Effects of Prey Abundance on the Development of the Spider Agelenopsis potteri (Blackwall) (Araneae: Agelenidae)

1965 ◽  
Vol 97 (2) ◽  
pp. 141-147 ◽  
Author(s):  
A. L. Turnbull
Keyword(s):  
Aedes Aegypti ◽  
Feeding Rate ◽  
Prey Capture ◽  
Prey Abundance ◽  
Feeding Rates ◽  
Live Prey ◽  
Straight Line ◽  
Line Relationship

AbstractAgelenopsis potteri (Blackwall) spiders that were reared from egg to adult on live prey (Aedes aegypti L.) supplied at different daily rates varied in the rate that they were able to capture prey, grow, and attain maturity. Mortality varied inversely with feeding rates, but some spiders matured at each feeding rate. All spiders matured in seven stages regardless of the rate of feeding. Both sexes were mature following the sixth moult. The rate of prey capture declined sharply in the adults. Males matured about four days sooner than females. A straight-line relationship exists between the rate at which prey were captured and the dry weights of the adult spiders. A straight-line relationship was also found between the numbers of prey captured per day and the daily development of the spider.

Differential effects of turbidity on prey consumption of piscivorous and planktivorous fish

2003 ◽  
Vol 60 (12) ◽  
pp. 1517-1526 ◽  
Author(s):  
Alex De Robertis ◽  
Clifford H Ryer ◽  
Adriana Veloza ◽  
Richard D Brodeur
Keyword(s):  
Light Intensity ◽  
Prey Capture ◽  
High Light Intensity ◽  
Prey Consumption ◽  
Planktivorous Fish ◽  
Oncorhynchus Keta ◽  
Feeding Rates ◽  
Anoplopoma Fimbria ◽  
Piscivorous Fish ◽  
Feeding Experiments

Contrast degradation theory predicts that increased turbidity decreases the visibility of objects that are visible at longer distances more than that of objects that are visible at short distances. Consequently, turbidity should disproportionately decrease feeding rates by piscivorous fish, which feed on larger and more visible prey than particle-feeding planktivorous fish. We tested this prediction in a series of laboratory feeding experiments, the results of which indicated that prey consumption by two species of planktivorous fish (juvenile chum salmon (Oncorhynchus keta) and walleye pollock (Theragra chalcogramma)) is much less sensitive to elevated turbidity than piscivorous feeding by sablefish (Anoplopoma fimbria). Planktivorous feeding in the turbidity range tested (0–40 nephelometric turbidity units (NTU)) was reduced at high light intensity, but not at low light intensity. Comparatively low (5–10 NTU) turbidity decreased both the rate at which sablefish pursued prey and the probability of successful prey capture. These results suggest that turbid environments may be advantageous for planktivorous fish because they will be less vulnerable to predation by piscivores, but will not experience a substantial decrease in their ability to capture zooplankton prey.

A Method for Bromine Determination in Wool Fabric by X-Ray Fluorescence Spectrometry

1976 ◽  
Vol 46 (6) ◽  
pp. 463-465 ◽  
Author(s):  
F. William Reuter ◽  
Geraldine E. Secor ◽  
Mendel Friedman
Keyword(s):  
Fluorescence Spectrometry ◽  
Wool Fabric ◽  
X Ray ◽  
Fluorescence Measurements ◽  
Straight Line ◽  
Bromine Concentration ◽  
Wet Chemical ◽  
Relationship Of ◽  
Line Relationship ◽  
Better Than

Bromine is measured in flame-resistant wool fabric by x-ray fluorescence spectrometry with a relative precision of 3 to 8% and relative accuracy of better than 10%. The method computes the bromine concentration from fluorescence measurements of the sample, and a thin film standard, and two measurements of attenuation by the sample. Deviations of 10 to 20% from a straight-line relationship of x-ray counts to bromine concentration are accounted for. X-ray fluorescence is generally useful for routine analyses of bromine in textiles and has advantages over wet chemical analysis.

Comparative Field Energetics of Two Macropod Marsupials and a Ruminant.

