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Energy Budget (energy + budget)
Selected AbstractsThe Effect of Diet on the Energy Budget of the Brown Sea Cucumber, Stichopus mollis (Hutton)JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2009Kimberley H. Maxwell This study investigated the ability of the brown sea cucumber, Stichopus (Australostichopus) mollis, to grow on diets made from aquaculture waste. Weight-standardized rates (ingestion, assimilation, respiration, ammonia excretion, and fecal excretion) of small (juvenile), medium (mature), and large (mature) sea cucumbers were measured and energy budgets constructed to quantify their growth rates when offered three different diets at 14, 16, and 18 C. Three types of diet were offered: uneaten abalone food (diet A) and two types of abalone feces, one where abalone were fed 50% Macrocystis pyrifera and 50% Undaria pinnatifida macroalgae (diet B) and the other where abalone were fed 25% M. pyrifera, 25% U. pinnatifida, and 50% Adam & Amos Abalone Food, where the latter is an industry standard diet (diet C). The organic contents of the diets were much higher than natural sediments and varied such that diet A (76.40%) > diet B (54.50%) > diet C (37.00%). Diet had a significant effect on S. mollis ingestion rates, assimilation efficiencies, and consequently energy budgets and growth rates. Greater quantities of organic matter (OM) from diet A and diet B were ingested and assimilated by the sea cucumbers compared with the OM in diet C. The energy budgets indicated that after taking routine metabolism into account, all sizes of sea cucumbers had energy to allocate to growth when offered diet A and diet B, but only juveniles had energy to allocate to growth when offered diet C. Fecal excretion rates when offered diet A and diet C at 14 C were greater than those at 18 C, but neither was significantly different from that at 16 C. Ammonia excretion rates increased nonlinearly with temperature for small and medium sea cucumbers but not for large sea cucumbers. Weight-standardized respiration rates increased with temperature and unexpectedly with animal size, which may have been because of the narrow weight range of test animals biasing the results. These results suggest that industry standard type abalone waste lacks sufficient energy to meet the metabolic requirements of mature sea cucumbers but that growing juveniles on these wastes appears to be feasible and warrants further investigation. [source] Energy budget above a temperate mixed forest in northeastern ChinaHYDROLOGICAL PROCESSES, Issue 18 2007Jiabing Wu Abstract Components of the energy budget were measured continuously above a 300-year-old temperate mixed forest at the Changbaishan site, northeastern China, from 1 January to 31 December 2003, as a part of the ChinaFlux programme. The albedo values above the canopy were lower than most temperate forests, and the values for snow-covered canopy were over 50% higher than for the snow-free canopy. In winter, net radiation Rn was generally less than 5% of the summer value due to high albedo and low incoming solar radiation. The annual mean latent heat LE was 37·5 W m,2, accounting for 52% of Rn. The maximum daily evaporation was about 4·6 mm day,1 in summer. Over the year, the accumulated precipitation was 578 mm; this compares with 493 mm of evapotranspiration, which shows that more than 85% of water was returned to the atmosphere through evapotranspiration. The LE was strongly affected by the transpiration activity and increased quickly as the broadleaved trees began to foliate. The sensible heat H dropped at that time, although Rn increased. Consequently, the seasonal variation in the Bowen ratio , was clearly U-shaped, and the minimum value (0·1) occurred on a sunny day just after rain, when most of the available energy was used for evapotranspiration. Negative , values occurred occasionally in the non-growing season as a result of intensive radiative cooling and the presence of water on the surface. The , was very high (up to 13·0) in snow-covered winter, when evapotranspiration was small due to low surface temperature and available soil water. Vegetation phenology and soil moisture were the key variables controlling the available energy partitioning between H and LE. Energy budget closure averaged better than 86% on a half-hourly basis, with slightly greater closure on a daily basis. The degree of closure showed a dependence on friction velocity u*. Copyright © 2006 John Wiley & Sons, Ltd. [source] Influences of meteorological and vegetational factors on the partitioning of the energy of a rice paddy fieldHYDROLOGICAL PROCESSES, Issue 8 2005Hiroki Oue Abstract Observations made in a paddy field were analysed to show the influences of meteorological and vegetational factors on the crop's energy budget. Energy budget in the paddy field was characterized by the major partitioning to latent heat flux LE and by the negative Bowen ratio B mostly in the afternoon. Canopy resistance rc, estimated with the Penman,Monteith equation, was related to the influences of solar radiation SR, vapour pressure deficit VPD and plant height. The results demonstrated that rc could not directly account for B but that critical canopy resistance rcc, defined as the canopy resistance when B = 0, could be used to standardize rc, and that rc , rcc proved to be a good parameter to account for B. Influences of bulk stomatal response on energy partitioning were assessed as follows: the Bowen ratio dropped below zero, while the bulk stomatal aperture dwindled with the increase of VPD. In addition, stomata of a big leaf acted to promote the partitioning to LE against the rise of SR in the condition of higher VPD. Copyright © 2004 John Wiley & Sons, Ltd. [source] Energy budget of the Japanese flounder Paralichthys olivaceus (Temminck & Schlegel) larvae fed HUFA-enriched and non-enriched Artemia naupliiAQUACULTURE RESEARCH, Issue 10 2003O Sumule Abstract The energy budget of the Japanese flounder Paralichthys olivaceus (Temminck & Schlegel) larvae fed enriched (EA) and non-enriched (NEA) Artemia nauplii was determined by equating energy intake (EI) with the summation of energy channelled to faeces (F), metabolism (M), excretion (U) and growth (G). Larvae (21 days post hatching, 2.2 mg mean wet wt) were reared in six 80-L circular tanks with three replicates of 160 larvae per tank and fed EA and NEA for 20 days. EI was calculated from the energy content of consumed nauplii, M from the summation of energy for routine, feeding and active metabolisms, U from ammonia excretion and G from energy gained based on