Stable isotope ratios of a tropical marine predator: confounding effects of nutritional status during growth

Stable isotope analysis of carbon and nitrogen is frequently used to study the diets and foraging ecology of marine predators. However, isotopic values may also be affected by an individual’s nutritional status and associated physiological processes. Here, we use C and N stable isotopes in blood and...

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Bibliographic Details
Published in:Marine biology 2012-04, Vol.159 (4), p.873-880
Main Authors: Lee Cruz, Larisa, McGill, Rona A. R., Goodman, Simon J., Hamer, Keith C.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Biomedical and Life Sciences
Body size
Foraging behavior
Fractionation
Freshwater & Marine Ecology
Fundamental and applied biological sciences. Psychology
Growth rate
Isotopes
Life Sciences
Marine
Marine & Freshwater Sciences
Marine biology
Marine ecology
Microbiology
Nutritional status
Oceanography
Original Paper
Physiology
Predation
Predators
Prey
Sea water ecosystems
Stable isotopes
Synecology
Zoology
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Summary:Stable isotope analysis of carbon and nitrogen is frequently used to study the diets and foraging ecology of marine predators. However, isotopic values may also be affected by an individual’s nutritional status and associated physiological processes. Here, we use C and N stable isotopes in blood and feathers of blue-footed booby chicks at the Galápagos Islands to examine how isotopic values are related to body condition and growth rate, and to assess the consistency in the isotope ratios of individuals during growth. Size dimorphism in blue-footed boobies provided an additional opportunity to examine how isotope ratios differ between sexes in relation to body size and growth rate. There was no significant difference between sexes but both C and N stable isotopes were significantly negatively related to the body condition of chicks. These data were consistent with individual variation in physiological processes affecting fractionation, although we cannot rule out the possibility that they were also influenced to some extent by population-level variation in the stable isotope ratios of prey fed to chicks, for instance related to prey size, depth or lipid content. Our results highlight the need for methods that take proper account of confounding physiological factors in isotopic studies of foraging ecology and diet.
ISSN:0025-3162
1432-1793
DOI:10.1007/s00227-011-1864-7