Carbon Isotope Analysis Research Articles

Osteological, multi-isotope and proteomic analysis of poorly-preserved human remains from a Dutch East India Company burial ground in South Africa

Skeletal remains discovered in Simon’s Town, South Africa, were hypothesised as being associated with a former Dutch East India Company (VOC) hospital. We report a novel combined osteological and biochemical approach to these poorly-preserved remains. A combined strontium (87Sr/86Sr), oxygen (δ18OVPDB) and carbon (δ13CVPDB) isotope analysis informed possible childhood origins and diet, while sex-specific amelogenin enamel peptides revealed biological sex. Osteological analyses presented evidence of residual rickets, a healed trauma, dental pathological conditions, and pipe notches. The combined isotope analyses yielded results for 43 individuals which suggested a diverse range of geological origins, including at least 16% of the population being non-local. The inclusion of δ13CVPDB had intriguing implications for three individuals who likely did not have origins in the Cape Town region nor in Europe. Peptide analysis on the dental enamel of 25 tested individuals confirmed they were all biologically male. We suggest that isolated enamel may provide crucial information about individuals’ pathological conditions, geographical origins, diet, and biological sex. These data further demonstrated that a combined approach using multiple osteological and biochemical methods is advantageous for human remains which are poorly preserved and can contextualise a site with little direct evidence.

Neolithic herding practices in the Southern Caucasus: Animal management in the early 6th millennium BCE at Masis Blur in Armenia’s Ararat Valley

The Southern Caucasus is traditionally an important area of livestock production and a key region in the spread of herding from southwestern Asia to Eurasia’s western steppe. Neolithic settlements appeared across the Southern Caucasus in the early 6th millennium BCE. How these communities used the landscape and managed livestock in the context of mixed farming is not well understood. Stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of bone collagen and stable carbon and oxygen (δ18O) isotope analysis of tooth enamel from faunal remains from Masis Blur, one of the earliest Neolithic sites in the Southern Caucasus, clarify how communities maintained herds in this topographically varied region. δ13C and δ15N values indicate hunting wild fauna in diverse environments. δ13C and δ18O values from sequentially sampled livestock teeth demonstrate markedly different strategies for managing cattle and caprines. Negative covariation in δ18O and δ13C values in most caprines suggest seasonal mobility to C3-dominated high elevation pastures in the summers, and/or winter foddering with water-stressed C3 or wild C4 plants. These seasonal strategies were in place in the earliest known phase of occupation at Masis Blur, indicating that Southern Caucasus Neolithic communities likely exploited a range of environments linking the lowland plains and mountainous zones.

Unprecedented shift in Canadian High Arctic polar bear food web unsettles four millennia of stability

Stable carbon (δ13C) and nitrogen (δ15N) isotope analysis was conducted on modern and archaeological polar bear bone collagen from the Canadian Arctic Archipelago to investigate potential changes in polar bear foraging ecology over four-millennia. Polar bear δ13C values showed a significant decline in the modern samples relative to all archaeological time-bins, indicating a disruption in the sources of production that support the food web, occurring after the Industrial Revolution. The trophic structure, indicated through δ15N, remained unaltered throughout all time periods. The lower δ13C observed in the modern samples indicates a change in the relative importance of pelagic (supported by open-water phytoplankton) over sympagic (supported by sea ice-associated algae) primary production. The consistency in polar bear δ13C through the late Holocene includes climatic shifts such as the Medieval Warm Period (MWP, A.D. 950-1250) and the early stages of the Little Ice Age (LIA, A.D. 1300-1850). These findings suggest that polar bears inhabit a food web that is more pelagic and less sympagic today than it was through the Late Holocene. We suggest that modern, anthropogenic warming has already affected food web structure in the Canadian Arctic Archipelago when modern data are contextualized with a deep time perspective.

Sources of intraspecific variation in the isotopic niche of a semi-aquatic predator in a human-modified landscape.

Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of Caiman crocodilus in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (δ13C and δ15N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.

