Slow isotope turnover rates and low discrimination values in the American alligator: implications for interpretation of ectotherm stable isotope data
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Material Information

Title:
Slow isotope turnover rates and low discrimination values in the American alligator: implications for interpretation of ectotherm stable isotope data
Series Title:
Physiological and Biochemical Zoology
Creator:
Rosenblatt, Adam E.
Heithaus, Michael R.
Publisher:
Florida Coastal Everglades Long Term Ecological Research
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Food chains (Ecology)
Stable isotope analysis
Genre:
article
serial ( sobekcm )
Spatial Coverage:
Everglades (Fla.)

Notes

Abstract:
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 δ15N discrimination values were surprisingly low in comparison to those of other top predators and varied between experimental and control alligators. The variability of δ15N discrimination values highlights the difficulties in using δ15N 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.
Citation/Reference:
Rosenblatt, A.E., M.R. Heithaus. 2013. Slow isotope turnover rates and low discrimination values for three tissues in the American alligator: implications for interpretation of ectotherm stable isotope data. Physiological and Biochemical Zoology 86: 137-148.

Record Information

Source Institution:
Florida International University
Rights Management:
Please contact the owning institution for licensing and permissions. It is the users responsibility to ensure use does not violate any third party rights.
Resource Identifier:
FI14082520
10.1086/668295 ( doi )