Daily Water Loss Research Articles

Über den H2O-Gaswechsel von Mercurialis perennis im submontanen Kalkbuchenwald.: I. Die Bedeutung steuernder Parameter für den Tagesgang der Transpiration in verschiedenen Phasen der Vegetationsentwicklung

During the vegetation period of 1982 the transpiration in Mercurialis perennis was investigated in a beech forest on limestone in the environs of Göttingen by using a climatized gas exchange chamber. The H 2 O gas exchange was described with the aid of 6 daily courses of the transpiration and the photosynthetic active radiation, the saturation deficit of the air, the air temperature, the leaf conductance, and the leaf water potential. All data were measured simultaneously. By emp oying a multiple regression analysis the significance of the controlling parameters for the transpiration was analysed. Both the saturation deficit of the air and the radiation preponderantly determined the daily water loss in Mercurialis , though during the various periods of the vegetational development to a different degree. With regard to the daily courses of the transpiration the course of the leaf conductance was barely of importance, because its influence was mostly explained by the radiation. The absolute value of water loss during the particular days, however, was strongly determined by the level of leaf conductance, The air temperature did not control the transpiration, because its influence was already taken into consideration by the saturation deficit of the air.

Ecophysiological studies on Welwitschia mirabilis in the Namib desert

To determine which CO 2 fixation pathway is used by the gymnosperm Welwitschia mirabilis Hoof. f. an extensive field study on diurnal CO 2 gas exchange, 14 CO 2 incorporation, chemical composition, distribution pattern and variation of organic acids, and transpiration was made in the Welwitschia Flats of the central Namib desert. The CO 2 gas exchange of W. mirabilis is that of a C 3 plant under arid conditions. No CO 2 uptake during the night was detected and the organic acids showed no day-night fluctuations that significantly exceeded the differences observed between the values obtained in a grid sampling over a whole leaf. The daily water loss of W. mirabilis by transpiration is considerable, reaching a peak value of 1,9 mmol m − 2 s − 1 around noon. Problems with respect to water supply to maintain such transpiration rates are discussed. In spite of the evidence for a C 3 -pathway the δ 13 C values are in the range of CAM plants. Reasons for such values in W. mirabilis are discussed.

Avian Reproduction over an Altitudinal Gradient. II. Physical Characteristics and Water Loss of Eggs

Although the effective diffusion coefficient for gases is inversely related to barometric pressure, rates of daily water loss during natural incubation and final water contents of pipped embryos are independent of altitude in eggs of redwinged blackbirds (Agelaius phoeniceus) breeding from sea level to 3,050 m. These results indicate that the increase in diffusion of water vapor from the egg has been offset in some manner in populations of this species breeding at high altitudes. Eggs of redwinged blackbirds and robins (Turdus migratorius) breeding from sea level to 3,050 and 3,450 m, respectively, were analyzed for eggshell conductance, egg mass, water content, shell thickness, and incubation temperature. Of these, eggshell conductance showed the only meaningful relation to barometric pressure and may serve to control rates of gaseous diffusion at high altitudes.

Water and sodium balance: the effect of the air-fluidized bed on burned patients

Five patients with burned areas from 20 to 40 per cent BSA were studied in the air-fluidized bed during the first 2-week period post burn. Patients with abnormal renal and intestinal functions and with previous pathological history were not incorporated in the study. The patients were treated by the exposure method, and no surgical procedure was carried out during the study. The water and sodium balances were calculated from intravenous and oral intakes, urine-outflow, urinary sodium excretion and weight changes. In addition measurements of the sodium space were performed in two patients, using Sodium 24. Evaporative water loss was calculated during the first week, the sodium loss during the first and second weeks. As a result of the study the average daily evaporative water loss could be defined as: 0.81 ml/cm 2 burned area ±0.07 ml. We compared the actual evaporative water loss with two classical formulas: • - Davies, Lamke, Liljedahl (1974) (D.L.L.) min: 0.3 ml × cm 2 burned area = ml/day=D.L.L. (0.3) Max: 0.45 ml × cm 2 burned area = ml/day = D.L.L. (0.45) • - Scott, McDougall, Slade, Pruitt (1978) (S.M.S.P.) (25 + %)x BSA = ml/h = S.M.S.P. • - Scott, McDougall, Slade, Pruitt (1978) (S.M.S.P.) (25 + %)x BSA = ml/h = S.M.S.P. The average calculated daily evaporative water was: D.L.L. (0.3)+ 5 litre/m 2 burned area D.L.L. (0.45)+3.5 1/m 2 burned area S.M.S.P.+4 litre/m 2 burned area. This ‘extra’ evaporative water loss was closely related to the body burned surface. Correlation coefficient: D.L.L. (0.3)=0.99 D.L.L. (0.45)=0.98 S.M.S.P. =0.97. Day 2 and day 3 showed the most important water loss per cm 2 burned area. On the other hand, the sodium loss was found to be as expected: daily average: 0.02 mmol/cm 2 burned area.

