Estimating in situ isotopic turnover in Rainbow Trout (Oncorhynchus mykiss) muscle and liver tissue

Figures & data

Table 1. Summary (+/− 1 SD) statistics for prey, RBT, and hatchery feed δ¹³C and δ¹⁵N values by sampling date.

Days since stocking	Species	Tissue type	δ^13C	δ^15N	Sample size
0	RBT	Liver	−19.7 ± 0.2	8.9 ± 0.5	10
0	RBT	Muscle	−19.4 ± 0.3	9.9 ± 0.3	10
0	Hatchery feed	NA	−22.9 ± 0.1	5.3 ± 0.3	3
30	RBT	Liver	−24.5 ± 3.4	9.1 ± 1.1	10
30	RBT	Muscle	−22.1 ± 3.4	9.8 ± 1.1	10
30	Daphnia	Whole organism	−32.1 ± 1.4	7.0 ± 0.4	2
30	Chironomidae	Whole organism	−33.6 ± 3.6	7.1 ± 0.0	2
30	Chaoboridae	Whole organism	−32.3 ± 0.0	11.8 ± 0.3	2
30	Golden Shiner	Liver	−28.8 ± 1.4	9.6 ± 0.7	20
61	RBT	Liver	−26.0 ± 2.9	10.2 ± 1.0	7
61	RBT	Muscle	−23.1 ± 3.8	10.0 ± 1.5	7
61	Daphnia	Whole organism	−31.6 ± 0.7	6.3 ± 0.3	2
61	Chironomidae	Whole organism	−40.9 ± 7.6	3.4 ± 4.5	2
61	Chaoboridae	Whole organism	−31.8 ± 0.5	10.9 ± 0.9	2
91	RBT	Liver	−26.2 ± 2.7	10.5 ± 0.6	3
91	RBT	Muscle	−23.0 ± 3.4	10.2 ± 0.8	3
91	Daphnia	Whole organism	−32.3 ± 0.3	11.5 ± 0.3	2
91	Chironomidae	Whole organism	−35.9 ± 9.3	5.1 ± 3.8	2
91	Chaoboridae	Whole organism	−32.1 ± 1.0	12.3 ± 0.2	2
122	RBT	Liver	−25.3 ± 1.2	11.2 ± 0.8	4
122	RBT	Muscle	−22.1 ± 2.9	10.3 ± 1.1	4
122	Daphnia	Whole organism	−33.1 ± 0.8	9.9 ± 0.3	2
122	Chironomidae	Whole organism	−41.2 ± 8.6	3.9 ± 4.1	2
122	Chaoboridae	Whole organism	−31.1 ± 0.0	13.2 ± 0.6	2
122	Golden Shiner	Liver	−25.8 ± 1.6	8.9 ± 1.7	15
153	RBT	Liver	−27.7 ± 2.4	11.8 ± 0.8	8
153	RBT	Muscle	−24.4 ± 3.1	11.1 ± 0.9	8
153	Daphnia	Whole organism	−33.2 ± 0.7	10.3 ± 0.2	2
153	Chironomidae	Whole organism	−42.7 ± 10.1	2.5 ± 6.2	2
153	Chaoboridae	Whole organism	−32.2 ± 1.0	12.0 ± 1.2	2
183	RBT	Liver	−29.4 ± 2.6	11.1 ± 0.8	7
183	RBT	Muscle	−24.9 ± 2.9	10.9 ± 0.6	7
183	Daphnia	Whole organism	−37.3 ± 0.2	13.2 ± 0.5	2
183	Chironomidae	Whole organism	−35.3 ± 12.1	4.3 ± 3.3	2
183	Chaoboridae	Whole organism	−32.6	13.3	2

Note: RBT δ values have not been corrected to account for tissue discrimination here; discrimination values were applied prior to statistical analysis. Additionally, sample size for prey items does not represent total individuals, but rather unique sampling sites; all individuals sampled at a single site are pooled for stable isotope analysis.

Figure 1. Isotopic turnover trends for δ¹³C and δ¹⁵N in RBT liver (black line, filled circles) and white muscle (gray line, open circles). Given that tissue type did not have a significant effect on δ¹⁵N, after controlling for time (ANCOVA: F(1,90) = 2.200, p = 0.142), only one solid black regression line is shown for N. Dotted and dashed lines represent δ values of hatchery food and ‘lake diet’, respectively. Error bars represent ± 1 SD.