Seasonal Changes In Ambient Temperature Research Articles

Variation of δ18O and δD in precipitation and stream waters across the Kashmir Himalaya (India) to distinguish and estimate the seasonal sources of stream flow

Summary The spatial and temporal distribution of δ 18 O and δD measurements of precipitation and stream waters were used to distinguish various sources and components of stream flow and to estimate their residence times in snow dominated mountainous catchments of Kashmir Himalaya. A marked spatial and seasonal variability of stable isotopes of oxygen and hydrogen was observed in precipitation with δ 18 O and δD varied from −12.98‰ to −0.58‰ and −74.5‰ to −11.1‰, respectively during the period from November 2007 to January 2009. The seasonal changes in stable isotopes of precipitation with depleted and enriched 18 O and 2 H in January/March/May and July/September/November, respectively at each site are attributed to the seasonal changes in ambient temperature, precipitation, source of moisture and airmass trajectory. The mean altitude effect of −0.23‰ and −1.2‰ per 100 m change in elevation for δ 18 O and δD, respectively, was observed based on amount weighted mean precipitation isotopic composition data. Unlike precipitation, less variability of stable isotopes of streams was found with δ 18 O and δD ranging from −11.56‰ to −6.26‰ and −65.4‰ to −36.4‰, respectively, the depleted values being observed in the headwaters of the streams/tributaries and enriched values at lower elevations of the watersheds. The LMWL established for the Kashmir Himalayas, based on amount weighted monthly samples is δD = 7.59 (± 0.32) × δ 18 O + 11.79 (± 2.07) ( r 2 = 0.96) with lower slope and intercept than GMWL, is very close to the LMWL for the western Himalayas. The seasonal regression lines suggest the effect of evaporation with lower slopes and intercepts except in winter. The results suggest that the winter precipitation (snow) dominantly contributes the annual stream flow with average snowmelt contribution of about 29% in early spring, 66% in late spring, 61% in summer while the baseflow contribution is found in the order of 40% in autumn season. The mean stream residence times (MRTs) varied from 6 to 12.4 months. The longer MRT of the Liddar catchment is attributed to its complex topography and larger area.

Comparison of the Performance of 1966- Versus 2003-Type Turkeys When Fed Representative 1966 and 2003 Turkey Diets: Growth Rate, Livability, and Feed Conversion

Body weight, livability, and feed conversion of a randombred control turkey line (RBC2) started in 1966 at The Ohio State University was compared with that of modern commercial turkeys hatched in 2003 when fed representative 1966- and 2003-type diets from hatch (March 5, 2003) through 196 d of age. Each pen of modern turkeys consisted of 5 birds each of the Nicholas, British United Turkeys of America, and Hybrid strains. Eight groups (i.e., 2 strains (RBC2 vs. modern), 2 sexes, and 2 dietary regimens) were randomly assigned into each of 4 blocks of 8 litter floor pens (32 total) for growout. Using the BW performance of the 2 strains on the modern feed as the basis, the study showed that the 2003 turkeys were approximately twice as heavy as the 1966 RBC2 at the 4 slaughter ages and that tom weights have increased by 186, 208, 227, and 241 g/yr, and hen weights have increased by 164, 179, 186, and 205 g/yr at 112, 140, 168, and 196 d of age, respectively, over the past 37 yr. Cumulative feed conversion (kg of feed/kg of BW) was approximately 20% better in the 2003 tom turkey on the 2003 feed (2.638) than in the RBC2 tom on the 1966 feed (3.278) at 20 wk of age. Feed efficiency to 11 kg of BW in the 2003 toms (2.132 at 98 d of age) was approximately 50% better than in the RBC2 toms (4.208 at 196 d of age). The number of days to reach that weight was halved during this period of time. Growth performance during the different periods of the study appeared to be strongly affected by type of feed used and seasonal changes in ambient temperature. Overall livability was very good for all groups, but the mortality level of the RBC2 was consistently higher, although not significantly so, than for the modern birds.

