bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Dietary Reference Intakes in dietary assessment and planning
Authors: Barr Susan I
Published: March 2006

Dietary Reference Intakes (DRIs) are used for assessing and planning diets of individuals and groups. Assessing individual intakes is complicated by the fact that neither the individual's usual nutrient intake nor their individual requirement is known. However, the degree of confidence that intakes are adequate or excessive can be estimated. Assessing diets of groups requires information on the group's usual nutrient intake distribution, which can be obtained by statistically adjusting 1 d intake distributions to remove within-person variability. For most nutrients with an Estimated Average Requirement (EAR), the group prevalence of inadequate intakes can be approximated by the percent whose usual intakes are less than the EAR. However, the prevalence of inadequacy cannot be determined for nutrients with an Adequate Intake (AI). The goals of planning are a low risk (for individuals) or low prevalence (for groups) of inadequate or excessive nutrient intakes. For individuals, these goals are met by planning intakes that meet the Recommended Dietary Allowance (RDA) or AI, are below the Tolerable Upper Intake Level (UL), and fall within the Acceptable Macronutrient Distribution Ranges (AMDRs). For groups, planning involves estimating a "target" usual intake distribution with an acceptably low prevalence less than the EAR and greater than the UL, planning menus to achieve the target distribution, and assessing the results.Key words: nutrition assessment, dietary planning, nutrient adequacy.
Dietary Reference Intakes for the micronutrients: considerations for physical activity
Authors: Whiting Susan J , Barabash Wade A
Published: March 2006

The Dietary Reference Intakes (DRIs) are a set of recommendations for healthy persons. For the most part, recommendations are determined experimentally under controlled conditions of light activity. During increased physical activity, it is expected that micronutrient requirements would increase relative to the inactive state. Micronutrients of interest to athletes are those associated with oxygen handling and delivery, such as iron, and vitamin D, a newly emerging function of which is to maintain muscle strength. The DRI report on electrolytes (including water) is the most recent set of recommendations. In addition to recommendations for intakes to meet needs, many micronutrients have an upper level that indicates caution in consuming a large amount. We illustrate the process of setting DRI values for the micronutrients (including electrolytes and water), and provide a summary of instances where physical activity needs were considered when DRI values were derived. Understanding the origin of DRI values for micronutrients will assist in understanding how to use the values in assessment and planning.Key words: iron, vitamin D, electrolytes, physical activity, nutrient reference standards, adverse effects.
Dietary Reference Intakes for the macronutrients and energy: considerations for physical activity
Authors: Zello Gordon A
Published: March 2006

The Dietary Reference Intakes (DRIs) are the North American reference standards for nutrients in the diets of healthy individuals. The macronutrient DRI report includes the standards for energy, fat and fatty acids, carbohydrate and fiber, and protein and amino acids. Equations used to identify the Estimated Energy Requirement (EER) were also developed based on individual characteristics including levels of physical activity. The DRIs for the macronutrients are presented as Recommended Dietary Allowances (RDAs) or Adequate Intakes (AIs), as well as Acceptable Macronutrient Distribution Ranges (AMDRs), and were arrived at by considering both nutrient inadequacies and excesses. In addition, recommendations are made that would reduce the risk of chronic diseases, such as setting intake limits for added sugar; reducing cholesterol, saturated, and trans fatty acids consumption; and increasing levels of physical activity. As healthy individuals include those engaged in various levels of physical activity, the DRIs should apply to the athlete and address their macronutrient and energy needs. This paper summarizes the macronutrient DRI report as applied to the adult, with discussion of the dietary needs of those engaged in various levels of physical activity, including the athlete.Key words: nutrition, requirements, guidelines, performance, human.
Physical activity and the metabolic syndrome in Canada
Authors: Brien Susan E , Katzmarzyk Peter T
Published: March 2006

The metabolic syndrome (MetS) is a cluster of risk factors that predispose individuals to cardiovascular disease. Therapeutic lifestyle changes, including increased physical activity, are recommended for the prevention and treatment of MetS. The purpose of this study was to examine the relationship between physical activity and MetS in Canada. The sample included 6406 men and 6475 women aged 18-64 y who were participants in the Canadian Heart Health Surveys (1986-1992). MetS was classified using criteria modified from the US National Cholesterol Education Program. Participants were deemed physically active if they were active at least once each week for at least 30 min, engaging in strenuous activity some of the time. The relationship between physical activity and MetS was assessed using logistic regression, with age, smoking, alcohol consumption, and income adequacy as covariates. A total of 14.4% of Canadians had MetS and 33.6% were physically active. The odds ratio for MetS was 0.73 (95% confidence interval (CI): 0.54-0.98; p < 0.05) for physically active vs. physically inactive participants. The corresponding odds ratios were 0.45 (95% CI: 0.29-0.69; p < 0.001) and 0.67 (95% CI: 0.44-1.02; p = 0.06) for men and women, respectively. In summary, physical activity was associated with lower odds of MetS, particularly in men. Further research is required to determine the effectiveness of physical activity in the treatment of MetS.Key words: metabolic syndrome, physical activity, Canadian Heart Health Surveys.
Nutrition for healthy pregnancy outcomes
Authors: Vause Tannys , Martz Pat , Richard Francesca , Gramlich Leah
Published: March 2006

