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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.

Free-roaming cats (Felis catus) are considered one of the most damaging invasive vertebrate pests in natural areas globally and are a major source of mortality for small animals in suburban and urban environments. Domestic cats are also considered to be a nuisance and a source of disease transmission to pet cats and to wildlife. Historically, the most common method of managing free-roaming cats has been euthanasia, but non-lethal approaches, such as trap-neuter-return (TNR), are increasing in popularity with the public. TNR-sterilized cats, subsidized by regular human feeding, remain in the environment and continue to prey upon wildlife and to be a source of disease and nuisance. However, the extent to which these cats depend on wild-caught prey vs. provisioned pet food is not clear. Moreover, if TNR colonies are located in areas of intensive human development, predation by these cats may be focused on commensal or widespread prey species rather than native species of conservation concern. Management of free-roaming cats aimed at protecting wildlife at the urban-wildland interface requires knowledge of the diet of cats across a gradient of land-use, from rural and natural open space to intensively developed suburban and urban areas. Our aim is to use stable isotope analysis to determine the diet of free-roaming cats in southern California, using ear tissue collected during TNR sterilization procedures. We will compare stable carbon and nitrogen isotope values of free-roaming cats, collected across a gradient of anthropogenic land use, to isotope values of potential prey and anthropogenic foods to determine whether they consume native or commensal prey, or rely on human-provisioned food. To date we have collected more than 300 cat ear tissue samples from veterinary clinics that perform spay and neuter procedures to support TNR programs in the greater Los Angeles metropolitan area. We have also coordinated with vector control agencies and wildlife rehabilitators in the region to collect samples of local commensal and non-commensal bird species, as well as collected samples of commercial pet food. Samples will be dried and homog­enized and sent to UC Davis Stable Isotope Facility for analysis using mass spectrometry. When results are received, we will use stable isotope mixing models to estimate the contributions of different food types to cat diets. Additionally, we will plot the capture locations of each cat in a geographic information system (GIS) and character­ize the landscape surrounding each cat using data layers depicting the type and amount of land use and degree of urbanization. We predict that free-roaming cats living in more urbanized areas will consume primarily pet food and commensal vertebrates such as rats and mice, pigeons, and house sparrows, whereas those living in less urbanized areas and closer to natural open spaces will consume more wild and native prey species. Preliminary data analyzed to date suggest that many trapped cats rely on anthropogenic foods, including pet food, rather than consuming wild-caught prey, and that consumption of these food resources increases with the degree of urbanization around cat capture locations. We hope that our results can help inform management decisions about how and where to permit the implementation of TNR, especially in areas likely to support native species of conservation concern.

Roof rats (Rattus rattus) are a successful invasive species worldwide because of their ability to exploit their commensal relationship with humans. They are opportunistic feeders that use a wide range of natural and anthropogenic food sources. Because some rodent control methods, such as traps and rodenticides, threaten non-target wildlife species, understanding the diets of roof rats can help develop targeted approaches to better control these pests. Our aim is to use stable isotope analysis and stomach contents analysis to determine the diets of roof rats collected in agricultural, urban, and suburban areas in California. We hypothesized that diets of roof rats trapped in agricultural areas would contain crop plants and food resources associated with the agricultural environ­ment (arthropods, mollusks), whereas those from urban and suburban areas, e.g., schools, residential zones, would consume a broader range of food sources, including anthropogenic foods such as pet food, trash, and produce from gardens and fruit trees. To date, we have obtained roof rat carcasses from control efforts across the state, including our own trapping in southern California. Rats were frozen until they could be dissected in the lab. From each rat, we removed the gastrointestinal tract and took a small sample of ear tissue for stable isotope analysis; all tissues were stored in 95% ethanol. Ear tissue samples were dried, cut into small pieces, and weighed before sending them to the UC Davis Stable Isotope Facility for stable carbon (C) and nitrogen (N) isotope analysis. Stomachs were dissected under a dissecting microscope and food items were identified using reference keys. Preliminary analyses of stomach contents revealed significant amounts of what appears to be plant material, seeds, arthropod parts, and rodenticide bait, as well as many roundworms. Isotopic analysis of ear tissue of 64 rats from four Central Valley counties and urban/suburban rats from three southern California counties (n = 65) and Yolo County (n = 14) showed that δ13C values of rats from urban settings were significantly enriched compared to rural rats (Figure 1; F = 4.52, d.f. = 1, 141, P = 0.053), which is consistent with an urban diet containing more anthropogenic foods. δ13C values of urban roof rats were also much more variable (coefficient-of-variation, CV = 8.7%) than that of rats from agricultural areas (CV = 3.6%), which showed remarkably little variation within a site, indicative of feeding on a concentrated, shared resource. δ15N of rats differed significantly between agricultural counties (F = 195.9, d.f. = 3, 60, P

Rationale: The oxygen stable isotope ratio (δ18O) of the sugar‐rich fraction of fruit juice is important as a tracer of the geographical origin of raw material. This study sought to minimize the inter‐day variation of δ18O attributable to the influence of water to accurately monitor geographical origin labeling. Methods: Two drying devices (freeze dryer and vacuum oven) were compared. Then, two humidity levels (normal and low humidity) at which the samples were placed after drying were compared. The low‐humidity environment was constructed using a glove bag and pure argon gas. δ18O was measured using thermal conversion elemental analyzer/isotope ratio mass spectrometry. Improvements were made to the measurement method based on aforementioned analyses results, and the performance of the initial and improved methods was compared. Results: δ18O of juice dried in a vacuum oven was 3.30‰ lower than that of juice dried in a freeze dryer. Moreover, δ18O of juice samples exposed to normal humidity was 3.74‰ lower than that of samples exposed to low humidity. The combined inter‐day and intra‐day standard deviation was reduced from 1.20‰ in the initial method to 0.42‰ in the improved method. Conclusions: This study describes a pretreatment method for δ18O measurement in the sugar‐rich fraction of fruit juice with less inter‐day variation, and it will be useful for monitoring geographical origin labeling. [ABSTRACT FROM AUTHOR]

When evaluating the success of a stream restoration, it is pivotal to assess its ecological functionality as a sustainable habitat. In this study, we investigated fish communities across three sites with distinct structural features and environmental conditions in an urban restored stream located near the lower part of a major river. We analyzed the α‐ and β‐diversity of fish communities and estimated the restored stream's contribution to the river's fish diversity. We also examined ecological niche space and niche overlap among fish species using carbon and nitrogen stable isotope analysis. Results revealed that the restored stream increased overall diversity and β‐diversity in the region. Additionally, food web structure analysis showed variation in fish food source diversity among sites and species, resulting in diverse ecological niche areas and forms. The structural heterogeneity of the restored stream influenced fish feeding habits. However, many tolerant and invasive species were observed, with the invasive species Lepomis macrochirus markedly influencing competitive relationships with other fishes through its broad ecological niche area and overlap. These results emphasize the need to prioritize indigenous or non‐native species establishment during stream restoration. Overall, our study highlights the important role of restored streams in increasing catchment fish diversity. Nevertheless, food web‐centric monitoring and management strategies are necessary to effectively sustain local diversity. [ABSTRACT FROM AUTHOR]

The trophic organization of estuarine fish communities is poorly known. We used Stable Isotopes (δ13C and δ15N) to classify the most abundant fishes of the Atrato River Delta (Colombia) into trophic guilds. We examined trophic niches and the relationships between the abundance of the trophic guilds (catch per unit effort) and environmental variables. The zoobenthivores were the dominant trophic guild. The isotopic niche width, based on Bayesian estimate of the standard ellipse areas, was more significant for carnivores (25.3‰2) and planktivores (24.4‰2) than for omnivores (7.8‰2) and phytobenthivores (3.1‰2). The overlap combinations showed a medium probability of isotopic overlap (≈50%) between carnivores and planktivores and between carnivores and omnivores. Isotopic niche size and overlap suggested diversity in food sources and considerable niche segregation of the fish community. Mangrove area was the main factor explaining the abundance of omnivores and zoobenthivores, supporting that the causal links between mangrove habitat and local fishery production may be explained through the trophic contribution of mangroves and mangrove-related sources. The results underscore the importance of mangrove areas in the trophic organization of fish communities and can inform strategies aimed at managing the ecosystem impacts of fishing and protecting extensive mangrove areas in the southern Caribbean. [ABSTRACT FROM AUTHOR]

