bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological Disturbances in Fish Living in Coastal Water Polluted with Bleached Kraft Pulp Mill Effluents
Authors: Andersson Tommy , Förlin Lars , Härdig Jan , Larsson Åke
Published: June 2008

An extensive trial to examine physiological and biochemical changes in perch (Perca fluviatilis) inhabiting coastal waters polluted by bleached kraft mill effluents (BKME) has been carried out. The investigations were performed at four different times of year. Fish from a reference site and from sampling sites 2, 4.5, 8, and 10 km from the discharge point were examined. The results of the investigation show profound effects of BKME on several fundamental biochemical and physiological functions. Typical symptoms in perch from the polluted areas were reduced gonad growth, enlarged liver, and very strong induction of certain cytochrome P-450-dependent enzyme activities in the liver. Elevated levels of ascorbic acid in liver tissue and abnormal carbohydrate metabolism reflect the effluent's ability to cause metabolic disorders. Marked effects on the white blood cell pattern indicate a suppressed immune defence. Alterations in the red blood cell status and in the ion balance suggest that the demand for oxygen by certain tissues was increased and that gill function was impaired, respectively. The toxic effects were most pronounced in fish living up to 4.5 km from the discharge point, but some disturbances (e.g. cytochrome P-450 induction, reduced gonad size, and hematological alterations) were observed in fish caught as far as 8–10 km from the kraft bleach plant.
Blood Gases, Acid–Base Status, Ions, and Hematology in Adult Brook Trout (Salvelinus fontinalis) under Acid/Aluminum Exposure
Authors: Wood C. M. , Playle R. C. , Simons B. P. , Goss G. G. , McDonald D. G.
Published: June 2008

The relative importance of ionoregulatory and respiratory disturbances in brook trout (Salvelinus fontinalis) under acid/Al stress in soft water is dependent upon water pH and Ca2+levels. Trout acclimated to Ca2+ = 25 or 400 μequiv/L were fitted with arterial catheters and exposed to acid/Al for 10 d under flow-through conditions. Parameters monitored included pHa, [Formula: see text], [Formula: see text], HCO3−, ΔH+m, Na+, Cl−, K+, Ca2+, protein, lactate, glucose, hemoglobin, and hematocrit. Exposure to pH = 4.8 (no Al) at Ca2+ = 25 μequiv/L caused no mortality and negligible physiological disturbance. Addition of Al (333 μg/L or 12.3 μmol/L) resulted in >80% mortality (LT50 = 39.0 h) preceded by a marked decrease of plasma Na+and Cl−, a moderate disturbance of blood gases, but no acidosis. At higher Ca2+(400 μequiv/L), this same exposure (pH = 4.8, Al = 333 μg/L) caused similar mortality (LT50 = 38.5 h) but smaller ionic disturbances, much larger decreases in blood O2, increases in blood CO2, and respiratory acidosis. Exposure to pH = 4.4 (no Al) at Ca2+ = 25 μequiv/L caused 60% mortality (LT50 = 170.0) preceded by marked ionic disturbances and metabolic acidosis, but little change in blood gases. Addition of Al (333 μg/L) increased mortality to >80% (LT50 = 78.2 h) with smaller ionic but greater respiratory disturbances.
Physiological Evidence of Acclimation to Acid/Aluminum Stress in Adult Brook Trout (Salvelinus fontinalis). 1. Blood Composition and Net Sodium Fluxes
Authors: Wood C. M. , McDonald D. G. , Booth C. E. , Simons B. P. , Ingersoll C. G. , Bergman H. L.
Published: June 2008

Brook trout (Salvelinus fontinalis) adapt to chronic sublethal acid/Al stress. The accompanying acclimation confers greater resistance to short-term increases in Al and acidity. Adult trout were exposed in flowing soft water to eight combinations of pH (6.5, 5.2) × Ca2+(25, 400 μequiv/L) × Al (0, 75, 150 μg/L = 0, 2.8, 5.6 μmol/L). After 10 wk, blood sampling by caudal puncture revealed no significant variations in osmolality, plasma protein, or hemoglobin and only minor differences [Formula: see text] in plasma Na+and Cl−. Overall, most electrolytes were higher in fish exposed to higher water Al and/or Ca2+; only plasma Ca2+was directly depressed by low pH. Hematocrit was raised by both low pH and elevated Al. When trout naive to both acid and Al were challenged with pH = 4.8, Al = 333 μg/L under flow-through conditions, there were large negative whole-body Na+fluxes and marked depressions of plasma Na+and Cl−, hemoconcentration, and substantial mortality over 48 h. Prior exposure for 10 wk to pH = 5.2 plus either 75 or 150 μg Al/L prevented mortality and ameliorated or abolished these effects through a more rapid recovery of net Na+balance. Prior exposure to pH = 5.2 alone ameliorated these effects only slightly.
Sodium Transport In the Brook Trout,Salvelinus fontinalis: Effects of Prolonged Low pH Exposure in the Presence and Absence of Aluminum
Authors: McDonald D. G. , Millsgan C. L.
Published: June 2008

