Distribution and diving behaviour of crabeater seals (Lobodon carcinophagus) off Queen Maud Land

Eight crabeater seals (Lobodon carcinophagus) (three females, five males), ranging in body mass between 125 and 220 kg, were captured off Queen Maud Land (70–72°S, 7–16°W) during the last week of February, just after moulting, and tagged with Argos satellite-linked dive recorders to provide data on location and diving depth and duration. During the first few weeks of March the seals were moving in the pack ice along the continental shelf edge, close to the coast of Queen Maud Land. In April and May, when the pack ice extended northwards, most of the seals moved north, one reaching 63°S in late May. In the first half of June the two remaining seals turned south and moved back deep into the pack ice. The seals made about 150 dives per day each throughout the study period. Ninety percent of these were made to depths of less than 52 m. Individual maximum diving depths varied between 288 and 528 m. In March the seals were most active at night, when the dive depth was shallower than during the day. In April and May the seals were more active during day-time, with an absence of any diurnal change in divng depth. These results support the notion that crabeater seals predominantly feed on krill in Antarctic pack ice, even when winter returns to the waters off Queen Maud Land.Publication no. 134 of the Norwegian Antarctic Research Expedtion 1992/1993     

Body mass loss of moulting female southern elephant seals,Mirounga leonina,at Macquarie Island

Thirteen female southern elephant seals moulting at Macquarie Island lost an average of 4.46±0.80 kg/day (10.01±1.20g/kg/day). There was no significant difference between this rate of body mass loss and that reported for moulting female southern elephant seals from South Georgia. Moulting female southern elephant seals however exhibited larger mass specific mass loss than either female northern elephant seals or male southern elephant seals, indicating a higher metabolic cost of moult in these animals.     

Temperature regulation in a burrow-nesting tropical seabird,the Wedge-tailed Shearwater (Puffinus pacificus)

Summary At low air temperatures (2.3–13.9°C), Wedge-tailed Shearwaters (Puffinus pacificus) shivered and their oxygen consumption increased to as much as 283% of the mean value (0.77 ml O₂/g·h) within the thermoneutral zone of air temperature (23–34°C). The minimal thermal conductance of the tissues and plumage was similar to the value predicted from the body mass (320.5 g). The oxygen consumption of the birds within their thermoneutral zone was lower than predictions based on body mass. At elevated air temperatures, the shearwaters panted at respiratory frequencies as high as 260 respirations/min; maximal respiratory frequencies were not invoked until the birds had become hyperthermic. During exposure to a hot environment, the oxygen consumption of the birds increased and in most instances the shearwaters were not able to lose heat equivalent to their concurrent metabolic heat production.Symbols and abbreviations BMR basal metabolic rate - C _total total thermal conductance - f respiratory frequency - TEWL total evaporative water loss - T _st stomach temperature - T _re rectal temperature     

Distribution and abundance of spotted seals Phoca largha and ribbon seals Phoca fasciata in the southern Sea of Okhotsk

The distribution and abundance of spotted seals (Phoca largha) and ribbon seals (Phoca fasciata) were assessed in March and April, 2000, by aerial line-transect surveys along the southern edge of the pack ice off the coast of Hokkaido (southern Sea of Okhotsk), Japan. Five hundred and seventeen spotted seals and 107 ribbon seals were found on the total 2944 km survey line. Total abundance was estimated to be 13 653 spotted (95% CI = 6167–30 252) and 2260 ribbon seals (95% CI = 783–6607) in March, and 6545 spotted (95% CI = 3284–815 644) and 3134 ribbon seals (95% CI = 1247–17 802 512) in April. The pack ice area off Hokkaido had higher densities (0.54 seals km^–2 and 0.58 seals km^–2 in March and April, respectively) of spotted seals than those reported in eastern Sakhalin, whereas densities (0.09 seals km^–2 in March and 0.28 seals km^–2 in April) of ribbon seals were lower than those in eastern Sakhalin. The large number of spotted seal pups suggests that the study area is an important breeding center. A greater number of female spotted seals with pups tended to be found in the center of larger and rougher floes than in other categories, and they were more abundant in stable pack ice areas. Observations of ribbon seals were limited because the survey period preceded the peak of pupping season. Ribbon seal surveys were also hampered by the inability to fly over the main breeding area between the Shiretoko Peninsula and Kunashiri Island.     

