Relationships between isotopic values and oxidative status: insights from populations of gentoo penguins
Feeding strategies can affect the balance between the production of reactive oxygen species and antioxidant defences (i.e. oxidative status). This is ecologically relevant, as variation in oxidative status can in turn strongly affect fitness. However, how animals regulate their oxidative status through their feeding behaviour under natural conditions remains poorly understood. Thus, relating the isotopic values of free-ranging animals to their oxidative status may prove useful. Here, we considered three colonies of gentoo penguins (Pygoscelis papua) in which we measured (1) δ13C and δ15N values, and (2) antioxidant defences and oxidative damage. We found that colonies with the highest δ13C and δ15N values also had the highest levels of antioxidant defences and oxidative damage, resulting in positive relationships between isotopic values and markers of oxidative status. As a result, colony segregation in terms of isotopic values was reflected by segregation in terms of oxidative markers (although more markedly for oxidative damage than for antioxidant defences). Interestingly, variation in the estimated contribution of krill in the diet of penguins followed an opposite pattern to that observed for markers of oxidative status, providing evidence that inter-population differences in terms of foraging strategies can result in inter-population differences in terms of oxidative status. More studies examining simultaneously oxidative status, isotopic signature, foraging behaviour and food allocation between parents and young are, however, needed to understand better the interplay between the foraging strategies adopted by animals in their natural habitat and their oxidative status.
KeywordsAntarctica Diet Oxidative stress Penguins SIAR
This work was supported by the Antarctic Science Bursary. It receives supplementary support from the Instituto Antártico Chileno (INACH), American Ornithologist Union, and Sigma Xi. We thank the US Antarctic Marine Living Resources program, Raytheon Polar Services, G. Watters, and W. Trivelpiece for providing logistical support. Animal use was conducted under approved protocols from INACH (Project T-27-10), the University of North Carolina Wilmington (A0910-20), and a US National Science Foundation Antarctic Conservation Act permit provided to G. Watters (2011-005).
Conflict of interest
The authors declare no conflict of interest.
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