bluuebunny/crossref_metadata_2025 huggingface dataset:
The Sask Craton and Hearne Province margin: seismic reflection studies in the western Trans-Hudson Orogen
Authors: Hajnal Z , Lewry J , White D , Ashton K , Clowes R , Stauffer M , Gyorfi I , Takacs E
Published: July 2005

A three-dimensional model of the regional crustal architecture of the western Trans-Hudson Orogen, based on the interpretation of 590 km of deep-sounding seismic reflection data and a comparable length of existing seismic reflection information, is presented. The seismic images identify the regional geometry of the basal detachment zone (Pelican thrust) that separates juvenile allochthonous terranes from the underlying Archean microcontinent (Sask craton). The Sask Craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike. During terminal collision, complete convergence of the RaeHearne and Superior continental blocks was precluded by the presence of the Sask Craton, resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material. Along regional tectonic strike, consistency of crustal structure across the RaeHearne margin  Reindeer zone boundary is established. Several phases of tectonic development, including multistage subduction and continentcontinent collision, are inferred for the western margin of the orogen. A bright, shallow (23.5 s two-way traveltime) band of reflectivity (Wollaston Lake reflector) imaged over ~150 000 km2 area is inferred to be a large post-orogenic mafic intrusion. A highly reflective, well-defined and structurally disturbed Moho discontinuity is mapped throughout the western Trans-Hudson Orogen. The present-day crustal architecture of the western Trans-Hudson Orogen is described in terms of the tectonic evolution within the region.
Lithospheric structure of the Trans-Hudson Orogen from seismic refraction - wide-angle reflection studies
Authors: Németh Balázs , Clowes Ron M , Hajnal Zoltan
Published: July 2005

The Trans-Hudson Orogen (THO) is the world's largest Paleoproterozoic orogenic belt. Data from three refraction profiles are used to investigate its lithospheric structure in Saskatchewan and Manitoba. R1 crosses the orogen from the Hearne craton on the west to the Superior craton on the east; R2 and R3 are along the orogen. P-wave velocity structural models are generated using a ray-based technique. On line R1, higher crustal velocities in its eastern part coincide with rocks of the Flin Flon  Namew gneiss complex. Depth to Moho is in the 4045 km range and equates to that from the reflection data, including a small crustal root below the Sask minicontinent. Along lines R2 and R3, depth to Moho varies from about 40 km up to 55 km at the north end of R2 and south end of R3. In general, variations in crustal velocity and depth to Moho do not correlate with the location and extent of geological domains; they appear to reflect the complex deformation and metamorphic history of the crustal rocks. Mantle velocities are high, ~8.2 km/s. However a limited area shows prominent velocity anisotropy, with values of 8.6 km/s along R2 and R3 and 8.1 km/s along R1. We speculate that the observed anisotropy represents an ~100-km-wide mantle suture zone resulting from the collision of Archean plates. The suture zone accommodated limited extensional deformation, associated with a counterclockwise rotation of the Superior plate, to generate the anisotropy. In this model, the lithospheric mantle of the THO internal domains and Sask craton are detached.
Geology and thermotectonic evolution of the western margin of the Trans-Hudson Orogen: evidence from the eastern sub-Athabasca basement, Saskatchewan
Authors: Annesley Irvine R , Madore Catherine , Portella Philippe
Published: July 2005

In the Cree Lake Zone of northern Saskatchewan, reworked Archean orthogneisses are overlain by a highly deformed supracrustal sequence, the Paleoproterozoic Wollaston Group. This package of rocks was deformed and metamorphosed during the ca. 1.8 Ga continentcontinent collision of the Trans-Hudson Orogen (THO), forming the Wollaston foldthrust belt that underlies the eastern Athabasca Basin. The Hudsonian structural, metamorphic, and magmatic evolution of the Wollaston fold-thrust belt in the eastern Athabasca area involved six major stages. (1) Early collisional stage, DP1 at 18601835 Ma, involved burial of Wollaston Group metasediments from surface to depths equivalent to 35vkbar (1 kbar = 100 MPa) by thrust-pile stacking or imbrication tectonics, prograde metamorphism with garnet growth and development of early leucosomes, and emplacement of ca. 1840 Ma grey granite suite. (2) Collisional stage, DP2a at 18351820 Ma, involved continued deeper burial of Wollaston Group metasediments along a prograde PTt (pressuretemperaturetime) path at depths equivalent to peak pressures of 69 kbar and approaching peak temperatures (750825 °C), mafic magma underplating in the lower crust, initiation of large-scale crustal melting, emplacement of 18351820 Ma tholeiitic to calc-alkaline intrusions, and initiation of strike-slip tectonics. (3) Oblique collisional stage, DP2b at 18201805 Ma, involved strong transpressional tectonics with NESW shearing and NWSE shortening, partitioned high-strain ductile flow, kilometre-scale fold development, initiation of exhumation, attainment of peak temperatures (750825 °C), and essentially isothermal decompression with decompressional melting and intrusion of the main pulse of leucogranites and granitic pegmatites. (4) Late oblique collisional stage, DP3 at 18051775 Ma, caused development of amphibolite-facies dextral strike-slip shear zones and retrograde movement of older shear zones. It included apparent rotation of the main shortening axis and development of accommodation features due to vertical uplift (i.e., extension). (5) Post-collisional stage, DP4 at 17751760 Ma, involved continued localized adjustments along an essentially isobaric cooling path and produced NNE-trending, sinistral, oblique-slip reverse faults with reactivation of older shear zones. (6) Late post-collisional stage, DP5, produced north- to northwest-trending sinistral faults, including the Tabbernor fault system. Extension and tectonic extrusion during DP4 and DP5 were significant and resulted in orogenic collapse and formation of the Athabasca Basin at ca. 17501680 Ma.
Tectonic evolution of the Manitoba-Saskatchewan segment of the Paleoproterozoic Trans-Hudson Orogen, Canada
Authors: Ansdell Kevin M
Published: July 2005