Ventilatory physiology of the numbat (<Emphasis Type="Italic">Myrmecobius fasciatus</Emphasis>)

This study examines the ventilatory physiology of the numbat (Myrmecobius fasciatus), a small to medium-sized (550 g) termitivorous marsupial. Ventilatory parameters at thermoneutrality reflect the slightly low (83% of predicted) basal metabolic rate of the numbat, with ventilation frequency (ƒ_R; 30.6±3.65 breaths min^–1), tidal volume [V_T; 6.0±0.66 ml at body temperature and pressure, saturated (BTPS)] and consequently minute volume (V_I; 117.7±15.22 ml min^–1; BTPS) all being 80–87% of that expected for a marsupial of similar body mass. Oxygen extraction was 27.7±1.37% in the thermoneutral zone. As is typical of marsupials, numbats accommodated increased oxygen consumption rates at ambient temperatures (T _a) below the thermoneutral zone by increasing minute volume (up to 411.2±43.98 ml min^–1; BTPS at T _a=10 °C) rather than oxygen extraction. Minute volume at 10 °C increased more by changes in ventilation frequency (up to 45.5±4.85 breaths min^–1) than tidal volume (9.4±1.03 ml, BTPS), as is also typical for a small-medium sized marsupial.Abbreviations BMR basal metabolic rate - BTPS body temperature and pressure, saturated - EO ₂ oxygen extraction - ƒ _R ventilation frequency - STPD standard temperature and pressure, dry - T _a ambient temperature - T _b body temperature - TNZ thermoneutral zone - V _I minute volume - V _T tidal volume - O ₂ oxygen consumption rate Communicated by I.D. Hume     

Protein and lipid utilization during fasting with shallow and deep hypothermia in the European hedgehog (Erinaceus europaeus)

We investigated whether the relative contributions of body protein and lipid reserves differ according to the level of energy expenditure in fasting animals. Protein and lipid utilization was therefore quantified and compared in hedgehogs which fasted with shallow and deep hypothermia, i.e. by exposure at 5 or 20 °C ambient temperature. Body composition was determined for every 150-g decrease in mass throughout the experiment, allowing the calculation of regression lines between body mass (independent variable, x) and body composition (dependent variable, y: water, protein, neutral lipids, phospholipids and cholesterol). There were highly significant (P<0.001) linear decreases in all body components with decreasing body mass in both groups of hedgehogs. Neutral lipids were the main component of the total body mass loss (54%) in fasted animals with shallow and deep hypothermia, percentages of water (26–30%) and protein (10–11%) being lower, and those of phospholipid and cholesterol negligible (<0.5%). In spite of different levels in energy expenditure (2.54 and 1.07 W·kg^-1 in shallow-and deep-hypothermal fasting hedgehogs, respectively), the energy sources were identical in both groups, neutral lipid being the main fuel (91–92%) and body protein accounting for the remainder (8–9%). Prolonged fasting with shallow and deep hypothermia were marked by low alaninemia and glycemia, while plasma free fatty acids and -hydroxybutyrate were elevated. These data therefore indicate that the relative contribution of lipid and protein is similar during prolonged fasting with shallow and deep hypothermia, i.e. there is no specific effect of deep hypothermia on body fuel utilization. The tolerance of a much longer fast in deep-hypothermal hedgehogs can simply be attributed to the lower rates of lipid and protein utilization as a result of the lower level of energy expenditure.Abbreviations bm body mass     

Water exchange between the pregnant ewe,the foetus and its amniotic and allantoic fluids

