scholarly journals Evaporative Water Losses of Some Small Australian Lizards

Ecology ◽  
1966 ◽  
Vol 47 (4) ◽  
pp. 589-594 ◽  
Author(s):  
William R. Dawson ◽  
Vaughan H. Shoemaker ◽  
Paul Licht
Keyword(s):  
Water Losses ◽  
Evaporative Water

scholarly journals The ship of the desert. The dromedary camel (Camelus dromedarius), a domesticated animal species well adapted to extreme conditions of aridness and heat

Rangifer ◽  
1990 ◽  
Vol 10 (3) ◽  
pp. 231 ◽  
Author(s):  
S. Bornstein
Keyword(s):  
Animal Species ◽  
Physiological Adaptation ◽  
Dromedary Camel ◽  
Large Animal ◽  
Water Losses ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Adaptive Mechanisms ◽  
Adaptation To Heat ◽  
Arabian Camel

The dromedary camel (Camel dromedarius) is extremely well adapted to life in hot and arid lands. In terms of physiological adaptation to heat and water deprivation it surpasses by far every other large animal of which data have been collected. None of the adaptive mechanisms to cope with the environmental stresses are unique to the Arabian camel, but the efficiency of its adaptation is superior. At high ambient temperatures the camels adapt to the scarcity of water by reducing their faecal, urinary and evaporative water losses. During dehydration, the kidneys reduce water losses both by decreasing the glomerual filtration rate and by increasing the tubular reabsorption of water. Also their ability of regulating their body temperature from 34.5-40.7 °C conserves a lot of water, when most needed.

scholarly journals Thermal dehydration-induced thirst in spontaneously hypertensive rats

1999 ◽  
Vol 276 (5) ◽  
pp. R1302-R1310 ◽  
Author(s):  
Christopher C. Barney ◽  
Gina L. Smith ◽  
Michael M. Folkerts
Keyword(s):  
Water Status ◽  
Heat Exposure ◽  
Plasma Osmolality ◽  
Thermal Response ◽  
Hemoglobin Concentration ◽  
Water Losses ◽  
Evaporative Water ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Wistar Kyoto

Spontaneously hypertensive (SH) rats and normotensive Wistar-Kyoto (WKY) rats were exposed to either 25 or 37.5°C for 3.5 h, and their thermal and water balance responses were compared. After exposure, either a blood sample was obtained or the rats were allowed to rehydrate for 4 h. SH rats had both higher core temperatures and evaporative water losses during heat exposure. Measurements of hematocrit, hemoglobin concentration, plasma protein and sodium concentrations, and plasma osmolality indirectly showed that the SH rats were dehydrated relative to the WKY rats after exposure to either 25 or 37.5°C. SH rats drank significantly more water but also had significantly higher urine volumes than the WKY rats and thus rehydrated only slightly better than the WKY rats. SH and WKY rats had similar levels of water intake and urine output after 24 h of water deprivation. The elevated thermal response of SH rats to heat exposure does not appear to lead to uncompensatable changes in body water status.

Gastrointestinal and renal responses to water intake in the green-backed firecrown (Sephanoides sephanoides), a South American hummingbird

2006 ◽  
Vol 291 (3) ◽  
pp. R830-R836 ◽  
Author(s):  
Bradley Hartman Bakken ◽  
Pablo Sabat
Keyword(s):  
Water Absorption ◽  
Water Intake ◽  
Water Flux ◽  
Intake Rate ◽  
South American ◽  
Water Reabsorption ◽  
Water Losses ◽  
Evaporative Water ◽  
Water Loading ◽  
Nectar Feeding

