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Acclimation Temperature (acclimation + temperature)
Selected AbstractsDevelopment and application of a species sensitivity distribution for temperature-induced mortality in the aquatic environmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2008Pepijn de Vries Abstract Current European legislation has static water quality objectives for temperature effects, based on the most sensitive species. In the present study a species sensitivity distribution (SSD) for elevated temperatures is developed on the basis of temperature sensitivity data (mortality) of 50 aquatic species. The SSD applies to risk assessment of heat discharges that are localized in space or time. As collected median lethal temperatures (LT50 values) for different species depend on the acclimation temperature, the SSD is also a function of the acclimation temperature. Data from a thermal discharge in The Netherlands are used to show the applicability of the developed SSD in environmental risk assessment. Although restrictions exist in the application of the developed SSD, it is concluded that the SSD approach can be applied to assess the effects of elevated temperature. Application of the concept of SSD to temperature changes allows harmonization of environmental risk assessment for stressors in the aquatic environment. When a synchronization of the assessment methods is achieved, the steps to integration of risks from toxic and nontoxic stressors can be made. [source] Inaccurate or disparate temperature cues?FUNCTIONAL ECOLOGY, Issue 5 2010Seasonal acclimation of terrestrial, aquatic locomotor capacity in newts Summary 1.,Many organisms respond to seasonal temperature fluctuations by the reversible modification of whole-animal performance. Semiaquatic ectotherms, which possess this acclimatory capacity in swimming speed, lack the plastic response in terrestrial locomotor performance and vice versa. Theory predicts that the presence of reversible (seasonal) thermal acclimation or fixed phenotypes depends on the predictability of future thermal conditions (i.e. accuracy of temperature cues) in a given environment. Alternatively, comparative data suggest that thermal acclimation is induced by disparate temperature cues in water and on land. 2.,We tested both predictions by examining the seasonal acclimation response in thermal sensitivity of maximal swimming and running speed in adult alpine newts, Ichthyosaura (formerly Triturus) alpestris. 3.,Following the seasonal variation in environmental temperatures, we exposed newts to 5 °C from November to March and, after a gradual temperature increase, to either a constant (15 °C) or fluctuating (10,20 °C) thermal regime from May to June. At the end of each treatment, we measured newt swimming and running capacity at five temperatures (range 5,25 °C). In the field, hourly temperatures were recorded in various aquatic and terrestrial microhabitats to obtain information about the predictability of thermal conditions in both environments. 4.,Seasonal acclimation shaped the thermal sensitivity of swimming speed under both constant and fluctuating temperature treatments. Thermal sensitivity of running speed was markedly modified by a fluctuating thermal regime so that newts ran at the highest test temperature faster than cold-acclimated individuals. Natural thermal environment contained a similar proportion of predictable variation in water and on land. 5.,Complex seasonal acclimation of locomotor capacity in newts was influenced by the disparate thermal cues, i.e. mean acclimation temperature or diel temperature fluctuations, rather than by the different accuracy of these cues in water and on land. Future confrontations of theory with empirical data will require more attention not only on the assumptions of adaptive thermal acclimation but also on the ecologically relevant thermal conditions during acclimation experiments. [source] Allometric scaling of maximum metabolic rate: the influence of temperatureFUNCTIONAL ECOLOGY, Issue 4 2008C. R. White Summary 1Maximum aerobic metabolic rate, measured in terms of rate of oxygen consumption during exercise (), is well known to scale to body mass (M) with an exponent greater than the value of 0·75 predicted by models based on the geometry of systems that supply nutrients. 2Recently, the observed scaling for (,M0·872) has been hypothesized to arise because of the temperature dependence of biological processes, and because large species show a greater increase in muscle temperature when exercising than do small species. 