Ecophysiology of two solar tracking desert winter annuals : IV. Effects of leaf orientation on calculated daily carbon gain and water use efficiency.

This paper represents an empirical study on the effect of different leaf orientations on the daily carbon gain and transpirational water loss of desert winter annuals. Laboratory physiological data on Malvastrum rotundifolium (Gray) and Lupinus arizonicus (Wats) were combined with energy budget concepts and field measurements of water relations and leaf movements to predict carbon gain patterns for horizontally oriented, diaheliotropic and paraheliotropic leaf movement types. The results showed contrasting patterns of carbon gain and water loss. L. arizonicus, which is capable of both dia- and paraheliotropic leaf movements, had the lowest rates of daily carbon gain and water loss. But these low rates resulted in the highest water use efficiencies under early season conditions and high water availability. M. rotundifolium, a diaheliotropic species, was predicted as having the highest rates of carbon gain and water loss on a daily basis over a wide range of environmental conditions and water availability. Despite possessing the highest rates for transpiration, its water use efficiency was higher in relation to other leaf movement types, under a variety of conditions. This result was extremely sensitive to soil water availability. The results were discussed in relation to the ecological ramifications of leaf movements in arid land annuals.

Stomatal regulation and water economy in crassulacean acid metabolism plants: an optimization model

Abstract It has been found that the stomatal behaviour of C3 and C4 plants can be predicted from the assumption that they increase transpiration whenever the increase δW in daily water loss is offset by a gain of at least λδW in carbon assimilation, where the minimum acceptable marginal conversion efficiency λ is determined by long term ecological factors, and is essentially constant within the course of a day. This paradigm is here extended to plants with Crassulacean acid metabolism (CAM). During daytime assimilation the results are the same as for C3 and C4 metabolisms. However night-time assimilation can be inhibited by the accumulation of malate in the cell vacuoles. In this event our model predicts that in a constant environment the stomatal conductance remains proportional to the square root of the mesophyll conductance as the latter declines. This is intermediate between keeping a constant stomatal conductance and keeping a constant intercellular CO2 concentration (as tends to occur in the C3/C4 model when illumination varies), and results in an increasing intercellular CO2 concentration towards the end of the night. This prediction accords with the Agave data of Nobel & Hartsock 1979. The model also predicts the allocation of time between C3 and CAM for different degrees of water stress. The results agree qualitatively with observation, even though physiological changes (other than stomatal conductance) are not included in the model.

Pre-pipping water loss from the eggs of the wedge-tailed shearwater

1. 1. The water loss from naturally incubated eggs of the Wedge-tailed Shearwater was measured, together with the water-vapor pressure of the incubated egg's micro-climate, the egg temperature, the water-vapor conductance of the shell and other characteristics of the shell. 2. 2. The mean daily water loss (. M H 2 O ) from the eggs (154.6 mg/day) was only 49.8% of the value expected on the basis of the mass of the freshly-laid egg. The low value for M H 2 o was attributed largely to a low water-vapor conductance ( G H 2 O ) of the shell (56.9% of predictions). The low G H 2 O . in turn, was due to fewer pores in the shell. 3. 3. Egg temperature (35.0 C) was lower than that of the eggs of birds in general, and this was considered to be a contributory factor to the low daily water loss. 4. 4. The water-vapor pressure ( P H 2O nest) of the egg's microclimate (19.57 torr) was similar to that of many surface-nesting birds in spite of the burrow-nesting habits of the shearwaters. 5. 5. It was calculated that the total pre-pippiny water loss from the eggs represented 12.2% of the initial mass of egg. 6. 6. It was concluded that prolonged incubation in the Wedge-tailed Shearwater, as in other smaller Procellariiformes. is associated with reduced values for . M H 2O and G H 2O and fewer pores in the shell.