ABSTRACT Given the cryptic and elusive nature of prey consumption, quantifying its contribution to the diet of free‐ranging primates using behavioral methods is challenging. In this context, the use of carbon and nitrogen‐stable isotopes represents a promising alternative approach. Here, we used stable isotope analysis to estimate the proportion of arthropods and fruits in the diet of black lion tamarins (Leontopithecus chrysopygus), an endangered primate endemic to the Brazilian Atlantic Forest. To do so, we ran stable isotope mixing models using isotopic data from hair samples of black lion tamarins living in six forest fragments showing different levels of habitat quality. Furthermore, we ran linear mixed models to assess the influence of habitat quality—fruit productivity (estimated by tree total basal area) and arthropod biomass – and individual characteristics (sex and body mass) on tamarins' δ15N values (a proxy for trophic position). Our results revealed that arthropods contributed more to black lion tamarins' diet than reported in previous behavioral studies, suggesting that behavioral observations may considerably underestimate the importance of arthropodivory in the diet of arboreal primates. The degree of arthropodivory and frugivory was similar within groups, in line with the strong group cohesion and synchronization of feeding behaviors of this species and supporting the role of site‐specific habitat characteristics on dietary choice. Arthropod consumption was higher in areas with lower fruit productivity and did not increase when arthropod biomass increased, suggesting that fruits represent a limiting but preferred resource for this species. These results demonstrate the dietary plasticity of black lion tamarins in areas of lower forest quality, where they manage to compensate low fruit productivity by shifting to a diet richer in arthropods. Considering that this species occurs within a highly fragmented landscape, preserving and protecting small forest patches remains crucial for the conservation of this species. [ABSTRACT FROM AUTHOR]

Ecologists have long sought general explanations for the co‐occurrence of ecologically similar taxa. Niche theory explains co‐occurrence via functional differences among taxa that reduce competition and promote resource partitioning. Alternatively, the unified neutral theory of biodiversity and biogeography suggests that co‐occurrence can be attributed to stochastic processes, and thus, presupposes that ecologically similar species that occur in sympatry are functionally analogous. We test these hypotheses using the most diverse crustacean‐sea anemone symbiosis from coral reefs in the Tropical Western Atlantic. δ13C and δ15N stable isotope analyses of six crustacean symbionts that co‐occur around the host anemone Bartholomea annulata exhibit highly differentiated isotopic niche space spanning several trophic levels. As multiple crustacean species within the symbiosis have been documented as cleaners that remove parasites from reef fishes, we extended our investigation into the broader cleaner community. Our stable isotope analyses of cleaners shows that Pederson's cleaner shrimp Ancylomenes pedersoni exhibits the highest δ15N isotopic values‐ significantly higher than all other putative cleaner species and consistent with expectations of a dedicated cleaning lifestyle. However, for other species previously described or observed to clean reef fishes, including Periclimenes yucatanicus, Stenopus hispidus and Stenorhynchus seticornis, δ15N isotopic values were substantially lower, raising questions about the degree to which these species rely on cleaning interactions to meet their nutritional requirements. Taken together, our data are consistent with the expectations of niche theory: co‐occurring symbiotic crustaceans have highly partitioned niche space with low levels of functional redundancy. [ABSTRACT FROM AUTHOR]

A QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based multi-mycotoxin method was developed, analyzing 24 (17 free and 7 modified) Alternaria and Fusarium toxins in cereals via ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A modified QuEChERS approach was optimized for sample preparation. Quantification was conducted using a combination of stable isotope dilution analysis (SIDA) for nine toxins and matrix-matched calibration for ten toxins. Quantification via a structurally similar internal standard was conducted for four analytes. Alternariol-9-sulfate (AOH-9-S) was measured qualitatively. Limits of detection (LODs) were between 0.004 µg/kg for enniatin A1 (ENN A1) and 3.16 µg/kg for nivalenol (NIV), while the limits of quantification were between 0.013 and 11.8 µg/kg, respectively. The method was successfully applied to analyze 136 cereals and cereal-based foods, including 28 cereal-based infant food products. The analyzed samples were frequently contaminated with Alternaria toxins, proving their ubiquitous occurrence. Interestingly, in many of those samples, some modified Alternaria toxins occurred, mainly alternariol-3-sulfate (AOH-3-S) and alternariol monomethyl ether-3-sulfate (AME-3-S), thus highlighting the importance of including modified mycotoxins in the routine analysis as they may significantly add to the total exposure of their parent toxins. Over 95% of the analyzed samples were contaminated with at least one toxin. Despite the general contamination, no maximum or indicative levels were exceeded. [ABSTRACT FROM AUTHOR]

The plant kingdom exhibits a diversity of nutritional strategies, extending beyond complete autotrophy. In addition to full mycoheterotrophs and holoparasites, it is now recognized that a greater number of green plants than previously assumed use partly of fungal carbon. These are termed partial mycoheterotrophs or mixotrophs. Notably, some species exhibit a dependency on fungi exclusively during early ontogenetic stages, referred to as initial mycoheterotrophy. Japonolirion osense, a rare plant thriving in serpentinite soils, emerges as a potential candidate for initial mycoheterotrophy or mixotrophy. Several factors support this hypothesis, including its diminutive sizes of shoot and and seeds, the establishment of Paris-type arbuscular mycorrhizal associations, its placement within the Petrosaviales—largely composed of fully mycoheterotrophic species—and its ability to face the challenging conditions of its environment. To explore these possibilities, our study adopts a multidisciplinary approach, encompassing stable isotope abundance analyses, in vitro experiments, anatomical analyses, and comparative plastome analyses. Our study aims to (1) determine whether J. osense relies on fungal carbon during germination, indicating initial mycoheterotrophy, (2) determine if it employs a dual carbon acquisition strategy as an adult, and (3) investigate potential genomic reductions in photosynthetic capabilities. Contrary to expectations, our comprehensive findings strongly indicate that J. osense maintains complete autotrophy throughout its life cycle. This underscores the contrasting nutritional strategies evolved by species within the Petrosaviales. [ABSTRACT FROM AUTHOR]

In British Columbia, Canada, unidentified skeletal human remains are often recovered by law enforcement or civilians and there is a question if they are modern and of medicolegal significance, or historical or archaeological. We used relatively fast and inexpensive carbon and nitrogen stable isotope analysis of human bone collagen from a selection of these remains (n = 48) combined with a logistic regression model to classify remains as modern, historical, or archaeological. We then confirmed our temporal classification through directly radiocarbon dating each individual and found that we could predict the temporal group with 93% accuracy. In regions where archaeological remains have dietary isotope values distinct from living people, dietary stable isotope analysis can provide a time‐, and resource‐efficient method to screen cases of unidentified human remains early in death investigation. [ABSTRACT FROM AUTHOR]

In this study, using a dendrological and isotopic approaches, we investigated the responses to climate of two pure Fagus sylvatica L. stands (Campobraca and Falode) in the southernmost part of the distribution range in southern Italy. The δ13C data were used for calculating the intrinsic water use efficiency (iWUE) as a proxy of the balance between the water and carbon cycles. The results showed that the iWUE of both stands was sensitive to the amount of precipitation during the summer months (negative, significant effect) and to atmospheric CO2 concentration. Growth was sensitive to climate only in the Campo Braca site; the most influential variables were the VPD (vapour pressure deficit) and precipitation of the summer months that had a negative and a positive effect, respectively. The iWUE showed a negative correlation with growth in Campo Braca and a non-significant one in Falode. Water availability was the most influential variable on F. sylvatica growth and physiology. The iWUE increase was mainly driven by atmospheric CO2 concentration, and by decreased precipitation, as a response of the trees to drought. Our results highlight the importance of understanding the hydrological changes due to climate change for forecasting/modelling forest responses. CO2 increase does not compensate for the effect of adverse climate on F. sylvatica in the forests of southern Italy, while local conditions play an important role in determining tree growth. [ABSTRACT FROM AUTHOR]