Canopy Leaching Rather than Desorption of PM2.5 From Leaves Is the Dominant Source of Throughfall Dissolved Organic Carbon in Forest

AbstractDissolved organic carbon (DOC) in throughfall plays a vital role in providing carbon and energy to organisms in forests. We utilized carbon isotope analysis to allocate the sources of throughfall DOC, including leaching from plant tissues, PM2.5 deposition on plant foliage, and precipitation. Rainwater, PM2.5, and throughfall samples were collected from pine and oak forests between March and November 2021. The mean concentration of throughfall DOC was 7.9 mg L−1, approximately six times higher than that of rainfall. The mean Δ14C of throughfall DOC was −38.2‰, ∼200‰ higher than that of rainwater or PM2.5. Mass balance estimates revealed that canopy leaching contributed to ∼83% of throughfall DOC, while desorption of PM2.5 and rainwater accounted for only ∼3% and ∼14% of throughfall DOC, respectively. These results clearly highlight canopy leaching as the primary source of carbon input to the forest floor, with a relatively minor contribution from PM2.5 desorption on leaves.

Carbon and oxygen isotope characteristics of carbonate rocks in the Mesoproterozoic Jixian System of the Ordos Basin and their implications

The paleoenvironment of Jixian carbonate rocks in the Mesoproterozoic Ordos Basin is studied by carbon and oxygen isotope analyses, diagenetic environment analysis, and the restoration of paleosalinity and paleotemperature. The results indicate that the carbonate rocks of the Jixian System have always been in a near-surface environment and have not been deeply buried. The ranges of variation in δ13CPDB and δ18OPDB are relatively narrow, ranging from − 5.75 to 1.41‰ and − 8.88 to − 4.01‰, respectively, which is consistent with the stable tidal flat sedimentary environment during the Mesoproterozoic in the study area. The paleosalinity (Z) values range from 111.7 to 127.1, and the paleotemperature (T) values range from 32.7 to 57.33 °C, indicating a relatively warm paleoclimatic environment during the Mesoproterozoic era in the study area. The analysis shows that in a warm paleoclimatic environment, although carbon and oxygen isotopes, Z, and T have certain fluctuations, their ranges are relatively small, reflecting to some extent the stable tectonic environment of the study area during the Mesoproterozoic era. Comprehensive research shows that the Ordos Basin had a warm climate and a stable tectonic environment in the Mesoproterozoic, which may be a good response to the North China Block's position near the equator and continuous thermal subsidence in the Mesoproterozoic.

The food culture of the Iron Age nomadic elite from the ‘Valley of the Kings’ in Tuva: radiocarbon dating, stable carbon and nitrogen analysis of the Chinge Tey barrows (Turan-Uyuk Basin, Russia)

Subsistence strategies of Eurasian pastoral populations have been broadly studied in the archaeological literature. The 'Valley of the Kings' in Tuva, Russia, has captivated archaeologists with its remarkable collection of large burial mounds, containing lavishly equipped tombs of nomadic kings, warlords, and aristocracy. These barrows bear witness to the ancestral connections between the deceased leaders, highlighting the alliances among prehistoric nomads in Central Asia. In this research, we present comprehensive radiocarbon dating and δ13C/δ15N isotopic data from the Chinge Tey barrows, which represent the burial sites of 12 high-ranking individuals. The chronological alignment of both Chinge Tey monuments with the Arzhan 1 and Arzhan 2 reference frames sheds light on their historical context. This study delves into intricate aspects of ecological adaptability, pastoral food practices, social hierarchies, and nomadic mortuary rituals. Analysis of carbon and nitrogen stable isotopes indicates potential connections between the barrows in the 'Valley of the Kings' and diverse nomadic cultures, suggesting that dietary habits among neighboring populations may have exhibited significant variation.

Pre-treatment methods for stable oxygen and carbon isotope analyses of structural carbonates of bones in marine teleost fishes.