This study examined the effects of prolonged exposure [Formula: see text] to low Ca2+(25 versus 400 μequiv/L), low pH (pH 5.2 versus 6.5) with and without Al (150 μg/L) on Na+uptake in adult brook trout (Salvelinus fontinalis). Na+uptake (JinNa+) was assessed by measuring radiotracer disappearance from the medium at ambient Na+(79 μequiv/L) and in response to acute increases in ambient Na+. The relationship between JinNa+and [Na+] was best described by a linear model with the slope of the line a measure of transport activity. Transport activity increased as a result of prolonged low Ca2+exposure at pH 6.5, but declined in fish maintained at pH 5.2. These fish showed no compensation in response to low pH; there was no recovery in transport activity when pH was acutely raised to 6.5, and lower pH's further inhibited uptake. In contrast, the Na+transport activity of fish maintained at pH 5.2 and 150 μg Al/L was significantly greater than that of fish acclimated to pH 5.2 alone and indeed greater than pH 6.5 controls. This indicates that Al exposure induced a compensatory mechanism in the gills that was not seen with low pH exposure alone.
Effects of Low pH and Aluminum on Ventilation in the Brook Trout (Salvelinus fontinalis)
Authors: Walker R. L , Wood C. M. , Bergman H. L.
Published: June 2008

Brook trout (Salvelinus fontinalis) (acclimated to pH = 6.5, Ca2+ = 400 μequiv∙L−1), when exposed to acid (pH = 4.8, Ca2+ = 400 μequiv∙L−1) and Al (333 μg∙L−1), responded with a twofold increase in ventilation volume within the first 4 h of the challenge period (100 h). Increased ventilation stroke volume accounted for most of the change in ventilatory response; rate increased slightly. Although ventilation volume returned to prechallenge values by 6 h, coughing (flow reversal) and increased mucus production at the gills were notable throughout the challenge period. There were no significant changes in oxygen consumption or [Formula: see text], but hemoglobin oxygen content (micromoles per gram of hemoglobin) decreased by 20%. Arterial pH decreased as a result of both respiratory and metabolic disturbances. Exposure to acid (pH = 4.8, Ca2+ = 400 μequiv∙L−1) in the absence of Al resulted in similar initial changes in ventilation and blood acid–base status; however, ventilation remained elevated above the prechallenge values throughout the experiment (24 h). The transient increase and subsequent return of ventilation to prechallenge levels in the acid/Al-exposed fish suggests that Al interfered with the mechanism controlling the ventilatory response.
Computer-Driven Motor Control with Positional Memory for Mechanical Microscope Stage
Authors: Hiltz Kenneth S. , Dean Jonathan G. , Schwinghamer Peter , Belliveau Donald J.
Published: June 2008

A computerized control system for the X–Y mechanical stage of an inverted microscope was constructed using relatively inexpensive electrical components and requiring minimal modification to the stage. The control consists of two linear stepper motors, one for each axis, driven by commands from an IBM-compatible PC via a serial communications port and a simply constructed electrical controller. Menu-driven software regulates the motions of the steppers and allows keyboard input of data on the type and number of particles in settling chambers or on microscope slides. Frame locations of particles are stored automatically to facilitate reexamination of samples. The system allows samples to be removed and replaced while retaining the ability to relocate particles of interest.
Distribution of Shrimp (Pandalus borealis) Larvae and Hydrographic Pattern in the Northern Gulf of St Lawrence
Authors: Ouellet Patrick , Lefaivre Denis , Koutitonsky Vladimir
Published: June 2008

The large-scale spatial distribution of northern shrimp (Pandalus borealis) larvae was analyzed in the Gulf of St. Lawrence during the spring of 1986 and 1987. Although sites of emergence are related to the principal aggregation areas of adult shrimp, it appears that the currently fished aggregations may not represent isolated populations. The uniformity of developmental stages and the wide-spread distribution of the first larval stage were consistent with the hypothesis of synchronous larval emergence among the northern Gulf shrimp The structured pattern of larval spatial distribution was not correlated with the hydrographic structure within the different sectors of the Gulf (Mantel test; P > 0.05). Spatial correlograms showed that the highly structured spatial distribution pattern of stage I larvae evolved into a spatially random pattern by the time stage III larvae had developed. We suggest that biological or ecological dynamic processes such as larval mortality and development rates are more important than the hydrodynamics of the sectors in determining the structure of larval shrimp distribution Consequently, on a seasonal basis, the distribution of larval shrimp groups cannot be inferred from a study of the hydrographic pattern within the sectors at the scale of our analysis.
Measuring Fleet Capacity and Capacity Utilization
Authors: Smith Courtland L. , Hanna Susan S.
Published: June 2008

Fishing capacity measures the capability to catch fish. Capacity utilization is the actual effectiveness in catching fish; the ratio of catch to capacity. The factors comprising a fleet's capacity are the number and size of vessels, the technical efficiency of those vessels, and the time commitment of fishermen. Knowing the capacity utilization of a fleet is critical for evaluating management alternatives. This is true regardless of whether fisheries are managed with fleet controls or with individual controls. We illustrate the measurement of capacity utilization with the Oregon bottom trawl fishery, in which fleet capacity quadrupled between 1976 and 1982. From 1982 to 1985 capacity declined 30% due to economic problems in the industry and vessels finding better opportunities elsewhere. Capacity measurement is necessary to assess management-induced changes in controlled fisheries. Controlling capacity requires addressing all the elements associated with capacity growth. Examination of the components of fleet capacity reveals an array of management options.
Treatment of Data for Duplicated Gene Loci in Mixed-Stock Fishery Analysis
Authors: Waples Robin S. , Aebersold Paul B.
Published: June 2008

