[MARMAM] New paper: The significance of respiration timing in the energetics estimates of free-ranging killer whales

Marjoleine Roos marjoleineroos at gmail.com
Mon Jul 11 01:01:14 PDT 2016

Dear all,

We are excited to announce the publication of our new paper in the Journal
of Experimental Biology:

Roos, M.M.H., Wu, G.-M., and Miller, P.J.O. 2016. The significance of
respiration timing in the energetics estimates of free-ranging killer
whales (*Orcinus orca*). Journal of Experimental Biology
219(13): 2066-2077, doi: 10.1242/jeb.137513

Respiration rate has been used as an indicator of metabolic rate and
associated cost of transport (COT) of free-ranging cetaceans, discounting
potential respiration-by-respiration variation in O2 uptake. To investigate
the influence of respiration timing on O2 uptake, we developed a dynamic
model of O2 exchange and storage. Individual respiration events were
revealed from kinematic data from 10 adult Norwegian herring-feeding killer
whales (*Orcinus orca*) recorded with high-resolution tags (DTAGs). We
compared fixed O2 uptake per respiration models with O2 uptake per
respiration estimated through a simple ‘broken-stick’ O2-uptake function,
in which O2 uptake was assumed to be the maximum possible O2 uptake when
stores are depleted or maximum total body O2 store minus existing O2 store
when stores are close to saturated. In contrast to findings assuming fixed O
2 uptake per respiration, uptake from the broken-stick model yielded a high
correlation (*r*2>0.9) between O2 uptake and activity level. Moreover, we
found that respiration intervals increased and became less variable at
higher swimming speeds, possibly to increase O2 uptake efficiency per
respiration. As found in previous studies, COT decreased monotonically
versus speed using the fixed O2 uptake per respiration models. However, the
broken-stick uptake model yielded a curvilinear COT curve with a clear
minimum at typical swimming speeds of 1.7–2.4 m s−1. Our results showed
that respiration-by-respiration variation in O2 uptake is expected to be
significant. And though O2 consumption measurements of COT for free-ranging
cetaceans remain impractical, accounting for the influence of respiration
timing on O2 uptake will lead to more consistent predictions of field
metabolic rates than using respiration rate alone.

The paper is accessible at:

If you are unable to download the article, please send a request to
marjoleineroos at gmail.com

Kind regards,
Marjoleine Roos and co-authors

[image: Inline afbeelding 1]
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