Diving from the Roman Ruins

Diving from the Roman Ruins, originally uploaded by Stuck in Customs.

"The range of foraging behaviors available to deep-diving, air-breathing marine vertebrates is constrained by their physiological capacity to breath-hold dive. We measured body oxygen stores (blood volume and muscle myoglobin) and diving behavior in adult female northern elephant seals, Mirounga angustirostris, to investigate age-related effects on diving performance," scientists writing in the Journal of Experimental Biology report (see also Women's Health).

"Blood volume averaged 74.4 +/- 17.0 liters in female elephant seals or 20.2 +/- 2.0% of body mass. Plasma volume averaged 32.2 +/- 7.8. liters or 8.7 +/- 0.7% of body mass. Absolute plasma volume and blood volume increased independently with mass and age. Hematocrit decreased weakly with mass but did not vary with age. Muscle myoglobin concentration, while higher than previously reported (7.4 +/- 0.7. g%), did not vary with mass or age. Pregnancy status did not influence blood volume. Mean dive duration, a proxy for physiological demand, increased as a function of how long seals had been at sea, followed by mass and hematocrit. Strong effects of female body mass (range, 218-600. kg) on dive duration, which were independent of oxygen stores, suggest that larger females had lower diving metabolic rates. A tendency for dives to exceed calculated aerobic limits occurred more frequently later in the at-sea migration," wrote J.L. Hassrick and colleagues, University of California.

The researchers concluded: "Our data suggest that individual physiological state variables and condition interact to determine breath-hold ability and that both should be considered in life-history studies of foraging behavior."

Hassrick and colleagues published their study in the Journal of Experimental Biology (Condition and mass impact oxygen stores and dive duration in adult female northern elephant seals. Journal of Experimental Biology, 2010;213(4):585-592).

Additional information can be obtained by contacting J.L. Hassrick, University of California, Inst Marine Sci, 100 Shaffer Rd., Santa Cruz, CA 95060, USA.

The publisher of the Journal of Experimental Biology can be contacted at: Company of Biologists Ltd., Bidder Building Cambridge Commercial Park Cowley Rd., Cambridge CB4 4DL, Cambs, England.

Keywords: City:Santa Cruz, State:CA, Country:United States, Obstetrics, Physiology, Pregnancy, Women's Health

This article was prepared by Women's Health Weekly editors from staff and other reports. Copyright 2010, Women's Health Weekly via NewsRx.com.

Source Citation
"Researchers at University of California publish new data on women's health." Women's Health Weekly 11 Mar. 2010: 421. Academic OneFile. Web. 11 Mar. 2010.
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