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DNA metabarcoding and stable isotope analysis have significantly advanced our understanding of marine trophic ecology, aiding systematic research on foraging habits and species conservation. In this study, we employed these methods to analyse faecal and blood samples, respectively, to compare the trophic ecology of two Red-billed Tropicbird (Phaethonaethereus; Linnaeus, 1758) colonies on Mexican islands in the Pacific. Trophic patterns among different breeding stages were also examined at both colonies. Dietary analysis reveals a preference for epipelagic fish, cephalopods, and small crustaceans, with variations between colonies and breeding stages. Isotopic values (δ15N and δ13C) align with DNA metabarcoding results, with wider niches during incubation stages. Differences in diet are linked to environmental conditions and trophic plasticity among breeding stages, influenced by changing physiological requirements and prey availability. Variations in dietary profiles reflect contrasting environmental conditions affecting local prey availability.
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Código de Barras de DNA Taxonômico , Cadeia Alimentar , Animais , Isótopos de Carbono/análise , Dieta , Isótopos de Nitrogênio/análise , Aves/fisiologia , MéxicoRESUMO
The southern Mendoza province, located in the northern region of Patagonia, was inhabited by hunter-gatherer groups until historic times. Previous archaeological studies have reported canid remains among faunal assemblages, which were assumed to be part of the human diet. However, the taxonomic identification and significance of these canids within human groups have raised questions. In this study, we used ancient DNA analysis, morphological examination and stable isotope analysis (δ13Ccol and δ15N) to re-evaluate the taxonomic assignment of a canid discovered at the Late Holocene burial site of Cañada Seca. Previous morphological identifications suggested that it belonged to the genus Lycalopex, but our results conclusively demonstrate that the individual belongs to the extinct fox species Dusicyon avus. This finding expands Dusicyon avus' known geographical distribution to Patagonia's northern extremity. Furthermore, statistical predictions based on genetic divergence undermine the hypothesis that hybridization between Canis and Dusicyon, facilitated by the introduction of domestic dogs, played a role in the extinction of Dusicyon species. On the other hand, our findings indicate that a Dusicyon avus individual shared a similar diet and was probably buried alongside humans, suggesting a close relationship between the two species during their lives and deaths.
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Estuarine mangroves are often considered nurseries for the Atlantic Goliath grouper juveniles. Yet, the contributions of different estuarine primary producers and habitats as sources of organic matter during early ontogenetic development remain unclear. Given the species' critically endangered status and protection in Brazil, obtaining biological samples from recently settled recruits in estuaries is challenging. In this study, we leveraged a local partnership with fishers and used stable isotope (C and N) profiles from the eye lenses of stranded individuals or incidentally caught by fishery to reconstruct the trophic and habitat changes of small juveniles. The eye lens grows by the apposition of protein-rich layers. Once these layers are formed, they become inert, allowing to make inferences on the trophic ecology and habitat use along the development of the individual until its capture. We used correlations between fish size and the entire eye lens size, along with estuarine baselines, to reconstruct the fish size and trophic positions for each of the lens layers obtained. We then used dominant primary producers and basal sources from mangrove sheltered, exposed estuarine and marine habitats to construct an ontogenetic model of trophic and habitat support changes since maternal origins. Our model revealed marine support before the juveniles reached 25 mm (standard length), followed by a rapid increase in reliance on mangrove sheltered sources, coinciding with the expected size at settlement. After reaching 60 mm, individuals began to show variability. Some remained primarily supported by the mangrove sheltered area, while others shifted to rely more on the exposed estuarine area around 150 mm. Our findings indicate that while mangroves are critical for settlement, as Goliath grouper juveniles grow, they can utilize organic matter produced throughout the estuary. This underscores the need for conservation strategies that focus on seascape connectivity, as protecting just one discrete habitat may not be sufficient to preserve this endangered species and safeguard its ecosystem functions.