Many healthcare professionals and their patients are aware of the importance of proper nutrition during pregnancy, but may not be aware of specific nutritional recommendations on how to achieve a healthy pregnancy outcome. This review article aims to discuss the implications maternal nutritional status and weight gain have in both the short and long terms. Babies born to mothers with inadequate weight gain are more likely to be premature and small for gestational age (SGA). They are also predisposed to obesity and metabolic problems later in life. Women with excessive weight gain during pregnancy are at increased risk for developing type II diabetes later in life. Their offspring also have increased body fat as babies and during childhood. Pregnant women need to be informed about appropriate weight gain and how to achieve this, and should be given specific nutritional recommendations and weight-gain goals.Key words: nutritional requirements, healthy eating, weight gain, weight retention, obesity, birth weight.
Symposium overview. Dietary Reference Intakes: considerations for physical activity
Authors: Whiting Susan J
Published: March 2006

The following series of papers comprise a symposium on Dietary Reference Intakes (DRIs), which are the new dietary recommendations for North Americans, that was presented at the 2004 Annual Meeting of the Canadian Society for Exercise Physiology. The process of developing the DRIs has been an enormous undertaking resulting, thus far, in 12 book-length reports spanning from 1997 to 2004. It was therefore timely to review the recommendations, describe the considerations for physical activity that went into setting the recommendations, and, where possible, indicate how the DRIs may be applied to athletes.Key words: Dietary Reference Intakes, macronutrients, micronutrients, physical activity.
Effect of coarse aggregate size on strength and workability of concrete
Authors: Tumidajski Peter J , Gong B
Published: March 2006

The properties of concrete were studied when the proportions of 37.5 and 19.5 mm stone in the coarse aggregate were varied. With the cement content of 160 kg/m3 and the ratio of water/cement (w/c) greater than 0.9, the compressive strength is maximum at 25 percent by weight (w/o) of 37.5 mm stone. Conversely, for the cement content of 350 kg/m3 and w/c ratios of less than 0.50, maximum compressive strength is substantively reduced. For both 160 kg/m3 and 350 kg/m3 cement contents, workability improves slightly as the proportion of the 37.5 mm stone is increased. For 100 mm fixed slumps and cement content of less than 160 kg/m3, there was little change in compressive strength as the proportion of 37.5 mm stone increased. However, when cement content was increased from 190 to 350 kg/m3, maximum compressive strength was observed, which shifted downward from 50 w/o to 25 w/o of 37.5 mm stone. In general, to maintain a 100 mm slump, water demand decreased as the proportion of 37.5 mm stone in the coarse aggregate fraction increased.Key words: concrete, compressive strength, workability, slump, aggregate, size, cement.
Bond strength of concrete plugs embedded in tubular steel piles under cyclic loading
Authors: Nezamian Abolghasem , Al-Mahaidi Riadh , Grundy Paul
Published: March 2006

Investigation of the load transfer of concrete plugs to tubular steel piles subjected to tension and compression and cyclic loading has been conducted at Monash University over the past 3 years. The work presented in this paper reports on the results of the combination of pull-out, push-out, and cyclic loading tests carried out on 15 steel tube specimens filled partially with reinforced concrete with variable lengths of embedment. The pull-out force was applied through steel reinforcing bars embedded in the concrete plug, and push-out forces were applied through a thick top circular plate on the top of the concrete plug. Test results included the cyclic loading, ultimate pull-out and push-out forces, slip of concrete plugs, and longitudinal and hoop strains along the piles for some specimens. The tests clearly showed that average bond strength significantly exceeds expectations and is higher than the results of previous investigations using plugs without reinforcement. The test results also indicated that cyclic loading tests reduced the bond strength due to the accumulation of damage to the plug–pile interface. The push-out and pull-out tests conducted under symmetric cyclic loading demonstrated that slip between the concrete plug and the steel tube increased with repeated loading, and the rate of slip growth increased with an increase in the peak load.Key words: tubular steel pile, reinforced concrete plug, bond, cyclic loading.
Structural design properties of concrete for a bridge in Alberta
Authors: Soleymani Hamid R
Published: March 2006

In this investigation, the structural design properties of concrete were characterized. Compressive, tensile, and flexural strengths were measured at different ages. In addition, modulus of elasticity, Poisson's ratio, creep, shrinkage, and various other properties were measured. Laboratory results were compared with several structural codes used by engineers for bridge and structural design. The results serve as a reminder that assumed code values can be significantly in error and must be used only in the absence of better data.Key words: concrete, creep, shrinkage, modulus of elasticity, strength, design.
Development of fiber reinforced concrete repair materials
Authors: Banthia N , Gupta R , Mindess S
Published: March 2006

