724_Final Report.pdf - North Pacific Research Board

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Validating quantitative fatty acid signature analysis (QFASA) to estimate diets of spectacled and Steller’s eiders (Somateria fischeri and Polysticta stelleri) Shiway W. Wang 1 , Tuula E. Hollmen 1,2 , Sara J. Iverson 3 1 Alaska SeaLife Center, 301 Railway Avenue, PO Box 1329, Seward, Alaska 99664 USA, shiway@gmail.com 2 School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 201 Railway Avenue, PO Box 730, Seward, Alaska 99664 USA 3 Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, B3H 4J1 Canada 7
Abstract Fatty acid (FA) signature analysis has been used to study trophic relationships and foraging ecology in marine ecosystems. This powerful method provides information about diets over a longer period of time (e.g., 2-4 weeks) rather than just the most recent meal. Using a comprehensive database of diet FA signatures and accounting for consumer FA metabolism, it is possible to estimate the proportions of diet items in the consumer diet using quantitative FA signature analysis (QFASA). However, before applying QFASA to free ranging populations, ideally, a captive study is performed to assess the quantitative characteristics of the study species’ FA metabolism. We conducted feeding experiments to validate the use of QFASA in captive spectacled (N=8) and Steller’s eiders (N=8) as a minimally invasive method for studying the diets of these threatened birds. From the long-term feeding period, we assessed the quantitative characteristics of FA deposition and developed calibration coefficients (CCs) for individual FAs to account for eider lipid metabolism. We then tested the model and CCs by estimating the diets of the captive eiders. Our results revealed that QFASA accurately indicates diet and diet switches in captive eiders for these diet items. QFASA also confirmed that complete FA turnover of the new introduced diets was not complete by 21 or 29 days, and that diets could be estimated over an extended period of > 29 days. Thus, our understanding of diet can be backtracked to more than a month in feeding eiders. We conclude that applying QFASA techniques to eiders in the wild has the potential to provide valuable information about their diets at different life history stages. Key Words: fatty acids, diet, foraging ecology, Somateria fischeri, Polysticta stelleri 8
Page 1 and 2: NORTH PACIFIC RESEARCH BOARD PROJEC
Page 3 and 4: TABLE OF CONTENTS STUDY CHRONOLOGY
Page 5 and 6: snails (Petersen et al. 1998, Lovvo
Page 7 and 8: een employed in eiders to evaluate
Page 9: CHAPTER 1. Validating quantitative
Page 13 and 14: migration, or how the diets of juve
Page 15 and 16: were switched to Diet 3 which consi
Page 17 and 18: 16:1n-7, 18:0, 18:1n-9, 18:1n-7, 18
Page 19 and 20: The diets of captive eiders were es
Page 21 and 22: Calibration coefficients (CCs) and
Page 23 and 24: Discussion The results from this ca
Page 25 and 26: appropriate for estimating a consum
Page 27 and 28: Ideally, captive studies should mim
Page 29 and 30: Acknowledgments Financial support w
Page 31 and 32: Federal Register. 1997. Endangered
Page 33 and 34: Raclot, T., Groscolas, R., and Cher
Page 35 and 36: Table 2. Sum of the squared errors
Page 37 and 38: Figure 5. QFASA estimates using the
Page 39 and 40: Figure 2. 2nd discriminant function
Page 41 and 42: Figure 4. proportion proportion 1.0
Page 43 and 44: Appendix 1. Fatty acid (FA) subsets
Page 45 and 46: CONCLUSIONS The results from this c
Page 47 and 48: we incorporated into our calculatio
Page 49 and 50: There is still much work to be done
Page 51 and 52: ACKNOWLEDGEMENTS Funding was provid
Page 53 and 54: Harrison, N.M. 1984. Predation on j
Page 55: APPENDIX A: ASLC Fact Sheet 52

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