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1.
Mikko Nikinmaa Heikki Tuurala Antti Soivio 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1980,140(3):255-260
Summary The blood oxygen binding properties and gill secondary lamellar structure of rainbow trout acclimated to several temperatures were studied. The blood oxygen carrying capacity decreased as acclimation temperature increased from 2 to 15 °C; the decrease was probably caused by an increase in plasma volume. Also the blood oxygen affinity decreased as the acclimation temperature increased from 2 to 15 °C. This change had no effect on the oxygen loading in gills, since the efferent arterial oxygen tension was adequate for approximately 100% erythrocytic O2 saturation at all acclimation temperatures, but facilitated the oxygen unloading in tissues. At the highest acclimation temperature (18 °C) the oxygen loading in gills was facilitated by the changes in the secondary lamellar structure; the proportion of erythrocytes in the secondary lamellar capillaries was higher than at the other acclimation temperatures (2 and 10 °C). 相似文献
2.
Peter C. Gehrke Donald R. Fielder 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):771-782
Summary Heart, ventilation and oxygen consumption rates ofLeiopotherapon unicolor were studied at temperatures ranging from 5 to 35°C, and during progressive hypoxia from 100% to 5% oxygen saturation. Biopotentials recorded from the water surrounding the fish corresponded to ventilation movements, and are thought to originate from the ventilatory musculature. Cardio-respiratory responses to temperature and dissolved oxygen follow the typical teleost pattern, with bradycardia, increased ventilation rate and reduced oxygen consumption occurring during hypoxia. However, ventilation rate did not increase at 15°C and below. Ventilation rate showed a slower response to increasing temperature (normoxic Q10=1.39) than heart rate and oxygen consumption (normoxic Q10=2.85 and 2.38).L. unicolor is unable to survive prolonged hypoxia by utilising anaerobic metabolism, but has a large gill surface area which presumably facilitates oxygen uptake in hypoxic environments. Periodic ventilation during normoxia in restingL. unicolor may improve ventilation efficiency by increasing the oxygen diffusion gradient across the gills.Abbreviations
EBG
electrobranchiogram
-
ECG
electrocardiogram 相似文献
3.
Synopsis The cichlid fish, Oreochromis mossambicus, was acclimated to 25°C for a 14 day period and then subjected to elevated temperatures of 30, 35, 40 and 45° C. Gill epithelia was progressively damaged from 30–40° C; gills from fish tested at 45°C showed less damage than those tested at 40°C. This is presumably due to the shorter exposure (survival) time at 45°C. Shrinkage of the secondary lamellae and the collapse of pillar cells supports the hypothesis that hypoxia at elevated temperatures is partially a function of changes in gill morphology. 相似文献
4.
Elizabeth L. Shimps Jason A. Osborne 《Journal of experimental marine biology and ecology》2005,325(2):146-162
Hypoxia events, or low dissolved oxygen (DO) conditions, occur frequently in North Carolina estuaries during the summer. These events may have harmful effects on important fish stocks, including spot (Leiostomus xanthurus) and Atlantic menhaden (Brevoortia tyrannus), but their consequences are not well understood. We investigated direct mortality due to hypoxia in juvenile spot and Atlantic menhaden to determine how the extent of mortality varies with the severity of hypoxia and the duration of exposure, and to explore how vulnerability to hypoxia changes across species, fish size, and temperature.Atlantic menhaden and spot were tested at two temperatures, 25 and 30 °C, and three dissolved oxygen concentrations, 0.6, 0.9, and 1.2 ppm. Survival analyses were performed on the data relating survival rate of each species to dissolved oxygen concentration, duration of exposure, fish size, and temperature. The data were analyzed using an LC50 approach for comparative purposes, and 12-h LC50 estimates ranged from 0.9 to 1.1 ppm O2. Spot and menhaden exposed to 1.2 ppm O2 showed no mortality in 24 h at 25 °C, and only 30-40% mortality at 30 °C. In contrast, both species experienced 100% mortality in 2-6 h at 0.6 ppm O2. There was an effect of size on hypoxia tolerance, with small spot being less tolerant than large spot, while the converse size effect was observed for menhaden. Spot were consistently less tolerant to hypoxia than menhaden and both species were less tolerant to hypoxia at 30 °C than at 25 °C. Preliminary experiments showed a 24-h acclimation to sublethal levels of hypoxia significantly reduced mortality upon subsequent exposure to lethal hypoxia concentrations.Our results indicate that direct mortality due to hypoxia will vary with species, size, and temperature, but will likely only be substantial when these species are exposed to oxygen concentrations less than about 1 ppm O2. Given the severity of hypoxia necessary to cause mortality and the ability of fish to behaviorally avoid hypoxia, direct mortality due to hypoxia may have limited impacts on fish population dynamics. Therefore, the greatest effects due to hypoxia may be caused by the stress imposed by sublethal hypoxic conditions alone or in concert with other stressors, or by indirect effects incurred by avoiding hypoxic areas. 相似文献
5.