Although rhizoctonias from Ceratobasidiaceae, Tulasnellaceae and Serendipitaceae are typical orchid mycobionts, orchid mycorrhizal fungi exhibit vast taxonomic and ecological diversity. This diversity stems from the high specificity of orchid mycorrhizal associations and the remarkable diversity of over 28,000 orchid species. The subtribe Calypsoinae is particularly notable for its diverse mycorrhizal partnerships, including rhizoctonias, ectomycorrhizal and saprotrophic non‐rhizoctonia fungi. However, the mycobionts within certain Calypsoinae lineages, such as the genus Dactylostalix, remain understudied. This study explores the physiological ecology of two photosynthetic Calypsoinae species, Dactylostalix ringens and Dactylostalix uniflora, to gain insight into potentially novel associations and their ecological implications. We analysed the mycorrhizal communities of both Dactylostalix species using high‐throughput ITS metabarcoding of root samples collected from multiple locations. Additionally, we measured the natural abundances of 13C and 15N isotopes in the leaves of the two Dactylostalix species and their co‐occurring autotrophic reference plants, as well as in fungal pelotons isolated from D. ringens, to assess the potential for partial mycoheterotrophy. Our findings revealed that D. ringens and D. uniflora form specialized mycorrhizal associations predominantly with distinct lineages of Oliveonia (Oliveoniaceae, Auriculariales), even in sympatric populations. Stable isotope analysis showed that both Dactylostalix species exhibited conflicting isotopic signals: elevated δ15N values, supporting partial mycoheterotrophy, but lower δ13C values compared to autotrophic plants, suggesting autotrophy. Peloton samples from D. ringens displayed only modest 13C enrichment relative to autotrophic references. These conflicting isotopic signals make it difficult to precisely determine whether both Dactylostalix species are autotrophic or partially mycoheterotrophic. Intriguingly, the 13C and 15N signatures of Dactylostalix species and their pelotons resemble those of many rhizoctonia‐associated orchids. This isotopic evidence implies a niche overlap with endophytic tendencies between rhizoctonias and Oliveonia, suggesting that potential endophytic traits may have facilitated the recruitment of Oliveonia as novel mycorrhizal partners. Furthermore, the mycorrhizal segregation between D. ringens and D. uniflora likely promotes their sympatric coexistence and may contribute to reproductive isolation through ecological specialization. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Understanding an organism's niche and ecological role in its ecosystem is critical for conservation, especially for species that use multiple habitats at different life stages. The hawksbill sea turtle (Eretmochelys imbricata) is one such migratory animal that plays an ecologically important role in imperiled coral reef habitats. Hawksbill resource use strategies (e.g., generalism vs. specialism) in these foraging grounds are poorly understood, yet stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) can provide information on the trophic niche and foraging location of consumers. Additionally, when a single sample is taken from a tissue that accretes through time, such as keratin, analyses can reveal information on the long-term foraging patterns of individuals. Here, we evaluate resource use strategies for 98 females within a nesting aggregation of hawksbills on the island of Antigua (17.159, -61.756) in the Eastern Caribbean. Stable isotope analysis of scute tissue collected from 2017 to 2019 revealed population-level generalism and varying degrees of individual specialization. Additionally, reproductive age was significantly related to niche width, with younger turtles showing higher variability in their isotopic record. Older turtles displayed overall smaller ranges in isotope values, indicating a narrowing of resource use with increased reproductive age amongst breeding adult females. These findings provide evidence of high variability in hawksbill diet, illustrate differences in ecological niche use across different ages, and highlight the necessity of evaluating multiple life stages to inform the conservation of this critically endangered species. [ABSTRACT FROM AUTHOR]

Early juvenile loggerhead turtles (Caretta caretta) rely on gelatinous zooplankton, whereas individuals larger than 40 cm curved carapace length are adapted to crush hard-shelled invertebrates. Nevertheless, fish were reported to be the staple food of loggerhead turtles in the western Mediterranean 30 years ago. Here, the temporal consistency of such a fish-based diet of loggerhead turtles is assessed through gut content analysis and stable isotope analysis of samples from the Mediterranean coast of Spain spanning three decades. The gut contents of 134 juvenile loggerhead turtles (curved carapace length range: 27–71 cm) from three different periods (1991, 1999–2008 and 2010–2017) were analyzed, as well as a subsample of the same turtles (n = 10 in each period) for both bulk and compound-specific stable isotope ratios (CSIA-AA). Gut content analysis revealed a decline in the frequency of occurrence and numerical abundance of fish and an increasing contribution of gastropods and bivalves throughout time, although pelagic tunicates were always the most frequently observed prey. The δ15Nbulk of turtle bone also dropped throughout the study period, but the values of the stable isotope ratio of N in phenylalanine (δ15NPhe) indicated that 52.5% of that variability was due to a baseline shift over time. Accordingly, the trophic position estimated from CSIA-AA did not follow the decreasing pattern of δ15Nbulk, but fluctuated throughout time. The overall evidence indicates that fish consumption by loggerhead turtles in the study region declined through time, but the trophic position of loggerhead turtles did not change simultaneously. This is probably because low trophic prey such pelagic tunicates and filter-feeding bivalves and suspension-feeding gastropods were the bulk of the diet during the whole study period and fish played a minor role, even when their frequency of occurrence peaked. Past levels of high fish consumption might be due to high levels of fishery discards, currently declining because of the recent reduction of the fishing fleet. [ABSTRACT FROM AUTHOR]

Stable isotope analysis of fish muscle tissue has been used to quantify fish migratory behavior in many systems, and these chemical tracers are especially useful for euryhaline fishes that traverse significant salinities and gradients in baseline signatures. However, the removal of muscle tissues often requires lethal sampling. Fish scales may be removed non‐lethally and offer potential alternatives to stable isotope ratios from muscle to indicate recent feeding histories. For this study, red drum Sciaenops ocellatus were collected in subtropical estuaries in the northwestern Gulf of Mexico and analyzed for stable isotope (훿13C and 훿15N) compositions of scale exteriors. Decalcification of scale samples was deemed unnecessary given the preservation of linearity and minimal offsets between paired decalcified and untreated scale samples. Stable isotope signatures of muscle tissue and scales were closely matched and indicated high degrees of residence within bays at fine spatial scales. This study also surveyed the existing body of literature comparing scale and muscle isotope values from the same individuals and found that the majority reports linear relationships with slopes close to unity, although species‐specific offsets and intercepts vary. This work expands the body of literature indicating that scales are a viable non‐lethal alternative for stable isotope assessments of dietary and habitat use histories for mobile fishes. [ABSTRACT FROM AUTHOR]

Patterns of mother–embryo fractionation of 13C and 15N were assessed for their predictability across three species of batoids caught as by‐catch in south‐eastern Australia. Stable isotope analysis of 24 mothers and their litters revealed that isotope ratios of embryos were significantly different from their corresponding mothers and that the scale and direction of the difference varied within and across species. The range of variation across species was 3.5‰ for δ13C and 4‰ for δ15N, equivalent to a difference in trophic level. In one species (Urolophus paucimaculatus) litters could be significantly enriched or depleted in 13C and 15N relative to their mothers' isotope signatures. These results suggest that patterns of mother–embryo isotope fractionation vary within and between species and that these patterns may not be explained only by developmental mode. Contrasting patterns of fractionation between and within species make it difficult to adjust mother–embryo fractionation with broad‐scale correction factors. [ABSTRACT FROM AUTHOR]

Seasonal differences in the availability of resources potentially result in the food web architecture also varying through time. Stable isotope analyses are a logistically simple but powerful tool for inferring trophic interactions and food web structure, but relatively few studies quantify seasonal variations in the food web structure or nutrient flux across multiple trophic levels. We determined the temporal dynamics in stable isotope compositions (carbon, nitrogen and sulphur) of a fish community from a highly seasonal, temperate estuary sampled monthly over a full annual cycle. Sulphur isotope values in fish tissues discriminated among consumers exploiting pelagic and benthic resources but showed no seasonal variation. This implied limited change in the relative consumption of pelagic and benthic resources by the fish community over the study period despite major seasonal changes in phytoplankton biomass. Conversely, carbon and nitrogen isotope values exhibited seasonality marked by the commencement of the spring phytoplankton bloom and peak chlorophyll concentration, with δ13C values following expected trends in phytoplankton growth physiology and variation in δ15N values coinciding with changes in major nitrogen sources to plankton between nitrate and ammonium. Isotope shifts in fish muscle were detected within 2 weeks of the peak spring phytoplankton bloom, suggesting a rapid trophic transfer of carbon and nitrogen along food chains within the estuarine food web during periods of high production. Therefore we caution against the assumption that temporal averaging effectively dampens isotopic variability in tissues of higher trophic‐level animals in highly dynamic ecosystems, such as temperate estuaries. This work highlights how stable isotope analyses can be combined with environmental data to gain a broader understanding of ecosystem functioning, while emphasising the need for temporally appropriate sampling in stable isotope‐based studies. [ABSTRACT FROM AUTHOR]