Early age shrinkage cracking remains a critical concern for cement-based repairs and overlays. Fibers mitigate such cracking, but no standardized technique of assessing the performance of a given fiber exists. Recently, a novel technique of making such an assessment was developed at The University of British Columbia (UBC). In this test method, currently being balloted through the ASTM, an overlay of fiber reinforced concrete (FRC) material to be tested is cast directly on a fully matured sub-base with protuberances, and the entire assembly is subjected to controlled drying. Cracking in the overlay is then monitored and characterized. The technique was recently employed to develop "crack-free" overlay materials for two repair sites. One was a parking garage in Downtown Vancouver, British Columbia, and the other was the plaza deck at The UBC Aquatic Center. For the parking garage, a carbon fiber reinforced concrete and for the plaza deck, a cellulose fiber reinforced concrete were developed. Both overlays were instrumented with strain sensors and data were monitored over the Internet.Key words: fiber reinforced concrete, shrinkage cracking, strain monitoring, carbon fibers, cellulose fibers.
Observations of riverbed scour under a developing hanging ice dam
Authors: Sui Jueyi , Hicks Faye E , Menounos Brian
Published: March 2006

This paper illustrates the importance of river ice accumulations in changing river channel geometry based on field investigations carried out at the Hequ gauging station on the Yellow River in China. A relationship is established between riverbed deformation and ice accumulation.Key words: river ice, hanging dam, ice accumulation, river scour, Yellow River.
Comparative study of performance of natural fibres and crumb rubber modified stone matrix asphalt mixtures
Authors: Sharma Vikas , Goyal Shweta
Published: March 2006

Stone matrix asphalt (SMA) is a gap-graded mix that contains a high concentration of coarse aggregate, thereby maximizing stone-to-stone contact in the mixture and providing an efficient network for load distribution. Coarse aggregate particles are held together by a rich matrix of mineral filler and stabilizer in the thick asphalt film. This paper presents details on the laboratory studies carried out on stone matrix asphalt (SMA) mixtures with natural fibres and crumb rubber modified bitumen (CRMB). Indirect tensile strength, retained stability, resistance to moisture susceptibility, resistance to rutting, resistance to creep, and resistance to permeability and aging were found to improve with SMA mixtures with CRMB when compared with SMA mixtures with fibres as stabilizers.Key words: natural fibres, CRMB, SMA mixtures, draindown, moisture damage, creep, rutting, permeability, aging.
Pier scour and thin layered bed scour within a long contraction
Authors: Raikar Rajkumar V , Dey Subhasish
Published: March 2006

The paper presents an experimental investigation of (i) scour at a pier within a long contraction and (ii) scour of a thin layered bed within a long contraction. The scour depth at piers within long contractions increases with an increase in sediment size and a decrease in channel opening ratio. A theoretical calculation proposed to estimate the maximum equilibrium scour depth suggests that it is the summation of the individual equilibrium scour depth within a long contraction and the equilibrium scour depth at a pier under critical flow conditions in the upstream bed. The scour depth (relative to the approaching flow depth) within long contractions with thin gravel layers increases with an increase in the ratio of the diameter of the surface gravel to that of the bed sand and a decrease in the channel opening ratio. The scour depth within a channel contraction with a gravel layer, however, is greater than that with a unlayered bed of uniform sediment. Further, the maximum equilibrium scour depths within long contractions with gravel layers calculated theoretically using the energy and continuity equations are in agreement with the experimental data.Key words: bridge pier, contraction, scour, erosion, sediment transport, open-channel flow, hydraulic engineering.
Development of an equation for aluminum alloys to determine the width of the zone affected by welding
Authors: Aleo V , Madugula M K.S , Balachandar R
Published: March 2006

Canadian Standards Association standard CAN3-S157-M83 (R2002), Strength design in aluminum, requires that the zone affected by welding be taken to extend a distance of 25 mm each side from the centre of the weld. The objective of this investigation was to develop an equation to determine the width of the zone affected by welding adjacent to a weld for a given set of parameters. One hundred and twelve weldment specimens were fabricated using five alloys, seven material thicknesses, and different heat fluxes. Hardness was measured in the zone affected by welding to determine the width and hardness gradient. The investigation has determined that the width of the zone affected by welding depends on several parameters. The heat flux has the greatest influence on the width of the zone affected by welding. Factors such as plate thickness, thermal conductivity, and multipass welding also have an effect on the width of the zone affected by welding. It is concluded based on this investigation that the width of the zone affected by welding can be reduced substantially in welded connections fabricated using properly selected weldable aluminum alloys and thicknesses and an automatic process mode with a low and uniform heat flux.Key words: aluminum alloys, hardness, heat flux, welding.
Reinforced concrete beams without stirrups considering shear friction and fracture mechanics
Authors: Kazemi M T , Broujerdian V
Published: March 2006

