bluuebunny/crossref_metadata_2025 huggingface dataset:
The life history of Diastylis sculpta Sars, 1871 (Crustacea: Cumacea) in Passamaquoddy Bay, New Brunswick
Authors: Corey Susan
Published: August 2008

Diastylis sculpta was collected from shallow water (1–15 m) in Passamaquoddy Bay over a 26-month period. D. sculpta produces a rapidly growing and developing summer generation between two successive winter generations. The overwintering generation releases young in mid-July and late August. The summer generation releases young in November. The mean fecundity of the summer-gravid females (78.4) is much greater than the mean fecundity (20.0) of the fall-gravid females. The maximum life-span is 5 months and 12 months for members of the summer and winter generations respectively.
The development and pathogenesis of Leucocytozoon simondi in Canada and domestic geese in Algonquin Park, Ontario
Authors: Desser Sherwin S. , Ryckman Andrée K.
Published: August 2008

The development of Leucocytozoon simondi was studied in naturally and experimentally infected Branta canadensis maxima, Branta canadensis interior, and Anser domesticus. The number of mature round gametocytes in the peripheral blood of the Canada geese increased between days 9 and 15 post exposure (PE) and decreased rapidly thereafter. Mean peak parasitemias recorded on day 13 PE were (per 1000 red blood cells (RBC)): 8 gametocytes in B.c. maxima, 16 gametocytes in B.c. interior, and 17 gametocytes in A. domesticus. About 3 weeks PE, gametocytes disappeared from the peripheral circulation and were not observed again during the autumn, winter, and spring in birds kept in the laboratory.Haematocrit determinations in the Canada geese revealed a low fluctuating anemia during the primary infection which subsided by day 21 PE. A more severe anemia was recorded in A. domesticus with a mean low packed RBC value of about 18% on day 11 PE. Immature and mature hepatic schizonts were observed in the Canada and domestic geese between days 3 and 8 PE. Neither megaloschizonts nor elongate gametocytes were seen. Clinical signs, pathology, and mortality commonly associated with L. simondi infection in ducks were not observed. Hypotheses are advanced to explain reports of severe pathogenesis associated with L. simondi infections in Canada geese in other localities.
Evolution of the subgenus Cyphelophorus (Genus Helophorus, Hydrophilidae, Coleoptera): description of two new fossil species and discussion of Helophorus tuberculatus Gyll.
Authors: Matthews Jr. John V.
Published: August 2008

Exposures of late Tertiary sediments in the North American Arctic contain well-preserved fossils of Coleoptera (beetles). Two sites, Lava Camp in western Alaska and locality 2-73 on Meighen Island (Canadian Arctic Archipelago), have yielded fragments referable to two fossil species of the helophoran subgenus Cyphelophorus (Hydrophilidae). The only extant species in the subgenus, Helophorus tuberculatus Gyll., is characterized by a distinctive array of elytral tubercles, the intraspecific variation of which is documented here as an aid for distinguishing H. tuberculatus from the two fossil species.The two fossil species are obviously related to H. tuberculatus and probably represent sequential species in the lineage leading to H. tuberculatus. If so, they provide information on evolutionary trends within the Cyphelophorus lineage, and when examined in the light of the morphological features of species in other Helophorus subgenera, show that the tuberculate elytron seen in H. tuberculatus is probably a derived character that developed by modification of an elytron initially having raised alternate interstices.
A protostrongylid nematode (Strongylida: Protostrongylidae) in woodland caribou (Rangifer tarandus caribou)
Authors: Lankester M. W. , Crichton V. J. , Timmermann H. R.
Published: August 2008

First-stage protostrongylid larvae found in faeces of woodland caribou (Rangifer tarandus caribou) in northwestern Ontario and Manitoba may be larvae of Elaphostrongylus sp., a well-known agent of neurologic disease in reindeer (Rangifer tarandus tarandus) of Eurasia.
Acetylcholinesterase and synapses in the nervous system of Phocanema decipiens (Nematoda): a histochemical and ultrastructural study
Authors: Goh S. L. , Davey K. G.
Published: August 2008