Meteorology and the physical activity of the elderly: the Nakanojo Study

Seasonal changes in ambient temperature and day length are thought to modify habitual physical activity. However, relationships between such environmental factors and the daily physical activity of older populations remain unclear. The present study thus examined associations between meteorological variables and the number of steps taken per day by elderly Japanese. Continuous pedometer counts over a 450-day period were collected from 41 healthy subjects (age 71+/-4 years), none of whom engaged in any specific occupational activity or exercise programs. An electronic physical activity monitor was attached to a belt worn on the left side of the body throughout the day. Daily values for mean ambient temperature, duration of bright sunshine, mean wind speed, mean relative humidity, and precipitation were obtained from local meteorological stations. The day length was calculated from times of sunrise and sunset. Based on the entire group of 41 subjects (ensemble average), a subject's step count per day decreased exponentially with increasing precipitation (r2=0.19, P<0.05). On days when precipitation was <1 mm, the step count increased with the mean ambient temperature over the range of -2 to 17 degrees C, but decreased over the range 17-29 degrees C. The daily step count also tended to increase with day length, but the regression coefficient of determination attributable to step count and mean ambient temperature (r2=0.32, P<0.05) exceeded that linking the step count and day length (r2=0.13, P<0.05). The influence of other meteorological factors was small (r2<or=0.03) and of little practical significance. On days when precipitation is <1 mm, physical activity is associated more strongly with ambient temperature than with day length, duration of bright sunshine, wind speed, or relative humidity. Our findings have practical implications for health promotion efforts designed to increase the physical activity of elderly people consistently in the face of seasonal variations in environmental conditions.

Effect of ambient temperature and energy demands on digestive functions in leaf-eared mice (Phyllotis darwini) from central Chile.

The leaf-eared mouse, Phyllotis darwini, is a nocturnal rodent inhabiting the semiarid and Mediterranean habitats of northern and central Chile. Previous observations suggested that in the field, individuals may change food intake according to seasonal changes in ambient temperature. We therefore anticipated that P. darwini should increase food intake in response to lower ambient temperature. As predicted, results of food trials and digestive measurements demonstrated that P. darwini increases food intake and assimilation at lower ambient temperatures but does not increase food mean retention time. At lower ambient temperatures, individuals increase digestive tract size thus improving body mass maintenance and perhaps survival during winter.

Reproductive seasonality of the bush rat (Rattus fuscipes greyi) South Australia

The reproductive seasonality of the bush rat (Rattus fuscipes greyi) was investigated in Scott Creek Conservation Park near Adelaide, South Australia, by catch and release trapping conducted at irregular intervals over a 4-year period in a population of higher density than previously reported for this species. A seasonal pattern in breeding activity was observed with the production of young in spring and summer (October-February) with a peak in December. There was seasonal variation in the testicular index of males with minimal values from April to June. Some animals may have retained the ability to mate throughout the year but there was no evidence of offspring surviving from any winter matings. Differences were seen in the timing and intensity of the non-breeding season between years. Possible causes of reproductive seasonality were seasonal changes in vegetative growth and the abundance of fungi and insects and predictive cues provided by seasonal changes in ambient temperature and photoperiod.

Thermal acclimation and whole-plant carbon balance in Zostera marina L. (eelgrass)

Thermal acclimation in eelgrass Zostera marina L. was investigated in laboratory experiments after growing plants at 10 and 20°C for 21 days under a 12:12 L:D regime. Metabolic rates showed significant shifts in short-term response to temperature in leaves and roots. Growth rates, tissue carbohydrate concentrations and metabolic rates measured at the two growth temperatures were statistically identical, indicating that thermal acclimation was essentially complete at these temperatures. When measured at p O 2 values high enough to achieve capacity rates of respiration, thermal responses of respiration ( Q 10) were lower than previously reported while the thermal response of photosynthesis (measured at p O 2 below air saturation) was similar to previous reports. Daily C budgets constructed from metabolic rate data indicated that H sat periods required for photosynthesis to balance C demand can vary from 3 to > 12 h, depending on the ratios of net photosynthesis: respiration ( P net: R) and shoot: root. Since Z. marina. shows evidence of thermal acclimation, seasonal changes in ambient temperature may not significantly affect H sat requirements and whole-plant C balance. Rapid mortality at high temperatures during summer may result instead from thermal disruption of metabolism while internal C reserves may be important in meeting C demand during winter periods of low light availability, particularly among high-latitude populations.

