bluuebunny/crossref_metadata_2025 huggingface dataset:
Réponse numérique de l'hermine aux fluctuations d'abondance de Microtus pennsylvanicus
Authors: Raymond Michel , Bergeron Jean-Marie
Published: August 2008

The numerical response of two ermine populations (Mustela erminea) to the density fluctuations of the meadow vole (Microtus pennsylvanicus), the dominant mammal in southern Quebec agrosystems, was studied from 1978 to 1980. There is a strong correlation between the densities of the two species, whether or not the fluctuations of Microtus are cyclical. Males and females show a different response, the numerical adjustment of males being strongly correlated to the fluctuations of the vole population while the females do not seem to make particular adjustments. The numerical response of the ermine takes place only a few months after the changes in the rodent population. It is suggested that in areas where preys are small and of similar size the survival of the females is less dependent than that of the males on the density of the dominant prey. As most female ermines seem to participate in reproduction whatever the density of the vole population, the continuity of any local population is insured from year to year by the presence of at least minimal numbers. Survival of the young during the year following their birth seems to depend on the immediate availability of prey, thus determining the characteristics of the numerical response.[Journal translation]
Electrophoretic and electron microscopic examination of the adductor and diductor muscles of an articulate brachiopod, Terebratalia transversa
Authors: Eshleman William P. , Wilkens Jerrel L. , Cavey Michael J.
Published: August 2008

The proteins of the striated adductor muscles, smooth adductor muscles, and diductor muscles of the articulate brachiopod Terebratalia transversa have been examined by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Electrophoretic patterns indicate the presence of paramyosin in all of these valve muscles. Tentative identification has also been made of the proteins responsible for actin and for myosin regulation of contraction (troponin–tropomyosin and myosin light chains, respectively). The myofilaments of the striated adductor cells, smooth adductor cells, and diductor cells have been characterized by transmission electron microscopy. The smooth adductor cells and the diductor cells exhibit very thick myofilaments which are fusiform in shape, exceptionally long, and axially banded. Morphological features of these thick myofilaments are consistent with those of paramyosin filaments found in other muscles and myoepithelia. Although the striated adductor cells contain paramyosin, it is not manifest in the thick myofilaments.
Relative size of brain and brain components in three gliding placentals (Dermoptera: Rodentia)
Authors: Pirlot Paul , Kamiya Toshiro
Published: August 2008

The relative weight and the volumetric composition of the brains of Cynocephalus, Iomys, Glaucomys, and pteropodids are compared. It appears that in three well separated mammalian orders and at different places and times, a fairly similar subdivision of the brain was brought about by evolution, which is considered to be a result of a general parallelism in ecological conditions and behaviour.
The effect of 5-bromodeoxyuridine on limb regeneration in the newt Notophthalmus viridescens
Authors: Scadding Steven R.
Published: August 2008

The effect of the thymidine analogue 5-bromodeoxyuridine (BrdU) on limb regeneration in the newt was studied at three different dose levels. At 50 μg per day, there was no effect on regeneration in most cases. However, in about 20% of the cases there was a slight retardation of regeneration. At 250 μg per day, there was a partial inhibition of regeneration including reduction in blastema size, reduction in epidermal thickness, and less extensive muscle dedifferentiation. At 1 mg per day, there was a complete inhibition of limb regeneration; however, this dosage was also lethal to the newts. No specific effect of BrdU on cell differentiation was observed. The differences and similarities to BrdU effects on various cultured cells are discussed.
Vegetative structure, concealment, and success at nests of two races of spruce grouse
Authors: Redmond G. W. , Keppie D. M. , Herzog P. W.
Published: August 2008

Vegetative structure, concealment, and success were compared at nests of two races of spruce grouse: Canachites canadensis canace (N = 37) in New Brunswick (1976–1980) and C. c. franklinii (N = 67) in Alberta (1970–1975). Nests of both races were similar in design and were often located near the bole of trees or near the perimeter of tree or shrub clumps. Female spruce grouse, particularly in New Brunswick, nest in an array of stand types, densities, and ages. Hens may use certain structural cues when choosing areas to nest since canopy closure, density and percent ground cover, and density of trees at nest sites were different from what was generally available. Concealment and success at nests of canace were significantly greater than at franklinii nests. We attribute these differences partially to the absence of a uniform dense layer of dwarf shrub ground vegetation in Alberta. Nests of adults of both races were better concealed than nests of yearlings and well-concealed nests usually were successful.
Thyroxine treatments in vivo and ultrastructural differentiation of chicken (Gallus gallus) embryo duodenum
Authors: Brewer Linda M. , Betz T. W.
Published: August 2008

Previously, L-thyroxine (L-T4) treatment of 16.5-day-old chicken embryos (approximately stage 42) correlated with a precocious increase in prehatching duodenal alkaline phosphatase specific activity. This paper examines the effects of similar L-T4 treatment on ultrastructural differentiation of the absorptive epithelium. White Leghorn embryos (strain Hyline 934F of Gallus gallus) were given 0.1 mL of saline containing 5-μg doses of either L-T4, or D-T4, or saline vehicle alone through windows in the shell. Untreated windowed and intact unwindowed embryos were additional controls. At the time of treatment (16.5 days) and 24, 48, and 72 h later embryos were killed and their duodena were fixed. At least three embryos were examined in each group. Twenty-four hours after treatment stage 43 epithelial cells resembled stage 42 cells. Forty-eight and 72 h following L-T4 treatment stage 44 and 45 embryos showed evidence of increased Golgi and lysosome activity but depletion of lipid droplets and glycogen stores. Control treatments with D-T4 or saline vehicle did not appear to affect epithelial cell ultrastructure as these embryos resembled unwindowed and windowed control embryos at all stages.
Shell size divergence in Littorina mariae and L. obtusata and predation by crabs
Authors: Reimchen T. E.
Published: August 2008

