共查询到20条相似文献,搜索用时 31 毫秒
1.
Stable isotopes of nitrogen (δ15 N) and carbon (δ13 C) were measured for Atlantic salmon Salmo salar and their intestinal cestode, Eubothrium crassum , sharing the same diet. Atlantic salmon muscle tissues were enriched in 15 N and depleted in 13 C compared to their prey (sprat Sprattus sprattus sprattus ) and their intestinal cestode. There was no significant difference in δ15 N or δ13 C between E. crassum and the sprat. Differences in nutrient uptake and intestine physiology between Atlantic salmon and E. crassum are discussed, as well as how these may give rise to different fractionations of stable isotopes between a host and its parasites. Furthermore, Atlantic salmon contained a significantly higher lipid content than their prey, which may partly explain differences in δ13 C values between the host and its cestode. In addition, cestodes inhabiting lipid-rich hosts were also lipid rich. Larger Atlantic salmon were enriched in 15 N compared to smaller fish. Cestodes inhabiting large hosts were also enriched in 15 N compared to parasites living in smaller hosts. The last two results were explained by larger fish possibly feeding from a higher trophic level, or from larger and older prey, that resulted in both a higher lipid content and an enrichment in 15 N. 相似文献
2.
1. Changes of δ13 C and its relation to leaf development, biochemical content and water stress were monitored over a 2 year period in two co-occurring Mediterranean oak species: the deciduous Quercus pubescens and the evergreen Quercus ilex .
2. The time course of leaf δ13 C showed different patterns in the two species. Young Q. pubescens leaves had a high δ13 C and a marked decrease occurred during leaf growth. In contrast, leaves at budburst and maturity did not differ significantly in the case of Q. ilex . We suggest that the difference between δ13 C of young leaves was linked to differential use of reserves of carbon compounds in the two species.
3. δ13 C values of mature leaves were negatively correlated with minimum seasonal values of predawn water potential, suggesting that a functional adjustment to water resources occurred.
4. There was a significant correlation between individual δ13 C values for two successive years. This interannual dependence showed that δ13 C rankings between trees were constant through time. 相似文献
2. The time course of leaf δ
3. δ
4. There was a significant correlation between individual δ
3.
This study investigated the impact of lipid extraction, CaCO3 removal and of both treatments combined on fish tissue δ13 C, δ15 N and C:N ratio. Furthermore, the suitability of empirical δ13 C lipid normalization and correction models was examined. δ15 N was affected by lipid extraction (increase of up to 1·65‰) and by the combination of both treatments, while acidification alone showed no effect. The observed shift in δ15 N represents a significant bias in trophic level estimates, i.e. lipid-extracted samples are not suitable for δ15 N analysis. C:N and δ13 C were significantly affected by lipid extraction, proportional to initial tissue lipid content. For both variables, rates of change with lipid content (ΔC:N and Δδ13 C) were species specific. All tested lipid normalization and correction models produced biased estimates of fish tissue δ13 C, probably due to a non-representative database and incorrect assumptions and generalizations the models were based on. Improved models need a priori more extensive and detailed studies of the relationships between lipid content, C:N and δ13 C, as well as of the underlying biochemical processes. 相似文献
4.
The scales of whitefish Coregonus lavaretus were used in place of dorsal muscle, which necessitates killing the fish, to study food webs from the δ13 C and δ15 N isotopic ratios in the organic fraction. As scales are composed of both organic and calcified fractions, a protocol for scale decalcification was first devised. The δ13 C and δ15 N values of the decalcified scales were then shown to be closely correlated to those of the dorsal muscle, demonstrating that scales could be used in place of muscle to study food webs. Changes in the δ13 C of whitefish were determined from a scale collection that extended over the period during which the trophic state of Lake Geneva was recovering. 相似文献
5.
