bluuebunny/crossref_metadata_2025 huggingface dataset:
Five new genera in the new family Pseudeurotiaceae
Authors: Malloch D. , Cain R. F.
Published: September 2008

The Pseudeurotiaceae, a new family of cleistothecial Ascomycetes, is established. Members of this family are characterized by nonostiolate ascocarps which are frequently dark in color, irregularly disposed asci, and hyaline or brown ascospores which lack germ pores. The conidia are usually borne on simple phialides or sympodulae. Cryptendoxyla, Hapsidospora, Leuconeurospora, Mycoarachis, and Nigrosabulum are described as new genera and included in the Pseudeurotiaceae. A key to the genera of the Pseudeurotiaceae is also given and some comments are offered on the previously established genera.
Herbaceous wetland vegetation in the aspen grove and grassland regions of Saskatchewan
Authors: Walker B. H. , Coupland R. T.
Published: September 2008

Wetland vegetation in the aspen grove and grassland regions of Saskatchewan was examined with respect to vegetation types and environmental control of species distribution. Species frequency and presence and a number of environmental gradients were measured in 246 stands. Association analysis of the vegetation data resulted in 27 vegetation groups, distinct on the basis of species present. Owing to overriding effects of disturbance, nine of these groups show close similarities to one or more of the others on the basis of dominant species. Water regime, salinity, and disturbance are the three major gradients influencing species distribution. Combinations of these three gradients comprise 23 environmental categories into which the vegetation groups fall. The occurrence of different vegetation groups in the same habitat type is due partly to environmental factors other than those considered in this study and partly to succession.
Induction of pigmentation of Thielaviopsis basicola and other fungi by a bacterium isolated from soil
Authors: Patrick Z. A. , Schlifer Maury
Published: September 2008

A blue-pigmented bacterium was isolated from soil and as a contaminant in cultures of Thielaviopsis basicola isolated from diseased tobacco roots. When the bacterium, a species of Pseudomonas, was grown in culture in association with T. basicola, a blue pigmentation was observed in the fungus. In addition to pigmentation of hyphae and conidia, other deleterious effects were induced in the fungus, including cytoplasmic granulation, vacuolation, contraction of cellular contents, reduced growth, and subsequent death of the affected cells. Other fungi, including Fusarium oxysporum f. sp. lycopersici, Botrytis convoluta, Rhizopus sp., and Mucor sp., were similarly affected. Hyphal pigmentation and other effects were observed only when viable bacteria were growing in intimate contact with the fungus mycelium. The pigment-inducing substance was not secreted into the culture media and was not obtained from lysed bacteria. Pigmentation and the other characteristic effects on T. basicola were not observed when the fungus and bacteria were added to soil. Similarly no significant reduction in severity of black root rot of tobacco seedlings was obtained when the blue bacteria were added to T. basicola infested soil.
Studies on bud development in the rhizome of Agropyron repens. 1. The influence of temperature, light intensity, and bud position on the pattern of development
Authors: McIntyre Gordon I.
Published: September 2008

When plants of Agropyron repens L. Beauv. are grown at a low nitrogen level, decapitation of the rhizomes releases the lateral buds from inhibition and results in a well-marked polarity of bud development. This polarity is typically characterized by the restriction of shoot development to the bud nearest the apical end of the rhizome, the production of rhizomes from buds at a greater distance from the apex, and a tendency for the buds at the basal nodes to remain inhibited.It was shown that this pattern of bud development is readily affected by environmental conditions. Increasing the temperature from 15° to 25 °C caused a marked increase in shoot formation at the expense of rhizome production and a small increase in the number of dormant buds. Reducing the light intensity had a similar but much more pronounced effect. The position of the buds in relation to the cut end of the rhizome was relatively less important as a morphogenetic factor than their position on the intact plant.As a working hypothesis, based on previous results, it is suggested that a gradient in the C/N ratio might account for the observed polarity of bud development.
Changes in proteins, free amino acids, and amides accompanying imbibition and vernalization of wheat grains
Authors: Jones Rogers A. D. , Weinberger Pearl
Published: September 2008

Vernalization has a negligible effect on the total protein content of spring and winter grains. However, large increases in the total alcohol-soluble amino acid and amide fractions were observed. The proportional distribution of amino acids and amides varied both between grain parts and between spring and winter wheats.Three bases of computing the amino acid and amide data were used in all cases, i.e. protein, dry weight, or grain part. Apparent differences in the magnitude of change with vernalization were dependent upon the base from which the data was calculated. This study indicates that data expressed on a dry weight basis alone may lead to an erroneous picture of metabolic change.
Ascocarp development of Eutypella parasitica
Authors: Lachance Denis , Kuntz James E.
Published: September 2008

Perithecial initials of Eutypella parasitica were found during the spring in bark phellem of cankered sugar maples. These initials were commonly intermingled with mature perithecia probably produced in the current year. One or several ascogonial coils appeared in these initials, but no trichogyne-like hyphae were seen in the archicarp. Asci developed rapidly from croziers formed on ascogenous hyphae and enlarged almost to their mature size before the diploid fusion nucleus divided to form the eight ascospores. The perithecium of E. parasitica has a Xylaria-type centrum as defined by Luttrell in 1951.
Barbiturate-induced α-amylase synthesis in barley endosperm
Authors: White G. A.
Published: September 2008

