Quantifying diet to tissue isotopic (δ¹³C and δ¹⁵N) fractionation factors in captive spectacled eiders (Somateria fischeri): implications for nutrient allocation and foraging studies

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Author
Federer, Rebekka
Chair
Hollmén, Tuula
Committee
Esler, Daniel
Wooller, Matthew
Keyword
Spectacled eider
Nutrition
Reproduction
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URI
http://hdl.handle.net/11122/12787
Abstract
"The spectacled eider (Somateria fischeri) was listed as threatened under the Endangered Species Act in 1993, and potential threats to population recovery include changes in the marine prey abundance and availability. Therefore, development of diet assessment techniques has been listed as an eider recovery task. Stable isotopes have been used to evaluate foraging ecology and nutrient allocation to reproduction in birds. Application of this technique requires knowledge of how stable isotope signatures of animal tissues differ from their diet, referred to as isotopic fractionation, and these values can be determined experimentally using captive populations. I established stable isotopic fractionation factors for d¹³C and d¹⁵N from diet to egg components, down feathers, contour feathers, cellular blood, blood plasma, and fat of captive spectacled eiders. Sensitivity analyses indicate that choice of isotopic fractionation values from eggs of different species could considerably alter model conclusions. Therefore, I incorporated isotopic fractionation factors from spectacled eider eggs into two published sea duck nutrient allocation models that previously used these values from falcons (Falco spp.) to assess differences in model conclusions. Results from these studies provide further resources to understand foraging and nutrient transfer in eiders and may offer more accurate estimates for sea duck models"--Leaf iii
Description
Thesis (M.S.) University of Alaska Fairbanks, 2009
Table of Contents
General introduction -- Sea duck declines and spectacled eider background -- Thesis background -- Thesis outline and goals -- References -- 1. Carbon and nitrogen stable isotope fractionation factors for quantifying spectacled eider (Somateria fischeri) nutrient allocation to egg production -- 1.1. Abstract -- 1.2. Introduction -- 1.3. Materials and methods -- 1.3.1. Study species -- 1.3.2. Diet and reproductive tissue collection -- 1.3.3. Laboratory analyses -- 1.3.4. Calculations and statistical analyses -- 1.4. Results -- 1.4.1. δ¹³C and δ¹⁵N isotope analyses for diet items --1.4.2. Δδ¹³C and Δδ¹⁵N for egg components and down feathers --1.4.3. Species comparison for isotopic egg fractionation and theoretical modeling -- 1.4.4. Differentiating macronutrient sources in Δδ¹³C and Δδ¹⁵N -- 1.5. Discussion -- 1.5.1. Spectacled eider egg and down isotopic fractionation -- 1.5.2. Potential factors contributing to variation in spectacled eider Δδ¹³C and Δδ¹⁵N -- 1.5.3. Species differences in Δδ¹³C and Δδ¹⁵N -- 1.5.4. Differentiating macronutrient sources -- 1.6. Acknowledgements -- 1.7. References -- 2. Stable carbon and nitrogen isotope fractionation factors from diet to cellular blood, blood plasma, feathers, and subcutaneous fat in spectacled eiders (Somateria fischeri) -- 2.1. Abstract -- 2.2. Introduction -- 2.3. Materials and methods -- 2.3.1. Study species -- 2.3.2. Diet and adult tissue collection -- 2.3.3. Laboratory analyses -- 2.3.4. Calculations and statistical analyses -- 2.4. Results -- 2.4.1. δ¹³C and δ¹⁵N istotope analyses for diet items -- 2.4.2. δ¹³C and δ¹⁵N isotope fractionation factors in adult tissues -- 2.5. Discussion -- 2.5.1. Stable isotope fractionation of spectacled eider blood components -- 2.5.2. Stable isotope fractionation of spectacled eider feathers -- 2.5.3. Stable isotope fractionation of spectacled eider subcutaneous fat -- 2.5.4. Conclusions and future recommendations -- 2.6. Acknowledgements -- 2.7. References -- 3. Evaluating sea duck nutrient allocation to reproduction model outcomes using diet to egg isotopic fractionation factors (Δδ¹³C and Δδ¹⁵N) derived from captive spectacled eiders (Somateria fischeri) -- 3.1. Abstract -- 3.2. Introduction -- 3.3. Materials and methods -- 3.4. Results -- 3.5. Discussion -- 3.6. Acknowledgements -- 3.7. References -- 3.8. Appendices -- General conclusions and future directions -- Thesis conclusions -- Future directions -- References.
Date
2009-08
Type
Thesis
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