Metabolic Rate Activity Research Articles

Plasticity of thermal tolerance and metabolism but not water loss in an invasive reed frog

Phenotypic plasticity may buffer the selection pressures on organisms that inhabit novel or rapidly-changing environments. We investigated plasticity of thermal tolerance, energetic and water loss traits and their interaction with behaviour in a small-bodied, arboreal anuran (Hyperolius marmoratus Rapp, Hyperoliidae) undergoing rapid range expansion into the winter rainfall region of South Africa. After short-term exposure to three temperatures (acclimation treatments) commonly encountered in their historical and novel ranges, frogs exhibited a broad thermal tolerance range (mean±s.d.: 42.1±2.9°C) and higher plasticity in CTmax than in CTmin. Resting metabolic rate was lowest in cold-acclimated animals, while active metabolic rates were lowest in warm-acclimated frogs, likely reflecting compensation towards energy conservation. Evaporative water loss was not significantly altered by the acclimation treatments in either resting or active animals, indicating limited plasticity in this trait compared to metabolism. Our results suggest that plasticity of temperature limits and metabolism may benefit this species in variable environments such as those encountered in its expanded range. Lack of plasticity in water loss during resting and activity suggests that these frogs rely on their high cutaneous resistance and behavioural means to buffer climate variation. This study highlights the importance of synergistic interactions between physiology and behaviour in determining amphibian responses to temperature variation.

Similarity of Crocodilian and Avian Lungs Indicates Unidirectional Flow Is Ancestral for Archosaurs

Patterns of airflow and pulmonary anatomy were studied in the American alligator (Alligator mississippiensis), the black caiman (Melanosuchus niger), the spectacled caiman (Caiman crocodilus), the dwarf crocodile (Osteolaemus tetraspis), the saltwater crocodile (Crocodylus porosus), the Nile crocodile (Crocodylus niloticus), and Morelet's crocodile (Crocodylus moreletii). In addition, anatomy was studied in the Orinoco crocodile (Crocodylus intermedius). Airflow was measured using heated thermistor flow meters and visualized by endoscopy during insufflation of aerosolized propolene glycol and glycerol. Computed tomography and gross dissection were used to visualize the anatomy. In all species studied a bird-like pattern of unidirectional flow was present, in which air flowed caudad in the cervical ventral bronchus and its branches during both lung inflation and deflation and craniad in dorsobronchi and their branches. Tubular pathways connected the secondary bronchi to each other and allowed air to flow from the dorsobronchi into the ventrobronchi. No evidence for anatomical valves was found, suggesting that aerodynamic valves cause the unidirectional flow. In vivo data from the American alligator showed that unidirectional flow is present during periods of breath-holding (apnea) and is powered by the beating heart, suggesting that this pattern of flow harnesses the heart as a pump for air. Unidirectional flow may also facilitate washout of stale gases from the lung, reducing the cost of breathing, respiratory evaporative water loss, heat loss through the heat of vaporization, and facilitating crypsis. The similarity in structure and function of the bird lung with pulmonary anatomy of this broad range of crocodilian species indicates that a similar morphology and pattern of unidirectional flow were present in the lungs of the common ancestor of crocodilians and birds. These data suggest a paradigm shift is needed in our understanding of the evolution of this character. Although conventional wisdom is that unidirectional flow is important for the high activity and basal metabolic rates for which birds are renowned, the widespread occurrence of this pattern of flow in crocodilians indicates otherwise. Furthermore, these results show that air sacs are not requisite for unidirectional flow, and therefore raise questions about the function of avian air sacs.