Water exchange between the ewe and its foetus was measured in two Merino ewes maintained with continuous feeding under thermoneutral conditions from about day 90 of gestation to term. Catheters were established in the maternal pulmonary artery (MPA), the foetal dorsal aorta (FDA) and the amniotic and allantoic sacs. Doses of tritiated water were given into either the MPA or the FDA on five occasions, three for one ewe and two for the other, at least 6 days apart and samples were taken from all catheters for 31 h following the dose. An open, eight-compartment restricted model was developed which simultaneously fitted the tracer data and the ewes water balance, determined by measurement and calculation. The ewes delivered live lambs at term. Water was exchanged between ewe and foetus at 16–43 l h^–1 whereas net flow to the foetus averaged 82 ml day^–1. Turnover times were 20–39 min in the ewes body water, 2–7 min in foetal body water, 10–58 min in amniotic water and 3–22 min in allantoic water; the whole-body half-times were 4.5–5.7 days. The data suggest that intramembranous exchange was the major contributor to water exchange in amniotic and allantoic fluids. The mean residence time of water in the rumen (39–52 min) was shorter than in non-pregnant sheep, suggesting that blood flow to the rumen increased during mid to late gestation.     

Bioenergetics and thermal physiology of American water shrews (<Emphasis Type="Italic">Sorex palustris</Emphasis>)

Rates of O₂ consumption and CO₂ production, telemetered body temperature (T_b) and activity level were recorded from adult and subadult water shrews (Sorex palustris) over an air temperature (T_a) range of 3–32°C. Digesta passage rate trials were conducted before metabolic testing to estimate the minimum fasting time required for water shrews to achieve a postabsorptive state. Of the 228 metabolic trials conducted on 15 water shrews, 146 (64%) were discarded because the criteria for inactivity were not met. Abdominal T_b of S. palustris was independent of T_a and averaged 38.64±0.07°C. The thermoneutral zone extended from 21.2°C to at least 32°C. Our estimate of the basal metabolic rate for resting, postabsorptive water shrews (96.88±2.93 J g^–1 h^–1 or 4.84±0.14 ml O₂ g^–1 h^–1) was three times the mass-predicted value, while their minimum thermal conductance in air (0.282±0.013 ml O₂ g^–1 h^–1) concurred with allometric predictions. The mean digesta throughput time of water shrews fed mealworms (Tenebrio molitor) or ground meat was 50–55 min. The digestibility coefficients for metabolizable energy (ME) of water shrews fed stickleback minnows (Culaea inconstans) and dragonfly nymphs (Anax spp. and Libellula spp.) were 85.4±1.3% and 82.8±1.1%, respectively. The average metabolic rate (AMR) calculated from the gas exchange of six water shrews at 19–22°C (208.0±17.0 J g^–1 h^–1) was nearly identical to the estimate of energy intake (202.9±12.9 J g^–1 h^–1) measured for these same animals during digestibility trials (20°C). Based on 24-h activity trials and our derived ME coefficients, the minimum daily energy requirement of an adult (14.4 g) water shrew at T_a = 20°C is 54.0 kJ, or the energetic equivalent of 14.7 stickleback minnows.     

Fluoride content of Antarctic marine animals caught off Elephant Island

Summary A number of marine animals were collected off Elephant Island (South Shetland Islands) and analyzed for fluoride (mg/kg wet weight). In fish muscle from six Antarctic species the content was low (approx. 2) not exceeding the content of fishes from other waters. In bone-tissue a concentration of 616–1207 was found. In some benthic living animals the amount of fluoride (determined in the whole body) was different depending on the species investigated. Low amounts of approx. 10 were encountered in a pycnogonid, an octopodid and a polychaet. Very high values of 200–600 were determined in isopods, amphipods, ophiuroids and asteroids, these concentrations exceeded sometimes the value found in Antarctic krill.Results of the Antarctic Expedition 1981 of the Federal Republic of Germany with FRV Walther Herwig     