Time slices and schematic cross-sections that attempt to show the spatial and temporal relationship between geological entities within the ManitobaSaskatchewan segment of the Trans-Hudson Orogen and that are consistent with the available geological, geophysical, geochemical, isotopic, and geochronological data are presented. The Trans-Hudson orogenic belt developed as a result of closure of the Manikewan Ocean, which initially opened at about 2.1 Ga by rifting of a possible Neoarchean supercontinent. The oldest oceanic arc rocks indicate that subduction was ongoing by 1.92 Ga, with the development of a complex Manikewan "Ring of Fire" that lasted for the next 100 Ma. Intraoceanic accretion of arc, ocean-floor, and ocean-island rocks within the Manikewan Ocean at 1.87 Ga formed the Flin Flon  Glennie complex, which then subsequently collided with the accreted terranes along the Hearne craton margin at ca. 1.85 Ga. These rocks were then deformed and metamorphosed over the next 75 Ma during collisions with the Sask craton and the Superior craton, both of which are interpreted to have been drifting generally northwards towards the Hearne craton. The generation of arc magmas in the orogen ceased at 1.83 Ga, an indication that continental collisions were well advanced at that stage. The present arrangement and erosion level of geological entities is related to structural reorganization after the peak of regional metamorphism at ca. 1.81. The schematic time slices and sections form part of ongoing efforts to better understand the geological evolution of the Paleoproterozoic of Canada.
Introduction to special issue of Canadian Journal of Earth Sciences: The Trans-Hudson Orogen Transect of Lithoprobe
Authors: Hajnal Zoltan , Ansdell Kevin M , Ashton Ken E
Published: July 2005

Dedication: Dr. John F. Lewry (19391999; see Saskatchewan Geological Survey 1999) dedicated his career to investigations of the SaskatchewanManitoba segment of the Trans-Hudson Orogen (THO), one of the principal Paleoproterozoic orogens associated with the assembly of Laurentia. Indeed, one can make a strong case that Lithoprobe's Trans-Hudson Orogen Transect (THOT) was designed to test the tectonic models proposed by John Lewry. He delineated the distinct tectonic provinces in the western part of the THO, predicted the presence of an Archean craton trapped within the THO, and recognized and interpreted the significance of the Pelican Thrust between the juvenile Paleoproterozoic volcanic arc complex of the western Flin Flon Domain and the Archean craton, now called the Sask craton. The research published in Lewry and Stauffer (1990), and many of his ideas, provided the framework for the design of the THOT geophysical and geological studies. John Lewry was co-leader of the THOT until he passed away in 1999 after a battle with cancer. This Special Issue of the Canadian Journal of Earth Sciences is dedicated to him.
Foraging of royal albatrosses,Diomedea epomophora, from the Otago Peninsula and its relationships to fisheries
Authors: Waugh Susan , Filippi Dominique , Fukuda Akira , Suzuki Makio , Higuchi Hiroyoshi , Setiawan Alvin , Davis Lloyd
Published: July 2005

Foraging zones used by incubating royal albatrosses (Diomedea epomophora) from the Otago Peninsula and their coincidence with fisheries activities were studied with global positioning system (GPS) loggers. Birds favoured areas around the shelf break of the eastern New Zealand continental mass, with hot spots of activity that coincided with fishing zones actively exploited by commercial trawl fisheries during the study period. Birds appeared to change their behaviours with proximity to fishing events, showing reduced speed and more direct flight when at moderate distances from fishing operations (12.525 km) than at greater distances. This relationship was significant for speed only (P < 0.029). Fishing operations for hoki (Macruronus novaezelandiae) and deep-sea species were those with the most numerous associations with royal albatross foraging flights and were also the most common during the study period. Waters along shelf breaks within 100 km of the breeding colony were extremely important for royal albatrosses, 28% of GPS locations being obtained within this radius from the Otago Peninsula study. Royal albatrosses from Campbell Island, studied previously, had also fed in this area extensively. Birds spent 219 days at sea, travelling 2000 km, on average, during their foraging trips.
Lake trophic status and bioaccumulation of polychlorinated biphenyls in benthic organisms: a comparison between littoral and profundal invertebrates
Authors: Holmqvist Niklas , Stenroth Patrik , Berglund Olof , Nyström Per , Graneli Wilhelm , Larsson Per
Published: July 2005