Testing for relationships between individual crab behavior and metabolic rate across ecological contexts

Two classes of explanations for covariation between activity level and metabolic rate among conspecifics have been proposed. First, individual-level variation in activity exhibited during the measurement of metabolic rate should covary with routine metabolic rate because movement increases respiration (a methodological relationship). Second, energetic-based hypotheses posit relationships between individual activity measured under more natural conditions and baseline measures of metabolic rate, among other behavioral, physiological, and life-history traits (functional relationships). Here, we examined these potential relationships between individual behavior and metabolic rate in the mud crab (Panopeus herbstii). Specifically, we tested for (1) an effect of crab activity in metabolic chambers (activitychamber) on routine metabolic rate (RMR), and (2) an effect of crab activity in mesocosms that mimicked field conditions (activitymesocosm) on standard metabolic rate (SMR). To test for context dependence, we assessed both activity-metabolic rate relationships in the absence and presence of predation threat from toadfish (Opsanus tau) in the form of waterborne chemical cues. Individual variation in activitymesocosm and RMR was repeatable over time. In support of a methodological relationship, individual differences in RMR were partially explained by crab activitychamber. After accounting for this methodological relationship, individual SMR was inversely related to activitymesocosm, supporting an allocation model that predicts behavior and baseline metabolic rate compete for finite energy reserves. We found no evidence of context dependence in either activity-metabolic rate relationship. Thus, our study emphasizes the importance of considering methodological artifacts in elucidating functional relationships between individual behavior and energetics.

The cost of digestion in the fish-eating myotis (Myotis vivesi)

Flying vertebrates, such as bats, face special challenges with regards to the throughput and digestion of food. On the one hand, as potentially energy-limited organisms, bats must ingest and assimilate energy efficiently in order to satisfy high resting and active metabolic demands. On the other hand, the assimilation of nutrients must be accomplished using a digestive tract that is, compared with that of similarly sized non-flying vertebrates, significantly shorter. Despite these competing demands, and the relative breadth of dietary diversity among bats, little work has been done describing the cost of digestion, termed 'specific dynamic action' (SDA). Here, we provide the first systematic assessment of the SDA response in a bat, the fish-eating myotis (Myotis vivesi). Given the shorter digestive tract and the relatively higher resting and active metabolic rates of bats in general, and based on anecdotal published evidence, we hypothesized that the SDA response in fish-eating myotis would be dependent on meal size and both significantly more brief and intense than in small, non-flying mammals. In agreement with our hypothesis, we found that the peak metabolic rate during digestion, relative to rest, was significantly higher in these bats compared with any other mammals or vertebrates, except for some infrequently eating reptiles and amphibians. Additionally, we found that the magnitude and duration of the SDA response were related to meal size. However, we found that the duration of the SDA response, while generally similar to reported gut transit times in other small bats, was not substantially shorter than in similarly sized non-flying mammals.

A new method for resolving uncertainty of energy requirements in large water breathers: the ‘mega‐flume’ seagoing swim‐tunnel respirometer

Summary Body size is a key determinant of metabolic rate, but logistical constraints have led to a paucity of energetics measurements from large water‐breathing animals. As a result, estimating energy requirements of large fish generally relies on extrapolation of metabolic rate from individuals of lower body mass using allometric relationships that are notoriously variable. Swim‐tunnel respirometry is the ‘gold standard’ for measuring active metabolic rates in water‐breathing animals, yet previous data are entirely derived from body masses <10 kg – at least one order of magnitude lower than the body masses of many top‐order marine predators. Here, we describe the design and testing of a new method for measuring metabolic rates of large water‐breathing animals: a c. 26 000 L seagoing ‘mega‐flume’ swim‐tunnel respirometer. We measured the swimming metabolic rate of a 2·1‐m, 36‐kg zebra shark Stegostoma fasciatum within this new mega‐flume and compared the results to data we collected from other S. fasciatum (3·8–47·7 kg body mass) swimming in static respirometers and previously published measurements of active metabolic rate measurements from other shark species. The mega‐flume performed well during initial tests, with intra‐ and interspecific comparisons suggesting accurate metabolic rate measurements can be obtained with this new tool. Inclusion of our data showed that the scaling exponent of active metabolic rate with mass for sharks ranging from 0·13 to 47·7 kg was 0·79; a similar value to previous estimates for resting metabolic rates in smaller fishes. We describe the operation and usefulness of this new method in the context of our current uncertainties surrounding energy requirements of large water‐breathing animals. We also highlight the sensitivity of mass‐extrapolated energetic estimates in large aquatic animals and discuss the consequences for predicting ecosystem impacts such as trophic cascades.