Phenobarbital has been found to promote the synthesis and secretion of α-amylase by embryoless barley seeds. Optimal activity was observed at a phenobarbital concentration of 1.0 mM, which promoted 39–82% (average, 57%) as much α-amylase formation as did saturating concentrations of gibberellic acid (GA3). Barley half-seeds incubated with 0.1 mM phenobarbital secreted as much protein as did those treated with 1.0 μM GA3. The kinetics of release of α-amylase from half-seeds incubated with either phenobarbital or GA3 appeared identical. Phenobarbital likely induces a de novo synthesis of α-amylase since the increase in enzyme activity was almost totally blocked by cycloheximide and 6-methylpurine. Besides phenobarbital, only cyclobarbital, amytal, hexobarbital, and thiopental showed activity among a large number of barbiturates and related drugs which were tested. In the phenobarbital molecule, the carbonyl oxygen at position 2 and the hydrogen on the nitrogen at position 3 of the barbituric acid ring are absolute requirements for activity since both 2-desoxyphenobarbital and methylphenobarbital elicited no response. Substitution of the phenyl moiety of phenobarbital with any group other than a cyclohexenyl (cyclobarbital) or an isoamyl (amytal) gave complete inactivity. Some possible mechanisms for the mode of action of phenobarbital in the barley endosperm system are discussed with particular reference to what is currently known regarding the inductive action of this barbiturate in mammalian liver.
Elongation of wheat leaves in response to cyanide in the presence and absence of iron
Authors: Israelstam G. F.
Published: September 2008

Wheat seedlings were grown in media with and without iron. Cyanide was found to inhibit leaf elongation to a greater extent in those plants grown in a nutrient solution containing iron than plants grown in an iron-free solution. A number of possibilities which could account for this anomaly are suggested.
Studies on Himalayan yeasts and molds. IV. Several asporogenous yeasts including two new taxa of Cryptococcus
Authors: Goto Shoji , Sugiyama Junta
Published: September 2008

Thirteen strains referred to six asporogenous yeast species were isolated from soil, dung, and forest humus samples collected in Bhutan. The following species, including two new taxa of Cryptococcus, were recovered: Cryptococcus albidus,Cryptococcus bhutanensis sp. nov., Cryptococcus diffluens,Cryptococcus himalayensis sp. nov., Torulopsis Candida, and Rhodotorula glutinis.
Presence of a fungal inhibitor in the pericarps of Acer saccharum fruits
Authors: Webb D. P. , Agnihotri V. P.
Published: September 2008

The present data suggest that the pericarps of Acer saccharum contain a water-soluble fungal inhibitor that protects the fruit from fungal pathogens. Aqueous pericarp extracts effectively inhibited mycelial growth of several pathogenic soil fungi, particularly species of Pythium and Rhizoctonia. The extract also controlled damping-off of Pinus resinosa seedlings and inhibited microbial respiration in nursery soil. Even at relatively low concentrations (0.003% w/v), the extract lysed germ tubes and induced morphological abnormalities. Bioassays of chromatographically partitioned extracts indicated that four major compounds were present, one capable of markedly inhibiting germination of sporangia of Pythium irregulare. Two-dimensional paper chromatography of heat-treated extracts indicated that three additional spots were present. One spot showed characteristics of gallic acid; this suggests that the inhibitor is a gallotannin.
Influence of light intensity and photoperiod on frost-hardiness development in Douglas-fir seedlings
Authors: Driessche R. van den
Published: September 2008

Effect of light intensity and photoperiod on frost-hardiness development in 2-year-old Douglas-fir seedlings was studied using an electrical conductivity method to assess stem hardiness. Hardiness increased with light intensity to 1000 ft-c at 7.5 °C, under both 8-h and 16-h photoperiods, after about 8 weeks. This response suggested photosynthesis was necessary for rapid hardening, as also did the more rapid hardening obtained under continuous light at 40 ft-c, compared with 8-h photoperiods of the same intensity. By contrast, short photoperiods enhanced the rate of hardening at a light intensity of 3000 ft-c and 500 ft-c (after 7 weeks), compared with long photoperiods. After 7 weeks plants under short photoperiods with supplementary red light hardened like plants under long photoperiods, but after 10 weeks this effect of red light was no longer apparent. Far-red light did not produce any effect. Evidently a certain amount of photosynthesis must be carried out by Douglas-fir seedlings for rapid development of hardiness, but, with sufficient light for this to occur, short photoperiods hasten hardening.
Nitrogenous substances associated with differential cone production responses of Douglas fir to ammonium and nitrate fertilization
Authors: Ebell L. F. , McMullan Eleanor E.
Published: September 2008

Nitrogenous substances were analyzed from 6-week-old foliage of 13-year-old Douglas fir, treated at vegetative bud break with 200 to 1600 lb/ac of ammonium or nitrate nitrogen. Increasing rates of nitrate nitrogen elevated seed cone production the next year by 2 to 7 times, whereas ammonium nitrogen produced no responses. Total nitrogen increases and shoot growth were similar from the two forms of nitrogen. Increases in total free amino acids with increasing rates of nitrate treatment were double those from ammonium, but size of the free amino acid pool appeared unrelated to seed cone production. Amino acid patterns, and traces of several guanidino compounds, from ammonium treatments did not vary appreciably from those of the untreated control. Most of the increase in total nitrogen from ammonium treatment was incorporated as protein, but electrophoretic patterns did not vary qualitatively with the form of nitrogen supplied. Large accumulations of basic amino acids, notably arginine, and guanidino substances resulted from nitrate treatment. This arginine-type metabolism appeared quantitatively associated with seed cone production.
Low-temperature requirements for ascospore germination and growth of Hypoxylon diathrauston
Authors: Ouellette G. B. , Ward E. W. B.
Published: September 2008

