[MARMAM] New publication on the dive response in pinnipeds

Jeppe Kaczmarek jeppekaczmarek at gmail.com
Wed Aug 1 22:25:20 PDT 2018


Dear MARMAM community


We are pleased to announce a new research article in The Journal of
Experimental Biology on the dive response in pinnipeds.



*Drivers of the dive response in pinnipeds; apnea, submergence or
temperature?*

Jeppe Kaczmarek, Colleen Reichmuth, Birgitte I. McDonald, Jakob H.
Kristensen, Josefin Larson, Fredrik Johansson, Jenna L. Sullivan, Peter T.
Madsen

Journal of Experimental Biology 2018 : jeb.176545 doi: 10.1242/jeb.176545


*Abstract: *

Long and deep dives in marine mammals are enabled by high mass-specific
oxygen stores and the dive response (DR), which reduces oxygen consumption
in concert with increased peripheral vasoconstriction and a lowered heart
rate during dives. Diving heart rates of pinnipeds are highly variable and
modulated by many factors, such as breath holding (apnea), pressure,
swimming activity, temperature, and even cognitive control. However, the
individual effects of these factors on diving heart rate are poorly
understood due to the difficulty of parsing their relative contributions in
diving pinnipeds. Here, we examined the effects of apnea and external
sensory inputs as autonomic drivers of bradycardia. Specifically, we
hypothesized that 1) water stimulation of facial receptors would—as is the
case for terrestrial mammals—enhance the dive response, 2) increasing the
facial area stimulated would lead to a more intense bradycardia, and 3)
cold water would elicit a more pronounced bradycardia than warm water.
Three harbor seals (*Phoca vitulina*) and a California sea lion (*Zalophus
californianus*) were trained to breath-hold in air and with their heads
submerged in a basin with variable water level and temperature. We show
that bradycardia occurs during apnea without immersion. We also demonstrate
that bradycardia is strengthened with both increasing area of facial
submersion and colder water. Thus, we conclude that initiation of the DR in
pinnipeds is more strongly related to breath holding than in terrestrial
mammals, but the degree of the DR is potentiated autonomically via
stimulation of facial mechano- and thermoreceptors upon submergence.



The paper can be found here:

http://jeb.biologists.org/content/early/2018/05/16/jeb.176545



Pdf can be requested by sending me an email:

 jeppekaczmarek at gmail.com



Best wishes
Jeppe Kaczmarek
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