Temperature effects on locomotor activity rates of sub-Antarctic oribatid mites

The influence of temperature on locomotor activity was determined for the sub-Antarctic mites, Halozetes fulvus Engelbrecht and Podacarus auberti Grandjean. In both species walking was severely impaired at below-freezing temperatures. Above zero, locomotor activity rates increased with a rise in temperature over a wide temperature range (for example, this was 2–30°C for H. fulvus), and they showed a biologically normal level of sensitivity to change in temperature. All the calculated Q₁₀ values for mean rates over 5° intervals varied between 1.3 and 2.9. The present data are compared with some rate functions of maritime and continental Antarctic micro-arthropods, and they confirm the relative enhancement of the physiological rate by a continental Antarctic mite. One explanation for the less temperature-sensitive rates in H. fulvus and P. auberti may be that they have relatively more time available for normal biological activity.     

C3 photosynthesis and high temperature acclimation of CAM in opuntia basilaris engelm. and bigel

Summary Carbon fixation by CAM at high night temperatures was examined in the stem succulent, Opuntia basilaris. Nighttime accumulation of titratable acids was uniformly high among plants growing naturally along an altitudinal temperature gradient in Death Valley, California during the hot summer period. Plants grown at high temperature regimes (40°/30°C) had rates of CAM and C₃ fixation similar to rates observed in plants maintained at a cool temperature (20°/10°C). C₃ fixation comprised 30% of the total carbon fixed by the potted, well watered plants. However, when pads were excised, C₃ fixation was suppressed while CAM continued unabated.     

Reduction of metabolic rate and thermoregulation during daily torpor

Physiological mechanisms causing reduction of metabolic rate during torpor in heterothermic endotherms are controversial. The original view that metabolic rate is reduced below the basal metabolic rate because the lowered body temperature reduces tissue metabolism has been challenged by a recent hypothesis which claims that metabolic rate during torpor is actively downregulated and is a function of the differential between body temperature and ambient temperature, rather than body temperature per se. In the present study, both the steady-state metabolic rate and body temperature of torpid stripe-faced dunnarts, Sminthopsis macroura (Dasyuridae: Marsupialia), showed two clearly different phases in response to change of air temperature. At air temperatures between 14 and 30°C, metabolic rate and body temperature decreased with air temperature, and metabolic rate showed an exponential relationship with body temperature (r ²=0.74). The Q ₁₀ for metabolic rate was between 2 and 3 over the body temperature range of 16 to 32°C. The difference between body temperature and air temperature over this temperature range did not change significantly, and the metabolic rate was not related to the difference between body temperature and air temperature (P=0.35). However, the apparent conductance decreased with air temperature. At air temperatures below 14°C, metabolic rate increased linearly with the decrease of air temperature (r ²=0.58) and body temperature was maintained above 16°C, largely independent of air temperature. Over this air temperature range, metabolic rate was positively correlated with the difference between body temperature and air temperature (r ²=0.61). Nevertheless, the Q ₁₀ for metabolic rate between normothermic and torpid thermoregulating animals at the same air temperature was also in the range of 2–3. These results suggest that over the air temperature range in which body temperature of S. macroura was not metabolically defended, metabolic rate during daily torpor was largely a function of body temperature. At air temperatures below 14°C, at which the torpid animals showed an increase of metabolic rate to regulate body temperature, the negative relationship between metabolic rate and air temperature was a function of the differential between body temperature and air temperature as during normothermia. However, even in thermoregulating animals, the reduction of metabolic rate from normothermia to torpor at a given air temperature can also be explained by temperature effects.Abbreviations BM body mass - BMR basal metabolic rate - C apparent conductance - MR metabolic rate - RMR resting metabolic rate - RQ respiratory quotient - T _a air temperature - T _b body temperature - T _lc lower critical temperature - T _tc critical air temperature during torpor - TMR metabolic rate during torpor - TNZ thermoneutral zone - T difference between body temperature and air temperature - VO₂ rate of oxygen consumption     

