| Buoyancy under control: underwater locomotor performance in a deep diving seabird suggests respiratory strategies for reducing foraging effort. | |
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MedLine Citation:
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PMID: 20352122 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Because they have air stored in many body compartments, diving seabirds are expected to exhibit efficient behavioural strategies for reducing costs related to buoyancy control. We study the underwater locomotor activity of a deep-diving species from the Cormorant family (Kerguelen shag) and report locomotor adjustments to the change of buoyancy with depth. METHODOLOGY/PRINCIPAL FINDINGS: Using accelerometers, we show that during both the descent and ascent phases of dives, shags modelled their acceleration and stroking activity on the natural variation of buoyancy with depth. For example, during the descent phase, birds increased swim speed with depth. But in parallel, and with a decay constant similar to the one in the equation explaining the decrease of buoyancy with depth, they decreased foot-stroke frequency exponentially, a behaviour that enables birds to reduce oxygen consumption. During ascent, birds also reduced locomotor cost by ascending passively. We considered the depth at which they started gliding as a proxy to their depth of neutral buoyancy. This depth increased with maximum dive depth. As an explanation for this, we propose that shags adjust their buoyancy to depth by varying the amount of respiratory air they dive with. CONCLUSIONS/SIGNIFICANCE: Calculations based on known values of stored body oxygen volumes and on deep-diving metabolic rates in avian divers suggest that the variations of volume of respiratory oxygen associated with a respiration mediated buoyancy control only influence aerobic dive duration moderately. Therefore, we propose that an advantage in cormorants--as in other families of diving seabirds--of respiratory air volume adjustment upon diving could be related less to increasing time of submergence, through an increased volume of body oxygen stores, than to reducing the locomotor costs of buoyancy control. |
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Authors:
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Timothée R Cook; Akiko Kato; Hideji Tanaka; Yan Ropert-Coudert; Charles-André Bost |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-03-23 |
Journal Detail:
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Title: PloS one Volume: 5 ISSN: 1932-6203 ISO Abbreviation: PLoS ONE Publication Date: 2010 |
Date Detail:
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Created Date: 2010-03-30 Completed Date: 2011-01-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101285081 Medline TA: PLoS One Country: United States |
Other Details:
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Languages: eng Pagination: e9839 Citation Subset: IM |
Affiliation:
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DST/NRF Centre of Excellence, Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa. timothee.cook@gmail.com |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Behavior, Animal Biomechanics Birds / physiology* Diving / physiology* Energy Metabolism* Female Male Movement Oxygen / metabolism Oxygen Consumption Predatory Behavior / physiology* Respiration Swimming |
| Chemical | |
Reg. No./Substance:
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7782-44-7/Oxygen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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