Effects of long-term captivity on thermoregulation,metabolism and ventilation of the southern brown bandicoot (Marsupialia: Peramelidae)

Thermoneutral metabolic and ventilatory parameters were measured every 3 months over 2 years for southern brown bandicoots held in captivity, and from a nearby reserve. Captive bandicoots were 130 g (9.9%) heavier than wild bandicoots. Long-term captivity had no effect on body temperature, basal metabolic rate (oxygen consumption), thermal conductance or respiratory ventilation, but there was an effect on carbon dioxide production, respiratory exchange ratio and total evaporative water loss (values were between 15 and 25% higher for captive than for wild bandicoots). Diet may be influencing these aspects of captive bandicoot physiology; the diet of captive bandicoots would be considerably different to that of wild bandicoots. Water availability seems to have a minimal effect. This study has important implications regarding physiological measurement for captive and wild mammals. For bandicoots at least, captive animals are equivalent to wild animals for some physiological parameters at thermoneutrality (body temperature, resting metabolic rate and thermal conductance), but not others.     

Body temperature variation of free-ranging and captive southern brown bandicoots Isoodon obesulus (Marsupialia: Peramelidae)

To investigate patterns of thermoregulation in free-ranging and captive southern brown bandicoots Isoodon obesulus, we measured abdominal body temperature (T_b) of five free-ranging bandicoots over 42 days using implanted data loggers and T_b of three captive bandicoots over 3 months using implanted temperature-sensitive radio transmitters. Bandicoots in the wild had a mean T_b of 36.5±1.0 °C (range 33.4–39.8 °C) and showed a pronounced nychthemeral pattern with two distinct temperature phases. T_b increased at 13:30±2.6 h each day and remained high for 10.65±2.07 h, suggesting a crepuscular and early evening activity pattern. Daily T_b variation of I. obesulus would save considerable energy by reducing daytime thermoregulatory costs in the wild. Captive bandicoots had a similar mean body temperature (36.9±0.2°C) and range (33.0–39.9°C) as free-ranging bandicoots. However, the nychthemeral T_b pattern of captive bandicoots was different from free-ranging bandicoots, with a less pronounced daily cycle and the nocturnal rise in T_b occurring mainly at sunset and the daily decline occurring mainly at dawn.     

Thermogenic characteristics and evaporative water loss in the tree shrew (Tupaia belangeri)

Thermogenic characteristics and evaporative water loss were measured at different temperatures in Tupaia belangeri. The thermal neutral zone (TNZ) of T. belangeri was 30–35 °C. Mean body temperature was 39.76±0.27 °C and mean body mass was 100.86±9.09 g. Basal metabolic rate (BMR) was 1.38±0.03 ml O₂/g h. Average minimum thermal conductance (C_m) was 0.13±0.01 ml O₂/g h °C. Evaporative water loss in T. belangeri increased when the temperature rose; the maximal evaporative water loss was 3.88±0.41 mg H₂O/g h at 37.5 °C. The results may reflect features of small mammals in the sub-tropical plateau region: T. belangeri had high basal metabolic rate and high total thermal conductance, compared with the predicted values based on their body mass whilst their body temperatures are relatively high; T. belangeri has high levels of evaporative water loss and poor water-retention capacity. Evaporative water loss plays an important role in temperature regulation.     

Metabolism,thermoregulation and evaporative water loss in the Chaotung Vole (Eothenomys olitor) in Yunnan-Kweichow Plateau in summer

Proper adjustment of thermoregulatory mechanisms ensures the survival of mammals when they are subjected to seasonal changes in their natural environment. To understand the physiological and ecological adaptations of Eothenomys olitor, we measured their metabolic rate, thermal conductance, body temperature (T_b) and evaporative water loss at a temperature range of 5–30 °C in summer. The thermal neutral zone (TNZ) of E. olitor was 20–27.5 °C, and the mean body temperature was 35.81±0.15 °C. Basal metabolic rate (BMR) was 2.81±0.11 ml O₂/g h and mean minimum thermal conductance (C_m) was 0.18±0.01 ml O₂/g h °C. Evaporative water loss (EWL) in E. olitor increased when the ambient temperature increased. The maximal evaporative water loss was 6.74±0.19 mg H₂O/g h at 30 °C. These results indicated that E. olitor have relatively high BMR, low body temperature, low lower critical temperature, and normal thermal conductance. EWL plays an inportant role in temperature regulation. These characteristics are closely related to the living habitat of the species, and represent its adaptive strategy to the climate of the Yunnan-Kweichow Plateau, a low-latitude, high-altitude region where annual temperature fluctuations are small, but daily temperature fluctuations are greater.     