The nervous system of Phocanema decipiens was examined histochemically for acetylcholinesterases (EC 3.1.1.7) using the acetylthiocholine method with specific inhibitors (eserine and diisopropylfluorophosphate) and different substrates (butyrylthiocholine and acetylthiocholine). The enzymes, which are localized mainly as small discrete granules, are found in the nerve ring, the six longitudinal nerve cords, and the three pharyngeal nerves. With the electron microscope, these neurons are found to contain presumptive cholinergic synaptic contacts with aggregations of small lucent vesicles in the presynaptic axons. In the nerve ring, such synapses are observed in axoaxonal, neuromuscular and axoglial cell contacts. The longitudinal nerve cords have neuromuscular junctions similar to those observed in other nematodes. In the four sublateral nerve cords, the alternating regions with and without synaptic contacts correspond to the discontinuous histochemical pattern of enzymatic activity. The pharyngeal nerves have axoaxonal and axooesophageal musculature synapses. In most of the synapses, some large dense or dense-core vesicles are found intermingled with the small lucent vesicles. This coexistence of different vesicles is discussed in the light of the cholinergic link hypothesis, whereby acetylcholine is initially released to facilitate the release of other neurotransmitters.
Bioenergetics of the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae)
Authors: Campbell A. , Singh N. B. , Sinha R. N.
Published: August 2008

Cumulative energy budgets were determined for the immature and adult stages of Sitophilus granarius (L.) reared on single wheat kernels, Triticum aestivum L. Caloric values (cal/mg dry weight) for S. granarius stages reared at 30 °C and 70% relative humidity (RH) were 5.792 for eggs, 5.989 for third-instar larvae, 6.474 for prepupae, 5.985 for pupae, and 5.975 for adults. Larval production increased exponentially from 0.13 cal in early first-instar larvae to 12.0 cal for 20-day-old fourth-instar larvae and prepupae, and declined to 6.9 cal during the pupal stage.To complete development larvae consumed a mean 62.6% of a 126-cal kernel, whereas an average adult consumed over 3.5 times more than the total larval consumption. Assimilation efficiencies for larval development were similar (73.9 to 76.2%) at three temperatures, 20, 25, and 30 °C. Of energy consumed during larval and pupal development, 65.7% was explained by respiration. Net production efficiency was 20% for all larval stages and 48% for total egg production by an adult.
Quantitative and aesthetic factors in the definition of an ideal environment
Authors: Hayes F. R.
Published: August 2008

Environmental idealism is rooted in our Western religious traditions, according to which the quality of our surroundings has fallen, because of our sins, from some Garden of Eden ideal to its present deplorable state. Through our faith and work it is eventually to be redeemed to new glory (formerly only in Paradise, now thought to be awaited in this world).By contrast, measurements on the environment, based on scientific realism, approach the ideal by stages, the simplest being the notion of death as exemplified in the pioneer "limiting factors" approach of A. G. Huntsman. Today's examples include, among other things, the monitoring of air and water as pollutants.Experiments by F. E. J. Fry led him to replace the negative idea of lethal factors with the positive concept of "scope for activity." Extension of the latter idea, when applied to the human environment, brings in consideration of the "quality of life," which is associated, on this continent, with the name of Ian L. McHarg. It has brought with it, multidisciplinary measurements that lead to the planned division of a large area, say a river valley, into zones for optimal distribution of man's activities.Thus a beginning is made of reconciliation between the humanistic vision and the age of realism. The possibilities of developing a unified system are discussed.
A photosensitive daily rhythm in the female medaka, Oryzias latipes
Authors: Chan Kenneth Ka-Sing
Published: August 2008