Isoloci (pairs of duplicated loci with a predominance of shared alleles of identical electrophoretic mobility) are common in salmonid fishes and present special problems for the analysis of mixed-stock fisheries. The method currently used to treat isolocus data (which assumes that allele frequencies at both loci are the same) leads to bias if the true frequencies (P, Q) are not identical. Using simulated mixtures drawn from populations with (1) hypothetical allele frequencies and (2) allele frequencies observed at four isolocus systems in samples of chinook salmon from the Fraser River system, we show that a better method is to use the maximum likelihood estimates ([Formula: see text], [Formula: see text]) of allele frequencies at the individual loci. In simulations in which the population frequencies at the two loci of an isolocus pair differed, use of ([Formula: see text], [Formula: see text]) resulted in less error in estimating the true mixture proportions than did use of a single average frequency, whereas the two methods produced very similar results if population frequencies were identical at both loci.
Intrabiome Distributional Patterns of Lotic Macroinvertebrate Assemblages
Authors: Corkum Lynda D.
Published: June 2008

Macroinvertebrates were collected at five sites along each of three rivers within the eastern deciduous forest biome in spring, summer, and autumn. Macroinvertebrate density at sites in mixed land use areas was intermediate between high levels at sites in farmlands and low levels in forests. Cluster analysis using mean density of the 24 dominant taxa revealed three groupings of river sites each of which was consistently associated with a land use type. Clusters were poorly associated with season of collection, site location along rivers, and with specific river drainage. Hydropsychidae and Leptophlebiidae characterized forested sites. The assemblage associated with mixed Sand use areas included Psephenidae, Baetidae, Tricorythidae, and Heptageniidae. Farmland river sites were characterized by Ceratopogonidae, Corixidae, Oligochaeta, and Tricladida. The mixed land use group of river sites was faunistically more similar to sites in forested than in farmland areas. Forested sites were fast-flowing and had little benthic detritus; farmland sites were slow-flowing and had high levels of detritus. The biome dependency hypothesis, which predicts that similar assemblages of macroinvertebrates are likely to occur at river sites both within and among drainages if the basins occupy the same biome, was not largely supported because characteristic vegetation had been disturbed.
Changes in Growth and Reproduction of Harbour Porpoises, Phocoena phocoena, from the Bay of Fundy
Authors: Read Andrew j. , Gaskin David E.
Published: June 2008

Changes in the growth and reproduction of harbour porpoises from the Bay of Fundy are described by comparing samples collected in 1969–73 and 1985–88. The most pronounced change was an increase in the length of calves, from 92.1 cm (SE 1.6) in 1969–73 to 108 cm (SE 1.3) in 1985–88. Females in 1985–88 attained sexual maturity at a significantly younger age (3.44 yr) and shorter length (143 cm) than females from the older sample (3.97 yr and 147 cm). These changes may be attributable to an increase in prey availability to individual porpoises. This presumed increase in prey availability may have resulted from a decrease in porpoise density caused by incidental mortality in commercial fisheries, a simultaneous increase in prey abundance, or a combination of these factors.
How Reliable are Growth Back-Calculations Based on Otoliths?
Authors: Campana Steven E.
Published: June 2008

Growth back-calculations from otoliths assume that the relationship between fish and otolith length is linear through time. The final (or observed) individual fish-otolith ratios are then combined to prepare a fish-otolith regression for the population, upon which the subsequent back-calculations are based. However, recent studies have demonstrated that the fish:otolith size ratio varies systematically with somatic growth rate, resulting in relatively large otoliths in slow-growing fish. Such a growth effect will result in a fitted fish-otolith regression which differs significantly from that of the mean of the individual fish-otolith slopes. Fraser–Lee growth back-calculations made from such a regression consistently underestimate previous lengths at age. The bias may explain the apparent ubiquity of Lee's phenomenon. Back-calculation bias was eliminated through use of an algorithm defining individual fish-otolith trajectories and a biologically determined, rather than a statistically estimated, intercept. Adaptations of the biological intercept back-calculations procedure accurately predicted previous lengths in the presence of both stochastic error and time-varying growth rates. When used to reevaluate some published back-calculations, the biological intercept procedure resulted in more accurate values than those previously estimated, and reduced or eliminated the presence of Lee's phenomenon.
Effect of Temperature on the Chronic Toxicity of Arsenate to Rainbow Trout (Oncorhynchus mykiss)
Authors: McGeachy S. M. , Dixon D. G.
Published: June 2008

The effects of water temperature (5 or 15 °C) on the toxicity of arsenate to rainbow trout were examined over an 11-wk period. The fish were exposed to nominal arsenate concentrations set as fixed proportions of the 144-h LC50s for arsenate at their respective temperature (5 °C: 0, 1.5, 18, and 36 mg∙L−1; 15 °C: 0, 1.5, 9, and 18 mg∙L−1). Arsenate toxicity was assessed in terms of mortality, total arsenic concentration, wet weight, condition factor, liver and muscle glycogen levels, hepato- and splenosomatic indices, and histopathology. Contrary to the previously reported relationship between acute toxicity and temperature, trout were more tolerant of chronic exposure to arsenate at 15 °C than at 5 °C. While the high-exposure concentration (5 °C, 36 mg∙L−1; 15 °C, 18 mg∙L−1) fish at both temperatures attained the same internal arsenic concentration (2 to 3 μg∙g−1), up to 50% of those fish tested at 5 °C died. The whole-body arsenic concentrations in moribund trout were found to vary between 4 and 6 μg∙g−1, suggesting that a critical arsenic body-concentration is reached before death or toxicant insult occur.
Changes in the Composition of Snow Crab (Chionoecetes opilio) Participating in the Annual Breeding Migration in Bonne Bay, Newfoundland
Authors: Ennis G. P. , Hooper R. G. , Taylor D. M.
Published: June 2008

