Efficacy of the Tritiated Water and 22Na Turnover Methods in Estimating Food and Energy Intake by Emperor Penguins Aptenodytes forsteri
The accuracy of the tritiated water (HTO) and sodium-22 () turnover methods as estimators of dietary water and sodium intake was evaluated in emperor penguins fed separate diets of squid and fish. Emperor penguins assimilated 76.2% and 81.8% of available energy in the squid and fish diets, respectiv...
| Published in: | Physiological Zoology |
|---|---|
| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
University of Chicago Press
1992
|
| Subjects: | |
| Online Access: | https://oceanrep.geomar.de/id/eprint/37526/ https://oceanrep.geomar.de/id/eprint/37526/1/2433.pdf https://doi.org/10.1086/physzool.65.5.30158551 |
| Summary: | The accuracy of the tritiated water (HTO) and sodium-22 () turnover methods as estimators of dietary water and sodium intake was evaluated in emperor penguins fed separate diets of squid and fish. Emperor penguins assimilated 76.2% and 81.8% of available energy in the squid and fish diets, respectively. Both isotopes had equilibrated with body water and exchangeable sodium pools by 2 h after intramuscular injection. The tritium method yielded reliable results after blood isotope levels had declined by 35%. On average the tritium method underestimated water intake by 2.9%, with a range of-10.3% to + 11.1%. The method underestimated Na intake on average by 15.9% with the errors among individuals ranging from -37.2% to -1.8%. Discrepancies with turnover were sign ficantly greater with the squid diet than the fish diet. The results confirm the reliability of the tritium method as an estimator of food consumption by free-living emperor penguins (provided seawater and freshwater ingestion is known) and support the adoption of the method to derive an approximation of seawater intake by tritiated emperor penguin chicks and by tritiated adults on foraging trips of short duration. |
|---|