3Based on this hypothesis, we predicted that will be positively related to ambient temperature, because heat loss is restricted at high temperatures and body temperature is likely to be elevated to a greater extent than during exercise in the cold. 4This prediction was tested using a comparative phylogenetic generalized least-squares (PGLS) approach, and 34 measurements of six species of rodent (20·5,939 g) maximally exercising at temperatures from ,16 to 30 °C. 5 is unrelated to testing temperature, but is negatively related to acclimation temperature. We conclude that prolonged cold exposure increases exercise-induced by acting as a form of aerobic training in mammals, and that elevated muscle temperatures of large species do not explain the scaling of across taxa. [source] White muscle 20S proteasome activity is negatively correlated to growth rate at low temperature in the spotted wolffish Anarhichas minorJOURNAL OF FISH BIOLOGY, Issue 7 2010S. G. Lamarre The effect of temperature and mass on specific growth rate (G) was examined in spotted wolffish Anarhichas minor of different size classes (ranging from 60 to 1500 g) acclimated at different temperatures (4, 8 and 12° C). The relationship between G and 20S proteasome activity in heart ventricle, liver and white muscle tissue was then assessed in fish acclimated at 4 and 12° C to determine if protein degradation via the proteasome pathway could be imposing a limitation on somatic growth. Cardiac 20S proteasome activity was not affected by acclimation temperature nor fish mass and had no correlation with G. Hepatic 20S proteasome activity was higher at 12° C but did not show any relationship with G. Partial correlation analysis showed that white muscle 20S proteasome activity was negatively correlated to G (partial Pearson's r = ,0·609) but only at cold acclimation temperature (4° C). It is suggested that acclimation to cold temperature involves compensation of the mitochondrial oxidative capacity which would in turn lead to increased production of oxidatively damaged proteins that are degraded by the proteasome pathway and ultimately negatively affects G at cold temperature. [source] The hypoxic threshold for maximum cardiac performance in rainbow trout Oncorhynchus mykiss (Walbaum) during simulated exercise conditions at 18° CJOURNAL OF FISH BIOLOGY, Issue 3 2007L. M. Hanson Perfused rainbow trout Oncorhynchus mykiss hearts exposed to simulated exercise conditions (hypoxia, hyperkalemia and acidosis) at 18° C experienced complete failure of maximum cardiac performance at oxygen tensions <5·6 kPa and partial failure at <6·7 kPa. This hypoxic threshold, which occurred in the presence of maximal adrenergic stimulation (500 nM adrenaline), is unusually high compared with previous results at a colder acclimation temperature. Cardiac failure was primarily due to significant decreases (P < 0·05) in heart rate rather than cardiac stroke volume at all hypoxia levels tested. [source] Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperatureJOURNAL OF FISH BIOLOGY, Issue 1 2005P. L. M. Van Dijk The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three-fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding. [source] Frost tolerance in excised leaves of the common bugle (Ajuga reptans L.) correlates positively with the concentrations of raffinose family oligosaccharides (RFOs)PLANT CELL & ENVIRONMENT, Issue 8 2009SHAUN PETERS ABSTRACT Mass increases in raffinose family oligosaccharides (RFOs, ,1,6-galactosyl extensions of sucrose) are well documented in the generative tissues of many plants upon cold acclimation, and they (i.e. mainly the two shortest RFO members, raffinose and stachyose) have been suggested as frost stress protectants. Our focus here was on the longer RFO members as they commonly occur in the frost-hardy evergreen labiate Ajuga reptans in its natural habitat, and accumulate to their highest concentrations in winter when the plant is faced with sub-zero temperatures. We examined the effects of RFO concentration and chain length on frost tolerance using excised leaves which accumulate long-chain RFOs under both cold and warm conditions, thereby uncoupling the acclimation temperature from RFO production. We demonstrated that frost tolerance in excised A. reptans leaves correlates positively with long-chain RFO accumulation under both acclimation temperatures. After 24 d post-excision in the warm, the leaves had increased their RFO concentrations (mainly long-chain RFOs) 22-fold to 78 mg g,1 fresh weight, and decreased their EL50 values (temperature at which 50% leakage occurred) from ,10.5 to ,24.5 °C, suggesting a protective role for these oligosaccharides in the natural frost tolerance of A. reptans. [source] Effects of air exposure on the lysosomal