Ocean acidification exacerbates the impacts of global warming on embryonic little skate, Leucoraja erinacea (Mitchill)

Ocean acidification and warming have the potential to profoundly impact marine fishes by reducing embryo fitness and survival. Local adaptation to thermal gradients may reduce the impact of global warming, but whether fish from different populations may respond differently to climatic stressors remains unknown. The hypothesis that acidification and warming may have an effect on development, aerobic scope, and survival was tested in little skate (Leucoraja erinacea) embryos from two latitudinally separated populations. Temperature had the strongest effect on development, survival and metabolic rates, but acidification further exacerbated stress on embryos from the Gulf of Maine population by increasing the costs of activity, development time, and reducing body condition of newly hatched skates. Active metabolic rates of both populations exhibited countergradient variation with peak of performance at 18°C, but were affected differently by acidification. These findings demonstrate that even adjacent fish populations may respond differently to increasing temperature and acidification and emphasize the need for multi-stressor studies on different populations of fishes with wide geographic range to understand complex responses to climate change and other environmental challenges.

Metabolic cold adaptation and aerobic performance of blue mussels (Mytilus edulis) along a temperature gradient into the High Arctic region

The blue mussel (Mytilus edulis) has recently expanded its northern distribution in the Arctic and is therefore considered to be a sensitive indicator of climate changes in this region. In this study, we compared aerobic performance of blue mussels from High Arctic, Subarctic and temperate populations at different temperatures. Standard metabolic rates (SMR) and active metabolic rates (AMR) were measured for each population, and absolute (AMR − SMR) and factorial ( $$\frac{AMR}{SMR}$$ ) scopes were calculated. Blue mussels from the temperate population had the lowest Q10 (= 1.8) and the largest thermal window (−1 to 25 °C), whereas Q10 values in the Arctic populations were 1.9 (Subarctic) and 2.3 (High Arctic), with a thermal window of −1 to 21 °C. Aerobic scope increased with rising temperatures, reaching a maximum at 14 °C (temperate) and 7 °C (Subarctic and High Arctic, respectively), after which a decrease was observed at temperatures exceeding 14 °C. At low temperatures (−1 °C), the average SMR of the High Arctic population was 93 % higher than that of the temperate population and 22 % higher than that of the Subarctic population. Combined, our results demonstrate physiological adaptation and plasticity of blue mussels across latitudes spanning from 56 to 77oN. This indicates that low ocean temperature per se does not constrain metabolic activity of Mytilus in the Arctic; rather, we speculate that maturation of reproductive tissues, larval supply and annual energy budgets are the most relevant factors influencing Mytilus populations near their northern distributional edge in the Arctic.

Acute effects of β-naphthoflavone on cardiorespiratory function and metabolism in adult zebrafish (Danio rerio).

Aryl hydrocarbon receptor (AhR) agonists are known to cause lethal cardiovascular deformities in fish after developmental exposure. Acute adult fish toxicity of AhR agonists is thought to be minimal, but limited evidence suggests sublethal effects may also involve the cardiac system in fish. In the present study, adult zebrafish (Danio rerio) were aqueously exposed to solvent control or three nominal concentrations of the commonly used model AhR agonist, β-naphthoflavone (BNF), for 48 h. Following exposure, fish were subjected to echocardiography to determine cardiac function or swimming tests with concurrent oxygen consumption measurement. Critical swimming speed and standard metabolic rate were not significantly changed, while active metabolic rate decreased with increasing BNF exposure, reaching statistical significance at the highest BNF exposure. Factorial aerobic scope was the most sensitive end-point and was decreased at even lower BNF concentrations, indicating a reduced aerobic capacity after acute AhR agonist exposure in adult fish. The highest BNF concentration caused a significant decrease in cardiac output, while increasing the ratio of atrial to ventricular heart rate (indicating atrioventricular conduction blockade). In conclusion, the effect of acute BNF exposure on zebrafish metabolic capacity and cardiac function is likely to be physiologically important given that fish have a critical need for adequate oxygen to fuel essential survival behaviors such as swimming, growth, and reproduction. Future studies should be directed at examining the effects of other polycyclic aromatic hydrocarbons on fish cardiorespiratory function to determine whether their effects and modes of action are similar to BNF.