Sexually-paired snow crabs (Chionoecetes opilio) participating in an annual spring breeding migration to shallow water in Bonne Bay, Newfoundland were collected by SCUBA divers from 1984 to 1989. In 1984 the breeding pairs were composed mainly of relatively large, old-shell animals of both sexes, but by 1988 much smaller animals, most of which were new-shell, dominated the migration. Evidence from research fishing indicates that these changes are related to a rapid decline in what was characteristically a virgin population in 1984 and a coinciding strong pulse of recruitment into the breeding component of the population. A very high incidence of small, subcommercial males participating in the 1988 and 1989 breeding migrations demonstrates a capacity for maintaining a high level of reproductive potential in a snow crab population despite high exploitation rates on larger animals in the male-only fishery for this species. The strong recruitment pulse which occurred in Bonne Bay as the virgin population declined after 1984 also indicates a capacity for enhanced annual production within a snow crab population when exploitation rates are high.
Relative Importance of Seasonal, Short-Term pH Disturbances During Discharge Variation on a Stream Ecosystem
Authors: Hall Ronald J.
Published: June 2008

Effects of short-term, experimental pH reduction on water chemistry and structure of benthic invertebrate communities were investigated in a south-central Ontario stream during spring and fall. With increased acidity, inorganic monomeric Al and Ca concentrations were significantly increased in stream water during spring and fall, whereas Fe, Mn, and Zn concentrations did not change. Total Al and DOC concentrations in stream water showed no constant pattern. Benthic density and generic richness during spring decreased in mineral, but not organic sediments. Total drift density did not change, but mayflies increased in the drift. In contrast, in the fall, benthic density and generic richness fluctuations were not correlated with pH disturbance, whereas drift density increased significantly during elevated acidity. Diversity and evenness of benthic invertebrates did not change above or below pH disturbance in either season. Non-metric multidimensional scaling analysis showed that discharge was the primary correlate of spring drift, whereas pH played a secondary role. In autumn, analyses demonstrated that Ca and DOC were predominant factors associated with increased drift but were related to hydrology. This study highlights the interrelationship between life history strategies of benthic invertebrates and the frequency and intensity of physical (discharge fluctuations) and chemical (pH depressions) disturbances.
Particulate light attenuation in a large subtropical lake
Authors: Havens Karl E.
Published: June 2008

Deviations among Carlson's trophic state index values were used to quantify a 12-year history of seston composition and underwater light attenuation in Lake Okeechobee, Florida, U.S.A. Deviations between chlorophyll a, total phosphorus, and transparency-based trophic state indices indicated that (i) light attenuation is generally dominated by phosphorus-rich abiotic particles; (ii) abiotic light attenuation is maximal in a central lake region overlying soft mud sediments, and minimal in a near-littoral region overlying hard sand; and (iii) there has been a progressive increase in the relative contribution of algal pigments to total light attenuation between 1980 and 1992. Coincident with that 12-year trend, there have been declines in external nitrogen loads, lake water nitrogen:phosphorus ratios, and wind velocities. Surface water temperatures in the lake have significantly increased. Explanations for the trend in light attenuation include (i) more favorable meteorological conditions for algal growth, which increased the contribution of algae to overall light attenuation and (ii) reduced nitrogen:phosphorus ratios favoring proliferation of buoyant cyanobacteria, which are more effectively sampled by surface water monitoring. In either case, the trend did not coincide historically with enhanced nutrient loading, the common cause of algal proliferation in lakes.
Effects of cadmium on the foraging behavior and growth of juvenile bluegill, Lepomis macrochirus
Authors: Bryan Miehael D. , Atchison Gary J. , Sandheinrich Mark B.
Published: June 2008

Standardized test protocols for assessing chemical hazards to aquatic organisms inadequately consider behavioral effects of toxicants; yet, organisms behaving abnormally in the wild have reduced growth, reduced fitness, and high mortality. We determined the chronic effects of cadmium (0, 30, 60, 120, and 240 μg∙L−1) on juvenile bluegill (Lepomis macrochirus) foraging behavior and growth rates in functional response experiments, each using different sized Daphnia as prey. Bluegill consumption rate increased with prey density. Cadmium-exposed fish initially attacked fewer prey per unit of time than unexposed fish, with subsequent recovery to control-level consumption rates determined by cadmium concentration and prey size. The degree of change (over time) in the number of Daphnia attacked per 30 s was the most consistently sensitive behavioral measure of sublethal stress in exposed bluegill; the lowest observed effect concentration (LOEC) was 37.3 μg Cd∙L−1. Effects on prey attack rates (attacks/30 s) were inversely related to prey size; cadmium had the greatest effect on bluegill foraging on the smallest prey. Cadmium had no effect on prey capture efficiency or handling time. Growth in bluegill length and weight was reduced (P ≤ 0.019) by all cadmium concentrations and was a more sensitive end point than were the foraging behaviors.
Effect of predation by Sacramento squawfish (Ptychocheilus grandis) on habitat choice of California roach (Lavinia symmetricus) and rainbow trout (Oncorhynchus mykiss) in artificial streams
Authors: Brown Larry R. , Brasher Anne M.
Published: June 2008