On the British and Irish coasts, Littorina mariae and L. obtusata show geographical variation in adult shell size, the former decreasing and the latter increasing in localities with increased protection from wave action. Within some shores, L. obtusata is relatively small in upper tidal positions but increases in size towards the lower shore where it overlaps with the much smaller shelled L. mariae.Characteristic signs of repair observed on the shells are considered to have resulted from unsuccessful attacks by crabs such as Carcinus maenas. High frequencies of these shell injuries were associated with the presence of large-shelled populations of L. obtusata both between localities and between different levels on the shore.Experimental work showed that large-shelled L. obtusata (16–17 mm) were exceptionally resistant to breakage by large C. maenas while smaller adult shells of L. obtusata (13–16 mm) and those of L. mariae (6–13 mm) were very susceptible. Small C. maenas were unable to successfully crack the thickened outer whorl of adult shells of either species and could only break the thin shells of juveniles. It is argued that small adult size, as seen in L. mariae, could represent an adaptation for a contracted juvenile stage and thus early maturity where small crabs are important predators.
Innervation and fine structure of antennal sensilla of Simuliidae larvae (Diptera: Culicomorpha)
Authors: Craig Douglas A. , Batz Harold
Published: August 2008

Light, scanning electron, and transmission electron microscopy were used to investigate fine structure and innervation of antennal sensilla of Simuliidae larvae with particular attention to a bacteria-covered structure superficially similar to chloride-absorbing cells of other aquatic insects.Eight sensilla of five morphological types innervated by a total of 22 neurones are described. A single uniporous cone sensillum, with five distal dendrites in a common dendritic sheath is on the antennal apex. Two multiporous peg sensilla, each with two distal dendrites in separate, but fused dendritic sheaths, are at the base of the distal antennal article. Near the base of the proximal antennal article on the membranous antennal base is a single trichoid sensillum, probably with a single distal dendrite. Ventral to the base of the antennal articles is the bacteria-covered structure, shown here to be a multiporous sensillum, with five distal dendrites invested in a fused dendritic sheath, which has a foamy appearance and is fenestrated. A pore tubule system is described for this sensillum, the first time for sensilla of any aquatic insect. The sensillum is internally surrounded by a heavily cuticularized capsule which is supported laterally by buttresses and is penetrated by a canal, through which the dendrites enter.Because of a peculiar feature of moulting in Simuliidae larvae, the sensillar sinus of this sensillum is open to the moulting space between cuticle and epidermis. The cellular portion of that sinus is closed off.Probable gram-negative bacteria on this sensillum appear to prefer sensillar exudate. Comparison of chloride concentration in this sensillum, with that of another multiporous sensillum, using energy-dispersive X-ray spectrometry, showed no significant differences, indicating no enhanced chloride absorbing function for the former sensillum.The bacteria-covered sensillum is always closely accompanied by a trichoid sensillum innervated by a single distal dendrite with a tubular body.Two small uniporous peg sensilla located anteroventrally on the membranous antennal base have three distal dendrites each. In the large ciliary sinuses these dendrites become highly lamellated, bound with pleated septate junctions, and associated with concentrations of mitochondria. It is suggested that these lamellae have a secretory–absorbtive function.On the basis of similarity in structure and number, tentative homologies with antennal sensilla of other Culicomorpha larvae are suggested.
Effects of 5-hydroxytryptamine and histamine on establishment, production, and reproduction by Hymenolepis diminuta in the final and intermediate hosts
Authors: Cho C. H. , Mettrick D. F.
Published: August 2008

The effects of chronic administration of 5-hydroxytryptamine (serotonin, 5-HT) and histamine for 15 days, commencing 24 h after infection, on establishment, production, and reproduction by the tapeworm Hymenolepis diminuta in the rat intestine have been studied. Chronic treatment with 5-HT at the rate of 10 or 20 mg/rat per 24 h neither affected parasite production (growth) nor caused a significant rejection of the infection by the rat host. The number of eggs shed by the parasite and the number of eggs per gravid proglottid were reduced over the final 24-h period prior to sacrifice of the hosts.Similar treatment with histamine at the higher dose rate resulted in a significant reduction in the size of the infection and a significant increase in average worm weight. The number of eggs per gram of faeces and per proglottid was significantly reduced, as was also the number of cysticercoids that developed in beetles (Tribolium confusum) that had been fed on the gravid proglottids from histamine-treated worms. Results at the lower dose rate were similar, although the changes were smaller. The histamine treatment may have induced an immunological response by the host to the infection similar to that previously reported for this particular host–parasite system at higher levels of infection or in challenge infections.
The evolutionary process in talitrid amphipods and salamanders in changing environments, with a discussion of "genetic assimilation" and some other evolutionary concepts
Authors: Matsuda Ryuichi
Published: August 2008