Effects of temperature and digestion on the swimming performance of juvenile Chinese bream

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 21:183-189 (2014) - DOI: https://doi.org/10.3354/ab00584 Effects of temperature and digestion on the swimming performance of juvenile Chinese bream Jing Peng, Zhen-Dong Cao, Shi-Jian Fu* Laboratory of Evolutionary Physiology and Behaviour, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing 401331, PR China *Corresponding author: shijianfu9@hotmail.com ABSTRACT: Fish that are active foragers usually perform routine activities while digesting their food; thus, postprandial swimming capacity might be ecologically important. To test whether digestion affected swimming performance in an active forager and whether the possible effects varied with temperature, we investigated the critical swimming speed (Ucrit) and the resting and active metabolic rate (MO2) of fasted and fed juvenile Chinese bream Parabramis pekinensis after 30 d exposure to 3 temperatures (15, 20, and 25°C). In fasted fish, Ucrit, resting and active MO2 all increased with temperature. Digestion elicited a significant increase in MO2, which was enhanced at higher temperatures. Compared to fasted fish, fed fish exhibited significantly lower Ucrit in both the 25 and 20°C groups, whereas no significant difference in Ucrit was observed between fasted and fed fish in the 15°C group. Furthermore, digestion resulted in a significantly higher active MO2 in the 15°C group, whereas no significant difference in active MO2 was observed between fasted and fed fish in the 20 and 25°C groups. This suggests that the bream adopted an additive metabolic mode, i.e. digestion and swimming were performed independently at low temperatures, but shifted to a digestion-priority mode at higher temperatures due to a shortage of oxygen resulting from an increased digestive and locomotive oxygen demand. The present study contradicted our hypothesis that an active cyprinid with high swimming performance would give priority to locomotion when the oxygen supply was insufficient to meet the metabolic demands of both digestion and swimming. KEY WORDS: Digestion · Metabolic mode · Metabolic priority · Swimming performance · Temperature Full text in pdf format PreviousNextCite this article as: Peng J, Cao ZD, Fu SJ (2014) Effects of temperature and digestion on the swimming performance of juvenile Chinese bream. Aquat Biol 21:183-189. https://doi.org/10.3354/ab00584 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 21, No. 3. Online publication date: September 03, 2014 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2014 Inter-Research.

Predicting physical activity energy expenditure in manual wheelchair users.

This study aimed to assess the influence of anatomical placement of an accelerometer on physical activity energy expenditure prediction in manual wheelchair users. Ten accelerometer units (ActiGraph GT3X+) were attached to a multiaxis shaker table and subjected to a sinusoidal oscillation procedure to assess mechanical validity and reliability. Fifteen manual wheelchair users (mean ± SD: age, 36 ± 11 yr; body mass, 70 ± 12 kg) then completed five activities, including desk work and wheelchair propulsion (2, 4, 6, and 8 km·h). Expired gases were collected throughout. GT3X+ accelerometers were worn on the right wrist, upper arm, and waist. The relations between physical activity counts and metabolic rate were subsequently assessed, and bias ± 95% limits of agreement was calculated. During mechanical testing, coefficients of variation ranged from 0.2% to 4.7% (intraunit) and 0.9% to 5.2% (interunit) in all axes. During human exercise testing, physical activity counts at each anatomical location was significantly (P < 0.01) correlated with metabolic rate (wrist, r = 0.93; upper arm, r = 0.87; waist, r = 0.73). The SEE for each correlation were 3.34, 4.38, and 6.07 kJ·min for the wrist, upper arm, and waist, respectively. The absolute bias ± 95% limits of agreement values were 0.0 ± 6.5 kJ·min, 0.0 ± 8.5 kJ·min, and 0.0 ± 11.8 kJ·min for the wrist, upper arm, and waist, respectively. The ActiGraph GT3X+ is a reliable tool for determining mechanical movements within the physiological range of human movement. Of the three anatomical locations considered, a wrist-mounted accelerometer explains more of the variance and results in the lowest random error when predicting physical activity energy expenditure in manual wheelchair users.