Seasonal Variation of δ^13C of Four Tree Species: A Biological Integrator of Environmental Variables 总被引:2,自引:0,他引:2
Hai-Tao LI Jun XIA Le XIANG Tao LIANG Qi-Jing LIU 《植物学报(英文版)》2005,47(12):1459-1469
Foliar δ^13C values, an indicator of long-term intercellular carbon dioxide concentration and, thus, of long-term water use efficiency (WUE) in plants, were measured for Pinus massoniana Lamb., P. elliottii Engelm., Cunninghamia laceolata (Lamb.) Hook., and Schima superba Gardn. et Champ. in a restored forest ecosystem in the Jiazhu River Basin. Seasonal variation and the relationship between the foliar δ^13C values of the four species and environmental factors (monthly total precipitation, monthly average air temperature, relative humidity, atmospheric pressure, and monthly total solar radiation and evaporation) were investigated. The monthly δ^13C values and WUE of the four species increased with increasing precipitation, air temperature, solar radiation, and evaporation, whereas δ^13C values of the four species decreased with increasing relative humidity and atmospheric pressure. Despite significant differences in δ^13C seasonal means for the four species, our results demonstrate a significant convergence in the responses of δ^13C values and WUE to seasonal variations in environmental factors among the species investigated and that the δ^13C signature for each species gives a strong indication of environmental variables. 相似文献
6.
R. L. FRANCE 《Freshwater Biology》1996,36(1):1-6
1. Although marine research has indicated that metabolic fractionations of 13 C due to differences in organismal trophic position and proximal composition can complicate the isotopic interpretation of energy flow pathways, such potentially confounding problems have never been examined in freshwater benthic food webs.
2. The δ13 C values of animals comprising a littoral benthic food web composited from four Canadian Shield lakes showed no relationship with either individual trophic position (δ15 N) or lipid content (C/N ratios).
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ13 C and δ15 N values, thereby masking any possibility of observing 13 C trophic enrichment.
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ13 C for freshwater benthic organisms in order to accommodate trophic fractionations which are presumed to occur, based on data from marine offshore food webs, may also be inappropriate. 相似文献
2. The δ
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ
7.
Patterns of stable isotope signatures in willow warbler Phylloscopus trochilus feathers collected in Africa 总被引:2,自引:0,他引:2
We conducted stable isotope analyses of nitrogen and carbon on feathers obtained from willow warblers in Africa to find an explanation for a previously observed pattern of different δ15 N and δ13 C values across a migratory divide in central Scandinavia. A new data set confirms that north Scandinavian birds of the subspecies P. t. acredula have higher δ15 N values than south Scandinavian birds of the subspecies P. t. trochilus . In Africa, we found significant differences for both δ15 N and δ13 C values among feathers collected from major geographical regions as well as between countries within regions. Isotope signatures of δ15 N and δ13 C in Scandinavian acredula matched well with those of willow warblers sampled in southern parts of Africa, but differed from samples obtained in East and West Africa. Isotope signatures in Scandinavian trochilus did not agree with the pattern in any of the three African regions (West, East or South). However, a more detailed analysis of the isotopic data in feathers from countries within West Africa, which is the wintering region of Swedish trochilus based on ringing recoveries, revealed a correspondence with samples from Liberia, the Ivory Coast and Nigeria. 相似文献
8.
The influence of different feeding levels below and slightly above maintenance on whole body δ13 C and δ15 N values of Nile tilapia Oreochromis niloticus was examined. The energy budget of each fish was determined by indirect calorimetry. The δ13 C values of the lipid-free material of Nile tilapia fed below and slightly above maintenance level did not differ between the feeding groups, but the δ13 C values in the lipids and the δ15 N values of the lipid-free material showed small but significant differences. Those fish with a negative lipid retention had significantly higher δ13 C values in the lipid fraction compared to fish that synthesized fatty acids. There was a significant negative correlation between the amount of energy metabolized by the fish and both the δ13 C values in the lipids and the δ15 N values of the lipid-free material. Fasting and feeding below the maintenance level may influence the isotopic composition of animals and should therefore be considered in ecological and nutritional studies. 相似文献
9.