Ascospores of Hypoxylon diathrauston Rehm germinated only at freezing temperatures or required pretreatments at −3 °C to enable them to germinate at 12 °C. They required from 10 to 30 days to germinate in our experiments. They germinated by two, but occasionally one, three, and even four, germ tubes growing through pores in the relatively thick inner wall at each end of the slit after its enlargement. Cultures grew at 0 °C with an optimum at 12–15 °C, and a maximum between 18 and 21 °C.
Changes in the cotyledons of Cucurbita maxima during germination. I. General characteristics
Authors: Lott John N. A.
Published: September 2008

Various structural and physiological changes in squash cotyledons were followed as a function of germination time. Temperature, to which squash plants are very sensitive, was kept constant at 31 °C but light conditions were varied.In light-germinated plants (16 h light/day) the cotyledons changed from storage organs to greatly enlarged photosynthetic leaves, within 5 days. Incorporation of major amounts of thymidine-2-14C throughout the cotyledons occurred only during the enlargement phase.Dark-germinated plants, in which the cotyledons enlarged very little, produced a long, stout hypocotyl. No major incorporation of thymidine-2-14C into the cotyledons occurred, suggesting that little cell division occurs in the cotyledons of dark-germinated squash plants.Fresh- and dry-weight changes in the cotyledons were consistent with the changes in morphology of light- and dark-germinated plants. The cotyledons of plants which were dark-germinated for 6 days and then placed in 16 h light per day did not reach the fresh weight per cotyledon or dry weight per cotyledon level attained by cotyledons from plants germinated, from the beginning in 16 h light per day.
Changes in the cotyledons of Cucurbita maxima during germination. II. Development of mitochondrial function
Authors: Lott John N. A. , Castelfranco Paul
Published: September 2008

Mitochondrial respiration in squash cotyledons was followed during germination. Cytochrome oxidase and succinoxidase activities were determined in isolated mitochondrial preparations; tissue localizations of cytochrome oxidase and succinic dehydrogenase were determined histochemically in fresh tissue slices. The respiratory activities differed in light- and dark-germinated plants. In light-grown plants, the respiratory activity reached a peak at 3 days, when the root and the stem were actively growing, and then declined markedly as the tissue became photosynthetic. During the peak, the respiratory activity was present in all the cotyledon tissues; in the foliaceous cotyledons the respiratory activity was localized in the veins. In dark-grown plants the peak of respiratory activity extended over several days and the respiratory rate remained high throughout the cotyledon's life. This broad peak of activity may be related to the mobilization of storage materials for the growth of the embryo axis. In dark-germinated plants, the respiratory activity was widespread throughout the cotyledonary tissues during the peak of activity; the activity became vein localized by 8 days. Electron microscopic studies of cotyledon tissues showed the presence of many mitochondrial profiles in the veinlet regions.
Interspecific hybridization between Betula cordifolia and B. populifolia at Valcartier, Quebec
Authors: Guerriero Alexandra Glashan , Grant W. F. , Brittain W. H.
Published: September 2008

A cytological and morphological study using hybrid indices, pictorialized scatter diagrams, and polygonal graphs has been carried out on a collection of Betula cordifolia Regel, B. populijolia Marsh., and some hybrids of these two species × B. caerulea Blanch. (B. caerulea Blanch, and B. caerulea-grandis Blanch.). A somatic chromosome number of 28 was determined for plants of all accession numbers of these taxa. Measurements of morphological characters were also made on plants of B. papyrifera Marsh. Hybrid index values, a pictorialized scatter diagram, and polygons showed that plants of B. caerulea and B. caerulea-grandis were hybrids and (or) introgressants between B. cordifolia and B. populifolia, confirming the study by Brittain and Grant on the Grand Manan Island population in which the name × B. caerulea Blanchard was given to all individuals resulting from hybridization or backcrosses between these two taxa. Significant interlocality (Valcartier and Grand Manan Island) differences were noted for measurements of some characters: for B. papyrifera, the number of pairs of lateral veins in the leaf and guard cell length; for B. cordifolia, achene length, pairs of lateral veins in leaf, and guard cell length; for × B. caerulea, bract length and pairs of lateral veins in leaf; for B. populifolia, style length.
Phlyctochytrium arcticum n. sp. (Chytridiales); morphology and physiology
Authors: Barr D. J. S.
Published: September 2008

A chytrid with spherical, multipored sporangia, and with apophysis and rhizoids, isolated from an Arctic soil sample is described as Phlyctochytrium arcticum n. sp. It grew best at 20 C and pH 5.8–7.2. It requires exogenous thiamine, grew in ammonium nitrogen, but not in nitrate or nitrite, and used five of seven amino acids tested. It grew in glucose, fructose, trehalose, maltose, mannose, cellobiose, glycerol, and starch of 18 carbon sources tested.
A phytogeographical and phytosociological study of Viola rotundifolia in Eastern Canada
Authors: Bouchard André , Maycock Paul F.
Published: September 2008