Overinflated behavioural energetics: using dynamic body acceleration to accurately measure behaviour duration and estimate energy expenditure

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 21:121-126 (2014) - DOI: https://doi.org/10.3354/ab00574 NOTE Overinflated behavioural energetics: using dynamic body acceleration to accurately measure behaviour duration and estimate energy expenditure Anthony A. Robson1,2,*, Robert P. Mansfield2 1LabexMER, UMS 3113 CNRS, Institut Universitaire Européen de la Mer, Université de Brest, Rue Dumont D’Urville, 29280 Plouzané, France 2Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK *Corresponding author: a.a.robson@outlook.com ABSTRACT: Data loggers that measure acceleration are regularly used to quantify the behavioural energetics of animals. Calculating dynamic body acceleration (DBA) by smoothing acceleration data using a necessarily long-running mean of e.g. ≥1 s (the DBA method) is not appropriate for determining behaviour duration. In fact, the DBA method results in the elongation of behaviour durations (mean ± 95% CI behaviour duration elongation for scallops [n = 10 animals] and humans [n = 10 free-ranging aquatic biologists]: 508.5 ± 277.2 and 19.3 ± 1.1%, respectively) and consequently an overestimation of energy expenditure (mean ± 95% CI activity metabolic rate overestimation: 212.5 ± 48.0 and 6.12 ± 0.34%, for scallops and humans, respectively; overall metabolic rate overestimation: 91.1 ± 29.9 and 4.18 ± 0.20%, for scallops and humans, respectively). Behaviour duration elongation is of greatest significance when behaviour durations are short (minimum, mean and maximum single behaviour duration for scallops and humans recorded in this study: 0.12 and 0.37, 0.40 and 8.04, 0.84 and 185.73 s, respectively). Overestimation of the duration of behaviours naturally causes errors in the calculations of behavioural time–energy budgets for all species that move intermittently, as demonstrated for scallops, crabs, ‘amphibious’ signal crayfish and humans. Furthermore, behaviours of any duration should be accurately detected, quantified and when appropriate, the behaviour type should be identified. The R package BEnergetix can quickly calculate accurate invertebrate and vertebrate behavioural time-energy budgets from acceleration, metabolic rate and environmental data. KEY WORDS: Behaviour · Activity · Energy expenditure · Ecology · Accelerometer · Accuracy · R package · Crayfish · Scallop · Crab · Human Full text in pdf format Supplementary material PreviousNextCite this article as: Robson AA, Mansfield RP (2014) Overinflated behavioural energetics: using dynamic body acceleration to accurately measure behaviour duration and estimate energy expenditure. Aquat Biol 21:121-126. https://doi.org/10.3354/ab00574 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 21, No. 2. Online publication date: July 03, 2014 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2014 Inter-Research.

Diurnal and water salinity-dependent metabolic activity of juvenile white steenbras Lithognathus lithognathus

The euryhaline white steenbras Lithognathus lithognathus is an important estuarine-dependent fish species in the South African marine and estuarine environment. Its tolerance to water quality fluctuations, in particular its metabolic rate responses to salinity changes, has not been studied. In order to contribute to ecophysiogical data on this species, oxygen consumption by white steenbras was determined to quantify metabolic activity. White steenbras were most active during daylight hours when oxygen consumption was 28% higher than during the scotophase. Standard, routine and active metabolic rate estimates were 0.04, 0.09 and 0.12 mg O2 g−1 h−1, respectively. In juveniles (body mass [W] = 19.8–85 g fish−1), the metabolic rate (MR; mg O2 g−1 h−1) was estimated as MR = 0.62W−0.526. The MR was reduced in fish exposed to a fast drop in salinity within 10 min from 35 to 5, but not in fish exposed to a fast drop to 25 or a slow drop within 3 or 9 h to 25 or 5, respectively. At a salinity of 5, oxygen consumption rate was 51% lower than at salinities of 25 and 35.