Migrations between spawning, growth and refuge habitats are critical for many fish species. Partially migratory populations of brook charr Salvelinus fontinalis (known as brook trout in the United States), in which a portion of the population migrates, were once widespread in the Great Lakes region of North America, but are now scarce and a rehabilitation priority. Great Lakes fishery managers lack a simple, non-lethal means to determine whether a large brook charr caught in a Great Lakes accessible stream reach represents a stream-resident fish or migrant that previously spent time foraging and growing in Great Lakes waters. We explored a relatively inexpensive and non-lethal stable isotope approach for documenting lake to stream movements of brook charr, using fin clips from brook charr captured in streams in fall prior to spawning. Using fin tissue from juvenile and adult coho salmon captured in Michigan tributaries to Lake Superior, we confirmed distinct stable isotope signatures indicative of prior stream and Lake Superior foraging. We identified brook charr from tributaries accessible to Lake Superior whose stable isotope signatures were similar to those of lake-captured brook charr, lake charr and splake (a brook charr–lake charr hybrid) and distinct from stable isotope signatures of brook charr in streams inaccessible to Lake Superior fishes, suggestive of an adfluvial migratory pattern. Brook charr from two streams had elevated δ15N values, indicative of previous residency in a downstream lake receiving water from a sewage treatment facility. Our findings demonstrate the utility of stable isotope analysis as a non-lethal technique for confirming adfluvial movements of brook charr from Lake Superior to streams. [ABSTRACT FROM AUTHOR]

Understanding past fire regimes requires reliable proxy data that record fire conditions and preserve them over time. The objective of this study was to determine if the oxygen isotope composition of charred bark samples (pyrogenic organic matter) could be used as proxy data to differentiate wildfires based on burn intensity. We collected charred and uncharred bark samples from three fire sites in northern Ontario, Canada that represented a gradient of fire intensity as depicted by Fire Weather Index (FWI) data. We hypothesized that the mean Δ18Obark-char (the difference between δ18O of uncharred bark and a charred sample) would be greater for fires with higher intensities. Analysis of variance of Δ18Obark-char indicated a significant effect of fire event (F = 73.6, p < 0.001), which explained 57.0% of the variance. A prescribed surface fire treatment (mean FWI = 9.5) had significantly lower Δ18Obark-char than two natural crown fires (FWI = 21 and 27). These results demonstrate that Δ18Obark-char differentiated moderate from high intensity fires in a similar manner to the FWI data. [ABSTRACT FROM AUTHOR]

The stable isotope analysis of black powder (BP) is of great significance for its comparison and source inference. Previous studies have verified the feasibility of distinguishing different BP samples through stable isotopes. However, the impact of raw materials and synthesis processes on the stable isotopes of BP remains unclear. On the one hand, the raw materials of BP are widely sourced, and whether stable isotopes can distinguish different source materials remains to be studied. On the other hand, the synthesis of BP involves the physical mixing of raw materials, and whether this process leads to isotope fractionation also needs further investigation. To address these problems, stable isotope ratios of 27 charcoals, 15 potassium nitrates, 6 self‐made and 10 commercial BP samples were analyzed. The results showed that the stable isotope ratios can be utilized to distinguish charcoals and potassium nitrates from different manufacturers and batches. No significant differences in the nitrogen and oxygen stable isotope ratios between the self‐made BP and its raw materials were observed, indicating that the physical mixing process does not induce significant fractionation of stable isotopes. However, the carbon stable isotope ratios of charcoal increased (within 2SD) after being synthesized into BP. Due to the utilization of additives and variations in the synthesis process, the correlation between the stable isotope ratios of commercial BP and its raw materials was complex. The findings of this study provide a scientific reference for tracing the source of BP. [ABSTRACT FROM AUTHOR]

Chlorophyllous plants exhibiting partial mycoheterotrophy obtain carbon through mycorrhizal interactions in addition to photosynthesis. In arbuscular mycorrhizal (AM) plants, the Paris‐morphotype (i.e. hyphal coils) is considered essential for mycoheterotrophic carbon gains. Numerous tree species in tropical lowland forests form this morphotype, and under light‐ and nutrient‐limitation, additional carbon gain would be beneficial. However, if seedlings of woody species in the understory of tropical lowland forests exhibit partial mycoheterotrophy remains unexplored. Here we (a) examined the AM morphotype (Paris‐ or Arum‐type) in seedlings of 41 tropical woody species, and (b) to determine if any of the target Paris‐type species are partially mycoheterotrophic, we compared their multi‐element stable isotope natural abundance (13C, 2H, 18O, 15N) with neighbouring autotrophic non‐Paris‐type reference seedlings. About 50% of the investigated species (and 80% of the genera) exhibited the Paris‐type, expanding the number of tropical plant genera with Paris‐type AM. Enrichment in 13C, but not in 18O in target compared with neighbouring reference plants indicated partial mycoheterotrophy in seedlings of 6 of the 21 investigated Paris‐type AM species. Our results indicate for the first time that carbon gain through mycoheterotrophy occurs in seedlings of AM tropical tree species. In tropical forests, partial mycoheterotrophy during seedling establishment may confer so far unrecognised ecological advantages influencing seedling recruitment and ecosystem dynamics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an essential element for sustaining human life, but its current management is unsustainable. Scientists are currently developing novel scientific and technological innovations to improve P management. By engaging stakeholders to understand their perceptions and concerns, researchers can address concerns and improve the chances that their innovations will be adopted. In this paper, we conducted thirty-seven interviews with U.S. stakeholders to develop three case studies of technologies in P recovery. The cases investigated are i) urine diversion for P recovery, ii) biological P removal from wastewater, and iii) analysis of stable isotopes for source tracking in natural water bodies. Stakeholders highlighted an array of economic, regulatory, and social barriers to adoption that were similar across all three cases. The findings presented in this study provide proof of concept for the efficacy of comparative methods to identify shared challenges in adoptions of new innovations within a research area. [ABSTRACT FROM AUTHOR]

Nitrogen stable isotope ratios (δ15N) are widely used to quantify trophic position in aquatic ecosystems. Comparing trophic position across space requires identifying baselines to account for variation in δ15N values of basal energy resources, but few standardized methods exist for identifying suitable baselines. We evaluated a standardized method for identifying optimal isotopic baselines in streams spanning the Rocky Mountains–Great Plains ecotone. We assessed candidate taxonomic groups and feeding groups following four criteria: (1) Organisms should be easy to collect and widely distributed, (2) Within-site δ15N variation should be low (representative of uniform feeding behavior), (3) δ15N values should be correlated with geographic variability in δ15N values, and (4) Trophic position of consumers calculated using the baseline should be independent of geographic δ15N variability when there is no change in diet. Simuliidae (obligate, sestonic filter feeders) met all four criteria for four fishes and produced trophic position estimates consistent with dietary changes for brown trout along a longitudinal stream gradient. The four-criteria screening method is suitable for temperate streams in North America and supports the recommendation to use Simuliidae or potentially grouped filter feeders as baseline organisms for stable isotope studies quantifying trophic position in higher-order consumers. [ABSTRACT FROM AUTHOR]