J.E. Skjæraasen T. Nilsen N.A. Herbert V. Tronci A.G.V. Salvanes 《Journal of experimental marine biology and ecology》2008,358(1):70-77
Hypoxia can influence fish growth, survival and on larger scales, population structure. These effects may be influenced by water temperature, and may vary intra-specifically with genotype. In Atlantic cod (Gadus morhua L.), the two haemoglobin homozygotes (Hb-I?11 and Hb-I?22) vary in oxygen affinity at different temperatures, which is thought to correspond to variation in hypoxia tolerance. We therefore tested if hypoxic avoidance behaviour in cod 1) depends on ambient temperature and 2) is modified by haemoglobin genotype. In a laminar flow choice box, we subjected juvenile cod to an initial phase of non-escapable hypoxia, and a subsequent recovery phase, where one habitat was kept at 20% O2 saturation while the other was raised in steps to full saturation. The experiment was performed at 5 and 15 °C with Hb-I?11 and Hb-I?22 cod. Cod responded to inescapable hypoxia by reducing their overall swimming speed and then, at the initial levels of the recovery phase, avoiding the most hypoxic habitat, irrespective of temperature or genotype. Fish recovered quickly as O2 levels increased, as evidenced by increased swimming speed and time spent in the most hypoxic habitat. The avoidance response depended strongly on temperature: the relative reduction in speed and avoidance of the most hypoxic habitat was more pronounced at 15 than at 5 °C. During the recovery phase, stressed fish initially maintained a higher swimming speed in the most hypoxic habitat. However, as O2 increased, swimming speed in both habitats converged. This point of convergence occurred at a lower O2 saturation at 5 °C. Fish ventilation rate in inescapable hypoxia was also higher at 15 °C. Haemoglobin genotype did not influence either ventilation rates or the nature of the hypoxic avoidance response at either temperature, but Hb-I?11 cod swam faster than Hb-I?22 cod in normoxia at 15 °C. Our results indicate that increased temperature limits the ability of cod of both haemoglobin genotypes to exploit hypoxic habitats. This may have negative future consequences for coastal cod stocks in light of increasing global temperatures and eutrophication in coastal waters. 相似文献
6.
