Studies on the water economy of some Australian frogs.

1965 ◽  
Vol 13 (2) ◽  
pp. 317 ◽  
Author(s):  
MR Warburg
Keyword(s):  
High Temperatures ◽  
Water Uptake ◽  
Water Loss ◽  
Vapour Pressure ◽  
Arid Regions ◽  
Vapour Pressure Deficit ◽  
Evaporative Water ◽  
Dry Air ◽  
Reduced Water ◽  
Semi Arid

The rate of evaporative water loss of several species of frog found in Australia and their ability to survive at high temperatures were studied at various temperatures in both dry and in humid air, and at constant vapour pressure deficit. The species studied were: Bufonidae, Bufo marinus (L.); Leptodactylidae, Crinia signifera Girard, Pseudophryne bibroni Gunther, Limnodynastes tasmaniensis Gunther, L. dorsalis (Gray), L. ornatus (Gray), Neobatrachus pictus Peters, N. centralis (Parker); Hylidae, Hyla ewingi (Dumeril & Bibron) and H. rubella Gray. To a certain extent, the trend for increased adaptation to terrestrial conditions follows the trend for reduced water loss. The rate of water uptake after dehydration is greatest in the burrowing frogs inhabiting arid and semi-arid regions. Survival at high temperatures in dry air was found to be a good criterion for judging the degree of adaptation of these frogs to life in arid regions.

The Evaporation of Water from Helix Aspersa

1964 ◽  
Vol 41 (4) ◽  
pp. 759-769
Author(s):  
JOHN MACHIN
Keyword(s):  
Water Content ◽  
Water Loss ◽  
Vapour Pressure ◽  
Freezing Point ◽  
Muscular Activity ◽  
Helix Aspersa ◽  
Distilled Water ◽  
Atmospheric Conditions ◽  
Evaporative Water ◽  
Dry Air

1. Observations of intact specimens of Helix aspersa together with experiments with isolated skin preparations are described. 2. Under normal atmospheric conditions increases in haemocoelic pressure, probably due to general muscular activity, are sufficient to maintain the superficial mucous coating of the skin. 3. Under conditions of rapid water loss more intense muscular undulations serve to spread mucus which collects in the grooves to more exposed areas of the skin. 4. The water content, the rate of water loss in dry air, the equilibrium in saturated air and depression of freezing point of isolated mucus samples have been measured. 5. The vapour pressure of mucus has been shown to be within 0.4% of that of distilled water under the same conditions. 6. The significance of the above findings is discussed in relation to evaporative water loss and water uptake of an intact snail.

scholarly journals Can birds do it too? Evidence for convergence in evaporative water loss regulation for birds and mammals

2017 ◽  
Vol 284 (1867) ◽  
pp. 20171478 ◽  
Author(s):  
E. C. Eto ◽  
P. C. Withers ◽  
C. E. Cooper
Keyword(s):  
Water Vapour ◽  
Water Loss ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Ambient Air ◽  
Evaporative Water Loss ◽  
Water Vapour Pressure ◽  
Evaporative Heat Loss ◽  
Evaporative Water ◽  
Water Vapour Pressure Deficit

Birds have many physiological characteristics that are convergent with mammals. In the light of recent evidence that mammals can maintain a constant insensible evaporative water loss (EWL) over a range of perturbing environmental conditions, we hypothesized that birds might also regulate insensible EWL, reflecting this convergence. We found that budgerigars ( Melopsittacus undulatus ) maintain EWL constant over a range of relative humidities at three ambient temperatures. EWL, expressed as a function of water vapour pressure deficit, differed from a physical model where the water vapour pressure deficit between the animal and the ambient air is the driver of evaporation, indicating physiological control of EWL. Regulating EWL avoids thermoregulatory impacts of varied evaporative heat loss; changes in relative humidity had no effect on body temperature, metabolic rate or thermal conductance. Our findings that a small bird can regulate EWL are evidence that this is a common feature of convergently endothermic birds and mammals, and may therefore be a fundamental characteristic of endothermy.

