Comparison Of Water Loss Research Articles

Tolerance and response of two honeybee species Apis cerana and Apis mellifera to high temperature and relative humidity.

The ambient temperature and relative humidity affect the metabolic and physiological responses of bees, thus affecting their life activities. However, the physiological changes in bee due to high temperature and high humidity remain poorly understood. In this study, we explored the effects of higher temperature and humidity on the epiphysiology of bees by evaluating the survival, tolerance and body water loss in two bee species (Apis cerana and Apis mellifera). We also evaluated the changes in the activity of antioxidant and detoxification enzymes in their body. We observed that under higher temperature and humidity conditions, the survival rate of A. mellifera was higher than that of A. cerana. On the other hand, a comparison of water loss between the two species revealed that A. mellifera lost more water. However, under extremely high temperature conditions, A. cerana was more tolerant than A. mellifera. Moreover, under higher temperature and humidity conditions, the activity of antioxidant and detoxification enzymes in bees was significantly increased. Overall, these results suggest that high temperatures can adversely affect bees. They not only affect the survival and water loss, but also stimulate oxidative stress in bees. However, unlike our previous understanding, high humidity can also adversely affect bees, although its effects are lower than that of temperature.

Effects of Drought on CAM and Water Relations in Plants of Peperomia carnevalii

The mechanisms underlying the drought tolerance of Peperomia carnevalii Steyermark (Piperaceae), a succulent herb growing in the understorey of seasonally dry forests, were examined. Crassulacean acid metabolism (CAM) was studied in the field and laboratory, and measurements of water status were made in plants subjected to drought in the greenhouse. Nocturnal acid accumulation and day and night-time CO2assimilation rates were greatest in watered plants and decreased in drought. The proportion of CO2recycled through CAM in droughted plants, with nocturnal CO2uptake close to zero, was higher than in watered plants. Maximum quantum yield of chlorophyll fluorescence remained unchanged during drought, but the PSII quantum yield at the photosynthetic photon flux density at which the plants were grown was significantly decreased. Leaf anatomy consists of a chlorophyll-less hydrenchyma located beneath the upper epidermis, and a two-layered mesophyll. Leaves nearer to the apex are thinner than those nearer to the base of the shoot. Drought caused a reduction in leaf thickness due to shrinkage of the hydrenchyma, but not of the mesophyll. This was associated with the occurrence of a gradient of osmotic potential between these tissues. Comparison of water loss from thin leaves of watered and droughted plants, either partly defoliated at the lower nodes or intact, suggested that water moved from the thick to the thin leaves. This process was related to the occurrence of a gradient of water potential between the thick and the thin leaves. Drought tolerance in P. carnevalii is achieved by the operation of CAM and the occurrence of water movement within and between leaves.

A comparison of water loss and gill areas in two supralittoral amphipods from New Zealand

Total gill area and gill distribution were measured for the sandhopper Talorchestia quoyana (Milne-Edwards) and the beach flea Transorchestia chiliensis (Milne-Edwards). For both species the gill structure and proportional area contributed by individual gills was similar. Gill 6 (G6) was the largest, providing 36% of the gill area in Tal. quoyana and 30% in Tr. chiliensis. The gill area/total dry weight relationships were similar, Y = 1.3 X0.79 for Tal. quoyana and 1.4 X0.78 for Tr. chiliensis. Small, medium and large amphipods survived >24 h in aerial conditions close to 100% RH at 15 °C. Rates of water loss in desiccating conditions increased with decreasing RH. Lethal water loss exceeded 30% weight loss for both species. Rate of water loss, (R) mg water loss. mg wet wt tissue. h−1 exposed to 75% RH for Tr. chiliensis was 0.21, resulting in total mortality within 2 h. Medium Tal. quoyana were the most resistant group surviving 4 h exposure to 75% RH with R = 0.08. Differences in desiccation tolerances of the two amphipods are not explained by body water content, gill area relationships or the larger maximal size of T. quoyana. Results were combined with those from other talitrids to examine the relationship between gill area, water content, desiccation habitat and oxygen consumption in aerial and aquatic conditions. There were no consistent relationship between gill area, O2 uptake and desiccation resistance. Amphipods show compensatory respiratory adaptation with individuals from all habitats, showing similar rates of oxygen uptake, either in air or in water, whichever was their most usual respiratory medium. Q10 values close to 2.0 were found in all ecomorphological groups. Sandhoppers, including Tal. quoyana, are best able to survive terrestrial conditions associated with a low humidity environment. It is concluded that the water loss characteristics of Tr. chiliensis limit its distribution on sand beaches to areas of high relative humidities.

Retrospective dry bulk density estimates from southeast Indian Ocean sediments — Comparison of water loss and chloride-ion methods

Knowledge of absolute accumulation rates permits quantitative comparison between and within sediment components from cores of differing age and lithologic character. Dry bulk density is an essential parameter in the calculation of absolute accumulation rates. Dry bulk density measurements require a wet-volume term and are best made when a core is first recovered. Such measurements were not routinely made on Eltanin cores from the southeast Indian Ocean. In an effort to recover this information we have estimated the dry bulk density of sixty samples from five Eltanin cores using a water loss method and a chloride-ion method which is independent of the state of desiccation of the cores. Based on the consistency of the results using these two independent methods we feel confident in our estimation of dry bulk density. Comparison of dry bulk density and %CaCO 3 allowed us to develop the following non-linear regression equation for estimating the dry bulk density based on %CaCO 3, a more easily and accurately measured property: =3.104x10 3(%CaCO 3) 2+2.176x10 −3(%CaCO 3)+0.430 This equation can be used to estimate dry bulk density to within ±0.097 g cm −3 , thus providing the information needed to reliably calculate absolute accumulation rates. Our Indian Ocean dry bulk density equations are different from those developed by similar techniques for the Pacific and Atlantic Oceans indicating that different lithologies necessitate the development of regional equations.

Comparison of Water Loss and Survival of Coastal Bermudagrass Stolons Harvested at Two Stages of Growth

Comparison of Water Loss and Survival of Coastal Bermudagrass Stolons Harvested at Two Stages of Growth

Water loss at Wad Medani. Part I

The severe climatic conditions under which cotton is grown in the Gezira make it desirable to establish relations between meteorological data and irrigation practice. By means of a rapid and fairly accurate balance it is practicable to measure water loss when small boxes containing moist soil are exposed for short periods and under different conditions. The scope of this method has been ascertained by preliminary experiments as to (1) the dependence of water loss on moisture content of the soil, (2) the distribution of water loss through the day, (3) the comparison of water loss from sand and from. Gezira soil, and (4) the comparison of water loss from shaded and unshaded soil. The application of data so obtained to field problems is facilitated by the fact that in respect to distribution and amount losses from soil are related to loss shown by a Piché evaporimeter. Within the canalised area alternation of irrigated and fallow land is responsible for local variations in atmospheric conditions. A daily fluctuation in the moisture content of surface soil from fallow land is recorded and may be instrumental in favourably modifying its physical properties. The heat of wetting of Gezira soil has been measured.