Diet shift of upland buzzards (Buteo hemilasius): evidence from stable carbon isotope ratios

We measured the stable carbon isotope ratios for muscle of the upland buzzards (Buteo hemilasius), plateau pika (Ochotoma curzoniae), root vole (Microtus oeconomus), plateau zokor (Myospalax fontanierii) and passerine bird species at the Haibei Alpine Meadow Ecosystem Research Station (HAMERS), and provided diet information of upland buzzards with the measurement of stable carbon isotopes in tissues of these consumers. The results showed that δ~(13)C values of small mammals and passerine bird species ranged from -25.57‰ to -25.78‰ (n = 12), and from -24.81‰ to -22.51% (n = 43), respectively, δ~(13)C values of the upland buzzards ranged from -22.60‰ to -23.10‰ when food was not available. The difference in δ~(13)C values (2.88‰±0.31‰) between upland buzzards and small mammals was much larger than the differences reported previously, 1‰-2‰, and showed significant difference, while 1.31‰±0.34‰ between upland buzzard and passerine bird species did not differ from the previously reported trophic fractionation difference of 1‰-2‰. Estimation of trophic position indicated that upland buzzards stand at trophic position 4.23, far from that of small mammals, i.e., upland buzzards scarcely captured small mammals as food at the duration of food shortage. According to isotope mass balance model, small mammals contributed 7.89% to 35.04% of carbon to the food source of the upland buzzards, while passerine bird species contributed 64.96% to 92.11%. Upland buzzards turned to passerine bird species as food during times of shortage of small mammals. δ~(13)C value, a useful indicator of diet, indicates that the upland buzzards feed mainly on passerine bird species rather than small mammals due to "you are what you eat" when small mammal preys are becoming scarce.

Characterization of photosynthetic pathway of plant species growing in the eastern Tibetan plateau using stable carbon isotope composition

The photosynthetic pathway of plant species collected at Menyuan, Henan, and Maduo sites, east of Tibetan Plateau, China, during the growing season were studied using stable carbon isotopes in leaves. The 232 samples leaves analyzed belonged to 161 species, 30 families, and 94 genera. The delta(13)C values (from -24.6 to -29.2 %o) indicated that all the considered species had a photosynthetic C-3 pathway. The absence of plant species with C-4 photosynthetic pathway might be due to the extremely low air temperature characterizing the Tibetan Plateau. The average delta(13)C value was significantly (p < 0.05) different between annuals and perennials at the three considered study sites. Hence the longer-lived species had greater water-use efficiency (WUE) than shorter-lived species, that is, longer-lived species are better adapted to the extreme environmental conditions of the Tibetan Plateau.