Effects of 12 weeks of aerobic exercise plus dietary restriction on body composition, resting energy expenditure and aerobic fitness in mildly obese middle-aged women

This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The subjects were randomly assigned to exercise/diet (n = 17) or control (n = 15) groups. The exercise/diet group participated in an aerobic training programme, 45–60 min · day ^–1 at 50%–60% of maximal oxygen uptake (VO_2max), 3–4 days · week^–1, and also adopted a self-regulated energy deficit relative to predicted energy requirements (–1.05 MJ · day ^–1 to –1.14 MJ · day ^–1 ). After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (m _ff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of m _ff (4%). The increase in RMR/m _ff was not correlated with any increase in VO_2max/m _ff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.     

Freeze or dehydrate: only two options for the survival of subzero temperatures in the arctic enchytraeid<Emphasis Type="Italic"> Fridericia ratzeli</Emphasis>

Hygrophilic soil animals, like enchytraeids, overwintering in frozen soil are unlikely to base their cold tolerance on supercooling of body fluids. It seems more likely that they will either freeze due to inoculative freezing, or dehydrate and adjust their body fluid melting point to ambient temperature as has been shown for earthworm cocoons and Collembola. In the present study we tested this hypothesis by exposing field-collected adult Fridericia ratzeli from Disko, West Greenland, to freezing temperatures under various moisture regimes. When cooled at –1 °C min^–1 under dry conditions F. ratzeli had a mean temperature of crystallisation (T_c) of –5.8 °C. However, when exposed to temperatures above standard T_c for 22 h, at –4 °C, most individuals (90%, n= 30) remained unfrozen. Slow cooling from –1 °C to –6 °C in vials where the air was in equilibrium with the vapour pressure of ice resulted in freezing in about 65% of the individuals. These individuals maintained a normal body water content of 2.7–3.0 mg mg^–1 dry weight and had body fluid melting points of about –0.5 °C with little or no change due to freezing. About 35% of the individuals dehydrated drastically to below 1.1 mg mg^–1 dry weight at –6 °C, and consequently had lowered their body fluid melting point to ca. –6 °C at this time. Survival was high in both frozen and dehydrated animals at –6 °C, about 60%. Approximately 25% of the animals (both frozen and dehydrated individuals) had elevated glucose concentrations, but the mean glucose concentration was not increased to any great extent in any group due to cold exposure. The desiccating potential of ice was simulated using aqueous NaCl solutions at 0 °C. Water loss and survival in this experiment were in good agreement with results from freezing experiments. The influence of soil moisture on survival and tendency to dehydrate was also evaluated. However, soil moisture ranging between 0.74 g g^–1 and 1.15 g g^–1 dry soil did not result in any significant differences in survival or frequency of dehydrated animals even though the apparent wetness and structure of the soil was clearly different in these moisture contents.Abbreviations DW dry weight - FW fresh weight - MP melting point - RH relative humidity - Tc crystallisation temperatures - WC water contentCommunicated by I.D. Hume     

Responses of aerial ventilation to hypoxia and hypercapnia inChanna argus,an air-breathing fish

Summary The snake-head fish (Channa argus) is an obligate air-breather inhabiting fresh waters in the temperate zone of East Asia.Ventilation of the air-breathing organ and aerial gas exchange were measured in 1 to 2 kg specimens at 15 and 25°C. Additionally, the ventilatory responses to hypoxia and hypercapnia were studied. Aerial ventilation increased from 1.1 to 2.9 mlbtps·kg^–1·min^–1 when temperature rose from 15 to 25°C. Concomitantly, O₂-uptake through airbreathing increased from 0.1 mlstpd·kg^–1·min^–1 (15°C) to 0.28 mlstpd·kg^–1·min^–1 (25°C), whereas aerial gas exchange was less important for CO₂-climination as evident from low gas exchange ratios (0.16 at 15°C, 0.29 at 25°C).Ventilation increases only slightly in response to inspiration of hypercapnic gas mixtures or to hypoxic conditions in water. By contrast, inspiration of hypoxic gas mixtures caused marked increases of ventilation in particular at the higher temperature.Aerial ventilation inChanna is low compared to values for ectothermic pulmonary breathers. However, its ventilatory responses to hypoxia strikingly resemble those of reptiles: The most marked ventilatory response to hypoxia occurs at the higher temperature where the demands for O₂ are greatest.     