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Ecossistema , Espécies em Perigo de Extinção , Cristalino , Animais , Cristalino/crescimento & desenvolvimento , Brasil , Estuários , Isótopos de Carbono/análise , Isótopos de Nitrogênio/análise , Bass/fisiologia , Bass/crescimento & desenvolvimento , Cadeia Alimentar , Monitoramento AmbientalRESUMO
Submarine groundwater discharges (SGD) have been associated with important sources of nutrients between the land and oceans that can generate eutrophication conditions. This study aims to analyze the behavior of nitrogen and phosphorus using the mixing curve method, to examine the variation of the trophic state using the Karydis Index, and to evaluate the δ15N in benthic organisms to trace the origin of nitrogen in neap tide (November) and spring tide (January) in the Manatí Cenote, and Nohoch-Teek reef lagoon in the Mexican Caribbean. Nitrogen and phosphate enrichment was in the Manatí Cenote during neap and spring tides. This enrichment was particularly noticeable in the reef lagoon during low tides in the areas influenced by SGD. In the Cenote, differences in the nitrate trophic state were observed, indicating an eu-mesotrophic condition during neap tide and a mesotrophic condition during spring tide. However, no significant differences were observed for ammonium (oligo-mesotrophic), nitrites, or phosphate compounds (oligotrophic). The trophic state reef lagoon exhibited a similar pattern but with different spatial variations. In both systems, phosphorus was a limiting nutrient, while δ15N suggested anthropogenic nitrogen uptake by several benthic organisms.
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Different tissues are used for stable isotope analysis in cetacean investigations. However, variation in the isotopic composition of tissues with different turnover rates has been reported for cetaceans. To better understand stable carbon and nitrogen isotopes (δ13C and δ15N) in skin compared to other tissues, this study assessed the isotopic variation among the liver, muscle, and skin of Guiana dolphins (Sotalia guianensis), as well as the influence of sex on these variations. No differences were found in δ13C among male tissues, but females showed lower values in the liver compared to muscle and skin. Differences in δ15N were observed among all tissues, with different variation patterns for males and females. Four females were distinguished from males and other females by their 13C depletion in all tissues and δ15N variation pattern. We conclude that skin and muscle may be equivalent in δ13C values for Guiana dolphins. The multiple-tissue analysis brings new insights into their feeding ecology and provides background for stable isotope analysis using non-destructive sampling techniques in small cetaceans.
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Golfinhos , Animais , Feminino , Masculino , Golfinhos/fisiologia , Carbono , Isótopos de Nitrogênio/análise , Isótopos de Carbono/análise , EcologiaRESUMO
Mercury is a metal of toxicological importance that occurs naturally. However, its concentration can be affected by anthropogenic activities and has the potential to bioaccumulate and biomagnify in food webs. Thus, knowing how its concentration varies along the trophic levels allows us to understand its potential risks to the biota. The present study aimed to investigate mercury transfer through the Stenella frontalis food web in Ilha Grande Bay (IGB), Rio de Janeiro state, Brazil. Samples of muscle and liver of S. frontalis were obtained from carcasses (n = 8) found stranded in the IGB, and its potential prey species were collected in fishing landings in the same Bay (n = 145). Total mercury (THg) concentrations were determined by atomic absorption spectrometry, and the δ15N was determined by an isotope ratio mass spectrometer. To investigate how trophic transfer affects mercury contamination in biota, six linear models were applied between THg logarithmic concentrations and δ15N or trophic position (TP). The trophic magnification factor (TMF) was calculated from each model to estimate the trophic transfer. Mean THg concentration in S. frontalis was higher in the liver than in muscle, but no correlation was found with age and δ15N values. Instead, the hepatic and muscular THg concentrations positively correlated with the trophic position. In the summer, THg concentration, TP, and δ15N values in prey species varied significantly, as well as in the winter, except for THg concentration. All trophic transfer models were significant in both seasons, and the TMF >1. The present study showed that trophic transfer is an essential factor in mercury biomagnification in both seasons but is not the unique driver. Both δ15N and TP could explain mercury trophic transfer, but TP better integrates metabolic diversity and seasonality.
