A Standardized Protocol for Measuring Bioelectrical Impedance in Green Turtles (Chelonia mydas)

Kophamel, Sara, Ward, Leigh C., Ariel, Ellen, Mendez, Diana, O'Brien, Lauren M., Burchell, Lauren, and Munns, Suzanne L. (2023) A Standardized Protocol for Measuring Bioelectrical Impedance in Green Turtles (Chelonia mydas). Physiological and Biochemical Zoology, 96 (2). pp. 87-99.

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Bioelectrical impedance analysis (BIA) is gaining popularity in wildlife studies as a portable technology for immediate and nondestructive predictions of body composition components, such as fat-free and fat masses. Successful application of BIA for field-based research requires the identification and control of potential sources of error, as well as the creation of and adherence to a standardized protocol for measurement. The aim of our study was to determine sources of error and to provide a standardization protocol to improve measurement precision of BIA on juvenile green turtles (Chelonia mydas; n=35 ). We assessed the effects of altered environmental temperature (20°C–30°C), postprandial state (2–72 h), and time out of the water (2 h) on five impedance parameters (resistance at infinite frequency [Rinf], resistance at zero frequency [R0], resistance at 50 kHz [R50], phase angle at 50 kHz [PhA50], and intracellular resistance [Ri]) using a bioimpedance spectroscopy device. Technical reproducibility of measurements and interanimal variability were also assessed. We found an inverse exponential relationship between change in environmental temperature and impedance parameters Rinf, R0, and R50. Postprandial state significantly increased Rinf and Ri 72 h after feeding. BIA measurements were reproducible within individual juvenile green turtles at temperatures from 20°C to 30°C. Significant variation in impedance values was found between animals at all temperatures, sampling times, and postprandial states, but the relative differences (%) were small in magnitude. Our study suggests that measurement precision is improved by measuring animals at consistent environmental temperatures close to their preferred thermal range. We propose a standardized protocol of measurement conditions to facilitate laboratory and field use of BIA for body composition assessment studies in turtles.

Item ID: 78111
Item Type: Article (Research - C1)
ISSN: 1537-5293
Keywords: bioelectrical impedance spectroscopy, bioelectrical impedance analysis (BIA), sea turtles, temperature, post-prandial state, resistance, reptile
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Copyright Information: © 2022 The University of Chicago. This work is licensed under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC 4.0), which permits non-commercial reuse of the work with attribution.
Date Deposited: 05 Apr 2023 23:27
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3009 Veterinary sciences > 300904 Veterinary diagnosis and diagnostics @ 50%
41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410401 Conservation and biodiversity @ 50%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180504 Marine biodiversity @ 100%
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