Ecohydrology of CAM plants: environmental co-benefits for agroecosystems

2020 ◽  
Author(s):  
Amilcare Porporato ◽  
Samantha Hartzell
Keyword(s):  
Arid Regions ◽  
Carbon Assimilation ◽  
Biofuel Production ◽  
Productivity Index ◽  
Cam Plants ◽  
Marginal Lands ◽  
C3 Photosynthesis ◽  
Consistent Basis ◽  
Reduced Water ◽  
Semi Arid

<p>In spite of their potential as low input crops in arid and semi-arid regions, limitations in CAM (Crassulacean Acid Metabolism) modeling have made it difficult to compare the productivity and water use of CAM crops with their C3 and C4 counterparts on a consistent basis. Using the Photo3 model, which adds a malic acid storage and circadian rhythm to the widely accepted Farquhar et al. model for C3 photosynthesis, we analyze the coupling of CAM carbon assimilation and transpiration with the soil-plant-atmosphere continuum at an hourly timescale to explore the potential of prickly pear and agave in several semiarid locations. Model results are compared with experimental data and contrasted with results generated using the widely used and empirically based Environmental Productivity Index introduced by Park Nobel in 1980. Using model results for CAM as well as C3 and C4 species, we explore how agricultural productivity in these locations may be optimized by diversifying planting strategies among the three photosynthetic pathways. This work aims to assist in better understanding the potential of CAM for food and biofuel production in arid and semiarid regions of the world accounting also for environmental co-benefits related to enhanced carbon sequestration and reduced water demand in semi-arid, marginal lands.</p><p> </p>

Needle conductance and root egress of containerized Scots pine and Norway spruce seedlings after surface and deep planting

1987 ◽  
Vol 17 (8) ◽  
pp. 783-786 ◽  
Author(s):  
Karl-Anders Högberg
Keyword(s):  
Water Stress ◽  
Norway Spruce ◽  
Water Uptake ◽  
Scots Pine ◽  
Root Development ◽  
Water Loss ◽  
Early Stage ◽  
Evaporative Water ◽  
Soil Layers ◽  
Pine Seedlings

Surface planting and deep planting were compared with respect to water uptake and root development in the early stage of field establishment. The material consisted of containerized Scots pine (Pinussylvestris L.) and Norway spruce (Piceaabies (L.) Karst.) seedlings. For both species, surface planted seedlings showed less root egress 5 weeks after planting compared with deep planted. Needle conductance was lower for surface planted than deep planted pine seedlings. For pine seedlings high correlation was found between root egress and needle conductance 5 weeks after planting for surface planting but not for deep planting. It is concluded that surface planting increases the water stress risk during establishment. Evaporative water loss from the root ball and the upper soil layers is discussed as the main cause to this effect.

Germination characteristics of seven Stylosanthes species

1976 ◽  
Vol 16 (82) ◽  
pp. 723 ◽  
Author(s):  
JG McIvor
Keyword(s):  
Moisture Content ◽  
High Temperatures ◽  
Water Uptake ◽  
Water Loss ◽  
Initial Rate ◽  
Germination Rate ◽  
Moisture Stress ◽  
Germination Response ◽  
Germination Characteristics

The germination response of dehulled, scarified seeds to a range of constant and alternating temperatures, and to moisture stress was measured in seven Stylosanthes species. Rates of water uptake and loss were also measured. With constant temperatures, both total germination and germination rate were greatest at 25�C for all species except for S. hamata which germinated faster at 30�C. Both higher and lower temperatures slowed and depressed germination. Constant and alternating temperatures produced similar results except at high temperatures where germination was less with the alternating regime. Moisture stress greatly reduced germination of S. guyanensis cv. Cook, S. scabra and S. viscosa but had little effect on S. fruticosa, S. guyanensis CPI 40294 and S. subsericea. Initial rate of water uptake was greatest for S. hamata and S. subsericea but moisture content was similar for all species by 18 hours. There were no differences between species in rate of water loss from imbibed seeds.

Studies on the environmental physiology of some Australian lizards from arid and semi-arid habitats.

1965 ◽  
Vol 13 (4) ◽  
pp. 563 ◽  
Author(s):  
MR Warburg
Keyword(s):  
High Temperatures ◽  
Water Loss ◽  
Low Temperatures ◽  
The Body ◽  
The Other ◽  
Arid Conditions ◽  
Arid Habitat ◽  
Rate Of Evaporation ◽  
Semi Arid ◽  
Low Rate

The microclimate of an arid habitat was studied at midsummer. Several species of lizards found there, and in semi-arid habitats, were examined. The lizards were: Agamidae; Amphibolurus reticulatus inermis (De Vis), A pictus Peters, A. cristatus Gray, and A. decresii Dumeril & Bibron; Varanidae, Varanus gouldii Gray; Scincidae, Tiliqua melanops Stirling & Ziets. The rate of water loss by evaporation was determined under different combinations of temperature and humidity. Of the lizards studied, A. r. inermis was the only species fully adapted to life in arid conditions. No evidence for evaporative cooling of the body at high temperatures was obtained. It is suggested that this lizard survives in arid habitats mainly because it is able to tolerate long exposures to high temperatures and low humidities, not because it is capable of maintaining low temperatures. The rate at which water is lost by this lizard was remarkably low when compared with the other lizards. The curves of increasing water loss in dry air at 37.5�C (in agamids) may be indicative of their degree of adaptedness. Thus, A. r. inermis has the lowest rate of water loss, followed by A. pictus, A. cristatus, and A. decresii, respectively. The skink, T. melanops, and the goanna, V. gouldii, show a fairly low rate of evaporation at that temperature.