Shivering and non-shivering thermogenesis in a marsupial,the eastern barred bandicoot (Perameles gunnii)

We investigated the metabolic rate of the Tasmanian marsupial, the eastern barred bandicoot, Perameles gunnii, before and after acclimation to cold temperature (5 °C) for a 2-week period. Although body temperature did not change significantly, we observed a significant increase in the metabolic rate (MR) when measured at 5 °C before and after cold acclimation. Nor-epinephrine had a significant effect on the metabolic rate when measured in the thermoneutral zone and when measured at 5 °C after cold acclimation; however, there was no significant increase when measured at 5 °C before cold acclimation. Nor-epinephrine also resulted in a small but significant decrease in body temperature. Electromyography (EMG) measurements were obtained before and after cold acclimation during shivering. Shivering decreased after two weeks of cold exposure indicating that the bandicoot had acclimated to that temperature. Nor-epinephrine (NE) significantly reduced shivering before but not after cold acclimation. The metabolic rate and shivering decreased in the adult eastern barred bandicoot after acclimation at 5 °C and nor-epinephrine had similar effects to cold acclimation. Our findings of minor changes in thermal conductance suggest that insulation differences were unlikely explanations for our results. These experiments indicate that this marsupial is able to increase its heat production by non-shivering thermogenesis.     

The behavioural ecology and population dynamics of a cryptic ground‐dwelling mammal in an urban Australian landscape

Urbanization results in widespread habitat loss and fragmentation and generally has a negative impact upon native wildlife, in particular ground‐dwelling mammals. The northern brown bandicoot (Isoodon macrourus; Marsupialia: Peramelidae) is one of relatively few native Australian ground‐dwelling mammals that is able to survive within urbanized landscapes. As a consequence of extensive clearing and urban development within the city of Brisbane, bandicoots are now restricted to the mostly small (<10 ha) bushland fragments scattered across the city landscape. Our study examined the behavioural ecology of northern brown bandicoots within habitat fragments located on a major creek‐line, using mark‐recapture population monitoring and radio telemetry. Bandicoots at monitored sites were found to occur at high densities (typically one individual ha^?1), although one‐third of the populations were transient. Radio tracking revealed that bandicoots had relatively small home ranges (mean 1.5 ± 0.2 ha) comprised largely of bushland/grassland with dense, often weed‐infested ground cover. Bandicoots sheltered by day in these densely covered areas and also spent most time foraging there at night, although they occasionally ventured small distances to forage in adjacent maintained parklands and residential lawns. We suggest that introduced tall grasses and other weeds contribute to high habitat quality within riparian habitat fragments and facilitate the persistence of high density populations, comprised of individuals with small home ranges. The generalized dietary and habitat requirements of northern brown bandicoots, as well as a high reproductive output, undoubtedly facilitate the survival of the species in urban habitat fragments. Further research is required on other native mammal species in urbanized landscapes to gain a greater understanding of how best to conserve wildlife in these heavily modified environments.     

Changes in mammal populations in relatively intact landscapes of Kakadu National Park,Northern Territory,Australia

A previous study ( Braithwaite & Muller 1997 ) reported substantial declines in mammal abundance over the period 1986–1993 for a large study area (300 km²) within Kakadu National Park in the tropical savannas of northern Australia. This decline was reported as being a ‘natural’ response to fluctuating groundwater levels, driven by runs of poor wet seasons. We resampled mammals in this area in 1999, following a series of unusually good wet seasons, and examined the prediction that mammal numbers should have recovered. Increases in abundance were evident for four species: the smallest dasyurid (red‐cheeked dunnart Sminthopsis virginiae) and the three smallest rodents (delicate mouse Pseudomys delicatulus, western chestnut mouse Pseudomys nanus and grassland melomys Melomys burtoni). In contrast, the abundance of all mammals combined and that for seven individual mammal species (northern quoll Dasyurus hallucatus, fawn antechinus Antechinus bellus, common brushtail possum Trichosurus vulpecula, northern brown bandicoot Isoodon macrourus, dusky rat Rattus colletti, black‐footed tree‐rat Mesembriomys gouldii and pale field rat Rattus tunneyi) continued to decline. The decline in abundance of these mammal species is consistent with limited observations elsewhere in northern Australia. Although far from conclusive, these observations suggest that the biota of the vast relatively undisturbed tropical savannas can no longer be assumed to be intact nor safe. Further research is needed to test this possible pattern of decline and, if confirmed, to identify and ameliorate the processes contributing to it.     