weight gain, while F was the difference between EI and the total of other components. The heat increment of larvae was calculated from the difference of O2 consumption at post-prandial and routine conditions. Except for G and F, variables were correlated to the dry body weight (W) of larvae in a power function: Y=aWb. Coefficients a and b were estimated by regression after a logarithmic transformation of the raw data. Overall, growth and survival rates of the larvae fed EA were higher than those fed NEA. For a larval flounder growing from 2 to 20 mg wet wt, the ingested energy was partitioned as follows: 22.8% to faecal loss, 38.3% to metabolism, 1.5% to urinary loss and 37.4% to growth for the EA group, whereas 35.4% to faecal loss, 28.4% to metabolism, 1.3% to urinary loss and 34.9% to growth for the NEA group. Gross conversion and assimilation efficiencies were higher, but the net conversion efficiency was lower in EA-fed larvae than NEA-fed larvae. This study suggests that the higher growth and survival rates of the EA-fed group compared with the NEA-fed group were attributed to their higher intake of essential fatty acids, higher metabolism and lower energy loss of faeces. [source] Effects of pre- and postnatal polychlorinated biphenyl exposure on metabolic rate and thyroid hormones of white-footed mice,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2001John B. French Jr. Abstract Energy budgets have proven to be a valuable tool for predicting life history from physiological data in terrestrial vertebrates, yet these concepts have not been applied to the physiological effects of contaminants. Contaminants might affect energy budgets by imposing an additional metabolic cost or by reducing the overall amount of energy taken in; either process will reduce the energy available for production (i.e., growth or reproduction). This study examined whole animal energetic effects of polychlorinated biphenyl (PCB) exposure in white-footed mice (Peromyscus leucopus). Exposure to PCBs is known to reduce concentrations of plasma thyroid hormones, and thyroid hormones exert strong control over the rate of energy metabolism in mammals. Peromyscus leucopus that were proven breeders were fed PCBs in their food at 0, 10, and 25 ppm. Through lactation, offspring were exposed to PCB from conception and were maintained on the maternal diet to adulthood. No effects were seen on energy metabolism (O2 consumption, measured in adulthood) or on growth, but there were large dose-dependent decreases in thyroid hormone concentrations, particularly T4. The apparent disparity in our data between unchanged metabolic rates and 50% reductions in T4 concentrations can be rationalized by noting that free T3 (the fraction not bound to plasma protein) in treated mice was not significantly different from controls and that metabolism is most strongly influenced by free T3. Overall, this study did not demonstrate any energetic consequences of PCB exposure in P. leucopus at dietary concentrations up to 25 ppm. [source] Effects of drying regime on microbial colonization and shredder preference in seasonal woodland wetlandsFRESHWATER BIOLOGY, Issue 3 2008MARTYN D. INKLEY Summary 1. Energy budgets of wetlands in temperate deciduous forests are dominated by terrestrially derived leaf litter that decays under different drying conditions depending on autumn precipitation. We compared decay rates and microbial colonization of maple leaves under different inundation schedules in a field experiment, and then conducted a laboratory study on shredder preference. In the field, litter bags either remained submerged (permanent), were moved to a dried part of the basin once and then returned (semi-permanent), or were alternated between wet and dry conditions for 8 weeks (temporary). 2. There was no difference in decay rates among treatments, but leaves incubated under permanent and semi-permanent conditions had higher fungal and bacterial biomass, and lower C : N ratios than those incubated under alternating drying and wetting conditions. 3. To determine the effects of these differences in litter nutritional quality on shredder preference, we conducted a laboratory preference test with larvae of leaf-shredding caddisflies that inhabit the wetland. Caddisflies spent twice as much time foraging on permanent and semi-permanent litter than on litter incubated under temporary conditions. 4. There is considerable variation among previous studies in how basin drying affects litter breakdown in wetlands, and no previous information on shredder preference. We found that frequent drying in a shallow wetland reduces the nutritional quality of leaf litter (lower microbial biomass and nitrogen content), and therefore preference by invertebrate shredders. These results suggest that inter-annual shifts in drying regime should alter detritus processing rates, and hence the mobilization of the energy and nutrients in leaf litter to the wetland food web. [source] Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the RatEXPERIMENTAL PHYSIOLOGY, Issue 3 2003Roberto Refinetti Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1% of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature. [source] Energetic trade-off between maintenance costs and flight capacity in the sand cricket (Gryllus firmus)FUNCTIONAL ECOLOGY, Issue 4 2008R. F. Nespolo Summary 1Energetic trade-offs are those compromises that appear when the energy budget of an individual's life history closely matches or exceeds the net available energy in the environment in a given moment. In these situations, two or more functions can compete and organisms face physiological decisions in order to survive and reproduce. 2In insects, one of the most costly investments is flight capacity, which increases dispersal capacity but is energetically expensive. Adult sand crickets (Gryllus firmus) can vary drastically in this capacity, being macropterous or micropterous depending on whether they exhibit flight-capable wings. However, this binary phenotype has a continuous subjacent determinant in the macropterous morph which is the mass of the muscles that power flight, the dorso-longitudinal muscles (DLM). 