We studied the effects of predatory Sacramento squawfish (Ptychocheilus grandis) on habitat choice of juvenile California roach (Lavinia symmetricus), adult roach, and juvenile rainbow trout (Oncorhynchus mykiss) in artificial streams. In single-prey trials, the proportion of fish found in pool habitat declined in the presence of squawfish for juvenile roach (from 0.55 to 0.00), adult roach (from 0.88 to 0.13), and juvenile rainbow trout (0.70 to 0.15). The presence of squawfish did not affect the use of riffle and edge habitats. Of the fish found in shallow water, the proportion found in edge habitat declined from juvenile roach (0.95) to adult roach (0.80) to juvenile rainbow trout (0.23). We also conducted experiments designed to simulate invasion of an area by squawfish, in which adult roach and juvenile rainbow trout were tested together in the presence and absence of squawfish. The proportion of prey in pool habitat in the presence of squawfish was greater in the two-prey trials than in the single-prey trials for both adult roach (0.31 and 0.13, respectively) and juvenile rainbow trout (0.33 and 0.15, respectively). These results support field evidence that squawfish are an important force in determining the spatial structure of native stream fish assemblages.
Comparative energetics and the development of bioenergetics models for sympatric estuarine piscivores
Authors: Hartman Kyle J. , Brandt Stephen B.
Published: June 2008

Bioenergetics models for striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis) were developed from laboratory experiments on metabolism and consumption. Size-specific rates of consumption and metabolism were similar for bluefish and weakfish and higher than those for striped bass. Temperature effects on maximum consumption rate (Cmax) differed with fish size. Cmax of young fish (30 g) increased with temperature, then declined rapidly at higher temperatures; Cmax for larger fish of all three species (100–3000 g) increased rapidly to the maximum rate, but leveled off at higher (25–30 °C) temperatures. Results of Cmax experiments suggest that extrapolation of the temperature dependency of small fish to larger fish, as is commonly done, may misrepresent potential growth at higher temperatures. Independent model validation using laboratory experiments found consumption estimates (from growth) to be within −1.4 to +4.5% of known values for all species at temperatures above 19 °C; however, at 6.9°C consumption by striped bass was overestimated by 20–46%. Model estimates of growth (from consumption) were within −7.1 to +30.1% of known values in all validations. Overall, the growth physiology of the three species appeared to be related to the water temperatures encountered during estuarine residency and production.
Vitamin A stores, teratogenesis, and EROD activity in white sucker,Catostomus commersoni, from Rivière des Prairies near Montréal and a reference site
Authors: Branchaud Alain , Gendron Andrée , Fortin Réjean , Spear Philip A. , Anderson Perry D.
Published: June 2008

White sucker, Catostomus commersoni, were sampled from the Rivière des Prairies in the vicinity of Montréal and the upper reaches of the Ottawa River in La Verendrye Park (reference site). Rivière des Prairies fish had lower liver retinol (p ≤ 0.0001) and retinyl palmitate (p ≤ 0.0001) concentrations than fish from the reference site. Rivière des Prairies females and males contained only 9.3 and 30%, respectively, of the vitamin A stores detected in reference fish. Age was an important variable. Covariance analysis revealed that the the rate of retinyl palmitate storage with age was higher (p ≤ 0.0001) for sucker at the reference site. Retinaldehyde was the major retinoid in eggs; however, concentrations were not different between the two sites. The prevalence of malformations was 1.49% among Rivière des Prairies larvae, greater (p ≤ 0.002) than that of the reference group. Eye deformities (i.e., anophthalmia, synopsia) were 11.8 times more prevalent in the Rivière des Prairies larvae. Ethoxyresorufin-O-deethylase (EROD) was greater (p ≤ 0.0003) in the Rivière des Prairies fish. Liver EROD activity in adult females was positively correlated (R = 0.81; p ≤ 0.0004) with the prevalence of deformities of their progeny. Semiquantitative results showed that embryo mortality also tended to increase with EROD activity.
The effects of small-scale turbulence on the ingestion rate of fathead minnow (Pimephales promelas) larvae
Authors: Landry François , Miller Thomas J. , Leggett William C.
Published: June 2008

Small-scale turbulence increases encounter rates between planktonic predators and their prey. It has been hypothesized to lead to an increase in feeding by fish larvae, yet this has rarely been tested experimentally. We investigated the effects of turbulence on feeding by fathead minnow (Pimephales promelas) larvae to test the null hypothesis of no effect of turbulence on ingestion. In one experiment, larvae were exposed to four turbulent velocities from 0 to 2 cm∙s−1 at a single prey concentration. Data analysis led to a rejection of the null hypothesis. Moreover these data suggested a significant nonlinear response of ingestion to increasing turbulence. In a second experiment, we varied turbulence and prey concentrations (15, 50, and 500 prey/L) simultaneously. We rejected the null hypothesis of no effect of turbulence for all prey concentrations. Results differed among prey concentrations. We observed a negative linear response for the two lower prey concentrations, but a domed response at 500 prey/L. We conclude that turbulence does influence ingestion, but not as suggested by an extension of encounter models. Thus, turbulence may not always be beneficial in the field.
Groundwater and the selection of spawning sites by brook trout (Salvelinus fontinalis)
Authors: Curry R. Allen , Noakes David L. G.
Published: June 2008