Computer-Simulated Growth Prediction of Replacement Pullets with Special Reference to Seasonal Changes in Feed Intake

A mathematical model for predicting the growth of replacement pullets was constructed with special reference to seasonal changes in feed intake. Assessment of the model was made by comparing the simulated performance with published values of the National Research Council (NRC, 1984) and with field data taken from the Gifu area in central Japan. An excellent fit (R2) of simulated body weight and feed intake to those data described by NRC in 1984 was obtained. When field data were compared with model-predicted values, it was found that the inclusion of the delayed feed intake response to seasonal changes in ambient temperature (with values ranging from 5 to 6 wk) remarkably improved the prediction for feed intake, but only to a small extent for body weight.

Seasonal Patterns of Co 2 and Water Vapor Exchange of Juncus roemerianus Scheele in a Georgia Salt Marsh

CO2 and water vapor exchange studies of intact plants of black needle rush (Juncus roemerianus Scheele) were conducted in an undisturbed marsh community on Sapelo Island, Georgia. The seasonal patterns of the light and temperature responses of net photosynthesis, transpiration, leaf diffusive conductance, water-use efficiency and respiration were determined five times over the year. Internal resistances to CO2 uptake were also evaluated. Net photosynthesis was highest in early spring, but declined only slightly through the year. A distinct and moderate temperature optimum of net photosynthesis was observed with decreasing rates above 30 C. Leaf conductances to water vapor were similar at all seasons and were high at cooler temperatures and decreased with increasing temperature. Transpiration was relatively high and constant during all seasons. The water-use efficiency of photosynthesis was high below 25 C, but decreased sharply above that temperature. Dark respiration was relatively low. Seasonal changes reflected changes in leaf density. Decreasing stomatal conductances and increasing respiration rates reduced net photosynthesis at higher temperatures. The stomatal resistance increased and internal resistances to CO2 uptake decreased over the year, but the total resistance remained constant. The internal resistance to CO2 uptake was consistently higher than the stomatal resistance. These seasonal response patterns show that J. roemerianus is well adapted to the seasonal changes in ambient temperature and irradiance and other microenvironmental factors in the high marsh. These physiological characteristics permit this C3 species to maintain a high productivity in a seasonally hot and stressful environment.

SEASONAL PATTERNS OF CO2 AND WATER VAPOR EXCHANGE OF JUNCUS ROEMERIANUS SCHEELE IN A GEORGIA SALT MARSH

CO2 and water vapor exchange studies of intact plants of black needle rush (Juncus roemerianus Scheele) were conducted in an undisturbed marsh community on Sapelo Island, Georgia. The seasonal patterns of the light and temperature responses of net photosynthesis, transpiration, leaf diffusive conductance, water‐use efficiency and respiration were determined five times over the year. Internal resistances to CO2 uptake were also evaluated. Net photosynthesis was highest in early spring, but declined only slightly through the year. A distinct and moderate temperature optimum of net photosynthesis was observed with decreasing rates above 30 C. Leaf conductances to water vapor were similar at all seasons and were high at cooler temperatures and decreased with increasing temperature. Transpiration was relatively high and constant during all seasons. The water‐use efficiency of photosynthesis was high below 25 C, but decreased sharply above that temperature. Dark respiration was relatively low. Seasonal changes reflected changes in leaf density. Decreasing stomatal conductances and increasing respiration rates reduced net photosynthesis at higher temperatures. The stomatal resistance increased and internal resistances to CO2 uptake decreased over the year, but the total resistance remained constant. The internal resistance to CO2 uptake was consistently higher than the stomatal resistance. These seasonal response patterns show that J. roemerianus is well adapted to the seasonal changes in ambient temperature and irradiance and other microenvironmental factors in the high marsh. These physiological characteristics permit this C3 species to maintain a high productivity in a seasonally hot and stressful environment.