Respiratory Gas Exchange and Growth of White Tern Embryos

-The parameters of respiratory gas exchange and growth in White Tern (Gygis alba) eggs were examined during natural incubation. The 02 consumption of eggs (Mo2) reached a plateau on day 32 of the 35.5-day incubation period resulting in an average Mo2 of 159 ml 02 STPD' day-' immediately prior to external pipping, and air cell gas tensions of 100 torr for 02 and 49 torr for CO2. Mo2 increased rapidly during the 5.2-day pip (star fracture)-to-hatch interval, achieving an 02 uptake of 470 ml 02 STPD day-1 in hatchling chicks. The level of pre-pipping Io02 appears to be adaptive to prolonged incubation and is related to the extent to which the incubation period deviates from the expected value based on initial egg mass. The mean pre-external pipping daily water loss (1MH20) was 78.7 mg day-' but increased to 275 mg day-' in externally pipped eggs, yielding a 17.5% total fractional mass loss over the entire incubation period. The pre-pipping cost of prolonged semi-precocial development, calculated by indirect calorimetry, was 2.71 kJ per gram yolk-free embryonic tissue. The total energy expenditure for embryonic development was 3.32 kJ per gram of hatchling tissue. The White Tern (Gygis alba) is one of only two terns with prolonged incubation (Whittow 1980). It has the longest incubation time in relation to its egg mass of any tern (Rahn et al. 1976, Whittow 1980). Available data on the incubation physiology of the White Tern suggest that it is subject to the same constraints as are other seabirds with prolonged incubation (Rahn et al. 1976, Whittow 1980). In addition, the eggs are adapted for prolonged incubation through curtailment of daily water loss from the egg; this is related to the relatively low watervapor conductance of the shell and a low egg temperature (Rahn et al. 1976, Howell 1978). In procellariiform seabirds, prolonged incubation is associated also with slow embryonic growth and an increased energy cost of incubation (Ackerman et al. 1980, Whittow 1980, Pettit et al. 1981a, b). However, the degree of development at hatching is greater in the White Tern (semiprecocial) than in the Procellariiformes, which are considered to be semi-altricial (Nice 1962). The White Tern and procellariiforms may therefore differ in the oxygen and energy cost of incubation. The present study was undertaken in order to provide information on the growth, embryonic oxygen consumption, and the energetics of incubation in the White Tern. An important part of our study was to document the even s occurring between pipping and hatching, signalling the transition from diffusi e gas transport across the pores of the shell to e convective gas transport of the lungs.

Biobehavioral determinants of evaporative water loss in the rat

R. C. Ritter and A. N. Epstein (1974, Behavioral Biology , 11 , 581–585) reported that grooming water loss constituted 30% of the total evaporative water loss of the rat during a 24-hr test in the absence of food and water. They suggested that dehydrated rats may conserve water behaviorally by grooming less, predicting that grooming water loss should increase with ingestants available. The two experiments reported here tested the hypothesis and extended our overall understanding of the behavioral and physiological determinants of evaporative water loss. In the first experiment the total evaporative water loss of Sprague—Dawley rats ( Rattus norvegicus ) was measured over 23 hr using the technique of F. R. Hainsworth (1967 , American Journal of Physiology , 212, 1288–1292). The magnitude of grooming water loss was determined by subtracting the evaporative water loss of surgically desalivate rats (equivalent to insensible water loss) from that of intact controls. During testing, rats had either food and water, only water, or neither food nor water available. The second experiment shared the design of the first and quantified grooming and general activity (the main behavioral determinants of grooming and insensible water losses, respectively) using the apparatus of Beagley and Gallistel (1971 , Physiology and Behavior , 7, 273–276). Grooming water loss was found to constitute 7–8% of total daily evaporative water loss. Although dehydration reduced grooming behavior slightly, grooming water loss was not detectably altered; suggesting that rats do not groom less in order to conserve water when in a state of water need. Deprivation of food or of both food and water reduced insensible water loss by 35–40%. Since general activity was unaffected by the availability of ingestants, this latter effect appears to be physiologically, rather than behaviorally, mediated.

