and 0.46‰ (1σ) for δ13C from 37 environmental samples (two to three replications per sample). The evaluation of reference standards shows that the use of n‐alkane standards with large offsets in δD values in adjacent n‐alkane chains can lead to biases in measurement correction. Conclusions: The large‐volume injection method shows good reproducibility of δ13C and δD measurements of n‐alkanes and reduces the required sample concentration by about 80%. We propose that for δD measurements, a reference standard set should be used in which each reference standard has a limited range of δD values and no adjacent n‐alkane chains, to minimize memory effects. [ABSTRACT FROM AUTHOR]

Rationale: The stable isotope compositions of atmospheric CO2 can provide useful insight into various geochemical processes and carbon cycles on Earth, which is critical for understanding of Earth's changing climate. Here, we present a simple and cost‐effective analytical method for the collection and measurement of carbon and oxygen isotope compositions of atmospheric CO2. Methods: Air samples of ~150 mL were collected individually or collectively using our simple active air collection system and then extracted on a vacuum purification line to remove noncondensable gases and atmospheric water vapor. The efficiency of removing atmospheric water vapor was tested by using a magnesium perchlorate desiccant trap and a dry ice/ethanol trap. Lastly, a "J‐Cut tube sealing/cracking method" was developed to store and transfer purified atmospheric CO2 to the GasBench II and CF‐IRMS system for δ13C and δ18O measurements. Results: The collective active air collection method combined with the full sample air extraction method for a 3‐min transfer time or "Full 3m TE" yields the best analytical precision of 0.07‰ (δ13C) and 0.04‰ (δ18O). Removing atmospheric water vapor from air samples is not necessary for δ13C, but essential for δ18O measurements. The J‐Cut tube sealing/cracking method shows a near 100% effectiveness for the storage and transfer of atmospheric or any CO2. Conclusions: A simple and cost‐effect method was developed for the collection, purification, storage, and isotopic analysis of indoor/outdoor atmospheric CO2 samples for general users. This method utilizes a popular headspace gas sample preparation system for CF‐IRMS and an easy‐to‐build vacuum purification line without involving complex and high‐cost devices for the preparation of atmospheric CO2. [ABSTRACT FROM AUTHOR]

Ritual and music are important approaches to convey the ethical and moral concepts in the Zhou Dynasty (1046–256 BC) in China. The ritual and music (liyue) system, therefore, was established by the Duke of Zhou to maintain social order, create and strengthen the power of the Shang royalty. The essence of the system was the division of classes. The primary objective of this study was to analyze the sacrificial animals from the Zhuolu site (40°13´N, 115°24´E) in Hebei Province, China. We summarized the characteristics of sacrificial behavior during that period by examining the types of sacrificial animals and the specific parts of their bones. Ultimately, we discussed whether these characteristics align with the established rules of the ritual and music system. In this study, excavated animal bones were subjected to species identification, surface mark recording, and carbon and nitrogen stable isotope analyses. Skeletal surface marks and stable isotope analyses indicated that there are various methods by which people access and utilize animal resources. There are various animals, including pigs, deer, hares, ring-necked pheasants, and fish, were utilized in the burials. Included in these bones are not only the left and front parts of the body, but also the right part and the hind limbs. Not only is this inconsistent with the specified combination of animal species designated for sacrifice within the ritual and music system, but it also deviates from the requirement to utilize the left and front halves of the limbs. People may have changed and reduced the use of certain sacrificial animals according to their personal preferences and needs. This may be attributed to the disintegration of the ritual system during that period. By comparing different sites, it is possible to infer that the stringent execution of rules regarding the use of animals in burial rituals was directly related to the level of ritual system development during the period to which the site is associated. [ABSTRACT FROM AUTHOR]

Nitrogen bioavailability, governed by fixation and loss processes, is crucial for oceanic productivity and global biogeochemical cycles. The key nitrogen loss organisms—denitrifiers and anaerobic ammonium-oxidizing (anammox) bacteria—remain poorly understood in deep-sea cold seeps. This study combined geochemical measurements, 15N stable isotope tracer analysis, metagenomics, metatranscriptomics, and three-dimensional protein structural simulations to explore cold-seeps nitrogen loss processes. Geochemical evidence from 359 sediment samples shows significantly higher nitrogen loss rates in cold seeps compared to typical deep-sea sediments, with nitrogen loss flux from surface sediments estimated at 4.96–7.63 Tg N yr-1 (1.65–2.54% of global marine sediment). Examination of 147 million non-redundant genes indicates a high prevalence of nitrogen loss genes, including nitrous-oxide reductase (NosZ; 6.88 genes per million reads, GPM), nitric oxide dismutase (Nod; 1.29 GPM), and hydrazine synthase (HzsA; 3.35 GPM) in surface sediments. Analysis of 3,164 metagenome-assembled genomes expands the nitrous-oxide reducers by three phyla, nitric oxide-dismutating organisms by one phylum and two orders, and anammox bacteria by ten phyla going beyond Planctomycetota. These microbes exhibit structural adaptations and complex gene cluster enabling survival in cold seeps. Cold seeps likely are previously underestimated nitrogen loss hotspots, potentially contributing notably to the global nitrogen cycle. Little is known about nitrogen loss processes in deep-sea cold seeps. Here, the authors report that cold seeps are potential hotspots of nitrogen loss, revealing high rates and a diverse range of nitrogen loss genes across multiple microbial phyla. [ABSTRACT FROM AUTHOR]