A new expression for the shear capacity of reinforced concrete beams without stirrups was derived by calculating the aggregate interlock capacity across the major diagonal crack of the beam, a procedure somewhat similar to those based on the modified compression field theory. Two formulas were obtained from the simplification of this expression. All three relations capture the dependence of shear strength on the size of the beam, the ratio of shear span to beam depth, longitudinal reinforcement ratio, maximum aggregate size, and concrete strength. The limits of these formulas agree well with the limit solutions of shear failure load for very small and very large beams based on plastic and fracture mechanics solutions, respectively. The proposed relations were calibrated by least-squares fitting of the existing experimental database (consisting of 398 data points) and resulted in low coefficients of variation. The simplest version is suitable for design codes.Key words: reinforced concrete, shear strength, beams, aggregate interlock, crack opening, size effect.
Comparison of frequency- and time-domain analyses for guyed masts in turbulent winds
Authors: Sparling B F , Wegner L D
Published: March 2006

Both frequency- and time-domain methods have been employed in the dynamic analysis of guyed telecommunication masts subjected to turbulent winds. Although the probabilistic frequency-domain approach offers some advantages in terms of its relative ease of implementation and in the statistical reliability of wind load descriptions, the deterministic time-domain method permits a more realistic treatment of system nonlinearities. In this study, a numerical investigation was undertaken to compare frequency- and time-domain dynamic response predictions for a selected guyed mast in gusty winds. Two different analysis techniques were employed, with the frequency-domain calculations performed using response influence lines and the time-domain analyses carried out using a stiffness-based finite element model. Good agreement was observed in root-mean-square and peak dynamic response estimates after compensation was included for differences in turbulence intensity levels assumed in the two models. In general, natural frequencies and mode shapes were also similar.Key words: guyed mast, dynamic analysis, wind, turbulence, nonlinear behaviour, finite element analysis, cables, frequency domain, time domain.
Seismic testing and performance of buckling-restrained bracing systems
Authors: Tremblay R , Bolduc P , Neville R , DeVall R
Published: March 2006

This paper describes a subassemblage seismic test program performed on six buckling-restrained braces (BRBs). Two different brace core segment lengths and two different buckling-restraining mechanisms were examined. The applied loading histories included a qualifying quasi-static cyclic test with stepwise incremental displacement amplitudes and a dynamically applied seismic loading. A test was also carried out on a conventional bracing member for comparison purposes. The concrete-filled tube specimens exhibited satisfactory performance under the quasi-static loading protocol, regardless of the length of the core segment. Strain hardening and frictional responses resulted in brace axial forces significantly exceeding the core yield capacity. The steel BRB system exhibited good performance under the quasi-static and dynamic loading sequences, provided that the clearance between the brace core and the buckling-restrained mechanism was kept to a minimum. The dynamic loading protocol was less severe for low-cycle fatigue than the quasi-static loading, but higher strain rates resulted in amplified yield resistance. The conventional bracing member withstood the entire quasi-static loading history but exhibited limited energy-dissipation capacity compared with the concrete-filled BRBs.Key words: concentrically braced steel frames, bracing members, buckling, energy dissipation, friction, yielding, fracture, seismic.
Effects of group size on the threat-sensitive response to varying concentrations of chemical alarm cues by juvenile convict cichlids
Authors: Brown Grant E , Bongiorno Tony , DiCapua Daniel M , Ivan Laura I , Roh Ellie
Published: March 2006

The threat-sensitive predator avoidance model predicts that prey should balance the intensity of antipredator responses against perceived predation risk, resulting in a graded response pattern. Recent studies have demonstrated considerable interspecific variation in the intensity of threat-sensitive response patterns, ranging from strongly graded to relatively nongraded or "hypersensitive" threat-sensitive response patterns. Here, we test for intraspecific plasticity in threat-sensitive responses by varying group size. We exposed juvenile convict cichlids, Archocentrus nigrofasciatus (Günther, 1867), as individuals or in small (groups of three) or large (groups of six) shoals to a series of dilutions of conspecific chemical alarm cues and a distilled water control. Singleton cichlids exhibited significant reductions in time spent moving and in frequency of foraging attempts (relative to distilled water controls) when exposed to a 12.5% dilution of conspecific alarm cue, with no difference in response intensity at higher stimulus concentrations, suggesting a nongraded (hypersensitive) response pattern. Small shoals exhibited a similar response pattern, but at a higher response threshold (25% dilution of stock alarm cue solution). Large shoals, however, exhibited a graded response pattern. These results suggest that group size influences the trade-off between predator avoidance and other fitness related activities, resulting in flexible threat-sensitive response patterns.
Suction disk performance of echeneid fishes
Authors: Fulcher B A , Motta P J
Published: March 2006

The anatomy of the suction disk of two species of echeneid fishes, Echeneis naucrates L., 1758 and E. neucratoides Zuiew, 1786, is described, and measurements of their suction performance on both smooth and textured surfaces are given. Disk muscles erect or depress the numerous paired laminae, or toothed plates, which bear two to four rows of posteriorly directed spinules. The erect laminae create a sub-ambient chamber, allowing these fishes to adhere to other fish and inanimate objects. Resting sub-ambient suction pressure differentials were recorded, as were the greatest sub-ambient pressure differentials as the fish were pulled posteriorly to simulate drag induced by a swimming host. The resting pressure differential averaged –0.5 kPa, with no significant difference between Plexiglas®and shark skin surfaces. With a force applied to their caudal peduncle, the echeneids generated suction pressure differentials averaging –92.7 kPa within the disk cavity while attached to Plexiglas. On shark skin, the use of spinules increased friction and reduced the maximum sub-ambient suction pressure differential to –46.6 kPa; considerably more force (17.4 N) was required to dislodge the echeneids from the shark skin than from the smooth Plexiglas (11.2 N).
Body temperature fluctuations in free-ranging eastern foxsnakes (Elaphe gloydi) during cold-water swimming
Authors: MacKinnon Carrie A , Lawson Anna , Stevens E D , Brooks Ronald J
Published: March 2006