The evolutionary process of talitrid amphipods and salamanders involving neoteny in changing environments consists of the aspect of environmental induction of structural changes as a result of altered activity of the preexisting endocrine mechanism and the aspect of natural selection which results in canalization of development and genetic assimilation of the modified (neotenous) phenotype. The prevalence of genetic assimilation is discussed, along with the cases where traditional neo-Darwinism applies. By taking the fact of environment–hormonal induction of gene regulation and the aspect of natural selection into account, mechanisms of macroevolution, preadaptation, plasticity in morphogenesis, and a mode of speciation are discussed. A historical review is presented concerning the theories (the Baldwin effect and Weismann's theory) related to genetic assimilation and neo-Darwinism.
The biology of two Eimeria species (Protista: Apicomplexa) in their mutual fish hosts in Ontario
Authors: Paterson W. Brockley , Desser Sherwin S.
Published: August 2008

Eimeria degiustii and E. iroquoina were studied in natural infections of their mutual cyprinid hosts the common shiner, Notropis cornutus, and the fathead minnow, Pimephales promelas. Experimental infections involved lab-reared fathead minnows. Oocysts were acclimated to different temperatures to investigate the effects upon the parasites' development and infectivity.Eimeria degiustii occurred at 21% prevalence in common shiners 2 years of age or older. Development was parenteral. Gametogony was recorded during the winter in the spleen and oocysts were found primarily in this site.Viurtally all Notropis cornutus 4 to 5 weeks of age were infected with E. iroquoina. Fish 1 year old or older act as reservoirs of infections with about 30% prevalence. Eimeria iroquoina develops in the intestinal epithelium, primarily immediately posterior to the bile duct. During the winter autoinfection of the posterior intestine possibly occurs. Transmission of E. iroquoina from N. cornutus to P. promelas demonstrates this parasite's lack of rigid host specificity.Eimeria degiustii and E. iroquoina appear to minimize competition in mutual hosts by infecting different age-classes in different sites and by forming oocysts primarily at different times of year. Eimeria iroquoina is transmitted directly. Eimeria degiustii probably requires an invertebrate intermediate host.
Interpreting the diet of Rhyacophila larvae (Trichoptera) from gut analyses: an evaluation of techniques
Authors: Martin Ian D. , Mackay Rosemary J.
Published: August 2008

Three commonly used gut analysis techniques were compared for reliability in determining the food habits of fifth-instar Rhyacophila fuscula (Walker) larvae. The predaceous Rhyacophila were fed a known number of each of two prey taxa (Ephemeroptera; Ephemerellidae, and Diptera: Chironomidae) in an artificial stream under controlled conditions in the laboratory. Rhyacophila attacked equal numbers of both prey types during the experiment. Two gut analysis techniques, (1) frequency of occurrence of particular prey in the guts, and (2) the relative abundance of each prey in the guts, gave results similar to those expected. The third technique, a frequently used quantitative method which uses relative areas of the diet items, gave a significantly biased interpretation of prey selection by R. fuscula. The indiscriminate application of any of these methods may lead to errors in interpreting the diet of individual predator taxa, and consequently, incorrect conclusions in studies of comparative feeding ecology.
Space utilization in a community of temperate reef fishes inhabiting small experimental artificial reefs
Authors: Gascon Dominique , Miller Roberta A.
Published: August 2008

Using multidimensional contingency table analysis, we investigated the pattern of space use in an assemblage of nearshore reef fishes inhabiting small artificial reefs in Barkley Sound, British Columbia. Two variables, (1) shelter type and size, and (2) elevation above substrate, were specifically studied. All species had precise microhabitat requirements, and they all showed segregation in the spatial dimension, with the exception of the pair Sebastes caurinus – S. maliger. Only Sebastes melanops showed consistent shifts in its space use in response to increases in the density of the other members of the community, indicating that, with this exception, interspecific competition was probably a weak force in this system.
Summer home range and habitat utilisation of the red fox (Vulpes vulpes) in a tundra habitat, northwest British Columbia
Authors: Jones Donald M. , Theberge John B.
Published: August 2008

Eight adult red foxes (Vulpes vulpes) were radio tracked during the summers of 1978 and 1979 in an alpine and subalpine environment of northwest British Columbia. The spatial distributions of small mammals (mice, voles, and shrews) and arctic ground squirrels (Spermophilus parryii) were ascertained to complement the telemetric study. Summer home ranges averaged 1611 ha (range = 277–3420 ha) and were larger than vulpine ranges in temperate environments. Significant habitat selection was evident in five of the seven home ranges that were examined. Salix shrub communities were preferred habitats, whereas, open lichen – Empetrum and fen communities were avoided. Relative densities of small mammals and arctic ground squirrels varied significantly among plant communities. Possible explanations, considering the diet of the fox and the spatial distribution of its prey, are offered to account for the observed patterns of home-range size and habitat utilisation.
Penetration of horseradish peroxidase into the extravascular channel system of in vitro European eel (Anguilla anguilla) pars distalis, with comments on the role of the nongranulated cells
Authors: Leatherland John F. , Baker Bridget I.
Published: August 2008