3Using respirometric measurements, we studied a potential trade-off between body parts, the mass of the DLM and energy metabolism (including both maximum and average metabolism). By recording the metabolic rate of c. 180 crickets and then dissecting and weighing their body parts, we took advantage of the correlational structure to infer associations between energetic and morphological variables. We found that the residual mass of the DLM shows a quadratic relationship with residual resting and average metabolism: at low DLM mass there is a negative relationship, which becomes positive at higher DLM mass. 4We suggest that this pattern of covariance is a consequence of the negative correlation between DLM mass and gonad mass, and the relative contribution of functional vs. non-functional DLM. Then, by using energetics and a combination of multivariate and correlational statistics we were able to show how two important life-history functions (i.e. Dispersal and fecundity) compete for the same resources in an insect species. [source] Energy budget above a temperate mixed forest in northeastern ChinaHYDROLOGICAL PROCESSES, Issue 18 2007Jiabing Wu Abstract Components of the energy budget were measured continuously above a 300-year-old temperate mixed forest at the Changbaishan site, northeastern China, from 1 January to 31 December 2003, as a part of the ChinaFlux programme. The albedo values above the canopy were lower than most temperate forests, and the values for snow-covered canopy were over 50% higher than for the snow-free canopy. In winter, net radiation Rn was generally less than 5% of the summer value due to high albedo and low incoming solar radiation. The annual mean latent heat LE was 37·5 W m,2, accounting for 52% of Rn. The maximum daily evaporation was about 4·6 mm day,1 in summer. Over the year, the accumulated precipitation was 578 mm; this compares with 493 mm of evapotranspiration, which shows that more than 85% of water was returned to the atmosphere through evapotranspiration. The LE was strongly affected by the transpiration activity and increased quickly as the broadleaved trees began to foliate. The sensible heat H dropped at that time, although Rn increased. Consequently, the seasonal variation in the Bowen ratio , was clearly U-shaped, and the minimum value (0·1) occurred on a sunny day just after rain, when most of the available energy was used for evapotranspiration. Negative , values occurred occasionally in the non-growing season as a result of intensive radiative cooling and the presence of water on the surface. The , was very high (up to 13·0) in snow-covered winter, when evapotranspiration was small due to low surface temperature and available soil water. Vegetation phenology and soil moisture were the key variables controlling the available energy partitioning between H and LE. Energy budget closure averaged better than 86% on a half-hourly basis, with slightly greater closure on a daily basis. The degree of closure showed a dependence on friction velocity u*. Copyright © 2006 John Wiley & Sons, Ltd. [source] Evaporation estimation on Lake Titicaca: a synthesis review and modellingHYDROLOGICAL PROCESSES, Issue 13 2007François Delclaux Abstract The aim of this study was to validate evaporation models that can be used for palaeo-reconstructions of large lake water levels. Lake Titicaca, located in a high-altitude semi-arid tropical area in the northern Andean Altiplano, was the object of this case study. As annual evaporation is about 90% of lake output, the lake water balance depends heavily on the yearly and monthly evaporation flux. At the interannual scale, evaporation estimation presents great variability, ranging from 1350 to 1900 mm year,1. It has been found that evaporation is closely related to lake rainfall by a decreasing relationship integrating the implicit effect of nebulosity and humidity. At the seasonal scale, two monthly evaporation data sets were used: pan observations and estimations derived from the lake energy budget. Comparison between these data sets shows that (i) there is one maximum per year for pan evaporation and two maxima per year for lake evaporation, and (ii) pan evaporation is greater than lake evaporation by about 100 mm year,1. These differences, mainly due to a water depth scale factor, have been simulated with a simple thermal model ,w(h, t) of a free-surface water column. This shows that pan evaporation (h = 0·20 m) is strongly correlated with direct solar radiation, whereas the additional maximum of lake evaporation (h = 40 m) is related to the heat restitution towards the atmosphere from the water body at the end of summer. Finally, five monthly evaporation models were tested in order to obtain the optimal efficiency/complexity ratio. When the forcing variables are limited to those that are most readily available in the past, i.e. air temperature and solar radiation, the best results are obtained with the radiative Abtew model (r = 0·70) and with the Makkink radiative/air temperature model (r = 0·67). Copyright © 2007 John Wiley & Sons, Ltd. [source] Simulating the response of a closed-basin lake to recent climate changes in tropical West Africa (Lake Bosumtwi, Ghana)HYDROLOGICAL PROCESSES, Issue 13 2007Timothy M. Shanahan Abstract Historical changes in the level of Lake Bosumtwi, Ghana, have been simulated using a catchment-scale hydrological model in order to assess the importance of changes in climate and land use on lake water balance on a monthly basis for the period 1939,2004. Several commonly used models for computing evaporation in data-sparse regions are compared, including the Penman, the energy budget, and the Priestley,Taylor methods. Based on a comparison with recorded lake level variations, the model with the energy-budget evaporation model subcomponent is most effective at reproducing observed lake level variations using regional climate records. A sensitivity analysis using this model indicates that Lake Bosumtwi is highly sensitive to changes in precipitation, cloudiness and temperature. However, the model is also sensitive to changes in runoff related to vegetation, and this factor needs to be considered in simulating lake level variations. Both interannual and longer-term changes in lake level over the last 65 years appear to have been caused primarily by changes in precipitation, though the model also suggests that the drop in lake level over the last few decades has been moderated by changes in cloudiness and temperature over that time. Based on its effectiveness at simulating the magnitude and rate of lake level response to changing climate over the historical record, this model offers a potential future opportunity to examine the palaeoclimatic factors causing past lake level fluctuations preserved in the geological record at Lake Bosumtwi. Copyright © 2006 John Wiley & Sons, Ltd. [source] Influences of meteorological and vegetational factors on the partitioning of the energy of a rice paddy fieldHYDROLOGICAL PROCESSES, Issue 8 2005Hiroki Oue Abstract Observations made in a paddy field were