The Jingbai pear is one of the best pear species in China with high quality and nutrition values which are closely linked to its geographical origin. With the purpose of discriminating the PGI Mentougou Jingbai pear from three other producing regions, the stable isotope ratios and elemental profiles of the pears (n = 52) and the corresponding soils and groundwater were determined using isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results revealed that δ15N, δ18OJ, and Li were significantly different (p < 0.05) in samples from different regions, which indicated their potential to be used in the geographical origin classification of the Jingbai pear. The nitrogen isotopic values of the pear pulp were positively correlated with the δ15N value and nitrogen content of the corresponding soils, whilst the B, Na, K, Cr, and Cd contents of the pear pulps were positively correlated with their corresponding soils. Orthogonal partial least squares discriminant analysis (OPLS-DA) was performed in combination with analysis of the stable isotopes and elemental profiles, making it possible to distinguish the cultivation regions from each other with a high prediction accuracy (a correct classification rate of 92.3%). The results of this study highlight the potential of stable isotope ratios and elemental profiles to trace the geographical origin of pears at a small spatial scale. [ABSTRACT FROM AUTHOR]

High-value products, such as hazelnuts, are particularly vulnerable to fraud due to their price dependence on geographical origin. Guaranteeing hazelnuts' authenticity is essential for consumer trust and safety. Stable isotope analysis has become a reference method for origin authentication as it is reliable, robust, and easily transferable across laboratories. However, multiple isotopic markers coupled with chemometric techniques are often needed to authenticate food provenance accurately. In this study, we focused on assessing the potential of bulk δ18O, along with δ2H and δ13C of the main fatty acids, as hazelnut-origin authenticity markers. PLS-DA classification models were developed to differentiate samples (n = 207) according to their region of origin. This multi-isotopic approach provided promising external validation results, achieving a 94% global correct classification rate in discriminating hazelnuts from regions with distinct geographical and environmental conditions. This study lays the groundwork for further model development and evaluation across additional production areas and harvest years. [ABSTRACT FROM AUTHOR]

Globalization and free market dynamics have significantly impacted state economies, particularly in the wine industry. These forces have introduced greater diversity in wine products but have also heightened the risk of food fraud, especially in high-value commodities like wine. Due to its market value and the premium placed on quality, wine is frequently subject to adulteration. This issue is often addressed through regulatory trademarks on wine labels, such as Protected Designation of Origin (PDO) and Protected Geographic Indication (PGI). In this context, the metabolic profiles (organic acids, carbohydrates, and phenols) and stable isotope signatures (δ13C, δ18O, D/HI, and D/HII) of red and white wines from four agroclimatically similar regions were examined. The study explored how factors such as grape variety, harvest year, and geographical origin affect wine composition, with a particular focus on distinguishing samples from cross-border areas. Multivariate statistical analysis was used to assess the variability in wine composition and to identify distinct groups of samples. Preliminary results revealed that organic acids and volatile compounds were found in lower concentrations than carbohydrates but were significantly higher than phenols, with levels ranging between 1617 mg/L and 6258 mg/L. Carbohydrate content in the wines varied from 8285 mg/L to 14662 mg/L. Principal Component Analysis (PCA) indicated certain separation trends based on the variance in carbohydrates (e.g., fructose, glucose, galactose) and isotopic composition. However, Discriminant Analysis (DA) provided clear distinctions based on harvest year, variety, and geographical origin. [ABSTRACT FROM AUTHOR]

Temporal variation in resource availability, amplified by global change, may have strong impacts on species breeding at temperate and high latitudes that cue their reproduction to exploit seasonal resource pulses. This study examines how resource availability and parental care influence niche partitioning between and within age classes in the rufous‐collared sparrow, which provides extensive parental care. We hypothesized juveniles would exhibit narrower niches focused on high‐quality resources compared to adults, regardless of resource availability. We used stable isotope analysis to quantify individual and population niches in juveniles and adults across the breeding season in two cohorts experiencing contrasting resource landscapes. Contrary to our initial hypothesis, juveniles exhibited greater among‐individual diet variation and smaller total niche widths (i.e. higher levels of individual specialization, IS) during periods of high food availability in comparison to periods of food scarcity. Interestingly, total niche width and IS of adults remained stable across seasons despite a shift in trophic level, highlighting their potential role in providing a consistent diet for their young. These findings reveal a dynamic interplay between resource availability, parental care, and IS, with important implications for understanding population resilience under variable resource scenarios. The study also suggests that adult sparrows modify their provisioning strategies based on resources, potentially buffering offspring from environmental fluctuations. Understanding age‐specific responses to resource variation is crucial for predicting species responses to ecological conditions, particularly in regions like central Chile where seasonal resource limitation is expected to become more variable in response to climate change. [ABSTRACT FROM AUTHOR]

Understanding the stable hydrogen isotope (δ2H) composition and fractionation in lipid biomolecules of primary producers, such as terrestrial and aquatic plants, is crucial for deciphering past environmental conditions, as well as applying compound-specific stable isotope analysis for the study of metabolic and ecological processes. We conducted a new tracer experiment to explore the δ2H composition of algal fatty acid biomarkers, focusing on freshwater algae, which form the base of aquatic food webs. We selected a range of algal species widely found in freshwater ecosystems and cultivated them under controlled conditions. First, we added 2H2O to ambient water as a tracer to investigate the net hydrogen isotope fractionation during algal lipid synthesis at isotopic equilibrium, which is particularly informative for paleo-geochemical studies. Then, we conducted kinetic experiments to quantify the time needed for algal fatty acids to achieve isotopic steady-state conditions in response to the change in ambient water δ2H values. Our findings revealed substantial variability in hydrogen isotope fractionation among different algal taxa and various fatty acids. Based on taxa, different fatty acids exhibited faster integration of water hydrogen than others, but they were not necessarily in the order of the biosynthetic pathway. This experiment underscores the complexity of hydrogen isotope fractionation and the requirement for controlled laboratory studies to properly apply compound-specific stable H isotope analysis techniques in ecological and paleo-environmental studies. [ABSTRACT FROM AUTHOR]

The Xiaheqiadong site located in Zhangqiu district, Jinan city, Shandong province, China, was excavated in 2016 by the Jinan Institute of Archaeology, which revealed six single burials dating to the Beixin culture period (ca. 5,300–4,500 BC to ca. 4,100–3,600 BC). This paper used bioarchaeological methods to study the human skeletal remains to reconstruct the life course of the residents of the Beixin culture at the Xiaheqiadong site, focusing on stable isotope analysis, evaluation of stress, tooth ablation, and intentional skull modification. Based on stable isotope analysis of carbon, it is evident that the dietary structure of the ancient residents of Xiaheqiadong was mainly dependent on C4 plants or animals that ate mainly C4 plants. The stable isotope analysis of nitrogen indicated that the ancient residents of the Xiaheqiadong site exhibited a relatively sufficient consumption of animal protein. Furthermore, this result also reveals that a subsistence economic model was established consisting of farming, gathering, and hunting. Observations of the stress indicators (including cribra orbitalia, porotic hyperostosis, and linear enamel hypoplasia) revealed that they experienced poor health conditions and were under high levels of stress during infancy and early childhood. However, this situation improved with increasing age, suggesting that residents from the Xiaheqiadong site had the capacity to withstand severe living conditions and adapt after experiencing stress events. The tooth ablation and occipital modification cases from the Xiaheqiadong site are the earliest cases among the individuals with accurate dating results found in China. [ABSTRACT FROM AUTHOR]

The article discusses the design and performance assessment of a low-cost rain collector for stable isotope samples, focusing on the importance of oxygen and hydrogen isotope ratios in precipitation for hydroclimatic studies. The study presents a low-cost rain collector design that minimizes post-collection fractionation, validated through control experiments in Delhi during the 2023 summer monsoon. The rain collector's cost-effective construction and performance make it suitable for establishing dense sampling networks for rainfall isotopes, providing valuable insights into past and present hydroclimate dynamics. The study highlights the significance of appropriate rainwater collection methods to preserve sample integrity and isotopic composition for research purposes. [Extracted from the article]

