Influence of Forest Disturbance on Stable Nitrogen Isotope Ratios in Soil and Vegetation Profiles

2015 ◽  
Vol 79 (5) ◽  
pp. 1470-1481 ◽  
Author(s):  
Jennifer D. Knoepp ◽  
R. Scott Taylor ◽  
Lindsay R. Boring ◽  
Chelcy F. Miniat
Keyword(s):  
Forest Disturbance ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Stable Nitrogen Isotope

Do we excrete what we eat? Analysis of stable nitrogen isotope ratios of human urinary urea

2017 ◽  
Vol 31 (14) ◽  
pp. 1221-1227 ◽  
Author(s):  
Frank Hülsemann ◽  
Karsten Koehler ◽  
Ulrich Flenker ◽  
Wilhelm Schänzer
Keyword(s):  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Stable Nitrogen Isotope

What do harp seals eat? Comparing diet composition from different compartments of the digestive tract with diets estimated from stable-isotope ratios

2005 ◽  
Vol 83 (10) ◽  
pp. 1365-1372 ◽  
Author(s):  
M O Hammill ◽  
V Lesage ◽  
P Carter
Keyword(s):  
Digestive Tract ◽  
Large Intestine ◽  
Diet Composition ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Mixing Models ◽  
Stable Carbon ◽  
Stable Nitrogen Isotope ◽  
Hard Part ◽  
Pagophilus Groenlandicus

This study compared diet reconstructed from different compartments of the digestive tract of harp seals (Pagophilus groenlandicus (Erxleben, 1777)) with the diet estimated using stable carbon and stable nitrogen isotope ratios in mixing models. Diet composition in 18 feeding harp seals (mean age = 2.4 years, SD = 1.8 years, range = 0–6 years) was determined using traditional methods of hard-part identification and reconstruction, and stable carbon and stable nitrogen isotope ratios. Diet composition consisted of 68.8% (SD = 8.7%) and 69.6% (SD = 11.6%) by mass of invertebrates or 65.0% (SD = 8.8%) and 66.5% (SD = 11.8%) by energy of invertebrates for the stomach and small-intestine compartments, respectively. Reconstructed diets using material recovered from the large-intestine contents suggested a diet of 43.1% (SD = 12.2%) and 38.0% (SD = 11.9%) invertebrates using mass and energy, respectively. Stable carbon and stable nitrogen isotope ratios determined for the same individual harp seals suggested a diet consisting of approximately 66.1% (SD = 117.4) invertebrates, indicating that diet reconstructions based on hard parts from stomachs are likely to be more representative than reconstructions from large-intestine contents. In species that feed on a combination of vertebrates and invertebrates, the use of faecal material to reconstruct diet composition will likely underestimate the importance of invertebrates in the diet.

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