Horseradish peroxidase (HPO) was used as an extracellular space marker to investigate the characteristics of the extravascular network in in vitro cultured hemipituitaries of Anguilla anguilla. HPO penetrated large extravascular channels in both the rostral and proximal pars distalis. In the rostral pars distalis the channels were associated with the base of the columnar prolactin cells and in the basal lamina between the corticotropes and anterior neurohypophysis in the dorsal region. In the proximal pars distalis the channels separated the cords of granulated cells. HPO also penetrated into fine extracellular spaces, which appeared to be continuous with the extravascular channels, in both rostral and proximal pars distalis. HPO penetrated only those extracellular spaces associated with the nongranulated (NG) cells, suggesting a related function between the movement of large molecules in the extravascular network and NG cell function. However, in in vitro situations which alter pars distalis cell activity (altered osmotic pressure of the incubation medium or incubation in the presence of metabolic inhibitors such as dinitrophenol or KCN) penetration of HPO did not appear to be affected, suggesting that the HPO penetration was passive, at least in the in vitro conditions used here.
Small mammal and habitat response to shoreline cottage development in central Ontario
Authors: Racey G. D. , Euler D. L.
Published: August 2008

Changes in small mammal abundance and habitat caused by shoreline cottage development in central Ontario were studied in the summers of 1978 and 1979. This development significantly altered the vegetation composition and structure in the vicinity of cottages. These alterations, in turn, had an impact on small mammal abundance. These animals were classified in three response categories: tolerant (existing, at some level, regardless of degree of development), intolerant (extirpated at high levels of development), and indifferent to development. Tolerant species were the eastern chipmunk (Tamias striatus), short-tailed shrew (Blarina brevicauda), and deer mouse (Peromyscus maniculatus); intolerant species were the masked shrew (Sorex cinereus), red-backed vole (Clethrionomys gapperi), and woodland jumping mouse (Napeozapus insignis). The red squirrel (Tamiasciurus hudsonicus) was indifferent to development. Small mammal diversity was highest on mixed shorelines at moderate levels of development. Species diversity appeared to respond positively to vegetative composition, edge effect, and irregularity of habitat. These characteristics were all dependent on the level of cottage development.
Sarcocystis wapiti sp. nov. from the North American wapiti (Cervus elaphus)
Authors: Speer Clarence A. , Dubey J. P.
Published: August 2008

Sarcocystis wapiti sp. nov. (Eimeriina: Sarcocystidae) is described as a heteroxenous coccidian with dogs (Canis familiaris) and coyotes (Canis latrans) as the final hosts and wapiti (Cervus elaphus) as the natural intermediate host. Sarcocysts in various muscle tissues of the wapiti were micro- to macroscopic, had a thin primary cyst wall and septa, and measured 652 × 322 μm. Sarcocysts contained numerous bradyzoites that were 16.1 × 2.4 μm and few metrocytes that were 11.2 × 4.6 μm. Ten days after ingesting Sarcocystis-infected wapiti meat, a dog and a coyote began passing oocysts and sporocysts in their feces; a domestic cat did not pass oocysts or sporocysts after ingesting infected meat from the same animal. Sporulated oocysts measured 20.3 × 15.6 μm; sporocysts were 15.9 × 10.6 μm. Twelve days after ingesting wapiti meat, oocysts of S. wapiti were found in the lamina propria of the distal one-third of the villi of the small intestine of the coyote. Bradyzoites were found in digests of muscle tissue of 58 of 65 wapiti.
Levels of male aggressiveness in fluctuating populations of Microtus ochrogaster and M. pennsylvanicus
Authors: Hofmann Joyce E. , Getz Lowell L. , Klatt Brian J.
Published: August 2008

Levels of male aggressiveness, determined by observation of dyadic encounters, were compared during low, increase, peak, and decline phases of the population cycle in free-living populations of Microtus ochrogaster and M. pennsylvanicus. There were no significant differences in the proportions of nonaggressive, aggressive, and highly aggressive males during the low, increase, and peak phases of M. ochrogaster populations in an alfalfa and in a bluegrass habitat. Large numbers of nonaggressive voles were present during the decline phases. The aggressiveness of individual males appeared greater at peak densities only in the bluegrass field. Phase of cycle explained 18.6% of the variation in behavioral variables for the bluegrass area population and 5.8% for the alfalfa area population. The proportions of aggressive types for M. pennsylvanicus populations in bluegrass and prairie habitats did not vary significantly with phase of the population cycle and there was no indication of an increased level of individual aggressiveness at peak densities. Phase of cycle explained 25.2% of the variation in behavioral data for the bluegrass area population and 12.2% for the prairie population. Seasonal heterogeneity was found in the behavior of M. ochrogaster and season accounted for more of the behavioral variation in each population than had phase of cycle. Although seasonal trends were not entirely consistent, the data suggested that males may be more aggressive in winter and autumn. For M. pennsylvanicus the proportions of nonaggressive males were lower during spring and autumn (which correspond to the breeding seasons) than during summer and winter. The results of the present study were not consistent with the polymorphic behavior hypothesis.
Density and microdistribution of chironomid larvae in an Alberta brown-water stream
Authors: Boerger Hans J. , Clifford Hugh F. , Davies Ronald W.
Published: August 2008

