Physiological implications of continuous, prolonged, and deep dives of the southern elephant seal (Mirounga leonina)

Abstract

The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested that they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use physiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives.

Myoglobin oxygen affinity in aquatic and terrestrial birds and mammals

“…In order to maximize underwater foraging time, diving vertebrates typically dive within their ADL (Kooyman et al, 1980;Butler, 2004). Weddell seals (Kooyman et al, 1983), elephant seals (Hindell et al, 1992), bottlenose dolphins (Williams et al, 1999), macaroni penguins, and emperor penguins (Green et al, 2003) all make more than 90% of dives within their ADL. For species in this study without a published ADL or cADL, an ADL was estimated based on behavioral information using published mean dive durations plus one s.d.…”

A bioenergetic model for estimating the food requirements of Steller sea lions Eumetopias jubatus in Alaska, USA

“…Female survival rates from these studies were multiplied by 1.017 to obtain a finite rate of population increase (λ) of 1.0. Male maturity rates were estimated from Pitcher & Calkins (1981) (A water ) of 4.0 (2.5 to 5.5) for all animals (Costa & Gentry 1986, Costa et al 1989, Reilly & Fedak 1991, Castellini et al 1992, Hindell et al 1992, Arnould et al 1996. Population parameters.…”

High fatty acid oxidation capacity and phosphorylation control despite elevated leak and reduced respiratory capacity in northern elephant seal muscle mitochondria

“…Prominent among these impressive feats is that of the northern elephant seal (NES) [Mirounga angustirostris (Gill 1866)], which can dive for up to 2 h without resurfacing for air, reaching depths of up to 2000 m in water temperatures near 2°C (Robinson et al, 2012). Remarkably, NES are thought to rely almost exclusively on aerobic metabolism of lipids to meet energy demands during dives, despite the steady decline in oxygen (O 2 ) availability (Le Boeuf et al, 1988;Hindell et al, 1992;Le Boeuf et al, 1996;Meir et al, 2009). This is possible because of a number of physiological adjustments that maintain a supply of substrate and O 2 to muscle mitochondria in the absence of exogenous O 2 supply (Meir et al, 2009;Davis, 2014) and high biomechanical efficiency ('gliding') to reduce energy demands during dives (Williams et al, 2000).…”