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Golfinhos , Mercúrio , Stenella , Poluentes Químicos da Água , Animais , Mercúrio/análise , Stenella/metabolismo , Bioacumulação , Golfinhos/metabolismo , Brasil , Cadeia Alimentar , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Peixes/metabolismoRESUMO
Mercury (Hg) is a contaminant of global concern due to its damaging toxicological effects on organisms. For the vulnerable Dusky Grouper (Epinephelus marginatus) off the coast of Brazil, we investigated: i) spatial patterns in muscle tissue total mercury (THg) contamination; ii) the relationship between muscle THg concentrations and total length iii) the relationship between muscle THg and stable isotopes; and iv) THg concentrations among muscle, liver, and ovary tissues. Out of 134 fish sampled, 21.8 % were higher than 0.5 mg/kg wet weight (above the safe limit for human consumption). THg concentrations increased toward lower latitudes, but an opposite pattern was observed for δ13C and δ15N with decreased values toward lower latitudes. There were significant differences in THg concentration among the three tissues. Results of Hg concentrations are useful for understanding the potential adverse effects on the health of this vulnerable species and to serve as a guide to human consumers.
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Bass , Mercúrio , Poluentes Químicos da Água , Animais , Humanos , Feminino , Mercúrio/análise , Brasil , Poluentes Químicos da Água/análise , Peixes , Isótopos/análise , Análise Espacial , Monitoramento AmbientalRESUMO
Stable isotope (SI) analysis is a standard tool to study marine food webs, usually based on the measurement of a few individuals from a small list of subjectively pre-defined species. The main objective of this study was to find out which species are significantly associated with the temporal variability of the SI composition of zooplankton in a tropical marine ecosystem. We investigated this by means of a novel species-biomass-isotopes-mixture (SBIM) approach that uses a relative biomass matrix to explain the SI signature of the zooplankton community. Furthermore, SBIM was applied to detect key taxa that can be considered bioindicators for important descriptors of ecosystem state (e.g., oligotrophy, carbon sources, mean trophic level). Plankton samples (64 µm mesh size) were obtained in Tamandaré Bay (northeastern Brazil) from June 2013 to August 2019. One aliquot of each sample was taken for stable isotope measurements and one for taxonomic identification and estimation of size and relative biomass. Total zooplankton biomass differed significantly between years, seasons and stations. Total zooplankton δ13C values ranged from -21.0 to -18.2 (mean ± standard deviation: -19.7 ± 0.7 in the dry season, and -19.4 ± 0.8 in the rainy season). Total zooplankton δ15N values ranged from 3.8 to 9.0 (7.0 ± 1.0 in the dry season, and 6.5 ± 1.2 rainy season). Total zooplankton C/N ratios ranged from 3.5 to 5.0 (4.2 ± 0.4 in the dry season and 4.2 ± 0.3 in the rainy season). The sparsely abundant and relatively large-sized copepod Pseudodiaptomus acutus was the most important species for explaining the variability in δ15N (22% of the total variability). Relative biomass (%) of P. acutus showed a strong positive correlation with δ15N, indicating a high trophic level (TL). Our results highlight the importance of less abundant taxa for marine food webs. Small-sized invertebrate larvae were negatively correlated with δ15N, indicating a TL below average. The copepod Dioithona oculata was the most important organism in explaining the δ13C of zooplankton (17.7% of the total variability, positive correlation with δ13C), indicating possible selective use of a13C-enriched food source (e.g., diatoms) by this cyclopoid copepod. Oithona spp. juveniles showed a negative relationship with zooplankton C/N ratio, which can be indicators of an oligotrophic ecosystem state and lipid-poor zooplankton. The tintinnid F. ehrenbergii showed a positive correlation with C/N, being an indicator for turbid "green waters'', during the rainy season, when the ecosystem was in a eutrophic state, with high lipid contents in the zooplankton community. The proposed SBIM approach opens up a novel pathway to understanding the factors and species that shape the temporal variability of food webs.