S. F. Perry C. J. Montpetit A. E. Julio K. Moore 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(4-5):335-343
The effect of long-term (7 day) anaemia on catecholamine release was examined in rainbow trout (Oncorhynchus mykiss) in vivo during acute exposure to hypoxia and in situ using a perfused post-cardinal vein preparation. The first goal was
to distinguish among reductions in blood O2 partial pressure, O2 concentration and haemoglobin percentage saturation as potential stimuli for, or correlates of, catecholamine secretion during
hypoxia. The second goal was to elucidate the role of these factors in promoting enhanced chromaffin cell responsiveness in
trout subjected to chronic hypoxia (Montpetit and Perry 1998). Anaemic fish (haematocrit lowered from 28.4±2.4% to 11.9±1.6%)
displayed a marked reduction in haemoglobin-O2 binding affinity [P
50 (P
aO2 at 50% Hb-O2 saturation) was increased from 14.7 mm Hg to 24.3 mm Hg]. Upon exposure to hypoxia, the anaemic fish released catecholamines
into their circulation at higher values of arterial O2 partial pressure (∼52 mm Hg versus ∼18 mm Hg) and haemoglobin O2 saturation (<70% versus <55%) than did control fish. In addition, anaemic fish achieved significantly greater circulating
levels of total catecholamines (noradrenaline plus adrenaline) during acute hypoxia (294.8±67.3 versus 107.0±35.6 nmol l−1). These results do not support the view that catecholamine release is triggered by a reduction in haemoglobin O2 saturation or arterial PO2, per se. Nor are they consistent with the idea that catecholamine release occurs at a threshold value of arterial PO2 corresponding to a critical reduction in blood O2 concentration. The effects of the non-selective cholinergic receptor carbachol on catecholamine secretion from chromaffin
tissue were assessed using perfused posterior cardinal vein preparations derived from control or anaemic fish. For adrenaline
secretion, there was no statistically significant change in the ED50 (dose eliciting 50% response). For noradrenaline secretion however, preparations originating from anaemic fish displayed
an enhanced responsiveness to carbachol as indicated by a significant 4.5-fold reduction in the carbachol ED50 value from 2.53 × 10−6 mol kg−1 to 5.67 × 10−7 mol kg−1. These results demonstrate that anaemia-induced hypoxaemia, in the absence of any lowering of PO2, is able to modulate the responsiveness of chromaffin cells to cholinergic stimulation.
Accepted: 21 April 1999 相似文献
7.
Mark J. Wuenschel 《Journal of experimental marine biology and ecology》2005,321(2):145-154
Juvenile gray snapper (Lutjanus griseus) occupy a wide range of estuarine and nearshore habitats that differ in physico-chemical properties. To quantify the energetic cost of inhabiting these different habitats, routine metabolism of individual gray snapper was measured in the laboratory at 20 combinations of temperature (18, 23, 28, and 33 °C) and salinity (5, 15, 25, 35, and 45 psu). An open, flow-through respirometer was used, enabling trials to be run for long periods (∼16 h), while maintaining water quality (dissolved O2>70% saturation), and providing fish sufficient time to habituate to the chambers undisturbed. Video recordings of fish in the respirometer chambers were analyzed to quantify the spontaneous activity rate of individuals. Analysis of covariance, using fish weight and mean activity rate as covariates, indicated significant temperature and salinity effects on oxygen consumption. Oxygen consumption was significantly higher at high salinities, and the salinity effect was temperature dependent. A polynomial equation describing oxygen consumption as a function of temperature and salinity indicated the increase due to salinity from 5 to 45 psu at high temperatures (30-33 °C) was equivalent to a 3 °C increase in temperature. At intermediate temperatures (24-26 °C), the increase due to salinity from 5 to 45 psu was less dramatic, equivalent to a 2 °C increase in temperature. At the lowest temperatures (18 °C), salinity did not have a significant effect on oxygen consumption. The increased metabolic costs in high salinities (∼7% at the high temperature) represent a significant energy cost for juveniles, that would need to be balanced by lower predation risk or greater food availability to result in similar juvenile production compared to lower salinity environments. 相似文献
8.
David W Hicks Robert F McMahon 《Journal of experimental marine biology and ecology》2002,277(1):61-78
The respiratory responses to increasing temperature and progressive hypoxia were examined relative to temperature acclimation in the nonindigenous, brown mussel, Perna perna (Mytilidae) from the Gulf of Mexico. When oxygen uptake rate (V?O2) was recorded at near full air O2 saturation, rate-temperature curves for Texas specimens of P. perna were sigmoidal, V?O2 generally increasing with increasing temperature but becoming suppressed as temperatures approached 10 and 30 °C, corresponding closely to this species' incipient thermal limits. At each tested temperature, V?O2 did not differ among individuals acclimated to 15, 20, or 25 °C. Lack of thermal acclimation was also reflected in acclimatory Q10 values>1.0 (range=1.34-2.14) recorded across acclimation groups at test temperatures equivalent to acclimation temperature. Low acute respiratory Q10 values in all acclimation groups across 15-20 °C indicated a limited capacity for thermal regulation of V?O2 within this temperature range. The ability of P. perna to regulate O2 uptake with progressive hypoxia was temperature-dependent, increasing from poor O2 regulation at 10 °C to good regulation at 30 °C. The O2 regulatory ability of P. perna and other open-water mytilids in declining O2 concentrations does not greatly differ from that of estuarine heterodont bivalves, suggesting that it is not a major factor preventing open-water species, such as P. perna, from invading estuarine environments. However, P. perna's inability to regulate O2 uptake at temperatures>25 °C combined with its relatively low upper thermal limit of 30 °C will likely prevent it from establishing permanent estuarine populations on Gulf of Mexico shores. 相似文献
9.