1. Growth, density and δ13 C of wood and leaf area were measured in two adjacent stands of 6 year-old Eucalyptus globulus growing in the 600–700 mm year–1 rainfall region of south-western Australia. Study sites were identical except for differences in the availability of water owing to physical properties of soil profiles and location of sites within the landscape.
2. Abundance of13 C (expressed as δ13 C) in wood of trees growing on the drought-prone site (– 24·8‰±1·4) was greater than in other trees (– 25·8‰±1·2, P <0·001) throughout the 6 years and, with further development, the δ13 C signatures of wood may become useful indices of drought-susceptibility in plantations within a few years of establishment. The seasonal pattern of δ13 C of wood appeared to reflect seasonal variation in water availability and duration of cambial activity.
3. Basic density of wood of trees growing on the more drought-prone site (496±14·0 kg m–3 ) was reduced compared to other trees (554±5·3 kg m–3 , P <0·001). δ13 C of wood across boundaries of growth-rings suggested that drought stopped cambial activity resulting in less production of late wood and less dense wood.
4. The stand growing on the drought-prone site had reduced growth, wood yield and leaf area but identical specific leaf area. Annual growth was correlated with the previous season's rainfall. Together, these results suggested that within the same evaporative climate, drought reduces growth primarily by reducing leaf area and that there is a lag between onset of drought and reduced productivity. 相似文献
2. Abundance of
3. Basic density of wood of trees growing on the more drought-prone site (496±14·0 kg m
4. The stand growing on the drought-prone site had reduced growth, wood yield and leaf area but identical specific leaf area. Annual growth was correlated with the previous season's rainfall. Together, these results suggested that within the same evaporative climate, drought reduces growth primarily by reducing leaf area and that there is a lag between onset of drought and reduced productivity. 相似文献
10.
Assessing the reproductive contributions of sympatric anadromous and freshwater‐resident brook trout
R. A. Curry† 《Journal of fish biology》2005,66(3):741-757
The δ13 C, δ15 N and δ34 S isotope values of newly emerged, brook trout Salvelinus fontinalis alevins (free‐swimming individuals beginning exogenous feeding) were examined to determine if progeny of anadromous female spawners could be detected and their contributions to reproduction assessed in river systems with mixed migration strategies. Separation of anadromous and freshwater resident and immigrant sources of progeny could be detected primarily using δ13 C values before alevins reached a size of 28 mm fork length and c . 20 days after exogenous feeding began. Among 10 populations, the contributions of anadromous females ranged from 0 to 42% of newly emerged alevins. Correlations between anadromous contributions and estimates of total brook trout density and alevin production were unexpectedly negative. 相似文献
11.
Stable isotopes of carbon and nitrogen as indicators of diet and trophic structure of the fish community in a shallow hypereutrophic lake 总被引:5,自引:1,他引:4
Stable carbon (δ13 C) and nitrogen (δ15 N) isotopes were employed to elucidate energy flows and trophic interactions in Lake Apopka, a hypereutrophic lake in central Florida, U.S.A. Isotope compositions of lake biota ranged from −27·1 to −3·0‰ for δ13 C, and from 3·7 to 13·9‰ for δ15 N. The food web was based primarily on plankton production with diatoms, Microcystis and zooplankton dominating the diet of fish. Carbon isotope evidence showed that pico- and nano-phytoplankton were not a direct carbon source for fish, but were important to zooplankton. δ15 N mass balance estimates indicated that planktivorous fish obtained 48–85% of their diets from zooplankton. The ∼3‰ range of δ15 N in gizzard shad reflected increasing dependence on zooplankton as fish grew whereas the positive relationship between total length and δ15 N of largemouth bass reflected increasing predation on larger planktivorous fish with growth. The broad ranges of δ13 C (−25·9 to −9·5‰) and δ15 N (5·8 to 14·4‰) of blue tilapia were indicators of diet diversity. Two presumed omnivores (brown bullhead and white catfish) and piscivores (black crappie, largemouth bass and Florida gar) were found to depend on planktivorous fish. However, stable isotope data revealed no trophic links between blue tilapia, an abundant fish in the near-shore area, and piscivores. 相似文献
12.
