Tissue turnover rates and isotopic trophic discrimination factors in the endothermic teleost, pacific bluefin tuna (Thunnus orientalis)

PLoS One. 2012;7(11):e49220. doi: 10.1371/journal.pone.0049220. Epub 2012 Nov 7.

Abstract

Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver) and isotope- (nitrogen and carbon) specific turnover rates and trophic discrimination factors (TDFs) using archived tissues from captive Pacific bluefin tuna (PBFT), Thunnus orientalis, 1-2914 days after a diet shift in captivity. Half-life values for (15)N turnover in white muscle and liver were 167 and 86 days, and for (13)C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ(15)N and 1.8 and 1.2‰ for δ(13)C, respectively. Our results demonstrate that turnover of (15)N and (13)C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. (15)N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ(15)N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Migration*
  • Animals
  • Carbon Isotopes / chemistry
  • Carbon Isotopes / metabolism
  • Diet
  • Half-Life
  • Liver / metabolism*
  • Muscle Fibers, Fast-Twitch / metabolism*
  • Nitrogen Isotopes / chemistry
  • Nitrogen Isotopes / metabolism
  • Tuna / growth & development
  • Tuna / metabolism*

Substances

  • Carbon Isotopes
  • Nitrogen Isotopes

Grants and funding

This work was funded by the Tuna Research and Conservation Center, Monterey Bay Aquarium, and Lerner-Grey fund of the American Natural History Museum. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.