[MARMAM] Two new papers on metabolism/energetics of Pacific white-sided dolphins

Erin Rechsteiner erinrechsteiner at gmail.com
Thu Aug 29 15:47:24 PDT 2013


Dear colleagues,

We are pleased to announce the following two papers which have recently
been published.

Rechsteiner EU, Rosen DAS, & Trites AW. Seasonal resting metabolic rate and
food intake of captive Pacific white-sided dolphins (*Lagenorhynchus
obliquidens*). Aquatic Mammals 39(3) 241-252
*
*
*Abstract.** *Like many marine mammals, Pacific white-sided dolphins
(*Lagenorhynchus
obliquidens*) consume prey that change seasonally in numbers, distribution,
and energy density. However, it is not known whether these ecological
factors are associated with underlying seasonal changes in energy
requirements. We investigated these potential seasonal shifts in physiology
by measuring resting metabolic rate (a conserved physiological trait) and
recording associated daily food energy intake of three captive adult
Pacific white-sided dolphins over 12 consecutive months. Two dolphins that
met the criteria for measuring resting metabolism had a mean (± SE) mass-
specific rate of 0.31 ± 0.0047 MJ kg-1 day-1 (~34 MJ day-1), which was
higher than that of other species of small cetaceans. Resting metabolic
rates of Pacific white-sided dolphins did not vary seasonally and, hence,
were not related to observed seasonal changes in water or air temperature,
total energy intake, or body mass. Overall, resting metabolism accounted
for ~70% of total energy intake. However, total food energy intake changed
seasonally and was highest during the fall (October to December). While
levels of food intake were not predicted by resting metabolic rate, body
mass, or water and air temperatures, the increased intake in the fall
resulted in the seasonal increase in body mass exhibited by all three
dolphins. Our estimates of resting metabolic rates and relative changes in
total energy intake can be used to parameterize bioenergetic models needed
to estimate the ecological impacts and energetic requirements of Pacific
white-sided dolphins in the wild, which will have conservation implications.

and

Rechsteiner EU, Rosen DAS, & Trites AW. Energy requirements of Pacific
white-sided dolphins (*Lagenorhynchus obliquidens*) as predicted by a
bioenergetic model. Journal of Mammalogy. 94(4) 820-832

*Abstract. *Apex predators such as Pacific white-sided dolphins
(*Lagenorhynchus
obliquidens*) have the potential to impact prey populations and to be
affected by changes in prey abundance. As abundant predators that range
widely across the North Pacific Ocean, their interactions with prey
populations may have conservation implications. The energy required by
individual Pacific white-sided dolphins was estimated using a bioenergetic
model that accounted for different age classes and reproductive stages
(calf, juvenile, adult, pregnant, and lactating). Monte Carlo simulations
incorporating variability in model parameters (i.e., body mass, growth
rate, costs of gestation and lactation, metabolic rate, cost of activity,
and assimilation efficiencies) were used to predict ranges in energetic
requirements of this species. Mean (*+* SD) total energy requirements in
MJ/day were 40.3 *+* 6.2 for calves, 70.8 *+* 8.2 for juveniles, 69.0 *+* 3.6
for adults, 70.3 *+* 3.6 for pregnant females, and 98.4 *+* 20.0 for
lactating females. Estimates of energy requirements were most sensitive to
uncertainty in values used for resting metabolic rates and energetic costs
of activity. Estimated mass-specific energy requirements in MJ kg -1
day -1 were
elevated in calves (1.55 *+* 0.23), juveniles (0.97 *+* 0.11), and
lactating females (1.01 *+* 0.21) when compared with non-reproductive
adults and pregnant females (~0.71 *+* 0.04). Based on a high-energy diet,
an average-sized dolphin (78 kg) would consume approximately 12.5–15.8 kg
of fish or 16–20% of its body mass per day. These high energetic
requirements may indicate a reliance of dolphins on energy-rich prey, which
has implications for fisheries management and conservation of marine
mammals.

Both articles are available online on the journal websites (Aquatic
Mammals, Journal of Mammalogy).

For a PDF copy of either paper please contact the corresponding author Erin
Rechsteiner at: e.rechsteiner at fisheries.ubc.ca

Cheers,

Erin
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