To maintain water balance, nectar-feeding vertebrates oscillate between meeting the challenges of avoiding overhydration and preventing dehydration. To understand how green-backed firecrowns ( Sephanoides sephanoides) accomplish this, we examined the response of water-handling processes in the gastrointestinal tract (GIT) and kidney to different rates of water intake during the evening, night, and morning. Fractional water absorption in the GIT was independent of water intake rate (evening: 0.91 ± 0.08; morning: 0.88 ± 0.04). Consistent with this nonregulated water absorption, we found linear increases in water flux, fractional turnover of body water, and the rate of renal water loading as water intake rate increased during both the evening and morning. Despite these relationships, glomerular filtration rate (GFR) was insensitive to water loading (evening: 2.08 ± 0.56 ml/h; morning: 1.84 ± 0.68 ml/h) and less than the allometric expectation (2.92 ml/h). During the evening, fractional renal water reabsorption decreased linearly as the rate of water intake increased. At night, a period of natural fasting for hummingbirds, mean GFR was not different from zero (0.00 ± 0.05 ml/h). These findings indicate that green-backed firecrowns eliminate excess ingested water by decreasing water reabsorption in the kidney; to conserve water, it appears that hummingbirds arrest whole kidney GFR, effectively preventing urinary water losses. After discounting evaporative water losses, our results show that hummingbirds rely principally on their renal system to resolve the osmoregulatory quandary posed by nectarivory.

scholarly journals Does ecophysiology mediate reptile responses to fire regimes? Evidence from Iberian lizards

2016 ◽  
Author(s):  
Catarina C Ferreira ◽  
Xavier Santos ◽  
Miguel A. Carretero
Keyword(s):  
Repeated Measures ◽  
Fire History ◽  
Fire Regimes ◽  
Biological Traits ◽  
Adult Males ◽  
Lizard Species ◽  
Water Losses ◽  
Evaporative Water ◽  
Interspecific Differences ◽  
Psammodromus Algirus

Background. Reptiles are sensitive to habitat disturbance induced by wildfires but species frequently show opposing responses. Functional causes of such variability have been scarcely explored. In the northernmost limit of the Mediterranean bioregion, lizard species of Mediterranean affinity (Psammodromus algirus and Podarcis guadarramae) increase in abundance in burnt areas whereas Atlantic species (Lacerta schreiberi and Podarcis bocagei) decrease. Timon lepidus, the largest Mediterranean lizard in the region, show mixed responses depending on the locality and fire history. We tested if such interspecific differences are of functional nature, namely, if lizard ecophysiological traits may determine their response to fire. Based on the variation in habitat structure between burnt and unburnt sites, we hypothesise that Mediterranean species increasing density in open habitats promoted by frequent fire regimes should be more thermophile and suffer lower water losses than Atlantic species. Methods. We submitted 6-10 adult males of the five species to standard experiments for assessing preferred body temperatures (Tp) and evaporative water loss rates (EWL), and examined the variation among species and along time by means of repeated-measures AN(C)OVAs. Results. Results only partially supported our initial expectations, since the medium-sized P. algirus clearly attained higher Tp and lower EWL. The two small wall lizards (P. bocagei and P. guadarramae) displayed low Tp and high EWL while the two large green lizards (T. lepidus and L. schreiberi) displayed intermediate values for both parameters. Discussion. The predicted differences according to the biogeographic affinities within each pair were not fully confirmed. We conclude that ecophysiology may help to understand functional reptile responses to fire but other biological traits are also to be considered.

The effect of increased rectal temperature on nitrogen metabolism in Brahman cross and Shorthorn × Hereford steers fed on a low nitrogen roughage

1970 ◽  
Vol 21 (5) ◽  
pp. 857 ◽  
Author(s):  
JE Vercoe ◽  
JE Frisch
Keyword(s):  
Urinary Excretion ◽  
Nitrogen Metabolism ◽  
Rectal Temperature ◽  
Water Losses ◽  
Fixed Amount ◽  
Evaporative Water ◽  
Urea Nitrogen ◽  
Dry Matter Digestibility ◽  
Collection Period ◽  
Low Nitrogen