Ecology of Australian Chats (Epthianura Gould): Reproduction in Aridity.

1979 ◽  
Vol 27 (2) ◽  
pp. 213 ◽  
Author(s):  
CK Williams
Keyword(s):  
Arid Regions ◽  
Vapour Pressure Deficit ◽  
Physiological Adaptation ◽  
Water Requirements ◽  
Territorial Defence ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Hormonal Mechanism ◽  
Gloger’S Rule ◽  
Breeding Seasons

The four species of Australian chats differentially occupy arid regions and are considered to have problems of water balance during reproduction. They breed mainly during the winter semester, when ambient temperatures and vapour pressure deficit are lower and evaporative losses of body water are reduced. During a drought breeding is depressed; but chats breed opportunistically after abundant rainfall and exploit, by nomadism, the unpredictable rainfall in semiarid and arid Australia. The breeding season of the most mesic species, Epthianura albifrons, is reduced in the more xeric regions. In arid sympatric breeding areas the more xeric species have the more extended breeding seasons. Chats are territorial only during reproduction. The male protects the receptive female and the eggs and offspring, but not environmental resources. Territorial defence involves plumage pigmentation consistent with Gloger's rule, plumage patterns, postures and ritualized fighting displays. Territoriality and territorial behaviour are reduced in the more mesic species. This is consistent with relative rates of evaporative water loss, synchrony and apparent density of nesting, water requirements and physiological adaptation to aridity. A hypothesis is presented which suggests an adaptive hormonal mechanism relating to physiological adaptation to aridity and determining the different plumages.

scholarly journals Airway Surface Liquid Osmolality Measured Using Fluorophore-Encapsulated Liposomes

2001 ◽  
Vol 117 (5) ◽  
pp. 423-430 ◽  
Author(s):  
Sujatha Jayaraman ◽  
Yuanlin Song ◽  
A.S. Verkman
Keyword(s):  
Epithelial Cells ◽  
Water Loss ◽  
Airway Epithelial Cells ◽  
Evaporative Water Loss ◽  
Airway Surface Liquid ◽  
Airway Epithelial ◽  
Evaporative Water ◽  
Dry Air ◽  
Surface Liquid ◽  
Sulforhodamine 101

The airway surface liquid (ASL) is the thin layer of fluid coating the luminal surface of airway epithelial cells at an air interface. Its composition and osmolality are thought to be important in normal airway physiology and in airway diseases such as asthma and cystic fibrosis. The determinants of ASL osmolality include epithelial cell solute and water transport properties, evaporative water loss, and the composition of secreted fluids. We developed a noninvasive approach to measure ASL osmolality using osmotically sensitive 400-nm-diam liposomes composed of phosphatidylcholine/cholesterol/polyethylene glycol-phosphatidylcholine (1:0.3:0.08 molar ratio). Calcein was encapsulated in the liposomes at self-quenching concentrations (30 mM) as a volume-sensitive marker, together with sulforhodamine 101 (2 mM) as a volume-insensitive reference. Liposome calcein/sulforhodamine 101 fluorescence ratios responded rapidly (<0.2 s) and stably to changes in solution osmolality. ASL osmolality was determined from calcein/sulforhodamine 101 fluorescence ratios after addition of microliter quantities of liposome suspensions to the ASL. In bovine airway epithelial cells cultured on porous supports at an air–liquid interface, ASL thickness (by confocal microscopy) was 22 μm and osmolality was 325 ± 12 mOsm. In anesthetized mice in which a transparent window was created in the trachea, ASL thickness was 55 μm and osmolality was 330 ± 36 mOsm. ASL osmolality was not affected by pharmacological inhibition of CFTR in airway cell cultures or by genetic deletion of CFTR in knockout mice. ASL osmolality could be increased substantially to >400 mOsm by exposure of the epithelium to dry air; the data were modeled mathematically using measured rates of osmosis and evaporative water loss. These results establish a ratio imaging method to map osmolality in biological compartments. ASL fluid is approximately isosmolar under normal physiological conditions, but can become hyperosmolar when exposed to dry air, which may induce cough and airway reactivity in some patients.

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