Many species establish symbiotic partnerships with different organisms to benefit energetically from living together to fit into environments, and such symbiosis is frequently found in the modern ocean as well as throughout Earth's history. For example, coral reef ecosystems represent one of the most productive and biologically diverse ecosystems in the modern ocean, which is simply explained by an assumption that many autotroph-heterotroph symbiotic species found in there increase the efficiency of trophic transfer from primary producers (i.e., algal symbionts) to primary consumers (i.e., animal hosts), and that such high efficiency may be propagated to entire food webs. However, this high efficiency has not been proved and illustrated with quantitative data in the trophic transfer of photosynthates from algal symbionts to animal hosts. In the present study, we measured the energetic balance between degradation and biomass growth, which is a major factor of the efficiency of trophic transfer, based on the analysis of stable nitrogen isotope ratios of amino acids for several species including sea anemones, stony corals, zoanthids, and soft corals, that were bred under an autotrophic condition in a laboratory aquarium. The results confirm that the symbiosis indeed provides highly effective energy transfer of algal photosynthates to animal hosts, and allow us to quantify that the energy transfer in the symbiosis increases by approximately twice of that when non-symbiotic herbivorous species feed on primary producers. These results induce a new perspective that the effective energy transfer driven by symbiosis is a critical factor controlling the development of highly productive and biologically diverse ecosystems in the modern ocean as well as throughout Earth's history. [ABSTRACT FROM AUTHOR]

Ammospiza nelsoni subvirgata (Acadian subspecies of Nelson's Sparrow) breeds in saltmarsh from northern Massachusetts to New Brunswick and eastern Quebec. In the Canadian Maritimes, this subspecies also successfully breeds in diked agricultural lands (i.e. "dikeland") that were originally created by Acadian settlers in the 1600s. Little is known about the reasons for or consequences of using dikeland for breeding. To fill this knowledge gap, we tracked male and female sparrows, and monitored nest fates in natural saltmarsh and human-made dikeland habitats. We collected fecal samples from adults and nestlings to examine which habitat type they were foraging in, and we also quantified vegetative cover. We hypothesized that flood risk in saltmarsh played an important role in the decision of A. n. subvirgata to nest in dikeland given that the saltmarsh is regularly inundated with tidal water. Based on nest monitoring, we estimated higher overall nest success in dikeland than saltmarsh. Fecal sample analysis showed distinct differences in diet between individuals using dikeland compared with saltmarsh. We also observed differences in vegetation. These results suggest that A. n. subvirgata are able to take advantage of readily available human-made habitats for breeding. With rising sea levels and increased storm events threatening coastal habitats, it is important to understand whether coastal-breeding birds can adapt to changes and what trade-offs exist for individuals who shift to alternative habitats. [ABSTRACT FROM AUTHOR]

Determining migratory connectivity is essential to understanding population dynamics and managing and conserving migratory species. Gallinago delicata (Wilson's Snipe) is a widely hunted wetland bird distributed throughout North America and parts of South America with little known regarding migratory strategy, connectivity, or population trends. Here, we used stable hydrogen isotope analysis of feathers to identify breeding areas and determine the degree of migratory mixing of 323 G. delicata harvested in Florida during the nonbreeding season. Our results demonstrate a high degree of migratory mixing between breeding and nonbreeding seasons and provide evidence that breeding birds from throughout Canada and the northwestern United States migrate to Florida. We also found evidence of long-distance migration across both latitudinal and longitudinal bands, with 104 individuals traveling from breeding grounds in western Canada or Alaska to nonbreeding habitat in Florida; the farthest-traveling individual likely migrated at least 4,270 km. Our findings highlight the crucial role of active and coordinated monitoring and management of the widely harvested G. delicata , which as long-distance migrants are disproportionately vulnerable to global environmental change. [ABSTRACT FROM AUTHOR]