We investigated the influence of lake trophic status on accumulation of polychlorinated biphenyls (PCBs) in littoral and profundal invertebrates from 19 lakes in southern Sweden. The PCB concentration in profundal chironomids (Chironomus sp.) was negatively correlated with lake trophy but the concentration in littoral crayfish (Pacifasticus leniusculus) was unrelated to shifting nutrient regimes. PCB concentrations in chironomids were negatively correlated, while crayfish did not correlate with lake total phosphorus. Two findings indicate that different processes determine bioaccumulation in littoral and profundal invertebrates: (i) a lack of correlation between PCB concentrations in crayfish and chironomids within lakes and (ii) some differences in congener distribution in the two species. We suggest a possible explanation in that chironomids are directly exposed to settling material from the pelagic zone, while crayfish are omnivorous and feed mainly in the littoral zone. A intensive investigation on one pond population could not reveal any individual factors, such as lipid content, size, or sex, influencing bioaccumulation of PCBs in crayfish.
Estimating catch-at-age by combining data from different sources
Authors: Hirst David , Storvik Geir , Aldrin Magne , Aanes Sondre , Huseby Ragnar Bang
Published: July 2005

Estimating the catch-at-age of commercial fish species is an important part of the quota-setting process for many different species and almost all countries with a fishing fleet. Current procedures are usually very time-consuming and somewhat ad hoc, and the estimates have no measure of uncertainty. We previously developed a method for catch-at-age of Norwegian Atlantic cod (Gadus morhua), but this only considered aged fish sampled randomly from random hauls. In most countries, the sampling scheme is not so simple. There are usually a very large number of length-only samples from which the age must be estimated using an agelength relationship, and often some or all of the age samples are collected from data that are first stratified by length. This adds considerably to the difficulties in the estimation. In this paper, we model the three different kinds of data simultaneously using a development of our earlier Bayesian hierarchical model. This enables us to obtain estimates of the catch-at-age with appropriate uncertainty and also to provide advice on how best to sample data in the future. The data types are random samples of age, length, and weight; age and weight stratified by length; and length only.
The schooling and foraging ecology of lake herring (Coregonus artedi) in Lake Opeongo, Ontario, Canada
Authors: Milne S W , Shuter B J , Sprules W G
Published: July 2005

We used a combination of suspended gill nets and hydroacoustics to investigate the schooling behaviour of lake herring (Coregonus artedi) in Lake Opeongo, Ontario, Canada. Lake herring form schools during the day but are dispersed at night and this change occurs at a light threshold of roughly 0.04 lx. Schools range in maximum linear dimension from 100 to 2300 cm with the majority under 1000 cm. The light threshold for school formation is well below that at which their principal predator, lake trout (Salvelinus namaycush), are able to detect prey. This suggests that schooling may provide advantages in addition to predator avoidance. We observed that lake herring stomachs were fuller during the day than at night, indicating that schooling herring forage more efficiently during the day than individual herring do at night. Furthermore, herring stomach fullness increased with school size, suggesting that schooling enhances foraging opportunities for individual members. We speculate that this is due either to social facilitation of feeding when herring are in the presence of conspecifics, or to corporate vigilance, or "many eyes", which allows individual fish to spend less time being alert to predators and more time feeding.
Regional, watershed, and site-specific environmental influences on fish assemblage structure and function in western Lake Superior tributaries
Authors: Brazner John C , Tanner Danny K , Detenbeck Naomi E , Batterman Sharon L , Stark Stacey L , Jagger Leslie A , Snarski Virginia M
Published: July 2005

The relative importance of regional, watershed, and in-stream environmental factors on fish assemblage structure and function was investigated in western Lake Superior tributaries. We selected 48 second- and third-order watersheds from two hydrogeomorphic regions to examine fish assemblage response to differences in forest fragmentation, watershed storage, and a number of other watershed, riparian, and in-stream habitat conditions. Although a variety of regional, fragmentation, and storage-related factors had significant influences on the fish assemblages, water temperature appeared to be the single most important environmental factor. We found lower water temperatures and troutsculpin assemblages at lower fragmentation sites and higher temperatures and minnowsuckerdarter assemblages as storage increased. Factors related to riparian shading and flow separated brook trout streams from brown trout (Salmo trutta)  rainbow trout (Oncorhynchus mykiss) streams. Functionally, fish assemblages at lower fragmentation sites were dominated by cold-water fishes that had low silt tolerance and preferred moderate current speeds, while fishes with higher silt tolerances, warmer temperature preferences, and weaker sustained swimming capabilities were most common at higher storage sites. Our results suggest that site-specific environmental conditions are highly dependent on regional- and watershed-scale characters and that a combination of these factors operates in concert to influence the structure and function of stream fish assemblages.
A model of aquaculture biodeposition for multiple estuaries and field validation at blue mussel (Mytilus edulis) culture sites in eastern Canada
Authors: Grant Jon , Cranford Peter , Hargrave Barry , Carreau Michel , Schofield Bryan , Armsworthy Shelley , Burdett-Coutts Victoria , Ibarra Diego
Published: July 2005

Development of mariculture in Canadian waters has outpaced the ability of regulators to adequately assess environmental impacts and coexistence with other resource users. In eastern Canada, suspended longline culture of blue mussels (Mytilus edulis) leads to depletion of seston and subsequent biodeposition of feces and pseudofeces. Based on the need to evaluate aquaculture effects over multiple farms, a model was developed to compare the rate of mussel egestion with the scale of culture and tidal flushing of particulate waste from estuarine waters. Egestion was calculated using a bioenergetic submodel, and tidal flushing was determined with a tidal prism method. A short-term field program of particle sensing and sediment trapping was undertaken in Tracadie Bay and Savage Harbour (Prince Edward Island) to examine model assumptions and for validation. A finite element model was used to verify tidal prism calculations. Expressing model output as sedimentation rate, predicted biodeposition in Tracadie Bay was less than that estimated from field results but within the range of estuary-wide variation. In Savage Harbour, the egestion model overestimated biodeposition, likely because culture density on leased areas was sparse. A ranking of sites based on susceptibility to culture impacts was devised for multiple culture sites.
Toxicity and bioaccumulation of tributyltin in Hyalella azteca from freshwater harbour sediments in the Great Lakes Basin, Canada
Authors: Bartlett Adrienne J , Borgmann Uwe , Dixon D George , Batchelor Suzanne P , Maguire R James
Published: July 2005