American black bear (Ursus americanus) populations are increasing throughout much of North America. Use of multiple harvest methods, including hunting over bait, is intended to increase harvest success rates to meet harvest and population management objectives. However, black bear population growth can be influenced by food availability, and some speculate the use of bait may inadvertently increase bear abundance through food resource supplementation. We collected hair from black bears captured from 2005–2019 and a selection of potential food items, including those used as bait from 3 study areas in Maine, USA, with different levels of human influence. We used stable isotope analysis of the black bear hair and food item samples to evaluate the contribution of different identified food groups to the diet of individual bears. We found no evidence that greater contribution of human food resources, including bait, increased the number of cubs per litter for reproductive females or that human foods comprised a greater part of the diet in years when natural food resources were less abundant. Approximately 69% of black bear harvest occurred over bait. We found the probability of reproductive‐age females to be harvested increased with average representation of human foods with high carbon enrichment (including bait) in their diet, but the relationship was weak, likely because of sampling constraints. Additionally, the probability of being harvested was greater in years when natural food resources were scarce. We conclude that bait is not available on the landscape in large enough amounts or for a sufficient amount of time in Maine to substantially influence female reproduction. Our results indicate hunting over bait is an effective tool in a state that is attempting to maintain a stable bear population via harvest, and dispels conjecture that hunting over bait may increase cub production and offset the intention of harvest. [ABSTRACT FROM AUTHOR]

AbstractAroma is one of the important indexes to evaluate food quality. The formation of food aroma is based on the interaction of complex substances. The accurate quantification of aroma substances in food has significance in the analysis of aroma substances in food. In this review, the basic principle and significance of stable isotope dilution analysis is introduced, general steps for flavor analysis and its historical progress in food flavor analysis is discussed. Additionally, the application progress of stable isotope dilution analysis in food flavor analysis from 2019 to 2023 has been described in detail, which is also categorized by food. Finally, the accuracy and superiority of stable isotope dilution analysis as an accurate quantitative analysis method were discussed. [ABSTRACT FROM AUTHOR]

Aims Materials and Methods Results Conclusions Roux‐en‐Y gastric bypass (RYGB) surgery alters postprandial glucose profiles, causing post‐bariatric hypoglycaemia (PBH) in some individuals. Due to the liver's central role in glucose homeostasis, hepatic glucose handling might differ in RYGB‐operated patients with PBH compared to non‐operated healthy controls (HC).We enrolled RYGB‐operated adults with PBH and HCs (n = 10 each). Participants ingested 60 g of [6,6′‐2H2]‐glucose (d‐glucose) after an overnight fast. Deuterium metabolic imaging (DMI) with interleaved 13C magnetic resonance spectroscopy was performed before and until 150 min post‐d‐glucose intake, with frequent blood sampling to quantify glucose enrichment and gluco‐regulatory hormones until 180 min. Glucose fluxes were assessed by mathematical modelling. Outcome trajectories were described using generalized additive models.In RYGB subjects, the hepatic d‐glucose signal increased early, followed by a decrease, whereas HCs exhibited a gradual increase and consecutive stabilization. Postprandial hepatic glycogen accumulation and the suppression of endogenous glucose production were lower in RYGB patients than in HCs, despite higher insulin exposure, indicating lower hepatic insulin sensitivity. The systemic rate of ingested d‐glucose was faster in RYGB, leading to a higher, earlier plasma glucose peak and increased insulin secretion. Postprandial glucose disposal increased in RYGB patients, without between‐group differences in peripheral insulin sensitivity.Exploiting DMI with stable isotope flux analysis, we observed distinct postprandial hepatic glucose trajectories and parameters of glucose–insulin homeostasis in RYGB patients with PBH versus HCs. Despite altered postprandial glucose kinetics and higher insulin exposure, there was no evidence of impaired hepatic glucose uptake or output predisposing to PBH in RYGB patients. [ABSTRACT FROM AUTHOR]

Unraveling factors that enable the coexistence of species occupying similar niches is a challenge in Ecology. In the Amazon basin, several piranha species (Serrasalmidae) co-occur in floodplain lakes, providing a model to understand how similar species manage coexisting. We employed a combination of classic and molecular stomach contents analysis, and stable isotope analysis to evaluate the use of resources and isotopic niche breadth among three co-occurring piranha species (Serrasalmus altispinis, S. maculatus, and Pygocentrus nattereri), and the influence of the hydrological cycle (low vs. high water) in resources partitioning. A higher diversity of prey and lower isotopic niches was found during low water, likely due to prey concentration. Cannibalism occurred in all three species, and although piscivores, these species feed on different trophic levels, with P. nattereri consuming omnivores, S. maculatus detritivores, and S. altispinis herbivores. Coexistence was mediated by changes in resource availability associated with the hydrologic cycle. Trophic niche overlap was higher during the high water compared to low waters due to high prey availability when lakes connect to river channels and floodplain forests. Here, we identified strategies used by piranhas to avoid competition under different environmental conditions. Understanding species interactions is fundamental to managing biodiversity conservation in a changing world. [ABSTRACT FROM AUTHOR]

Rationale: Stable isotope analysis of bone provides insight into animal foraging and allows for ecological reconstructions over time, however pre‐treatment is required to isolate collagen. Pre‐treatments typically consist of demineralization to remove inorganic components and/or lipid extraction to remove fats, but these protocols can differentially affect stable carbon (δ13C) and nitrogen (δ15N) isotope values depending on the chemicals, tissues, and/or species involved. Species‐specific methodologies create a standard for comparability across studies and enhance understanding of collagen isolation from modern cetacean bone. Methods: Elemental analyzers coupled to isotope ratio mass spectrometers were used to measure the δ13C and δ15N values of powdered killer whale (Orcinus orca) bone that was intact (control) or subjected to one of three experimental conditions: demineralized, lipid‐extracted, and both demineralized and lipid‐extracted. Additionally, C:N ratios were evaluated as a proxy for collagen purity. Lastly, correlations were examined between control C:N ratios vs. historical age and control C:N ratios vs. sample characteristics. Results: No significant differences in the δ15N values were observed for any of the experimental protocols. However, the δ13C values were significantly increased by all three experimental protocols: demineralization, lipid extraction, and both treatments combined. The most influential protocol was both demineralization and lipid extraction. Measures of the C:N ratios were also significantly lowered by demineralization and both treatments combined, indicating the material was closer to pure collagen after the treatments. Collagen purity as indicated via C:N ratio was not correlated with historical age nor sample characteristics. Conclusions: If only the δ15N values from killer whale bone are of interest for analysis, no pre‐treatment seems necessary. If the δ13C values are of interest, samples should be both demineralized and lipid‐extracted. As historical age and specimen characteristics are not correlated with sample contamination, all samples can be treated equally. [ABSTRACT FROM AUTHOR]

ABSTRACT 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]

Magnesite is an economically important mineral commonly found in ultramafic complexes worldwide, primarily in Archean to Proterozoic ultramafic complexes. This study focuses on the chemical and spectral characterization of magnesite found in the Neoarchean ultramafic rocks in the Attappadi region in the Southern Granulite Terrane of southern India. The research utilizes x‐ray diffraction analysis, hyperspectral, laser Raman, Fourier Transform Infrared, and Isotope Ratio Mass Spectrometry. The studied ultramafic rocks are part of a well‐exposed ophiolitic suite known as the Agali ophiolitic complex. Magnesite primarily occurs as veins, veinlets, and lenses within weathered ultramafic rocks. The hyperspectral analysis of the magnesite samples shows absorption bands in the shortwave infrared region, particularly around 2.3 and 2.5 μm, which correspond to the stretching and bending of the CO bond in the (CO3)2− ion in MgCO3. The laser Raman spectra show intensity peaks at 1095, 738, and 330 cm−1, which may be attributed to the translational and librational vibrations. The Fourier transform infrared data reveal transmittance at 1434, 880, and 747 cm−1, corresponding to MgO bond stretching and asymmetrical CO stretching. The x‐ray powder diffraction spectra exhibit diffraction peaks at 32°, 35°, 42°, 46° and 53°, characteristic of pure magnesite. The spectroscopic parameters derived from various analyses indicate that the magnesite is high quality and free from gangue minerals. Stable isotope analysis of the magnesite samples yielded δ13C values ranging from −5‰ to −9‰ and δ18O values in the range of 21‰–25‰. The estimated water temperature from which the magnesite has been precipitated is ~59 ± 3.9°C. Based on the field relations, mode of occurrence and isotopic signatures, the mineralization is considered to have been formed by the low‐temperature alteration of ultramafic rocks facilitated by CO2‐rich fluids in the near‐surface environment. This study compares the characteristics of magnesite from the study area with a few Neoproterozoic serpentinite‐hosted magnesite veins in the ophiolitic sequence of the Egyptian Eastern Desert, which is part of the Arabian Nubian shield. The research aims to contribute to understanding magnesite formation in Archaean to Proterozoic mafic–ultramafic rocks on the Earth's crust. It also provides insights into the geological processes that govern the genesis of ultramafic‐hosted magnesite globally, particularly in East Gondwana fragments. This information can enhance mineral exploration and resource evaluation in these regions, helping to identify economic prospects and assess the feasibility of magnesite resource extraction and utilization in East Gondwana fragments. [ABSTRACT FROM AUTHOR]

