Steller sea lion research > Nutritional Stress >Energy Requirements > Thermoregulation & Diving

Measuring Energy Expenditures: Thermoregulation

To understand the relationship between food intake and sea lion health, it is important to measure the costs associated with various activities, including swimming, thermoregulation, resting metabolism, field metabolic rate, and diving.

Thermoregulation
Steller sea lions are well adapted to a life spent in the cold waters of the North Pacific. However, it still takes energy to maintain a constant deep body temperature. This is known as the cost of thermoregulation.

Young Steller sea lions might have to expend more energy to stay warm when water temperatures approach the freezing point, since they have less blubber to use as insulation against the cold. With the help of a specially-designed water-chiller that can lower water temperatures to mimic those found in the natural environment, Dr. David Rosen (UBC) has been measuring how much energy sea lions use at different water temperatures at different ages and during different seasons. Dr. Rosen has also tested whether the heat released by digestion can be used to help keep sea lions warm in cold water.

A recent study by Kate Willis (Texas A&M) examined where heat is lost on a sea lion's body. Using specifically designed equipment, Ms. Willis mapped out the amount of heat that was lost at a sea lion's "hot spots" and "cold spots" while swimming in water at different temperatures.

In theory, the less blubber a sea lion has, the more energy it must expend to stay warm. A study by Lisa Hoopes and Dr. Graham Worthy (University of Central Florida) measures how animal nutrition, blubber reserves, and water temperature combine to affect thermal demands.

These studies by Consortium scientists are designed to help understand how changes in the Steller sea lion’s environment (climate, food) may be contributing to their population decline.

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Thermoregulation Related papers:

Hoopes, L.A., L.D. Rea, D.A.S. Rosen and G.A.J. Worthy. 2004.  Effects of body condition on resting metabolism in captive and free-ranging Steller sea lions (Eumetopias jubatus). Symposia of the Comparative Nutrition Society 2004 5:79-82.

Rosen, D.A.S. and A.W. Trites. 2003. No evidence for bioenergetic interaction between digestion and thermoregulation in Steller sea lions, Eumetopias jubatus.   Physiological and Biochemical Zoology 76(6):899-906.

updated 19 Feb. 2007