Although the proportion of structural carbonates in vertebrate bones is low, the values of isotopes, namely stable oxygen (δ18 O) and carbon (δ13 C), in structural carbonates provide environmental and physiological information, which can be beneficial for estimating the palaeontological and ecological parameters of vertebrates. However, a few studies have analysed the isotopes of structural carbonates in modern teleost fishes, and a well-developed protocol for sample preparation is lacking. We examined different pre-treatment methods of preparing bone samples of three marine teleost fishes (Japanese flounder, Pacific bluefin tuna and yellowtail) and investigated the effects of the cleaning methods on the stable isotope values of structural carbonates among vertebrae in the same individual. Isotope values were analysed using isotope ratio mass spectrometry. Physical cleaning was the most promising pre-treatment method and resulted in δ18 O values that were comparable to those of otoliths. Chemical treatments with NaOH and H2 O2 changed the percentage of structural carbonates in the bone and affected δ18 O and δ13 C values. High-temperature treatments, such as boiling and roasting, altered δ18 O values due to the exchange of oxygen with environmental water or vapour. Our results suggest that chemical cleaning methods used to prepare bone phosphate or collagen samples for isotope analyses are not suitable for structural carbonates. Physical cleaning is the appropriate pre-treatment method for analysing the isotopes of structural carbonates. Also, we emphasise that standardising the vertebral number is necessary to make δ13 C values comparable between specimens in the same species.

Analysis of intramolecular carbon isotope distributions in alanine by electrospray ionization Orbitrap mass spectrometry

The ability to detect intramolecular isotopic differences within a single molecule can answer questions about molecule synthesis and alteration across numerous scientific fields. Until recently, intramolecular (i.e., position-specific isotope analysis, PSIA) isotope measurements were laborious, requiring large amounts of analyte or specialized instrumentation. Orbitrap™ mass spectrometers are capable of fragmenting molecules and have the high mass resolution needed to constrain position-specific isotopic differences among the resulting fragment ions. Orbitrap mass spectrometers with electrospray ionization accurately measured the molecular average isotope composition of acetate, nitrate, sulfate, phosphate, and the amino acid methionine, as well as the position-specific isotopic structure of methionine. Here, we document the ability of this method to measure the position-specific carbon isotope structure of the amino acid alanine. Data include measurements of 13C-enriched materials to assign specific atoms in fragments to the original molecular structure and detect any recombination of atoms in resultant fragments. We further demonstrate high-precision intramolecular isotope analyses for standards with independently determined position-specific carbon isotope compositions. Isotope data from ESI-Orbitrap-MS agrees with values obtained using gas source isotope ratio mass spectrometry, giving further confidence to this novel approach to PSIA. The carbon isotope analyses by Orbitrap-MS were rapid and required ∼5 μg of analyte to obtain both molecular average and position-specific values in triplicate with precision ≤1‰.

Using stable carbon isotope ratio analysis to detect adulteration in red yeast rice dietary supplements

Red yeast rice (RYR) is marketed as a dietary supplement because it contains natural 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), including monacolin K. However, there is concern that some RYR supplements may be adulterated with the pharmaceutical drug lovastatin to enhance health claims. We have developed an optimized method to isolate monacolin K/lovastatin from complex RYR dietary supplement matrices to then test for adulteration in RYR supplements using stable carbon isotope (δ13C) analysis. Samples were initially screened for monacolin K/lovastatin using liquid chromatography with mass spectrometric detection (LC-MS). To ensure the extraction process did not affect the measured isotopic values (i.e., isotopic fractionation effects), neat lovastatin standards were spiked into two types of blank RYR matrices (powder and gel). The monacolin K/lovastatin peaks were detected using high performance liquid chromatography with ultraviolet detection (HPLC-UV) and isolated using fraction collection. Residual matrix components were removed from targeted fractions by solid phase extraction (SPE) using graphitized carbon black cartridges. The resulting isolates were then analyzed using elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) to measure δ13C values. The δ13C values of the extracted lovastatin standards were compared to their respective neat lovastatin δ13C values and demonstrated negligible isotopic fractionation effects. Using this optimized clean up method and carbon isotope analysis, thirty-one samples were screened. Eight RYR dietary supplement samples had >0.8 mg/g of monacolin K/lovastatin, our minimum threshold for analyzing samples using this method. Four of these eight samples had δ13C values greater than −28.3‰, a previously proposed cutoff value for natural monacolin K, indicating likely adulteration. Additionally, five RYR powder samples were analyzed as part of a collaborative study using in-house methods from two laboratories and the data shows acceptable agreement in the δ13C values of monacolin K/lovastatin (differences ranging from ±0.02‰ to ±0.76‰). This optimized method represents a robust, reproducible procedure for detecting lovastatin adulteration in dietary supplements with minimal isotopic fractionation.