Seasonal temperature characteristics of supernatant malic dehydrogenase of adult and juvenile Mellita quinquiesperforata (Echinodermata: Echinoidea)

1. 1. Seasonal temperature characteristics of supernatant malic dehydrogenase of gut tissue were determined to ascertain whether there existed differences in acclimatization abilities in adult and juvenile Mellita quinquiesperforata. 2. 2. Disc electrophoresis resolved one band of supernatant and one band of particulate malic dehydrogenase. 3. 3. Translations with season in the Arrhenius plots of specific enzyme activity appear to be reflections of fluctuations in the levels of total gut protein and are non-compensatory in nature. 4. 4. Plots of apparent K m of malic dehydrogenase vs temperature of adults and juveniles are U-shaped and do not change with seasonal changes in ambient temperature. 5. 5. In the absence of profound seasonal changes in the effects of temperature on the activity or the kinetic behavior of the enzyme, there appears to be no seasonal acclimatization of supernatant malic dehydrogenase activity.

Seasonal variations in the mass and composition of brown adipose tissue in the meadow vole, Microtus pennsylvanicus

Wild meadow voles were collected each month of the year and analyzed for the mass and composition of their brown adipose tissue. The relative mass of brown adipose tissue decreased with increasing body weight in both summer and winter.Seasonal changes in the relative mass of brown adipose tissue were inversely related to seasonal changes in ambient temperature. In mature voles, the relative mass of brown adipose tissue was lowest during summer (0.5%) and increased rapidly to a level of 1.7% in early winter. Similarly, immature voles had their lowest relative mass in summer (1.0%) and increased this to 2.3% in winter. Both groups showed some decrease in the winter amount of the tissue when the subnivean environment became established. The percentage composition of brown adipose tissue with respect to water, lipid, and protein did not change significantly through the year.The results provide corroboration for laboratory studies which show that the mass and composition of brown adipose tissue are related to the requirement for cold thermogenesis. In voles, this requirement was present throughout the year and varied only in degree.

Thyroid secretion rates in grazing British and Zebu cross bred steers: Seasonal effects and relationships with growth

Marked monthly fluctuations in thyroid secretion rates and component parameters in 16 Hereford x Shorthorn, Africander x Hereford, and Brahman x Hereford steers did not follow seasonal changes in ambient temperature or day length in subtropical Queensland, but were more consistently related to changes in pasture quality. Secretion rates when the pasture was at its best were more than double those recorded when the pasture was poorest. British steers as compared with Zebu crossbreds were similar in thyroxine turnover rate, lower (P &lt; 0.01) in thyroid secretion rate, plasma protein-bound iodine (P.B.I.), and extrathyroidal thyroxine, and higher (P &lt; 0.01) in thyroxine volume of distribution. There were no breed x month interactions. Determinations of blood volumes and extracellular water volumes did not provide any explanation of differences in P.B.I. and thyroxine volume of distribution. Correlations betweefl thyroid secretion rates and body weight gains were positive (r = 0.85, P &lt; 0.01, among months; r = 0.70, P &lt; 0.01, among animals) in summer when pasture was good and gains averaged 2.06 lb per day. Correlations were negative (r = –0.78, P &lt; 0.01, among months; r = –0.43 among animals) in winter when pastures were poor and gains averaged –0.28 lb per day. Of the different components of thyroid secretion rate, P.B.I. and extrathyroidal thyroxine were superior to thyroxine turnover rate and thyroxine volume of distribution in reflecting seasonal changes in thyroid activity and its relation with growth rates. P.B.I. and body weight contributed most and thyroxine turnover rate and thyroxine volume of distribution least to differences in thyroid secretion rate between breeds and between animals within breeds.