Impact of an Acute Sublethal Exposure of Endosulfan on Early Juvenile Lobster (Homarus americanus)

Anthropogenic chemicals in the environment during critical periods could potentially affect the physiology of the economically valuable American lobster ( Homarus americanus ). Endosulfan (Thiodan™ WP) is a broad-spectrum organochlorine insecticide widely used in agricultural areas in Canada that significantly affects survival and growth of lobster larvae based on acute exposure studies. To detect more subtle physiological effects of an acute (96-h) sub-lethal level (0.1 μg·L -1 ) of formulated endosulfan exposure on early juvenile lobsters, investigations of metabolic rates, growth and the tissue structure of the hepatopancreas were conducted on animals that molted following the exposure. The standard and active metabolic rates were not significantly affected, but their differential, defined as the metabolic scope (MS) was significantly decreased by 25% for exposed animals. Lobster growth and survival were not affected. For the exposed lobsters, minor alterations of the digestive cell structures were observed. These results suggest that the decrease in MS for exposed juvenile lobsters could have consequences in terms of survival in the wild by impairing their abilities to find a shelter, food or protect themselves from predators. The growth and survival in laboratory conditions suggests that lobsters may adjust their metabolism to pesticide exposure by maintaining a positive energy balance with some compensatory mechanisms; however, this may not be possible in their natural environment. This study suggests that conclusions based solely on lethal toxicity assays could be misleading for sublethal effects of contaminants on marine organisms, which could be investigated more thoroughly using an integrated approach based on physiological indicators.

Dietary selenomethionine exposure alters swimming performance, metabolic capacity and energy homeostasis in juvenile fathead minnow

Selenium (Se) is known to cause chronic toxicity in aquatic species. In particular, dietary exposure of fish to selenomethionine (SeMet), the primary form of Se in the diet, is of concern. Recent studies suggest that chronic exposure to elevated dietary SeMet alters energy and endocrine homeostasis in adult fish. However, little is known about the direct effects of dietary SeMet exposure in juvenile fish. The objective of the present study was to investigate sublethal physiological effects of dietary SeMet exposure in juvenile fathead minnow (Pimephales promelas). Twenty days-post-hatch fathead minnow were exposed for 60 days to different measured concentrations (2.8, 5.4, 9.9, 26.5μgSe/g dry mass [dm]) of Se in food in the form of SeMet. After exposure, samples were collected for Se analysis and fish were subjected to a swimming performance challenge to assess critical swim speed (Ucrit), tail beat frequency and tail beat amplitude, oxygen consumption (MO2), cost of transport (COT), standard metabolic rate (SMR), active metabolic rate (AMR), and factorial aerobic scope (F-AS). Ucrit was decreased in the 26.5μgSe/gdm exposure group compared to the control group. Tail beat frequency and tail beat amplitude were significantly reduced in fish fed 9.9 and 26.5μgSe/g. An increase in MO2 and COT was observed in the 9.9 and 26.5μgSe/g exposure groups compared to the control group. While the AMR of the high dose group was increased relative to control, there were no significant differences in SMR and F-AS. Energy storage capacity was measured via whole body triglyceride and glycogen concentrations. Triglyceride concentrations in non-swam fish were elevated in the 5.4μgSe/g group relative to controls. Fatigued (swam) fish had significantly lower whole body triglycerides than non-swam fish. All non-swam SeMet exposure groups had significantly decreased whole body glycogen concentrations compared to controls, while the 5.4 and 26.5μgSe/g exposure groups had significantly greater whole body glycogen concentrations in swam versus non-swam fish. A decrease in whole body cortisol was observed in swam fish in the 5.4μgSe/g exposure group compared to control fish. Whole body cortisol was greater in control, 9.9 and 26.5μgSe/g swam fish compared to non-swam fish. These results suggest that exposure to environmentally relevant concentrations of dietary SeMet impairs swimming performance, aerobic capacity, and energy homeostasis, potentially impacting survivability of juvenile fish in Se impacted aquatic ecosystems.

