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The significance of respiration timing in the energetics estimates of free-ranging killer whales

Check out volume 219 issue 13 of the Journal of Experimental Biology for my paper:

The significance of respiration timing in the energetics estimates of free-ranging killer whales (Orcinus orca)

Marjoleine M. H. Roos, Gi-Mick Wu, Patrick J. O. Miller
Journal of Experimental Biology 2016 219: 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 O2exchange 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 O2uptake 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.

 

Also, one of my photos made it on the cover of JEB and the paper was selected for Inside JEB:
Respiration timing is key for estimating cetacean energetics

 

 

Coming soon: Cetacean energetics and respiration paper in Journal of Experimental Biology

Very exciting news: in a couple of weeks the paper I wrote together with Patrick Miller and Mick Wu, both working at SMRU (UK), will be published by the Journal of Experimental Biology. The paper is focusing on the significance of accounting for respiration timing when making estimations on cetaceans’ energetics. This paper is introducing an innovative oxygen model including DTAG data.

To be continued …