Adult female medaka, Oryzias latipes, with regressed ovaries were exposed to 7 h of continuous light plus an additional hour of light at different times during the dark period of a 24-h cycle (7 + 1 light: 16 dark) at 24 ± 1 °C. When this additional hour of light falls on the 16th h, counting the onset of the light period as the 0 h, ovarian development was induced. This ovarian development is enhanced when the exposure period is increased and when the fish are preexposed to a warm temperature. The use of a photosensitive daily rhythm to measure photoperiod and to time the spawning season in the medaka is suggested.
Enhanced competence in the negotiation of a T maze by Drosophila melanogaster in response to a possible food reward
Authors: Threlkeld S. F. H. , Bentley L. , Yeung A. , Henriksen K.
Published: August 2008

Starved Drosophila melanogaster were run individually in a T maze in which sucrose was provided as a reward. After three trials, flies were run similarly for a fourth trial in a clean maze lacking sucrose. The time in which the food area was located in the fourth trial compared with the first was significantly decreased. Control experiments rule out the possibility that smell. pheromones, or increased energy levels associated with the ingestion of sucrose are the basis of the highly significant differences. A likely alternative is that the flies to some degree learn the location of the food area.
Reproductive behaviour and physiology of Tenebrio molitor (Coleoptera: Tenebrionidae). III. Histogenetic changes in the internal genitalia, mesenteron, and cuticle during sexual maturation
Authors: Gerber G. H.
Published: August 2008

The histogenic changes in the internal genitalia and mesenteron and the hardening and darkening of the cuticle during the first days of adult life in Tenebrio molitor L. are described. At emergence, the testes contain mature spermatozoa and the ovaries possess small oocytes. During the first 3 days, the shape, size, appearance, and staining characteristics of the secretory cells of the lateral oviducts, female accessory gland, tube accessory glands, bean-shaped accessory glands, and glandular region of the vasa deferentia change. Similar changes were not seen in the seminal vesicles and spermatheca. All of the secondary sex glands are filled with secretion by day 4. In the midgut, changes occur in the size, shape, and appearance of the epithelial cells by the 3rd day, and a peritrophic membrane is secreted during days 2 and 3. Most adults do not begin to feed until after the 3rd day. By day 3, the hardening and darkening of the cuticle are completed. All of these changes clearly are associated with adult maturation, especially sexual maturation, and most or all of the them must take place before the adults are able to copulate and oviposit.
On the reliability of enumeration for mark and recapture census of voles
Authors: Hilborn Ray , Redfield James A. , Krebs Charles J.
Published: August 2008

Some studies of populations in small rodents rely on enumeration of individuals to provide an estimate of population size. A computer simulation of the capture–recapture process was used to examine the influence of five population parameters on the reliability of enumeration. Enumeration is shown to be insensitive to population size, survival between sampling intervals, and individual variation in the probability of capture. Enumeration is sensitive to the probability of capture; if the probability of capture for the average individual falls below 0.5, the enumeration technique provides a poor estimate of population size. Enumeration is also extremely sensitive to reduced probabilities of capture for unmarked animals. Data from capture–recapture studies of five species of Microtus were used in the computer simulation, and it was concluded for these five species that enumerated populations are at least 10–20% smaller than the actual populations.
The anesthesia of the lobster (Homarus americanus) by isobutanol injection
Authors: Gilgan M. W. , Burns B. G.
Published: August 2008

The lobster, Homarus americanus, can be quickly and reproducibly anesthetized by the injection of small amounts of isobutanol (2-methyl-1-propanol) into the abdominal sinus. The minimum effective (100%) isobutanol dose was lower when the lobsters were held in 15 °C seawater (1.0 μl per 10 grams live weight) than when they were held at 6.0–8.5 °C (2.0 μl/10 g). However, anesthesia at the lower temperature was safer (therapeutic index (T.I.) about 40) than at 15 °C (T.I. about 30) and the anesthesia could be much more sustained (184 min) with complete safety.
Biogeography of the Jaera albifrons superspecies (Isopoda, Asellota) on the Atlantic coast of Canada
Authors: Veuille Michel
Published: August 2008

