scholarly journals Isotopic discrimination factors and nitrogen turnover rates in reared Atlantic bluefin tuna larvae (Thunnus thynnus): effects of maternal transmission

2016 ◽  
Vol 80 (4) ◽  
pp. 447 ◽  
Author(s):  
Amaya Uriarte ◽  
Alberto García ◽  
Aurelio Ortega ◽  
Fernando De la Gándara ◽  
José Quintanilla ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Bluefin Tuna ◽  
Gilthead Seabream ◽  
Half Time ◽  
Turnover Rates ◽  
Thunnus Thynnus ◽  
Data Set ◽  
Nitrogen Turnover ◽  
Discrimination Factors

The use of stable isotope analysis to study animal diets requires estimates of isotopic turnover rates (half time, t50) and discrimination factors (Δ) for an accurate interpretation of trophic patterns. The stable isotopes of carbon and nitrogen were analysed for eggs and reared larvae of Thunnus thynnus, as well as for the different diets supplied during the experiment. The results showed high values of δ15N in eggs and larvae (n=646) until 4 DAH. After this time lapse, the stable isotope values declined progressively until 12 DAH, when notochord flexion began. The δ13C showed an inverse trend, suggesting that maternal inheritance of the stable isotopes is evident until pre-flexion stages. This study proposes a model for estimating maternal isotopic signatures of bluefin broodstock. After notochord flexion, larvae were fed with aquaculture-bred gilthead seabream, which resulted in a rapid increase of bluefin larvae δ15N values together with a rapid decrease in δ13C values. The estimated nitrogen half-time to reach the steady state from the diet was 2.5±0.3 days and the discrimination factor was 0.4±0.3(‰). These results represent the first data set that has allowed isotopic nitrogen turnover rates and discrimination factors of the larval stages of bluefin tuna to be estimated.

Isotopic fractionation and turnover in captive Garden Warblers (Sylvia borin): implications for delineating dietary and migratory associations in wild passerines

2003 ◽  
Vol 81 (9) ◽  
pp. 1630-1635 ◽  
Author(s):  
Keith A Hobson ◽  
Franz Bairlein
Keyword(s):  
Stable Isotopes ◽  
Isotopic Fractionation ◽  
Carbon Turnover ◽  
Stable Carbon ◽  
Turnover Rates ◽  
Exponential Decay Model ◽  
N Isotopes ◽  
Discrimination Factors ◽  
Sylvia Borin ◽  
Element Turnover

There is currently a great deal of interest in using stable-isotope methods to investigate diet and migratory connections in wild passerines. To apply these methods successfully, it is important to understand how stable isotopes discriminate or change between diet and the tissue of interest and what the element-turnover rates are in metabolically active tissues. Of particular use are studies that sample birds non-destructively through the use of blood and feathers. We investigated patterns of isotopic discrimination between diet and blood and feathers of Garden Warblers (Sylvia borin) raised on an isotopically homogeneous diet (48% C, 5% N) and then switched to one of two experimental diets, mealworms (56.8% C, 8.3% N) and elderberries, Sambucus niger (47.4% C, 1.5% N). We established that the discrimination factors between diet and blood appropriate for stable carbon (δ13C) and nitrogen (δ15N) isotopes are +1.7‰ and +2.4‰, respectively. For feathers, these values were +2.7‰ and +4‰, respectively. Turnover of elemental nitrogen in whole blood was best approximated by an exponential-decay model with a half-life of 11.0 ± 0.8 days (mean ± SD). Corresponding turnover of carbon was estimated to range from 5.0 ± 0.7 to 5.7 ± 0.8 days. We conclude that this decoupling of nitrogen- and carbon-turnover rates can be explained by differences in metabolic routing of dietary macromolecules. Our results suggest that tracking frugivory in migratory passerines that switch diets between insects and fruits may be complicated if only a trophic-level estimate is made using δ15N measurements.

scholarly journals Tissue Turnover Rates and Isotopic Trophic Discrimination Factors in the Endothermic Teleost, Pacific Bluefin Tuna (Thunnus orientalis)