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Copépodes , Ecossistema , Animais , Isótopos de Carbono/análise , Cadeia Alimentar , Lipídeos , Isótopos de Nitrogênio/análise , Fatores de Tempo , Zooplâncton/metabolismoRESUMO
BACKGROUND: The natural abundance of stable isotope 15 N (δ15 N) in production systems has emerged as an alternative to distinguish organic products from conventional ones. This study evaluated the use of δ15 N values recorded for nitrogen fertilizers, soil and plant tissue in order to set the differences between organic and conventional agricultural production systems applied to rice, potatoes, apple and banana crops. RESULTS: Values of δ15 N recorded for N sources ranged from +5.58 to +18.27 and from -3.55 to +3.19 in organic and synthetic fertilizers, respectively. Values recorded for δ15 N in food from organic rice, potatoes and banana farms were higher than values recorded for δ15 N in conventional farms; the same was observed for values recorded for δ15 N in leaves from the four crops. CONCLUSION: Results have allowed for differentiation between production systems due to values of δ15 N recorded in leaves of all crops and food, for rice, potatoes and banana trees. © 2021 Society of Chemical Industry.
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Alimentos Orgânicos/análise , Alimentos Orgânicos/normas , Isótopos de Nitrogênio/análise , Certificação , Qualidade dos Alimentos , Malus/química , Musa/química , Oryza/química , Solanum tuberosum/químicaRESUMO
Mangrove environments are important for maintaining biodiversity and carbon cycling. However, these systems are being degraded at alarming rates around the world, particularly in rapidly developing regions. Here, we examine a sediment profile from a mangrove forest near a large port complex at Suape, northeast Brazil, in order to assess the impact of rapid urbanization and industrialization. We find that total organic carbon (TOC) and total nitrogen (TN) accumulation rates have increased in the estuary since the 1980's, directly related to rapid urban development. The TN and heavy δ15N values in the sediment column suggest increasing anthropogenic influences. In contrast, heavy metal fluxes did not increase during these transitions. The increase in TOC and TN accumulation rates during the past four decades highlight the significant role mangrove areas play as sinks for anthropogenically enhanced nutrients in poorly-understood tropical areas.
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Carbono , Sedimentos Geológicos , Brasil , Carbono/análise , Monitoramento Ambiental , Nutrientes , Áreas AlagadasRESUMO
Road dust is an indicator widely used when monitoring contamination and evaluating environmental and health risks in urban ecosystems. We conducted an exhaustive characterization of road dust samples coupling their chemical characteristics and stable isotope compositions (C and N) with the aim of evaluating the levels and spatial distribution of local contamination as well as to identify its main source(s) in the coastal city of Cienfuegos (Cuba). Results indicate that the concentrations of several elements (total nitrogen, S, Ca, V, Cu, Zn, Mo, Sn, Hg, and Pb) exceed the background values reported for both Cuban soils and the upper continental crust (UCC) and showed a high variability among the sampling sites. We show that road dust contamination in Cienfuegos induces high associated ecological risks. Among the studied elements, Cd and Hg are the major contributors to the environmental contamination in the city, mainly along busy roads and downtown. δ13C and δ15N, coupled to a multivariate statistical analysis, help associate the studied elements to several local sources of contamination: mineral matter derived from local soils, cement plant and related activities, road pavement alteration, power plant, road traffic, and resuspension of particulate organic matter (POM). Our results suggest that incorporating the chemical and isotope monitoring of road dust may help implement more effective environmental management measures in order to reduce their adverse impact on ecosystems and human health.