The biogeographical study of the four Canadian forms of the Jaera albifrons superspecies leads to a division into two groups. J. (a.) albifrons, J. (a.) ischiosetosa, and J. (a.) praehirsuta are spread along the whole Atlantic coast, from cold to temperate shores but, as in Europe, salinity and exposure affect their relative abundance. J. (a.) posthirsuta occurs only in the warm shallow waters protected from arctic currents. The presumably postglacial origin of its disjunct distribution is discussed.
Bird populations in the Kluane Mountains, southwest Yukon, with special reference to vegetation and fire
Authors: Theberge John B.
Published: August 2008

Bird populations were studied in relation to vegetation communities in the Kluane Ranges, Yukon. Information on species diversity and abundance was collected on 39 linear 4-ha plots in eight communities by noting birds heard and seen on repeated walks over each plot. Bird populations in tundra and subalpine communities were dissimilar from the six lowland communities, the latter all showing a marked similarity (lowland willow shrub, upland willow shrub, spruce–poplar forest, mature spruce, riparian poplar forest, balsam poplar parkland). Communities with greatest species diversity also had greatest total abundance. The tundra ranked lowest in diversity and abundance. Subalpine, however, held a high number of species, reflecting its ecotone position. Subalpine was distinctive in having few species of intermediate density compared with the density–dominance structure of birds in the other communities. The close similarity between bird populations in the lowland communities, despite distinctive differences in vegetation species and structure, was due to the overriding presence of three species that remained abundant throughout succession: dark-eyed junco, Swainson's thrush, and yellow-rumped warbler, which means that species not closely specialized to the vegetation predominate over most of the region.
Den-site characteristics of arctic coastal grizzly bears (Ursus arctos L.) on Richards Island, Northwest Territories, Canada
Authors: Harding Lee E.
Published: August 2008

Winter den sites of grizzly bears (Ursus arctos L.) were examined during summer, 1973, and spring, 1974, and 1975. The purpose was to locate denning areas and estimate the number of bears on Richards Island, N.W.T., and to assess the importance of soil, landform, and other characteristics that determine the suitability of sites for denning. A total of 23 dens was examined. Dens were situated in river or lake banks, in Pleistocene uplands, in silty or sandy soil, and frequently with a south exposure. Density was one bear per 106 square kilometres to one per 175 square kilometres.
The emergence of cercariae of Trichobilharzia ocellata and its relationship to the activity of its snail host Lymnaea stagnalis
Authors: Anderson P. A. , Nowosielski J. W. , Croll N. A.
Published: August 2008

The emergence pattern of cercariae of Trichobilharzia ocellata from Lymnaea stagnalis was examined at 2-h intervals from infected snails acclimatized to 12 h light – 12 h dark periods. A marked diel pattern of emergence was found during the periods of illumination; this was reversed when the light–dark regime was reversed.A method for the continuous recording of the locomotory activity of L. stagnalis is described. Snails acclimatized to either normal or reversed dark–light regimes showed a consistent diel pattern of activity during illumination. Peak activity occurred in the first few hours of illumination.It is proposed that the diel activity pattern results from an internal rhythm in which the snail becomes entrained to the lighting regime. The close association between the diel activity pattern of the snail and the emergence of T. ocellata indicates that host movement stimulates cercarial emergence. Light is thought to influence the cercariae directly and indirectly through the snail.
On the development of chicken adenohypophyseal melanophore-expanding activity
Authors: Betz T. W. , Enemar Anders , Röhss Michael
Published: August 2008

Melanophore-expanding activity (MEA) was detectable at least by stage 30 of Hamburger and Hamilton (6–6.5 incubation days) in 53 whole adenohypophyseal anlagen (plus mesenchyme) from domesticated Gallus gallus embryos. This was estimated from responses to adenohypophyseal implants next to dermal melanophores of intact Rana temporaria tadpoles, as compared with control implants of embryonic myelencephalic tissue. Analyses of 27 implants of adenohypophyseal cephalic- or caudal-region tissue alone indicated that MEA was associated mostly with cephalic regions. This association started at least by stage 35 (8–9 incubation days) and continued until the 1st day post hatching, as compared with control implants of embryonic eyelid tissue.
Eléments minéraux du régime alimentaire du campagnol des champs, Microtus pennsylvanicus (Ord.)
Authors: Bergeron Jean-Marie
Published: August 2008