The region of extreme southern Quebec, situated adjacent to the Appalachian Mountains, is one of considerable phytogeographic interest, particularly in terms of mountain species which entered Eastern Canada in the postglacial period. Quantitative data gathered from a large number of forest stands in the region are assembled and analyzed to determine the phytosociological and ecological position of Viola rotundifolia, which is considered to be such a species. This information is further used to ascertain the invasion patterns and attempt to explain the present geographical range of this species at its northeastern limits in North America. This analysis should prove useful in assisting to understand the phytogeography of other similar species in this region.
Preformed adventitious root initiation in brittle willows grown in a controlled environment
Authors: Haissig Bruce E.
Published: September 2008

Nodal preformed adventitious root primordia of brittle willow develop from initial cells which appear first and only in the fourth node below the terminal leaf cluster of plants grown under the described environmental conditions. The onset of root initial formation is related to the cessation of rapid aerial development which occurs at node 4, and also with the start of secondary thickening which occurs in this node. Brittle willow is an ideal subject with which to study the cellular physiology of root initials since nodes showing the earliest stages of root initial formation and development can be selected. In addition, the root initials are readily located in histological preparations.
Lignicolous marine fungi from Nova Scotia
Authors: Neish Gordon A.
Published: September 2008

Nineteen species of lignicolous marine fungi, including 13 Ascomycetes and 6 Deuteromycetes, are reported from Nova Scotia. Monodictys pelagica (Johnson) Jones and Zalerion maritimum (Linder) Anastasiou are previously reported. The other 17 species are new records for Nova Scotia.
Acclimation to Copper by Rainbow Trout (Salmo gairdneri) — A Modifying Factor in Toxicity
Authors: Dixon D. George , Sprague John B.
Published: August 2008

Lethal tolerance to copper by rainbow trout (Salmo gairdneri) increased by 60, 106, and 90% following 3-wk exposures to 0.29, 0.40, and 0.59 of the mean control incipient lethal level (ILL), 330 μg Cu/L (SD = 30; n = 25). A lower level of exposure, 0.38 ILL, represented a threshold for the onset of acclimation as tolerance was unaffected. Exposure at 0.09 ILL sensitized the trout, reducing their tolerance by 20%. The three-dimensional response surface for tolerance thus resembled a ski jump, with increases in tolerance for both duration and concentration of exposure above the threshold and sensitization below it. Because of the graded response, lethal tests on acclimated fish could be useful for rapid initial estimates of sublethal thresholds of response. Impact on growth was almost opposite to change in tolerance. Growth was reduced at 0.29, 0.40, and 0.59 ILL, enhanced at 0.18 ILL, and unaffected at 0.09 ILL. Acclimation to copper was not retained. That induced by 0.40 ILL was gradually lost during 3 wk in control water. A 4-wk exposure of fish to 0.59 ILL of copper resulted in sensitization to lethal levels of zinc. Tolerance to zinc decreased by 56%, the ILL of zinc dropping from 6.2 to 2.7 mg/L.Key words: tolerance, resistance, acclimation, copper, zinc, rainbow trout, Salmo gairdneri; toxicity
Culture à dialyse: emploi de fibres creuses dialysantes pour la culture massive de phytoplancton
Authors: Marsot Pierre , Fournier Réal , Blais Claude
Published: August 2008

The apparatus we developed for the dialysis culture of phytoplankton utilizes disposable hollow dialysis fibers (hemodialyzer) as a separate dialysis unit coupled to a growth chamber. This system provides a large-scale dialysis culture of longer duration and similar biomass values when compared to microalgae grown in small dialysis tubing. The yield of algae obtained with our dialysis system represent an important improvement over the conventional batch cultures tested.
Absence of the Protozoan Myxosoma cerebralis (Myxozoa: Myxosporea), the Cause of Whirling Disease, in a Survey of Salmonids from British Columbia
Authors: Margolis L. , McDonald T. E. , Hoskins G. E.
Published: August 2008

Myxosoma cerebralis (Hofer, 1903) was not observed in 973 wild and 4496 cultured salmonids examined from collections made in widely separated localities in British Columbia from 1968 to 1980. Species investigated were Salmo clarki (180), S. gairdneri (3688), S. trutta (16), Salvelinus fontinalis (185), S. malma (300), Oncorhynchus gorbuscha (109), O. keta (17), O. kisutch (785), O. nerka (126), and O. tshawytscha (63). Previous reports notwithstanding, in the absence of corroborative evidence British Columbia (Canada) should not be accepted as a center of M. cerebralis infection.Key words: Myxosoma cerebralis, salmonids, British Columbia, whirling disease
Behavior of Atlantic salmon (Salmo salar) During Suspended Migration in an Estuary, Sheet Harbour, Nova Scotia, Observed Visually and By Ultrasonic Tracking
Authors: Brawn Vivien M.
Published: August 2008