Providing novel food subsidies to wildlife can influence behavior, resource use, disease dynamics, and food web interactions. Studies examining impacts of anthropogenic food have primarily occurred in urban landscapes where anthropogenic resources are consistently accessible. National parks, however, experience similar issues regarding wildlife exploiting anthropogenic food, but access to anthropogenic food is contingent on human visitation, which can fluctuate dramatically between seasons. We evaluated how fluctuating availability of anthropogenic food and demographic factors influenced the isotopic niche of Rocky Mountain Red Fox (Vulpes vulpes macroura) at the population and individual level in Grand Teton National Park, Wyoming. From 2016 to 2021, we assessed diet-related questions by collecting 55 whisker samples and 52 hair samples from 40 unique individuals and analyzed them using stable isotope analysis (δ13C and δ15N). We discovered that Rocky Mountain red foxes have a broad isotopic niche, with seasonal differences in their consumption of anthropogenic food. Contrary to our expectations, foxes demonstrated increased reliance on anthropogenic food (higher δ13C values) during winter months, whereas natural food consumption or dietary mixing was more prominent in summer months. Natural food scarcity could be driving foxes to seek out more anthropogenic food in the winter, whereas the increased abundance of natural food items in the summer could result in a lower need for foxes to supplement their diet with anthropogenic food. Adults had consistently higher δ13C values relative to juveniles, indicating either intraspecific variation in boldness or dominance leading to increased exploitation of anthropogenic food, which could be a learned behavior coinciding with habituation. Finally, we observed that increasing densities of human features within the home range of a fox was a strong predictor of anthropogenic food reliance at the individual level. Our work provided a deeper understanding of the trophic ecology of Rocky Mountain Red Fox in relation to human activity in a nature preserve, and equipped managers with insight into potential patterns associated with food-conditioned foxes. [ABSTRACT FROM AUTHOR]

We assessed the impact of a modified flood pulse on the trophic ecology of Ilisha amazonica by analyzing diet and resource assimilation through stable isotope analysis (δ13C and δ15N). Collections were conducted monthly between December 2020 and November 2021 in the Xingu River, Amazon. Stomach and muscle tissue were extracted for analysis, and both allochthonous and autochthonous resources were collected. Stomach contents of 247 specimens were analyzed and identified. The water flow regime influenced the consumption of aquatic insects, as well as the trophic niche breadth and feeding intensity of I. amazonica. Based on isotopic composition, the primary carbon sources in the species' diet originated autochthonous items, and the species exhibited a higher trophic position during the flood period. These results highlight the influence of the flood pulse, in a reduced flow environment, on the trophic dynamics of I. amazonia. Our results emphasize the importance of comprehending the interplay between consumers and resources, in areas with human influence, where impacts are practically unknown. [ABSTRACT FROM AUTHOR]

Calcite plays a pivotal role in regulating the mobility and fate of zinc (Zn) in natural environments. Despite its significance, the mechanism of Zn sorption on calcite surfaces, particularly the transitional dynamics from surface adsorption to precipitation, remains unclear. This research studied the sorption behavior of Zn on calcite across a wide range of reaction times, pH values, and Zn concentrations. The underlying sorption mechanisms were examined through a combination of Zn stable isotope measurements and X-ray absorption fine structure (XAFS) spectroscopy. At pH 6.5 and a low Zn concentration of 5 μM, the surface coverage reached 0.9 μmol/m2, accompanied by a pronounced Δ66Zn sorbed-aqueous of + 0.40 ‰, which is indicative of a tetrahedral inner-sphere surface complexation mechanism. Conversely, at pH ≥ 7.5 and a higher Zn concentration (100 μM), the surface coverage surpassed 57.6 μmol/m2, resulting in diminished Zn isotope fractionation (+0.20 ‰), suggesting the formation of hydrozincite precipitates. These results, integrated with the XAFS analysis, revealed a continuous transition from inner-sphere tetrahedral surface complexes to hydrozincite precipitates as the pH and/or Zn concentration increased. Notably, the sensitivity of Zn isotope fractionation to distinct Zn sorption mechanisms was supported by an inverse linear relationship between Zn isotope fractionation and the Zn-O bond distance. This study significantly advances our understanding of Zn sorption mechanisms on calcite by demonstrating that the surface of calcite may have catalyzed hydrozincite precipitation when the bulk solution was undersaturated with respect to hydrozincite. The synergistic application of Zn stable isotopes and XAFS spectroscopy provides a robust framework for probing metal-mineral interactions under environmentally relevant conditions. [ABSTRACT FROM AUTHOR]