membrane stability of haemocytes in blacklip abalone, Haliotis rubra (Leach)AQUACULTURE RESEARCH, Issue 3 2007Liang Song Abstract The neutral red retention (NRR) assay was used to evaluate the effects of air exposure on lysosomal membrane integrity in the haemolymph of blacklip abalone, Haliotis rubra, and its subsequent recovery in water. After acclimation in 16°C water for 7 days, abalone were exposed to an air temperature of 7, 16 or 23°C for 12 h in the air exposure experiment or to these three air temperatures, e.g., for 12, 24 or 36 h, followed by re-immersion in 16°C water in the lysosomal membrane stability recovery experiment. Statistical analyses of the air exposure experiment showed that when abalone were exposed to different air temperatures (7, 16 or 23°C), the lysosomal membrane stability was significantly affected by the air temperature, the exposure duration and their interaction. Air temperature similar to the acclimation temperature had a significantly lower impact on the lysosomal membrane stability within the initial 4.5 h in comparison with the other two temperatures in the same period. The lysosomal membrane stability recovery experiment showed that after air exposure durations of 12, 24 or 36 h, the re-stabilization of the lysosomal membrane was faster in the animals exposed to lower temperatures than those exposed to higher temperatures. The recovery of the lysosomal membrane stability in abalone exposed to lower 7°C air temperature was not significantly affected (F2, 66=0.251, P=0.779) by the exposure durations (12, 24 and 36 h) used in this study. Alternatively, the lysosomal membrane stability in abalone exposed to higher air temperatures of 16 or 23°C recovered at a faster rate when subjected to shorter durations of air exposure (F2, 66=3.663, P=0.031 and F1, 44=17.057, P<0.001 for 16 and 23°C respectively). [source] Cold tolerance of the banana prawn Penaeus merguiensis de Man and its growth at different temperaturesAQUACULTURE RESEARCH, Issue 1 2002Tung Hoang Abstract Critical thermal minima (CTMin) were determined for subadults of Penaeus merguiensis acclimated at 15, 18, 21 and 24 °C for 3 weeks. The effect of cooling rate on CTMin was also investigated. The CTMin of prawns from these respective acclimation groups were 5.3, 6.0, 7.4, 9.0 and 4.7, 5.4, 6.0, 7.3 °C at the cooling rate of 1 °C h,1 and 3 °C h,1 respectively. Both acclimation temperature and cooling rate had a significant effect (P < 0.01) on the CTMin. Observation during the acclimation period showed that the growth rate of prawns acclimated at 24 °C was much higher than those acclimated at 21, 18 and 15 °C. The results indicate that P. merguiensis can overwinter in aquaculture ponds in south-east Queensland, Australia, or other subtropical areas and attain good growth if simple overwintering facilities are available. [source] Maximized PUFA measurements improve insight in changes in fatty acid composition in response to temperatureARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009Coby van Dooremalen Abstract A general mechanism underlying the response of ectotherms to environmental changes often involves changes in fatty acid composition. Theory predicts that a decrease in temperature causes an increase in unsaturation of fatty acids, with an important role for long-chain poly-unsaturated fatty acids (PUFAs). However, PUFAs are particularly unstable and susceptible to peroxidation, hence subtle differences in fatty acid composition can be challenging to detect. We determined the fatty acid composition in springtail (Collembola) in response to two temperatures (5°C and 25°C). First, we tested different sample preparation methods to maximize PUFAs. Treatments consisted of different solvents for primary lipid extraction, mixing with antioxidant, flushing with inert gas, and using different temperature exposures during saponification. Especially slow saponification at low temperature (90,min at 70°C) in combination with replacement of headspace air with nitrogen during saponification and methylation maximized PUFAs for GC analysis. Applying these methods to measure thermal responses in fatty acid composition, the data showed that the (maximized) proportion of C20 PUFAs increased at low acclimation temperature. However, C18 PUFAs increased at high acclimation temperature, which is contrary to expectations. Our study illustrates that PUFA levels in lipids may often be underestimated and this may hamper a correct interpretation of differential responses of fatty acid composition. © 2009 Wiley Periodicals, Inc. [source] The influence of thermal parameters on the acclimation responses of pinfish Lagodon rhomboides exposed to