The movements of adult Atlantic salmon (Salmo salar) were followed in an estuary from August to November 1978 and in July and August 1979 by ultrasonic tracking. During these periods, the proportion of time spent by salmon in apparent random movement inside a small area steadily increased, reaching 97 or 98% in September and October, and then declined. This behavior was observed visually in schools of 17 to 75 salmon which showed no preference for sun or shade, were not easily disturbed, kept a constant distance from the surface associated with the halocline, and were in currents too low to measure. As the frequency of this behavior increased, average ground speed of moving fish decreased. Suspended migrations of up to [Formula: see text] mo were recorded. Salmon planted as smolts in East River and returning as adults remained almost exclusively in the East River arm of the Y-shaped estuary. Salmon favored areas having water deeper than 3 m, but showed no preference for areas deeper than 5 m inside the 3-m contour. Moving fish showed a tendency to move upstream on a rising tide and downstream on a falling tide, but these movements could be reversed by high turbine flows at the mouth of East River. A means of removing ultrasonic tags from live salmon without injury was developed.Key words: Atlantic salmon, estuary, migration, behavior, ultrasonic tracking
Preliminary Evaluation of a Method to Determine the Age of Sablefish (Anoplopoma fimbria)
Authors: Beamish Richard J. , Chilton Doris E.
Published: August 2008

Age of sablefish (Anoplopoma fimbria) was estimated using broken and burnt otoliths. A partial validation of the method was achieved using fish of known age, oxytetracycline-injected fish, and results of tagging studies. Estimated ages indicated that most sablefish stocks contain a large number of fish that are much older than previously determined using the scale method of age determination. This new information on the age and growth of sablefish indicates that strategies for the management of the sablefish fishery should be re-evaluated.Key words: sablefish, age determination, age and growth, otoliths, age validation, fisheries management
Fish Abundance and Distribution Near Three Heated Effluents to Lake Michigan
Authors: Spigarelli S. A. , Goldstein R. M. , Prepejchal W. , Thommes M. M.
Published: August 2008

A combined echo location–temperature mapping technique was used to determine the abundance and distribution of fish with depth and temperature in locally heated and unheated areas of Lake Michigan. Surveys were conducted between April and October at two adjacent power plants in the southern basin and at one plant in the northern basin of the lake. Fish densities in plume and reference areas differed seasonally. Densities typically differed by a factor of 2–4 although on one occasion plume area density was 90 times greater. Highest plume densities occurred during late spring when alewife (Alosa pseudoharengus) were spawning inshore. Consistently dense congregations of fish were found downstream of the interfaces between ambient shore-parallel currents and discharge flows. The general distribution of fish with depth was similar in all areas. Differences between plume and reference areas were related to the discharge type: at canal discharges fish tended to congregate inshore while at the offshore discharge they congregated in deeper zones. Fish also tended to occupy shallower depth strata in all plume areas. Positive correlation between fish density and increasing temperature was common at both plume and reference areas during all three seasons, but more frequent at plume areas. Temperatures selected by fish in plume areas were 1–3 °C higher than maximum ambient temperatures.Key words: fish distribution, thermal outfall, temperature, depth, discharge type, Lake Michigan
Behavioral Interactions and Body Size Differences in Competition for Food among Juvenile Brown Bullhead (Ictalurus nebulosus)
Authors: Keen W. Hubert
Published: August 2008

The effects of relative body size (larger or smaller fish), absolute body size differences, food level, and social interactions on the growth rates of juvenile brown bullhead (Ictalurus nebulosus) catfish were determined for pairs of fish. Overall growth rate of the larger fish was higher than for the smaller fish, although this difference did not depend on absolute body size difference within pairs. The reduced growth rates of both larger and smaller fish at limited food level was independent of both relative size difference and absolute body size difference within pairs. Both larger and smaller fish had highly variable growth rates. Size dominance and aggression were common within many pairs, yet this behavior was unrelated to food level and absolute body size difference. Aggression within pairs was not diminished by adding structural complexity to simple environments. It is suggested that the high variability in growth rates was due to differences in individuals within pairs with respect to the intensity of behavioral interactions. Social interactions within pairs offish were apparently unrelated to food level and were strong enough to mask both exploitative and interference mechanisms which may have been functional in competition for limited food.Key words: body size, dominance hierarchies, exploitation competition, food level, Ictalurus nebulosus, interference competition, behavioral interactions
Difficulties in Aging Atlantic Salmon (Salmo salar) and Brown Trout (Salmo trutta) from Cold Rivers Due to Lack of Scales as Yearlings
Authors: Jensen Arne Johan , Johnsen Bjørn Ove
Published: August 2008

Scales in Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) from two cold Norwegian rivers first appeared when the salmon were 33–34 mm long (total length) and the trout were 35–38 mm long. A considerable proportion of the yearlings did not form scales in years with a low water temperature (less than 1000–1100 degree-days from May to October); these individuals lacked the first annulus in the scales. Scales with five circuli or more seldom occurred. The number of days per year with a water temperature above 6.5 °C was better correlated to the formation of scales in Atlantic salmon than the degree-days. In years when the water temperature exceeded 6.5 °C for more than 70–80 days, only minor errors arose in age determination of the salmon; when the temperature exceeded 6.5 °C for less than 70–80 days, some individuals lacked the first annulus in their scales.Key words: Atlantic salmon, brown trout, age determination, temperature, scale formation
Primary Production and Nutrient Assimilation by Natural Phytoplankton Populations of the Eastern Canadian Arctic
Authors: Harrison W. G. , Platt Trevor , Irwin Brian
Published: August 2008