The physiological ecology of Mytilus californianus Conrad

Summary The rates of oxygen consumption, filtration and ammonia excretion by Mytilus californianus have been related to body size and to ration. The rate of oxygen consumption (VO₂) by individuals while immersed, measured on the shore, resembled rates recorded for mussels starved in the laboratory. VO₂ by M. californianus was relatively independent of change in temperature, with a Q ₁₀ (13–22° C) of 1.20. In contrast, the frequency of heart beat was more completely temperature dependent [Q ₁₀ (13–22° C)=2.10]. Filtration rate showed intermediate dependence on temperature change [Q ₁₀ (13–22° C)=1.49] up to 22° C, but declined at 26° C. Both VO₂ and filtration rate declined during starvation. The utilisation efficiency for oxygen was low (approx. 4%) between 13 and 22° C, but increased to 10% at 26° C. Three components of the routine rate of oxygen consumption are recognised and estimated; viz. a basal rate (0.136 ml O₂ h^-1 for a mussel of 1 g dry flesh weight), a physiological cost of feeding (which represented about 6% of the calories in the ingested ration), and a mechanical cost of feeding which was three times higher than the physiological cost. The ratio oxygen consumed to ammonia-nitrogen excreted was low, and it declined during starvation. These data are compared with previously published measurements on Mytilus edulis, and the two species of mussel are shown to be similar in some of their physiological characteristics, though possibly differing in their capacities to compensate for change in temperature. For M. californianus, the scope for growth was highest at 17–22° C and declined at 26° C; it is suggested that exposure to temperatures in excess of 22° C, as for example during low tides in the summer, might result in a cumulative stress on these populations of mussels by imposing a metabolic deficit which must be recovered at each subsequent high tide. The high mechanical cost of feeding imposes a more general constraint on the scope for activity of the species.     

Effect of Ambient Temperature on the Body Temperature Rhythm of Male Gray Mouse Lemurs (Microcebus murinus)

In order to cope with the seasonal variations in ambient temperature and food availability in the natural habitat, gray mouse lemurs (Microcebus murinus) exhibit adaptive energy-saving mechanisms similar to those in hibernating species with seasonal and daily heterothermia. To determine thermoregulatory responses, via telemetry we recorded body temperature and locomotor activity variations during the breeding season in three captive male mouse lemurs kept at ambient temperatures (T_a) ranging from 18° to 34°C. Rhythms in body temperature and locomotor activity were clearly exhibited regardless of ambient temperature. As _a increased, mean body temperature increased from 36.5 ± 0.1°C to 37.6 ± 0.3°C, with significant change in the amplitude of the body temperature rhythm when _a rose above 28°C. Effects of _a were mostly due to changes in the fall in body temperature occurring daily at the beginning of the light phase when the subjects entered diurnal sleep. The daily decrease in body temperature was not modified by exposure to ambient temperatures from 18°C to 28°C whereas it disappeared under warmer condition. Changes in locomotor activity levels only delayed the occurrence of thermoregulatory modulation. These results strongly suggest that, during the breeding season, the thermoneutral zone of mouse lemurs is close to 28°C and that the diurnal fall in body temperature could be considered as an important adaptive energy-saving mechanism adjusted to ecological constraints.     

The use of a temperature-profiled position transducer for the study of low-temperature growth in Gramineae

A device is described for measuring linear extension of grass leaves during controlled cooling and heating of the growing region. The instrument was employed to investigate the sensitivity to temperature of the expanding third and fourth leaves of Lolium temulentum L. seedlings. Using a stepped temperature profile it was established that there was no lag in the response of growth rate to rapid changes in temperature below 16°C. If cooling was continued to the point where growth ceased (1°C) but no further, then rates of growth on rewarming were enhanced over the chilling range and reverted to the original rate at 20°C. Cooling to successively lower subzero temperatures before rewarming abolished the hysteretic enhancement, progressively raised the temperature at which growth resumed and decreased the rate of extension until, at-5.3°C, no recovery occurred. The temperature sensitivity of growth, measured as Q₁₀, was essentially constant when cooling from 20°C to 5°C, with 5°C-grown leaf tissue exhibiting a higher mean Q₁₀ than tissue developed at 20°C. The possible physiological significance of these data is discussed.Abbreviations LVDT linear variable displacement transformer - Pe, Fx temperatures at which growth ceases during cooling and resumes during rewarming     

Effects of temperature on the properties of primary auditory fibres of the spectacled caiman,Caiman crocodilus (L.)

