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: [email protected] Cheers, Erin
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