Dataset Information

Coastal polynyas: Winter oases for subadult southern elephant seals in East Antarctica.

ABSTRACT: Antarctic coastal polynyas are regions of persistent open water and are thought to be key bio-physical features within the sea-ice zone. However, their use by the upper trophic levels of ecosystems remains unclear. A unique bio-physical dataset recorded by southern elephant seals reveals that East Antarctic polynyas are a key winter foraging habitat for male seals. During their post-moult trips from Isles Kerguelen to the Antarctic continental shelf, a total of 18 out of 23 seals visited 9 different polynyas, spending on average 25?±?20% (up to 75%) of their total trip time inside polynyas. Changes in seal foraging and diving behaviours are observed inside polynyas as compared to outside polynyas. Two polynya usages by seals are observed for the inactive and active polynya phases, pointing to different seasonal peaks in prey abundance. During the active polynya phase, we link seal foraging behaviour to changes in the physical stability of the water-column, which likely impact the seasonal biological dynamics within polynyas.

SUBMITTER: Labrousse S

PROVIDER: S-EPMC5816617 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Publications

Coastal polynyas: Winter oases for subadult southern elephant seals in East Antarctica.

Labrousse Sara S Williams Guy G Tamura Takeshi T Bestley Sophie S Sallée Jean-Baptiste JB Fraser Alexander D AD Sumner Michael M Roquet Fabien F Heerah Karine K Picard Baptiste B Guinet Christophe C Harcourt Robert R McMahon Clive C Hindell Mark A MA Charrassin Jean-Benoit JB

Scientific reports 20180216 1

Antarctic coastal polynyas are regions of persistent open water and are thought to be key bio-physical features within the sea-ice zone. However, their use by the upper trophic levels of ecosystems remains unclear. A unique bio-physical dataset recorded by southern elephant seals reveals that East Antarctic polynyas are a key winter foraging habitat for male seals. During their post-moult trips from Isles Kerguelen to the Antarctic continental shelf, a total of 18 out of 23 seals visited 9 diffe ...[more]

PMID: 29453356

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Project description:Southern elephant seal (Mirounga leonina) pups must strike a balance between conserving energy during their post-weaning fast and simultaneously developing diving abilities to attain nutritional independence. Little is known about environmental influences on cardiorespiratory patterns, hence energy use, throughout the 6?week fast. Continuous heart rates were recorded for free-ranging, newly weaned southern elephant seals using heart rate time-depth recorders for 5-9?days at Sub-Antarctic Macquarie Island, during October 1994 (n?=?1), 1995 (n?=?4) and 1996 (n?=?1). Daytime observations of respiration and behaviour were made throughout. We present the first instance of synchronous heart rate traces recorded simultaneously for individual weaners. Generalized additive models revealed that a sinusoidal pattern of diurnal heart rate elevation and nocturnal depression was evident in all seals and, on at least one occasion, a conspicuous break in this pattern coincided with an extreme cold weather event. Seals in this study were capable of considerable cardiorespiratory control and regularly demonstrated bradycardia during periods of resting apnoea. Apnoeic duration ranged from 33 to 291?s (mean 134?s). Apnoeic heart rates (mean 67?±?15?beats?min(-1), range 40-114?beats?min(-1)) were on average 19.7% lower than those exhibited during periods of eupnoea (mean 83?±?15?beats?min(-1), range 44-124?beats?min(-1)). The early development of the cardiorespiratory response is characterized by arrhythmic heart and respiration rates. The strong temporal patterns observed are being driven by the opposing requirements of maximizing time spent fasting in order to develop diving capabilities and of maximizing departure mass. This pilot study has highlighted a potentially large effect of ambient weather conditions on newly weaned southern elephant seal cardiorespiratory activity. Given the increasing westerlies and more erratic and increasing storminess associated with the Southern Annular Mode predicted in the Southern Ocean, the patterns observed here warrant further investigation.

Dataset Information

Coastal polynyas: Winter oases for subadult southern elephant seals in East Antarctica.

Publications

Coastal polynyas: Winter oases for subadult southern elephant seals in East Antarctica.

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