Microbialite reservoirs are of great importance in oil and gas exploration. However, there is still a lack of comprehensive studies on the formation mechanisms of thrombolitic reservoirs, a specific type of microbialite. This research focuses on the oldest thrombolitic dolomite reservoir located within the Precambrian Dengying Formation in the central Sichuan Basin, southwestern China. A multi-disciplinary approach was employed to characterize different thrombolite facies and elucidate the formation mechanism of thrombolitic dolomite reservoirs and their controlling factors, involving core observation, thin-section analysis, cathodoluminescence, scanning electron microscope (SEM) microscopy, elemental analysis using LA-ICP-MS, and carbon and oxygen stable isotope analysis. Based on variations in texture, four types of thrombolite were identified: 1) distinct clotted thrombolite, 2) diffuse and regular clotted thrombolite, 3) diffuse and irregular clotted thrombolite, and 4) composite clotted thrombolite. Notably, the diffuse clotted thrombolitic dolomite is the prevalent lithology in the reservoir. Through modification by meteoric water, organic acid fluids, and hydrothermal fluids, a reservoir with dominant porosity in the form of primary growth-framework pores, dissolution pores, and vugs was formed. This resulted in the development of two high-quality reservoir intervals within the Second Member and at the top of the Fourth Member of the Dengying Formation. The growth-framework porosity of the thrombolites, epigenetic karstification, and tectonic fracturing were mainly conducive to reservoir development. However, various types of cementation have reduced porosity and connectivity within the reservoir. Overall, this study is a valuable example of the methodology required to understand meso- and microstructures of deep-buried thrombotic dolomite reservoirs, including their heterogeneities and diagenesis, as the original structures influence diagenesis. [ABSTRACT FROM AUTHOR]

Explicit identification of hydrochemical processes and their controlling factors within groundwater systems is critical for the sustainable utilization of water resources in coastal urban areas. This study was undertaken in the North Coastal Region of Jiaozhou Bay (NCRJB), located in the eastern part of Shandong Province, China, an area grappling with significant issues of groundwater quality degradation and water scarcity. A total of 105 groundwater samples and 34 surface water samples, collected from 2020 to 2024, were analyzed and studied using various hydrogeological tools, multivariate statistical analyses, and water quality assessment methods. These include the Piper diagram, hydrochemical facies evolution diagram (HFE-D), Principal Components Analysis (PCA), correlation analysis, stable isotope analysis, Water Quality Index (WQI), and USSL diagrams. The results indicated that all surface water and pore groundwater samples were categorized as Na-Cl type, exhibiting high Total Dissolved Solids (TDS) and Electrical Conductivity (EC) values, characteristics that render them poor to unsuitable for drinking and irrigation purposes. The fracture groundwater is predominantly of the Ca-Na-Cl mixed type, with average suitability for irrigation and a limited proportion (22.5%) deemed suitable for drinking. Seawater intrusion, primarily through the surface water system, and the impact of human activities were identified as the predominant controlling factors con-tributing to the degradation of the local groundwater environment. Field empirical investigations further validated the results derived from hydrogeological assessments, multivariate statistical analyses, and isotopic approaches. The long-term shifts in hydrochemical properties, along with the latent threat of seawater intrusion, exhibit an upward trend during the dry season and show a certain degree of mitigation during the wet season. This study highlights that field investigations, in conjunction with hydrochemical tools, multivariate statistical analyses, and stable isotope analysis, can successfully furnish reliable insights into the predominant mechanisms governing regional groundwater evolution within the context of long-term and intricate envi-ronmental settings. [ABSTRACT FROM AUTHOR]

Background: Evolutionary radiation is widely recognized as a mode of species diversification, but the drivers of the rapid diversification of fungi remain largely unknown. Here, we used Amanitaceae, one of the most diverse families of macro-fungi, to investigate the mechanism underlying its diversification. Results: The ancestral state of the nutritional modes was assessed based on phylogenies obtained from fragments of 36 single-copy genes and stable isotope analyses of carbon and nitrogen. Moreover, a number of time-, trait-, and paleotemperature-dependent models were employed to investigate if the acquisition of ectomycorrhizal (ECM) symbiosis and climate changes promoted the diversification of Amanitaceae. The results indicate that the evolution of ECM symbiosis has a single evolutionary origin in Amanitaceae. The earliest increase in diversification coincided with the acquisition of the ECM symbiosis with angiosperms in the middle Cretaceous. The recent explosive diversification was primarily triggered by the host-plant switches from angiosperms to the mixed forests dominated by Fagaceae, Salicaceae, and Pinaceae or to Pinaceae. Conclusions: Our study provides a good example of integrating phylogeny, nutritional mode evolution, and ecological analyses for deciphering the mechanisms underlying fungal evolutionary diversification. This study also provides new insights into how the transition to ECM symbiosis has driven the diversification of fungi. [ABSTRACT FROM AUTHOR]

Quantifying the degree of ecological specialization of animals is essential for understanding the evolution of resource use in changing environments. Stable isotope analysis (SIA) is a powerful tool for investigating the ecological niches of animals and providing insights into their diet. This study focused on the ecological role of two coastal species of ants, Camponotus morosus and Dorymyrmex goetschi, in Chile. Their seasonal isotopic niches were characterised using carbon (δ13C) and nitrogen (δ15N) analysis. This was done on El Tabito Beach, a coastal area with a pronounced seasonality. The results indicated unique niches for each species and variation between them across seasons. While C. morosus maintained a consistent niche breadth throughout the year, D. goetschi displayed a narrower niche in summer. Our analyses showed that terrestrial-derived carbon constituted the primary food resource for both species of ants, with a slight increase in the marine component in summer. Overall, the results highlight seasonal variations in isotopic signatures, niche breadth, and diet composition and underscore the importance of considering temporal dynamics in ant ecology and, in particular, in trophic interactions. [ABSTRACT FROM AUTHOR]

Stone circles of the Wielbark culture, such as those found in Grzybnica, have long fascinated researchers, who debate their function and significance. The aim of the presented study is to determine the origins and subsistence strategies of the population buried near the stone circles in Grzybnica, which may help highlight the role of these sites within Wielbark communities. For analysis, human remains from the cemetery in Grzybnica, West Pomeranian Voivodeship, Poland, were utilized. Radiocarbon dating of five samples, stable isotope analysis of carbon and nitrogen in two samples, and strontium isotope analysis in 20 cremated human remains and 12 plant samples were conducted. Radiocarbon dating confirmed the earlier dating of the site to the period between approximately 80 and 260 CE. Dietary studies indicated that the individuals buried here regularly consumed millet (mean δ13C = –17.8) and animal protein (mean δ15N = 9.5). This diet corresponds with the variability described for the Wielbark culture site in Rogowo. The strontium isotope analysis revealed significant variation between the river valley (0.7157–0.7264) and the adjacent upland (0.7109–0.7138). The isotopic values in humans were homogeneous, ranging from 0.7113 to 0.7130, indicating no outliers that might suggest the presence of migrants. The variability observed in humans corresponds with the values observed on the upland. The results suggest that the group of individuals buried in Grzybnica was a small community that sourced their food from the upland. It is possible that this community was involved in the care of the stone circles, and the circles themselves may have been places of gatherings for local communities. However, it should be noted that only about 20 % of the graves found at the site were analyzed. The lack of migrants may be due to the low mobility of this group or methodological limitations related to the post-glacial nature of the geological substrate. Alternatively, it could also be due to the limitations associated with studying cremated remains, which allow for the reconstruction of events from only about 10 years prior. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Analyst" published by the Royal Society of Chemistry. It includes a range of articles and papers on various topics related to chemistry and scientific research. Some of the topics covered include the selection of aptamers against SARS-CoV-2, insights into lipid and fatty acid metabolism, and non-invasive diagnostic tests for lung cancer. The journal also offers information on training courses and events for professional development in the field of chemistry. [Extracted from the article]