Phytoplankton biomass (chlorophyll a) and primary production rates in Baffin Bay during summer 1978 were comparable to levels reported for other open water arctic and subarctic regions. Values were moderately high ([Formula: see text] mg Chl∙m−2; 227 mg C-fixed∙m−2∙d−1) considering the low mixed-layer nutrient (nitrogen) concentrations, low ambient temperatures ([Formula: see text] euphotic zone = −0.2 °C), and variable and moderately low daily solar radiation ([Formula: see text] MW∙m−2). Biomass maxima were consistently found at or near the bottom of the euphotic zone, and were 6 times higher than surface values on the average. Nitrate and ammonium were assimilated in approximately equal proportions despite the relatively greater abundance of nitrate in the euphotic zone, particularly below the mixed layer. Average C:N assimilation ratios were slightly lower (5:1) than the chemical composition ratio of the particulate matter (7:1). High phosphate assimilation rates reflected the abundance of this nutrient in the euphotic zone and resulted in low C:P (22:1) and N:P (6:1) assimilation ratios. Growth rates computed from carbon and nitrogen (NO3− + NH4+) assimilation rates averaged 0.31 and 0.35 doublings∙d−1, respectively, for the euphotic zone, and were half the maximum expected growth rates for prevailing water temperatures and optimal conditions of light and nutrients. Baffin Bay phytoplankton populations exhibited no obvious signs of severe nitrogen limitation despite low euphotic zone concentrations of the nutrient. Furthermore, the strong correspondence between: (1) normalized primary production rates (photosynthetic index) and incident solar radiation and (2) growth rates and incubation temperatures suggests that nutrients may play a relatively less important role in controlling arctic primary production than previously considered.Key words: phytoplankton, primary production, nutrients, arctic, light, and temperature
Temperatures Selected in a Power Plant Thermal Effluent by Adult Yellow Perch (Perca flavescens) in Winter
Authors: Ross Marvin Jon , Siniff Donald B.
Published: August 2008

Winter-temperature selection by yellow perch (Perca flavescens) was monitored by radio telemetry near the thermal discharge from a power plant on the Upper Mississippi River. Ten fish were equipped with temperature-sensing radio transmitters. Temperature selection was monitored with an automatic recording system and manually with standard radio frequency receivers. The selected mean winter temperature for all locations was 5.4 °C; when fish were in the discharge area mean temperature selected was 6.3 °C. Ninety-one percent of the temperatures was recorded from fish in the discharge bay. Response to temperature varied greatly among individual fish, and they selected significantly lower temperatures in the field than in laboratory experiments. These field-selected temperatures correspond closely to those required for gametogenesis and spawning success in this species.Key words: Perca flavescens, thermal requirements, radio telemetry, temperature selection
Rate of Gastric Evacuation for Winter Flounder, Pseudopleuronectes americanus
Authors: Huebner Judith D. , Langton Richard W.
Published: August 2008

The rate of gastric evacuation of winter flounder, Pseudopleuronectes americanus, calculated from the rate of hunger return (determined as the amount eaten voluntarily at some time following a satiation meal) at ~ 6 °C was exponential and equaled 0.079 h−1. Feeding voluntarily on small pieces of squid, the fish ate 1.8–2.4% of their body weight per day, the actual weight of food consumed varying directly with fish weight so that ln wt food (g) = −2.988 + 0.780 ln wet wt fish (g). Stomach volume also varied with fish weight: stomach vol (cm3) = 0.923 + 0.039 wet wt fish (g). Preliminary estimates of daily ration using several independent models agree closely with laboratory measurements of daily consumption.Key words: winter flounder, gastric, evacuation
Effects of Upwelling on Local Abundance and Distribution of Larval Alewife (Alosa pseudoharengus) in Eastern Lake Michigan
Authors: Heufelder George R. , Jude David J. , Tesar Frank J.
Published: August 2008

Intrusion of cold (usually < 10 °C), hypolimnetic water into the Lake Michigan nearshore zone (≤ 15 m) substantially changed local abundance and distribution of larval alewife (Alosa pseudoharengus) during the summers of 1977–79. During upwelling, larval fish densities were reduced to below 1000 larvae/1000 m3; when no upwelling occurred densities commonly exceeded 5000 larvae/1000 m3. Widespread distribution to depths of at least 15 m was found in the absence of upwelling, while during upwelling larvae were more concentrated in water ≤ 6 m deep. Additionally, at depths > 3 m during upwelling, alewife larvae were most abundant in bottom strata, a trend not observed in the absence of upwelling. Postulated mechanisms for reduced larval alewife abundance in inshore areas during upwelling include mortality of larvae due to thermal shock, and offshore or alongshore movement, either actively by larvae and potential spawning adults, or passively by larvae.Key words: Alosa pseudoharengus larvae, distribution, abundance, Lake Michigan, upwelling
Experimental Impoundments of Prespawning Pacific Herring (Clupea harengus pallasi): Effects of Feeding and Density on Maturation, Growth, and Proximate Analysis
Authors: Hay D. E. , Brett J. R. , Bilinski E. , Smith D. T. , Donaldson E. M. , Hunter G. A. , Solmie A. V.
Published: August 2008