We examined the thermal biology of free-ranging terrestrial eastern foxsnakes (Elaphe gloydi Conant, 1940) that were voluntarily swimming in cold water during spring, in Georgian Bay, Ontario, Canada. Using temperature-sensitive radiotelemetry, we recorded body temperatures of foxsnakes during 12 cold-water swims, and subsequent warming on shore. During these swims, water temperatures were from 11 to 22 °C and distances of 85–1330 m were travelled. Snakes that were in cold water long enough equilibrated with water temperature and did not maintain a body temperature above ambient. The largest observed drop in body temperature was 22.6 °C (over 11 min) and the largest increase was 23 °C (over 66 min). Such large, rapid temperature fluctuations have not previously been reported in detail from snakes in the field. Twice as many telemetry observations as expected occurred between 1200 and 1400, suggesting that snakes chose to swim midday. Additionally, our results suggest that foxsnakes bask to raise their body temperature prior to swimming in cold water. We compared swimming speed and the coefficient of temperature change among foxsnakes and other snake species. Swimming speed was positively correlated with water temperature, similar to other findings. We found no clear trend between mass and the coefficients of cooling and warming; however, snakes cooled in water 2.8–8.6 times faster than they warmed in air.
Species richness and biodiversity conservation priorities in British Columbia, Canada
Authors: Freemark Kathryn E , Meyers Mark , White Denis , Warman Leanna D , Kiester A Ross , Lumban-Tobing Pago
Published: March 2006

Patterns in the geographic distribution of seven species groups were used to identify important areas for conservation in British Columbia, Canada. Potential priority sites for conservation were determined using an integer programming algorithm that maximized the number of species represented in the minimum number of sites. Sweep analyses were used to determine how well the set of priority sites identified for each species group represented the other species groups. Although areas of highest species richness were different for each species group, they all included sites in the southern interior of British Columbia, where there is limited protection. Furthermore, less than 13% of the distribution ranges for 23 of 25 bird species of special conservation concern were located within existing protected areas. Species at risk of extinction were poorly represented (26%–42%) in priority sets of sites selected for amphibians, reptiles, birds, and mammals, since these sites were generally scattered throughout the province. However, priority sites for species at risk represented 72%–91% of the species in other groups. Therefore, conservation activities in sites identified for such species have the potential to benefit many other species. These sites could be investigated in more detail to augment existing conservation and protection efforts in British Columbia.
Pathogenicity of the hymenolepidid cestodeMicrosomacanthus hopkinsiin its intermediate host,Hyalella azteca: implications for transmission, host fitness, and host populations
Authors: Kokkotis T , McLaughlin J D
Published: March 2006

Infection by larval parasites can have severe consequences on intermediate hosts that affect transmission, fecundity and fitness of the host, and host population structure. This study examines the pathogenic effects of cysticercoid larvae of the hymenolepidid cestode Microsomacanthus hopkinsi (Schiller, 1951) on its amphipod intermediate host, Hyalella azteca Saussure, 1858. There was a significant, positive relationship between oncosphere consumption, cysticercoid burden, and age in short-term experiments in which groups of H. azteca were exposed individually to single egg packets of M. hopkinsi during instars 1, 2, 3, 4, 6, 8, and 9; however, there was no correlation between oncosphere consumption and the intensity of infection in the amphipod hosts within each instar. The mean number of moults over a 14 day experimental period was significantly less in infected amphipods than in their respective controls. In short-term experiments, the greatest mortality appeared to be limited to amphipods exposed during the earliest instars; little mortality was observed in amphipods exposed during instar 4 or later. Long-term experiments revealed a significant negative effect of infection on the overall life span of both male and female H. azteca exposed individually to a single egg packet during instar 4. Of 72 females infected during instar 4 and provided with mates during instar 6, only 1 and 4 produced broods in instars 8 and 9, respectively, compared with 58 and 57 of 72 control females. Broods produced by infected females were significantly smaller than those of control females. Infected individuals were less likely to mate successfully. The results are discussed in terms of their consequences for transmission, host fitness, and potential effects on host populations.
Antipredator behavior of chytridiomycosis-infected northern leopard frog (Rana pipiens) tadpoles
Authors: Parris Matthew J , Reese Elisheva , Storfer Andrew
Published: March 2006