Stable carbon and oxygen isotope composition of benthic foraminifera

Seventeen surface sediment samples from the North Atlantic Ocean off NE-Greenland between 76° and 81°N, and nine samples from the South Atlantic Ocean close to Bouvet Island between 48° and 55°S were taken with the aid of a Multiple Corer and investigated for their live (Rose Bengal stained) benthic foraminiferal content within the upper 15 cm of sediment. Preferentially endobenthic Melonis barleeanum, Melonis zaandami, and Bulimina aculeata as well as preferentially epibenthic Lobatula lobatula were counted from 1-cm-thick sediment slices each and analyzed for stable carbon and oxygen isotopic compositions of their calcareous tests. Live and dead specimens were counted and measured separately. The carbon isotopic composition of the foraminifera was compared to that of the dissolved inorganic carbon (DIC) of simultaneously sampled bottom water. During a period of one month, one station off NE-Greenland was replicately sampled once every week and samples were processed as above. Live specimens of Lobatula lobatula are confined to the uppermost two centimeters of sediment. Live specimens of Melonis spp. are found down to 8 cm within the sediment but with a distinct sub-surface maximum between 2 and 5 cm. The down-core distribution of live Bulimina aculeata shows a distinct surface maximum in the top centimeter and constant but low numbers down to 11-cm subbottom depth. The average stable carbon isotopic composition (d13C versus per mil PDB) of live Lobatula lobatula off NE-Greenland is by 0.4±0.1 per mil higher than the d13CDIC of the ambient bottom water at the time of sampling. There is evidence that this species calcify before the ice-free season, when bottom water d13CDIC is supposed to be higher. This would reconfirm the one-to-one relationship between d13C of ambient water DIC and cibicids, widely used by paleoceanographers. Live Melonis barleeanum show a negative offset from bottom water DIC of -1.7±0.6 per mil in the uppermost sediment and of -2.2±0.5 per mil in 3-4-cm subbottom depth. All d13C values of live Melonis spp. decrease within the upper four centimeters, regardless of the time of sampling and site investigated. The offset of live Bulimina aculeata from bottom water d13CDIC values of 8 stations rather constantly amounts to -0.6±0.1 per mil, no matter what subbottom depth the specimens are from. At one station however, where is strong indication of elevated organic carbon flux, the negative offset averaged over all sub-bottom depths increases to -1.5±0.2 per mil. Buliminids actively move within the sediment and by this either record an average isotope signal of the pore water or the signal of one specific calcification depth. The recorded signal, however, depends on the organic carbon flux and reflects general but site-specific pore water d13CDIC values. If compared with epibenthic d13C values from the same site, not influenced by pore water and related phytodetritus layer effects, Buliminad13C values bear some potential as a paleoproductivity proxy. Specimens of Melonis spp. seem to prefer a more static way of life and calcify at different but individually fix depths within the sediment. Although live specimens thus record a stratified pore water d13C signal, there is no means yet to correct for bioturbational and early diagenetic effects in fossil faunas.

An integrated study (geochemistry, stable oxygen and carbon isotopes, nannofossils, planktonic foraminifera, inoceramid bivalves, ammonites and crinoids) of the Waxahachie Dam Spillway section, north Texas: a possible boundary stratotype for the base of the Campanian Stage

The spillway of Lake Waxahachie, Ellis County (Texas), exposes a > 17 m section of the Hutchins Member of the Austin Chalk Group, un-conformably overlain by Taylor Clay. The Austin sequence was regarded as a potential Global Stratotype Section for the base of the Campanian Stage at the 1995 Brussels meeting on Cretaceous Stage boundaries, with the last occurrence of the crinoid Marsupites testudinarius (von Schlotheim, 1820) as the potential boundary marker. An integrated study of the geochemistry, stable carbon and oxgen isotopes, nannofossils, planktonic foraminifera, inoceramid bivalves, ammonites and crinoids of this section place the last occurrence of M. testudinarius in a matrix of eighteen ancillary biostratigraphic markers, while the boundary can also be recognised on the basis of a delta C-13 excursion that can, in principle, be detected globally in marine sediments. A new forma of the crinoid Marsupites testudinarius is introduced. The Waxahachie section fulfils sufficient geological criteria as to be an excellent candidate GSSP for the base of the Campanian Stage, if problems of ownership and access to the section can be resolved.

Iron Age Pastoral Nomadism and Agriculture in the Eastern Eurasian Steppe: Implications from Dental Palaeopathology and Stable Carbon and Nitrogen Isotopes

Iron Age societies of the eastern Eurasian steppe are traditionally viewed as nomadic pastoralists. However, recent archaeological and anthropological research in Kazakhstan has reminded us that pastoralist economies can be highly complex and involve agriculture. This paper explores the nature of the pastoralist economies in two Early Iron Age populations from the burial grounds of Ai-Dai and Aymyrlyg in Southern Siberia. These populations represent two cultural groups of the Scythian World - the Tagar Culture of the Minusinsk Basin and the Uyuk Culture of Tuva. Analysis of dental palaeopathology and carbon and nitrogen stable isotopes suggests that domesticated cereals, particularly millet, and fish formed a major component of the diet of both groups. The findings contribute to the emerging picture of the nuances of Early Iron Age subsistence strategies on the eastern steppe.