Squids occur worldwide in marine ecosystems and play a major role in pelagic food webs by connecting lower and higher trophic levels. Their high feeding intensities and pronounced diel vertical migrations make squids important components of nutrient cycles in marine ecosystems. This study assessed the trophic position and nutritional ecology of a squid species assemblage in the Benguela Upwelling System (BUS) by combining stomach content, stable isotope and fatty acid trophic marker analyses. Samples were collected in the northern (nBUS) and southern (sBUS) BUS in austral spring 2021. A total of 20 squid species from eleven families were identified. Stomach content analyses showed that squid species preyed on a variety of organisms ranging from crustaceans to lanternfishes (Myctophidae) and flying squids (Ommastrephidae). Stable isotope analyses revealed significant differences in δ15N values of small squids (dorsal mantle length < 10 cm) between the two subsystems, but none in those of large squids (dorsal mantle length > 10 cm). Trophic levels ranged from 2.2 to 5.0. Isotopic niche width was widest in the families Ommastrephidae and Cranchiidae. Principal component analyses of fatty acid compositions displayed distinct clusters separating squid families and different prey taxa. This study shows that nBUS and sBUS squids exploit a large variety of pelagic prey organisms and that trophic differences are primarily dependent on squid species and size. The results emphasize the squids' importance as interlinking element in pelagic food webs and their key function in energy transfer between epi- and mesopelagic layers. [ABSTRACT FROM AUTHOR]

High-standing islands, such as Taiwan, offer unique opportunities to study soil organic carbon (SOC) dynamics due to their steep terrains, rapid erosion, and strong climatic gradients. In this study, we investigated 54 forest soil profiles across northern, central, and southern Taiwan to assess SOC inventories and turnover using stable carbon isotope (δ13C) analyses. We applied Rayleigh fractionation modeling to vertical δ13C enrichment patterns and derived the parameter β, which serves as a proxy for SOC turnover rates. Our findings reveal that SOC stocks increase notably with elevation, aligning with lower temperatures and reduced decomposition rates at higher altitudes. Conversely, mean annual precipitation (MAP) did not show a straightforward relationship with SOC stocks or β, highlighting the moderating effects of soil drainage, topography, and local hydrological conditions. Intriguingly, higher soil nitrogen levels were associated with a negative correlation to ln(β), underscoring the complex interplay between nutrient availability and SOC decomposition. Overall, temperature emerges as the dominant factor governing SOC turnover, indicating that ongoing and future warming could accelerate SOC losses, especially in cooler, high-elevation zones currently acting as stable carbon reservoirs. These insights underscore the need for models and management practices that account for intricate temperature, moisture, and nutrient controls on SOC stability, as well as the value of stable isotopic tools for evaluating soil carbon dynamics in mountainous environments. [ABSTRACT FROM AUTHOR]

The southern oceans are home to a large variety of organisms, including many endemic species. High levels of endemism are due in part to non-physical barriers limiting gene flow in marine species. The sooty albatross Phoebetria fusca is an endangered seabird breeding on seven island groups in Atlantic and Indian Oceans. We sequenced the mitochondrial control region (55 birds) and genotyped 10 microsatellite markers (88 birds) to examine the population genetics of sooty albatrosses from Tristan da Cunha and Gough Island (Atlantic Ocean), and Marion Island, Île de la Possession (Crozet) and Amsterdam Island (Indian Ocean), which together support > 99% of the global population. We also analysed the bill sulcus colouration and quantified stable isotope composition of body feathers of breeding adults from Gough and Marion Islands. Both genetic markers identified two clusters separating sooty albatrosses breeding in the Atlantic and Indian Ocean basins. Standardized colour analysis also separated populations in the two ocean basins and revealed the sulcus of sooty albatrosses on Gough Island is significantly more yellow than individuals on Marion Island. Stable isotope analysis of body feathers showed significantly higher δ13C values from Marion sooty albatrosses compared to Gough conspecifics, indicating different moulting areas. Sooty albatrosses breeding on islands in the two ocean basins differ from each other in their genetics, morphology and ecological preferences. Accordingly, it is recommended that separate conservation management plans be implemented for sooty albatrosses breeding in each ocean basin to prevent the loss of evolutionarily significant units. [ABSTRACT FROM AUTHOR]