Approximately 3 mo before spawning, Pacific herring (Clupea harengus pallasi) were captured and transferred to experimental netpens and subjected to different holding conditions: high, medium, and low densities; with and without covers; and fed and not fed. Mortality during impoundment was low. There were no detectable effects of density or cover, but feeding accelerated spawning time and promoted gonadal growth. Fed fish had significantly higher somatic weights, gonad weights, and condition factors and significantly lower gonosomale indices than unfed fish. Water content increased in all fish from about 70%, at the beginning, to about 75% when the fish were ripe. Consequently, total body weight increased in all females, and somatic weight decreased, but the decrease was feast in the fed fish. No significant differences in the percentages of total protein and ash in the carcass were found during impoundment, but the levels of fat and free fatty acids showed a progressive decrease. Glycogen levels in the muscle and liver were higher in fed herring. Oocyte maturation was normal. Preovulatory atresia of vitellogenic oocytes was observed in all groups. Egg diameters of fed females were slightly larger than those of unfed fish. The evidence for winter feeding in Pacific herring is evaluated.
Variation in the Condition of Northern Pike, Esox lncius
Authors: Doyon Jean-François , Downing John A. , Magnin Etienne
Published: August 2008

The relationship between condition and latitude, temperature, and sex of northern pike (Esox lucius) was examined by regression analysis of 5210 published observations drawn from more than 38 populations. Most populations showed nearly isometric growth, but the overall exponent of the power function relationship between total body length and body weight was slightly less than 3 (p < 0.01). Multiple regression analysis showed that females weighed about 9% more than males of equal length, that body weight for fish of equal length increased about 5% for every 10° increase in north latitude and increased about 4% for every 10 °C decrease in mean annual air temperature, and that fish in European and Asian populations attained about 13% greater weight for a given length than their North American counterparts.
Meristic Composition of Sand Lance (Ammodytes spp.) in Newfoundland Waters with a Review of Species Designations in the Northwest Atlantic
Authors: Winters G. H. , Dalley E. L.
Published: August 2008

Examination of new meristic data on sand lance (Ammodytes spp.) populations in Newfoundland coastal waters using a combination of discriminant function and modal analyses demonstrates for the first time that co-occurrence is a common feature of the distribution of the two species (A. dubius and A. americanus) provisionally considered to exist in the Northwest Atlantic. In addition, the consistency in the meristic counts of A. dubius between the offshore and inshore samples and the postulated spawning of A. dubius in Newfoundland coastal waters provides good evidence that A. dubius is reproductively isolated from A. americanus. Reanalysis of published data on the vertebral composition of sand lance in the Northwest Atlantic confirms the co-occurrence of A. americanus and A. dubius in inshore areas from West Greenland southwards to the Gulf of Maine. These new analyses taken together with a review of the major distinguishing characteristics of sand lance species in the North Atlantic waters lead us to conclude that the heterogeneous assemblage of sand lance found inshore from West Greenland southwards and offshore from Georges Bank southwards and which has traditionally been classified as A. americanus belongs to a single trans-Atlantic species, A. marinus.
Evidence of Demic Structure for a Population of Yellow Perch (Perca flavescens)
Authors: Aalto S. K. , (Buck) Newsome G. E.
Published: August 2008

A number of authors suggest that yellow perch (Perca flavescens and P. fluviatilis) populations are composed of subpopulations which persist over various periods of time. If the period of time is sufficiently long, then subpopulations may be demes or stocks of perch. These observations are based on the results of tagging studies, comparative growth studies, and behavior patterns of yellow perch. In this paper, evidence is presented which provides additional support for demic structure of yellow perch populations. This evidence consists of yearly egg-mass counts over an extended period of time (1978–87) at a number of distinct sites in a study lake and trapping data by sex, age, and date during one spawning season (1984) at a number of distinct sites in the same lake. Several models concerning perch spawning behavior are introduced to provide a framework for analyzing the data. Analysis of the data not only provides support for demic models of perch population structure, but also provides an estimate of the separation of the demes (0.4–0.5 km).
Role of Off-Channel Ponds in the Life Cycle of Coho Salmon (Oncorhynchus kisutch) and Other Juvenile Salmonids in the Coldwater River, British Columbia
Authors: Swales S. , Levings C. D.
Published: August 2008

Off-channel ponds in the upper reaches of the Coldwater River, British Columbia, were major rearing areas for juvenile coho salmon (Oncorhynchus kisutch). Chinook salmon (Oncorhynchus tshawytscha), steelhead trout (Salmo gairdneri), and Dolly Varden char (Salvelinus malma) were generally scarce in the ponds, although they were numerous in the main river. Coho salmon were predominant at "natural" river sites while steelhead trout was the main species at sites with "rip-rap" bank stabilization. Catches of juvenile coho were much lower in the main river than in the ponds where they were the main species, and were more variable in the river. Population density and biomass estimates of juvenile coho in the ponds ranged from 0.100 fish∙m−2 and 1.00 g∙m−2 to 1.00 fish∙m−2 and 5.15 g∙m−2, compared with density estimates of 0.08–0.23 fish∙m−2 in the river. The coho population in the ponds consisted of 0+ and 1+ age-groups in similar proportions, while in the main river the 0+ age-group was much more abundant. The growth rate of coho in the ponds was faster than in the main river, with pond fish reaching mean lengths of 62–79 mm at the end of the first growing season, compared with 53 mm in the main river. Smolt outmigration from the main study pond occurred in late spring with peak outmigration in May and June coinciding with peak river discharge and increasing water temperatures in the main river and pond.
Response of Limnetic Insect Populations of Two Acidic, Fishless Lakes to Liming and Brook Trout (Salvelinus fontinalis)
Authors: Evans Richard A.
Published: August 2008

