摘要：Abstract Stable isotope analysis (SIA) measurements from long-term captivity studies provide required parameters for interpretation of consumer SIA data. We raised young-of-the-year (14–19 cm) California yellowtail ( Seriola dorsalis ) on a low δ 15 N and δ 13 C diet (pellet aquaculture feed) for 525 days, then switched to a high δ 15 N and δ 13 C diet (mackerel and squid) for 753 days. Yellowtail muscle was sequentially sampled from each individual after the diet switch (0 to 753 days) and analyzed for δ 15 N and δ 13 C, allowing for calculation of diet-tissue discrimination factors (DTDFs) from two isotopically different diets (low δ 15 N and δ 13 C: pellets; high δ 15 N and δ 13 C: fish/squid) and turnover rates of 15 N and 13 C. DTDFs were diet dependent: Δ 15 N = 5.1‰, Δ 13 C = 3.6‰ for pellets and Δ 15 N = 2.6‰, Δ 13 C = 1.3‰ for fish/squid. Half-life estimates from 15 N and 13 C turnover rates for pooled yellowtail were 181 days and 341 days, respectively, but varied considerably by individual ( 15 N: 99–239 d; 13 C: 158–899 d). Quantifying DTDFs supports isotopic approaches to field data that assume isotopic steady-state conditions ( e.g ., mixing models for diet reconstruction). Characterizing and quantifying turnover rates allow for estimates of diet/habitat shifts and “isotopic clock” approaches, and observed inter-individual variability suggests the need for large datasets in field studies. We provide diet-dependent DTDFs and growth effects on turnover rates, and associated error around these parameters, for application to field-collected SIA data from other large teleosts.
其他摘要：Abstract Stable isotope analysis (SIA) measurements from long-term captivity studies provide required parameters for interpretation of consumer SIA data. We raised young-of-the-year (14–19 cm) California yellowtail ( Seriola dorsalis ) on a low δ 15 N and δ 13 C diet (pellet aquaculture feed) for 525 days, then switched to a high δ 15 N and δ 13 C diet (mackerel and squid) for 753 days. Yellowtail muscle was sequentially sampled from each individual after the diet switch (0 to 753 days) and analyzed for δ 15 N and δ 13 C, allowing for calculation of diet-tissue discrimination factors (DTDFs) from two isotopically different diets (low δ 15 N and δ 13 C: pellets; high δ 15 N and δ 13 C: fish/squid) and turnover rates of 15 N and 13 C. DTDFs were diet dependent: Δ 15 N = 5.1‰, Δ 13 C = 3.6‰ for pellets and Δ 15 N = 2.6‰, Δ 13 C = 1.3‰ for fish/squid. Half-life estimates from 15 N and 13 C turnover rates for pooled yellowtail were 181 days and 341 days, respectively, but varied considerably by individual ( 15 N: 99–239 d; 13 C: 158–899 d). Quantifying DTDFs supports isotopic approaches to field data that assume isotopic steady-state conditions ( e.g ., mixing models for diet reconstruction). Characterizing and quantifying turnover rates allow for estimates of diet/habitat shifts and “isotopic clock” approaches, and observed inter-individual variability suggests the need for large datasets in field studies. We provide diet-dependent DTDFs and growth effects on turnover rates, and associated error around these parameters, for application to field-collected SIA data from other large teleosts.