This study was designed to evaluate the risk that tributyltin (TBT) levels in harbour sediments pose to the freshwater invertebrate Hyalella azteca and to rank TBT as an environmental concern compared with inorganic metal species. Four-week toxicity tests and 2-week bioaccumulation tests were conducted with sediments collected from five harbours historically contaminated with TBT: Montreal, Kingston, Toronto, Hamilton, and Port Weller. While there was no observable effect of TBT on survival or growth of H. azteca, bioaccumulation of TBT exceeded levels expected to cause chronic toxicity in some sediments from Kingston, Montreal, and Port Weller. There was a positive relationship between TBT in H. azteca and TBT in sediments (r2 = 0.72), although TBT in field sediments was less bioavailable than in laboratory-spiked sediments. Body concentrations of arsenic, cadmium, chromium, cobalt, lead, manganese, nickel, and thallium were well below levels expected to cause toxicity in H. azteca. However, overlying water concentrations of copper and zinc approached or exceeded levels of concern in Toronto, Hamilton, and Port Weller sediments. This research suggests that levels of TBT in harbour sediments may cause chronic toxicity to H. azteca and freshwater invertebrate species of similar sensitivity and that copper and zinc also pose a risk at these sites.
Spatial distribution of brown shrimp (Farfantepenaeus aztecus) on the northwestern Gulf of Mexico shelf: effects of abundance and hypoxia
Authors: Craig J Kevin , Crowder Larry B , Henwood Tyrrell A
Published: July 2005

We used fishery-independent hydrographic and bottom trawl surveys on the northwestern Gulf of Mexico shelf from 19832000 to test for density dependence and effects of hypoxia (dissolved oxygen ≤ 2.0 mg·L1) on the spatial distribution of brown shrimp (Farfantepenaeus aztecus). Spatial distribution of shrimp was positively related to abundance on the Texas shelf but negatively related to abundance on the Louisiana shelf. Density dependence was weak, however, and may have been due to factors other than density-dependent habitat selection. Males were distributed over a broader area and further offshore than were females, though differences in spatial distribution between sexes were not large (~10%15%). Large-scale hypoxia (up to ~20 000 km2) on the Louisiana shelf occurs in regions of typically high shrimp density and results in substantial habitat loss (up to ~25% of the Louisiana shelf), with shifts in distribution and associated high densities both inshore and offshore of the hypoxic region. We discuss these results in terms of the generality of density-dependent spatial distributions in marine populations and potential consequences of habitat loss and associated shifts in distribution due to low dissolved oxygen.
Is pelagic top-down control in lakes augmented by benthic energy pathways?
Authors: Zanden M Jake Vander , Essington Timothy E , Vadeboncoeur Yvonne
Published: July 2005

Modern food web studies are typically conducted from a trophic dynamic perspective that focuses on combined roles of top-down and bottom-up forces in regulating food web structure. Recognition of spatial food web subsidies in diverse ecosystems highlights the importance of energy flow as a foundation for understanding trophic dynamics. Here, we consider how different energy flow configurations might affect trophic dynamics in north-temperate lakes. A literature review revealed that littoral piscivores exert top-down control on prey fishes. In contrast, analysis of littoral predator diets indicated extensive omnivory and heavy reliance on zoobenthic prey. We explored this uncoupling between trophic dynamics (piscivores regulate prey fish) and energy flow (zoobenthos in piscivore diets) using a biomass dynamic model. This model compared top-down impacts of a piscivore on prey fishes under two scenarios: consumption of prey fish only and consumption of prey fish plus zoobenthos. The model predicted that elimination of zoobenthivory leads to a 50% reduction in piscivore standing stock and concomitant 2.5-fold increase in prey fish abundance (i.e., zoobenthivory plays a key role in mediating pelagic top-down control). These results highlight the role of benthicpelagic linkages in regulating trophic dynamics and underscore the value of whole-ecosystem approaches to the study of food webs.
Costs and benefits of Daphnia defense against Chaoborus in nature
Authors: Boeing Wiebke J , Wissel Björn , Ramcharan Charles W
Published: July 2005

To estimate costs and benefits of antipredator defenses in the ChaoborusDaphnia system, we employed lake enclosures wherein controls (C) had no predators, the predation (P) treatment had freely swimming Chaoborus, and the kairomone (K) treatment predators were sequestered in a mesh tube apart from the Daphnia. Population growth (r) of two Daphnia pulex clones, one responsive (RC) and the other nonresponsive (NRC) to Chaoborus kairomone, was estimated for each predator treatment. Cost of defense was calculated as r(C,RC)  r(K,RC). Benefit was calculated as r(P,RC)  r(P,NRC). Antipredator defenses of Daphnia towards Chaoborus kairomone led to a 32% reduction in population growth in nature. The benefit of the defense, however, was a short-term 68% enhanced population growth by a responsive over a nonresponsive clone in the presence of the actual predation threat. The benefit of the defense exceeded the cost, but cost was nevertheless substantial. Our results verify that the in situ effects of Chaoborus on Daphnia involve direct and indirect impacts.
Periphyton, water quality, and land use at multiple spatial scales in Alberta rivers
Authors: Carr Geneviève M , Chambers Patricia A , Morin Antoine
Published: July 2005

