Bioenergietics of the bottlenose dolphin (Tursiops truncatus) Bioenergetics of the bottlenose dolphin (Tursiiops truncatus)

Date
1995
Authors
Magee, Michelle Coyne
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Abstract
There are numerous species of marine mammals found throughout the earth's oceans and waterways. The study of marine mammal energetics is an attempt to define the flow of energy in homeotherms adapted to an aqueous environment. Their lifestyle is different than terrestrial mammals and must compensate for the challenging thermoregulatory requirements of water survival. Field studies of free-ranging animals are difficult, since continual direct observation and measurements are impossible. It is important to conduct controlled laboratory studies, from which to build a foundation of physiological principles on these mammals. The objectives of this research project were to investigate the bioenergetic scheme of the bottlenose dolphin under controlled laboratory-like conditions. Morphometric data in a large bottlenose dolphin population established an equation to predict age from length measurements in juvenile animals. The decrease in caloric intake seen with aging is in agreement with terrestrial mammals, and the importance of nutritional planning based on calories per kilogram body weight versus total calories fed was explained. Increased activity levels required increased caloric consumption, the amount being related to the degree of activity. A recently developed method to assess blubber volume using ultrasound are compared to standard measurements of body condition, weight-length ratio and condition index, and found to be a valid technique in this species. Blubber insulation was found to be more important than surface area in controlling environmental heat loss. Using stable isotopes of water, body composition, lean body mass and fat mass, were determined. An increase in fat mass, with a concurrent decrease in lean body mass, was observed in adult bottlenose dolphins, similar to terrestrial mammals. Also, consumption of a high fat diet contributed to an increase in body fat. Metabolic rates declined with age in bottlenose dolphins, and a significant increase was observed with low fat diets. Finally, the use of doubly labeled water to determine metabolic rate in free-ranging bottlenose dolphins was compared to the intake balance method and found to be an accurate technique in this species. The drawbacks of controlled laboratory trials is that, although all attempts are made to mimic diets and conditions that exist in the wild, the methods are only an approximation of wild conditions. The advantages are the ability to isolate and evaluate individual parameters and ensure adequate and timely data collection. It is essential to combine laboratory and field studies in order to elucidate the bioenergetic mechanisms and physiological adaptations of marine mammals. Although marine mammals have evolved specialized compensatory adaptations to ensure success in an aquatic environment, they follow the same general principles observed in terrestrial mammals. This research supports the concept of evolution and the relationship of all homeotherms, despite differences in ecological niches.
Description
Title printed with error on title page: "Bioenergietics of the bottlenose dolphin (Tursiops truncatus)"
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995.
Includes bibliographical references (leaves 131-143).
Microfiche.
xii, 143 leaves, bound 29 cm
Keywords
Bioenergetics, Bottlenose dolphin -- Physiology
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Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Biomedical Sciences (Physiology); no. 3148
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