Karst aquifers in the Mediterranean region are crucial for water supply and agriculture but are increasingly threatened by climate change and overexploitation. The Jebel Zaghouan aquifer, historically significant for supplying Carthage and Tunis, serves as the focus of this study, which aims to evaluate its availability, quality, and vulnerability to ensure its long-term sustainability. To achieve this, various methods were employed, including APLIS and COP for recharge assessment and vulnerability mapping, SPEI and SGI drought indices, and stable and radioactive isotope analysis. The findings revealed severe groundwater depletion, primarily caused by overexploitation linked to urban expansion. Minimal recharge was observed, even during wet periods. APLIS analysis indicated moderate infiltration rates, consistent with prior reservoir models and the MEDKAM map. Isotopic analysis highlighted recharge from the Atlantic and mixed rainfall, while Tritium and Carbon-14 dating showed a mix of ancient and recent water, emphasizing the aquifer's complex hydrodynamics. COP mapping classified 80% of the area as moderately vulnerable. Monitoring of nitrate levels indicated fluctuations, with peaks during wet years at Sidi Medien Spring, necessitating control measures to safeguard water quality amid agricultural activities. This study provides valuable insights into the aquifer's dynamics, guiding sustainable management and preservation efforts. [ABSTRACT FROM AUTHOR]

For species in decline or under threat, identifying and defining refuge areas that promote their persistence can inform management actions such as translocations. Here, we aimed to identify areas of ecological refuge for Anstisia alba and Anstisia vitellina, two threatened and range-restricted frog species subject to climatic and environmental stress. We quantified the extent of range decline over the last four decades, investigated the landscape-scale factors most associated with persistence of frog populations, and developed a method to identify areas with hydrological resilience. Long-term monitoring showed that the extent of occurrence of A. alba has declined by over 50% since the 1980s and has contracted from all edges of their former range. Conversely, only one A. vitellina population has become locally extinct, and the species' extent of occurrence has expanded due to conservation introductions. Intact native vegetation cover and lower fire frequency surrounding A. alba sites were the best landscape-scale predictors of population persistence. We also determined that streams within A. vitellina habitats, as well as those in the eastern area within A. alba's range, receive substantial groundwater inputs during spring and may be more resilient to hydrological change than areas with less groundwater connectivity. The important 'wet-spots' identified for A. alba and A. vitellina are also likely to be refuges for other species, providing conditions that support survival during drier and hotter conditions. [ABSTRACT FROM AUTHOR]

The Gio Linh region in Quang Tri province, Vietnam, faces pressing threats from pollution and saltwater intrusion, endangering the groundwater quality, the primary source of potable water for the local population. This study's objective is to identify and quantify groundwater recharge sources and understand the relationships between aquifers and groundwater, as well as their interactions with surface water. The ultimate aim is to develop sustainable strategies for the prudent management of this critical natural resource. The research utilized a combination of traditional methodologies and isotopic techniques to analyze spatial and temporal variations in groundwater recharge. A unique seasonal fluctuation in stable isotope composition is pivotal in comprehending groundwater characteristics, driven by temporal changes in isotopic signatures of precipitation influenced by atmospheric moisture sources along Truong Son range in Vietnam. Local rainfall is identified as the primary source of groundwater in the Gio Linh area, with an average recharge rate of (220 ± 30) mm/year. During an extended seven-month dry season, the Truc Kinh, Ha Thuong, and Kinh Mon reservoirs in the western region serve as the sole sources of groundwater recharge. Stable isotope composition analysis confirms the lack of hydraulic interaction between Holocene and Pleistocene aquifers. To ensure the sustainable utilization of groundwater in both quality and quantity, a comprehensive strategy has been devised, emphasizing source protection and the implementation of prudent exploitation measures within the study area. [ABSTRACT FROM AUTHOR]

Compound-specific stable carbon isotope analysis of amino acids (CSIA-AA) is widely used in ecological studies to analyze food-webs and is gaining use in archaeology for investigating past diets. However, its use in reconstructing breastfeeding and weaning practices is not fully understood. This study evaluates the efficacy of stable carbon isotope analysis of amino acids in early life diet reconstruction by analyzing keratin from fingernail samples of three mother-infant pairs during late gestation and early postpartum periods. Our results show that stable carbon isotope ratios (δ13C) of glycine, and to a lesser extent glutamate, effectively trace the onset of exclusive breastfeeding and the end of weaning in infants. We propose that glycine's 'conditionally essential' metabolic pathway during infancy allows it to reflect maternal glycine δ13C, indicating breastmilk consumption. Subtle changes in glutamate δ13C likely result from its 'non-essential' status. Additionally, δ13C values of glycine and glutamate indicate maternal physiological and pathological stress due to catabolic effects such as gluconeogenesis. These findings have significant implications for ecological and archaeological research using CSIA-AA for dietary reconstructions. They highlight the need to understand how metabolic pathways affecting δ13C of amino acids may change over an individual's lifespan or be altered due to various forms of stress. [ABSTRACT FROM AUTHOR]