The ability of land use to replace water quality variables in predictive models of periphyton chlorophyll a was tested with a 21-year data set for Alberta rivers. Nutrients (total dissolved P and NO2 + NO3) explained 23%24% of the variability in seasonal chlorophyll a, whereas land use (human population density) explained 25%28% of the variability. The best models included the combination of total dissolved P and population density, explaining 32%34% of periphyton chlorophyll a variability. However, analysis of variance of chlorophyll a by ecoregions and ecozones explained about as much variability (28%30%), and the inclusion of an ecoregion term into the regression models showed a diminished importance of land use as a predictor of chlorophyll a, with best models based on the combination of nutrients and ecoregion and explaining up to 43%44% of periphyton chlorophyll a variability. Within ecoregions, land use was sometimes a good surrogate for nutrient data in predicting chlorophyll a concentrations. Overall, land use is a suitable surrogate for nutrients in regression models for chlorophyll a, but its inclusion in general models may reflect regional differences in nutrientchlorophyll relationships rather than true land use effects on chlorophyll a.
Variation of Y-chromosome DNA markers in Chinook salmon (Oncorhynchus tshawytscha) populations
Authors: Devlin R H , Park L , Sakhrani D M , Baker J D , Marshall A R , LaHood E , Kolesar S E , Mayo M R , Biagi C A , Uh M
Published: July 2005

Two Y-chromosome DNA markers (a repetitive sequence, OtY1, and a single-copy marker, GH-Y) tightly linked to the sex-determination locus have been examined for their association with sexual development among 55 populations of Chinook salmon (Oncorhynchus tshawytscha) from the Yukon, British Columbia, Washington, Oregon, and Idaho. Normal linkage has been observed in 96.7% of 2478 individuals examined. Only five males (0.44%) were found lacking both markers (none from Canadian systems), and 14 females (1.04%) from US populations and two females (0.15%) from Canadian populations were found to possess both markers. Variants identified included weakly amplifying alleles for GH-Y and OtY1 and structural variants identified by Southern-blot analysis. The frequency of variants in males was more than 2-fold that in females, and males deficient in GH-Y were more common (3.6%) than males deficient in the repetitive OtY1 sequence (0.7%). Some individuals (of both sexes) possessed fewer copies of the OtY1 repeat than normal males, revealing molecular dynamics that alter Y-chromosome structure within and among populations. A population (Hanford Reach) previously reported as having a high incidence of females possessing the OtY1 marker, and suspected of being sex-reversed, was found to have normal sex-marker genotypes in the present study.
Behavior and recruitment success in fish larvae: variation with growth rate and the batch effect
Authors: Fuiman Lee A , Cowan, Jr. James H , Smith Michael E , O'Neal Jonathan P
Published: July 2005

Predation-mortality risk for red drum (Sciaenops ocellatus) larvae does not appear to be related to their growth rate, but important differences in behavioral performance occur between batches of larvae. This conclusion is based upon field-enclosure and laboratory experiments that assessed the degree to which predation-mortality rates and behavioral survival skills vary with growth rate. In field enclosures, populations composed of 15 fast-growing larvae and 15 slow-growing larvae of a comparable size were exposed to a predatory fish. Growth rate did not affect predation rate. In the laboratory we measured 11 survival skills on 100 larvae of a common size from 10 batches of eggs. For each batch, behavioral performance of fast-growing larvae was compared with that of slow-growing larvae. Growth rate did not affect performance in 10 of the 11 survival skills, but behavioral performance varied among treatment groups (growth rate × batch), with higher performance in most survival skills for some treatment groups and consistently poorer performance for other groups. This coordinated pattern of behavioral performance forecasts differential survival among batches. The variation among batches may be related to timing of spawning within the reproductive season of this serially spawning species.
Interacting effects of behavior and oceanography on growth in salmonids with examples for coho salmon (Oncorhynchus kisutch)
Authors: Snover Melissa L , Watters George M , Mangel Marc
Published: July 2005

Positive and negative relationships between pre- and post-smolt growth rates in salmonids have been observed, but the mechanisms underlying these relationships are not understood. We hypothesize that growth at sea is controlled by interactions between behavior and ocean conditions and that no one relationship is correct. We present a growth model with habitat-specific rates of anabolism that allow resource acquisition to vary in response to the behaviorenvironment interaction. Our model predicts positive relationships between pre- and post-smolt growth rates when ocean resources have clumped, defensible distributions under which conditions that aggressive behaviors facilitate increased access to those resources. Negative relationships are predicted when resources are dispersed and aggressive behaviors are ineffective. We present data relating pre- and post-smolt growth rates for more than 15 stocks of coho salmon (Oncorhynchus kisutch). These data indicate that shortly after out-migrating, aggressive behaviors are not effective for securing resources in the ocean (i.e., there are negative or no relationships between pre- and post-smolt growth rates). As coho spend more time at sea, however, variability in environmental conditions can elicit a variety of growth responses.
Ecology of the Lake Huron fish community, 1970-1999
Authors: Dobiesz Norine E , McLeish David A , Eshenroder Randy L , Bence James R , Mohr Lloyd C , Ebener Mark P , Nalepa Thomas F , Woldt Aaron P , Johnson James E , Argyle Ray L , Makarewicz Joseph C
Published: July 2005