Weak seasonality in benthic food web structure within an Arctic inflow shelf region

The Arctic Ocean is characterized by pronounced seasonality in the quantity and quality of organic matter exported from the surface ocean. While it is well established that changes in food availability can alter the abundance, biomass and function of benthic organisms, the impact on food web structure is not well studied. We used bulk carbon and nitrogen stable isotope analysis to assess the quantity and quality of sediment organic matter and structure of the benthic food web in four seasons within the Northern Barents Sea (76°N − 82 °C). Despite a highly seasonal vertical flux, we found that the organic carbon and chlorophyll-a content of surface sediments was seasonally stable, suggesting a lack of seasonality in food availability at the seafloor. However, organic biomarkers indicate that the quality of sediment organic matter increased to a maximum in August and December, up to 6 months after the spring bloom. The seasonal stability of food quantity was mirrored in food-web structure (e.g., total isotopic range, number of trophic levels) which did not change significantly across sampling periods. We expected that suspension and deposit feeders would respond more readily to seasonal changes in food quality compared to predators. However, we observed no significant seasonal changes in the trophic levels or isotopic niche areas of benthic functional groups. The centroids of isotopic niches of all benthic functional groups shifted seasonally by <2 ‰ along the δ13C-axis, suggesting minimal shifts in carbon resource use. Because the northern Barents Sea experiences significant changes in seasonal sea ice cover, we expected that stable-isotope ratios of benthic organisms would show an increased consumption of sympagic-derived organic matter through less negative δ13C values in early spring and summer. However, only two taxa (the soft coral Gersemia spp. and bivalves in the family Yoldiidae) showed 13C-enrichment in spring or summer consistent with the assimilation of sympagic-derived organic matter, despite previous evidence suggesting widespread use of this carbon source. Overall, our results show that there is an apparent de-coupling in time between pelagic processes and benthic food-webs in which the accumulation and assimilation of high-quality organic matter occurs for benthos during the fall and early winter months when there is little to no fresh organic matter generated at the surface. This temporal mismatch highlights the importance of considering the timescales over which components of the marine ecosystem respond to short-term environmental changes and the methods employed to assess seasonality.

Lipid-extracted muscle and liver tissues: Can they reveal mercury exposure of pelagic sharks?

Pelagic sharks are apex predators in oceanic ecosystems and tend to accumulate high amounts of mercury (Hg). The conventional method for assessing Hg exposure in sharks involves analyzing tissue samples without any chemical treatment. However, a substantial number of chemically treated tissue samples are still being preserved in laboratories or museums. It is critical to maximize the utilization of existing samples to reduce the need for additional sampling of pelagic sharks, especially endangered species. Lipid extraction is a widely employed pretreatment process for carbon isotope analysis in shark trophic ecology, while its impact on Hg quantification remains uncertain. Here, we evaluated the feasibility of using lipid-free muscle and liver tissues for investigation of Hg exposure in four endangered pelagic sharks inhabiting the eastern Pacific, including bigeye thresher (Alopias superciliosus), pelagic thresher (A. pelagicus), blue shark (Prionace glauca) and silky shark (Carcharhinus falciformis). Results showed that total Hg concentrations (THg) differed between untreated (THgbulk) and lipid-free (THglipid-free) samples for each tissue type of each species. In addition, dichloromethane-methanol extractions significantly altered the amount of Hg. This may result from the removal of lipoprotein compounds that vary between tissues and species. The THgbulk can be calculated by THglipid-free using the following formulas, THgbulk = 1.14 × THglipid-free + 0.30 and THgbulk = 0.33 × THglipid-free + 0.18, for muscle and liver tissues, respectively. These findings emphasize the applications of lipid-free tissues in THg analysis. This study may have important implications for improving evaluation of Hg exposure in endangered pelagic sharks.