The gas chromatography-combustion isotope ratio mass spectrometry (GC/C/IRMS) confirmation procedure for prednisone (PS) and prednisolone (PSL) is still a great challenge for the doping control laboratory due to the many structurally similar steroids present in urinary matrices. This study aims to establish an innovative online two-dimensional high performance liquid chromatography (2D-HPLC) purification method for measuring the carbon isotope ratios (CIRs) and achieving the identification of the synthetic forms of these two endogenous anabolic androgenic steroids (EAASs). Initially, the one-dimensional chromatographic column was used to separate and purify endogenous reference compounds (ERCs), and the co-elution fluids containing PS and PSL were switched to a two-dimensional chromatographic column for further purification through an online transfer system. Then the purified compounds were analyzed using GC/C/IRMS after sample pretreatments. The results showed that the minimum detection concentration of PS and PSL reached 30 ng mL−1, and no isotope fractionation occurred during the entire collection and preparation process. This method has been validated with the WADA technical document and showed good sensitivity and selectivity, demonstrating its practical applicability for urine samples in doping control laboratories. [ABSTRACT FROM AUTHOR]

In temperate ecosystems, resource availability fluctuates seasonally due to changes in environmental conditions and productivity. Intra‐ and inter‐specific trophic niche overlap under resource limitation is a measure of competitive interactions and influences species coexistence and community dynamics, but patterns of this overlap are influenced by anthropogenic activities. To investigate seasonal trophic niche dynamics of coexisting fish species in a flow‐altered river, we analysed prey resources, stomach content samples and stable isotope signatures of mottled sculpin Cottus bairdii and juvenile brown trout Salmo trutta in the Blue River, Colorado, USA, a high‐elevation oligotrophic river. Prey biomass (i.e. benthic macroinvertebrates) peaked in spring and declined through summer and autumn. Stomach content and stable isotope analysis results showed that diet composition of mottled sculpin and brown trout varied seasonally in response to changes in prey availability. Stomach content analysis results revealed that in autumn, both species exhibited the highest frequency of empty stomachs and expanded population trophic niches due to increased inter‐individual diet variation despite decreased individual trophic niche breadth. Inter‐specific trophic niche overlap was relatively high across all seasons, but the lowest degree of overlap occurred in autumn of both years when prey availability was lowest. Isotopic analysis revealed similar trends to stomach content analysis, of wider isotopic niches and reduced overlap in autumn compared to spring. Our data indicated that seasonal variation affected individual‐ and population‐level trophic niche dynamics and inter‐specific niche overlap between mottled sculpin and brown trout. This trophic segregation under resource limitation may serve as a mechanism that facilitates species coexistence in a flow‐regulated, oligotrophic river. [ABSTRACT FROM AUTHOR]

Simple Summary: Most of the ecosystems around the world are experiencing high levels of stress. Invasive species are one of the major threats to biodiversity. To successfully prevent and manage this conservation issue, a good understanding of ecological and biological processes involving the native and introduced species is required. This is often challenging due to the interaction of many stressors within an ecosystem, hindering direct changes caused by the invader. Here, we present a unique situation where an invading snow crab is the only disturbing factor in the benthic ecosystem of an arctic fjord. This study looks at how the crabs' feeding habits change as the invaded ecosystem degrades due to their foraging. Stomach content and stable isotope analyses have revealed that while the prey items have changed, and crabs are forced to feed on less accessible and less nutritional food, their trophic position has not altered. Changes in feeding habits have occurred within the same trophic level. Following the depletion of most nutritional prey items, the number of crabs in the bay has collapsed. We expect a further decrease in crab numbers, a possible partial restoration of the benthic community, and a repeat of the cycle after new settlements of young crabs. The introduction of a new species can lead to substantial changes in a new ecosystem. Local and introduced species' survival depends on their ability to adapt to the new environment. Studying such adaptations is often hindered by multiple factors affecting the ecosystem. The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea, is a unique invasive species affecting an otherwise undisturbed ecosystem. The crab has caused drastic changes in the macro- and megabenthic taxonomic structure, abundance, and biomass of the most common species in an Arctic fjord, Blagopoluchiya Bay. Stomach content and stable isotope analysis were applied to study crabs' feeding habits. As the abundance of the most common prey items diminished, the crabs switched to other less accessible food. Prior to substantial changes in benthic communities, the diet of the snow crabs was similar to that of other invaded and native areas, where animal food predominates. However, with the degradation of the ecosystem, detritus contribution has substantially increased. The changes in prey items did not change the crab's trophic status, and they continued to feed within the same trophic niche. In the depleted benthic communities of Blagopoluchiya Bay, the snow crab is forced to use all available food sources. [ABSTRACT FROM AUTHOR]

Significance Statement: This work analyses multi‐omics and stable isotope labeling data and provides a comprehensive overview on C3‐plant acclimation to high light. We show that Arabidopsis thaliana in abscene of a clockwise TCA cycle accumulates large amounts of C4 acids in vacuoles, which form a secondary pool of reduced carbon that exceeds the plastidic accumulation of carbon in form of starch. [ABSTRACT FROM AUTHOR]

The introduction of non-native fish species poses a significant threat to biodiversity. In Spain, the common carp Cyprinus carpio (Linnaeus, 1758) and the bleak Alburnus alburnus (Linnaeus, 1758) are both established and sometimes co-occurring non-native species. Here, we investigated the trophic ecology of these species using an integrative approach, combining dietary and stable isotope analyses, to understand seasonal variations in their feeding ecology and potential niche overlap. We found a variable pattern for the gonadosomatic index of the two species in spring and autumn, suggesting the occurrence of extended reproductive periods for both A. alburnus and C. carpio. The gut content and isotopic niche analyses showed seasonal niche shifts, as well as interspecific niche partitioning and potential feeding competition. Notably, we found remains of small fish in the gut of both species and one entire individual of Gambusia holbrooki (Girard, 1859) in the carp gut, highlighting the potential of both species to prey also upon native fish fry or juveniles. Moreover, A. alburnus showed an ontogenetic shift toward prey from higher trophic levels and from the littoral/benthic environment, while C. carpio showed an increase in the proportion of prey from the pelagic environment with size. [ABSTRACT FROM AUTHOR]

Increasingly frequent severe drought events are pushing Mediterranean forests to unprecedented responses. Lack of management leads to dense forests that are highly susceptible to drought stress, potentially resulting in extensive dieback and increased vulnerability to other disturbances. Forest treatments like thinning and slash burning reduce competition for resources and have the potential to enhance tree growth and vigor and minimize tree vulnerability to drought. Here, we used tree rings to study the growth and physiological response of black pine (Pinus nigra) to drought in northeastern Spain under different treatments, including two thinning intensities (light and heavy, with 10% and 40% basal area reduction, respectively) followed by two understory treatments (clearing alone and in combination with slash burning), resulting in a research design of four treatments plus an untreated control with three replicates. Specifically, we studied basal area increment (BAI), resilience indices, and intrinsic water use efficiency (iWUE) using carbon and oxygen isotope composition (δ13C and δ18O in tree‐ring cellulose) before and after treatments. Our results showed that BAI and resistance to drought increased in the heavy‐thin (burned and unburned) and light‐thin burned units. Resilience increased in the burned units regardless of the thinning intensity, while recovery was not affected by treatment. Slash burning additionally increased BAI in the light‐thin and resistance and resilience in the heavy‐thin units compared with clearing alone. The stable isotope analysis revealed a minor effect of treatments on δ13C and δ18O. No change in iWUE among treatments was presumably linked to a proportional increase in both net CO2 assimilation and stomatal conductance, which particularly increased in the heavy‐thin (burned and unburned) and light‐thin burned units, indicating that these trees were the least affected by drought. This study shows that management approaches aimed at reducing wildfire hazard can also increase the vigor of dominant trees under drought stress. By reducing competition both from the overstory and the understory, thinning followed by clearing alone or in combination with slash burning promotes tree growth and vigor and increases its resistance and resilience to drought. [ABSTRACT FROM AUTHOR]