Water loss from a shortgrass steppe

Daily and hourly water loss from a shortgrass steppe in northeastern Colorado was determined for four years (1972–1975) with a weighing lysimeter. Daily potential evapotranspiration rates were also calculated, and canopy resistance was evaluated on an hourly basis for selected days. The results show that on a monthly basis water loss was generally equal to the water input, while actual water loss was substantially lower than the potential evapotranspiration rate. The daily water loss data show that water loss is approximately equal to the potential evapotranspiration rate immediately after large precipitation events, then decreases very rapidly for four days after the event. The precipitation data show that large events (> 15 mm day −1) contribute most of the annual total precipitation, with most of the annual water loss from the system occurring during the period (2–14 days) immediately following the large precipitation events. The hourly water loss data show that when the soil was wet, water loss was maintained at the maximum rate; however, as the soil dried out, the water loss rate fell below the potential rate during the middle of the day, with the rate falling below the potential rate at early morning hours with drier soils. The canopy resistance is fairly low (2–5 s cm −1) when the soil is wet and does not change throughout the daytime; however, as the soil dries, the resistance increases throughout the day with the greatest increase observed on the driest soils.

Water balance of cut and intact «Sonia» rose plants

Summary For validly interpreting certain aspects of cut-flower physiology it is a prerequisite to compare the behaviour of cut flowers with that of intact ones, side by side, under the same environmental conditions. Fresh weight, water loss and water uptake of hydroponically grown, single-stem roses with or without a root system were followed throughout one blooming period, by twice-daily weighings. In the intact plants shoot plus flower weight could be estimated reliably with a water-displacement technique eliminating root weight. Cut roses standing in water very soon started to develop a characteristic pattern of weight fluctuations, in accordance with the light-dark alternation, losing ca. 10% weight in the light and regaining it in darkness. The pattern persisted after petal shedding, but on a roughly 50% reduced scale; this means that both petals and foliage contributed to the fluctuations observed. In the intact roses actual weight losses only occurred shortly before petal shedding, in the light, and did not persist thereafter; thus here it was only the senescing petals that lost some of their water-retaining capacity. Total daily water loss and uptake of the cut roses were identical to those of the intact ones in the first 24 h, but rapidly declined subsequently, levelling off to some 10%. In the same lapse of time overall water loss and uptake of the intact roses slowly declined as well, by some 30%. In the dark periods water uptake of the cut roses did not decline, as it did in the light, but remained constant and equal to that of the intact roses for most of the time. This is taken to mean that the phenomenon of rapidly declining overall water uptake of cut roses is not caused by a massive, solid plugging of the xylem vessels, as almost generally inferred in the literature. An alternative hypothesis is put forward.

Increase in conductance to water vapor during incubation in eggs of two avian species

AbstractIn contrast to previously published observations of constant daily water loss during incubation in some large, precocial eggs, daily rates of water loss increase approximately 42% between days 1–4 in redwinged blackbird eggs and conductance to water vapor increases 47 and 48% during the early stages of incubation in red‐winged blackbird and robin eggs, respectively. Therefore, the age of eggs is one factor which must be considered when conductance of eggs of conspecific populations is compared between habitats or over altitudinal gradients.

Daily activity, thermoregulation and water loss in the tiger beetle Cicindela hybrida.

1. The tiger beetle Cicindela hybrida is a diurnal predator inhabiting open sandy areas. The activity pattern on a sunny day in May with a mean maximum surface temperature of 40°C is described (Fig. 2). The inactive period is spent in burrows in the sand and it is suggested that a threshold of 19°C releases the daily round of activity (Fig. 5). The animals appear on the sand between 7.00 and 10.00 and the number reaches a maximum at 34-42°C (surface temp.). The duration of the activity period is indirectly determined by the number of available prey which is maximal at 36°C and decreases both at higher and lower temperatures. Mean onset and termination of activity occur at about 28°C (surface temp.) when the expected capture rate is 3 per hour. In actograph experiments, onset was controlled by the illumination and occurred several hours before "dawn" (Fig. 9). 2. The preferred body temperature is at about 35°C and thermoregulatory behaviour patterns are used in order to approach this. At low ambient temperatures, body temperature is increased by sun-basking, while at high temperatures stilting is used to prevent it from increasing above 35°C. If the temperature becomes intolerably high, the animals dig into the sand (Figs. 8, 16). Measurements of body temperatures in the field show that tiger beetles have partial regulation (Fig. 10) and it is suggested that this is because the cost of thermoregulation is low, but prey is not abundant enough to allow a full exploitation of this, and predation (hunger) interferes with the thermoregulation. 3. An estimation of the daily water loss under field conditions is presented based on measurements of the water loss in the laboratory at different temperatures and relative humidities. These values are weighted by the times actually spent at different combinations in the field (Figs. 17, 19). The loss amounts to about 10% per day of initial body weight, and it is concluded that tiger beetles have not evolved any special adaptations with respect to this factor.