Seasonal population density estimates of limnetic insects in two Adirondack (New York) lakes were obtained from horizontal and vertical net tows and benthic sweep net samples over a 3-yr period; 1 yr while the lakes were acidic and fishless, and 2 yr following addition of (calcium carbonate) CaCO3 and the introduction of brook trout (Salvelinus fontinalis). Before treatment, the limnetic insect assemblages in the study lakes resembled those reported from acidic and/or fishless lakes in Sweden and Canada. Maximum densities of dominant taxa were: Notonectidae; 1.5∙m−3; Corixidae; 1.1∙m−3, Graphoderus (Dytiscidae) larvae; 0.27∙m−3; and Chaoborus americanus; 400∙m−3. Within 3 mo after treatment, all limnetic populations were near or below the detection limit (0.01∙m−3). Limnetic densities of notonectids, corixids, and C. americanus were significantly lower (Mann–Whitney U-tests), and benthic densities of Hemiptera and Coleoptera tended to be lower (sign tests) the summer after treatment than the previous summer. Calculated trout predation levels on Hemiptera and C. americanus, and evidence from the literature, strongly suggest that predation was the major cause of reduced limnetic insect populations. The rapid reduction or elimination of these populations indicates considerable instability of the predator–prey relationships of acidic lakes which have been recently limed and stocked with fish.
Scale Morphology as an Index of Developmental Stability and Stress Resistance of Tilapia (Oreochromis niloticus)
Authors: Shackell Nancy L. , Doyle Roger W.
Published: August 2008

Growth and the stabilities of growth and development were examined in inbred, outbred, and interstrain hybrid lines of tilapia (Oreochromus niloticus) under two diet regimes. Developmental stability was quantified as the inverse of the number of deformed scale circuli (calcified ridges). Growth stability was measured as the inverse of the individual variability of circulus spacing (circulus spacing is an indirect measure of growth rate). Each line was fed an alternating diet of low-protein rice bran and high-protein commercial pellet or a constant diet of commercial pellet. Diet regime had a significant effect on growth, developmental stability, and growth stability. Genetic composition of line had a significant effect only on developmental stability. Inbred lines had lower developmental stabilities than outbred lines. Hybrid progeny had higher developmental stability than the average of the parent strain values. Faster growing individuals had higher developmental and growth stabilities and lower growth stabilities (only within the commercial pellet regime). Composite indices of "merit" can be constructed by combining the variables, according to the correlations among variables and breeding objectives.
Bioassay-Derived 2,3,7,8-Tetrachlorodibenzo-p-dioxin Equivalents in PCB-Containing Extracts from the Flesh and Eggs of Lake Michigan Chinook Salmon (Oncorhynchus tshawytscha) and Possible Implications for Reproduction
Authors: Ankley Gerald T. , Tillitt Donald E. , Giesy John P. , Jones Paul D. , Verbrugge David A.
Published: August 2008

Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ), derived via the H4IIE rat hepatoma cell bioassay, were measured in polychlorinated biphenyl (PCB) containing extracts of flesh (dorsal muscle) and egg samples from 10 spawning chinook salmon (Oncorhynchus tshawytscha) from Lake Michigan. There was a marked maternal transfer of both TCDD-EQ and PCBs, and potency of the PCB mixture (expressed as picograms of TCDD-EQ per microgram of PCB) in eggs was 2.5 times greater than potency of the PCB mixture in dorsal muscle of the fish. There was a statistically significant, inverse relationship between the total concentration of PCBs in eggs and hatching success of the fish, with an effect concentration that corresponded to approximately 100 pg TCDD-EQ/g egg. Our results, based on a relatively small sample size, suggest that PCBs, in particular those with TCDD-type activity, may have influenced reproductive success of the fish.
Induction of Foci of Cellular Alteration and Other Hepatic Lesions in English sole (Patophrys vetulus) Exposed to an Extract of an Urban Marine Sediment
Authors: Schiewe Michael H. , Weber Douglas D. , Myers Mark S. , Jacques Frank J. , Reichert William L. , Krone Cheryl A. , Malins Donald C. , McCain Bruce B. , Chan Sin-Lam , Varanasi Usha
Published: August 2008

Epizootiological analyses of field data on prevalances of hepatic neoplasms and other hepatic lesions in English sole (Parophrys vetulus) from Puget Sound suggest a link between these lesions and sediment-associated xenobiotics, particularly aromatic hydrocarbons (AHs). To further investigate this relationship, English sole from a minimally contaminated site were parenterally exposed at monthly intervals for 1 yr to an organic solvent extract of a contaminated urban sediment containing high levels of AHs (30 or 75 mg/kg body weight) or to the model carcinogen benzo[a]pyrene (BaP, 12 mg/kg body weight). Control groups included English sole exposed to an extract of a relatively uncontaminated reference sediment, sole exposed to the carrier only, and untreated sole. Eighteen months after the initial injections, examination of livers revealed a significantly different (increased, [Formula: see text]) incidence of a spectrum of hepatic lesions, including presumptive preneoplastic foci of cellular alteration, in sole exposed to the urban sediment extract or BaP. Sole in control groups did not develop any of these hepatic lesions. These results represent the first direct demonstration of the hepatotoxicity of sediment-associated chemical contaminants in English sole and strengthen the case for a cause-and-effect relationship between exposure to AHs and epizootic neoplastic hepatic lesions in this species.