analysed to show the influences of meteorological and vegetational factors on the crop's energy budget. Energy budget in the paddy field was characterized by the major partitioning to latent heat flux LE and by the negative Bowen ratio B mostly in the afternoon. Canopy resistance rc, estimated with the Penman,Monteith equation, was related to the influences of solar radiation SR, vapour pressure deficit VPD and plant height. The results demonstrated that rc could not directly account for B but that critical canopy resistance rcc, defined as the canopy resistance when B = 0, could be used to standardize rc, and that rc , rcc proved to be a good parameter to account for B. Influences of bulk stomatal response on energy partitioning were assessed as follows: the Bowen ratio dropped below zero, while the bulk stomatal aperture dwindled with the increase of VPD. In addition, stomata of a big leaf acted to promote the partitioning to LE against the rise of SR in the condition of higher VPD. Copyright © 2004 John Wiley & Sons, Ltd. [source] Regional climate modulates the canopy mosaic of favourable and risky microclimates for insectsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SYLVAIN PINCEBOURDE Summary 1,One major gap in our ability to predict the impacts of climate change is a quantitative analysis of temperatures experienced by organisms under natural conditions. We developed a framework to describe and quantify the impacts of local climate on the mosaic of microclimates and physiological states of insects within tree canopies. This approach was applied to a leaf mining moth feeding on apple leaf tissues. 2,Canopy geometry was explicitly considered by mapping the 3D position and orientation of more than 26 000 leaves in an apple tree. Four published models for canopy radiation interception, energy budget of leaves and mines, body temperature and developmental rate of the leaf miner were integrated. Model predictions were compared with actual microclimate temperatures. The biophysical model accurately predicted temperature within mines at different positions within the tree crown. 3,Field temperature measurements indicated that leaf and mine temperature patterns differ according to the regional climatic conditions (cloudy or sunny) and depending on their location within the canopy. Mines in the sun can be warmer than those in the shade by several degrees and the heterogeneity of mine temperature was incremented by 120%, compared with that of leaf temperature. 4.,The integrated model was used to explore the impact of both warm and exceptionally hot climatic conditions recorded during a heat wave on the microclimate heterogeneity at canopy scale. During warm conditions, larvae in sunlight-exposed mines experienced nearly optimal growth conditions compared with those within shaded mines. The developmental rate was increased by almost 50% in the sunny microhabitat compared with the shaded location. Larvae, however, experienced optimal temperatures for their development inside shaded mines during extreme climatic conditions, whereas larvae in exposed mines were overheating, leading to major risks of mortality. 5,Tree canopies act as both magnifiers and reducers of the climatic regime experienced in open air outside canopies. Favourable and risky spots within the canopy do change as a function of the climatic conditions at the regional scale. The shifting nature of the mosaic of suitable and risky habitats may explain the observed uniform distribution of leaf miners within tree canopies. [source] From molecules to ecosystems through dynamic energy budget modelsJOURNAL OF ANIMAL ECOLOGY, Issue 6 2000R. M. Nisbet Summary 1. Dynamic energy budget (DEB) models describe how individuals acquire and utilize energy, and can serve as a link between different levels of biological organization. 2. We describe the formulation and testing of DEB models, and show how the dynamics of individual organisms link to molecular processes, to population dynamics, and (more tenuously) to ecosystem dynamics. 3. DEB models offer mechanistic explanations of body-size scaling relationships. 4. DEB models constitute powerful tools for applications in toxicology and biotechnology. 5. Challenging questions arise when linking DEB models with evolutionary theory. [source] Size-independent growth in fishes: patterns, models and metricsJOURNAL OF FISH BIOLOGY, Issue 10 2008D. B. Sigourney A combination of a dynamic energy budget (DEB) model, field data on Atlantic salmon Salmo salar and brown trout Salmo trutta and laboratory data on Atlantic salmon was used to assess the underlying assumptions of three different metrics of growth including specific growth rate (G), standardized mass-specific growth rate (GS) and absolute growth rate in length (GL) in salmonids. Close agreement was found between predictions of the DEB model and the assumptions of linear growth in length and parabolic growth in mass. Field data comparing spring growth rates of age 1+ year and 2+ year Atlantic salmon demonstrated that in all years the larger age 2+ year fish exhibited a significantly lower G, but differences in growth in terms of GS and GL depended on the year examined. For brown trout, larger age 2+ year fish also consistently exhibited slower growth rates in terms of G but grew at similar rates as age 1+ year fish in terms of GS and GL. Laboratory results revealed that during the age 0+ year (autumn) the divergence in growth between future Atlantic salmon smolts and non-smolts was similar in terms of all three metrics with smolts displaying higher growth than non-smolts, however, both GS and GL indicated that smolts maintain relatively fast growth into the late autumn where G suggested that both smolts and non-smolts exhibit a sharp decrease in growth from October to November. During the spring, patterns of growth in length were significantly decoupled from patterns in growth in mass. Smolts maintained relatively fast growth though April in length but not in mass. These results suggest GS can be a useful alternative to G as a size-independent measure of growth rate in immature salmonids. In addition, during certain growth stanzas, GS may be highly correlated with GL. The decoupling of growth in mass from growth in length over ontogeny, however, may necessitate a combination of metrics to adequately describe variation in growth depending on ontogenetic stage particularly if life histories differ. [source] Relationships between metabolic rate, muscle electromyograms and swim performance of adult chinook salmonJOURNAL OF FISH BIOLOGY, Issue 4 2003D. R. Geist Oxygen consumption rates of adult spring