[MARMAM] New publication: Acceleration as an index of energy expenditure in wild fur seals

Tiphaine Jeanniard du Dot dudot at zoology.ubc.ca
Sun Nov 6 19:43:18 PST 2016

Dear colleagues,

I am pleased to announce the publication of a new paper in Functional 
Ecology entitled : 'Accelerometers can measure total and 
activity-specific energy expenditures in free-ranging marine mammals 
only if linked to time-activity budgets'.

1. Energy expenditure is an important component of foraging ecology, but 
is extremely difficult to estimate in free-ranging animals and depends 
on how animals partition their time
between different activities during foraging. Acceleration data have 
emerged as a new way to determine energy expenditure at a fine scale but 
this needs to be tested and validated in wild animals.
2. This study investigated whether vectorial dynamic body acceleration 
(VeDBA) could accurately predict the energy expended by marine predators 
during a full foraging trip. We also
aimed to determine whether the accuracy of predictions of energy 
expenditure derived from acceleration increased when partitioned by 
different types of at-sea activities (i.e. diving, transiting,
resting and surface activities).
3. To do so, we equipped 20 lactating northern (/Callorhinus ursinus/) 
and 20 lactating Antarctic fur seals (/Arctocephalus gazella/) with GPS, 
time-depth recorders and tri-axial accelerometers
and obtained estimates of field metabolic rates using the doubly 
labelled water (DLW) method. VeDBA was derived from tri-axial 
acceleration, and at-sea activities (diving, transiting,
resting and surface activities) were determined using dive depth, 
tri-axial acceleration and travelling speed.
4. We found that VeDBA did not accurately predict the total energy 
expended by fur seals during their full foraging trips (R2 = 036). 
However, the accuracy of VeDBA as a predictor
of total energy expenditure increased significantly when foraging trips 
were partitioned by activity and when activity-specific VeDBA was paired 
with time-activity budgets (R2 = 070).
Activity-specific VeDBA also accurately predicted the energy 
expenditures of each activity independent of each other (R2 > 085).
5. Our study confirms that acceleration is a promising way to estimate 
energy expenditures of free-ranging marine mammals at a fine scale never 
attained before. However, it shows that it
needs to be based on the time-activity budgets that make up foraging 
trips rather than being derived as a single measure of VeDBA applied to 
entire foraging trips. Our activity-based
method provides a cost-effective means to accurately calculate energy 
expenditures of fur seals using acceleration and time-activity budgets, 
that can be transfered to studies on other species.

This article is available at: 

Best wishes,

Tiphaine Jeanniard du Dot, PhD

Tiphaine Jeanniard-du-Dot, PhD
Marine Mammal Research Unit
2202 Main Mall, AERL bldg
University of British Columbia
Vancouver, BC, V6T1Z4, CANADA
Tel:+1-604-822-9150 / cell:+1-604-724-4230

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