static and decreasing low temperaturesJOURNAL OF FISH BIOLOGY, Issue 3 2007C. M. Reber Pinfish Lagodon rhomboides acclimation rates were determined by modelling changes in critical thermal minimum (Tcrit min, ° C) estimates at set intervals following a temperature decrease of 3,4° C. The results showed that pinfish gained a total of 3·7° C of cold tolerance over a range of acclimation temperatures (Tacc, ° C) from (23,12° C), that cold tolerance increased with exposure time to the reduced temperature at all Tacc, but that the rate of cold tolerance accruement (mean 0·14° C day,1) was independent of Tacc. A highly significant (P < 0·001) multivariate predictive model was generated that described the acclimation rates and thermal tolerance of pinfish exposed to reduction in water temperature: log10Tcrit min= 0·41597 , 0·01704Tacc+ 0·04320Tplunge, 0·08376[log10 (t+ 1)], where Tplunge is plunge temperature (° C) and t is the time (days). A comparison of the present data, with acclimation rate data for other species, suggests that factors such as latitude or geographic range may play a more important role than ambient temperature in determining cold acclimation rates in fishes. [source] Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperatureJOURNAL OF FISH BIOLOGY, Issue 1 2005P. L. M. Van Dijk The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three-fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding. [source] Physiology of diapause and cold hardiness in overwintering pupae of the apple leaf miner Phyllonorycter ringoniella in JapanPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2002Yi-Ping Li Abstract The apple leaf miner Phyllonorycter ringoniella (Matsumura) (Lepidoptera: Gracillariidae) overwinters as a diapausing pupa. The diapause rate reaches 100% in early October. Diapause intensity decreases gradually from early October and diapause terminates in early February. The fresh body weight of diapausing pupae is 1.6 times that of non-diapausing pupae. The main cryoprotectant in P. ringoniella pupae is trehalose. Three stages are distinguishable as indicated by the correlations between diapause intensity, levels of cold hardiness and the trehalose content: diapause induction occurred in October, diapause development from November to December, and post-diapause quiescence from January to April. During diapause induction, the pupae accumulate low levels of trehalose and do not survive exposure to ,15 °C. During diapause development, the pupae gradually accumulate more trehalose and show some ability to survive exposure to ,15 °C, but not to ,20 °C. During post-diapause quiescence, the pupae accumulate relatively more trehalose and cold hardiness fully develops, but decreases quickly in April. The trehalose content in pupae sampled in December is unaffected by acclimation temperatures in the range 0,30 °C, but decreases in pupae sampled in March after acclimation at temperatures from 5 to 15 °C. These results suggest that overwintering pupae of P. ringoniella have the ability to accumulate trehalose and develop a high level of cold hardiness during diapause development. [source] Frost tolerance in excised leaves of the common bugle (Ajuga reptans L.) correlates positively with the concentrations of raffinose family oligosaccharides (RFOs)PLANT CELL & ENVIRONMENT, Issue 8 2009SHAUN PETERS ABSTRACT Mass increases in raffinose family oligosaccharides (RFOs, ,1,6-galactosyl extensions of sucrose) are well documented in the generative tissues of many plants upon cold acclimation, and they (i.e. mainly the two shortest RFO members, raffinose and stachyose) have been suggested as frost stress protectants. Our focus here was on the longer RFO members as they commonly occur in the frost-hardy evergreen labiate Ajuga reptans in its natural habitat, and accumulate to their highest concentrations in winter when the plant is faced with sub-zero temperatures. We examined the effects of RFO concentration and chain length on frost tolerance using excised leaves which accumulate long-chain RFOs under both cold and warm conditions, thereby uncoupling the acclimation temperature from RFO production. We demonstrated that frost tolerance in excised A. reptans leaves correlates positively with long-chain RFO accumulation under both acclimation temperatures. After 24 d post-excision in the warm, the leaves had increased their RFO concentrations (mainly long-chain RFOs) 22-fold to 78 mg g,1 fresh weight, and decreased their EL50 values (temperature at which 50% leakage occurred) from ,10.5 to ,24.5 °C, suggesting a protective role for these oligosaccharides in the natural frost tolerance of A. reptans. [source] | |||||||||||||