We review the status of the Lake Huron fish community between 1970 and 1999 and explore the effects of key stressors. Offshore waters changed little in terms of nutrient enrichment, while phosphorus levels declined in inner Saginaw Bay. Introduced mussels (Dreissena spp.) proliferated and may have caused a decline in Diporeia spp. This introduction could have caused a decline in lake whitefish (Coregonus clupeaformis) growth and condition, with serious repercussions for commercial fisheries. Bythotrephes, an exotic predatory cladoceran, and other new exotics may be influencing the fish community. Sea lampreys (Petromyzon marinus) remained prevalent, but intensive control efforts on the St. Mary's River may reduce their predation on salmonines. Overfishing was less of a problem than in the past, although fishing continued to reduce the amount of lake trout (Salvelinus namaycush) spawning biomass resulting from hatchery-reared fish planted to rehabilitate this species. Massive stocking programs have increased the abundance of top predators, but lake trout were rehabilitated in only one area. Successful lake trout rehabilitation may require lower densities of introduced pelagic prey fish than were seen in the 1990s, along with continued stocking of hatchery-reared lake trout and control of sea lamprey. Such reductions in prey fish could limit Pacific salmon (Oncorhynchus spp.) fisheries.
Aggression and feeding of hatchery-reared and naturally reared steelhead (Oncorhynchus mykiss) fry in a laboratory flume and a comparison with observations in natural streams
Authors: Riley Stephen C , Tatara Christopher P , Scheurer Julie A
Published: July 2005

We quantified the aggression and feeding of naturally reared steelhead (Oncorhynchus mykiss) fry stocked into a laboratory flume with naturally reared fry or hatchery-reared fry from conventional and enriched rearing environments at three densities in the presence and absence of predators, and compared the aggression and feeding observed in the flume to that observed in two streams. Steelhead fry attack rate increased with density and was reduced in the presence of predators, but was not affected by rearing treatment. Threat rate appeared to increase with density and was significantly affected by rearing treatment combination, but was not significantly affected by predator presence. Feeding rate was not affected by density or rearing treatment, but was reduced in the presence of predators. The rate of aggression by steelhead fry in two streams was lower than that observed in the laboratory and did not increase with density. Rates of aggression and feeding of hatchery-reared and wild steelhead fry were not significantly different in the streams. Overall, we found no evidence that hatchery rearing environments caused higher aggression in steelhead fry. Laboratory observations of salmonid aggression, particularly at high density, may not reflect aggression levels in the wild.
Oceanographic connectivity among marine protected areas on the north coast of British Columbia, Canada
Authors: Robinson Clifford LK , Morrison John , Foreman Michael GG
Published: July 2005

The main objective of our study was to use a three-dimensional oceanographic simulation model to understand connectivity among the proposed Gwaii Haanas National Marine Conservation Area (GHNMCA) and 10 other proposed or existing marine protected areas (MPAs) on the north Pacific coast of Canada. The simulations were conducted using passive particles placed at three depths and vertically migrating particles for 30 or 90 days in late winter. Simulated surface particle dispersion was found to be consistent with winter ocean current observations made from analysis of satellite imagery, current mooring, and drifter data. The GHNMCA would contribute to a network of MPAs because it supplies and receives particles from other MPAs in northern British Columbia. Model simulations also indicate that the greatest source of particles to GHNMCA originate from 30-m and not 2-m flows. Finally, the simulated mean daily dispersal rate of 2.0 km·day1 would allow fish and invertebrates to self-seed northern portions of the GHNMCA in winter. Together, the GHNMCA and other MPAs appear to contribute a large percentage of particles to non-MPA regions in northern Hecate Strait, which may be considered a particle sink in winter.
Identical thermodynamical processes and entropy
Authors: Anacleto Joaquim
Published: July 2005

Starting from the concept of identical thermodynamical processes, we treat invariance under interchange of identical processes as a symmetry. We show the conservation of entropy in reversible processes to be intimately related to this symmetry. PACS Nos.: 44.60, 65.50
A simple melting theory applied to alkali halide, alkaline-earth chalcogenide, and alkali chalco-genide compounds
Authors: Liu Quan , Chen Li-rong
Published: July 2005

A useful and simple method for studying the melting temperature Tm of ion compounds has been developed by using analyses originally due to diffusional force theory, incorporating Pandey's formulation and Harrison's potential function. The calculated values of Tm for a wide range of compounds of types IAVII (alkali halide), IIAVI (alkaline-earth chalcogenide), and IAVI (alkali chalcogenide) are found to agree fairly well with experimental values for Tm and to be superior to results from previous approaches involving similar methods. PACS Nos.: 64.70.Dv, 67.80.Gb
The effect of Hall current on magnetohydrodynamic flow and heat transfer forBingham fluids in a rectangular duct
Authors: Sayed-Ahmed Mohamed Eissa , Attia Hazem Ali
Published: July 2005