Effect of season on thermoregulation, metabolism and ventilation of the southern brown bandicoot Isoodon obesulus (Marsupialia: Peramelidae)

Seasonal variation in various thermoregulatory, metabolic and ventilatory parameters was examined for southern brown bandicoots (Isoodon obesulus fusciventer) from a Mediterranean climate near Perth, Western Australia. There was significant seasonal variation over the four annual seasons at thermoneutrality (Ta=30 degrees C) in body temperature, oxygen consumption, carbon dioxide production, respiratory exchange ratio, total evaporative water loss, wet and dry thermal conductance and tidal volume but not mass, ventilatory frequency, minute volume or oxygen extraction efficiency. Only carbon dioxide production and respiratory exchange ratio showed an annual pattern that was significantly related to season, with both being significantly higher in winter, presumably as a result of greater and higher quality food availability.     

Metabolic thermogenesis and evaporative water loss in the Hwamei Garrulax canorus

Basal metabolic rate (BMR) is thought to be a major hub in the network of physiological mechanisms connecting life history traits. Evaporative water loss (EWL) is a physiological indicator that is widely used to measure water relations in inter- or intraspecific studies of birds in different environments. In this study, we examined the physiological responses of summer-acclimatized Hwamei Garrulax canorus to temperature by measuring their body temperature (T_b), metabolic rate (MR) and EWL at ambient temperatures (T_a) between 5 and 40 °C. Overall, we found that mean body temperature was 42.4 °C and average minimum thermal conductance (C) was 0.15 ml O₂ g⁻¹ h⁻¹ °C⁻¹ measured between 5 and 20 °C. The thermal neutral zone (TNZ) was 31.8–35.3 °C and BMR was 181.83 ml O₂ h⁻¹. Below the lower critical temperature, MR increased linearly with decreasing T_a according to the relationship: MR (ml O₂ h⁻¹)=266.59–2.66 T_a. At T_as above the upper critical temperature, MR increased with T_a according to the relationship: MR (ml O₂ h⁻¹)=−271.26+12.85 T_a. EWL increased with T_a according to the relationship: EWL (mg H₂O h⁻¹)=−19.16+12.64 T_a and exceeded metabolic water production at T_a>14.0 °C. The high T_b and thermal conductance, low BMR, narrow TNZ, and high evaporative water production/metabolic water production (EWP/MWP) ratio in the Hwamei are consistent with the idea that this species is adapted to warm, mesic climates, where metabolic thermogenesis and water conservation are not strong selective pressures.     

Participation of book lungs in evaporative water loss in Paraphysa parvula, a migalomorph spider from Chilean Andes

Small animals need efficient water conservation mechanisms for survival and reproduction, which is relevant for the spiders that have large book lungs with large respiratory surface. If lung evaporation is relevant to limit water loss, adjustments of the spiracle opening to metabolic demands should be expected. In this study, we measured the metabolic rate and total evaporative water loss mediated by the opening of the spiracles in the migalomorph spider Paraphysa parvula, a resident of fluctuating Mediterranean environments of the mountains of central Chile. We found that the metabolism of P. parvula was similar to other Theraphosidae and low compared to other arthropods. Carbon dioxide production and evaporative water loss increased with temperature, particularly at 40 °C. The total evaporative water loss at 40 °C increased dramatically to about 10 times that found with the lower temperatures. Thus, 40 °C will be the limit temperature for this species after which evaporative water loss starts to become damaging, so it has to avoid it. The exposition to hypercapnic environments had as a consequence an increase in evaporative water loss and the involvement of the book lungs in this loss was about 60%. The possibility of losing water could condition this species to seek temperate and oxygenated shelters under rocks.     

