Document Detail

Slow isotope turnover rates and low discrimination values in the American alligator: implications for interpretation of ectotherm stable isotope data.
MedLine Citation:
PMID:  23303328     Owner:  NLM     Status:  MEDLINE    
Stable isotope analysis has become a standard ecological tool for elucidating feeding relationships of organisms and determining food web structure and connectivity. There remain important questions concerning rates at which stable isotope values are incorporated into tissues (turnover rates) and the change in isotope value between a tissue and a food source (discrimination values). These gaps in our understanding necessitate experimental studies to adequately interpret field data. Tissue turnover rates and discrimination values vary among species and have been investigated in a broad array of taxa. However, little attention has been paid to ectothermic top predators in this regard. We quantified the turnover rates and discrimination values for three tissues (scutes, red blood cells, and plasma) in American alligators (Alligator mississippiensis). Plasma turned over faster than scutes or red blood cells, but turnover rates of all three tissues were very slow in comparison to those in endothermic species. Alligator δ(15)N discrimination values were surprisingly low in comparison to those of other top predators and varied between experimental and control alligators. The variability of δ(15)N discrimination values highlights the difficulties in using δ(15)N to assign absolute and possibly even relative trophic levels in field studies. Our results suggest that interpreting stable isotope data based on parameter estimates from other species can be problematic and that large ectothermic tetrapod tissues may be characterized by unique stable isotope dynamics relative to species occupying lower trophic levels and endothermic tetrapods.
Adam E Rosenblatt; Michael R Heithaus
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-11-05
Journal Detail:
Title:  Physiological and biochemical zoology : PBZ     Volume:  86     ISSN:  1537-5293     ISO Abbreviation:  Physiol. Biochem. Zool.     Publication Date:    2013 Jan-Feb
Date Detail:
Created Date:  2013-01-10     Completed Date:  2013-06-24     Revised Date:  2014-01-23    
Medline Journal Info:
Nlm Unique ID:  100883369     Medline TA:  Physiol Biochem Zool     Country:  United States    
Other Details:
Languages:  eng     Pagination:  137-48     Citation Subset:  IM    
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MeSH Terms
Alligators and Crocodiles / growth & development*,  metabolism*
Body Composition
Carbon / analysis,  blood
Carbon Isotopes / analysis,  blood
Epidermis / chemistry
Food Chain
Isotope Labeling / methods*
Nitrogen / analysis,  blood
Nitrogen Isotopes / analysis,  blood
Tissue Distribution
Reg. No./Substance:
0/Carbon Isotopes; 0/Nitrogen Isotopes; 7440-44-0/Carbon; N762921K75/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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