1990 ◽  
Vol 17 (6) ◽  
pp. 591 ◽  
Author(s):  
KA Nagy ◽  
GD Sanson ◽  
NK Jacobsen
Keyword(s):  
Feeding Rate ◽  
Energy Content ◽  
Metabolizable Energy ◽  
Ecological Modelling ◽  
Feeding Rates ◽  
Doubly Labelled Water ◽  
Water Influx ◽  
Scaling Relationship ◽  
Field Metabolic Rates ◽  
Free Ranging

Field metabolic rates (FMRs) and water influx rates were measured via the doubly labelled water method in wild Tasmanian pademelons and grey kangaroos living in the Jock Marshall Reserve at Clayton, Victoria, and in wild black-tailed deer free-ranging within a nature reserve at Davis, California. Deer expended more than 3 times more energy per day than similar sized grey kangaroos. Feeding rates required to achieve energy balance were estimated from FMRs along with an estimate of metabolizable energy content of the food. The estimated feeding rates for pademelons and kangaroos were combined with similar values for 5 other species of macropods to calculate an allometric (scaling) relationship for food requirements of macropod marsupials. Feeding rate had the following relationship to body mass: g food (DM) consumed per day = 0.20 g body mass0.79 (r2 = 0.94). The findings reported herein should be useful for predicting the approximate food requirements of free-ranging macropods and deer for purposes of ecological modelling, conservation efforts and management programmes.

Impacts of water temperature on the physiology and behaviours of the sea urchins Heliocidaris crassispina and Mesocentrotus nudus that reflect their range extension and disappearance in the Oga Peninsula, northern Honshu, Japan

2020 ◽  
Author(s):  
Wenping Feng ◽  
Nobuyasu Nakabayashi ◽  
Eri Inomata ◽  
Masakazu N. Aoki ◽  
Yukio Agatsuma
Keyword(s):  
Low Temperature ◽  
Native Species ◽  
Feeding Rate ◽  
Sea Urchins ◽  
Temperature Limit ◽  
Feeding Rates ◽  
Righting Response ◽  
Mesocentrotus Nudus ◽  
Temperature Rate ◽  
High Or Low Temperature

Ocean warming has facilitated the extension of Heliocidaris crassispina to Oga Peninsula, Japan, where the native species Mesocentrotus nudus has disappeared. To verify the temperature impacts on the physiology and behaviour of the two species, we reared small sea urchins at the increasing/decreasing temperature rate of 2.5°C week-1. The righting response, lantern reflex, gonad and gut carbon (C) and nitrogen (N) contents, and feeding rate were investigated. The high and low temperature limits of H. crassispina were 33.3°C and 3.9°C, respectively, which were higher than those of M. nudus. The optimal temperature ranges for behaviour and feeding in H. crassispina were 10.3–31.0°C and 10.3–33.4°C, respectively, which were higher than those in M. nudus. Feeding rates decreased significantly in both species when the temperature approached the high or low temperature limit, but the gut C and N contents of were not greatly affected. At 26–31°C, the feeding rate significantly decreased in M. nudus but not in H. crassispina, which may explain the replacement of M. nudus by H. crassispina in the Oga Peninsula.

The determination of burning velocities of slow flames

1955 ◽  
Vol 228 (1174) ◽  
pp. 297-322 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Burning Velocity ◽  
Flame Temperature ◽  
Excess Energy ◽  
Flat Flame ◽  
Straight Line ◽  
Flame Burner ◽  
Line Relationship ◽  
Propane Butane

Measurements of the burning velocities of methane, ethane, propane, butane, ethylene, carbon monoxide and cyanogen mixtures with air, in the range about 4 to 8 cm, are made by the flat-flame burner method with an accuracy of 2 to 3%. The results can be represented by a straight-line relationship between composition and burning velocity except for carbon monoxide which is sensitive to the percentage of water vapour present. Extrapolated values agree well with recent measurements of faster flames. Measurements are also made on binary mixtures with air of the gases, including hydrogen. The mixture law holds except with mixtures containing carbon monoxide. Limits of inflammability are also determined and the burning velocities at the limits average 3⋅6 cm/s. The mixtures obey the Le Chatelier rule accurately, except for carbon monoxide mixtures. The burning velocities of the hydrocarbons can be represented approximately by a straight-line relationship with the heat generated and with the maximum flame temperature, but correlation is best when thermal conductivity is introduced. At a given velocity the excess energy maintained by the flame appears to be constant for all the hydrocarbons investigated, except methane, which behaves slightly differently. The burning velocities of the hydrocarbons are controlled by a reaction which provides reasonable values of the activation energies and probably precedes the sudden development of chain branching.