Laminar fully developed magnetohydrodynamic flow and heat transfer through a rectangular duct are investigated for the case of a viscous incompressible electrically conducting Bingham fluid. A constant pressure gradient and an external uniform magnetic field are applied. The Hall effect is taken into consideration. As thermal boundary conditions, constant wall heat flux is assumed axially and constant wall temperature is assumed peripherally, while the apparent viscosity is assumed to vary with the temperature. The governing momentum and energy equations are solved numerically with finite-difference approximations. The velocity, the temperature, the average friction factor, and the Nusselt number are computed for various values of the physical parameters.PACS Nos.: 44.05.te, 44.10.ti, 44.15.+a, 44.20.+b, 44.35.+c, 47.11.tj
Why the cavity-mode method for deriving Planck's law is flawed
Authors: Irons F E
Published: July 2005

The cavity-mode method for deriving Planck's law (the method pioneered by Lord Rayleigh in 1900 for the regime hv << kT) is known to lack internal consistency. Past attempts at bypassing the inconsistency have proceeded by postulating a novel type of interaction between radiation and matter, one which contrasts with the type of interaction to be found in the widely accepted, detailed balancing method for deriving Planck's law (the method pioneered by Planck and Einstein). The paper examines this issue and finds that the novel interaction is an invention without supportive evidence, being just the type of interaction needed to bypass the inconsistency. The conclusion is that the inconsistency remains real and the cavity-mode method for deriving Planck's law remains flawed.PACS Nos.: 01.55.+b, 42.50.p
Collisions of electrons with atomic oxygen: current status
Authors: Johnson P V , McConkey J W , Tayal S S , Kanik I
Published: July 2005

In 1990, two significant reviews of electronatomic-oxygen collision processes were published. Since that time, a large volume of both experimental and theoretical research into these processes has occurred. These data are reviewed and recommendations regarding existing data sets and future research in this area are made. Attention is given to the challenges associated with handling atomic oxygen in terms of both experiment and theory. PACS Nos.: 34.80.Bm, 34.80.Dp
PARALLEL TRANSPORT ON NON-ABELIAN FLUX TUBES
Authors: LAHIRI AMITABHA
Published: July 2005

We propose a way of unambiguously parallel transporting fields on non-Abelian flux tubes, or strings, by means of two gauge fields. One gauge field transports along the tube, while the other transports normal to the tube. Ambiguity is removed by imposing an integrability condition on the pair of fields. The construction leads to a gauge theory of mathematical objects known as Lie 2-groups, which are known to result also from the parallel transport of the flux tubes themselves. The integrability condition is also shown to be equivalent to the assumption that parallel transport along nearby string configurations are equal up to arbitrary gauge transformations. Attempts to implement this condition in a field theory leads to effective actions for two-form fields.
A NEW ALGEBRAIC APPROACH TO PERTURBATION THEORY
Authors: GÖNÜL B. , ÇELİK N. , OLĞAR E.
Published: July 2005

An algebraic nonperturbative approach is proposed for the analytical treatment of Schrödinger equations with a potential that can be expressed in terms of an exactly solvable piece with an additional potential. Avoiding disadvantages of standard approaches, new handy recursion formulas with the same simple form both for ground and excited states have been obtained. As an illustration the procedure, well adapted to the use of computer algebra, is successfully applied to quartic anharmonic oscillators by means of very simple algebraic manipulations. The trend of the exact values of the energies is rather well reproduced for a large range of values of the coupling constant (g = 0.001–10000).
DARK ENERGY IN AN AXION MODEL WITH EXPLICIT Z(N) SYMMETRY BREAKING
Authors: JAIN PANKAJ
Published: July 2005

We point out that a well-known axion model with an explicit Z(N) symmetry breaking term predicts both dark energy and cold dark matter. We estimate the parameters of this model which fit the observed densities of the dark components of the universe. We find that the parameters do not conflict with any observations.
ENERGY AND MOMENTUM DISTRIBUTIONS OF THE MAGNETIC SOLUTION TO (2+1) EINSTEIN–MAXWELL GRAVITY
Authors: GRAMMENOS TH.
Published: July 2005

We use Møller's energy–momentum complex in order to explicitly evaluate the energy and momentum density distributions associated with the three-dimensional magnetic solution to the Einstein–Maxwell equations. The magnetic spacetime under consideration is a one-parametric solution describing the distribution of a radial magnetic field in a three-dimensional AdS background, and representing the superposition of the magnetic field with a 2+1 Einstein static gravitational field.
HAWKING RADIATION VIA TUNNELING FROM KERR BLACK HOLES
Authors: ZHANG JINGYI , ZHAO ZHENG
Published: July 2005

In this paper, Parikh's recent work, which treats Hawking radiation as a tunneling process in a spherically symmetric spacetime, is extended to the stationary axisymmetric Kerr spacetime. A generalized Painleve coordinate system (Painleve–Kerr coordinates) is introduced. The new coordinates are well-behaved at the event horizon. Constant-time slices are just flat Euclidean space in radial and satisfy Landau's condition of clock synchronization. The tunneling process across the Kerr black hole event horizon is investigated and the correctd radiation spectrum is obtained. The result is consistent with an underlying unitary theory.
ON AUXILIARY FIELDS IN BF THEORIES
Authors: GHAFFOR D. , TAHIRI M.
Published: July 2005

We discuss the structure of auxiliary fields for non-Abelian BF theories in arbitrary dimensions. By modifying the classical BRST operator, we build the on-shell invariant complete quantum action. Therefore, we introduce the auxiliary fields which close the BRST algebra and lead to the invariant extension of the classical action.
NILPOTENT SYMMETRIES FOR A FREE RELATIVISTIC PARTICLE IN AUGMENTED SUPERFIELD FORMALISM
Authors: MALIK R. P.
Published: July 2005