Abstract. In the marine environment, the range of values of carbon isotope fractionation between particulate tissue of phytoplankton and inorganic carbon can be more than 20‰ (− 35‰ < δ13 C < − 14‰). This review considers the influence of seawater temperature, lipid content of phytoplanktonic cells, kinetic fractionation, and carbon pathway on δ13 C values observed at sea.
In order to study the contribution of carboxylases (RUBISCO and the β-carboxylases phosphoenolpyruvate carboxylase, phosphoenoplpyruvate carboxykinase and pyruvate carboxylase) to variations of particulate δ13 C values at sea, we present results obtained simultenously on carboxylase activities and δ13 C in various environmental conditions. The lowest δ13 C values are clearly associated with predominance of ribulose-1.5-bisphosphate carboxylase activity, but it was more difficult to explain the high δ13 C values. Different hypotheses are discussed. 相似文献
In order to study the contribution of carboxylases (RUBISCO and the β-carboxylases phosphoenolpyruvate carboxylase, phosphoenoplpyruvate carboxykinase and pyruvate carboxylase) to variations of particulate δ
13.
1. Increased water motion is expected to reduce boundary layer diffusion resistance of autotrophs, thereby enabling greater isotopic discrimination against 13 C such that lower δ13 C values (ratio of 13 C : 12 C) should ensue. A field test of this hypothesis was undertaken by sampling benthic algae in streams of differing current speed.
2. Contrary to the expected negative relationship between δ13 C and water motion, filamentous benthic algae were found to exhibit higher δ13 C values in rapid water.
3. Under conditions of low current in the streams studied, concentrations of dissolved organic carbon as measured by water colour are elevated through the microbial decomposition of largely terrestrial organic matter. Photoassimilation of this respired carbon by benthic filamentous algae generates13 C‐depletion and lower δ13 C values, and appears to be substantial enough in the streams used in the present study to override the competing influence of water motion on boundary layer thickness. 相似文献
2. Contrary to the expected negative relationship between δ
3. Under conditions of low current in the streams studied, concentrations of dissolved organic carbon as measured by water colour are elevated through the microbial decomposition of largely terrestrial organic matter. Photoassimilation of this respired carbon by benthic filamentous algae generates
14.
We evaluated diurnal and seasonal patterns of carbon isotope composition of leaf dark-respired CO2 ( δ 13 Cl ) in the C3 perennial shrub velvet mesquite ( Prosopis velutina ) across flood plain and upland savanna ecosystems in the south-western USA. δ 13 Cl of darkened leaves increased to maximum values late during daytime periods and declined gradually over night-time periods to minimum values at pre-dawn. The magnitude of the diurnal shift in δ 13 Cl was strongly influenced by seasonal and habitat-related differences in soil water availability and leaf surface vapour pressure deficit. δ 13 Cl and the cumulative flux-weighted δ 13 C value of photosynthates were positively correlated, suggesting that progressive 13 C enrichment of the CO2 evolved by darkened leaves during the daytime mainly resulted from short-term changes in photosynthetic 13 C discrimination and associated shifts in the δ 13 C signature of primary respiratory substrates. The 13 C enrichment of dark-respired CO2 relative to photosynthates across habitats and seasons was 4 to 6‰ at the end of the daytime period (1800 h), but progressively declined to 0‰ by pre-dawn (0300 h). The origin of night-time and daytime variations in δ 13 Cl is discussed in terms of the carbon source(s) feeding respiration and the drought-induced changes in carbon metabolism. 相似文献
15.
1. Although marine research has indicated that metabolic fractionations of 13 C due to differences in organismal trophic position and proximal composition can complicate the isotopic interpretation of energy flow pathways, such potentially confounding problems have never been examined in freshwater benthic food webs.