Summary The effect of temperature on the response properties of primary auditory fibres in caiman was studied. The head temperature was varied over the range of 10–35 ° C while the body was kept at a standard temperature of 27 °C (T_s). The temperature effects observed on auditory afferents were fully reversible. Below 11 °C the neural firing ceased.The mean spontaneous firing rate increased nearly linearly with temperature. The slopes in different fibres ranged from 0.2–3.5 imp s^–1 °C^–1. A bimodal distribution of mean spontaneous firing rate was found (<20 imp s^–1 and >20 imp s^–1 at T_s) at all temperatures.The frequency-intensity response area of the primary fibres shifted uniformly with temperature. The characteristic frequency (CF) increased nearly linearly with temperature. The slopes in different fibres ranged from 3–90 Hz °C^–1. Expressed in octaves the CF-change varied in each fibre from about O.14oct °C^–1 at 15 °C to about 0.06 oct °C^–1 at 30 °C, irrespective of the fibre's CF at T_s. Thresholds were lowest near T_s. Below T_s the thresholds decreased on average by 2dB°C^–1, above T_s the thresholds rose rapidly with temperature. The sharpness of tuning (Q_10db) showed no major change in the temperature range tested.Comparison of these findings with those from other lower vertebrates and from mammals shows that only mammalian auditory afferents do not shift their CF with temperature, suggesting that a fundamental difference in mammalian and submammalian tuning mechanisms exists. This does not necessarily imply that there is a single unifying tuning mechanism for all mammals and another one for non-mammals.Abbreviations BF best frequency: frequency of maximal response at an intensity 10 dB above the CF-threshold - CF characteristic frequency - FTC frequency threshold curve, tuning curve - T _s standard temperature of 27 °C     

Phytoplankton primary production in a eutrophic cooling water pond

The seasonal variation of phytoplankton photosynthesis was measured with ¹⁴C-method in a warmed ice-free pond in central Finland. Simultaneously with in situ measurements the photosynthesis was also measured in an incubator with different water temperatures and constant light (ca. 16 W m^–2). The total annual photosynthesis was 57.2 C m^–2 a^–1. The portion of the winter and spring production of the annual photosynthesis was 18.4%, that of the autumn production ws 17.4%. Thus 64.3% of the total annual phytoplankton photosynthesis occurred in the three summer months. The range of the daily integrated photosynthesis per unit area was 1.9—563 mg C m^–2d^–1. The photosynthetic rate per unit chlorophyll a varied in situ from 0.94 to 33.1 mg C (mg chl. a)^–1 d^–1. The highest value was measured in the beginning of July and the lowest in mid-January. The photosynthetic rate increased in situ exponentially with increasing water temperature. In the incubator the highest photosynthetic rate values were also found in July and August (at+20 °C) when the phytoplankton population was increasing and the minimum values occurred after every diatom maximum both in spring and autumn. Light was a limiting factor for photosynthesis from September to Mid-January, low water temperature was a limiting factor from late January through May. The efficiency of the photosynthesis varied between 0.1 and 0.7% of P.A.R. According to the incubator experiments the Q₁₀ values for the photosynthesis were 2.45 and 2.44 for the winter population between 1 and 10° C and for the summer population between 5 and 15° C, respectively, but the Q₁₀ values decrease at the higher temperatures. The main effect of the warm effluents on the yearly photosynthesis was the increase of production in spring months due to the lack of ice cover. However, the increase of total annual phytoplankton photosynthesis was only ca. 10–15%, because the water temperature was during the spring months below 10° C.     

C4 photosynthesis in Spartina townsendii at low and high temperatures

The metabolism of ¹⁴CO₂ in the cool temperate saltmarsh grass Spartina townsendii was investigated in plants grown in their natural habitats at two temperatures. Both in the spring at 10°C and in the late summer at 25°C radioactivity was initially incorporated into the organic acids malate and aspartate and then transferred to 3-phosphoglycerate in the manner characteristic of the C₄ pathway of photosynthesis. Metabolism was not disrupted at the lower temperature as in some C₄ plants. Radioactivity was transferred more slowly from malate into alanine, glycine and serine at 10°C, but sugars were labelled equally at both temperatures.     

Thermal sensitivity of heart rate and insensitivity of blood pressure in the Antarctic nototheniid fish <Emphasis Type="Italic">Pagothenia borchgrevinki</Emphasis>

The Antarctic notothenioids are among the most stenothermal of fishes, well adapted to their stable, cold and icy environment. The current study set out to investigate the thermal sensitivity/insensitivity of heart rate and ventral aortic blood pressure of the Antarctic nototheniid fish Pagothenia borchgrevinki over a range of temperatures. The heart rate increased rapidly from –1 to 6°C (Q₁₀=2.0–3.3), but was relatively insensitive to temperature above the ~6°C lethal limit of the species (Q₁₀=1.2). The increase in heart rate from –1 to 6°C was the result of a 45% increase in excitatory adrenergic tone, masking a 37% increase in inhibitory cholinergic tone. Ventral aortic pressure was regulated well above the lethal limit, up to at least 10°C. With the return of the fish to environmental temperatures, the heart rate rapidly decreased back to control levels, while ventral aortic pressure increased and remained elevated for over an hour following a 6°C exposure.     