Methane and CO2 production in the wetland Lake Podpeč (Slovenia)

PurposeThis study deals with the identification of CH4 and CO2 sources in the high-carbonate wetland Lake Podpeč in the Ljubljana Marshes, Slovenia.Materials and methodsLake Podpeč is situated on the periphery of the Ljubljana Marshes in central Slovenia. A combination of chemical analysis and natural abundance analysis of stable carbon and hydrogen isotopes of CH4, along with analysis of dissolved inorganic carbon (DIC), was employed in an incubation experiment.Results and discussionThe isotopic composition of dissolved inorganic carbon (δ13CDIC) suggests three main processes occurring during incubation: oxic degradation of organic matter (OM), anoxic OM degradation, and methanogenesis. During oxic degradation of OM, the δ13CDIC values slightly decrease from − 13.2 to − 14.5‰. However, after 50 days, the δ13CDIC values started to increase, reaching − 12.2‰ by the end of the experiment. 13C enrichment coincided with the formation of CH4, which began to increase simultaneously. The CH4 produced had an average δ13CCH4 value of − 67 ± 1‰ and δ2HCH4 value of − 389 ± 3‰, suggesting that CH4 is formed through acetate fermentation. The contribution of calcite dissolution to DIC increased during the degradation of OM by 53%. However, during methanogenesis, there was no significant change in the concentrations of Ca, and the estimated contribution to DIC was only 3%.ConclusionsThis study enhances our understanding of methane production in wetland Lake Podpeč and its relevance in the context of other high-carbonate lakes. The findings offer insights into the complex interactions between OM degradation, methane production pathways, and carbonate dissolution, which has implications for the global carbon cycle and greenhouse gas emissions.

Generation, accumulation, and distribution of Upper Paleozoic tight sandstone gas in the northeastern margin of the Ordos Basin

Tight sandstone gas in the Upper Paleozoic strata of the northeastern margin of the Ordos Basin exhibits remarkable exploration potential. The objective of this study is to characterize the generation, accumulation, and distribution of Upper Paleozoic tight sandstone gas in the Linxing–Shenfu gas fields located on the northeastern margin of the Ordos Basin. This study uses the following approaches: (1) porosimetry and permeability testing; (2) stable carbon isotope analysis; (3) organic geochemical examination; (4) gold tube pyrolysis experiments; (5) basin modeling; (6) fluid inclusion analysis; and (7) drilling and seismic data analysis. Reservoirs are classified based on the distance between the sandstone traps and source rocks: in Type I reservoirs, the sandstone traps are interbedded with the source rocks; in Type II reservoirs, the sandstone traps immediately overlie the source rocks; and in Type III reservoirs, the sandstone traps are located far from the source rocks. The three types of gas-bearing reservoirs in the Linxing–Shenfu gas fields formed between 190 Ma and 96 Ma (Early Jurassic to Late Cretaceous), and gas accumulation in the three types of reservoirs occurred during the same period. A pressure differential was created between the source rocks and neighboring sandstones as a response to gas generation, and this was the primary mechanism of gas migration and accumulation in the Type I and Type II reservoirs. The initiation and growth of the vertical faults enabled the gas to migrate from the deep source rocks along faults, eventually accumulating in the Type III reservoirs; additionally, the gas migration and accumulation were primarily driven by buoyancy. Type I reservoirs with high gas saturation was mainly distributed in regions with gas expulsion intensities greater than 7 × 108 m3/km2 and located away from the faults. Type II reservoirs with high gas saturation were predominantly distributed in regions with gas expulsion intensities greater than 10 × 108 m3/km2. Type III reservoirs with gas production capacity primarily distributed in conventional sandstone units with high reservoir quality near the faults.

