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First published online January 8, 2007
Journal of Experimental Biology 210, 278-289 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02643

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Total body oxygen stores and physiological diving capacity of California sea lions as a function of sex and age

Michael J. Weise^* and Daniel P. Costa

Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Center for Ocean Health, 100 Shaffer Road, Santa Cruz, CA 95060, USA

View larger version (28K): [in this window] [in a new window]   Fig. 1. Developmental changes in (A) hematocrit, (B) hemoglobin content and (C) mean corpuscular hemoglobin content as a function of body size in California sea lions from 5-month old pups to adults (5-month pups, N=13; 9-month pups, N=7; small juvenile, N=18; large juvenile, N=12; sub-adult male, N=15; adult male, N=22; 87 kg adult female, N=37). For all animals combined the relationship between body size and Hct was not significant (r2=0.01, P=0.413), whereas there was a significant linear relationship with Hb (r2=0.14, P<0.001) and MCHC (r2=0.06, P=0.009).

View larger version (19K): [in this window] [in a new window]   Fig. 2. Developmental changes in (A) absolute blood volume and (B) mass-specific blood volume with increasing body size in California sea lions from 5-month old pups to adults. There was a significant linear relationship during the development of absolute (r2=0.92, P<0.001) and mass-specific blood volume (r2=0.20, P<0.001).

View larger version (14K): [in this window] [in a new window]   Fig. 3. Mean muscle myoglobin content in relation to body size for California sea lions from 5-month old pups to adults. Line represents least-squares regression (r2=0.10, P=0. 001).

View larger version (12K): [in this window] [in a new window]   Fig. 4. Comparison of absolute total body oxygen stores in the blood, lung and muscle of California sea lions during their development from 5-month old pups to adults (131 kg; male and female combined). Adult female and male also compared to right of broken line. Percentage of oxygen stores in blood, lung and muscle are listed in text for each compartment.

View larger version (6K): [in this window] [in a new window]   Fig. 5. Muscle myoglobin as a function of body size for male and female California sea lions from pup size through adulthood. The relationship between body size and myoglobin was significant for males (y=0.005x+2.56; r2=0.36, P<0.001) and females (y=0.03x+1.95; r2=0.78, P<0.001), and the rate of development was significantly different for the sexes.

View larger version (15K): [in this window] [in a new window]   Fig. 6. Mass-specific (A) blood oxygen stores, (B) muscle oxygen stores and (C) total oxygen stores as a function of body size was significant for male and female California sea lions. The relationship between body size and mass-specific blood oxygen stores was significant for females (y=0.094x+12.66; r2=0.20, P=0.002) and males (y=0.03x+14.29; r2=0.99, P=0.001), and significant for muscle oxygen stores in females (y=0.14x+9.13; r2=0.78, P<0.001) and males (y=0.02x+12.06; r2=0.37, P<0.001), and total oxygen stores for females (y=0.23x+30.04; r2=0.50, P<0.001) and males (y=0.07x+35.60; r2=0.30, P<0.001). However, the rate of development in mass-specific muscle oxygen stores was greater in females than males, although no greater in blood and total oxygen stores.