Recovery of Norway spruce (Picea abies) seedlings from repeated drought as affected by boron nutrition

The effects of two boron (B) levels on growth, shoot water potential, gas exchange and nutrient accumulation in Norway spruce [Picea abies (L.) Karst.] seedlings were studied in a growth room experiment lasting 22 weeks which included well-watered control seedlings and seedlings exposed to one (8 days) or two (6+8 days) periods of drought and a rewatering period (8 days) at the end of the experiment. The effects of B and drought were monitored during drought and recovery. Needle B concentrations were 6 mg kg^–1 (–B treatment) and 34 mg kg^–1 (+B treatment) at the end of the experiment. The –B seedlings showed visible symptoms of damage in the upper shoot after repeated drought and had reduced height growth, root dry mass, allocation of biomass to roots and formation of root tips and mycorrhizas and reduced needle P, Ca, and Mg concentrations and contents. In contrast, ¹⁵N uptake, shoot water potential and gas exchange were not markedly affected by B. It can be concluded that the visible symptoms of damage at low B were probably related to reduced B transport due to repeated drought. In contrast, the effects of low B on growth, particularly of the roots, and on nutrient uptake can be regarded as early effects which occur before any influence on shoot water potential or gas exchange. The positive effects of B on root biomass and nutrient accumulation are of particular importance regarding the establishment of young seedlings in the field.     

Feeding rates and energy deficits of juvenile and adult Japanese monkeys in a cool temperate area with snow coverage

Japanese monkeys, Macaca fuscata, living in a cool temperate forest experienced energy crises in winter. We measured feeding times and feeding rates (mass of foods eaten per unit time of feeding) in six different-sized, age–sex classes (1.2–12.6 kg body mass) in autumn and winter. One-, 2- and 3~4-year-olds spent 34–35% and 44–46% of the day feeding in autumn and winter, respectively. Monkeys less than 0 years old spent less time feeding (16–28%) than average in winter and autumn; adult females spent less (41%) in winter; and adult males spent less (25%) in autumn. All age–sex classes ate mainly fruits in autumn and the heavier classes fed more on tree bark than buds in winter. The feeding rate for fruits (2.3–53.5 g min^–1) was nine to 12 times faster than those for buds (1.0– 4.8 g min^–1) and bark (0.5–4.4 g min^–1), and energy content did not differ among fruits (22.1 kJ g^–1 dry mass), buds (19.9 kJ g^–1 dry mass) and bark (23.2 kJ g^–1 dry mass). Energy base feeding rates increased with body mass where the body mass exponent for buds (0.29) was smaller than those for bark (0.64) and fruits (0.63), which might be attributable to the unit size of food items and mass dependency of masticatory apparatus. Our monkeys obtained two to five times more energy in autumn (1567–1150 kJ day^–1) than in winter (604–3020 kJ day^–1). Adult females obtained 60% of expected energy expenditure and other classes obtained 77–88% of that in winter.     