Spawning areas selected by brook trout (Salvelinus fontinalis) displayed variable relationships to discharging groundwater across geologic regions. In Canadian Shield waters, spawning was associated with areas of distinct, discharging groundwater. The specific mechanism of selection could not be determined. Groundwater did not appear to influence the selection of individual redd sites within these discharge areas. Competition among females for the opportunity to spawn in a limited area defined by the discharging groundwater appeared to control the selection of redd sites. In southwestern Ontario streams, discharging groundwater was prominent throughout areas of spawning both at redds and at adjacent, nonspawning substrates (≤7 m). Consequently, relationships between groundwater and spawning site selection were ambiguous. On the unglaciated plateau of central Pennsylvania, no groundwater was observed in redds or nonspawning substrates in streams. Brook trout management programmes must consider these groundwater relationships and therefore the impact of land use on groundwater quality and quantity.
Groundwater and the incubation and emergence of brook trout (Salvelinus fontinalis)
Authors: Curry R. Allen , Noakes David L. G. , Morgan George E.
Published: June 2008

Groundwater was observed to discharge through brook trout (Salvelinus fontinalis) redds during the November to April incubation period in Canadian Shield waters. Groundwater was important for protecting redds from infiltrating surface water and ice. Physical and chemical characteristics of individual redd environments were similar during the incubation period. Substrate temperature and oxygen levels were reduced in nonredd substrates 100 cm from redds. The stability of discharge, temperature, dissolved oxygen, and specific conductance during incubation was similar between redd and nonredd substrates (≤100 cm away). The quality of redd habitats and embryo survival did not appear to be related to female competition for redd sites or time of spawning. There was evidence of density-dependent control of spawning success and the adaptive nature of alevin emergence behaviour in Canadian Shield waters.
Implications of increased UV-B induced photoreduction: iron(II) enrichment stimulates picocyanobacterial growth and the microbial food web in clear-water acidic Canadian Shield lakes
Authors: Auclair J. C.
Published: June 2008

Ozone depletion and associated increases in UV-B radiation could increase the photoreduction of iron in Canadian Shield lakes of the boreal forest zone. Since photoreduced iron(II) is more soluble than iron(III), and the reoxidation rate slower in acidic (pH = 5–6) lakes, phytoplanktonic growth and (or) species composition may be altered where iron is growth limiting. This hypothesis was tested by amending herbivore-free lake-water enclosures with phosphorus, phosphorus and iron(II), or phosphorus, ammonium, and iron(II) in lac Tantaré, a clear-water acidic lake in Quebec. In herbivore-free unenriched control enclosures, phytoplanktonic abundance doubled within 48 h, demonstrating unequivocally that herbivore grazing (top-down control) intensity controls phytoplanktonic abundance in early spring in this lake. However, at chlorophyll a concentrations 2–3 times the ambient lake levels, picocyanobacterial production and abundance were greater in the phosphorus and iron enclosures, relative to the phosphorus-only enclosures. This resulted in enhanced growth of the indigenous chrysophytes presumably through increased mixotrophy. In spite of a 10-fold increase in nanoflagellate abundance, we were unable to discern any strong competitive interactions among the mixotrophic chrysophytes. This strongly suggests that most if not all of their iron quotas are obtained from their picoplanktonic prey.
Genetic and cytogenetic analysis of the fruit flyRhagoletis cerasi(Diptera: Tephritidae)
Authors: Kounatidis Ilias , Papadopoulos Nikolaos , Bourtzis Kostas , Mavragani-Tsipidou Penelope
Published: June 2008

The European cherry fruit fly, Rhagoletis cerasi , is a major agricultural pest for which biological, genetic, and cytogenetic information is limited. We report here a cytogenetic analysis of 4 natural Greek populations of R. cerasi, all of them infected with the endosymbiotic bacterium Wolbachia pipientis . The mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of this pest species are presented here. The mitotic metaphase complement consists of 6 pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement has shown a total of 5 long chromosomes (10 polytene arms) that correspond to the 5 autosomes of the mitotic nuclei and a heterochromatic mass corresponding to the sex chromosomes. The most prominent landmarks of each polytene chromosome, the “weak points”, and the unusual asynapsis of homologous pairs of polytene chromosomes at certain regions of the polytene elements are also presented and discussed.
Molecular characterization of the waxy locus in sorghum
Authors: McIntyre C. L. , Drenth J. , Gonzalez N. , Henzell R. G. , Jordan D. R.
Published: June 2008

A comparison of approximately 4.5 kb of nucleotide sequence from the waxy locus (the granule-bound starch synthase I [GBSS I] locus) from a waxy line, BTxARG1, and a non-waxy line, QL39, revealed an extremely high level of sequence conservation. Among a total of 24 nucleotide differences and 9 indels, only 2 nucleotide changes resulted in altered amino acid residues. Protein folding prediction software suggested that one of the amino acid changes (Glu to His) may result in an altered protein structure, which may explain the apparently inactive GBSS I present in BTxARG1. This SNP was not found in the second waxy line, RTx2907, which does not produce GBSS I, and no other SNPs or indels were found in the approximately 4 kb of sequence obtained from RTx2907. Using one indel, the waxy locus was mapped to sorghum chromosome SBI-10, which is syntenous to maize chromosome 9; the waxy locus has been mapped to this maize chromosome. The distribution of indels in a diverse set of sorghum germplasm suggested that there are two broad types of non-waxy GBSS I alleles, each type comprising several alleles, and that the two waxy alleles in BTxARG1 and RTx2907 have evolved from one of the non-waxy allele types. The Glu/His polymorphism was found only in BTxARG1 and derived lines and has potential as a perfect marker for the BTxARG1 source of the waxy allele at the GBSS I locus. The indels correctly predicted the non-waxy phenotype in approximately 65% of diverse sorghum germplasm. The indels co-segregated perfectly with phenotype in two sorghum populations derived from crosses between a waxy and a non-waxy sorghum line, correctly identifying heterozygous lines. Thus, these indel markers or sequence-based SNP markers can be used to follow waxy alleles in sorghum breeding programs in selected pedigrees.
A comparative study of convicilin storage protein gene sequences in species of the tribe Vicieae
Authors: Sáenz de Miera L. E. , Ramos J. , Pérez de la Vega M.
Published: June 2008

