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
Abstract:
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 O2 uptake
per respiration, uptake from the broken-stick model yielded a high correlation
(r2>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:
http://jeb.biologists.org/content/219/13/2066
If you
are unable to download the article, please send a request to
marjoleineroos@gmail.com
Kind
regards,
Marjoleine
Roos and co-authors