Climate change is altering northern coastal aquatic habitats, especially in fjords. Data on current ecosystem structure and biodiversity in many northern fjord and coastal ecosystems, especially for Greenland, are lacking. We used acoustic telemetry combined with stable isotope analyses in a southwest Greenland fjord to investigate marine migrations, marine, and freshwater thermal habitat use, and the marine feeding habits of 80 acoustically tagged Arctic charr over one year. During summer, most Arctic charr occupied the inner fjord. Models of Arctic charr thermal habitat use suggested higher experienced water temperatures in the inner compared to outer fjord (estimated 1.59 °C difference) during tagged charr mean 70-day (SD = 14 days) residencies. During February and March, non-migratory individuals used warmer waters (+0.56 °C higher) than fish that ultimately migrated to sea, suggesting that over-wintering habitat use patterns influenced migration tactics. Stable isotope mixing model analysis indicated that Arctic charr fed mainly on capelin, marine gammarids, and three-spine sticklebacks. The results provide a contemporary baseline for assessing predictions of potential changes in the ecology of Arctic charr in SW Greenland fjords. [ABSTRACT FROM AUTHOR]

Lake restoration by biomanipulation or phosphorus fixation has been commonly applied methods to improve the ecological status of lakes. However, the effects of lake restoration on food-web dynamics are still poorly understood, especially when biomanipulation and nutrient fixation are used simultaneously. This study investigated the combined effects of a 70% fish removal (mainly roach (Rutilus rutilus Linnaeus, 1758) and bream (Abramis brama Linnaeus, 1758) and Phoslock® treatment on fish trophic ecology in Lyngsø (area: 9.6 ha, mean depth: 2.6 m), Denmark. The lake restoration resulted in decreased nutrient levels, increased water clarity, and increased coverage of more structurally complex submerged macrophytes. Following lake restoration, significant changes in diets of the dominant fish species were observed. Stomach content analyses of roach and perch (Perca fluviatilis Linnaeus, 1758) revealed significantly reduced detritus utilization and increased foraging on macrophytes and macrophyte living invertebrates. Results from stable isotope mixing models indicated a shift from littoral benthic to more pelagic food resources by the dominant fish species. Our findings provide further evidence that lake restorations can lead to substantial changes in lake food webs and fish communities, thereby potentially facilitating a shift toward an ecological state resembling the pristine reference state, less influenced by anthropogenic factors. [ABSTRACT FROM AUTHOR]

Much has been learned about Mars through data returned from space missions and analyses of martian meteorites. There are, however, many questions still outstanding which cannot currently be answered--including the issue of whether there is, or was, life on Mars. The return of a cache of samples--including of the atmosphere--from separate locations in Jezero Crater and with differing petrogeneses will provide the international community with the opportunity to explore part of the evolutionary history of Mars in great detail. Specifically, measurements of the isotopic compositions of the light elements H, C, N, O, Cl, and S can be used to follow how volatile species cycle through the different martian volatile reservoirs (atmosphere, lithosphere, cryosphere, and hydrosphere). Measurement of isotopic fractionation enables inference of the environmental conditions (e.g., temperature, water/rock ratio) under which fractionation occurred. Knowing the contextual relationship of the materials to their geological settings, coupled with precise compositional measurements will enable a more thorough understanding of martian volatile history and allow a picture to be constructed of water and climate on Mars as represented at Jezero Crater. [ABSTRACT FROM AUTHOR]

Although the detrimental ecological and economic effects of introducing freshwater fish species have been extensively documented, non-native freshwater fishes continue to be introduced in large numbers globally to enhance fisheries and aquaculture. In Turkey, stocking of common carp Cyprinus carpio is practised to provide food security for people and job security for artisanal fishers, resulting in a country-wide distribution. These stockings, however, increase the risk of accidental introductions and have led to introductions and subsequent invasions of gibel carp Carassius gibelio, a globally invasive and highly detrimental fish species. Here, we assessed the growth types, body conditions and trophic interactions via bulk carbon and nitrogen stable isotope analysis of common and gibel carp in both natural and artificial water bodies in Turkey. The results indicated that common and gibel carp express similar growth types and body conditions in all waters and have similar trophic ecologies. This leads to substantial trophic niche overlaps in waters where they co-occur, with the potential for strong interspecific competition. Considering the ongoing stocking of common carp for fishery enhancement, we recommend to specifically target these stockings in waters where gibel carp has already become invasive. Our findings, indeed, suggest that common carp releases have the potential to hamper invasive gibel carp populations by increasing the competitive interactions between the two species. [ABSTRACT FROM AUTHOR]

