Diet‐tissue discrimination factors ( Δ 13 C and Δ 15 N ) and turnover rate in somatic tissues of a neotropical detritivorous fish on C 3 and C 4 diets

In this study, diet‐tissue discrimination factors and turnover rates were determined from the somatic tissues of a detritivorous fish Prochilodus lineatus . The carbon ( Δ 13 C ) and nitrogen ( Δ 15 N ) diet‐tissue discrimination factors varied for all feed rations with a range of Δ 13 C values between −1·9 and 3·6‰ and Δ 15 N between 3·3 and 5·7‰. Carbon turnover rate in the blood was 23·1 days for the C 3 ration and 34·7 days for the C 4 ration, in the liver was 9·9 days under the C 3 ration and nitrogen turnover rate was the same (23·1 days) in the liver for both C 4 and C 3 – C 4 rations, and 13·9 days in the muscle for C 3 – C 4 ration.