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Poeira/análise , Monitoramento Ambiental , Metais Pesados/análise , Isótopos de Carbono , Cidades , Cuba , Isótopos de Nitrogênio , Medição de RiscoRESUMO
The goals of this study were to analyze if there is a difference in the stable isotopic ratio (δ13C and δ15N) of macrobenthic species sampled at two sandy beaches (one close to a river mouth and the other far from any freshwater input) and to identify differences in the stable isotopic ratio (δ13C and δ15N) in different body parts of three representative species of two Brazilian sandy beach macrofaunas: the polychaete Hemipodia californiensis, the mollusk bivalve Donax hanleyanus, and the crustacean decapod Emerita brasiliensis. No significant differences were detected in the δ13C stable isotopic ratio between the two sites analyzed; however, in the δ15N stable isotopic ratio, a significant difference was observed. Regarding the intraspecific response of stable isotopic ratio, D. hanleyanus showed a significant difference in carbon among different body part structures, while a trend for significance was observed for nitrogen isotopes. The differences were significant for both isotopes in E. brasiliensis, and no differences were observed among the body part structures in H. californiensis. There were significant differences in E. brasiliensis carapaces with regard to the δ15N stable isotopic ratio between the muscle and the whole body. Although the δ13C and δ15N stable isotopic ratio differs significantly in the digestive tract, muscles, and whole body of D. hanleyanus, such differences were not enough to determine changes in their trophic levels and food sources. Similar stable isotopic ratios were observed in the whole body, proboscis, and teeth of H. californiensis, highlighting this species as the top predator. In conclusion, stable isotopic analysis of benthic trophic structure can be employed as a tool in coastal management plans or environmental impact studies.
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Monitoramento Ambiental , Poluentes da Água/análise , Animais , Praias , Bivalves , Brasil , Carbono/análise , Isótopos de Carbono/análise , Decápodes , Cadeia Alimentar , Isótopos de Nitrogênio/análise , Nutrientes , RiosRESUMO
Objectives: There is a lack of data in Panama on the potential differences in total healthcare professional (HCP) time between routine administrations of short-acting erythropoietin simulating agents (ESAs) (i.e. epoetin alfa) and continuous erythropoietin receptor activator (CERA) (i.e. methoxy polyethylene glycol-epoetin beta). This study aimed to quantify the HCP time associated with a single administration of epoetin alfa and CERA for the treatment of anemic patients with chronic kidney disease (CKD) on hemodialysis. Methods: This was a multi-center, cross-sectional study, using a time-and-motion methodology. Costs related to HCP time and consumables usage associated with administration of epoetin alfa and CERA were estimated. Results: Based on 60 administrations of either CERA or epoetin alfa, the estimated savings in mean total active HCP time were 2.34 (95% confidence interval = 1.87-2.81) min (-30%) per administration. When extrapolating to a full year's treatment with intravenous ESA, it would require a total of 20.3 (95% CI = 19.90-20.71) h of HCP time for epoetin alfa vs 1.1 (95% CI = 1.01-1.19) h for CERA per patient per year. Estimated savings in active HCP time per patient per year were 19.20 (95% CI = 19.20-19.21) h (-95%). This, in turn, translates into staff cost efficiency that favors Mircera with an estimated annual saving of $78.24 (95% CI = 78.24-78.28) (-95%) per patient. Conclusions: Data from a real-world setting showed that the adoption of CERA could potentially lead to a reduction in active HCP time. Highlights Few comparative data have explored the costs and potential savings of using long-acting erythropoietin-stimulating agents (ESA) instead of short-acting ESAs to treat anemia in CKD patients on hemodialysis. This time-and-motion study shows that use of CERA reduces total healthcare professional time and could represent a save for an institution in a real-world setting in Panama.