Black sea bass (Centropristis striata) feed on epibenthic prey, particularly decapods, and become more piscivorous as they grow larger, a trend that has energetic consequences for growth. In the coming decades, construction of wind energy systems will expose black sea bass to a large-scale manipulation of continental shelf habitats in the northeastern United States. In this study, we tested the effects of habitat type (natural versus artificial reef habitats) on size, age, growth, diet, and trophic dynamics of black sea bass, using 407 specimens collected with rod-and-reel gear near Ocean City, Maryland, in 2016 and 2018. No significant differences in fish length, age, size at age, or diet are attributable to habitat. The stable isotope composition (δ13C and δ15N) in samples of 3 tissue types (liver, muscle, and mucus) vary significantly by habitat except for δ15N values in mucus samples. Across tissue type, δ13C values are higher for fish at artificial habitats, indicating more littoral than pelagic feeding. We conclude that, although both types of reef habitats are ecologically equivalent as a source of growth and diet for black sea bass, the differences in stable isotope signatures indicate functional differences in system energy flow that should be investigated further in this and other marine species that will be affected by offshore wind energy development. [ABSTRACT FROM AUTHOR]

Controversy exists as to whether the Pleistocene vegetation in northern Sundaland was dominated by lowland tropical grasslands or rainforests, due to limited palaeoecological evidence recorded from the region. We describe a new Pleistocene large mammal fauna from Tham Kra Duk, a cave in the Tham Phedan mountain, Nakhon Si Thammarat Province in Peninsular Thailand, with emphasis on its palaeoecological and palaeoenvironmental investigations using the stable isotope analysis of mammalian tooth enamel. The fossil site has yielded at least nine mammalian taxa almost comparable to late middle to latest Pleistocene faunas in the mainland, thus suggesting the same biogeographic mammal elements with a range extension south of the Kra Isthmus. The stable isotope results indicate that mixed woodland to grassland ecosystems were dominated by C4 vegetation in the area. This supports the assumption that the expansion of Pleistocene tropical savanna ecosystems might have held the key to facilitating the southward distribution range of grazing mammals such as gaurs and Himalayan gorals into the Thai-Malay Peninsula. The presence of the Tham Kra Duk fauna was probably linked to some major biogeographic events of Pleistocene hominin and mammal migration through the land-bridge peninsula into the islands of Southeast Asia during a period of glaciation. [ABSTRACT FROM AUTHOR]

This article presents data from the stable isotope analysis of marble from five fragments of sculpture and a massive base that together are said to comprise the remains of the statue on Delos known as the Naxian Colossus. This key work in the early history of monumental Greek marble sculpture has attracted the attention of travelers since the 15th century (Buondelmonti, Cyriacus of Ancona). Plutarch's testimony that the great andrias of the Naxians was knocked down by the bronze palm tree of Nicias in a storm promoted the belief that all or some of the pieces identified with the colossus belonged to a later replacement for the original Archaic-period statue (dated ca. 600 BCE). The data from stable isotope analyses, in combination with the evidence from a recent analysis of style and proportions, now points to the conclusion that the fragments and base likely belong to at least three different archaic colossal statues. We explore the present limits in our interpretation of marble isotope analyses. We argue that this evidence is currently the best available means of understanding the highly debated inscription on the east side of the base: "I am of the same stone, statue and base." 1 [ABSTRACT FROM AUTHOR]

According to European reports, the population of Anguilla anguilla has declined to unsafe biological limits in most areas and current fisheries are unsustainable. Indeed, the European eel has been listed as a critically endangered species since the 1970s and has been on the IUCN Red List of Threatened Species since 2010. Glass eel fisheries in Europe are very limited, but illegal catches and international parallel trade are major threats to eel stocks due to their high commercial value. The main hypothesis of this study is that glass eels from each estuary have unique chemical profiles according to the ecological quality of the habitat. These unique chemical fingerprints were assessed using Chemical Integrating Approaches (CIA) based on multi-element (macro, trace and ultra-trace metals), global metabolome and stable isotope analyses. Thus, CIA are intended to be an effective chemical "weapon" to (i) fingerprint wild glass eels; (ii) fingerprint captive glass eels; (iii) authenticate and trace glass eels; and (iv) combat the illegal trade in juvenile European eels. The results of this study showed that Zn and Ni can fingerprint the chemical profiles of wild and captive glass eels and their geographical origin. In the same vein, metabolomes such as Butyric acid 4-vinylphenyl ester, N-(3-carboxypropanoyl)-Met, 2-(4-Methylphenyl)acetamide, N-formyl-glutamic acid, 3-Hydroxy-2-(3-methylbutanoylamino)propanoic acid, 4-Dodecylbenzenesulfonic Acid, Arginine and Pyrazole and the stable isotope 15N show potential as a chemical tools for glass eel traceability. [ABSTRACT FROM AUTHOR]