One hundred and ninety-five meadow voles, Microtus pennsylvanicus (Ord.) were captured by means of 485 traps installed each month during the summer of 1974 in four types of culture. The analysis of minerals in their diet indicates low variation in potassium levels, whereas nitrogen, calcium, phosphorus, and magnesium levels appear to be much more environment-dependent. There are a few differences between the diets of males and females. Stomach contents of captured voles do not vary significantly from one type of culture to another, but the physiological reproductive condition of the animals accounts for significant differences in stomach contents.[Journal translation]
Predation of ringed seal pups (Phoca hispida) by the arctic fox (Alopex lagopus)
Authors: Smith Thomas G.
Published: August 2008

The arctic fox (Alopex lagopus), commonly assigned the role of scavenger of marine mammal remains left by polar hears (Ursus maritimus), is for the first time quantitatively described as an important predator of the pups of the ringed seal (Phoca hispida). Foxes enter and kill the seal pups in their subnivean birth lairs. In no case were any seals other than pups killed by foxes. While predation was seen to vary over the 3 years of study, an average pup predation of 26.1% in nearshore sea ice is estimated. Estimates of the contribution of seal pups to the fox energy budget are calculated. Newborn seal pups contribute a maximum of 45.2 and a minimum of 30.2 days of maintenance energy. Almost weaned pups provide a maximum of 341.5 and a minimum of 227 days of maintenance energy.
Description of a new species of pontellid copepod, Anomalocera opalus, from the Gulf of St. Lawrence and shelf waters of the Northwest Atlantic Ocean
Authors: Pennell William M.
Published: August 2008

A new species of pontellid copepod, Anomalocera opalus, is described from the Gulf of St. Lawrence and shelf waters of the western North Atlantic. A new anatomical structure is described that enables this species to attach itself to the sea surface. The distribution of the new species is given.
Pesticide dynamics in robins nesting in contaminated and uncontaminated forests in northern Maine
Authors: Knupp D. M. , Owen Jr. R. B. , Dimond J. B.
Published: August 2008

The pesticide dynamics in robin (Turdus migratorius) populations nesting in DDT-contaminated and uncontaminated forests in northern Maine were investigated between 1966 and 1973. About 25% of a female's pesticide load passed into each clutch of eggs. Adults nesting in uncontaminated areas lost about 87% of their pesticide load by August, and there was a significant decrease in pesticide levels from eggs to fledglings. Adults nesting in contaminated areas exhibited no loss of pesticide during the reproductive season and residue levels increased from eggs to fledglings. No eggshell thinning or egg mortality was noted.
External morphology of sensilla on the legs of selected black fly species (Diptera: Simuliidae)
Authors: Sutcliffe James F. , McIver Susan B.
Published: August 2008

The sensilla on the legs of four simuliid species, S. rugglesi, S. arcticum, S. baffinense, and S. euryadminiculum were described, counted, and their distributions mapped. Eleven different sensillar types were found, including seven probable mechanoreceptors, two probable contact chemoreceptors, and two possible olfactory receptors. Other non-sensory aspects of the morphology of the legs and their roles in behaviour are described and discussed.
The metabolism of chlorinated aromatic pollutants by the frog
Authors: Safe S. , Jones D. , Kohli J. , Ruzo L. O. , Hutzinger O. , Sundstrom G.
Published: August 2008

