This paper describes devices to extract α-cellulose from small whole wood samples developed at the Lamont-Doherty Earth Observatory Tree-Ring Lab and explains the procedures for chemical extractions ...and for the dual analysis of carbon (δ13C) and oxygen (δ18O) stable isotopes. Here, we provide the necessary steps and guidelines for constructing a cellulose extraction system for small amounts of wood and leaves. The system allows the simultaneous extraction of cellulose from 150 samples by means of in-house filter tubes, where chemicals used for the cellulose extraction are exchanged and eliminated in batches. This new implementation diminishes the processing time, minimizes physical sample manipulation and potential errors, increases sample throughput, and reduces the amount of chemicals and analytic costs. We also describe the dual measurement of δ13C and δ18O ratios in tree-ring cellulose using high-temperature pyrolysis in a High Temperature Conversion Elemental Analyzer (TC/EA) interfaced with a Thermo Delta V plus mass spectrometer.
Determining diet is a key prerequisite for understanding species interactions, food web structure and ecological dynamics. In recent years, there has been considerable development in both the ...methodology and application of novel and more traditional dietary tracing methods, yet there is no comprehensive synthesis that systematically and quantitatively compares the different approaches.
Here we conceptualise diet tracing in ecology, provide recommendations for method selection, and illustrate the advantages of method integration. We summarise empirical evidence on how different methods quantify diet mixtures, by contrasting estimates of dietary proportions from multiple methods applied to the same consumer‐resource datasets, or from experimental studies with known diet compositions.
Our data synthesis revealed an urgent need for more experiential comparisons among the dietary methods. The comparison of diet quantifications from field observations showed that different techniques aligned well in cases with less than six diet items, but diverged considerably when applied to more complex diet mixtures.
Efforts are ongoing to further advance dietary estimation, including how reliably compound specific stable isotope analyses and fatty acid profiles can quantify more prey items than bulk stable isotope analyses. Similarly, DNA analyses, which can depict trophic interactions at a higher resolution than any other method, are generating new ways to better quantify diets and differentiate among life‐stages of prey. Such efforts, combined with more empirical testing of each dietary method and establishment of open data repositories for dietary data, promise to greatly advance community and ecosystem ecology.
The arrival of Bison in North America significantly affected competitive relationships among herbivores and may have played an important role in the eventual extinction of contemporaneous Pleistocene ...megafaunal taxa. To investigate the dietary ecology of fossil bison and examine the potential for such an ecological impact, we analyzed the stable carbon and oxygen isotope composition of Bison latifrons and Bison antiquus tooth enamel from four regions with distinct climatic settings and vegetation. Newly sampled regions include American Falls, Idaho; Diamond Valley Lake, California; Central Florida; and Snowmastodon, Colorado. The Snowmastodon site contains the highest elevation assemblage known to contain B. latifrons. We compared this new isotopic dataset to all available published isotopic data for Pleistocene Bison sp.
B. latifrons and B. antiquus were found to have isotopically similar diets when recovered from the same regions. Both species of bison consumed C4 vegetation but incorporated significant proportions of C3 plants into their diets based on mean δ13C values. Independent paleobotanical records support the interpretation that the majority of specimens exhibited mixed feeding behavior. We detected statistically significant differences in bison diets between regions that correspond to mean annual temperatures. Serial oxygen sampling indicates different degrees of seasonal variation in the meteoric waters consumed by bison in each of the newly sampled regions. Bison from Diamond Valley Lake and Snowmastodon exhibit the strongest signals of seasonal differences in vegetation consumption, while animals from American Falls and Central Florida consumed similar vegetation year-round. Our results confirm the hypothesis that Pleistocene Bison exhibited more malleable dietary and habitat requirements than previously assumed. This dietary plasticity allowed Pleistocene bison to compete with other species of the North American megafauna until their eventual replacement by the modern Bison bison.
•Fossil bison consumed C4 vegetation but incorporated significant proportions of C3 plants into their diets when available.•Pleistocene bison from California and Colorado exhibit strong signals of seasonal variation in vegetation consumption.•Fossil bison from Idaho and Central Florida exhibit isotopic signals indicating consistent diets year-round.•Isotopic data from new localities indicate a wide range of climate conditions and dietary flexibility in Pleistocene bison
•Spatial and temporal variability of benthic isotopic niches were investigated.•Food web structure follows the patterns of organic matter quantity and quality.•Higher organic matter supply supports ...food web diversity and benthic carnivory.•Spatio-temporal food-web structure is a good indicator of ecosystem function.