We investigated the effects of Batrachochytrium dendrobatidis Longcore, Pessier & Nichols, a pathogen implicated in global amphibian population declines, on antipredator behavior of northern leopard frog (Rana pipiens Schreber, 1782) tadpoles in response to visual and chemical cues of a fish predator, bluegill sunfish (Lepomis macrochirus Rafinesque, 1819). We placed infected and uninfected tadpoles in containers partitioned with a transparent divider and measured tadpole activity and distance from the center. Infected tadpoles had significantly lower activity levels across all treatments. When exposed to only visual cues, uninfected tadpoles positioned themselves farther from the center divider (and thus the predator) than infected animals. All tadpoles were at similar distances from the center when exposed to chemical cues only, likely because chemical cues alone do not provide spatial information on the location of predators. Infected tadpoles were significantly farther from the center divider than uninfected ones when exposed to visual and chemical cues together, suggesting that, although the mechanism is unknown, both cues are necessary to stimulate predator avoidance behavior for infected animals. In a second experiment, infected tadpoles experienced lower mortality than uninfected ones in the lethal presence of fish. Thus, effects of infection on behavioral antipredator responses are complex, but lower host susceptibility to predation, low activity, and greater distance from predators when both chemical and visual predator cues are present likely benefits B. dendrobatidis, which relies on host survival for transmission.
Population profile of an introduced species, the common wall lizard (Podarcis muralis), on Vancouver Island, Canada
Authors: Allan G Michael , Prelypchan Christopher J , Gregory Patrick T
Published: March 2006

Introduced species represent one of the greatest potential threats to persistence of native species. Therefore, it is important to understand the ecology of introduced species in order to develop appropriate mitigation strategies if required. In this study, using data collected in 1992–1993, we describe some fundamental population attributes of common wall lizards, Podarcis muralis (Laurenti, 1768), of Italian origin, introduced near Victoria, British Columbia, in the early 1970s. Male and female wall lizards reached similar snout–vent lengths, but males had relatively longer tails and were heavier. However, when gravid, females attained a body mass similar to that of males of equal snout–vent length. We found gravid females in all months from May to July, inclusive, but hatchlings did not appear in the field before late July. Growth rate was inversely related to body size, and lizards probably reached maturity in their second full summer. Larger lizards were more likely than smaller lizards to have experienced tail loss prior to capture, but the probability of tail loss upon capture was higher for smaller lizards than for adults. Our results suggest no fundamental differences in population characteristics between P. muralis on southern Vancouver Island and populations at sites within the species' natural range in Europe. Whether P. muralis on Vancouver Island is a threat to the native northern alligator lizard, Elgaria coerulea (Wiegmann, 1828), remains an open question.
Stealthy slugs and communicating corals: polyp withdrawal by an aggregating soft coral in response to injured neighbors
Authors: Goddard Jeffrey H.R
Published: March 2006

The polyps of Discophyton rudyi (Verseveldt and van Ofwegen, 1992), a small, aggregating, alcyonacean soft coral found on rocky shores in the northeast Pacific Ocean, are selectively preyed on by the nudibranch Tritonia festiva (Stearns, 1873). In the laboratory, D. rudyi retracted their polyps when exposed to water-borne cues from a conspecific colony that was successfully attacked by T. festiva. This same inter-colony response was elicited by attacks simulated with fine scissors, but not by (i) the presence of T. festiva attempting to feed but prevented from damaging its prey, (ii) the simple withdrawal of the soft coral polyps, or (iii) seawater controls. The cue(s) eliciting polyp retraction therefore emanate from the soft coral and not its nudibranch predator. Tritonia festiva often attacks neighboring colonies, which are usually separated by only a few millimetres, in rapid succession but will not attack colonies with retracted polyps. It also cannot move rapidly to reach more distant colonies. Therefore, polyp retraction by one colony in response to predation on a neighboring colony effectively serves as an anti-predatory alarm response. Although aggregations of D. rudyi are largely clonal, the response to water-borne cues from injured conspecifics does not appear to be clone-specific. Few examples of intra-specific alarm responses are known from sessile marine invertebrates, but the similarities between them suggest that other examples may be found in suspension or deposit-feeding taxa that form dense aggregations and are preyed on by stealthy partial-predators likely to attack adjacent individuals or colonies in rapid succession.
Repeatability of cell-mediated and innate immunity, and other fitness-related traits, in the Grey Partridge
Authors: Cucco Marco , Malacarne Giorgio , Ottonelli Roberta , Patrone Mauro
Published: March 2006

Immunocompetence is considered a reliable indicator of general body condition and ultimately of fitness. It has been suggested that, as a parameter subjected to intense directional selection, the level of additive genetic variance expressed should be reduced; on the other hand, theoretical models of host–parasite coevolution assume that variation in parasite resistance has a genetic basis. Contradictory results have been reported in birds, since the heritability of immune responses varies from nil to high. In this study of Grey Partridge (Perdix perdix (L., 1758)), we examined the heritability of immune condition (PHA reaction, an index of T-cell-mediated immunocompetence) and of some parameters traditionally considered important for chick survival, such as egg mass and chick growth. Two statistical approaches were used: parent–offspring regression and full-sibling intra-clutch repeatability. The repeatability of other parameters that reflect egg quality (egg proteins, lipids, and carotenoids) and of substances that confer innate immunity (lysozyme and avidin) was also investigated. In agreement with previous studies, we found nonsignificant heritability for cell-mediated immunocompetence. In contrast, there were significant repeatabilities of chick mass and several egg characteristics (mass, size, total proteins), while lipid and carotenoid concentrations were not repeatable. For the first time in birds, we found significant repeatability of two molecules, lysozyme and avidin, that confer innate immunity to the developing embryo.
The influence of habitat patch attributes on coyote group size and interaction in a fragmented landscape
Authors: Atwood Todd C
Published: March 2006