Stable carbon (delta(13)C) and nitrogen (delta(15)N) isotopes as natural indicators of live and dry food in Piaractus mesopotamicus (Holmberg, 1887) larval tissue

This study proposed the use of the stable isotope technique to track the type of food utilized by pacu Piaractus mesopotamicus larvae during their development, and to identify the moment when the larvae start using nutrients from the dry diet by retaining its carbon and nitrogen atoms in their body tissues. Five-day-old pacu larvae at the onset of exogenous feeding were fed Artemia nauplii or formulated diet exclusively; nauplii+formulated diet during the entire period; or were weaned from nauplii to a dry diet after 3, 6 or 12 days after the first feeding. delta(13)C and delta(15)N values for Artemia nauplii were -15.1 parts per thousand and 4.7 parts per thousand, respectively, and -25.0 parts per thousand and 7.4 parts per thousand for the dry diet. The initial isotopic composition of the larval tissue was -20.2 parts per thousand and 9.5 parts per thousand for delta(13)C and delta(15)N respectively. Later, at the end of a 42-day feeding period, larvae fed Artemia nauplii alone reached values of -12.7 parts per thousand and 7.0 parts per thousand for delta(13)C and delta(15)N respectively. Larvae that received the formulated diet alone showed values of -22.7 parts per thousand for delta(13)C and 9.6 parts per thousand for delta(15)N. The stable isotope technique was precise, and the time at which the larvae utilized Artemia nauplii, and later dry diet as a food source could be clearly defined.

PALEOCLIMATIC CONTROLS ON STABLE OXYGEN AND CARBON ISOTOPES IN CALICHE OF THE ABO FORMATION (PERMIAN), SOUTH-CENTRAL NEW-MEXICO, USA

The stable oxygen and carbon isotopic composition of caliche in fluvial and supratidal rocks of the Abo Formation (Permian), south-central New Mexico, is controlled by palecoclimate and depositional environment. Fluvial caliche consists of low-Mg calcite nodules and vertically oriented tubules that display stage II texture. Micrite matrix support, brecciation, ooids/pisoliths, aveolar-septal texture, and peloids are common in the fluvial caliche and, along with red color and slickensides in the host shale, indicate pedogenesis in a well-oxidized vadose zone. In contrast, periodic waterlogging of the supratidal paleosols, probably due to high water table, is indicated by drab colors, carbonaceous flecks, horizontal rhizoliths, and the paucity of vadose textures in the stage II caliche nodules.Stable oxygen isotopes are similar in the fluvial and supratidal caliches and range from 21.6 to 30.5 parts per thousand (SMOW). The data exhibit a crude bimodality and delta-O-18 enrichment with a decrease in age (higher in the section). Consideration of these data in the context of delta-temperature relations suggests that 1) surface waters responsible for caliche formation increased in delta-O-18 (from roughly -8 to + 1 parts per thousand) over the 18 m.y. time interval that separated the lowest stratigraphic nodule horizon from the highest, 2) the increasing delta-O-18 values also reflect a warming trend (approximately 15-degrees to nearly 30-degrees-C) in the mean monthly temperature over this same time period, with perhaps an associated increase in Permian ocean temperatures, and 3) the significant variation in delta-O-18 from oldest to youngest caliche was probably enhanced by the amount effect, such that as the temperature increased, the amount of precipitation decreased, resulting in high delta-O-18 values.Caliches in the Abo are enriched in heavy carbon (-7.2 to -1.5 part per thousand PDB) compared to that of soil carbonate derived exclusively from C3 plants (-12 part per thousand PDB), and the supratidal caliches contain somewhat heavier carbon compared to the fluvial caliche. The delta-C-13 values for both environments increase with a decrease in caliche age. These results indicate that as the temperature increased and rainfall decreased with time, the level of C3 plant productivity apparently declined, allowing a greater influx of atmospheric CO2 into the soil. This can only occur when soil respiration rates are quite low or at very shallow depths (less than 10 cm), or both. Atmospheric CO2 seems to have invaded the supratidal soils to a somewhat greater extent than the fluvial soils.