Seasonal changes in density of chironomid larvae were examined in nine microhabitats in a small, slow-flowing stream draining muskeg terrain. During July and August aquatic macrophytes increased the area available for colonization by chironomids 5- to 10-fold, but harbored only 30–40% of the total density of 20 000–52 200 larvae m−2 of stream surface. In the sediment mean density was 19 900 larvae m−2 and varied 17-fold over a 23-month period. Minimum and maximum densities were reached in June and March, respectively. During May–August mean densities on Sparganium, Potamogeton, Hippuris, submerged moss, sponge colonies, and filamentous algae were 93, 171, 466, 978, 32, and 35 larvae per gram dry weight, respectively. Larval densities on annual aquatic macrophytes increased during the course of the summer and reached highest values on those macrophytes with the greatest surface area: weight ratio. Mean density on submerged wood was 16 larvae cm−2. Two-thirds of the 32 most abundant species were found primarily on only one of the nine microhabitats. The number of species found specifically in one microhabitat was 13 for sediment, 3 for moss, 2 for Sparganium, 1 each for Potamogeton, Hippuris, filamentous algae, and wood, and none for sponge and autumn-shed leaves.
Nest usurpation and sequential nest occupation in the digger wasp Crabro monticola (Hymenoptera: Sphecidae)
Authors: Alcock John
Published: August 2008

Females of Crabro monticola regularly abandoned the nests which they had been provisioning, sometimes for no apparent reason, sometimes because the nest had been entered in their absence by a conspecific usurper. After giving up her nest, a female had the option of digging a new nest or entering an already constructed burrow and usurping it from its owner, if it were occupied. Both options were exercised by members of the population. The result was that individual nests were held by as many as six different females over the course of 26 days. Each female occupied 2.2 nests on the average during the study. The adaptive advantages of nest usurpation and burrow switching are unclear. Nest usurpation attempts never resulted in joint occupation of a burrow in this species. Therefore, whatever its benefits, the entering strategy can evolve even if it does not lead to joint defense of a nest by its "communal" occupants.
Infestations of Piagetiella peralis (Mallophaga: Menoponidae) on juvenile white pelicans
Authors: Samuel W. M. , Williams E. S. , Rippin A. Blair
Published: August 2008

Seventy-four of 76 juvenile white pelicans, Pelecanus erythrorhynchus, of Primrose Lake, western Saskatchewan, were infested with the chewing louse Piagetiella peralis. Ulcerative lesions were common on the body of naked birds approximately 1 week of age and in the throat pouches of older juveniles (2–7 weeks old); 20 of 47 older juveniles were severely infested. Prevalence and pathology are described for several age-classes of juvenile pelicans.
Lubricants reduce fission of the planarian flatworm (Dugesia tigrina) (Girard)
Authors: Amelsvoort Gemma van , George John A.
Published: August 2008

Vaseline petroleum jelly applied to the substrate was found to be the most effective of five lubricants tested in reducing asexual reproduction (fission) in the planarian flatworm Dugesia tigrina (Girard). Planarians which did not bud attained a much greater size than untreated controls.
Shallow-water epilithic invertebrate communities of eastern Georgian Bay, Ontario, in relation to exposure to wave action
Authors: Barton D. R. , Carter J. C. H.
Published: August 2008

The effects of exposure to wave action on the composition of shallow-water, epilithic invertebrate communities in eastern Georgian Bay were examined in May and July 1979. Samples were collected from stations which differed in depth (0–4 m), aspect, and type of underlying bedrock (granite or limestone). An index of exposure was calculated for each station based on fetch, proportion of winds in the previous month blowing toward the shore, and depth. Axis 1 derived from principal components analysis also ranked the stations in order of degree of exposure to wave action. Total abundance of invertebrates tended to decrease with increasing degree of exposure except at the most exposed stations in July where large numbers of two chydorid species were found. Number of taxa per site declined with increasing exposure in both months. There was no clear difference in the response to exposure between communities on granite and limestone. Dominant organisms included Copepoda, Chydoridae (Cladocera) (especially in July), Naididae (Oligochaeta), and Chironomidae (Diptera). The total abundance of invertebrates on bedrock was similar to values reported from mud and sand in other lakes.
Effect of pulse pressure on fluid exchange between blood and tissues in trout gills
Authors: Davie Peter S. , Daxboeck Charles
Published: August 2008

Clearance of ethanol from gill tissues was measured during both pulsatile and nonpulsatile perfusion in an isolated saline-perfused trout head preparation. Pulsatile perfusion increased the rate of ethanol clearance from the respiratory tissues. Compartmental analysis of ethanol washout curves indicated that ethanol clearance during pulsatile perfusion was increased principally by more rapid exchange of ethanol between slow (tissue) and fast (vascular) compartments. Analysis of fluid movements between blood and tissues showed that 25–45% of the total flux could pass from blood to tissues and back within each beat of the heart. This dynamic component represents a previously overlooked paracellular pathway for exchange of water and solutes which is dependent upon pulsatile vascular pressures.
Morphological variation in Romanomermis culicivorax Ross and Smith, 1976 (Nematoda: Mermithidae)
Authors: Curran J.
Published: August 2008

