The effect of feeding on the metabolic rate in harbour seals (Phoca vitulina).

The heat increment of feeding was estimated in harbour seals (Phoca vitulina). Seals were given different amounts of herring, ranging from 0.8 to 2.65 kg. The caloric content of the herring ranged from 6575 to 12560 kJ.kg-1 depending on time of year. Metabolic rate increased within 30 min after feeding, and the magnitude and duration of heat increment of feeding depended on the size of the meal and the caloric content of the herring. Measured heat increment of feeding was up to 14.9% of gross energy intake and metabolic rate increased as much as 46% above resting, postabsorptive metabolic rate for 15 h duration in a harbour seal with a body weight of approximately 40 kg.

Resting oxygen consumption in rats during food restriction, starvation and refeeding.

Oxygen consumption was measured in male rats during starvation and during different regimens of restricted feeding and refeeding after starvation. Changes in oxygen consumption and body mass were mostly parallel, but rats with a very reduced food intake displayed the same reduction in oxygen consumption as starved rats, despite the smaller reduction in body mass. Also, rats fed different amounts of food after starvation had different oxygen consumptions, but displayed the same changes in body mass. Two different refeeding regimens with restricted food amounts either induced a further depression of oxygen consumption (i.e. below starvation oxygen consumption), or a stabilizing of oxygen consumption on the level of starvation. The changes in oxygen consumption during restriction and feeding after starvation indicate that reductions in resting metabolic rate may not always be predicted from either body mass change or food intake.

Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters.

Residue levels of the chlorinated hydrocarbons polychlorinated biphenyls (PCBs), total DDT, alpha-, beta- and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and oxychlordane in blubber, and the elements mercury, cadmium, copper, selenium, arsenic, and zinc in liver, of 82 harbour seals, Phoca vitulina, were determined. The seals were found dead or dying in Norwegian waters during the disease outbreak caused by a morbilli virus in 1988. Of the chlorinated hydrocarbons, the highest concentrations were found of PCBs, which were 2-4 times higher than the total DDT concentrations. P,p'-DDE was the main contributor to the total DDT, and constituted about 80%. The PCB and total DDT concentrations ranged from 0.4-38 and 0.1-8.8 mg kg(-1), respectively. The mercury concentrations ranged from 0.1-89 mg kg(-1). Significantly higher mean levels of PCBs (13 mg kg(-1) and mercury (16 mg kg(-1)) were found in blubber and liver, respectively, of seals from the Southern coast of Norway, as compared to the corresponding mean levels in seals from the Oslofjord (8.8 and 4.1 mg kg(-1)), and at the Northwestern coast (5.8 and 7.9 mg kg(-1)), respectively. A significant positive correlation was found between the concentrations of selenium and mercury. When the seals were grouped according to sex and age, females of ageclass > 1 and pups of both sexes had significantly lower PCB and total DDT levels than males ageclass > 1. Significantly higher hepatic mercury levels were found in seals ageclass > 1 as compared to pups. Only low levels of the other organochlorines, cadmium and arsenic, were found. Copper and zinc were considered to be present at normal physiological levels. The present organochlorine and heavy metal concentrations gave no support to suggestions that organochlorines and heavy metal pollution may be directly involved in the observed seal deaths.

Metabolic depression and heat balance in starving Wistar rats.

Resting metabolic rate and heat balance was studied in rats starved for 8 days at ambient temperature 22 degrees C and 30 degrees C. A depression of the resting metabolic rate was observed, at both temperatures. Metabolic rate depression, expressed as a function of the ratio between the real body wt and the normal body wt, was less at 22 degrees C than at 30 degrees C. Deep body temperature decrements of 2 degrees C and 0.6 degrees C by the end of starvation indicated that central temperature controlling mechanisms were affected. Concurrent decrements of evaporative heat loss did not account for the changes in heat conductance, thus indicating that a reduction of peripheral blood circulation also took part.

Weight loss and catabolic adaptations to starvation in grey seal pups.

Five grey seal pups lost from 18 to 32% of their initial body weight during a 21 day starvation period. Blubber fat mass density was 0.93 +/- 0.03 g/cm3. A considerable loss of blubber fat was recorded, but analysis of the weight loss and body size data indicated that blubber fat was retained for thermoregulatory reasons, particularly in the lean, smaller seals. It is possible that phocid seals during periods of negative energy balance have a higher rate of protein catabolism than normal for terrestrial mammals.