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Daily Rate (daily + rate)
Selected AbstractsSex ratio and maturity indicate the local dispersal and mortality of adult stonefliesFRESHWATER BIOLOGY, Issue 8 2006I. PETERSEN Summary 1.,Despite a recent upsurge in interest, there remains remarkably little information about the dispersal and survival of the adults of most stream-dwelling insects, although this is a basic requirement for understanding their long-term population dynamics. 2.,Using Malaise traps for a whole annual flight period, we captured adult stoneflies (Leuctra nigra) along transects perpendicular to three upland Welsh streams. We assessed spatial and temporal patterns in sex ratio to infer local dispersal and, using maturity as an age marker, estimated the mortality of adult females. 3.,Nearly all adult stoneflies (99%) were taken in the period 26 April,23 July, and the onset of the male and female flight periods was the same. Most males (90%) had been caught by late June. Females were classified as immature (without ripe eggs) or mature, and 90% of immature females had been caught by mid-late June (depending on catchment). As immature females declined in the catch, mature females increased, 10% having been caught by late-May to early June and 90% by early to mid-July. The median catches of immature and mature females were separated by 32 days in all three catchments. 4.,There was a female bias in the sex ratio overall, which increased as time passed and was attributable partially to the greater longevity of females. Late in the flight period, however, female bias was also greater near the stream channel implying a return of mature females (but not males) from the riparian vegetation, presumably to oviposit. 5.,The number of mature females was less than the number of immatures in two of the three channels. Over all three catchments, the overall mortality of females over the 32 days taken to mature was estimated at 29%, equivalent to an exponential daily rate of 1.1% day,1. The apparently negative mortality rate in one catchment (i.e. more matures than immatures being caught) could be due to an influx of adult females from elsewhere along the channel to oviposit. 6.,Natural markers of age and population structure, such as sex ratio and female maturity, thus enabled us to detect a return of females to the stream to oviposit, after prior limited dispersal into the riparian zone, and to infer longitudinal movements in search of suitable sites. We were also able to estimate mortality in the field. Such natural markers seem to have been underexploited in the study of adult aquatic insects. [source] Ingestion patterns and daily energy intake on a sugary diet: the Red Lory Eos bornea and the Malachite Sunbird Nectarinia famosaIBIS, Issue 3 2000COLLEEN T. DOWNS This study examines whether nectarivorous birds regulate daily energy intake as proposed by Lloyd in 1991. Two Old World nectarivorous species, a large non-passerine, the Red Lory Eos bornea, and a small passerine, the Malachite Sunbird Nectarinia famosa, were fed 0.25 mol/1 sucrose (9%), 0.73 mol/1 sucrose [24%] or 0.73 mol/1 glucose in separate laboratory trials to determine hourly and overall daily rate of sugar intake and consumption. Overall daily energy intake rates of the Malachite Sunbird and the Red Lory support the hypothesis of regulated energy intake for nectarivorous Old World birds. However, the species differ in their ingestion patterns through the day. The Red Lory ingests large volumes initially, regardless of sugar type. This is possibly a consequence of their large size and having a crop in which food can be stored. The Malachite Sunbird showed more regular hourly consumption through the day, and no change in mass during the day. Intake rates of both species were greater on lower sugar concentrations. [source] Quantitative Protein Requirements of the Edible Snail Pomacea urceus (Muller)JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2004Indar W. Ramnarine Six isocaloric, semi-purified diets containing 15, 20, 25, 30, 35, and 40% crude protein were formulated and fed to juvenile Pomacea urceus (mean length 34.8 mm, mean weight 7.35 g) at the daily rate of 4% biomass over an 18-wk period. The best weight gain of 230% was obtained with the test diet containing 30% crude protein, but was not significantly different from the weight gain of 228% obtained with the 20% protein diet. A lower feed conversion ratio (1.77 compared with 1.90) was obtained with the test diet containing 20% crude protein. A diet containing 20% crude protein is recommended for the culture of Pomacea urceus. [source] Growth and maintenance respiration for individual plants in hierarchically structured canopies of Medicago sativa and Helianthus annuus: the contribution of current and old assimilatesNEW PHYTOLOGIST, Issue 2 2004Markus Lötscher Summary ,,Respiratory costs of Medicago sativa and Helianthus annuus individuals growing in hierarchically structured stands in a controlled environment were analysed with regard to the daily rate of carbon (C) assimilation. ,,Net assimilation of new C (An, g C d,1) and respiration rates of new (Rnew, g C d,1) and old C (Rold, g C d,1) were assessed by 13CO2 labelling and gas exchange measurements. ,,Specific respiration rate of old C (rold, g C g,1 C d,1) decreased exponentially with increasing shoot biomass, but was not affected by the instantaneous relative growth rate (,wi). The growth coefficient g (Rnew: An) was c. 0.32. In the most