chinook salmon Oncorhynchus tshawytscha increased with swim speed and, depending on temperature and fish mass, ranged from 609 mg O2 h,1 at 30 cm s,1 (c. 0·5 BL s,1) to 3347 mg O2 h,1 at 170 cm s,1 (c. 2·3 BL s,1). Corrected for fish mass, these values ranged from 122 to 670 mg O2 kg,1 h,1, and were similar to other Oncorhynchus species. At all temperatures (8, 12·5 and 17° C), maximum oxygen consumption values levelled off and slightly declined with increasing swim speed >170 cm s,1, and a third-order polynomial regression model fitted the data best. The upper critical swim speed (Ucrit) of fish tested at two laboratories averaged 155 cm s,1 (2·1 BL s,1), but Ucrit of fish tested at the Pacific Northwest National Laboratory were significantly higher (mean 165 cm s,1) than those from fish tested at the Columbia River Research Laboratory (mean 140 cm s,1). Swim trials using fish that had electromyogram (EMG) transmitters implanted in them suggested that at a swim speed of c. 135 cm s,1, red muscle EMG pulse rates slowed and white muscle EMG pulse rates increased. Although there was significant variation between individual fish, this swim speed was c. 80% of the Ucrit for the fish used in the EMG trials (mean Ucrit 168·2 cm s,1). Bioenergetic modelling of the upstream migration of adult chinook salmon should consider incorporating an anaerobic fraction of the energy budget when swim speeds are ,80% of the Ucrit. [source] EXCHANGES OF INFORMATION, ENERGY & MATERIALS IN SYMBIOSESJOURNAL OF PHYCOLOGY, Issue 2000J.A. Raven Symbiosis is important in the cell and environmental biology of algae. Some examples involving the author and numerous collaborators include: 1) chloroplasts of eukaryotic algae arose from endosymbioses. Plastids are incapable of independent existence; most of the genes of the cyanobacterial photobiont have been lost, and the majority of the rest have been transferred to the nuclear genome. Some of the genes retained by the plastid are those whose transcription is controlled by environmental cues transduced by the organelle. The general trend is for organelle genes to be transferred to the nucleus, escaping plastid redox activities generating mutagenic free radicals; 2) symbioses involving potentially free-living photobionts include marine lichens and sponges with cyanobacterial symbionts. For the lichen, Lichina, inorganic carbon acquisition appears to involve inorganic carbon transport by the mycobiont, and for the sponge, Cymbastella, the flagellar activity of the sponge is probably important for inorganic carbon supply to the photobiont; 3) the Australasian fucalean, Notheia, is an obligate epiphyte on the fucaleans, Hormosira and Xiphophora; the four species involved all contain the hexitol, altritol. Notheia anomala is known to be phyletically-distant from the other five altritol-containing species. Can Notheia synthesize altritol, or is it obtained from the phorophyte?; 4) Sacoglossan gastropods retain kleptoplastids (not strictly symbionts) from ulvophycean (or rhodophycean) marine algae. Analyses of the natural abundance of stable carbon isotopes suggest significant contribution of kleptoplastid photosynthesis to the carbon and energy budget of the mollusks. [source] Formation of hard very high energy gamma-ray spectra of blazars due to internal photon,photon absorptionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008Felix A. Aharonian ABSTRACT The energy spectra of TeV gamma-rays from blazars, after being corrected for intergalatic absorption in the extragalactic background light (EBL), appear unusually hard, a fact that poses challenges to the conventional models of particle acceleration in TeV blazars and/or to the EBL models. In this paper, we show that the internal absorption of gamma-rays caused by interactions with dense narrow-band radiation fields in the vicinity of compact gamma-ray production regions can lead to the formation of gamma-ray spectra of an almost arbitrary hardness. This allows significant relaxation of the current tight constraints on particle acceleration and radiation models, although at the expense of enhanced requirements to the available non-thermal energy budget. The latter, however, is not a critical issue, as long as it can be largely compensated by the Doppler boosting, assuming large (>10) Doppler factors of the relativistically moving gamma-ray production regions. The suggested scenario of formation of hard gamma-ray spectra predicts detectable synchrotron radiation of secondary electron,positron pairs which might require a revision of the current ,standard paradigm' of spectral energy distributions of gamma-ray blazars. If the primary gamma-rays are of hadronic origin related to pp or p, interactions, the ,internal gamma-ray absorption' model predicts neutrino fluxes close to the detection threshold of the next generation high-energy neutrino detectors. [source] Pooled energy budget and human life historyAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Meredith W. Reiches Human life history contains a series of paradoxes not easily explained by classical life history theory. Although overall reproductive output is higher than in related primates, juvenile growth is slower and age-specific reproductive rates decline faster with age. A simple energetic model would predict that growth and reproductive rates should be positively correlated and that reproductive effort should not decelerate with age. The pattern of negative correlations in humans suggest the presence of trade-offs among peak reproductive rate, childhood growth, and reproductive rate at older ages. To address this puzzle, we propose a synthesis of reproductive ecology and behavioral ecology focused on intra- and inter-somatic energy transfers. This integration includes three concepts: the mother as final common pathway through which energy must pass to result in offspring; a distinction between direct and indirect reproductive effort, proposing the latter as a novel net energy allocation category relative to growth and direct reproductive effort; and a pooled energy budget representing the energetic contributions and withdrawals of all members of a breeding community. Individuals at all reproductive life stages are considered in light of their contributions to the pooled energy budget. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] Reproduction and lifespan: Trade-offs, overall energy budgets, intergenerational costs, and costs neglected by research,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Grazyna Jasienska In human females allocation of resources to support reproduction may cause their insufficient supply to other metabolic functions, resulting in compromised physiology, increased risks of diseases and, consequently, reduced lifespan. While many studies on both historical and contemporary populations show that women with high fertility indeed have shorter lifespans. This relationship is far from universal: a lack of correlation between fertility and lifespan, or even an increased lifespan of women with high fertility have also been documented. Reduced lifespan in women with high fertility may be undetectable due to methodological weaknesses of research or it may be truly absent, and its absence may be explained from biological principles. I will discuss the following reasons for a lack of the negative relationship, described in some demographic studies, between the number of children and lifespan in women: (1) Number of children is only a proxy of the total costs of reproduction and the cost of breastfeeding is often higher than the pregnancy cost but is often not taken into account. (2) Costs of reproduction can be interpreted in a meaningful way only when they are analyzed in relation to the overall energy budget of the woman. (3) Trade-offs between risks of different diseases due to reproduction yield different mortality predictions depending on the socio-economic status of the studied populations. (4) Costs of reproduction are related not only to having children but also to having grandchildren. Such intergenerational costs should be included in analysis of trade-offs between costs of reproduction and longevity. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] Investigations on the digestibility and metabolizability of the major nutrients and energy of maize leaves and barnyard grass in grass carp (Ctenopharyngodon idella)AQUACULTURE NUTRITION, Issue 3 2010E.B. DONGMEZA Abstract In the uplands of northern Vietnam, culture of grass carp contributes significantly to income and household food security of Black Thai farmers. Maize is one of the most important upland crops and barnyard grass is the most important weed in the paddy rice fields. Thus, these are frequently used by small-scale fish farmers as fish feed. An 8-week feeding trial was conducted simultaneously in a recirculation and in a respirometric system to determine the digestibility and metabolizability of the nutrients of maize leaves and barnyard grass, to assess their crude protein, lipid and energy conversion and to estimate the energy allocation in grass carp. The following diets were used: diet ,A' (reference diet) containing 39% crude protein with 19.8 MJ kg,1 gross energy; diets ,B', ,C' and ,D', which contained the same amount of the reference diet as the control diet, supplemented with a known amount of dried barnyard grass, dried maize leaves or fresh maize leaves, respectively. Five fish were assigned to each treatment in each experimental unit. Reference and test diets were fed to fish and faecal samples were collected and the oxygen consumption was measured in order to set up an energy budget of the fish over the whole experimental period. The weekly development of the body weight was recorded. The body weight gain of the fish fed diet D was significantly higher than that of the group fed diet A, which also in turn was significantly higher than that of fish fed diet B or C. The apparent digestibility coefficients (ADC) of nutrients and gross energy for the different experimental diets in fish kept in the aquaria were, for diets A, B, C and D respectively, 94.1%, 60.9%, 70.5% and 84.7% for protein, 91.3%, 60.7%, 76.8% and 71.8% for lipid; 95.9%, 44.5%, 60.6% and 69.1% for gross energy. The partial ADC of plant leaf ingredients were determined and barnyard grass and dried maize leaves were found to be not only poorly digestible but having negative impact on the digestibility of the reference diet, while fresh maize leaves were well digested. The results of the present study indicated that fresh maize leaves have a good potential to be used as supplement in diets for grass carp. [source] Feeding and growth in captivity of the octopus Enteroctopus megalocyathus Gould, 1852AQUACULTURE RESEARCH, Issue 6 2006Margarita C Pérez Abstract The effect of diet on the growth and survival in captivity of the octopus Enteroctopus megalocyathus Gould, 1852 was researched to establish culture potential. This is one of two commercially important octopus species that inhabit the Chilean coast. A positive energy budget, averaging 678 J day,1 g of dry weight (dw), was recorded in specimens maintained in tanks and fed ad libitum on a diet of three species of crustacean decapods. On the other hand, the energy budget of octopus specimens fed on the mussel Mytilus chilensis (Hupé) was negative, averaging ,250.90 J day,1 g dw,1. Ingestion rates varied between diets (t=46.45; d.f.=18; P<0.001), but no variations were recorded in energy loss resulting from metabolism (t=0.67; d.f.=16; P>0.05) or ammonia excretion (t=1.39; d.f.=16; P>0.05). An average instantaneous growth rate (IGR) of between 1.96% and 0.49% was recorded in specimens fed on crustaceans, depending on the size of the octopus and the period of time. The IGR in specimens fed on mussels was ,0.32±0.05. The IGR of specimens fed on crustaceans and maintained in suspended systems was 1.36±0.9%. The mean mortality with crustacean and mussel diets was 11.07±5.5% and 74±1% respectively. The results indicate that E. megalocyathus can survive and grow in captivity, both in tanks and in suspended systems, when fed on a diet of crustaceans. [source] Enhanced energy efficiency and reliability of telecommunication equipment with the introduction of novel air cooled thermal architecturesBELL LABS TECHNICAL JOURNAL, Issue 2 2010Domhnaill Hernon In the past, thermal management was an afterthought in the design process of a product owing to the fact that heat dissipation loads and densities were minute and did not adversely affect component reliability. In fact, it may be stated that, historically, the sole purpose of thermal management was to ensure component operation below a critical temperature thereby providing reliable equipment operation for a given time period. However, this mindset has evolved in recent years given current economic and energy concerns. Climate change concern owing to vast green house gas emissions, increasing fuel and electricity costs, and a general trend towards energy-efficiency awareness has promoted thermal management to the forefront of "green" innovation within the information and communications technology (ICT) sector. If one considers the fact that up to 50 percent of the energy budget