J. W. Nichols L. J. Weber 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(2):205-209
Summary Myoglobins from rat, coho salmon (Oncorhynchus kisutch), buffalo sculpin (Enophrys bison) hearts, and yellowfin tuna (Thunnus albacares) red skeletal muscle were partially purified and their O2 binding affinities determined. Commercially prepared sperm whale myoglobin was employed as an internal standard. Tested at 20°C, myoglobins from salmon and sculpin bound O2 with lower affinity than myoglobins from the rat or sperm whale. Oxygen binding studies at 12°C and 37°C suggest that this difference is adaptive, permitting myoglobins from cold-adapted fish to function at physiologically relevant temperatures. Taken together, purification and O2 binding data obtained in this study reveal a previously unrecognized diversity of myoglobin structure and function. 相似文献
10.
Synopsis The relationship between respiration and swimming speed of larvae and juveniles (2–100 mg fresh mass) of Danube bleak, Chalcalburnus chalcoides (Cyprinidae), was measured at 15° and 20° C under hypoxic (50% air saturation), normoxic, and hyperoxic (140% air saturation) conditions. In a flow-tunnel equipped with a flow-through respirometer the animals swam at speeds of up to 8 lengths · s-1; speeds were sustained for at least two minutes. The mass specific standard, routine, and active respiration rates declined with increasing body mass at both temperatures. Metabolic intensity increased with temperature, but also the critical swimming speed (at which oxygen uptake reached its maximum) was higher at 20° than at 15° C by about 30%. Nevertheless, the oxygen debt incurred by the fish at the highest speeds was about 40%, and the net cost of swimming about 32%, lower at 20° than at 15°C. The standard metabolic rate was more strongly dependent on temperature (Q10 around 2.5) than the maximum active rate (Q10 below 2). Whereas standard and routine respiration rates were well regulated over the pO2-range investigated (8.5–25.8 kPa), the active rates showed a conformer-like pattern, resulting in factorial scopes for activity between 2 and 4. Under hypoxia, the critical swimming speed was lower than under normoxia by about 1.51 · s-1, but the net cost of swimming was also lower by about 30%. On the other hand, hyperoxia neither increased the swimming performance nor did it lead to a further increase of the metabolic cost of swimming. The hypoxia experiments suggest that in response to lowered tensions of ambient oxygen maintenance functions of metabolism not directly related to swimming may be temporarily reduced, leading to increased apparent swimming efficiency under these conditions. The responses of the larvae of Danube bleak to low temperature and low ambient oxygen are discussed in terms of the metabolic strategies by which energy-limited animals meet the challenge of environmental deterioration. 相似文献
11.
S. Reuveny Y. J. Kim C. W. Kemp J. Shiloach 《Applied microbiology and biotechnology》1993,38(5):619-623
The effect of temperature and O2 saturation on the production of recombinant proteins -galactosidase and human glucocerebrosidase by Spodoptera frugiperda cells (Sf9) infected with recombinant Autographa californica nuclear polyhedrosis virus was investigated. The rates of cell growth, glucose consumption, O2 consumption and product expression were measured at temperatures between 22° C and 35° C. The results indicated that possible O2 limitation may be alleviated without compromising the maximum cell yield by lowering the incubation temperature from 27° C to 25° C. The expression level of the recombinant proteins at 27° C was similar to that obtained at 22° C and 25° C; lower protein yields were obtained at 30° C. An increase in temperature from 22° C to 27° C led to earlier production of the proteins and to an increase in the proportion of the product released outside the cells.
Correspondence to: J. Shiloach 相似文献
12.