2. The δ13 C values of animals comprising a littoral benthic food web composited from four Canadian Shield lakes showed no relationship with either individual trophic position (δ15 N) or lipid content (C/N ratios).
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ13 C and δ15 N values, thereby masking any possibility of observing 13 C trophic enrichment.
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ13 C for freshwater benthic organisms in order to accommodate trophic fractionations which are presumed to occur, based on data from marine offshore food webs, may also be inappropriate. 相似文献
2. The δ
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ
16.
Elevated pyruvate,orthophosphate dikinase (PPDK) activity alters carbon metabolism in C3 transgenic potatoes with a C4 maize PPDK gene 总被引:1,自引:0,他引:1
Ken Ishimaru Yasunobu Ohkawa Teruo Ishige Dennis J. Tobias Ryu Ohsugi 《Physiologia plantarum》1998,103(3):340-346
Changes in carbon metabolism and δ13 C value of transgenic potato plants with a maize pyruvate,orthophosphate dikinase (PPDK; EC 2.7.9.1) gene are reported. PPDK catalyzes the formation of phospho enol pyruvate (PEP), the initial acceptor of CO2 in the C4 photosynthetic pathway. PPDK activities in the leases of transgenic potatoes were up to 5.4‐fold higher than those of control potato plants (wild‐type and treated control plants). In the transgenic potato plants, PPDK activity in leaves was negatively correlated with pyruvate content (r2 = 0.81), and was positively correlated with malate content (r2 = 0.88). A significant increase in the δ13 C value was observed in the transgenic potato plants, suggesting a certain contribution of PEP carboxylase as the initial acceptor of atmospheric CO2 . These data suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C4 ‐type carbon metabolism. However, since parameters associated with CO2 gas exchange were not affected, the altered carbon metabolism had only a small effect on the total photosynthetic characteristics of the transgenic plants. 相似文献
17.
1. Applying Keeling plot techniques to derive δ13 C of respiratory input in a closed non-equilibrated chamber can lead to large errors because steady-state diffusion rules are violated in a non-steady-state environment. To avoid these errors, respiratory δ13 C can be derived using equilibrated closed chambers.
2. We introduce a new method to obtain stem respired CO2 δ13 C (δst - r ) with closed equilibrated stem chambers (E-SC). We present a theoretical model describing the equilibration process, test the model against field data and find excellent agreement. The method is further tested by comparing it with closed non-equilibrated stem chambers (NE-SC); we found no difference between these methods.
3. Our theoretical model to describe CO2 diffusion from the respiratory pool into the chamber and the equation to derive the δ13 C of the efflux are general. They could be applied to other ecosystem components (e.g. soils).
4. Our method is easy to implement, cost effective, minimizes sources of error and allows for rigorous leak detection. One major limitation is its inability to detect rapid change; the equilibration process requires 15 ± 2 h. A second limitation is that it cannot be used for species that produce abundant pitch at sites of stem wounding (e.g. Pseudotsuga menziesii ).
5. Investigating δ13 C of CO2 respired by different ecosystem components is necessary to interpret δ13 C of ecosystem respiration. This parameter has major implications with respect to global carbon cycle science. 相似文献
2. We introduce a new method to obtain stem respired CO
3. Our theoretical model to describe CO
4. Our method is easy to implement, cost effective, minimizes sources of error and allows for rigorous leak detection. One major limitation is its inability to detect rapid change; the equilibration process requires 15 ± 2 h. A second limitation is that it cannot be used for species that produce abundant pitch at sites of stem wounding (e.g. Pseudotsuga menziesii ).
5. Investigating δ
18.