The morphological characters lateral chord structure, head, tail, vagina and spicule shape, which are those most frequently used in the diagnosis of mermithid species, were highly variable within the progeny of a single mating pair of Romanomermis culicivorax Ross and Smith, 1976. In the light of this variability the usefulness of these characters in species diagnosis is discussed and it is concluded that a series of specimens at various developmental stages are required for reliable diagnosis.
Flock formation in white pelicans
Authors: O'Malley J. Brian E. , Evans Roger M.
Published: August 2008

White pelicans travel between breeding colonies and distant foraging sites in flocks. We described the process of flock formation during departures from colonies at East Shoal Lake, Manitoba. Interdeparture intervals in 1978 and 1979 were significantly clumped, which suggests individual white pelicans follow one another when initiating foraging trips.Flocks increased in size and made increasing use of air thermals as they travelled toward foraging areas. Flocks were most common and most variable in size between 1145 and 1345. Flock size was stable over the season, while the number commuting each day increased geometrically to a maximum by the end of the nestling period.Flocks observed near the colonies were characterized by low, horizontal, flap-gliding flight. Further enroute they flew higher and showed greater frequencies of gliding and ascending flight associated with increasing use of thermals.Our results provide no support for the view that colonies and flocks represent manifestations of functional information centers. The results are in agreement with the alternative interpretation that colonies and flocks facilitate group foraging and permit effective use of local enhancement as a means of locating thermals.
Ramellogammarus vancouverensis Bousfield (Amphipoda) as an intermediate host for salmonid parasites in British Columbia
Authors: Margolis L. , Moravec F.
Published: August 2008

Larvae of the nematode Salvelinema walkeri (Ekbaum, 1935) and metacercariae of the trematode Crepidostomum metoecus (Braun, 1900) are recorded for the first time from the amphipod Ramellogammarus vancouverensis Bousfield, 1979 (Amphipoda: Gammaridae).The infected amphipods were collected from De Mamiel Creek, southwestern Vancouver Island, British Columbia. Brief descriptions are given of both parasites, which as adults live in salmonid fishes. This report provides the first record of an intermediate host for S. walkeri, a swim-bladder parasite of salmonids of the Pacific region of North America, and of an intermediate host of a Crepidostomum species in the Pacific region of Canada.
Transepithelial ion transfer processes as mechanisms for fish acid–base regulation in hypercapnia and lactacidosis
Authors: Heisler N.
Published: August 2008

In fish, the respiratory acidosis resultant from environmental hypercapnia is generally compensated by bicarbonate accumulation in intracellular and extracellular body compartments. The additional bicarbonate is partially produced by nonbicarbonate buffering, but primarily gained from the environment via rate-limited ion transfer mechanisms, which apparently are dependent upon certain environmental factors. During lactacidosis resultant from strenuous exercise the majority of produced H+ ions is initially buffered intracellularly, until they are transiently transferred via ion exchange mechanisms to the environment. After normalization of the acid–base status (at still high intracorporal lactate levels) H+ ions are gradually recovered from the water for further aerobic processing of lactic acid.In both types of acid–base disturbances, ion exchanges effective for the acid–base status are primarily performed via the branchial epithelium. The role of the fish kidneys is usually small; skin and other excretory sites contribute only insignificantly.Branchial transfer of surplus H+ ions by fish to the environment appears to be a very common and probably the most important mechanism utilized to cope with severe acid–base disturbances, thereby mitigating against the effects of adverse environmental conditions on their "milieu interieur."
Cardiovascular changes in the rainbow trout (Salmo gairdneri Richardson) during exercise
Authors: Randall D. J. , Daxboeck C.
Published: August 2008

The effects of steady-state, aerobic swimming exercise upon the cardiovascular system of rainbow trout (Salmo gairdneri) are discussed. When these fish are forced to swim at 80% of their critical velocity, blood flow is redistributed in the systemic circulation to favour working muscles, at the expense of decreased flow to nonmuscle structures. Given oxygen uptake and cardiac output data, combined with blood flow distribution patterns during exercise, it is calculated that the working muscles can account for nearly all the measured increase in total oxygen uptake at this level of exercise. The possible underlying mechanisms for systemic blood flow control and the increase in gas exchange efficiency across the gills of exercising rainbow trout also are examined.
Gill ventilation, gas exchange, and survival in the Atlantic mackerel (Scomber scombrus L.)
Authors: Holeton G. F. , Pawson M. G. , Shelton G.
Published: August 2008

The hypothesis that mackerel are dependent on ram ventilation for adequate gas exchange is disproved by experiments in which oxygen tensions and concentrations, pH, and carbon dioxide concentrations are measured in arterial blood. No significant differences are found in blood samples taken from swimming and nonswimming animals in a swim tunnel. The latter show active breathing movements of the type usually encountered in teleosts. Mackerel held either in the swim tunnel or in a large storage tank are able to restore plasma lactate levels to normal, even after procedures to cannulate the dorsal aorta or the severe trauma of being caught in a trawl. Such fish do, however, show a colour change from yellow to blue, an increased permeability to sodium ions, and evidence of considerable integumental damage. Abrasion of an extremely delicate integument is more likely to be the primary cause of death in mackerel held at high densities in nets or in other situations than is a failure of the gas exchange process and the accumulation of metabolic products such as lactic acid.
The amphibian carotid labyrinth: some anatomical and physiological relationships
Authors: Toews Dan , Shelton Graham , Boutilier Robert
Published: August 2008