Comparative water relations of sub-Antarctic and continental Antarctic oribatid mites

 Water availability, in addition to cold, is important in limiting biotic distribution in the Antarctic regions. In general, inland continental Antarctic habitats are dry, relative to maritime and sub-Antarctic habitats. This investigation compares the water relations of an endemic continental Antarctic oribatid mite, Maudheimia petronia Wallwork, and two sub-Antarctic oribatid mites, Halozetes fulvus Engelbrecht and Podacarus auberti Grandjean. M. petronia showed enhanced survival of dehydrating conditions, which may be attributable to both its greater resistance to and tolerance of water loss. The estimated lethal exposure times (LT₅₀) for M. petronia, P. auberti and H. fulvus held at 15°C and 0–5% RH were 250, 135 and 51 h, respectively. M. petronia lost water significantly more slowly than the sub-Antarctic mites (P<0.05), which did not differ in their rates of water loss (P>0.05). The mean losses of initial body water content after 45 h were 18.9, 27.3 and 29.3% for M. petronia, P. auberti and H. fulvus, respectively, and lethal water losses causing 50% of the sample to die were 65, 52, and 28%, respectively. These data suggest physiological adaptation by M. petronia for existence in periodically dry “chalikosystem” habitats at Antarctic nunataks. Comparisons of tolerance of submersion in freshwater showed P. auberti to be superior to M. petronia; the LT₅₀ values for submersion were >146 h and 32 h, respectively. Tolerance of submersion by P. auberti may be important for its existence in wet sub-Antarctic habitats. Conversely, the poor tolerance shown by M. petronia suggests that this mite has not been associated with moist environments. Received: 13 April 1995/Accepted: 4 August 1995     

Reduction of acetylene by nodules of Trifolium subterraneum as affected by root temperature,Rhizobium strain and host cultivar

Summary The nitrogenase activity (measured by reduction of C₂H₂ to C₂H₄) of nodules of Trifolium subterraneum grown at root temperatures from 7°C–19°C was broadly correlated with nitrogen fixation. Root temperature did not affect enzyme activity per se but did affect the amount of enzyme formed. Exposure of nodules to 7°C for 24 h did not decrease activity cf. 19°C. Activity was greatest when nodules were about 4 days old, before swollen bacteroid forms were produced, and then declined. The effectiveness of a bacterial strain at a given temperature was related to the amount of enzyme produced and to its persistence. Nitrogenase activity should be measured throughout the plant growth cycle for valid comparisons of strain effectiveness.     

Biology, life table and host specificity of the mushroom pest, Brennandania lambi (Acari: Pygmephoroidea)

Biology and life table parameters of Brennandania lambi (Krczal) were studied at different temperatures while feeding on white mushroom (Agaricus bisporus) mycelium cultured on mushroom compost. The duration of egg and larva development, preoviposition and oviposition period, female longevity, and the time to 50% mortality declined as temperature increased from 16 to 28°C. The threshold temperature of development (female) was 9°C and the thermal constant for completion of development (female) was 195 day-degrees. At 16, 20, 24 and 28°C, the total fecundity (eggs/female) was 71, 67, 66 and 57, respectively and the daily fecundity rate (eggs/female/day) was 5.6, 8.7, 8.7 and 9.1, respectively. The sex ratio (female/male) ranged from 1.9 to 2.1 at 16–28°C. At 16, 20, 24 and 28°C, the intrinsic rate of natural increase (r _m) was 0.11, 0.18, 0.22 and 0.27, respectively, and the population doubling time was 6.1, 3.9, 3.2 and 2.5 days, respectively. All life stages of the mite died when exposed to 35°C constant temperature for 24h, or to 32°C constant temperature for 12 days or to 31–35°C (average 32.9°C) ambient temperature for 4 days. Brennandania lambi completed development only when fed on Ag. bisporus mycelium growing on mushroom compost. It could not survive on mushroom mycelia of Auricularia auricula, Au. polytricha, Ganoderma lucidum, Hericium erinaceus, Lentinus edodes, Pleurotus ostreatus, P. sajor-caju and Tremella fuciformis.     