severely shaded subordinate plants, g was < 0.2, but low g stimulated rold. The contribution of Rnew to total respiraton (fR, new) and the carbon use efficiency CUE (1 , R/(An +Rnew)) were c. 0.68 and 0.62 for ,wi > 0.1, respectively. For ,wi < 0.1, fR, new and CUE decreased with decreasing ,wi in both dominant and subordinate plants. ,,The results suggest that Rold was closely related to maintenance, whereas Rnew was primarily involved in growth. [source] Effects of varying dietary fatty acid profile on growth performance, fatty acid, body and tissue composition of juvenile pike perch (Sander lucioperca)AQUACULTURE NUTRITION, Issue 6 2005C. SCHULZ Abstract Pike perch (Sander lucioperca) has been identified as specie destined to diverse European inland aquaculture, but knowledge on the nutritional requirements is weak. Therefore, we investigated the effect of varying dietary fatty acid (FA) profile by partial replacement of fish oil (FO) with vegetable oils on growth, FA and body composition of juvenile pike perch. An extruded basal diet containing 59 g kg,1 crude lipids (FO) was added with 60 g kg,1 FO, 60 g kg,1 linseed oil (LO) or 60 g kg,1 soybean oil (SO). The resulting dietary FA composition differed mainly in the triglyceride fraction and was characterized by highest amounts of linolenic acid (18:3 n-3) in the LO diet and linoleic acid in the SO diet. Diet enriched with FO contained highest contents of highly unsaturated FA 20:5 n-3 (eicosapentaenic acid) and 22:6 n-3 (docosahexaenic acid). Pike perch were held in a recirculation system and each feeding group (in triplicate) was fed with experimental diets at a daily rate of 35 g kg,1 of biomass for 57 days by automatic feeders. Weight gain and specific growth rate of experimental feeding groups ranged between 18.47 and 19.58 g and 1.37,1.45% day,1 and was not affected by the dietary composition indicating that FO can be replaced by vegetable oils without negative impact on growth performance. In contrast to the whole body and muscle composition, liver tissue was affected by the varying diets. Liver tissues of fish fed diets enriched with vegetable oils showed significantly increased lipid contents of 162 (LO) and 147 (SO) g kg,1 and indicate decreased lipid utilization compared with fish fed FO diet (liver lipid content 112 g kg,1). Nevertheless, hepatosomatic index of pike perch was not influenced by dietary lipid composition. The FA profile of pike perch was generally determined by the dietary FAs. [source] Effects of photoperiod on growth and spawning efficiency of Nile tilapia (Oreochromis niloticus L.) broodstock in a recycling systemAQUACULTURE RESEARCH, Issue 12 2007Abdel-Fattah M El-Sayed Abstract This study was conducted to evaluate the effects of photoperiod on the growth, feed conversion ratio (FCR) and spawning performance of Nile tilapia (Oreochromis niloticus) broodstock. Duplicate groups of two males (66±3.04 g) and six females (50.5±1.58 g) were stocked in 0.4 m3 fibreglass tanks in a recirculating water system at a male:female ratio of 1:3. The fish were subjected to four photoperiod treatments: 24:0 light:dark (L:D), 18L:6D, 12L:12D and 6L:18D. Light intensity was kept constant at about 2500 lx throughout the study. The fish were fed a commercial tilapia diet (35% crude protein and 16.6 MJ GE kg,1) at a daily rate of 2,3% of tank biomass, twice a day, for 130 days. Males grew significantly faster than females under all photoperiod regimes. The best growth rate and FCR were attained at 18L:6D, followed by 24L:0D, 12L:12D and 6L:18D respectively. The number of eggs per female, number of eggs per spawn and number of spawnings per female were all significantly higher in the 12L:12D treatment than in all other photoperiod cycles. Interspawning intervals and days elapsed per spawn were also shorter in the 12L:12D treatment. The time to first spawning was slightly longer in the 24L:0D and 6L:18D than in 12L:12D and 18L:6D light phases. The 18L:6D and 6L:18D photoperiods produced the lowest spawning performance. It is concluded that a 12L:12D photoperiod regime should be adopted for maximum fecundity, seed production and spawning frequencies of Nile tilapia broodstock reared in intensive, recirculating systems. If maximum reproduction is desired, a near-natural day length photoperiod should be used. [source] Comparison of energy and exergy efficiencies of an underground solar thermal storage systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2004H. Hüseyin Öztürk Abstract In this experimental study, solar energy was stored daily using the volcanic material with the sensible heat technique. The external heat collection unit consisted of 27 m2 of south-facing solar air collectors mounted at a 55° tilt angle. The dimensions of the packed-bed heat storage unit were 6 × 2 × 0.6 m deep. The packed-bed heat storage unit was built under the soil. The heat storage unit was filled with 6480 kg of volcanic material. Energy and exergy analyses were applied in order to evaluate the system efficiency. During the charging periods, the average daily rates of thermal energy and exergy stored in the heat storage unit were 1242 and 36.33 W, respectively. Since the rate of exergy depends on the temperature of the heat transfer fluid and surrounding, the rate of exergy increased as the difference between the inlet and outlet temperatures of the heat transfer fluid increased during the charging periods. It was found that the average daily net energy and exergy efficiencies in the