Effect of temperature and ration size on carbon and nitrogen stable isotope trophic fractionation
Article first published online: 12 JAN 2007
Volume 21, Issue 2, pages 356–362, April 2007
How to Cite
BARNES, C., SWEETING, C. J., JENNINGS, S., BARRY, J. T. and POLUNIN, N. V. C. (2007), Effect of temperature and ration size on carbon and nitrogen stable isotope trophic fractionation. Functional Ecology, 21: 356–362. doi: 10.1111/j.1365-2435.2006.01224.x
- Issue published online: 12 JAN 2007
- Article first published online: 12 JAN 2007
- Received 15 March 2006; accepted 5 October 2006 Editor: John Speakman
- Dicentrarchus labrax;
- European sea bass;
- food web;
- 1Stable isotope data are widely used to track the origins and transformations of materials in food webs. Reliable interpretation of these data requires knowledge of the factors influencing isotopic fractionation between diet and consumer. For practical reasons, isotopic fractionation is often assumed to be constant but, in reality, a range of factors may affect fractionation.
- 2To investigate effects of temperature and feeding rate on fractionation of carbon and nitrogen stable isotopes in a marine predator, we reared European sea bass Dicentrarchus labrax on identical diets at 11 and 16 °C on three ration levels for 600 days.
- 3Nitrogen trophic fractionation (Δδ15N) was affected by temperature. Bass Δδ15N was 4·41‰ at 11 °C and 3·78‰ at 16 °C.
- 4Carbon fractionation (Δδ13C) was also affected by temperature. Bass Δδ13C was 1·18‰ at 11 °C and 1·64‰ at 16 °C. The higher lipid content in the tissues of bass reared at cooler temperatures accounted for the temperature effect on Δδ13C. When Δδ13C was determined using mathematically defatted values, there was a direct effect of ration size and Δδ13C was 2·51, 2·39 and 2·31‰ for high, medium and low rations, respectively.
- 5Reported Δδ15N for all treatments exceeded the mean of 3·4‰ widely used in ecological studies of fish populations and communities. This would confound the interpretation of δ15N as an indicator of trophic level when comparing populations that are exposed to different temperatures.
- 6The Δδ13C of 0–1‰ commonly applied in food web studies did not hold under any of the temperature or feeding regimes considered and a value of 2‰ would be more appropriate.