In the framework of the augmented superfield formalism, the local, covariant, continuous and off-shell (as well as on-shell) nilpotent (anti-)BRST symmetry transformations are derived for a (0+1)-dimensional free scalar relativistic particle that provides a prototype physical example for the more general reparametrization invariant string- and gravitational theories. The trajectory (i.e. the world-line) of the free particle, parametrized by a monotonically increasing evolution parameter τ, is embedded in a D-dimensional flat Minkowski target manifold. This one-dimensional system is considered on a (1+2)-dimensional supermanifold parametrized by an even element τ and a couple of odd elements (θ and [Formula: see text]) of a Grassmannian algebra. The horizontality condition and the invariance of the conserved (super)charges on the (super)manifolds play very crucial roles in the above derivations of the nilpotent symmetries. The geometrical interpretations for the nilpotent (anti-)BRST charges are provided in the framework of augmented superfield approach.
THE QUANTUM TRAJECTORY APPROACH TO GEOMETRIC PHASE FOR OPEN SYSTEMS
Authors: CAROLLO ANGELO
Published: July 2005

The quantum jump method for the calculation of geometric phase is reviewed. This is an operational method to associate a geometric phase to the evolution of a quantum system subjected to decoherence in an open system. The method is general and can be applied to many different physical systems, within the Markovian approximation. As examples, two main source of decoherence are considered: dephasing and spontaneous decay. It is shown that the geometric phase is to very large extent insensitive to the former, i.e. it is independent of the number of jumps determined by the dephasing operator.
SAVVIDY VACUUM IN SU(2) YANG–MILLS THEORY
Authors: KAY DANIEL , KUMAR A. , PARTHASARATHY R.
Published: July 2005

The one-loop effective energy density of a pure SU (2) Yang–Mills theory in the Savvidy background is reconsidered. The stable and the unstable modes are identified. The stable modes are treated in the quadratic approximation. For the unstable modes, the full expansion including the cubic and the quartic terms in the fluctuations is used. The functional integral for the unstable modes is evaluated and added to the result for the stable modes. The resulting energy density coincides with the real part in the quadratic approximation of earlier studies and there is now no imaginary part.
ON THE DEGENERACIES OF THE MASS-SQUARED DIFFERENCES FOR THREE-NEUTRINO OSCILLATIONS
Authors: LATIMER D. C. , ERNST D. J.
Published: July 2005

Using an algebraic formulation, we explore two well-known degeneracies involving the mass-squared differences for three-neutrino oscillations assuming CP symmetry is conserved. For vacuum oscillation, we derive the expression for the mixing angles that permit invariance under the interchange of two mass-squared differences. This symmetry is most easily expressed in terms of an ascending mass order. This can be used to reduce the parameter space by one half in the absence of the MSW effect. For oscillations in matter, we derive within our formalism the known approximate degeneracy between the standard and inverted mass hierarchies in the limit of vanishing θ13. This is done with a mass ordering that permits the map Δ31↦-Δ31. Our techniques allow us to translate mixing angles in this mass order convention into their values for the ascending order convention. Using this dictionary, we demonstrate that the vacuum symmetry and the approximate symmetry invoked for oscillations in matter are distinctly different.
GLOBAL FITS TO THE CABIBBO–KOBAYASHI–MASKAWA MATRIX: UNITARITY CONDITION METHOD VERSUS STANDARD UNITARITY TRIANGLES APPROACH
Authors: DITA PETRE
Published: July 2005

The aim of the paper is to make a comparison between the unitarity condition method and the standard version of the unitarity triangle approach by using as parameters four independent moduli |Uij|. This choice is motivated by the measurability property and leads to a simple criterion for the separation of unistochastic matrices from the double stochastic ones, whose fulfillment is the key point of any global fit for the CKM entries. In our formulation both the methods are exact, do not depend on any assumption as the smallness of some parameter and both can be used to global fits in the quark and fermion sectors. Monte Carlo simulations show that the separation criterion puts very strong conditions requiring a fine tuning of all the CKM matrix elements.
BULK VISCOSITY EFFECTS ON THE EARLY UNIVERSE STABILITY
Authors: CARLEVARO NAKIA , MONTANI GIOVANNI
Published: July 2005

We present a discussion of the effects induced by the bulk viscosity on the very early Universe stability. The matter filling the cosmological (isotropic and homogeneous) background is described by a viscous fluid having an ultrarelativistic equation of state and whose viscosity coefficient is related to the energy density via a power-law of the form ζ = ζ0 ρν. The analytic expression of the density contrast (obtained for ν = 1/2) shows that, for small values of the constant ζ0, its behavior is not significantly different from the non-viscous one derived by Lifshitz. But as soon as ζ0 overcomes a critical value, the growth of the density contrast is suppressed forward in time by the viscosity and the stability of the Universe is favored in the expanding picture. On the other hand, in such a regime, the asymptotic approach to the initial singularity (taken at t = 0) is deeply modified by the apparency of significant viscosity in the primordial thermal bath, i.e. the isotropic and homogeneous Universe admits an unstable collapsing picture. In our model this feature also regards scalar perturbations while in the non-viscous case it appears only for tensor modes.