Journal Article

Tissue Turnover Rates and Isotopic Trophic Discrimination Factors in the Endothermic Teleost, Pacific Bluefin Tuna (Thunnus orientalis)

Litvin, Steven Y., Popp, Brian N., Madigan, Daniel J., Block, Barbara A., Carlisle, Aaron B., Farwell, Charles J.

2012

Overview

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.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Analysis / Animal behavior / Animal Migration / Animal tissues / Animals / Atlantic bluefin tuna / Biology / Captivity / Carbon / Carbon Isotopes - chemistry / Carbon Isotopes - metabolism / Diet / Ecological monitoring / Ecology / Ecosystems / Endothermic reactions / Fish / Foraging behavior / Half-Life / Isotopes / Kinetics / Laboratories / Lamnidae / Liver / Liver - metabolism / Marine animals / Muscle Fibers, Fast-Twitch - metabolism / Muscles / Nitrogen / Nitrogen (Chemical element) / Nitrogen Isotopes - chemistry / Nitrogen Isotopes - metabolism / Pelagic zone / Researchers / Stable isotopes / Studies / Thunnus orientalis / Thunnus thynnus / Tissues / Tuna / Tuna - growth & development / Tuna - metabolism