Tracing carbon and oxygen isotope signals from newly assimilated sugars in the leaves to the tree-ring archive 总被引:1,自引:0,他引:1
ARTHUR GESSLER ELKE BRANDES NINA BUCHMANN GERHARD HELLE HEINZ RENNENBERG & ROMAIN L. BARNARD 《Plant, cell & environment》2009,32(7):780-795
The analysis of δ 13 C and δ 18 O in tree-ring archives offers retrospective insights into environmental conditions and ecophysiological processes. While photosynthetic carbon isotope discrimination and evaporative oxygen isotope enrichment are well understood, we lack information on how the isotope signal is altered by downstream metabolic processes.
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ18 O) or the newly assimilated carbon ( δ 13 C), via phloem sugars to the tree-ring, over a time-scale that ranges from hours to a growing season.
Seasonally, variable13 C enrichment of sugars related to phloem loading and transport did lead to uncoupling between δ 13 C in the tree-ring, and the c i / c a ratio at the leaf level. In contrast, the oxygen isotope signal was transferred from the leaf water to the tree-ring with an expected enrichment of 27‰, with time-lags of approximately 2 weeks and with a 40% exchange between organic oxygen and xylem water oxygen during cellulose synthesis.
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ13 C and δ 18 O in tree-ring ecology. 相似文献
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ
Seasonally, variable
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ
19.
Minghua Song Deyu Duan Hui Chen Qiwu Hu Feng Zhang Xingliang Xu Yuqiang Tian Hua Ouyang Changhui Peng 《Ecography》2008,31(4):499-508
Leaf δ13 C is an indicator of water-use efficiency and provides useful information on the carbon and water balance of plants over longer periods. Variation in leaf δ13 C between or within species is determined by plant physiological characteristics and environmental factors. We hypothesized that variation in leaf δ13 C values among dominant species reflected ecosystem patterns controlled by large-scale environmental gradients, and that within-species variation indicates plant adaptability to environmental conditions. To test these hypotheses, we collected leaves of dominant species from six ecosystems across a horizontal vegetation transect on the Tibetan Plateau, as well as leaves of Kobresia pygmaea (herbaceous) throughout its distribution and leaves of two coniferous tree species ( Picea crassifolia, Abies fabri ) along an elevation gradient throughout their distribution in the Qilian Mountains and Gongga Mountains, respectively. Leaf δ13 C of dominant species in the six ecosystems differed significantly, with values for evergreen coniferous13 C values of the dominant species and of K. pygmaea were negatively correlated with annual precipitation along a water gradient, but leaf δ13 C of A. fabri was not significantly correlated with precipitation in habitats without water-stress. This confirms that variation of δ13 C between or within species reflects plant responses to environmental conditions. Leaf δ13 C of the dominant species also reflected water patterns on the Tibetan Plateau, providing evidence that precipitation plays a primary role in controlling ecosystem changes from southeast to northwest on the Tibetan Plateau. 相似文献
20.
We used stable carbon (δ13 C) and nitrogen (δ15 N) isotopes to assess the importance of benthic algae for the zooplankton individual growth in winter in a shallow, clear subarctic lake. The δ13 C values of calanoid ( Eudiaptomus graciloides ) and cyclopoid ( Cyclops scutifer ) zooplankton in autumn suggest a food resource of pelagic origin during the ice-free period. The zooplankton δ13 C values were high in spring compared to autumn. E. graciloides did not grow over winter and the change in δ13 C was attributed to a decrease in lipid content during the winter. In contrast, the increase in δ13 C values of C. scutifer over the winter was explained by their growth on organic carbon generated by benthic algae. The δ15 N of the C. scutifer food resource during winter was low compared to δ15 N of the benthic community, suggesting that organic matter generated by benthic algae was mainly channelled to zooplankton via 15 N-depleted heterotrophic bacteria. The results demonstrate that benthic algae can sustain zooplankton metabolic demands and growth during long winters, which, in turn, may promote zooplankton growth on pelagic resources during the summer. Such multi-chain omnivory challenges the view of zooplankton as mainly dependent on internal primary production and stresses the importance of benthic resources for the productivity of plankton food webs in shallow lakes. 相似文献