From February 2000 to January 2002, I investigated correlates of landscape fragmentation with coyote (Canis latrans Say, 1823) group size and resulting effects on within-group spatial interaction in west-central Indiana, USA, to determine whether habitat patch dispersion and attributes mediated group maintenance and persistence. Twenty-one radio-collared coyotes were assigned to 15 social groups; group territories were then classified as having dispersed (n = 10) or aggregated (n = 5) resource patches. Group size was larger in territories with aggregated patches and was directly correlated to forest area and inversely correlated to corridor area (top-ranked model: group size = β0+ forest area – corridor area; AICc = 

–2.12, ΔAICc = 0.0, ωi = 0.67). Territories with aggregated patches had proportionally more forest (mean = 0.41, SE = 0.02) and less corridor (mean = 0.01, SE = 0.002) habitats than territories with dispersed patches (forest area: mean = 0.11, SE = 0.01; corridor area: mean = 0.03, SE = 0.002). Within-group spatial interaction was not influenced by patch dispersion. I suggest that differences in territory and group sizes relative to patch dispersion reflect the complex combination of environmental pressures present in human-dominated landscapes and their potential to perturb canid social organization.
Temperature effects on swimming performance, energetics, and aerobic capacities of mature adult pink salmon (Oncorhynchus gorbuscha) compared with those of sockeye salmon (Oncorhynchus nerka)
Authors: MacNutt Meaghan J , Hinch Scott G , Lee Chris G , Phibbs James R , Lotto Andrew G , Healey Michael C , Farrell Anthony P
Published: March 2006

We assessed the prolonged swimming performance (Ucrit), metabolic rate (M-dotO2-minand M-dotO2-max), and oxygen cost of transport (COT) for upper Fraser River pink salmon (Oncorhynchus gorbuscha (Walbaum, 1792); 53.5 ± 0.7 cm FL) and sockeye salmon (Oncorhynchus nerka (Walbaum, 1792); 59.3 ± 0.8 cm FL) across a range of naturally occurring river temperatures using large Brett-type swim tunnel respirometers. Pink salmon were capable of similar relative critical swimming speeds (Ucrit) as sockeye salmon (2.25 FL·s–1), but sockeye salmon swam to a higher absolute Ucrit(125.9 cm·s–1) than pink salmon (116.4 cm·s–1) because of their larger size. Nevertheless, three individual pink salmon (Ucrit-max = 173.6 cm·s–1) swam faster than any sockeye salmon (Ucrit-max = 157.0 cm·s–1), indicating that pink salmon are far better swimmers than has been previously assumed. Metabolic rate increased exponentially with swimming speed in both species and was highest for pink salmon, but swimming efficiency (i.e., COT) did not differ between species at their optimal swimming speeds. The upper and lower limits of metabolism did not differ between species and both M-dotO2-minand M-dotO2-maxincreased exponentially with temperature, but aerobic costs of transport were independent of temperature in both species. Strong thermal dependence of both swimming performance and COT were expected but not demonstrated in either species. Overall, a higher degree of inter-individual variability in pink salmon swim performance and capacity suggests that this species might not be as locally adapted to particular river migration conditions as are sockeye salmon.
Gorging on gobies: beneficial effects of alien prey on a threatened vertebrate
Authors: King R B , Ray J M , Stanford K M
Published: March 2006

Invasive species often have rapid and far-reaching negative impacts on populations and ecological communities. These effects are most common when invasive species have few competitors or predators. Although higher level carnivores do consume invasive species, quantitative effects of new and abundant food sources on predators have rarely been documented and, as a consequence, potentially positive effects of invasive species may be under appreciated. We investigated the effects of the invasive round goby (Neogobius melanostomus (Pallas, 1814)) on diet composition, growth rate, and body size of the Lake Erie Water Snake (Nerodia sipedon insularum (Conant and Clay, 1937)), which is threatened in the USA and endangered in Ontario, Canada. Water Snakes have shifted their diet, and round gobies now constitute >92% of prey consumed. This shift in diet has occurred in just one or two Water Snake generations, yet has resulted in more rapid growth and attainment of larger body size in Water Snakes. These positive effects may reduce predation, speed reproductive maturity, increase offspring production, and fuel population growth of this threatened species.
Inoculative freezing promotes winter survival in hatchling diamondback terrapin,Malaclemys terrapin
Authors: Baker P J , Costanzo J P , Herlands R , Wood R C , Lee, Jr. R E
Published: March 2006