Growth and population parameters of the world’s northernmost harbour seals Phoca vitulina residing in Svalbard, Norway

The harbour seals (Phoca vitulina) in Svalbard are the northernmost population of this species. The population size is thought to be less than 1,000 individuals; these animals reside principally within a national park on Prins Karls Forland on the west coast of Spitsbergen, Svalbard, at about 78°20N. The material presented in this study was collected from 367 live-captured animals, aged based on growth layers read from stained, decalcified incisor sections (except for pups of the year). Standard length (F_1,246=45.70, P<0.0001) and body mass (F_1,258=25.28; P<0.0001) were both significantly influenced by sex when age was taken into account. Adult males are both longer [152.9±4.8 (SE) vs 140.1±2.0 cm, standard length] and heavier (104.0±5.0 vs 83.2±2.7 kg, body mass) than adult females in this population. Age at sexual maturity was assessed based on analyses of sex hormones. Testosterone levels in males showed an abrupt increase at 6 years of age, while estradiol levels in females increased from age 4. The reproductive rate of adult females was 0.93. The longevity of Svalbard harbour seals was short compared to harbour-seal populations from other areas. However, these seals are not exposed to terrestrial predation; there is no known mortality due to fisheries or hunting and their pollution burdens are low. Extreme seasonality and perhaps other harsh environmental conditions at the northern edge of this species distribution may exert long-term low levels of stress that result in short life span, or there are currently unknown acute sources of mortality in this population. To our knowledge, this is the first study of population parameters on a pinniped species using cross-sectional, non-terminal sampling.     

Energy requirements of the red kangaroo (<Emphasis Type="Italic">Macropus rufus</Emphasis>): impacts of age,growth and body size in a large desert-dwelling herbivore.

Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo (Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5–1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641±27 kJ kg^–0.75 day^–1 and 677±26 kJ kg^–0.75 day^–1, respectively, significantly higher than the 385±37 kJ kg^–0.75 day^–1 ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg^–0.75 day^–1 and 390 kJ kg^–0.75 day^–1 digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220–400 days) had average growth rates of 55 g body mass day^–1. At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7–1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g^–1, within the range found for most young growing mammals.Abbreviations BMR basal metabolic rate - DEI digestible energy intake - MER maintenance energy requirement - MER_g maintenance plus growth energy requirement - PPE permanent pouch exit - RMR resting metabolic rate - YAF young-at-foot Communicated by I.D. Hume     

Digesta passage and functional anatomy of the digestive tract in the desert tortoise (Xerobates agassizii)

The herbivorous tortoise Xerobates agassizii contents with large fluctuations in the quality and abundance of desert pastures. Responses to grass (Schismus barbatus), herbage (Sphaeralcea ambigua) and pelleted diets were studied in captive animals. Digestive anatomy was investigated in wild tortoises. Cornified esophageal epithelia and numerous mucus glands along the digestive tract indicated a resistance to abrasive diets. Gastric contents were acidic whereas hindgut digesta were near neutral pH. The colon was the primary site of fermentation with short-chain fatty acids mainly comprised of acetate (69–84%), propionate (10–15%) and n-butyrate (1–12%). Fibre digestion was extensive and equivalent to 22–64% of digestible energy intakes. Large particles of grass (25 mm Crmordants) were excreted as a pulse but retained longer than either fluids (Co-EDTA) or fine particles (2 mm; Yb). Patterns of marker excretion suggested irregular mixing of only the fluid and fine particulate digesta in the stomach and the colon. Mean retention times of Crmordants were 14.2–14.8 days on the grass and highfibre pellets. Intakes of grass were low and accompanied by smaller estimates of digesta fill than for the high-fibre pellets. Digestive capacity was large and estimated at 11–21% of body mass on these diets. The capacious but simple digestive anatomy of the tortoise may provide the greatest flexibility in utilizing a variety of forages in its unreliable habitat.Abbreviations bm body mass - DM drymatter - EDTA ethylene-diamine tetra-acetic acid - MRT mean retention time - NDF neutral detergent fibre - SCFA short-chain fatty acid(s) - T _max time to maximum marker concentration     

Digestion and energy metabolism in a small arboreal marsupial,the Greater Glider (Petauroides volans), fed high-terpeneEucalyptus foliage