TiC Reinforced Steel Matrix Composite Layers Produced by Laser Surface Alloying

2008 ◽  
Vol 59 ◽  
pp. 55-61 ◽  
Author(s):  
A. Fernández-Vicente ◽  
G. Castro ◽  
J.L. Arias ◽  
Maria Angeles Montealegre
Keyword(s):  
Wear Resistance ◽  
Feeding Rate ◽  
Laser Surface ◽  
Beam Power ◽  
Powder Injection ◽  
Steel Matrix ◽  
Surface Alloying ◽  
Feeding Rates ◽  
Laser Surface Alloying ◽  
Powder Feeding

In the present work, laser surface alloying of H13 tool steel by using TiC has been performed by means of DHPDL (Direct high power diode laser). Different layers were produced by varying laser beam power and powder feeding rate. Several alloying degrees were obtained depending on the laser parameters employed. Laser surface alloyed layers were analyzed by using optical and scanning electron microscopy. Wear resistance was evaluated through pin-on-disk tests at room temperature. In general, it was observed that dilution of TiC powders into the molten H13 substrate decreased as the powder-feeding rate increased and particles size of the titanium carbide precipitates was larger for the higher feeding rates. Wear measurements showed lower values for the wear resistance coefficient of laser alloying layers produced at higher values of the powder injection (feeding) rate. Analysis of the wear surface track was conducted and the specific contribution of the microstructural features on the wear coefficient was assessed. Thus, it was found that larger particles sizes and particle contents protected the martensitic and dendritic steel matrix from being deeply worn. Lower TiC contents in the alloyed layer gave rise to a higher contribution of the plastic deformation in the wear track.

A Conceptual Model for the Estimation of the Sensitivity of Black Fly Larvae to Bacillus thuringiensis var. israelensis

1989 ◽  
Vol 46 (10) ◽  
pp. 1785-1792 ◽  
Author(s):  
Antoine Morin ◽  
Christian Back ◽  
Jacques Boisvert ◽  
Robert H. Peters
Keyword(s):  
Bacillus Thuringiensis ◽  
Feeding Rate ◽  
Standard Procedure ◽  
Dry Mass ◽  
Published Data ◽  
Contact Period ◽  
Larval Feeding ◽  
Feeding Rates ◽  
Black Fly ◽  
Proposed Model

Results from bioassays of a commercial formulation of Bacillus thuringiensis var. israelensis (Teknar HP-D) are combined with an empirical model of the feeding rate of larvae of a target species of black fly (Simulium venustum/verecundum) to develop a model relating the mortality of larvae to the amount of formulation ingested per unit mass of larvae (specific ingested dose). LD50 of Teknar HP-D was about 1 μg wet mass of Teknar per milligram dry mass of larvae, and independent of size of the larvae and seston concentration. Compared with standard assay analysis relating the mortality to the dose (milligrams per litre times seconds), the proposed model allowed more precise and replicable estimation of the effective dose. Reanalysis of published data on the potency of another Bti formulation (Teknar WDC), confirmed the superiority of the proposed model over the standard procedure. Susceptibility of larvae to particulate larvicides is mainly a function of the larval feeding rate. In addition to size of the larvae, temperature, and seston concentration, analysis of the model reveals that the length of the contact period and the variability of feeding rates among individual larvae are important factors determining the mortality rate following treatments.

Comparative Agonistic and Feeding Behavior of Hatchery-Reared and Wild Salmon in Aquaria

1968 ◽  
Vol 25 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Owen C. Fenderson ◽  
W. Harry Everhart ◽  
Kenneth M. Muth
Keyword(s):  
Social Interaction ◽  
Atlantic Salmon ◽  
Feeding Behavior ◽  
Salmo Salar ◽  
Social Dominance ◽  
Food Preference ◽  
Feeding Rate ◽  
Feeding Time ◽  
Feeding Rates ◽  
Wild Salmon