Effect of temperature and dissolved oxygen on swimming performance in crucian carp

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 21:57-65 (2014) - DOI: https://doi.org/10.3354/ab00571 Effect of temperature and dissolved oxygen on swimming performance in crucian carp Liu-Yi Penghan, Zhen-Dong Cao, Shi-Jian Fu* Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing 400047, PRChina *Corresponding author: shijianfu9@hotmail.com ABSTRACT: Changing environmental conditions may affect the swimming performance of fish by affecting energy sources through changes in temperature and concentration of dissolved oxygen (DO). It has become increasingly important to investigate the effect of temperature and DO on the swimming performance of fish species as hypoxia in aquatic environments worldwide is increasing due to the effects of anthropogenic global warming. To test how different swimming modes respond to thermal and DO changes, 3 measures of swimming performance were tested: critical swimming speed (Ucrit), constant acceleration speed (Ucat), and maximum speed during a fast-start (Ufast). The changes in these 3 aspects of swimming performance in juvenile crucian carp Carassius carassius were quantified at 2 different temperatures (10 and 20°C) and 3 different DO concentrations (2.5, 5, and 9 mg l-1). Ucat was ca. 110 to 156% of Ucrit, whereas Ufast was ca. 394 to 472% of Ucrit, depending on the experimental conditions. Temperature had a significant effect on all 3 measures of swimming performance, whereas DO had significant effects only on Ucat and Ucrit (Ucrit but not Ucat decreased in the 2.5 mg l-1 DO group). The active metabolic rate (MO2active) under the different experimental conditions suggested that the decrease in Ucrit at a lower temperature and DO level could be partially explained by a decrease in oxygen uptake capacity. These results indicate that all 3 swimming measurements should be used when addressing how temperature affects swimming performance. KEY WORDS: Aerobic and anaerobic locomotion · Constant acceleration speed · Critical swimming speed · Crucian carp · Environmental condition · Fast-start swimming performance · Swimming performance Full text in pdf format PreviousNextCite this article as: Penghan LY, Cao ZD, Fu SJ (2014) Effect of temperature and dissolved oxygen on swimming performance in crucian carp. Aquat Biol 21:57-65. https://doi.org/10.3354/ab00571 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 21, No. 1. Online publication date: June 18, 2014 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2014 Inter-Research.

Loss of SLN‐mediated thermogenesis is compensated by increased brown adipose tissue activity (1105.4)

Thermogenic processes are critical contributors to body temperature maintenance and, when activated, are major components of metabolism. Elucidating the mechanisms that contribute to thermogenesis is of increasing importance as they can provide targets to combat the rising obesity epidemic. We recently identified Sarcolipin (SLN), a regulator of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) in skeletal muscle, as a significant contributor to metabolism and cold‐induced thermogenesis during an acute cold challenge. However, acute cold exposure does not allow for a detailed study of the physiological and molecular mechanisms involved. Thus, to further detail the role of SLN in thermogenesis, we challenged wild‐type (WT) and SLN‐knockout (SLN‐KO) mice to a long‐term cold exposure. SLN‐KO mice can adapt to gradual cold exposure and maintain normal core body temperature. However, SLN‐KO mice exhibit increased oxygen consumption compared to WT littermates and have greater physical activity and food intake. Histological examination of brown adipose (BAT) and inguinal fat depots showed increased depletion of fat stores from cold‐adapted SLN‐KO mice, and protein analysis showed increased UCP1 expression. These data show that SLN‐KO mice must significantly increase BAT activity and browning of white fat in order to compensate for the loss of SLN‐mediated thermogenesis. Increased physical activity, food intake, and elevated metabolic rate suggest a reliance on less efficient thermogenic mechanisms. Thus, an absence of SLN increases the energetic cost of survival in a cold environment. These data demonstrate that a combination of BAT and SLN‐based thermogenesis is necessary for survival in a cold environment and are integral components of energetic homeostasis.

Allometric relationship between body mass and aerobic metabolism in zebrafish Danio rerio

The relationship between body mass (M) and metabolic rate was investigated through the assessment of active (R(A)) and standard (R(S)) metabolic rate at different life stages in zebrafish Danio rerio (5 day-old larvae, 2 month-old juveniles and 6 month-old adults). Scaling exponents and constants were assessed for standard (R(S) = 0·273M(0·965) in mgO(2) g(-1) h(-1)) and active metabolic rate (R(A) = 0·799M(0·926) in mgO(2) g(-1) h(-1)). These data provide the basis for further experiments regarding the effects of environmental factors on aerobic metabolism throughout the life cycle of this species.