Kjell Johansen Gunnar Lykkeboe Sonja Kornerup G. M. O. Maloiy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1980,136(1):71-76
Summary Respiratory gas exchange and blood respiratory properties have been studied in the East-African tree frogChiromantis petersi. This frog is unusually xerophilous, occupies dry habitats and prefers body temperatures near 40°C and direct solar exposure. Total O2 uptake was low at 81 l O2·g–1·h–1±19.0 (SD) at 25°C increasing to 253.5 l O2·g–1·h–1±94.8 (SD) at 40°C giving aQ
10 value of 2.1. Skin O2 uptake at 25°C was 38.5% of total. The gas exchange ratio was 0.71 for whole body gas exchange, 0.61 for the lungs and 1.02 for the skin at 25°C.Blood O2 affinity was low with aP
50 of 47.5 mmHg at 25°C and pH 7.65. Then
H-value at 25°C increased from 2.7 aroundP
50 to 5.0 at O2 saturations exceeding 70–80%. Surprisingly, blood O2 affinity was nearly insensitive to temperature expressed by a H value of ±1.0 kcal·mole between 25 and 40°C.The adaptive significance of the low O2 affinity, the increase ofn
H with O2 saturation and the temperature insensitive O2-Hb binding is discussed in relation to the high and fluctuating body temperatures ofChiromantis. 相似文献
13.
Stephen J. Walsh Dennis C. Haney Cindy M. Timmerman Robert M. Dorazio 《Environmental Biology of Fishes》1998,51(4):429-444
The robust redhorse, Moxostoma robustum (Teleostei: Catostomidae), is an imperiled sucker native to large rivers of the Atlantic slope of the southeastern United States. Juvenile M. robustum were tested for tolerances to temperature, salinity, pH, and hypoxia in order to evaluate basic early life-history requirements. Static (acute) tests resulted in estimates of mean lower temperature tolerances (5.3–19.4 °C) that varied with prior thermal acclimation and indicated no apparent difference in tolerance among fish 30, 60, and 90 days old. Fish acclimated to 20 °C and 30 °C had significantly different mean critical thermal maxima (34.9 °C and 37.2 °C, respectively) and exhibited pronounced increased opercular ventilation rates with elevated temperatures. Fish exposed to acute and chronic increases in salinity showed unusual patterns of mortality above the isosmotic point (9 ppt) that reflected possible differences in body mass and prior acclimation conditions (i.e., water ionic composition); small fish and those held in soft water were the least tolerant of increased salinity. Abrupt exposure to extreme pH values resulted in greater than 50% mortality at pH values below 4.3 and above 9.5 within a 96-hour period. Fish exposed to progressive hypoxia utilized aquatic surface respiration at a mean oxygen concentration of 0.72–0.80 mg O2 l-1 (20 °C and 30 °C acclimated fish, respectively), and lost equilibrium at 0.54–0.57 mg O2 l-1. Juvenile M. robustum are moderately tolerant of a wide range of ambient physicochemical parameters, but further research is needed to determine how both abiotic and biotic factors have contributed to population decline and extirpation of this species. 相似文献
14.
Routine oxygen consumption rates (MO2) and swimming activity rates of juvenile white sturgeon were determined using closed respirometers at life-interval-appropriate temperatures: 10° C (0.2 g mean wet weight), 16° C (1.9 g mean wet weight), and 20° C (63.1 g mean wet weight) under normoxic (PO2 > 140 mmHg) and moderately hypoxic (PO2=80 ± 5.0 mmHg) water conditions. At all temperatures and body sizes, hypoxia significantly depressed (p < 0.05) MO2 (57% mean reduction) and swimming activity (70% mean reduction). Overall mean MO2 was 228 µg O2 g-1 wet weight h-1 (normoxia) and 99 µg O2 g-1 wet weight h-1 (hypoxia). Thus, juvenile white sturgeon appear to decrease overall energy expenditures (hypometabolism) during hypoxia via reductions in spontaneous swimming activity. This is a life style that may increase survival during widespread or prolonged environmental hypoxia. 相似文献
15.