charging periods were 39.7 and 2.03%, respectively. The average daily net energy efficiency of the heat storage system remained nearly constant during the charging periods. The maximum energy and exergy efficiencies of the heat storage system were 52.9 and 4.9%, respectively. Copyright © 2004 John Wiley & Sons, Ltd. [source] How costly is clutch formation in the Audouin's Gull Larus audouinii?JOURNAL OF AVIAN BIOLOGY, Issue 4 2000Xavier Ruiz During the Audouin's Gull's breeding season at the Ebro Delta in 1993, 24 fresh eggs from eight three-egg clutches (modal clutch-size) were collected at the peak of the laying period. Eggs were processed to obtain formalin-fixed yolks, which were halved and stained using the potassium dichromate method. Digitized images of the yolks were examined to assess the daily rates of yolk deposition. We used these data in combination with egg compositional analysis to build a model of energy demands during the formation of an average clutch in Audouin's Gull. To show how the different parameters of clutch formation affect the daily energy investment peak, we performed a simulation analysis in which the rapid yolk development (RYD) period, the follicle triggering interval (FTI), the laying interval (LI) and the albumen synthesis period (ASP) were allowed to vary simultaneously. In our sample, the mean RYD period was seven days with a range from six to eight days. There were no significant differences in yolk volume among eggs in a clutch, but albumen volume was significantly smaller in third eggs. According to our model the albumen synthesis of the a-egg coincides with the energy demand peak for clutch formation. This peak represents an increase by ca. 42% in female energy requirements. Values obtained from the simulation analysis showed that only the ASP of the a-egg and the RYD durations of the second and third follicles produced noticeable reductions in peak energy investment. We predict that in gulls, whose laying intervals seem to be kept constant, significant increases of the durations of the RYD periods of second and third eggs, or even significant reductions of yolk size of these eggs, may operate simultaneously to match the energy demands during clutch formation to the prevailing food conditions. [source] Estimation of soil water content and evapotranspiration from irrigated cropland on the North China PlainJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2008Jie Jiang Abstract For nearly 30 y, cropland on the North China Plain (NCP) has been irrigated primarily by pumping groundwater with no sustainable management strategy. This has caused a continuous decline of the water table. A sustainable groundwater management and irrigation strategy must be established in order to prevent further decline of the water table; to do this, one must quantify soil water content and daily rates of deep percolation and locate evapotranspiration from irrigated cropland. For that purpose, we developed a three-layer soil,water balance (SWB) model based on an approach described by Kendy et al. (2003). In this model, the unsaturated soil zone is divided into three layers: a surface active layer, a middle active soil layer, and a lowest passive soil layer. The middle and the lowest layers dynamically change with the development of crop rooting depth. A simple "tipping bucket" routine and an exponential equation are used to redistribute soil water in the three soil layers. The actual evapotranspiration estimated is partitioned into soil evaporation and crop transpiration using a dual crop coefficient reference approach. At first, the model was calibrated using data obtained from five deficiently irrigated field plots located at an experimental site in the NCP between 1998 and 2003. Then, the model was validated by comparing estimated soil water contents with measured ones at three other plots with nondeficient irrigation. The estimates of actual evapotranspiration were compared with those measured with a large-scale weighing lysimeter (3 m2). The index of agreement (IA) for soil water contents varied between 0.62 and 0.80; the concordance correlation coefficient (CCC) and the root mean square error obtained from the same comparison were 0.34,0.65 and 0.043,0.074,cm3,cm,3, respectively. The rates of 10 d mean evapotranspiration estimated by the model show a good fit to those measured by the large-scale lysimeter; this is indicated by IA = 0.94 and CCC = 0.88. Our results indicate that at the irrigated cropland on the plain, deep soil water,percolation rates are usually <200,mm y,1 under nondeficient-irrigation conditions. [source] A full-factor multivariate GARCH modelTHE ECONOMETRICS JOURNAL, Issue 2 2003I. D. Vrontos A new multivariate time series model with time varying conditional variances and covariances is presented and analysed. A complete analysis of the proposed model is presented consisting of parameter estimation, model selection and volatility prediction. Classical and Bayesian techniques are used for the estimation of the model parameters. It turns out that the construction of our proposed model allows easy maximum likelihood estimation and construction of well-mixing Markov chain Monte Carlo (MCMC) algorithms. Bayesian model selection is addressed using MCMC model composition. The problem of accounting for model uncertainty is considered using Bayesian model averaging. We provide implementation details and illustrations using daily rates of return on eight stocks of the US market. [source] | |||||||||||||