Studies of the environmental physiology of tropical merinos

Rectal temperature measurements of tropical Merino sheep taken in the sun during summer indicated that there were high and low temperature groups. Animals of low temperature status (e.g. 39.4°C) also exhibited a low respiration rate (e.g. 110/min) in comparison with their less adapted counterparts (40.0° and 190/min). These differences were greatest when ambient temperatures were high. The repeatability of temperature status was 0.46 (P < 0.01). Animals of folds (+) phenotype had significantly higher rectal temperatures than folds (–) animals (P < 0.05). Shearing caused a marked but transient increase in rectal temperature. Compensatory mechanisms apparently involved an increase in cutaneous heat dissipation and/or a decrease in exogenous heat load. Evaporative water loss (80–115 ml/kg/day) greatly exceeded the non-evaporative water loss (40–65 ml/kg/day) of sheep in metabolism cages. Respiratory water loss could account for only 8–10% of the total daily evaporative water loss. Non-respiratory evaporative water loss (as measured by difference) was c. 75–100 ml/kg/day. There were no striking differences between high and low temperature status sheep in this regard. Measurements of respiratory (2 ml/kg/hr) and non-respiratory (5.5 ml/kg/hr) evaporative water loss made in hygrometric tents suggested that the greater non-respiratory water loss was partly due to a higher rate of loss and partly to a longer period of loss per day. This suggestion was supported by the diurnal patterns of rectal temperatures and respiration rates reported here, though no firm conclusions could be made as to the thermotaxic effect of non-respiratory water loss and thermoregulation of tropical Merinos with varying amounts of wool cover.

Effect of strict bed rest for 30 days on human water metabolism

The effect of strict bed rest for 30 days on the state of the water metabolism, the kinetics of water excretion, and the mean daily water loss was studied in man. Hypokinesia was found to reduce the rate of water renewal and to decrease the total water loss of the body. The relative water content as a percentage of body weight on the 25th day of hypokinesia was identical with the control.

Transpiration and stomatal opening of x-irradiated broad bean seedlings

Transpiration, stomatal opening and osmotic pressure of epidermal and guard cells were measured in non-irradiated Vicia faba seedlings and at various times following exposure to 250 R of 230 KVp X-ray. Significant reduction in total daily water loss per plant was detected in irradiated plants which was largely associated with substantial inhibition of leaf proliferation and growth; however, water loss per unit leaf area was significantly reduced in irradiated plants at 14–16 days post irradiation. The reduced transpiration was associated with inhibition of stomatal opening from the 9th to 16th day after irradiation. The osmotic pressure of epidermal and guard cells was compared in control and irradiated plants ; the osmotic pressure of epidermal cells in irradiated plants appeared to be slightly higher than that of epidermal cells of non-irradiated plants. However, the slight osmotic pressure changes of epidermal cells in irradiated plants did not appear to be a major factor contributing to inhibition of stomatal opening in irradiated plants under the growth conditions of the experiments.

Evaporative water loss of adult surgical patients in Greece

Daily evaporative water loss was studied in seventy-two adult surgical patients in Greece. It was found to average 1,480 ml in preoperative patients and 1,751 ml in postoperative ones. It is concluded that the daily amount of water given to surgical patients for replacement of evaporative water loss in temperate climates should be 1,500 to 2,000 ml.

The role of air humidity and leaf temperature in controlling stomatal resistance of Prunus armeniaca L. under desert conditions : I. A simulation of the daily course of stomatal resistance.