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Epoetina alfa/economia , Eritropoetina/economia , Pessoal de Saúde/economia , Hematínicos/economia , Polietilenoglicóis/economia , Anemia/tratamento farmacológico , Anemia/etiologia , Estudos Transversais , Custos de Medicamentos , Epoetina alfa/administração & dosagem , Eritropoetina/administração & dosagem , Feminino , Pessoal de Saúde/estatística & dados numéricos , Hematínicos/administração & dosagem , Humanos , Masculino , Panamá , Polietilenoglicóis/administração & dosagem , Diálise Renal/efeitos adversos , Insuficiência Renal Crônica/terapia , Fatores de TempoRESUMO
Evaluating long-term drivers of foraging ecology and population productivity is crucial for providing ecological baselines and forecasting species responses to future environmental conditions. Here, we examine the trophic ecology and habitat use of North Atlantic leatherback turtles (St. Croix nesting population) and investigate the effects of large-scale oceanographic conditions on leatherback foraging dynamics. We used bulk and compound-specific nitrogen isotope analysis of amino acids (CSIA-AA) to estimate leatherback trophic position (TP) over an 18-year period, compare these estimates with TP estimates from a Pacific leatherback population, and elucidate the pre-nesting habitat use patterns of leatherbacks. Our secondary objective was to use oceanographic indices and nesting information from St. Croix leatherbacks to evaluate relationships between trophic ecology, nesting parameters, and regional environmental conditions measured by the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation. We found no change in leatherback TP over time and no difference in TP between Atlantic and Pacific leatherbacks, indicating that differences in trophic ecology between populations are an unlikely driver of the population dichotomy between Pacific and Atlantic leatherbacks. Isotope data suggested that St. Croix leatherbacks inhabit multiple oceanic regions prior to nesting, although, like their conspecifics in the Pacific, individuals exhibit fidelity to specific foraging regions. Leatherback nesting parameters were weakly related to the NAO, which may suggest that positive NAO phases benefit St. Croix leatherbacks, potentially through increases in resource availability in their foraging areas. Our data contribute to the understanding of leatherback turtle ecology and potential mechanistic drivers of the dichotomy between populations of this protected species.
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Espécies em Perigo de Extinção , Tartarugas , Animais , Ecossistema , Oceanos e Mares , Ilhas Virgens AmericanasRESUMO
Tools to study seasonal changes in animal diets are needed to address a wide range of ecological questions. This is especially true of migratory animals that experience distinct environments where diets may be substantially different. However, tracking diets of individuals that move vast distances has proven difficult. Compound-specific isotope analysis has emerged as a valuable tool to study diets but has been little used to study dietary changes of migratory animals. Using this technique, we quantify seasonal variation in the annual diet of a migratory songbird (gray-cheeked thrush, Catharus minimus) and test the hypothesis that migrants change their diet in response to the energetic requirements of different periods of the annual cycle. By measuring δ13C and δ15N values of amino acids from feathers grown on the breeding grounds, blood formed during migration and claw grown on the wintering grounds, we found that migration is associated with greater consumption of fruit, compared to the breeding or wintering periods. This was confirmed by the lower trophic position of blood compared to feather and claw, by a decrease in the δ15N value of the source amino acid phenylalanine in blood as a function of days of stopover, and by the positive correlation between δ15N and δ13C values of phenylalanine in blood, and not in feather or claw. This study illustrates how isotopic analysis of amino acids can contribute to understand food webs, seasonal dietary changes and metabolic routing of nutrients in migratory animals.
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Aves Canoras , Aminoácidos , Migração Animal , Animais , Dieta , Isótopos , Isótopos de Nitrogênio , Estações do AnoRESUMO
In this paper we use high quality data from two developing countries, Ethiopia and Peru, to estimate the production functions of human capital from age 1 to age 15. We characterize the nature of persistence and dynamic complementarities between two components of human capital: health and cognition. We also explore the implications of different functional form assumptions for the production functions. We find that more able and higher income parents invest more, particularly at younger ages when investments have the greatest impacts. These differences in investments by parental income lead to large gaps in inequality by age 8 that persist through age 15.