Physiological variability in the Fiscal Shrike Lanius collaris along an altitudinal gradient in South Africa

Oxygen consumption, evaporative water loss and body temperature were investigated in four subpopulations of sedentary Fiscal Shrike in South Africa across an altitudinal gradient from east to west. Subpopulations were found to be significantly different in the physiological parameters investigated. Fiscal Shrikes from the more mesic habitats at low altitude (Durban and Merrivale) were found to have higher basal metabolic rates, evaporative water loss and body temperatures, compared with shrikes from semi-arid areas of low habitat productivity at high altitude (Estcourt and Harrismith). Fiscal Shrikes also displayed significant differences in circadian rhythms of oxygen consumption, evaporative water loss and body temperature. Fiscal Shrikes showed seasonal acclimatisation of thermoregulatory parameters, increasing their basal metabolic rates and oxygen consumption in cold conditions, and reducing their body temperatures from summer to winter. Deviations of physiological parameters from those predicted by allometry were attributed to the plasticity at a phenotypic level that allows survival in a range of environmental conditions associated with unpredictable resource availability in southern Africa.     

Responses of the digestive tract of the omnivorous northern brown bandicoot, Isoodon macrourus (Marsupialia: Peramelidae), to plant- and insect-containing diets

The gastrointestinal tract of omnivores such as bandicoots (Marsupialia: Peramelidae) must be able to process foods as different as invertebrates, fungi and plant material. We studied the mechanisms involved in the utilisation by captive northern brown bandicoots (Isoodon macrourus) of insect larvae and milled lucerne (Medicago sativa) hay incorporated into a basal diet of a commercial small carnivore mix. Animals on the plant-basal mix digested less dry matter, energy, lipid, fibre and total nitrogen, but consumed 79% more dry matter than those on the insect-basal mix. Consequently intake of digestible energy (i.e. energy absorbed) was not significantly different between diets. Mean retention time (MRT, the mean time a marker remains in the tract) of a large particle marker was shorter on the plant-basal mix, reflecting its higher intake, but MRT of a solute marker was not significantly different between diets. Consequently the solute marker was retained longer than the particle marker on the plant-basal mix, indicating selective retention of solutes and very small particles in the caecum on this diet. This was confirmed by a higher proportion of small particles in the caecum than the distal colon of road-killed I. macrourus. Thus the main responses by I. macrourus to the plant-basal mix appeared to be an increase in gastrointestinal tract capacity (from radiographic evidence), selective retention of solutes and very small particles in the caecum, and facilitated passage of less tractable large particles through the colon. As a consequence, food intake was higher on the plant-basal mix, which compensated for its lower digestibility, and intake of digestible energy was similar to that on the insect-basal mix. This considerable flexibility of the morphologically rather simple digestive tract of northern brown bandicoots helps to explain their ability to cope with naturally variable diets consisting of mainly invertebrates in summer to much more plant and fungal material in winter, and to survive in nutritionally dynamic environments such as heathlands where there can be dramatic changes in food type and availability following periodic wildfires. Accepted: 14 April 1999     

The effect of supplementary food on home range of the southern brown bandicoot,Isoodon obesulus (Marsupialia: Peramelidae)

The study investigated the relationship between home range and food abundance in a population of the southern brown bandicoot. Isoodon obesulus, in Western Australia. Home range areas were estimated seven times between 1986 and 1988 by live-trapping, spool-and-line devices and fluorescent pigment tracking. The abundance of invertebrate food was measured simultaneously by placing pitfall traps within the home ranges of individual animals, and by sampling invertebrates in topsoil and litter. Home range areas tended to be negatively correlated with food abundance, especially in the autumn and winter of 1986 and 1987. The influence of food on home range was investigated further in September 1988 by providing eight individual I. obesulus with a supplementary food mixture. Contrary to expectation, the added food caused an increase in home range area, home range overlap and displacement, as well as an influx of new individuals to food stations. In contrast, home range parameters in control (non-fed) individuals changed little during the experiment. The shuffling of home ranges due to feeding suggests that the home range system of I. obesulus is relatively flexible, with individuals monitoring and exploiting resources in an opportunistic manner. In contrast to previous studies, we found no evidence that I. obesulus was territorial. We speculate that individuals may be territorial at low population density if resources are defendable and intruder pressure is low, but occupy overlapping ranges if population density is high.     