The carotid labyrinth of 13 different amphibian species were examined using a vascular casting technique. Only Typhlonectes compressicauda, an apodan, and Necturus do not have a labyrinth although members of the lungless Plethodontidae have a very reduced labyrinth vascular network. Blood pressures recorded in the internal carotid, external carotid, and common carotid arteries of freely moving Bufo marinus and Rana catesbeiana show that the labyrinth does not affect a pressure change or have a pulse dampening effect on blood flowing to the head region. It is suggested that the labyrinth can stimulate a [Formula: see text] increase in the internal carotid artery in Bufo and Rana although the underlying mechanism remains unknown.
Development of Turgida turgida (Rudolphi, 1819) (Nematoda: Physalopteroidea) in the opossum (Didelphis virginiana)
Authors: Gray J. B. , Anderson R. C.
Published: August 2008

Opossums given infective larvae of Turgida turgida were examined at various times after infection. Fifteen days after inoculation 13% of larvae recovered were undergoing the third moult. Thirty-five days after infection 20% of larvae found were moulting to the adult stage. The prepatent period was 89–105 days and the life span of worms was at least 360 days. The percentage of the inoculum recovered decreased with time. Also, development was asynchronous; i.e., third-, fourth-, and fifth-stage worms were found in individual opossums examined 40 and 160 days after infection. Second- and moulting second-stage larvae were not infective to opossums. Infections were successfully challenged. Attempts to infect cats (Felis catus), raccoons (Procyon lotor), and woodchucks (Marmota monax) were unsuccessful.
Aspects of the biology of Mysis mixta (Lilljeborg 1852) (Crustacea, Mysidacea) in New Hampshire coastal waters
Authors: Grabe Stephen A. , Hatch Elizabeth R.
Published: August 2008

Mysis mixta spawned from December to April in coastal New Hampshire waters. Females outnumbered males throughout all but the earliest dates of the spawning period. Average clutch size was 60 eggs or larvae. Juveniles were hyperbenthic during the day and migrated into the water column at night. Juveniles remained in inshore waters until surface water temperature s exceeded 12 °C, corresponding with the onset of thermal stratification. Juvenile growth was slow through mid-April then increased sharply from late April through June. Less than 5% of the population appeared to live longer than 1 year.
Early winter food habits of Manitoba moose as determined by three rumen analysis methods
Authors: Zach R. , Crichton V. F. J. , Stewart J. M. , Mayoh K. R.
Published: August 2008

Early winter food habits of moose (Alces alces) from Hecla Island and Manitoba game hunting area 26 in southeastern Manitoba were studied in 1978 and 1979. Twenty-five plant taxa were identified in 86 rumen samples. In decreasing order of importance, moose fed mainly on red-osier dogwood (Cornus stolonifera), balsam fir (Abies balsamea), willow (Salix spp.), mountain maple (Acer spicatum), trembling aspen (Populus tremuloides), bog birch (Betula glandulifera), and balsam poplar (Populus balsamifera). These taxa constituted about 98% of the diet by weight. Most rumens contained several of these taxa, with some containing traces of the uncommon ones. The diet of moose from the two study areas was similar, but Hecla Island moose showed a shift in diet from 1978 to 1979. The diet was not influenced by sex or age of the moose.Three methods of food habit determination were used: presence/absence, abundance score, and dry weight. All three methods yielded very similar results. Although some rumen samples had a volume of only 0.13 L, sampling volume was not significantly correlated with the number of taxa identified per sample. Gains curves showing the cumulative total number of taxa versus successive samples collected indicated that the number of samples analyzed was adequate.
Thyroid function in fed and fasted white-tailed deer fawns
Authors: Watkins B. E. , Nachreiner R. F. , Schmitt S. M. , Cooley T. M. , Ullrey D. E.
Published: August 2008

Serum thyroid hormone concentrations and thyroxine (T4) kinetics were determined in three fed and two fasted white-tailed deer fawns (Odocoileus virginianus borealis). Fasting for 16 days resulted in a drastic decline in total triiodothyronine (T3) (3.22 to 0.49 ng/mL), T4 (241.6 to 68.3 ng/mL) and, to a lesser extent, free T4 (FT4) (2.59 to 1.37 ng/dL). Reverse T3 (rT3) did not change significantly. Although T4 secretion rate (TSR) was greatly reduced (P < 0.05) in the fasted fawns (2.5 (fasted) versus 10.5 (fed) μg T4 per body weight 0.75 (in kilograms) after 20 days of fasting), fractional turnover rate (k/day), total distribution volume (TDV), and metabolic clearance rate (MCR) of injected [131I]T4 did not differ significantly from values in fed fawns. Serum thyroid hormone profiles of the fasted fawns were similar to those reported previously in wild deer collected in Michigan during late winter. In contrast, however, there was no indication of thyroid enlargement.
An age-dependent response to synthetic salmon calcitonin in the chuckwalla, Sauromalus obesus
Authors: Kline L. W.
Published: August 2008

Injection of synthetic salmon calcitonin (25 mU) stimulated a decrease in the plasma calcium levels in young intact lizards, Sauromalus obesus. The same dose of synthetic salmon calcitonin had no effect on older intact lizards. A dose twice the original also had no effect in older intact lizards. This indicates an age-dependent response.
Classification of the behavior of sea otters (Enhydra lutris)
Authors: Packard J. M. , Ribic C. A.
Published: August 2008