Salt marsh expansion into estuarine mangrove mudflats reduces nitrogen removal capacity

Salt marsh (Spartina alterniflora) has been rapidly encroaching into mangrove wetlands worldwide. However, the potential effects of salt marsh expansion on coastal nitrogen cycling and ecosystem function remain unclear. In this study, sediment cores were seasonally collected from mangroves, salt marshes and mudflats from 2020 to 2021 to assess their nitrogen cycling. Nitrogen transformation rates of mineralization, immobilization, nitrification, denitrification, anaerobic ammonium oxidization (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were determined using 15N isotope tracer techniques. Rate measurements were paired with analysis of physicochemical properties, carbon isotopes, and nitrogen functional genes. The results showed that compared to mangrove sediments, salt marsh sediments mostly exhibited lower mineralization and denitrification rates but higher nitrification rates. Mudflat sediments had the lowest mineralization and denitrification rates among the studied habitats, while the nitrification rates were close to those of salt marshes. The differences in carbon quantity and source, nitrogen gene abundances, and carbon and nitrogen substrate availabilities controlled the variations in nitrogen transformation rates. The balance of these rates was used to indicate the net nitrogen retention or removal capacity of the three habitats. On an annual scale, salt marshes exhibited ammonium (NH4+-N) removal while mangroves had net NH4+-N retention. Nitrate (NO3--N) was removed both in salt marsh and mangrove sediments with larger removal capacity in mangroves. Salt marsh sediments had lower NH4+-N removal but higher NO3--N removal levels than mudflat sediments. In summary, salt marsh invasion decreased the overall nitrogen removal levels in the mangrove-mudflat wetland. The future scenarios of increasing salt marsh coverage suggest a decreased removal of nitrogen loads, which has important implications for mitigating coastal eutrophication.

Seasonal variation in trophic structure and community niche dynamics of an Arctic coastal community of marine vertebrates

Temporal variation in food web structure is widespread among highly seasonal environments, such as the Arctic, and is driven by changes in resource availability. Variation in resource availability can lead to species differences in diet composition, isotopic niche width, and trophic position (TP) across seasons. Here, we used tissue samples that represent two distinct turnover rates for diet (liver = shorter term, muscle = longer term) from 18 fish and three marine mammal species to investigate seasonal (i) variation in TPs within the Southampton Island marine ecosystem of Hudson Bay, (ii) variation in consumer isotopic niche width within this part of the food web, and (iii) variation in community niche dynamics among a fish and marine mammal community using stable carbon (δ13C) and nitrogen (δ15N) isotope analyses. Many zooplanktivores and piscivores increased in TP in summer (i.e., shorter-term turnover period), whereas benthic feeders dependent on ice-obligate prey decreased in TP. Most isotopic niche widths and community metrics (δ15N range, total ellipse area, mean centroid distance) were higher in liver than muscle. Our findings demonstrate seasonal changes in TPs, which suggests that Arctic communities may be differentially affected by longer ice-free periods and earlier onset of primary production due to accelerated climate change.

Análisis isotópico seriado de una muestra de cabello del individuo inhumado en el volcán Quehuar (Salta, Argentina)

In 1999 the frozen remains of a young female individual of Inca affiliation were found on the summit of volcano Quehuar (Salta, Argentina) at an elevation of 6130 masl. The individual, part of a capacocha ritual, was partially destroyed due to a dynamite explosion executed by looters. In this work, the stable isotope analysis of carbon and nitrogen on a serial sample of hair is presented and discussed to investigate the eating patterns of the last year and a half of the individual's life. The results indicate a diet that included resources under the C4 photosynthetic pathway and slight dietary variation during the period considered. These results constitute a contribution to the reconstruction of the life histories of the individuals associated with high-altitude Inca burials, accounting for the diversity of experiences they went through in the months before their death.

