[MARMAM] Two new papers on bioenergetics and reproduction in common minke whales

Fredrik denupplyste at hotmail.com
Tue Dec 3 22:49:49 PST 2013



I am pleased to announce the publication
of the following two papers focusing on bioenergetics and reproductive biology
of minke whales in Iceland.

 

 

Paper 1:

 

Christiansen, F., Vikingsson, G.A., Rasmussen, M.
& Lusseau, D. 2013. Minke whales maximise energy storage on their feeding
grounds. Journal of Experimental Biology 216: 427-436.

 

Abstract:

Seasonal
trends in energy storage of the minke whale (Balaenoptera acutorostrata),
a capital breeder, were investigated in Iceland, a North Atlantic feeding
ground. The aim was to better understand the energy acquisition strategies of
minke whales and the energetic costs that different reproductive classes face
during the breeding season. We modelled total blubber volume, using blubber
thickness and morphometric measurements of individual whales. Blubber volume
was influenced by body length, and was higher for pregnant females than mature
whales. Blubber volume increased linearly through the feeding season at the
same rate for mature (mean ± s.e.m.=0.0028±0.00103 m3 day-1;
N=61 male, 5 female) and pregnant whales (0.0024±0.00100 m3 day-1; N=49), suggesting that minke whales aim to
maximise energy storage while on the feeding grounds. The total amount of
blubber accumulated over the feeding season (0.51±0.119 m3 for
mature and 0.43±0.112 m3
for pregnant whales), together with energy stored as muscle and intra-abdominal
fats, constitutes the total amount of energy available for reproduction (fetus
development and lactation) on the breeding grounds, as well as migration, daily
field metabolic rates, growth and body maintenance. No seasonal variation was
observed for immature whales (N=4 male, 12 female), suggesting that they
are investing most of their excess energy into growth rather than reproduction,
in order to reach the length of sexual maturity faster and start reproducing earlier.
Our novel modelling approach provides insight into large whale bioenergetics
and life history strategies, as well as the relationship between single-site
measurement of blubber thickness and total blubber volume.

 

 

 

Paper 2:

 

Christiansen, F., Vikingsson, G.A., Rasmussen, M.
& Lusseau, D. 2013. Female body condition affects foetal growth in a
capital breeding mysticete. Functional
Ecology. doi:10.1111/1365-2435.12200

 

Abstract: 



1. Understanding
how female body condition (FBC) influences foetal development, and hence offspring
production, is fundamental for our understanding of species reproductive
physiology and life history.

 

2. We
investigated the effects of FBC on foetus growth in common minke whales.
Pregnant minke whales were sampled around Iceland during the summer feeding
seasons between 2003 and 2007 and the length and weight of their foetuses were
measured. FBC was modelled as the relative difference between measured blubber
volume and the average expected blubber volume of individual whales.
Generalized linear models were used to test the effect of FBC on foetus length,
while accounting for the daily growth in foetus size through gestation, as well
as other covariates.

 

3. Foetus
length increased curvilinearly through the study period at an average rate of 0.964
cm day-1 (SE =
0.138).
The effect of FBC on foetal length was nonlinear, showing an almost linear
positive relationship for females in poorer body condition (FBC < 0), which levelled off at better body conditions (FBC > 0).

 

4. The
curvilinear relationship between FBC and foetus growth was confirmed by fitting
a generalized additive model and by running separate analyses on two subsets of
data separating females in poorer and better condition.

 

5. Our
findings suggest that females that are in poorer body condition reduce their
energetic investment in their foetus proportionately to their condition, most
likely to help maintain a high survival probability. That foetus length did not
increase for females in better body condition suggests that females have an
upper limit on the amount of energy they will or can invest in their foetus.
Reducing the size at birth by reducing the gestation period is also unlikely, because
the reproductive cycle of balaenopterids is strongly linked to their seasonal
migration between feeding grounds and breeding grounds. This study is the first
to demonstrate that FBC can affect foetus growth in a capital breeding
mysticete.

 

 

 

Please contact me by email for a
copy of these articles if you are interested: f.christiansen at live.se. I will
also be attending the SMM conference next week in New Zealand, and present some
of these results on Wednesday Dec 11 at 09:00 in Castle 2.

 

Best regards,

 

Fredrik
Christiansen

 

Research fellow

Centre for Integrative Ecology

School of Life and Environmental Sciences

Deakin University 

Warrnambool Campus, PO Box 423, Warrnambool, VIC 3280

Phone: +61 3 55633080

Email: f.christiansen at deakin.edu.au, f.christiansen at live.se

Publications: http://scholar.google.com.au/citations?user=vkA5Y3EAAAAJ&hl=en&oi=sra

 

 		 	   		  
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