Summary The digestion and metabolism ofEucalyptus radiata foliage was studied in a small (1–1.5 kg) arboreal marsupial, the greater glider (Petauroides volans). Mean dry matter intake was 44 g·kg^–0.75·d^–1 and mean cell wall digestibility was 34%; these values fall within the range of other marsupials fedEucalyptus foliage. Digestible energy content ofE. radiata was high compared to other eucalypts because of the high content and digestibility of essential oils. However, excretion of essential oils and their metabolites in the urine meant that greater gliders retained only 55% of their digestible energy intakes (0.61 MJ · kg^–0.75· d^–1) as metabolizable energy (ME). Low ME intakes were not offset by low standard metabolic rates (2.39 W · kg^–0.75), but the efficiency with which ME substituted for tissue energy was high (94%), so that greater gliders were able to maintain energy balance and body mass onE. radiata foliage.Abbreviations ME metabolizable energy - DE digestible energy - RQ respiratory quotient - FHP fasting heat production     

Implications of element deficits for zooplankton growth

Daily measurements of mass and phosphorus (P) were made for Daphnia magna feeding on a high concentration (1 mg C l^–1) of P-sufficient (molar C:P = 70–80, `P+') or P-deficient (C:P = 1000, `P–') green algae (Scenedesmus obliquus or Ankistrodesmus falcatus). Animals feeding on P+ algae for 12 d showed a sharp decline in growth during the last juvenile instar (mean ± SE from 0.57 ± 0.02 to 0.25 ± 0.03 d^–1) and a modest decline in P-content at the first adult instar (from 1.55 ± 0.01 to 1.46 ± 0.02% mass). Animals feeding on P– algae showed declines in P-content to as low as 0.84% after 5 d, with the sharpest decline in the first day. Growth of animals feeding on P– algae declined sharply over time and showed a linear relationship with the grazer's P-content. Growth during the first day of exposure to P– algae was relatively high (mean 0.39 ± 0.03 d^–1) but approached zero as P-content declined to <0.90% mass. For animals feeding on P+ algae, the ontogenetic decline in P-content resulted in only a small difference between growth calculated for mass and growth calculated for Daphnia P. In contrast, for animals feeding for 4 d on P– algae, growth calculated for mass was 2–5 times higher than growth based on P. Thus, this study shows that short-term growth assays may substantially underestimate the negative impact of P-deficient resources, unless the decline in the grazer's P-content is taken into account. In this situation, measurement of growth in terms of nutrient content (e.g. grazer's P-content) should provide a better indication of the potential for sustained growth than calculations based on change in mass. This study also supports the `integration of growth' hypothesis (Sterner & Schwalbach, 2001), in which animals undergoing diel migration between water layers with P-deficient and P-sufficient resources experience a reduced growth penalty.     

Evaluation of anesthetic protocol for the collection of semen from captive collared peccaries (Tayassu tajacu) by electroejaculation

The objective of this study is to verify and compare the effects of acepromazine–tiletamine–zolazepam and propofol used in anesthetic protocols for semen collection by electroejaculation from captive collared peccaries. Ten sexually mature animals were physically restrained and anesthetized by either intravenous administration of tiletamine–zolazepam (2 mg/kg) after acepromazine premedication, or a propofol dose of 5 mg/kg. The onset of anesthetic recovery was determined by the animals regaining consciousness and attempting to stand. Semen was collected by electroejaculation and evaluated for volume, pH, sperm concentration, progressive motility, morphology, percentage of live cells and functional membrane integrity. Six anesthetized animals with the acepromazine–tiletamine–zolazepam protocol showed erection, but semen could be collected in only four (40%) attempts. Of the animals anesthetized using propofol, nine showed erection, and the ejaculates were collected in eight (80%) attempts. Furthermore, propofol afforded rapid recovery of animals, and ejaculates with enhanced sperm motility and functional membrane integrity as compared with those collected by the other protocol (P < 0.05). In conclusion, use of propofol for anesthetic restraint of collared peccaries enhanced collection of semen by electroejaculation.