Heritable variation in reaction norms of metabolism and activity across temperatures in a wild-derived population of white-footed mice (Peromyscus leucopus)

Heritable variation in metabolic traits is likely to affect fitness. In this study, white-footed mice from wild-derived photoresponsive [R, infertile in short day length (SD)] and non-photoresponsive (NR, fertile in SD) selection lines were maintained under short-day (SD 8Light:16Dark), sub-thermoneutral conditions (22 or 12°C). Mice had significantly higher levels of food intake and resting metabolic rates (RMR) at low temperature. RMR differed significantly between lines (greater in NR mice). In contrast to previous work under thermoneutral conditions, there was no significant difference in overall activity or average daily metabolic rates (ADMR) of mice from the two lines. Reduced activity may reflect behavioral changes under cooler conditions (e.g., nest building) reducing the overall energetic cost of fertility (for NR mice). There was no significant difference in maximal rate of oxygen consumption ([Formula: see text]) between lines. R mice had significantly greater brown adipose tissue and white abdominal fat mass due to both line and temperature. Reaction norms for intake, resting metabolism (RMR/BMR) and level of activity from current (12 and 22°C) and previously published data (28°C) demonstrate independent effects of genetics (line) and environment (temperature) for resting metabolism, but a clear interaction between these for activity. The results suggest that fertility under winter conditions imposes metabolic costs that are related to the level of reproductive development. Under the coldest conditions tested, however, mice that remained fertile in SD reduced activity, ADMR and food requirements, decreasing the differential between selection lines. Heritable variation in reaction norms suggests a genetic by environment effect that could be subject to selection.

The effects of fasting on swimming performance in juvenile qingbo (Spinibarbus sinensis) at two temperatures

We measured the following variables to investigate the effects of fasting and temperature on swimming performance in juvenile qingbo (Spinibarbus sinensis): the critical swimming speed (Ucrit), resting metabolic rate (ṀO2rest) and active metabolic rate (ṀO2active) of fish fasting for 0 (control), 1, 2 and 4 weeks at low and high acclimation temperatures (15 and 25°C). Both fasting treatment and temperature acclimation had significant effects on all parameters measured (P<0.05). Fasting at the higher temperature had a negative effect on all measured parameters after 1 week (P<0.05). However, when acclimated to the lower temperature, fasting had a negative effect on Ucrit until week 2 and on (ṀO2rest), (ṀO2active) and metabolic scope (MS, (ṀO2active)–(ṀO2rest)) until week 4 (P<0.05). The values of all parameters at the lower temperature were significantly lower than those at the higher temperature in the identical fasting period groups except for (ṀO2rest) of the fish that fasted for 2 weeks. The relationship between fasting time (T) and Ucrit was described as Ucrit(15)=−0.302T2−0.800T+35.877 (r=0.781, n=32, P<0.001) and Ucrit(25)=0.471T2−3.781T+50.097 (r=0.766, n=32, P<0.001) at 15 and 25°C, respectively. The swimming performance showed less decrease in the early stage of fasting but more decrease in the later stage at the low temperature compared to the high temperature, which might be related to thermal acclimation time, resting metabolism, respiratory capacity, energy stores, enzyme activity in muscle tissue and energy substrate utilization changes with fasting between low and high temperatures. The divergent response of the swimming performance to fasting in qingbo at different temperatures might be an adaptive strategy to seasonal temperature and food resource variation in their habitat.

A Field Study of Experimental of Radiant Cooling for Residential Building in a Tropical Climate

This paper presents an experimental study of radiant cooling for building air-conditioning in a tropical climate. To prevent condensation of moisture on the cooling panel, the temperature of chilled water supplied to the panel was limited. This led to the limitations of heat extraction capacity at the panel and its application to only space with low thermal load and low metabolic rate activity of people in the space. In addition to compare energy saving of radiant cooling system and air conditioning which the result of this paper the radiant cooling system can be used to achieve70% for energy saving. 