Seasonal acclimation in metabolism reduces light requirements of eelgrass (Zostera marina)

We investigated the ability of eelgrass (Zostera marina) to adjust light requirements to seasonal changes in temperature, light and nutrient conditions through changes in metabolism, pigment and nutrient content. In agreement with expectations we found that rates of respiration and light saturated photosynthesis of summer acclimated plants peaked at higher temperatures (5 °C and 2 °C higher, respectively), and were lower than of winter acclimated plants, both at sub- and supra-optimal temperatures. Moreover respiration rates were generally more sensitive to increasing temperatures than photosynthetic rates, especially so for cold acclimated plants in February (36% higher Q₁₀-values). These changes were accompanied by a reduction in chlorophyll a and nitrogen concentrations in leaves by 35% and 60% respectively from February to August. The critical light requirement (E_C) of Z. marina to maintain a positive carbon balance increased exponentially with increasing temperature but less so for summer-acclimated than for winter-acclimated plants. However, combining E_C vs temperature models for whole-plants with data on daily light availability showed that seasonal acclimation in metabolism increased the annual period, when light requirements were meet at the 2-5 m depth interval, by 32-66 days. Hence, acclimation is an important mechanism allowing eelgrass to grow faster and penetrate to deeper waters. Critical depth limits estimated for different combinations of summer temperatures and water clarity in a future climate scenario, suggested that expected increases in temperature and nutrient run-off have synergistic negative effects, especially in clear waters, stressing the importance of continued efforts to improve water clarity of coastal waters.     

Weather,microclimate, and energy costs of thermoregulation for breeding Adélie Penguins

Summary We measured meteorological conditions and estimated the energy costs of thermoregulation for young and adult Adélie Penguins (Pygoscelis adeliae) at a breeding colony near the Antarctic Peninsula. Air temperatures averaged < 5°C and strong winds were frequent. Operative temperatures (T_e) for adults ranged from –8 to 28°C, averaging 5–6°C, for the period from courtship to fledging of chicks. The average energy cost of thermoregulation (C_th) for adult penguins was equivalent to 10–16% of basal metabolism. C_th comprised about 15% of the estimated daily energy budget (DEB) of incubating adults, but only about 1% of the DEB of adults feeding chicks. The T_e's for chicks older than 14 days ranged from 0 to 31°C, averaging 8.0 C. The C_th for downy chicks ranged from about 31% of minimal metabolic rate (MMR) in 1 kg chicks to about 10% of MMR in 3 kg chicks. Between initial thermal independence (age 12–14 days) and the cessation of parental feeding (age 35–40 days), chicks use about 10–11% of assimilated energy for thermoregulation. C_th is equivalent to about 17% of the MMR of fledglings during their 2–3 week fast. We observed no indication of thermal stress (i.e., conditions in which birds cannot maintain stable T_b) in adults and no indication of cold stress in any age class. However, on clear, calm days when air temperature exceeds 7–10°C for several hours, downy chicks are vulnerable to lethal hyperthermia.     

Effects of light and temperature on sporangiophore initiation in Pilobolus crystallinus (Wiggers) Tode

Sporangiophore initiation in Pilobolus crystallinus grown in white light was induced by either a dark or a low-temperature treatment. The period of darkness necessary to induce sporangiophore initiation was shortened by lowering the temperature. Arrhenius plots for the sporangiophore-suppressing reaction in both light and darkness consisted of two straight lines with a Q₁₀ of about 2 at lower temperatures and 8–11 at higher temperatures. The temperature at which the Q₁₀ changed was the lower, the higher the fluence rate: 14° C at 8 W/m², 19.5° C at 0.24 W/m² and 24.5° C in darkness. Possible interpretations of these results are briefly presented.Abbreviations %SP percentage of trophocysts initiating sporangiophores - D50% duration of treatment required to 50% sporangiophore initiation     

Effects of temperature on survival, development, growth and feeding of larvae of Yellowtail clownfish Amphiprion clarkii (Pisces: Perciformes)