Experiments with Prunus armeniaca were carried out under conditions of constant temperature but varying air humidity. Experiments were also contucted with a constant water vapor difference between the evaporating sites in a leaf and the air, but with varying leaf temperature. These served as a basis for predicting the daily course of total diffusion resistance under the natural climatic conditions of a desert. For the simulation, the rsults of the experiments at constant conditions with only one variable factor are fitted with empirical equations which serve as "calibration curves" to predict the change in diffusion resistance caused by a change in humidity and temperature calculated from the meteorological data of a desert day. The simulation shows that for P. armeniaca humidity and temperature are the dominating factors in controlling the daily course of diffusion resistance. For meteorologically very different days the simulation allows the increase in diffusion resistance in the morning to be predicted with an accuracy of 90%-105% as compared to directly observed measurements. In the afternoon, especially after extreme climatic conditions during the morning, the deviation between predicted and observed values of diffusion resistance may be greater, but not more than -20% to -30%. This possibly indicates the existence of an additional factor of significance which was not included in the simulation. The two peaked curves of net photosynthesis and transpiration characteristic of plants living under arid conditions can be explained in this species by the humidity-and temperature-controlled stomatal response. This stomatal regulation leads to a decreasing total daily transpirational water loss on a dry day as compared to a moist one. The significance of this controlling mechanism for the primary production and the water relations of P. armeniaca is discussed.

Anatomical and physiological studies of water balance in the millipedes Pachydesmus crassicutis (polydesmida) and Orthoporus texicolens (spirobolida)

1. 1. A spiracular closing mechanism is lacking in both Pachydesmus crassicutis and Orthoporus texicolens, but in the latter the spiracles can be closed by a combination of diplosegmental overlap and close appression of the coxae. 2. 2. Cuticular water loss accounts for about half the daily water loss in O. texicolens under desiccating conditions, but in P. crassicutis so much water is lost via the respiratory system that cuticular water loss (except for teneral forms) is minor in comparison. 3. 3. P. crassicutis has a greater desiccation tolerance (65 per cent weight loss at death) than O. texicolens (40 per cent weight loss at death), but O. texicolens has a greater tolerance to desiccating conditions (17 days until death) than P. crassicutis (1 day until death) at 24 mm S.D., 24°C. 4. 4. Both species are oxygen conformers, but P. crassicutis has a much higher rate of oxygen consumption (105 μl/g per hr, 24°C) than O. texicolens (65·5 μl/g per hr, 24°C). 5. 5. Both species are ammonotelic, but P. crassicutis feces contains 0·009% urea, and O. texicolens feces contains 0·007% uric acid.

Water and Electrolyte Metabolism in the Arenicolous Lizard Uma notata notata

reaching a maximum during midday. Body temperatures of buried lizards (x = 34.3 C) were lower than in active lizards, but also were higher at midday than in the morning or afternoon. Eccritic body temperatures were lower during fall and winter than during spring and summer. Air temperatures 1 cm above the sand during times when lizards were active were also lower during fall and winter. Larger U. notata hibernated, while smaller individuals remained active throughout the year. U. notata were water independent when maintained in laboratory thermal gradients on a diet of meal worms. They possess a functional nasal salt gland with an ability to concentrate (x = 465 mEq C1-/L) and eliminate (x rate = 0.081 mg C1- g-1 day-1) chloride comparable to other terrestrial lizards. Cloacal water loss was low (x = 2.3 mg g-1 day-1) due probably, in part, to excretion of most nitrogenous wastes as urates or uric acid. Urinary chloride concentration was very low, but liquid urine was seldom voided. This may be due to resorption of water and salts from the kidneys or cloaca and excretion of the salts by the nasal gland. The relatively low rate of evaporative water loss (x = 0.88 mg g-1 hr-1) in dry air at 39.0 C compares favorably to rates for other lizards from arid habitats. Twenty-four hour rates of evaporative water loss (determined by direct weighing) for buried lizards at temperatures and humidities comparable to those in nature were lower than the rates for exposed lizards. A water budget calculated for representatives of U. notata showed that they remain in water balance even under conditions slightly more extreme than they normally encounter. It was concluded that evaporative loss in Uma, when it is exposed, is by far the most crucial factor in its water budget. Forty per cent of the total daily water loss occurs within the averaged 4.7 hr that the lizards are exposed. Uma saves considerable quantities of water by burying in the sand. Thus, these animals can exercise considerable behavioral control over their water budget by varying the length of time they are above or below the surface.