Convicilins, a set of seed storage proteins, differ from vicilins, a related group of seed storage proteins, mainly because of the presence of the N-terminal extension, an additional sequence of amino acids in the sequence corresponding to the first exon. Convicilins have been described only in species of the legume tribe Vicieae. One or two genes for convicilins have been identified in most species of this tribe. The genus Pisum is the main exception, since two genes have been identified in most of its species. Thirty-four new convicilin gene sequences from 29 different species ( Lathyrus , Lens , Pisum, and Vicia spp.) have been analyzed here. Convicilin gene sequences are generally organized in 6 exons, but in some instances one of the internal introns (2nd or 4th) is lost. In these 29 species, the N-terminal extension is formed by a stretch of 99 to 196 amino acids particularly rich in polar and charged amino acids (on average, it contains 29.43% glutamic acid and 15.38% arginine residues). This N-terminal extension has the characteristics of an intrinsically unstructured region (IUR), one of the categories of protein “degenerate sequences”. A comparative analysis indicates that the N-terminal extension sequence has evolved faster than the surrounding sequence, which is common to all vicilins, and it evolved mainly through a series of duplications of short internal sequences and triplet expansions, the predominant one being GAA. This agrees with the evolution of IURs, which is faster than the evolution of surrounding sequences and is mainly due to replication slippage and unequal crossover recombination. Alternative maximum-likelihood trees of phylogenetic relationships among the 29 Vicieae species based on the convicilin exon sequences are presented and discussed.
Some applications of Ricci flow in physics
Authors: Woolgar E
Published: June 2008

I discuss certain applications of the Ricci flow in physics. I first review how it arises in the renormalization group (RG) flow of a nonlinear sigma model. I then review the concept of a Ricci soliton and recall how a soliton was used to discuss the RG flow of mass in two dimensions. I then present recent results obtained with Oliynyk on the flow of mass in higher dimensions. The final section discusses how Ricci flow may arise in general relativity, particularly for static metrics.PACS Nos.: 02.40Ky, 02.30Ik, 04.20.–q
Fermions in low-dimensional systems and the transition between bulk and surface properties
Authors: Dick R
Published: June 2008

We discuss three formalisms for the description of Fermions in low-dimensional systems. Then we consider dimensionally hybrid Hamiltonians with mixed three-dimensional and two-dimensional kinetic terms. These Hamiltonians yield particular dimensionally hybrid Green’s functions with interesting prospects for the description of the transition between two-dimensional and three-dimensional behavior of particles in the presence of attractive interface potentials.PACS Nos.: 05.30.Fk, 71.10.Pm, 73.20.–r
Momentum average approximations for the Holstein polaron
Authors: Berciu M
Published: June 2008

We present a novel approach for obtaining simple yet highly accurate approximations for interacting problems. We use the Holstein polaron as an example and show that the predictions of the so-called Momentum Average approximation are in good agreement with results of numerical simulations over most of the parameter space, and become exact in various asymptotic limits. The resulting Green’s function satisfies exactly the first six spectral weight sum rules, and all higher order sum rules are satisfied with great accuracy. Furthermore, the accuracy can be improved systematically, at a slightly increased computational cost. PACS Nos.: 71.38.–k, 72.10.Di, 63.20.Kr
A classical spinor approach to the quantum/classical interface
Authors: Baylis W E , Keselica J D
Published: June 2008

A promising approach to the quantum/classical interface is described. It is based on a formulation of relativistic classical mechanics in the Clifford algebra of physical space. Spinors and projectors arise naturally and provide powerful tools for solving problems in classical electrodynamics. They also reproduce many quantum results, allowing insight into quantum processes.PACS Nos.: 03.65.Ca, 03.65.Ta, 04.20.Gz, 02.10.Xm
Unparticles and charge parity violation
Authors: Chen C H , Geng C Q
Published: June 2008

Unparticles proposed by Georgi carry charge parity (CP) conserving phases in their propagators. In this paper, we review our recent works on CP violation due to the peculiar phases of unparticles. We use the decays Bd → π+ π– and Bd → [Formula: see text]–[Formula: see text]+ as the illustrators to show the influences of these phases on the direct CP asymmetries. In particular, we emphasize that if a nonzero CP asymmetry is found in Bd → [Formula: see text]–[Formula: see text]+, it is definitely an indication of the existence of unparticles.PACS Nos.: 12.60.–i 11.30.Er 13.20.He 14.40.Nd
Thermodynamics of rotating NUT-charged spacetimes
Authors: Ghezelbash A M , Mann R B , Sorkin R D
Published: June 2008

We consider the family of “Kerr–Bolt” solutions (characterized by three real parameters: a size, a Newman–Unti–Tamburino (NUT) charge, and a spin rate) and evaluate their mass, angular momentum, and entropy according to the boundary counterterm prescription. Demanding the absence of any singularities reduces the number of free parameters and imposes some restrictions on the thermodynamics of solutions.PACS Nos.: 04.20.–q, 04.70.Dy, 65.40.Gr
Chebyshev-derived spindown parameters for gravitational wave signals from pulsars
Authors: Valluri S R , Fried M D
Published: June 2008