Lowe CJ Seebacher F Davison W 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2005,175(2):97-105
The Antarctic notothenioids are among the most stenothermal of fishes, well adapted to their stable, cold and icy environment. The current study set out to investigate the thermal sensitivity/insensitivity of heart rate and ventral aortic blood pressure of the Antarctic nototheniid fish Pagothenia borchgrevinki over a range of temperatures. The heart rate increased rapidly from –1 to 6°C (Q10=2.0–3.3), but was relatively insensitive to temperature above the ~6°C lethal limit of the species (Q10=1.2). The increase in heart rate from –1 to 6°C was the result of a 45% increase in excitatory adrenergic tone, masking a 37% increase in inhibitory cholinergic tone. Ventral aortic pressure was regulated well above the lethal limit, up to at least 10°C. With the return of the fish to environmental temperatures, the heart rate rapidly decreased back to control levels, while ventral aortic pressure increased and remained elevated for over an hour following a 6°C exposure. 相似文献
16.
Mogens L. Glass Atsushi Ishimatsu Kjell Johansen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(3):425-430
Summary The snake-head fish (Channa argus) is an obligate air-breather inhabiting fresh waters in the temperate zone of East Asia.Ventilation of the air-breathing organ and aerial gas exchange were measured in 1 to 2 kg specimens at 15 and 25°C. Additionally, the ventilatory responses to hypoxia and hypercapnia were studied. Aerial ventilation increased from 1.1 to 2.9 mlbtps·kg–1·min–1 when temperature rose from 15 to 25°C. Concomitantly, O2-uptake through airbreathing increased from 0.1 mlstpd·kg–1·min–1 (15°C) to 0.28 mlstpd·kg–1·min–1 (25°C), whereas aerial gas exchange was less important for CO2-climination as evident from low gas exchange ratios (0.16 at 15°C, 0.29 at 25°C).Ventilation increases only slightly in response to inspiration of hypercapnic gas mixtures or to hypoxic conditions in water. By contrast, inspiration of hypoxic gas mixtures caused marked increases of ventilation in particular at the higher temperature.Aerial ventilation inChanna is low compared to values for ectothermic pulmonary breathers. However, its ventilatory responses to hypoxia strikingly resemble those of reptiles: The most marked ventilatory response to hypoxia occurs at the higher temperature where the demands for O2 are greatest. 相似文献
17.
Regan A. McNatt James A. Rice 《Journal of experimental marine biology and ecology》2004,311(1):147-156
As eutrophication of coastal waters increases, water quality issues such as hypoxia have come to the forefront of environmental concerns for many estuarine systems. Chronic hypoxia during the summer has become a common occurrence in numerous estuaries, degrading nursery habitat and increasing the potential for exposure of juvenile fish to low levels of dissolved oxygen (DO).We conducted a laboratory study to investigate how hypoxic conditions and temperature affect growth rates of two juvenile estuary-dependent fish: the Atlantic menhaden (Brevoortia tyrannus) and spot (Leiostomus xanthurus). For a 2-week period, we exposed the fish to one of four constant DO levels (6.0, 4.0, 2.0 or 1.5 mg O2 l−1), at one of two temperatures (25 or 30 °C). A fifth DO treatment, included for spot at 30 °C, allowed DO to fluctuate from 10.0 mg O2 l−1 during the day, to 2.0 mg O2 l−1 at night. This diel fluctuation approximated the natural DO cycle in tidal estuarine creeks. Size measurements were recorded at the beginning, middle and end of experiments.Growth rates were generally unaffected by low DO until concentrations dropped to 1.5 mg O2 l−1, resulting in 31-89% growth reductions. Our results suggest that DO levels must be severely depressed, and in fact, approaching lethal limits, to negatively impact growth of juvenile spot and Atlantic menhaden. 相似文献
18.