PLoS ONE ◽  
2012 ◽  
Vol 7 (11) ◽  
pp. e49220 ◽  
Author(s):  
Daniel J. Madigan ◽  
Steven Y. Litvin ◽  
Brian N. Popp ◽  
Aaron B. Carlisle ◽  
Charles J. Farwell ◽  
...  
Keyword(s):  
Bluefin Tuna ◽  
Pacific Bluefin Tuna ◽  
Turnover Rates ◽  
Thunnus Orientalis ◽  
Tissue Turnover ◽  
Discrimination Factors ◽  
Trophic Discrimination

scholarly journals Mechanisms of consistently disjunct soil water pools over (pore) space and time

2019 ◽  
Vol 23 (6) ◽  
pp. 2751-2762 ◽  
Author(s):  
Matthias Sprenger ◽  
Pilar Llorens ◽  
Carles Cayuela ◽  
Francesc Gallart ◽  
Jérôme Latron
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Soil Water ◽  
Soil Depth ◽  
Stream Water ◽  
Pore Space ◽  
Bound Water ◽  
Subsurface Water ◽  
Data Set ◽  
Soil Pores

Abstract. The storage and release of water in soils is critical for sustaining plant transpiration and groundwater recharge. However, how much subsurface mixing of water occurs, and how much of the water is available for plants or otherwise percolates to streams and the groundwater is not yet understood. Based on stable isotope (2H and 18O) data, some studies have found that water infiltrating into soils can bypass older pore water. However, the mechanisms leading to the separation of water routed to the streams and water held tightly in smaller pores are still unclear. Here, we address the current limitations of the understanding of subsurface mixing and their consequences regarding the application of stable isotopes in ecohydrological studies. We present an extensive data set, for which we sampled the isotopic composition of mobile and bulk soil water in parallel with groundwater at a fortnightly temporal resolution and stream water and rainfall at a much higher resolution in a Mediterranean long-term research catchment, in Vallcebre, Spain. The data reveal that the mobile and tightly bound water of a silty loam soil in a Scots pine forest do not mix well; however, they constitute two disjunct subsurface water pools with little exchange, despite intense rainfall events leading to high soil wetness. We show that the isotopic compartmentalization results from the rewetting of small soil pores by isotopically depleted winter/spring rain. Thus, stable isotopes, and, in turn, water residence times, do not only vary across soil depth, but also across soil pores. Our findings have important implications for stable isotope applications in ecohydrological studies assessing the water uptake by plants or the process realism of hydrological models, as the observed processes are currently rarely implemented in the simulation of water partitioning into evapotranspiration and recharge in the critical zone.

scholarly journals The Importance of Isotopic Turnover for Understanding Key Aspects of Animal Ecology and Nutrition

Diversity ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 84 ◽  
Author(s):  
Wales A. Carter ◽  
Ulf Bauchinger ◽  
Scott R. McWilliams
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Species Interactions ◽  
Turnover Rates ◽  
Ecological Studies ◽  
Marine Systems ◽  
Wide Range ◽  
Dietary Shifts ◽  
Key Aspects ◽  
Isotopic Turnover

Stable isotope-based methods have proved to be immensely valuable for ecological studies ranging in focus from animal movements to species interactions and community structure. Nevertheless, the use of these methods is dependent on assumptions about the incorporation and turnover of isotopes within animal tissues, which are oftentimes not explicitly acknowledged and vetted. Thus, the purpose of this review is to provide an overview of the estimation of stable isotope turnover rates in animals, and to highlight the importance of these estimates for ecological studies in terrestrial, freshwater, and marine systems that may use a wide range of stable isotopes. Specifically, we discuss 1) the factors that contribute to variation in turnover among individuals and across species, which influences the use of stable isotopes for diet reconstructions, 2) the differences in turnover among tissues that underlie so-called ‘isotopic clocks’, which are used to estimate the timing of dietary shifts, and 3) the use of turnover rates to estimate nutritional requirements and reconstruct histories of nutritional stress from tissue isotope signatures. As we discuss these topics, we highlight recent works that have effectively used estimates of turnover to design and execute informative ecological studies. Our concluding remarks suggest several steps that will improve our understanding of isotopic turnover and support its integration into a wider range of ecological studies.

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