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In this review, we examine the variation in stable isotope signatures of the lighter elements (δ2H, δ13C, δ15N, δ18O, and δ34S) of tissues and excreta of domesticated animals, the factors affecting the isotopic composition of animal tissues, and whether stable isotopes may be used to differentiate organic and conventional modes of animal husbandry. The main factors affecting the δ13C signatures of livestock are the C3/C4 composition of the diet, the relative digestibility of the diet components, metabolic turnover, tissue and compound specificity, growth rate, and animal age. δ15N signatures of sheep and cattle products have been related mainly to diet signatures, which are quite variable among farms and between years. Although few data exist, a minor influence in δ15N signatures of animal products was attributed to N losses at the farm level, whereas stocking rate showed divergent findings. Correlations between mode of production and δ2H and δ18O have not been established, and only in one case of an animal product was δ34S a satisfactory marker for mode of production. While many data exist on diet-tissue isotopic discrimination values among domesticated animals, there is a paucity of data that allow a direct and statistically verifiable comparison of the differences in the isotopic signatures of organically and conventionally grown animal products. The few comparisons are confined to beef, milk, and egg yolk, with no data for swine or lamb products. δ13C appears to be the most promising isotopic marker to differentiate organic and conventional production systems when maize (C4) is present in the conventional animal diet. However, δ13C may be unsuitable under tropical conditions, where C4 grasses are abundant, and where grass-based husbandry is predominant in both conventional and organic systems. Presently, there is no universal analytical method that can be applied to differentiate organic and conventional animal products.
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Laticínios/análise , Ovos/análise , Inspeção de Alimentos/métodos , Qualidade dos Alimentos , Alimentos Orgânicos/análise , Carne/análise , Modelos Químicos , Animais , Biomarcadores/análise , Bovinos , Laticínios/normas , Gema de Ovo/química , Ovos/normas , Rotulagem de Alimentos , Alimentos Orgânicos/normas , Humanos , Isótopos , Gado , Carne/normas , Produtos da Carne/análise , Produtos da Carne/normas , Leite/química , Leite/normas , Aves DomésticasRESUMO
Sheep are used in many countries as food and for manufacturing bioproducts. However, when these animals consume animal by-products (ABP), which is widely prohibited, there is a risk of transmitting scrapie - a fatal prion disease in human beings. Therefore, it is essential to develop sensitive methods to detect previous ABP intake to select safe animals for producing biopharmaceuticals. We used stable isotope ratio mass spectrometry (IRMS) for 13C and 15N to trace animal proteins in the serum of three groups of sheep: 1 - received only vegetable protein (VP) for 89 days; 2 - received animal and vegetable protein (AVP); and 3 - received animal and vegetable protein with animal protein subsequently removed (AVPR). Groups 2 and 3 received diets with 30% bovine meat and bone meal (MBM) added to a vegetable diet (from days 16-89 in the AVP group and until day 49 in the AVPR group, when MBM was removed). The AVPR group showed 15N equilibrium 5 days after MBM removal (54th day). Conversely, 15N equilibrium in the AVP group occurred 22 days later (76th day). The half-life differed between these groups by 3.55 days. In the AVPR group, 15N elimination required 53 days, which was similar to this isotope's incorporation time. Turnover was determined based on natural 15N signatures. IRMS followed by turnover calculations was used to evaluate the time period for the incorporation and elimination of animal protein in sheep serum. The δ13C and δ15N values were used to track animal protein in the diet. This method is biologically and economically relevant for the veterinary field because it can track protein over time or make a point assessment of animal feed with high sensitivity and resolution, providing a low-cost analysis coupled with fast detection. Isotopic profiles could be measured throughout the experimental period, demonstrating the potential to use the method for traceability and certification assessments.