We investigated the hibernation ecology and cold hardiness of hatchling diamondback terrapins, Malaclemys terrapin (Schoepf, 1793), an estuarine species that reaches 42°N along the Atlantic Ocean. During 3 years of study, about 50% of the nests we monitored harboured hatchlings during winter, and the majority (87%) of these individuals survived despite being intermittently exposed to subfreezing temperatures. Most such exposures were brief (ca. 12 h) and mild (minimum temperature: ca. –1.2 °C); however, turtles were occasionally subjected to longer chilling episodes and lower temperatures. In laboratory experiments, hatchlings supercooled extensively, attaining ca. –15 °C before spontaneously freezing. However, they were highly susceptible to inoculative freezing through contact with external ice and (or) ice-nucleating agents, which occur in nesting soil. Therefore, freeze avoidance through supercooling does not appear to be a viable cold-hardiness strategy in these turtles. Hatchlings subjected to experimental freezing survived exposure to temperatures as low as –3.0 °C, suggesting that freeze tolerance may account for the high winter survival observed in natural nests. We conclude that freeze tolerance in hatchling M. terrapin is promoted by high susceptibility to inoculation, which is known to moderate freezing, allowing cells time to adapt to the attendant physical and osmotic stresses.
Distribution of boreal toad populations in relation to estimated UV-B dose in Glacier National Park, Montana, USA
Authors: Hossack Blake R , Diamond Stephen A , Corn Paul Stephen
Published: March 2006

A recent increase in ultraviolet B radiation is one hypothesis advanced to explain suspected or documented declines of the boreal toad (Bufo boreas Baird and Girard, 1852) across much of the western USA, where some experiments have shown ambient UV-B can reduce embryo survival. We examined B. boreas occupancy relative to daily UV-B dose at 172 potential breeding sites in Glacier National Park, Montana, to assess whether UV-B limits the distribution of toads. Dose estimates were based on ground-level UV-B data and the effects of elevation, local topographic and vegetative features, and attenuation in the water column. We also examined temporal trends in surface UV-B and spring snowpack to determine whether populations are likely to have experienced increased UV-B exposure in recent decades. We found no support for the hypothesis that UV-B limits the distribution of populations in the park, even when we analyzed high-elevation ponds separately. Instead, toads were more likely to breed in water bodies with higher estimated UV-B doses. The lack of a detectable trend in surface UV-B since 1979, combined with earlier snow melt in the region and increasing forest density at high elevations, suggests B. boreas embryos and larvae likely have not experienced increased UV-B.
Seasonal metabolism of juvenile green turtles (Chelonia mydas) at Heron Island, Australia
Authors: Southwood A L , Reina R D , Jones V S , Speakman J R , Jones D R
Published: March 2006

We investigated seasonal changes in the energetics of juvenile green turtles (Chelonia mydas (L., 1758)) (9.8–23.8 kg) from a resident population on the southern Great Barrier Reef. Doubly labeled water was used to determine water flux and field metabolic rate (FMR) of green turtles during summer (mean water temperature (TW) = 25.8 °C) and winter (mean TW = 21.4 °C), and muscle tissue was collected for analysis of thermal sensitivity of metabolic enzyme activity. There was no significant seasonal difference in total body water (TBW) content (73.7% and 75.1% of body mass in summer and winter, respectively) or water flux (7.5% and 6.1% of TBW per day in summer and winter, respectively). The mean FMR during winter (81 ± 15 kJ·kg–1·d–1) was 43% lower than that during summer (142 ± 33 kJ·kg–1·d–1), but the seasonal difference in FMR marginally failed to reach statistical significance (P = 0.17). Thermal dependence of citrate synthase, lactate dehydrogenase, and pyruvate kinase activity was relatively low (Q10 = 1.20–1.68) over the range of temperatures experienced by turtles during summer and winter, and there were no significant seasonal differences in enzyme activity. In summary, juvenile green turtles experience only moderate changes in metabolism within the temperature range and environmental conditions experienced seasonally at this subtropical site.
Environmental complexity reduces tadpole predation by water bugs
Authors: Kopp K , Wachlevski M , Eterovick P C
Published: March 2006

We assessed the role of habitat structure in the outcome of predation by measuring how aquatic vegetation influences predation rates of water bugs (Belostoma oxyurum (Dufour, 1863), Hemiptera, Belostomatidae) on tadpoles of Dendropsophus minutus (Peters, 1872) and Scinax curicica Pugliese, Pombal, and Sazima, 2004 (Anura, Hylidae). Considering that previous studies have shown that some tadpole species preferentially use microhabitats with aquatic vegetation at sites in southeastern Brazil, we hypothesized that these tadpoles may select such complex microhabitats because they can offer some protection against co-occurring predatory aquatic insects. We used field enclosures containing tadpoles of D. minutus and S. curicica and one predator (B. oxyurum), placed on natural substrata in sites both with and without aquatic vegetation, according to treatment. We measured the combined effects of predation and habitat structure on the survivorship of tadpoles, monitoring each enclosure daily during 10 days to survey surviving tadpoles. Treatments with predators reduced tadpole survivorship significantly in relation to controls for both tadpole species. The interaction between predator and vegetation was also significant, predation rates being lower when vegetation was present.