Evaporative cooling and endothermy in the 13-year periodical cicada,Magicicada tredecem (Homoptera: Cicadidae)

Summary The thermobiology of a cicada, Magicicada tredecem, from a warm, high humidity environment was investigated. Thoracic temperature (T_th) of M. tredecem in the field was strongly dependent on, and consistently higher than, ambient temperature (T_am), averaging 33.0±0.19°C on warm sunny days (T_am=28–29°C, rh=60–75%). Laboratory studies documented cuticle water fluxes high enough ( 5mg · cm^–2 · h^–1 in dry air at 40°C) to result in a significant degree of passive evaporative cooling, but the ability of M. tredecem to actively facilitate evaporative water loss during thermal stress is comparatively limited: water loss rates (WLR) of live M. tredecem at 40°C (dry air) were only 35–45% greater than those of dead cicadas. The limited ability of M. tredecem to facilitate transcuticular WLR is associated with limited surface distribution of the cuticular ducts through which water is actively extruded during evaporative cooling. In the laboratory, active extrusion of water had no appreciable effect on T_th, demonstrating that evaporative cooling was due largely to passive water flux through the highly permeable cuticle. The location of the abdominal pore tracts is such that extrusion of water through the ducts may preferentially cool the heart and perhaps other abdominal tissues. Long-term climatological data indicate that M. tredecem rarely encounters T_am levels high enough (i.e., above its apparent T_th setpoint of 34–35°C) to require evaporative cooling. Inactive M. tredecem can endothermically increase T_th. An hypothesis is proposed to account for the diversity of body temperature setpoints in cicadas.Abbreviations rh relative humidity - SOT standard operating temperature - T _am ambient temperature - T _b body temperature - T _sp body temperature setpoint - T _th thoracic temperature - TWF transcuticular water flux - WLR water loss rate     

Evidence for the coexistence of serotonin and calcitonin gene-related peptide at the subcellular level in neuroepithelial bodies in the lung of a marsupial,Isoodon macrourus

Summary The coexistence of serotonin and calcitonin gene-related peptide (CGRP) in neuroepithelial bodies of the bandicoot, Isoodon macrourus, has been examined using immunocytochemistry at the light- and electronmicroscope levels. The avidin-biotin technique of antigen localisation was used initially to identify serotonin-like and CGRP-like immunoreactivity (-LI). Serotonin-LI and CGRP-LI were found in neuroepithelial cells in the lungs of 30-day-old bandicoots. CGRP-LI could also be demonstrated in nerve fibres associated with some neuroepithelial bodies. The protein A-gold technique of antigen localisation was used to label neuroepithelial cells and nerve fibres at the subcellular level. Serotonin-LI and CGRP-LI were observed in the same dense-cored vesicles of most neuroepithelial cells; however, some neuroepithelial cells were shown to possess serotonin-LI without CGRP-LI. Nerve fibres immediately adjacent to neuroepithelial bodies exhibited mainly CGRP-LI. These results show that serotonin-LI and CGRP-LI are present in neuroepithelial cells of the bandicoot in the same secretory vesicles. This pattern of co-localisation may reflect co-ordinated or synergistic actions of these two neuroactive substances.     

Isolation and characterization of microsatellite loci in the southern brown bandicoot (Isoodon obesulus), and their applicability to other marsupial species

The southern brown bandicoot (Isoodon obesulus) was once widely distributed throughout coastal regions of Australia, however, populations have now become fragmented and the number of individuals are declining rapidly. As a result, this species is now classified as endangered in New South Wales and requires management. We have developed eight microsatellite markers to investigate levels of genetic variation and subdivision among these isolated populations. These microsatellite markers show levels of variability ranging from four to eight alleles and observed heterozygosities of 0.353–0.938. These microsatellite markers are also suitable for similar population studies on other related marsupials.     

Effects of temperature on metabolism,ventilation, and oxygen extraction in the southern brown bandicoot Isoodon obesulus (Marsupialia: Peramelidae)

The effects of ambient temperatures (T(a)) from 10 degrees to 35 degrees C on metabolism, ventilation, and oxygen extraction were examined for the southern brown bandicoot (Isoodon obesulus). Oxygen consumption (VO2) followed the pattern typical for endotherms, decreasing with increasing T(a) from 10 degrees to 25 degrees C. It did not significantly change between Ta=25 degrees and 35 degrees C (the thermoneutral zone). VO2 was approximately 2.4 times higher at Ta=10 degrees C (0.967 mL O(2) g(-1) h(-1)) compared with basal (0.410 mL O(2) g(-1) h(-1)) at Ta=30 degrees C. While the metabolic rates of the bandicoots were basal at Ta=30 degrees C, respiratory frequency (f(R)) was 24.6 breaths min(-1), tidal volume (V(T)) was 7.79 mL, minute volume (V(I)) was 191.3 mL min(-1), and oxygen extraction efficiency (EO2) was 26.8%. Increased VO2 at Ta< or =25 degrees C was associated with a large increase in V(I) due to increases in V(T) and f(R). A greater proportion of the change was due to the increase in tidal volume. EO2 was constant at approximately 26% for all T(a) up to and including 30 degrees C. At Ta=35 degrees C, EO2 decreased to 17.7%, f(R) increased to 35.6 breaths min(-1), and V(T) decreased to 7.22 mL. The metabolic and ventilatory physiology of the southern brown bandicoot are typical of an unspecialized medium-sized marsupial.     