When hatchery-reared and wild landlocked Atlantic salmon (Salmo salar) parr of the same age and size were permitted to compete for social dominance and for food in aquaria, twice as many hatchery salmon attained dominance as wild salmon. Dominant hatchery salmon also showed a higher intensity of aggressiveness than dominant wild salmon, displaying a higher and more variable mean nipping rate. Socially dominant salmon ate more food per fish than subordinates, but there were no statistically significant differences in feeding rate between dominant hatchery and dominant wild salmon, or between subordinate hatchery and subordinate wild salmon.Hatchery salmon displayed lower feeding rates than wild salmon when they were held in separate compartments of an aquarium and compared at three temperatures. This difference in feeding rate probably was not a reflection of differences in adaptation to temperature or food preference, but, rather, was the result of interference with feeding caused by the more intense social interaction among hatchery fish.It is suggested that high levels of aggressiveness may contribute to mortalities of hatchery-reared salmon planted in streams because of loss of feeding time, excessive use of energy, and increased exposure to predators.

Age, Sex and Prior Site Experience Have Independent Effects On the Foraging Success of Wintering Snow Buntings

Behaviour ◽  
1994 ◽  
Vol 129 (1-2) ◽  
pp. 99-111 ◽  
Author(s):  
Richard D. Smith ◽  
Neil B. Metcalfe
Keyword(s):  
Competitive Ability ◽  
Feeding Rate ◽  
Prior Experience ◽  
Residual Effects ◽  
Flock Size ◽  
Foraging Success ◽  
Feeding Rates ◽  
North East ◽  
Independent Effects ◽  
Feeding Bout

AbstractIntraspecific variation in foraging success amongst birds is often associated with differences between individuals in competitive ability or experience. However, it is usually difficult to separate the importance of experience per se from that of age. Here we examined the feeding rates of wintering snow buntings (Plectrophenax nivalis) at Cairn Gorm, North-east Scotland in both competitive and non-competitive situations. Although flock-size/density and stage of the feeding bout accounted for most of the explainable variation in peck-rates, there remained significant and additive residual effects of both age and prior experience of the site (older/more experienced birds achieving higher feeding rates) and these effects were very similar for birds feeding alone or in flocks. Sex differences in feeding rates were only apparent in large flocks, where males (the dominant sex) had faster peck-rates than females. Birds without previous experience (whether age or site-related) showed increases in relative feeding rate during the course of the winter, whereas experienced birds did not. This suggests that the differences between experienced and inexperienced birds were due to learning rather than the disproportionate loss of poor foragers.

Comparative studies of meat V. Factors affecting the iodine number of the fat from the fatty and muscular tissues of cattle

1956 ◽  
Vol 48 (1) ◽  
pp. 61-73 ◽  
Author(s):  
E. H. Callow ◽  
S. R. Searle
Keyword(s):  
Iodine Number ◽  
Comparative Studies ◽  
Analysis Of Covariance ◽  
Muscular Tissue ◽  
Fatty Tissue ◽  
Factors Affecting ◽  
Rectangular Hyperbola ◽  
Straight Line ◽  
Line Relationship ◽  
Muscular Tissues

1. Carcasses of twenty-one fat cattle (from six cows, ten steers and five heifers, aged from 12 months to 12 years and representing seven breeds) have been dissected into nine joints, and the fatty and muscular tissue from each joint dissected and analysed for fat. The iodine number of each sample of fat has been determined.2. The fat in fatty tissues ranged from 28·3 to 96·7%, and in muscular tissues from 1·3 to 14·2%. Iodine numbers of fat from fatty tissues ranged from 34·0 to 69·0 and those of fat from muscular tissues from 45·9 to 73·2.3. By an analysis of covariance it has been possible to reduce these data to two families of regression lines—those for fatty tissue and those for muscular tissue.4. The equations for fatty tissue have the following generalized form:I.N. = AFT + CFT + JFT + b1F/FT,where AFT = 55·6 ± 1·7 and is a general constant,CFT is a series of constants for the various carcasses and ranges from +12·6 to −6·7,JFT is a series of constants for the various joints and ranges from +6·6 to −10·3,b1 is a general constant with the value −0·052(± 0·025),F/FT is the percentage of fat in any given sample of fatty tissue, and I.N. is its iodine number.5. A similar set of equations has been deduced for muscular tissue. Here, however, the relation between iodine number and percentage of fat is a rectangular hyperbola. Consequently, the inverse (Z) of the percentage of fat (in order to get a straight-line relationship) has been used.

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