Exploitation shifted trophic ecology and habitat preferences of Mediterranean and Black Sea bluefin tuna over centuries

AbstractDuring recent decades, the health of ocean ecosystems and fish populations has been threatened by overexploitation, pollution and anthropogenic‐driven climate change. Due to a lack of long‐term ecological data, we have a poor grasp of the true impact on the diet and habitat use of fishes. This information is vital if we are to recover depleted fish populations and predict their future dynamics. Here, we trace the long‐term diet and habitat use of Atlantic bluefin tuna (BFT), Thunnus thynnus, a species that has had one of the longest and most intense exploitation histories, owing to its tremendous cultural and economic importance. Using carbon, nitrogen and sulphur stable isotope analyses of modern and ancient BFT including 98 archaeological and archival bones from 11 Mediterranean locations ca. 1st century to 1941 CE, we infer a shift to increased pelagic foraging around the 16th century in Mediterranean BFT. This likely reflects the early anthropogenic exploitation of inshore coastal ecosystems, as attested by historical literature sources. Further, we reveal that BFT which migrated to the Black Sea–and that disappeared during a period of intense exploitation and ecosystem changes in the 1980s–represented a unique component, isotopically distinct from BFT of NE Atlantic and Mediterranean locations. These data suggest that anthropogenic activities had the ability to alter the diet and habitat use of fishes in conditions prior to those of recent decades. Consequently, long‐term data provide novel perspectives on when marine ecosystem modification began and the responses of marine populations, with which to guide conservation policy.

Early childhood nurturing strategies in groups of the Yellow River's middle reaches from the late Yangshao culture (3500–2800 BCE): A stable isotope perspective

AbstractWe have reconstructed the feeding patterns, weaning age, dietary structure, and physiological stress experienced by the late Yangshao culture (3500–2800 BCE) of the Middle Yellow River in different individuals early years through comparative carbon and nitrogen stable isotope analyses of dentin incremental sections, limb bones, or rib assemblages. We present dentin incremental and bone collagen δ13C and δ15N isotope data from 17 individuals from two late Yangshao culture archeological sites (Qingtai 青台 and Shuanghuaishu 双槐树). The result showed that all individuals in the sample weaned between 2.5 and 3.8 years old, and other than the fact that females weaned slightly sooner than males in the Qingtai sites, there were no sex variations in dietary trends across life history stages. The majority of individuals consistently consumed C4 foods (millets) from early childhood onward. A small number of individuals consumed both C3 and C4 foods at an early age, and the proportion of C3 foods (rice) consumed declined or gradually disappeared with increasing age. In addition to the traditional local foods based on millets, a small number of individual families added rice, a newly accessible resource, in varying proportions for young children's foods, which has directly contributed to the dichotomy within this research group in terms of dietary patterns and child‐rearing concepts. The emergence of early childhood nurturing strategies in this study serves as a significant microcosm of the social context in which individual families, private ownership, and civilization progressively took shape in early China.

Lignin analysis of sediments from around 2,000 to 1,000 years ago (Jiulong River estuary, southeast China)

Abstract In this work, a sediment core collected from the Jiulong River estuary in southeastern China was subjected to 14C dating of foraminifera, as well as lignin, total organic carbon, and stable carbon isotope (δ13C) analyses in order to determine the impacts of climate change and human activities on the sedimentary organic matter in this area from around 2,000 to 1,000 years ago. The ratios of lignin parameters syringyl/vanillyl and cinnamyl/vanillyl ranged from 1.60 to 8.63 and 0.11 to 0.45, respectively, and the lignin phenol vegetation index ranged from 25.14 to 1740.14, indicating the presence of non-woody angiosperms. The ratio of vanillic acid/vanillin ranged from 0.42 to 2.04, indicating medium to high degrees of oxidative degradation. The vertical distribution profile showed a similar historical sedimentary trend with locations at higher latitudes along the Zhejiang-Fujian Mud Area, with the lower abundance of total lignin from around 2400 to 2000 BP being attributed to the decreasing temperature during this period. However, all the lignin parameters showed higher values and greater fluctuations due to increasing temperatures after 2000 BP, and human activity has probably had the greatest impact in the most recent 1,000 years.