Poultry offal meal traceability in meat quail tissues using the technique of stable carbon (13C/12C) and nitrogen (15N/14N) isotopes

Studies on the detection of animal by-products in poultry meat are rare, and non-existent on quail meat. This study aimed at detectiong increasing levels of poultry offal meal (POM) in quail meat, using carbon (13C/12C) and nitrogen (15N/14N) stable isotopes technique. Sixty four on-day-old male quails derived from a commercial farm were randomly distributed into seven different groups, which were fed experimental diets containing 0, 1.5, 3.0, 4.5, 6.0, 7.5, and 15% of POM. Diets were formulated to contain equal energy, protein, and amino acid levels. Four individuals per treatment were sacrificed at 42 days of age for breast muscle (Pectoralis major), keel, and tibia collection, which were subsequently submitted to analyses. Isotopic δ13C and δ15N enrichment was observed in all analyzed tissues, with the lowest detection level of 3% dietary inclusion of poultry offal meal.

Simultaneous Determination of Stable Carbon, Oxygen, and Hydrogen Isotopes in Cellulose

A technological development is described through which the stable carbon-, oxygen-, and nonexchangeable hydrogen-isotopic ratios (δ13C,δ18O,δ2H) are determined on a single carbohydrate (cellulose) sample with precision equivalent to conventional techniques (δ13 C 0.15‰,δ18O 0.30‰,δ2H 3.0‰). This triple-isotope approach offers significant new research opportunities, most notably in physiology and medicine, isotope biogeochem- istry, forensic science, and palaeoclimatology, when isotopic analysis of a common sample is desirable or when sample material is limited.

Bryozoan stable carbon and hydrogen isotopes: relationships between the isotopic composition of zooids, statoblasts and lake water

We explored the extent to which δ13C and δD values of freshwater bryozoan statoblasts can provide information about the isotopic composition of zooids, bryozoan food and surrounding water. Bryozoan samples were collected from 23 sites and encompassed ranges of nearly 30‰ for δ13C and 100‰ for δD values. δ13C offsets between zooids and statoblasts generally ranged from −3 to +4.5‰, with larger offsets observed in four samples. However, a laboratory study with Plumatella emarginata and Lophopus crystallinus demonstrated that, in controlled settings, zooids had only 0–1.2‰ higher δ13C values than statoblasts, and 1.7‰ higher values than their food. At our field sites, we observed a strong positive correlation between median δ13C values of zooids and median δ13C values of corresponding statoblasts. We also observed a positive correlation between median δD values of zooids and statoblasts for Plumatella, and a positive correlation between median δD values of statoblasts and δD values of lake water for Plumatella and when all bryozoan taxa were examined together. Our results suggest that isotope measurements on statoblasts collected from flotsam or sediment samples can provide information on the feeding ecology of bryozoans and the H isotopic composition of lake water.

Stable carbon and oxygen isotopes in tree rings show physiological responses of Pericopsis elata to precipitation in the Congo Basin

In equatorial regions, where tree rings are less distinct or even absent, the response of forests to high-frequency climate variability is poorly understood. We measured stable carbon and oxygen isotopes in anatomically distinct, annual growth rings of four Pericopsis elata trees from a plantation in the Congo Basin, to assess their sensitivity to recorded changes in precipitation over the last 50 y. Our results suggest that oxygen isotopes have high common signal strength (EPS = 0.74), and respond to multi-annual precipitation variability at the regional scale, with low δ18O values (28–29‰) during wetter conditions (1960–1970). Conversely, δ13C are mostly related to growth variation, which in a light-demanding species are driven by competition for light. Differences in δ13C values between fast- and slow-growing trees (c. 2‰), result in low common signal strength (EPS = 0.37) and are driven by micro-site conditions rather than by climate. This study highlights the potential for understanding the causes of growth variation in P. elata as well as past hydroclimatic changes, in a climatically complex region characterized by a bimodal distribution in precipitation.