Ascent exhalations of Antarctic fur seals: a behavioural adaptation for breath-hold diving?

Hooker, Sascha K.; Miller, Patrick J.O.; Johnson, Mark P.; Cox, Oliver P.; Boyd, Ian L.. 2005 Ascent exhalations of Antarctic fur seals: a behavioural adaptation for breath-hold diving? Proceedings of the Royal Society of London, B, 272 (1561). 355-363.

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Novel observations collected from video, acoustic and conductivity sensors showed that Antarctic fur seals consistently exhale during the last 50–85% of ascent from all dives (10–160 m, n>8000 dives from 50 seals). The depth of initial bubble emission was best predicted by maximum dive depth, suggesting an underlying physical mechanism. Bubble sound intensity recorded from one seal followed predictions of a simple model based on venting expanding lung air with decreasing pressure. Comparison of air release between dives, together with lack of variation in intensity of thrusting movement during initial descent regardless of ultimate dive depth, suggested that inhaled diving lung volume was constant for all dives. The thrusting intensity in the final phase of ascent was greater for dives in which ascent exhalation began at a greater depth, suggesting an energetic cost to this behaviour, probably as a result of loss of buoyancy from reduced lung volume. These results suggest that fur seals descend with full lung air stores, and thus face the physiological consequences of pressure at depth. We suggest that these regular and predictable ascent exhalations could function to reduce the potential for a precipitous drop in blood oxygen that would result in shallow-water blackout.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Dynamics and Management of Ocean Ecosystems
ISSN: 1471-2954
Additional Keywords: Fur seals, Arctocephalus gazella, Diving, Physiology
NORA Subject Terms: Zoology
Date made live: 21 Dec 2007 14:50 +0 (UTC)

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