A study was made of the effect of increasing the rectal temperature on nitrogen metabolism in Brahman cross and British cross steers offered a fixed amount of a low nitrogen roughage. Increasing the rectal temperature by c. 1.3�C in either breed slightly depressed intake, increased the dry matter digestibility by a small but statistically significant amount, and had no effect on the nitrogen digestibility. It did not significantly increase the urinary excretion of total nitrogen or urea nitrogen over the whole collection period, but over the last 5 days there were increases in the urinary total and urea nitrogen excreted per day which in most cases were significant. Increasing the rectal temperature significantly increased the urinary excretion of creatinine. The ambient temperature at which rectal temperatures were increased by 1.3�C was 35�C for the British cross steers and 43' for the Brahman cross steers. At the increased rectal temperature, the Brahman cross steers drank significantly more water than the British cross steers although faecal and urinary water losses were not significantly different. The calculated evaporative water loss was higher in the Brahman cross steers than in the British cross steers when both breeds were heated.

Effect of ambient temperature on development of prostaglandin E1 hyperthermia in the rhesus monkey

1978 ◽  
Vol 44 (5) ◽  
pp. 751-758 ◽  
Author(s):  
C. C. Barney ◽  
R. S. Elizondo
Keyword(s):  
Rhesus Monkey ◽  
Metabolic Rate ◽  
Rhesus Monkeys ◽  
Prostaglandin E1 ◽  
Co2 Production ◽  
Evaporative Heat Loss ◽  
Water Losses ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Skin Temperatures

Prostaglandin E1 (PGE1) hyperthermia (fever) was studied at ambient temperatures (Ta) of 18, 27, and 35 degrees C in four male unanesthetized rhesus monkeys (Macaca mulatta) implanted with four guide tubes and one reentrant tube within the preoptic anterior hypothalamus (PO/AH). Rectal, hypothalamic, and mean weighted skin temperatures, O2 consumption, CO2 production, and respiratory and total evaporative water losses were measured continuously before and during PGE1 fever at each Ta. The febrile reponse to PO/AH PGE1 injection was dose responsive and was less at a Ta of 35 degrees C than at the other Ta's. At a Ta of 18 degrees C, fever was brought about primarily by an increase in metabolic rate. At a Ta of 27 degrees C, fever was produced by an increase in metabolic rate and by skin vasoconstriction. At a Ta of 35 degrees C, fever was the result of an increase in metabolic rate and a decrease in sweating evaporative heat loss. At each Ta some generalized skin vasconstriction also occurred. During the plateau phase of the fever, the measured heat losses and gains returned to near control levels. The data indicate that the rhesus monkey shows specific thermoregulatory responses to PO/AH PGE1 injection and would be a good model for the study of thermoregulation during fever in higher primates.

Droplet Coalescence and Departure on a Vibrating Film During Humid Air Condensation

2017 ◽  
Author(s):  
Ryan A. Huber ◽  
Melanie M. Derby
Keyword(s):  
Power Plant ◽  
Moist Air ◽  
Droplet Coalescence ◽  
Water Losses ◽  
Evaporative Water ◽  
Humid Environment ◽  
Air Stream ◽  
Power Plant Cooling ◽  
Condensed Liquid ◽  
Forced Movement

This paper investigates an approach to collect evaporated water from a moist air stream, a scenario found in many power plant cooling towers which utilize evaporation to cool, thereby resulting in evaporative water losses. For example, a 500 MW power plant may lose about 27m3/h (7133 gal/h) of water to evaporation during operation. When a cooled surface is placed in a warm humid environment, water condenses on the surface. The condensed liquid forms a thermal resistance, thereby reducing the condensation rate and water collected. The concept presented in this paper is to vibrate the cooled surface, thereby rapidly removing more droplets than gravity alone. With forced movement and through droplet coalescence, new droplets can nucleate in the space created by departing water droplets. Droplet nucleation, coalescence, and departure were investigated on vibrating and stationary Teflon films (contact angle 105°) in an environmental chamber at 30°C and 50% RH. Film vibrations of approximately 100 Hz were investigated. Droplet departure diameters were approximately 2–3 mm diameter on the vibrating surface and 6 mm on the stationary surface.

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