of a data center is spent on cooling equipment and that two percent of the United States' annual electricity is consumed by telecommunications equipment, it becomes obvious that thermal management has a key role to play in the development of eco-sustainable solutions. This paper will provide an overview of the importance of thermal management for reliable component operation and highlight the research areas where improved energy efficiency can be achieved. Novel air-cooled thermal solutions demonstrating significant energy savings and improved reliability over existing technology will be presented including three dimensional (3D) monolithic heat sinks and vortex generators. © 2010 Alcatel-Lucent. [source] Quantitative steps in symbiogenesis and the evolution of homeostasisBIOLOGICAL REVIEWS, Issue 3 2003S. A. L. M. KOOIJMAN ABSTRACT The merging of two independent populations of heterotrophs and autotrophs into a single population of mixotrophs has occurred frequently in evolutionary history. It is an example of a wide class of related phenomena, known as symbiogenesis. The physiological basis is almost always (reciprocal) syntrophy, where each species uses the products of the other species. Symbiogenesis can repeat itself after specialization on particular assimilatory substrates. We discuss quantitative aspects and delineate eight steps from two free-living interacting populations to a single fully integrated endosymbiotic one. The whole process of gradual interlocking of the two populations could be mimicked by incremental changes of particular parameter values. The role of products gradually changes from an ecological to a physiological one. We found conditions where the free-living, epibiotic and endobiotic populations of symbionts can co-exist, as well as conditions where the endobiotic symbionts outcompete other symbionts. Our population dynamical analyses give new insights into the evolution of cellular homeostasis. We show how structural biomass with a constant chemical composition can evolve in a chemically varying environment if the parameters for the formation of products satisfy simple constraints. No additional regulation mechanisms are required for homeostasis within the context of the dynamic energy budget (DEB) theory for the uptake and use of substrates by organisms. The DEB model appears to be closed under endosymbiosis. This means that when each free-living partner follows DEB rules for substrate uptake and use, and they become engaged in an endosymbiotic relationship, a gradual transition to a single fully integrated system is possible that again follows DEB rules for substrate uptake and use. [source] An economic model of the limits to foraging range in central place foragers with numerical solutions for bumblebeesECOLOGICAL ENTOMOLOGY, Issue 3 2000James E. Cresswell Summary 1. A model is described that evaluates the maximum economic foraging range in central place foragers by using optimality criteria to discriminate between foraging sites at different distances from the forager's central place. 2. The basic model can be varied to suit foragers that optimise either their rate of net energy uptake or their foraging efficiency. 3. The model requires specification of the time and energy budgets of travel and foraging, and of the rewards obtainable at potential foraging sites. 4. The specific case of bumblebees, whose foraging ranges are poorly known, is considered. 5. Numerical solutions of the model for parameter values that represent bumblebees and their forage predict economic foraging ranges exceeding several kilometres. The model demonstrates that economics alone can explain extensive flight ranges in bees. [source] Effects of pre- and postnatal polychlorinated biphenyl exposure on metabolic rate and thyroid hormones of white-footed mice,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2001John B. French Jr. Abstract Energy budgets have proven to be a valuable tool for predicting life history from physiological data in terrestrial vertebrates, yet these concepts have not been applied to the physiological effects of contaminants. Contaminants might affect energy budgets by imposing an additional metabolic cost or by reducing the overall amount of energy taken in; either process will reduce the energy available for production (i.e., growth or reproduction). This study examined whole animal energetic effects of polychlorinated biphenyl (PCB) exposure in white-footed mice (Peromyscus leucopus). Exposure to PCBs is known to reduce concentrations of plasma thyroid hormones, and thyroid hormones exert strong control over the rate of energy metabolism in mammals. Peromyscus leucopus that were proven breeders were fed PCBs in their food at 0, 10, and 25 ppm. Through lactation, offspring were exposed to PCB from conception and were maintained on the maternal diet to adulthood. No effects were seen on energy metabolism (O2 consumption, measured in adulthood) or on growth, but there were large dose-dependent decreases in thyroid hormone concentrations, particularly T4. The apparent disparity in our data between unchanged metabolic rates and 50% reductions in T4 concentrations can be rationalized by noting that free T3 (the fraction not bound to plasma protein) in treated mice was not significantly different from controls and that metabolism is most strongly influenced by free T3. Overall, this study did not demonstrate any energetic consequences of PCB exposure in P. leucopus at dietary concentrations up to 25 ppm. [source] Potential effects of warming and drying on peatland plant community compositionGLOBAL CHANGE BIOLOGY, Issue 2 2003Jake F. Weltzin Abstract Boreal peatlands may be particularly vulnerable to climate change, because temperature regimes that currently constrain biological activity in these regions are predicted to increase substantially within the next century. Changes in peatland plant community composition in response to climate change may alter nutrient availability, energy budgets, trace gas fluxes, and carbon storage. We investigated plant community response to warming and drying in a field mesocosm experiment in northern Minnesota, USA. Large intact soil monoliths removed from a bog and a fen received three infrared warming treatments crossed with three water-table treatments (n = 3) for five years. Foliar cover of each species was estimated annually. In the bog, increases in soil temperature and decreases in water-table elevation increased cover of shrubs by 50% and decreased cover of graminoids by 50%. The response of shrubs to warming was distinctly species-specific, and ranged from increases (for