To understand the physiological and ecological responses of marine fishes to the change of water temperature, newly-hatched larvae of Yellowtail clownfish Amphiprion clarkii were reared in captivity at water temperatures of 23, 26 and 29 °C till they completed the metamorphosis to juvenile phase, and larval survival, development, growth and feeding were evaluated during the experimental period. The results showed that water temperature influenced the physiological performance of larvae of A. clarkii significantly. The survival and growth rates of larvae of A. clarkii increased significantly with the increase of water temperature from 23 to 29 °C (P < 0.05). Water temperature also influenced larval development of A. clarkii significantly and larvae reared at 23 °C took longer time for post-larval development and metamorphosis compared to 26 and 29 °C (P < 0.05). Total length and body weight for post-larval development and metamorphosis decreased with the increase of water temperature from 23 to 29 °C (P < 0.05). Q₁₀ in developmental rate was higher than in daily growth rate at the same rearing temperature, indicating that at water temperature had greater influence on larval development than on growth. Water temperature also influenced larval feeding of A. clarkii significantly with feed ration (FR) and feed conversion efficiency (FCE) increased with the increase of water temperature from 23 to 29 °C (P < 0.05). There was a positive correlation between FR and specific growth rate (SGR) (P < 0.05) but not between FCE and SGR (P > 0.05), indicating that FR influenced growth rate significantly in larvae of A. clarkii. This study demonstrated that the physiological responses of larvae of A. clarkii to the change of water temperature and confirmed that water temperature influenced larval survival, development, growth and feeding significantly. This study suggests that the decline of larval survival and growth rates, extension of pelagic larval duration and reduction of larval feeding at lower temperature have ecological impacts on larval dispersal and metamorphosis, juvenile settlement and population replenishment in A. clarkii in the wild.     

Effects of temperature on properties of flight neurons in the locust

High ambient temperatures increase the wing-beat frequency in flying locusts, Locusta migratoria. We investigated parameters of circuit and cellular properties of flight motoneurons at temperatures permissive for flight (20–40 °C). As the thoracic temperature increased motoneuronal conduction velocity increased from an average of 4.40 m/s at 25 °C to 6.73 m/s at 35 °C, and the membrane time constant decreased from 11.45 ms to 7.52 ms. These property changes may increase locust wing-beat frequency by affecting the temporal summation of inputs to flight neurons in the central circuitry. Increases in thoracic temperature from 25–35 °C also resulted in a hyperpolarization of the resting membrane potentials of flight motoneurons from an average of-41.1 mV to -47.5 mV, and a decrease of input resistances from an average of 3.45 M to 2.00 M. Temperature affected the measured input resistance both by affecting membrane properties, and by altering synaptic input. We suggest that the increase in conduction velocity Q₁₀=1.53) and the decrease of membrane time constant (Q₁₀=0.62) would more than account for the wing-beat frequency increase (Q₁₀=1.15). Hyperpolarization of the resting membrane potential (Q₁₀=1.18) and reduction in input resistance (Q₁₀=0.54) may be involved in automatic compensation of temperature effects.Abbreviations ANOVA analysis of variance - CPG central pattern generator - DL dorsal longitudinal muscles - EMG electromyographic - MN motoneuron - PSP post synaptic potential - Q₁₀ temperature coefficient - RMP resting membrane potential - S.D. standard deviation - SR stretch receptor     

Growth and development of Hydromedion sparsutum (Müller) (Coleoptera,Perimylopidae) from South Georgia at different temperatures

Summary Adaptation of Hydromedion sparsutum (Coleoptera, Perimylopidae) to the cool, moderate climate of South Georgia Island was studied under lab conditions. Because there are no native vertebrate herbivores on the island, the Perimylopidae as primary destruents occupy an important role in the ecosystem of S. G. H. sparsutum was reared at constant temperatures of 4, 7.5, 10, 12.5 and 14°C. Constant temperatures higher than 10°C are lethal to the population, larvae do not develop to imaginal stage. Developmental speed and growth are slightly temperature compensated between 4 and 7.5°C. The Q₁₀-value of the weekly growth rate for this range is 1.23.     

Energy consumption and metabolism during starvation in the Arctic hyperiid amphipod Themisto libellula Mandt

When the Arctic hyperiid amphipod Themisto libellula was starved for a month the lipid and energy content decreased. Over the first two weeks 5.50 g lipid and 0.24 joules were consumed per mg dry weight·d, but rates of lipid and energy consumption decreased by 70–75% during the subsequent two weeks. An individual with maximum lipid reserve could survive for about 168 days without food. Given that lipid is also needed for reproduction in mid-winter, it seems unlikely that animals could overwinter without feeding. Temperatures between 0° and 6° C had only a slight effect (Q₁₀ = 1.61) on the rate of lipid and energy consumption. The effect of temperatures in the normal habitat range on the rate of respiratory metabolism was also small (Q₁₀ = 2.01), but above 5°C the rate increased sharply (Q₁₀ = 6.5). Starvation for 15 days had no significant effect on the animals' metabolic rate.