The master equation described by Badri Krishnan et al. (Phys Rev. D, 70, 082001 (2004)) for the time-frequency pattern using the F-statistic is studied in the context of Chebyshev-polynomial modified spindown parameters for the case of gravitational wave pulsar signals. The Chebyshev-polynomial method enables an analytic and numeric evaluation of the Fourier transform (FT) for both the non-demodulated and F-statistic demodulated FT.PACS Nos.: 04.30.Tv, 95.85.sz, 02.30.Gp, 02.40.Re
Wiener–Hopf analysis of the parallel plate wave guide with opposing rectangular dielectric-filled grooves
Authors: Tayyar I H , Büyükaksoy A , Işıkyer A
Published: June 2008

The purpose of the present work is to provide a rigorous analysis of the parallel plate wave guide with two opposing rectangular grooves of different depths and filled with different dielectric materials. This configuration may be used as a band-stop filter. The representation of the solution to the three-part mixed boundary-value problem in terms of Fourier integrals leads to a couple of simultaneous modified Wiener–Hopf equations. By using the analytical properties of the functions that occur, the simultaneous modified Wiener–Hopf equations are reduced to the solution of four infinite systems of linear algebraic equations. These systems are solved numerically, and the band-stop filter characteristics of the reflection coefficient are studied in terms of frequency, groove sizes, and the parameters of the filling dielectric material.PACS Nos.: 42.25.Bs, 42.25.Gy, 42.82.Et
Flat space holography
Authors: Mann R B
Published: June 2008

The implementation of holography in gravitational physics has its most concrete realization in the context of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence conjecture, an implication of which is that counterterms from the boundary CFT can be understood as surface terms that render the variational principle finite and well-defined for the gravity theory in the bulk. I discuss recent developments that show how such gravitational counterterms can be deployed for asymptotically flat spacetimes in any spacetime dimension d ≥ 4. These actions yield conserved quantities at spacelike infinity that agree with the usual Arnowitt–Deser–Misner results but are more general. This approach removes the need for ill-defined background subtraction methods and suggests the possibility of obtaining a dual field theory to gravity theories in asymptotically flat spacetimes.PACS Nos.: 04.20.Ha, 04.60.–m, 11.25.Tq
Semiclassical horizons
Authors: Dasgupta A
Published: June 2008

The entropy of apparent horizons is derived using coherent states or semiclassical states in quantum gravity. The leading term is proportional to area for large horizons, and the correction terms differ according to the details of the graph that is used to regularize the quantum gravity phase space variables.PACS Nos.: 04.60.Pp, 04.70.Dy
Target-finding time for microtubules interacting with catastrophe-suppressing drugs
Authors: Feizabadi M S
Published: June 2008

The target-finding time for microtubules interacting with catastrophe-suppressing drugs is investigated in this study. In the steady state of microtubules interacting with catastrophe-suppressing drugs, two types of microtubules exist, those with and those without drug tips. This work shows that microtubules in the first group are slower in finding a target than those in the second group. This result is consistent with experimental findings.PACS Nos.: 87.16.Ka, 87.16.Ac, 87.10.+e, 87.15.Rn
Two physical characteristics of numerical apparent horizons
Authors: Booth I
Published: June 2008

This article translates some recent results on quasilocal horizons into the language of (3 + 1) general relativity to make them more useful to numerical relativists. In particular, quantities are described that characterize how quickly an apparent horizon is evolving and how close it is to either equilibrium or extremality.PACS Nos.: 04.20.Cv, 04.25.Dm, 04.70.Bw
Renormalization group determination of the five-loop effective potential for massless scalar field theory
Authors: Chishtie F A , McKeon D G.C. , Steele T G
Published: June 2008

The five-loop effective potential and the associated summation of subleading logarithms for O(4) globally symmetric massless λϕ4 field theory in the Coleman–Weinberg renormalization scheme d4V / dϕ4|ϕ=μ = λ (where μ is the renormalization scale) is calculated via renormalization-group methods. An important aspect of this analysis is conversion of the known five-loop renormalization-group functions in the minimal-subtraction (MS) scheme to the Coleman–Weinberg scheme.PACS Nos.: 11.30.Qc, 11.10.Hi, 11.15.Tk, 12.15.Lk
Long-range coupling and scalable architecture for superconducting flux qubits
Authors: Fowler A G , Thompson W F , Yan Z , Stephens A M , Plourde B L.T. , Wilhelm F K
Published: June 2008

Constructing a fault-tolerant quantum computer is a daunting task. Given any design, it is possible to determine the maximum error rate of each type of component that can be tolerated while still permitting arbitrarily large-scale quantum computation. It is an under-appreciated fact that including an appropriately designed mechanism enabling long-range qubit coupling or transport substantially increases the maximum tolerable error rates of all components. With this thought in mind, we take the superconducting flux qubit coupling mechanism described in Plourde et al. (Phys. Rev. B, 70, 140501(R) (2004)) and extend it to allow approximately 500~MHz coupling of square flux qubits, 50 µm a side, at a distance of up to several mm. This mechanism is then used as the basis of two scalable architectures for flux qubits taking into account crosstalk and fault-tolerant considerations such as permitting a universal set of logical gates, parallelism, measurement and initialization, and data mobility.PACS No.: 03.67.Lx