Physiological regulation of evaporative water loss in endotherms: is the little red kaluta (Dasykaluta rosamondae) an exception or the rule?

It is a central paradigm of comparative physiology that the effect of humidity on evaporative water loss (EWL) is determined for most mammals and birds, in and below thermoneutrality, essentially by physics and is not under physiological regulation. Fick''s law predicts that EWL should be inversely proportional to ambient relative humidity (RH) and linearly proportional to the water vapour pressure deficit (Δwvp) between animal and air. However, we show here for a small dasyurid marsupial, the little kaluta (Dasykaluta rosamondae), that EWL is essentially independent of RH (and Δwvp) at low RH (as are metabolic rate and thermal conductance). These results suggest regulation of a constant EWL independent of RH, a hitherto unappreciated capacity of endothermic vertebrates. Independence of EWL from RH conserves water and heat at low RH, and avoids physiological adjustments to changes in evaporative heat loss such as thermoregulation. Re-evaluation of previously published data for mammals and birds suggests that a lesser dependence of EWL on RH is observed more commonly than previously thought, suggesting that physiological independence of EWL of RH is not just an unusual capacity of a few species, such as the little kaluta, but a more general capability of many mammals and birds.     

Fine‐scale habitat preferences and habitat partitioning by three mycophagous mammals in tropical wet sclerophyll forest,north‐eastern Australia

Abstract Fine‐scale habitat preferences of three co‐occurring mycophagous mammals were examined in a tropical wet sclerophyll forest community in north‐eastern Australia. Two of the three mammal species responded to fine‐scale variation in vegetation and landform around individual trap locations. At a broad scale, the northern bettong (Bettongia tropica), an endangered marsupial endemic to the Australian wet tropics region, showed a preference for ridges over mid‐slopes and gullies, irrespective of forest type. In contrast, the northern brown bandicoot (Isoodon macrourus), a widespread marsupial, displayed a preference for Eucalyptus woodland over adjacent Allocasuarina forest, irrespective of topographic category. The giant white‐tailed rat (Uromys caudimaculatus), a rodent endemic to the wet tropics, showed no particular preference for either forest type or topographic category. A multiple regression model of mammal capture success against three principal habitat gradients constructed from 21 habitat variables using principal component analysis indicated strong species‐specific preferences for fine‐scale vegetation assemblages. Bettongs preferred areas of Eucalyptus woodland with sparse ground cover, low densities of certain grass species, high density of tree stems and few pig diggings. Bandicoots, in contrast, favoured areas in both forest types with dense ground cover, fewer tree stems and greater numbers of pig diggings; that is, characteristics least favoured by bettongs. The striking differences in fine‐scale habitat preferences of these two mammals of similar body size and broad habitat requirements suggest a high degree of fine‐scale habitat partitioning. White‐tailed rats did not show preference for any of the habitat gradients examined.     

Interactive effects of food availability and aerial body temperature on the survival of two intertidal Mytilus species

Intertidal organisms must episodically contend with the rigors of both the terrestrial and the marine environments. While body temperatures during high tide are driven primarily by water temperature, aerial body temperatures are driven by multiple environmental factors such that temperature of an organism during low tide is usually quite different from air temperature. Thus, whereas decades of research have investigated the effects of water temperature on intertidal species, considerably less is known about the physiological impacts of temperature during aerial exposure at low tide, especially with regard to the interaction of aerial body temperature with other stressors. We examined the interactive effects of aerial body temperature and food supply on the survival of two intertidal blue mussels, Mytilus galloprovincialis and Mytilus trossulus. Survival was monitored for nine weeks using a simulated tidal cycle, with two levels of food and three levels of aerial body temperature (30, 25, and 20 °C). Decreased food supply significantly reduced the survival of mussels, but only under the 30 °C treatment. In the other two thermal regimes there were no significant effect of food on survival. When aerial body temperatures are high, food availability may have a greater effect on intertidal organisms. Decreases in ocean productivity have been linked to increased in ocean temperatures, thus intertidal organisms may become more susceptible to thermal stress as climates shift.