The quantity and quality of organic matter (OM) available for macrobenthos vary on temporal and spatial scale, especially in coastal areas, where the seafloor is supplied by both seasonal pulses of primary production and terrestrial carbon transported by rivers. Human-induced environmental changes will alter OM transport to the seafloor, thus, it is of crucial importance to recognize the impacts of spatio-temporal OM variability on macrobenthic food webs. In this study, the seasonal variability of quantity and quality of OM and its effect on benthic food-web structure were studied at four locations along the southern coast of the Baltic Sea, characterized by similar species pools but different environmental settings and various scales of anthropogenic and riverine influence. Our study shows that temporal changes in the isotopic niche (δ13C and δ15N) of benthic invertebrates follow the patterns of quantity and quality of OM related to seasonal changes of pelagic primary production, riverine discharge of terrestrial OM and the input of anthropogenically enriched sources. In the semi-enclosed bay, exposed to intensive summer blooms, all feeding groups expressed lower δ15N values in autumn, suggesting the incorporation of δ15N-depleted cyanobacteria. At a location supplied by a higher proportion of OM from allochthonous sources (riverine discharge), omnivores occupied higher trophic levels, probably due to a higher abundance of meiobenthic prey. In contrast, at the open Polish coast, where the main food supply occurs during diatom spring bloom, the isotopic niche of omnivorous species showed much higher seasonal variability, underlining the importance of food availability for food-web diversity. Quick adaptation of benthic food-web structure to seasonal variations in OM properties and its modification by local conditions may indicate high plasticity of species feeding behavior that suggests a high capacity of benthic communities to mitigate ongoing changes in the marine environment, at least within the range observed today. Our results confirm that combination of spatial and temporal scales in sampling of the food-web structure is a good indicator of the ecosystem stability and function.
Oceanic basalts show variation in their iron and magnesium isotope compositions. One hypothesis for the origin of this is source variation: radiogenic isotope and trace element abundance studies have ...long argued that the Earth's upper mantle is geochemically heterogeneous and that subducted crust is a major contributor to this diversity. In contrast, a recent hypothesis posits that stable isotopes record disequilibrium during melt transport and so provide novel insight into the melting process. In this study we investigate the first of these hypotheses, that source heterogeneity explains global Fe-Mg isotope systematics. We compile a global dataset of oceanic basalt Fe and Mg isotopes and complement this with new Fe-Mg isotope data from locations possessing some of the most extreme radiogenic isotope ratios for their setting: ocean island basalts from the Cook-Austral and Society islands and a Mid-Atlantic Ridge basalt. Despite both Fe and Mg isotope systems having the ability to trace recycled crustal material in the mantle, their global systematics are very different in this dataset. The global compilation of primitive oceanic basalts records heavier Fe (higher δ57Fe) isotope compositions than bulk silicate earth (BSE), but a mixture of heavier and lighter Mg isotope compositions than BSE. By employing a coupled Fe-Mg equilibrium isotope fractionation model during mantle melting we show that much of this isotopic variability can be generated by the mixed melts produced by melting of peridotite mantle containing moderate amounts of recycled crust as a discrete lithology. The Fe isotope composition of the melts is controlled by the bulk isotope composition of the recycled crust (expected to be considerably heavier than BSE, but variable). In contrast, the Mg isotope composition is controlled by source mineralogy. Olivine-poor lithologies such as recycled crust are able to generate large Mg isotope fractionations during melting, both positive and negative (± 0.1‰) relative to the mantle source, depending on the presence of spinel, clinopyroxene or garnet. These melt Mg isotope fractionations are consistent with the Mg isotope compositions of mid-ocean ridge basalts generated by variable depths of mantle melting. Our equilibrium model provides a baseline to test hypotheses of Fe-Mg isotope variability in basalts: our results show that contributions from recycled crust-derived melts, generated in spinel-, pyroxene-, and garnet-bearing mineral assemblages in the mantle, would be able to produce much of the Fe-Mg isotope variability seen in the global compilation of primitive oceanic basalts, without requiring isotopically extreme mantle components (e.g., carbonate with a light Mg isotope signature) or disequilibrium fractionation. However some basalt variability in ocean island settings may indeed fall outside the paradigm of pyroxenite heterogeneity – whilst we consider carbonates unlikely to be important, disequilibrium processes may in these cases play a role.
•Most oceanic basalt δ57Fe–δ26Mg is consistent with small pyroxenite contributions.•Basalt δ57Fe–δ26Mg constrain mantle composition and lithology respectively.•MORB δ26Mg forms a coherent global array with ridge depth.•Some basalt δ57Fe–δ26Mg are not matched by pyroxenite & equilibrium fractionation.
•Saffron as a high value spice is prone to mislabeling of origin.•Stable isotopes and bioelements are used to discriminate Iranian and Chinese saffron.•Chemometric models show good country and ...regional discrimination of saffron.
Origin verification of high-value saffron is essential for fair trade and to protect consumers' interests and rights. A traceability method using elemental content (% C and % N) and stable isotopes (δ13C, δ2H, δ18O, and δ15N) combined with chemometrics was developed to discriminate saffron from Iran and China and classify major domestic production areas in China. Results showed that Iranian samples had lower % C and % N contents but higher δ13C values than Chinese origin saffron, with δ13C acting as an important variable for origin discrimination. Moreover, δ2H and δ13C isotopes were found to be important variables to classify Chinese regional saffron origin. Two supervised pattern recognition models (PLS-DA) developed to classify Iranian and Chinese saffron, and regional Chinese saffron had a discrimination accuracy of 85.0 % and 80.2 %, respectively. These models provide the basis for a new regulatory inspection procedure to verify saffron origin and label claims, minimizing fraudulent mislabeling and adding value to saffron from specific regions.