Oxygen consumption (VO2) of juvenile Arctic cod (Boreogadus saida) was investigated at low tempera tures (six temperatures; range -0.5 to 2.7°C). Small (mean wt. 6–8 g) and large (mean wt. 14 g) fish were acclimated, or adjusted to a constant temperature (0.4°C), for 5 months and then tested for metabolic cold adaptation (elevated metabolic rates in polar fishes). Short-term (2 weeks) acclimated fish showed elevated VO2 similar to previously established values for polar fishes, but there was no such evidence after longterm acclimation. Long-term acclimation caused VO2 values to drop significantly (from 86.0 to 46.5 mg O2·kg–1·h–1, at 0.4°C), which showed that metabolic cold adaptation was a phenomenon caused by insufficien: acclimation time for fish in respiration experiments. We also measured the effects of temperature and feeding on VO2. A temperature increase of 2.3°C resulted in relatively large increases in VO2 for both longand short-term acclimated fish (Q10 = 6.7 and 7.1, respectively), which suggests that metabolic processes are strongly influenced by temperature when it is close to zero. Feeding individuals to satiation caused significant increases in VO2 above pre-fed values (34–60% within 1–2 days after feeding). Respiration budgets of starved and fed Arctic cod at ambient temperatures in Resolute Bay N.W.T., Canada, were used to model annual respiration costs and potential weight loss. Low respiration costs for Arctic cod at ambient temperatures result in high growth efficiency during periods of feeding and low weight loss during periods of starvation. 相似文献
19.
Glauber S.F. da SilvaHumberto Giusti Luiz G.S. BrancoMogens L. Glass 《Journal of thermal biology》2011,36(8):521-526
The control of pulmonary ventilation in South American lungfish Lepidosiren paradoxa is poorly understood. Interactions between temperature and hypoxia are particularly relevant due to large seasonal variations of its habitat. Therefore, we tested the hypothesis that the ventilatory responses to aerial hypoxia of Lepidosiren are highly dependent on ambient temperature. We used a pneumotachograph to measure pulmonary ventilation (VE), tidal volume (VT) and respiratory frequency (fR) during normoxic (21% O2) and hypoxic (12%, 10% and 7% O2) conditions at two temperatures (25 and 35 °C). Blood gases, arterial PO2 (PaO2), arterial PCO2 (PaCO2) and arterial pH (pHa) were also evaluated. At 25 °C, VE increased significantly at 10% and 7% hypoxic levels when compared to the control value (21% O2). At 35 °C, all hypoxic levels elicited a significant increase of VE relative to control values. VE is augmented mostly by increases of respiratory frequency (fR), and there were significant interactions (p<0.001) between aerial hypoxia and temperature. PaCO2 increased from ∼22 mmHg (normoxic value at 25 °C) to ∼32 mmHg (normoxic value at 35 °C). Concomitantly, the pHa decreased from 7.51 (25 °C) to 7.38 (35 °C). Hypoxia-induced hyperventilation caused a reduction in PaCO2 and an increase in pHa, which were more pronounced at 35 °C than at 25 °C, reflecting an increased hyperventilation under the high temperature. In conclusion, the magnitude of ventilatory response is highly temperature-dependent in L. paradoxa, which is important for an animal experiencing large seasonal variations. 相似文献
20.
Development and fecundity of Scymnus levaillanti(Mulsant) were recorded at fiveconstant temperatures ranging from 15 to 35 ± 1 °C in 5 °C increments, 60 ± 5% RHand 16 h of artificial light (5000 Lux). Developmentaltime (egg to adult) of S. levaillantisignificantly decreased with increasing temperatures,ranging from 63.9 days at 15 °C to 11.1 days at35 °C. Development from egg to adult required305.2 DD above a developmental threshold estimated as11.7 °C. Oviposition periods lasted 86.5, 76.1,47.2, and 31.5 days at 20, 25, 30 and 35 °C,respectively. No eggs were deposited at 15 °C.Higher temperatures resulted in shorter generationtimes (TO) and in decreased net reproductiverates (RO) of the coccinellid. S.levaillanti kept at 30 °C produced 0.151females/female/day, the highest per capita rate ofpopulation growth (rm). The `functional response'of larvae and adults of S. levaillanti matcheswell that described by Holling (1959) as Type 2.Daily number of eggs deposited by females increased toa plateau with increasing prey density. Resultsobtained here provide information about the biology ofS. levaillanti, and its feeding capacityindicates that it may act as an important control agent. 相似文献