In an instantaneous sample of animal behavior, an observer must reliably recognize a behavioral unit. Previously, quantitative studies of sea otter behavior have used broadly defined activity states as behavioral units (e.g., feeding, resting, grooming, interaction, locomotion). However, an action pattern observed in an instantaneous sample may occur in the context of several different activity states. This study defines 43 discrete action patterns on the basis of form and examines natural clusters based on time sampling of focal animals. Overlap in the action patterns occurring during activity states classified by observers was determined. The possibility of using objective mathematical criteria to classify samples was examined by discriminant analysis of focal animal samples. The activity states of resting and feeding appeared sufficiently distinct to be reliably recorded during instantaneous sampling. However, there was more overlap in action patterns recorded during grooming, interaction, and locomotory activity.
Determination of the number of instars and size variation in the larvae and pupae of Simulium chutteri Lewis 1965 (Diptera: Simuliidae) and some possible bionomical implications
Authors: Moor F. C. de
Published: August 2008

Morphometric studies show that there are seven larval instars in Simulium chutteri. A guide for separating instars of S. chutteri is included. Seasonal and sexual size variation and seasonal variation in biomass in larvae and pupae of S. chutteri are statistically analysed and discussed. Water temperature is a major factor in determining larval and pupal size variation and duration of the pupal stage. Growth in S. chutteri follows a geometric pattern and is in agreement with previous works on other species. An overlap of larger and smaller larvae at the same developmental stage resulted from the coexistence of early winter and late summer generations, respectively. Larger larvae and pupae can result in autogenous and more fecund adult females. This is important in the population dynamics of this pest species and can lead to sudden unexpected population explosions. It is suggested that population explosions could be controlled by sharply reducing the population of large individuals of S. chutteri in the spring.
Aethycteron n.g. (Monogenea: Ancyrocephalinae) from darters (Percidae: Etheostomatini) in Ontario, Canada with descriptions of A. caerulei n.sp., A. micropercae n.sp., and A. nigrei n.sp. from Etheostoma spp.
Authors: Suriano D. M. , Beverley-Burton M.
Published: August 2008

Aethycteron n.g. is proposed for ancyrocephaline monogeneans from darters (Percidae: Etheostomatini): penis enfolded by spiralling sheath incorporating two filaments; accessory piece attached to penis sheath; dorsal and ventral hamuli of similar shape; marginal hooks of similar shape and size. Aethycteron malleus (Mueller, 1938) n.comb. is designated as type species and is redescribed from the present material as is A. moorei (Mizelle, 1940) n.comb. and A. hargisi (Hanek and Fernando, 1972) n.comb. Aethycteron caerulei n.sp., A. micropercae n.sp., and A. nigrei n.sp. are proposed. Aethycteron nigrofasciatus (Harrises, 1962) n. comb., A. ammocryptus (Harrises and Vickery, 1970) n. comb., A. chlorosomus (Harrises and Vickery, 1970) n.comb., A. lottensis (Harrises and Vickery, 1970) n. comb., and A. stigmaeus (Harrises and Vickery, 1970) n.comb. are transferred from Urocleidus Mueller, 1934, the generic diagnosis of which was emended by Suriano and Beverley-Burton in 1981.
Susceptibility of the leech Batracobdella picta (Verrill) to Trypanosoma andersoni Reilly and Woo and Trypanosoma grylli Nigrelli (Kinetoplastida)
Authors: Reilly Brian O. , Woo P. T. K.
Published: August 2008

Laboratory-raised grey tree frogs, Hyla versicolor LeConte, infected with either Trypanosoma andersoni Reilly and Woo or Trypanosoma grylli Nigrelli were fed on by laboratory-raised leeches, Batracobdella picta (Verrill). Trypanosoma andersoni multiplied by binary fission as sphaeromastigotes and epimastigotes in the gut of B. picta at 22 ± 1 °C. Some sphaeromastigotes and epimastigotes contained yellow granules. Two types of metatrypanosomes were found in the digestive tract of the leech at 24 days. Trypanosomes from leeches which had infected blood meals 35 days earlier were not infective when inoculated intraperitoneally or by the leeches feeding on laboratory raised H. versicolor. Trypanosoma grylli did not develop in B. picta at 22 ± 1 °C
Fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in the northeast Pacific Ocean
Authors: Beacham Terry D.
Published: August 2008

Significant regional and annual variability in fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in British Columbia was detected during this investigation. A Kodiak Island (Alaska) coho salmon stock was more fecund than southern stocks in British Columbia and Washington. Fecundity ranged from 2450 to 2850 eggs per female at 53.6 cm postorbital–hypural length for Vancouver Island stocks to over 4400 eggs per female for a Kodiak Island stock at the same length. Chum stocks on Vancouver Island and the Queen Charlotte Islands generally had fecundities less than 3200 eggs per female at 58.8 cm postorbital–hypural length, whereas chum of equal lengths in mainland British Columbia stocks ranged from 3200 to 3450 eggs per female. Older chum and coho were usually more fecund than younger ones, but this difference could be accounted for by differences in mean length-at-age, fecundity being related to body size.