Aquatic and terrestrial ecosystems are connected through reciprocal fluxes of energy and nutrients that can subsidize consumers. Past research on reciprocal aquatic–terrestrial subsidies to consumers ...has generally focused on subsidy quantity while ignoring major differences in the nutritional composition of aquatic and terrestrial resources. Because aquatic resources contain substantially more highly unsaturated omega‐3 fatty acids (HUFAs) than terrestrial resources, aquatic subsidies may play a unique role by supplying these critical compounds to both aquatic and terrestrial consumers.
Here, we first characterized nutritional quality in terms of HUFA content in aquatic and terrestrial insect prey. We then used bulk stable isotope analyses to estimate subsidy use by stream and riparian consumers coupled with compound‐specific stable isotope analyses, which allowed us to document consumer HUFA sources. Finally, in order to understand the nutritional importance of aquatic‐derived HUFAs for riparian consumers, we conducted manipulative diet experiments on Eastern Phoebe (Sayornis phoebe) chicks in the laboratory.
Aquatic insects were significantly enriched in HUFAs, mainly in terms of eicosapentaenoic acid (EPA), compared with terrestrial insects. Stream fishes relied mainly upon aquatic resources, while insectivorous birds varied in their use of aquatic subsidies across sites. However, like stream fishes, Eastern Phoebe chicks received HUFAs from aquatic insects, even when they were heavily reliant upon terrestrial insects for their overall diet. In the laboratory, dietary HUFAs, such as those supplied by aquatic insects, increased the growth rate and condition of Eastern Phoebe chicks.
This study demonstrates that aquatic and terrestrial subsidies are not nutritionally reciprocal from the perspective of consumers because aquatic resources are the main source of critical fatty acids for both stream and riparian consumers. It also confirms previous findings on the nutritional importance of HUFAs for riparian birds, demonstrating that an insectivorous riparian lifestyle influences avian nutritional needs. Finally, our findings raise the possibility that birds and other riparian insectivores may experience nutritional mismatches with terrestrial prey if they do not have access to high‐quality aquatic subsidies as a consequence of aquatic habitat degradation or shifts in consumer and resource phenology.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Poultry are farmed globally, with chicken (Gallus gallus domesticus) being the leading domesticated species. Although domestic chicken bones have been reported from some Early Holocene sites, their ...origin is controversial and there is no reliable domestic chicken bone older than the Middle Holocene. Here, we studied goose bones from Tianluoshan—a 7,000-y-old rice cultivation village in the lower Yangtze River valley, China—using histological, geochemical, biochemical, and morphological approaches. Histological analysis revealed that one of the bones was derived from a locally bred chick, although no wild goose species breed in southern China. The analysis of oxygen-stable isotope composition supported this observation and further revealed that some of the mature bones were also derived from locally bred individuals. The nitrogen-stable isotope composition showed that locally bred mature birds fed on foods different from those eaten by migrant individuals. Morphological analysis revealed that the locally bred mature birds were homogenous in size, whereas radiocarbon dating clearly demonstrated that the samples from locally bred individuals were ∼7,000 y old. The histological, geochemical, biochemical, morphological, and contextual evidence suggest that geese at Tianluoshan village were at an early stage of domestication. The goose population appears to have been maintained for several generations without the introduction of individuals from other populations and may have been fed cultivated paddy rice. These findings indicate that goose domestication dates back 7,000 y, making geese the oldest domesticated poultry species in history.
This study identified the occurrence of Holocene chronology hiatuses in the sedimentary record of the Patos-Mirim system caused by river avulsion processes, as well as evidence of sharp anthropogenic ...changes in the surrounding region of the lagoon water bodies. The presence of chronology hiatuses demonstrates the importance of considering the disturbance effect of paleo-drainage processes on the paleoenvironmental resolution and expression of the sedimentary record of such coastal plains. Anthropogenic activities especially those related to agriculture and forestry have increased significantly during the great acceleration, resulting in modifications of both the landscape and the environmental conditions of the lagoon bodies. Such impacts were clearly reflected in the sedimentary record where abrupt changes in palynological trends, sedimentary DNA, isotopic and granulometric analyses were inferred. The climatic conditions combined with regressive sea level can explain the chronology hiatuses. Pollen analyses demonstrated changes in the landscape, particularly indicated by the shift from Cyperaceae to Poaceae dominance after the 1960 CE. Therefore, all proxies together demonstrate the modification in the landscape and changes in the environment, clearly influenced by anthropogenic action from unsustainable agricultural practices.
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•The Patos-Mirim system is extensively dissected by Pleistocene/Holocene incised valleys.•The Holocene record is eroded by currents of meandering streams, which expression consisted of a Middle Holocene hiatus.•Novel palynological and 16S rRNA long-term data demonstrate changes in both landscape and lagoon anthropogenic transformation.
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