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Ração Animal/análise , Dieta/veterinária , Proteínas Alimentares/análise , Espectrometria de Massas/veterinária , Ovinos , Animais , Isótopos de Carbono/análise , Espectrometria de Massas/métodos , Isótopos de Nitrogênio/análiseRESUMO
This study aimed to estimate trophic discrimination factors (TDFs) and metabolic turnover rates of nitrogen and carbon stable isotopes in blood and muscle of the smallnose fanskate Sympterygia bonapartii by feeding six adult individuals, maintained in captivity, with a constant diet for 365 days. TDFs were estimated as the difference between δ(13) C or δ(15) N values of the food and the tissues of S. bonapartii after they had reached equilibrium with their diet. The duration of the experiment was enough to reach the equilibrium condition in blood for both elements (estimated time to reach 95% of turnover: C t95%blood = 150 days, N t95%blood = 290 days), whilst turnover rates could not be estimated for muscle because of variation among samples. Estimates of Δ(13) C and Δ(15) N values in blood and muscle using all individuals were Δ(13) Cblood = 1·7, Δ(13) Cmuscle = 1·3, Δ(15) Nblood = 2·5 and Δ(15) Nmuscle = 1·5, but there was evidence of differences of c.0·4 in the Δ(13) C values between sexes. The present values for TDFs and turnover rates constitute the first evidence for dietary switching in batoids based on long-term controlled feeding experiments. Overall, the results showed that S. bonapartii has relatively low turnover rates and isotopic measurements would not track seasonal movements adequately. The estimated Δ(13) C values in S. bonapartii blood and muscle were similar to previous estimations for elasmobranchs and to generally accepted values in bony fishes (Δ(13) C = 1·5). For Δ(15) N, the results were similar to published reports for blood but smaller than reports for muscle and notably smaller than the typical values used to estimate trophic position (Δ(15) N c. 3·4). Thus, trophic position estimations for elasmobranchs based on typical Δ(15) N values could lead to underestimates of actual trophic positions. Finally, the evidence of differences in TDFs between sexes reveals a need for more targeted research.
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Isótopos de Carbono/metabolismo , Isótopos de Nitrogênio/metabolismo , Rajidae/metabolismo , Animais , Isótopos de Carbono/análise , Isótopos de Carbono/sangue , Isótopos de Carbono/química , Dieta , Comportamento Alimentar/fisiologia , Feminino , Masculino , Músculos/química , Músculos/metabolismo , Isótopos de Nitrogênio/análise , Isótopos de Nitrogênio/sangue , Isótopos de Nitrogênio/química , Estado NutricionalRESUMO
The role of matter and energy flow across ecosystem boundaries for the subsidized consumer populations is well known. However, little is known on the effects of allochthonous subsidies on food web structure and trophic niche dimensions of consumers in the tropics. We excluded allochthonous aquatic insects from tropical streams using greenhouse-type exclosures to test the influence of aquatic allochthonous subsidies on the trophic structure and niche dimensions of terrestrial predators using stable isotope methods. In exclosure treatments, abundance and biomass of terrestrial predators, and biomass of phytophages decreased and increased, respectively. Vegetation-living predators were more responsive to allochthonous inputs than those living on the ground. Overall, lower availability of allochthonous inputs did not affect community-wide metrics and niche width of predators. However, the niche width of some spider families had very low overlap between treatments, and others had wider isotopic niches in the control than in the exclusion treatment. Most of the C and N in predators living in control stretches came from aquatic subsidies, and those predators living in the exclusion treatments switched their diets to terrestrial sources, showing a preference of predators for allochthonous subsidies. Our results suggest that allochthonous subsidies are also relevant to tropical fauna living upon vegetation. Moreover, allochthonous resources may amplify the niche dimension of certain predators or considerably change the trophic niche of others. Our study highlights the importance of including modern isotopic tools in elucidating the role of allochthonous resources on the patterns of trophic structure and niche dimensions of consumers from donor ecosystems.