Andromeda glaucophylla) to decreases (for Kalmia polifolia). In the fens, changes in plant cover were driven primarily by changes in water-table elevation, and responses were species- and lifeform-specific: increases in water-table elevation increased cover of graminoids , in particular Carex lasiocarpa and Carex livida, as well as mosses. In contrast, decreases in water-table elevation increased cover of shrubs, in particular A. glaucophylla and Chamaedaphne calyculata. The differential and sometimes opposite response of species and lifeforms to the treatments suggest that the structure and function of both bog and fen plant communities will change , in different directions or at different magnitudes , in response to warming and/or changes in water-table elevation that may accompany regional or global climate change. [source] Above-stream microclimate and stream surface energy exchanges in a wildfire-disturbed riparian zoneHYDROLOGICAL PROCESSES, Issue 17 2010J. A. Leach Abstract Stream temperature and riparian microclimate were characterized for a 1·5 km wildfire-disturbed reach of Fishtrap Creek, located north of Kamloops, British Columbia. A deterministic net radiation model was developed using hemispherical canopy images coupled with on-site microclimate measurements. Modelled net radiation agreed reasonably with measured net radiation. Air temperature and humidity measured at two locations above the stream, separated by 900 m, were generally similar, whereas wind speed was poorly correlated between the two sites. Modelled net radiation varied considerably along the reach, and measurements at a single location did not provide a reliable estimate of the modelled reach average. During summer, net radiation dominated the surface heat exchanges, particularly because the sensible and latent heat fluxes were normally of opposite sign and thus tended to cancel each other. All surface heat fluxes shifted to negative values in autumn and were of similar magnitude through winter. In March, net radiation became positive, but heat gains were cancelled by sensible and latent heat fluxes, which remained negative. A modelling exercise using three canopy cover scenarios (current, simulated pre-wildfire and simulated complete vegetation removal) showed that net radiation under the standing dead trees was double that modelled for the pre-fire canopy cover. However, post-disturbance standing dead trees reduce daytime net radiation reaching the stream surface by one-third compared with complete vegetation removal. The results of this study have highlighted the need to account for reach-scale spatial variability of energy exchange processes, especially net radiation, when modelling stream energy budgets. Copyright © 2010 John Wiley & Sons, Ltd. [source] The Effect of Diet on the Energy Budget of the Brown Sea Cucumber, Stichopus mollis (Hutton)JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2009Kimberley H. Maxwell This study investigated the ability of the brown sea cucumber, Stichopus (Australostichopus) mollis, to grow on diets made from aquaculture waste. Weight-standardized rates (ingestion, assimilation, respiration, ammonia excretion, and fecal excretion) of small (juvenile), medium (mature), and large (mature) sea cucumbers were measured and energy budgets constructed to quantify their growth rates when offered three different diets at 14, 16, and 18 C. Three types of diet were offered: uneaten abalone food (diet A) and two types of abalone feces, one where abalone were fed 50% Macrocystis pyrifera and 50% Undaria pinnatifida macroalgae (diet B) and the other where abalone were fed 25% M. pyrifera, 25% U. pinnatifida, and 50% Adam & Amos Abalone Food, where the latter is an industry standard diet (diet C). The organic contents of the diets were much higher than natural sediments and varied such that diet A (76.40%) > diet B (54.50%) > diet C (37.00%). Diet had a significant effect on S. mollis ingestion rates, assimilation efficiencies, and consequently energy budgets and growth rates. Greater quantities of organic matter (OM) from diet A and diet B were ingested and assimilated by the sea cucumbers compared with the OM in diet C. The energy budgets indicated that after taking routine metabolism into account, all sizes of sea cucumbers had energy to allocate to growth when offered diet A and diet B, but only juveniles had energy to allocate to growth when offered diet C. Fecal excretion rates when offered diet A and diet C at 14 C were greater than those at 18 C, but neither was significantly different from that at 16 C. Ammonia excretion rates increased nonlinearly with temperature for small and medium sea cucumbers but not for large sea cucumbers. Weight-standardized respiration rates increased with temperature and unexpectedly with animal size, which may have been because of the narrow weight range of test animals biasing the results. These results suggest that industry standard type abalone waste lacks sufficient energy to meet the metabolic requirements of mature sea cucumbers but that growing juveniles on these wastes appears to be feasible and warrants further investigation. [source] XMM,Newton observations of warm absorbers in PG quasarsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2004C. E. Ashton ABSTRACT We present XMM,Newton European Photon Imaging Camera observations of warm absorbers in the quasars PG 1114+445 and PG 1309+355, both of which exhibit evidence for absorption by warm material in the line of sight. We find the absorption in PG 1114+445 to be in two phases, a ,hot' phase with a log ionization parameter, ,, of 2.57, and a ,cooler' phase with log ,= 0.83; an unresolved transition array (UTA) of M-shell iron is observed in the cooler phase. The absorption in this quasar is similar to that observed in the Seyfert 1 NGC 3783. The absorption in PG 1309+355 consists of a single phase, with log ,= 1.87. The absorbing gas lies at distances of 1018,1022 cm from the continuum radiation sources in these active galactic nuclei (AGN), which suggests that it could originate in a wind emanating from a molecular torus. We derive distances assuming that these X-ray warm absorbers have the same velocity as the ultraviolet warm absorbers observed in these quasars. The distances to the warm absorbers from the central continuum source scale approximately with the square root of the AGN ionizing luminosity, a result consistent with the warm absorber originating as a torus wind. The kinetic luminosities of these outflowing absorbers represent insignificant fractions (<10,3) of the energy budgets of the AGN. [source] | |||||||||||||