This article presents the results of oxygen stable isotope analysis on eastern oyster (Crassostrea virginica) samples (n = 25) from a Mission-Era (ca. AD 1565–1680) site, Pueblo Santa Catalina de Guale, on St. Catherines Island, GA. Stable isotope analysis was used to assess the seasonality of oyster harvesting on St. Catherines Island during the Mission Era to better understand how Spanish colonization and the Catholic mission system may have impacted Guale foodways. Five eastern oyster left valves were sampled from each known neighborhood of Pueblo Santa Catalina de Guale. Existing data regarding the seasonality of pre-colonial mollusk collection on St. Catherines Island and elsewhere in the coastal Southeast are discussed in conversation with the results of this analysis. This work indicates that Guale residents of St. Catherines Island during the Mission Era were harvesting oysters most intensely during cooler months. This pattern is consistent with estimates of pre-colonial shellfishing seasonality across the region and may even represent a modest increase in the seasonal constriction of shellfishing when compared to data from the preceding period. Salinity estimates based on the isotope data also suggest Guale people during the Mission Era were collecting from a comparatively narrower range of estuarine habitats. We argue that these subtle shifts are a consequence of the reorganization of Guale labor associated with missionization. [ABSTRACT FROM AUTHOR]

This study is based on stable isotope analysis of a rich ammonite assemblage from the Sogukcam Formation, which is widely exposed in Yesilbaglar (Olur‐Erzurum, NE Türkiye). The presence of ammonid, planktic, and benthic foraminifers in the marine sediments suggests that they are from the early Cretaceous period. The late Valanginian‐early Aptian‐rich ammonite assemblage includes the following genera and species: Acrioceras sp., Barremites difficilis, Barremites sp., Crioceratites duvalii, Crioceratites sp., Deshayesites aff. dechyi, Deshayesites sp.1, Deshayesites sp.2, Deshayesites sp.3, Deshayesites sp., Dufrenoyia cf. dufrenoyi, Dufrenoyia cf. furcata, Dufrenoyia sp., Hemihoplites sp., Heteroceras sp., Neocomites sp., Phyllopachyceras infundibulum, Protetragonites cf. quadrisulcatus, Protetragonites sp., Ptychoceras sp., Turkmeniceras cf. geokerense, and Turkmeniceras sp. This assemblage suggests that the Sogukcam Formation's deeper facies formed in the late Valanginian to early Aptian period. Fossils and δ18O data show normal paleosalinity levels. During the late Valanginian‐early Aptian period, δ18O values ranged from −3.67‰ to −2.24‰, with paleotemperatures ranging from 21.3°C to 27.9°C. δ13C positive values range from +0.65‰ to +2.86‰. δ13C isotope data show the oxygen minimum zone (OMZ) and changes in sea level and productivity. The presence of planktonic foraminifera and the ammonite assemblage indicates that the formation was deposited in warm subtropical waters ranging from the outer shelf to the open sea. [ABSTRACT FROM AUTHOR]

Opsariichthys uncirostris uncirostris (Hasu fish), a vulnerable potamodromous fish, is the only piscivorous cyprinid fish in Japan and endemic as a subspecies to Lake Biwa. The species population is on a continued decline for the past 70 years. This study aimed at developing a portfolio on the species during its reproductive migration to Shiotsuo River, a Lake Biwa tributary, by using a combination of biometric measurements and stable isotope ratios in its tissues. Hasu fish were collected monthly, from May to September 2019, using cast nets. The biometric measurements: wet weight, standard length, gonad weight and gut content were collected and used to calculate the gonado-somatic index (GSI) and Fulton's condition constant (K) and determine the feeding habits of Hasu fish. Carbon and nitrogen isotope ratios (δ13C and δ15N) in slow-changing muscle and fast-changing mucus tissues of Hasu fish were also used to determine recent diet change. At the beginning of the reproductive season, fewer females than males were caught; however, the number of females increased as the season progressed. On average, males were larger than females. Migrating individuals were healthy (K > 1) and over 37% larger in length than those in the 1960s. Gut content analysis revealed, for the first time, Hasu fish feeding in the rivers, primarily on Ayu fish, during the reproductive migration. δ13C and δ15N in muscle and mucus indicated a recent change in diet, i.e., from Lake Biwa to Shiotsuo River, with differences in the onset of feeding (and consequently upstream migration) between sexes and individuals. For the effective conservation of Hasu fish in the other tributaries where Ayu fish traps block other fishes' migration, we recommend having the rivers open from June to September to cover its variable timing in the recruitment of reproductive individuals. [ABSTRACT FROM AUTHOR]