The metabolism of several chlorinated aromatic pollutants has been studied using the frog species Rana pipiens as a model system. The substrates were administered by intraperitoneal injection and the metabolites were isolated and identified by chromatographic and spectroscopic methods. Chlorinated biphenyls, naphthalenes, and benzenes gave a range of hydroxylated products: 4-chlorobiphenyl was converted into 4′-chloro-4-biphenylol, 4′-chloro-3,4-bi-phenyldiol, and 4′-chloro-3-methoxy-4-biphenylol; 4,4′-dichlorobiphenyl gave 4,4′-dichloro-3-biphenylol and commercial Aroclor 1254 yielded mono-, di- and tri-chlorobiphenylols; 1-chloro- and 1,4-dichloro-naphthalene gave 4-chloro- and 2,4-dichloro-naphthol respectively; a series of lower chlorinated (monotetra) benzene isomers were also hydroxylated, whereas the pentachloro and hexachloro isomers did not yield any metabolic products. The results also suggested that biohydroxylation in the frog is similar to that of mammalian systems in which arene oxide intermediates are involved.
Actinlike filaments in the neurosecretory cells of Helisoma duryi (Gastropoda, Pulmonata)
Authors: Saleuddin A. S. M. , Jones Gwyneth M.
Published: August 2008

The mediodorsal neurosecretory cells in the cerebral ganglia of Helisoma duryi send axons into the median lip nerve, where they terminate to form a probable neurohaemal area. After glycerination these cells are shown to contain a branching network of 5- to 6-nm diameter filaments, which are abundant throughout the axon and axon ending but less prominent in the perikaryon. The filaments react with heavy meromyosin subfraction SI, increasing in thickness and forming arrowhead-shaped complexes; the reaction is reversed by adenosine 5′-triphosphate (ATP). This reaction indicates that the filaments contain actin, and it is suggested that actin–myosin interactions could be responsible for neurosecretory granule transport along the axon.
Seasonal changes in abundance of Gammarus oceanicus (Crustacea, Amphipoda) in Newfoundland
Authors: Steele D. H.
Published: August 2008

Abundance of Gammarus oceanicus reaches a peak in late summer – early autumn and declines to a low in the spring just before the young are produced. G. oceanicus disappears from the upper beach in late autumn, but is found permanently at lower levels. At low tide the numbers found under stones vary directly with stone size and inversely with the level of the stone on the beach. This, in turn, is related to environmental temperature. In the microhabitat under the stones, temperature varies inversely with stone size and directly with the level on the beach.
Congenital defects in the brood of a prairie rattlesnake
Authors: Pendlebury George B.
Published: August 2008

A prairie rattlesnake Crotalus v. viridis, kept in captivity during the last 2 months of gestation, produced nine infertile eggs, two eggs containing embryos, one dead young, and one live young. The embryos and young were all in different stages of development. Various congenital defects were apparent. While these defects may have been genetically controlled, it is speculated that they resulted from the fact that the gravid female did not have access to elevated temperatures during the late stages of gestation.
The blind aquatic isopod Salmasellus from a cave spring of the Rocky Mountains' eastern slopes, with comments on a Wisconsin refugium
Authors: Clifford Hugh F. , Bergstrom Glen
Published: August 2008

The blind hypogean asellid Salmasellus steganothrix Bowman (Crustacea: Isopoda) is reported from a cave spring located on the eastern slopes of the Rocky Mountains of Alberta, Canada. This is the only known aquatic isopod from Alberta and represents an extraordinary range extension for North American hypogean isopods. Water temperatures of the spring are almost constant, near 7 °C, for about 9 months of the year, but fluctuate because of snow melt in May, June, and July. Dissolved oxygen is often less than 1 mg/1 during the winter, and the isopod has not been collected from December through May, even though the spring is sampled at about monthly intervals. The distribution record is considered to be evidence supporting the existence of unglaciated low-elevation refugia on the eastern side of the Canadian Rocky Mountains during Wisconsin time.
Influence of photoperiod and temperature on developmental time and number of molts in nymphs of two species of Odonata
Authors: Ingram Byron R. , Jenner Charles E.
Published: August 2008

Nymphs of the damselflies Enallagma hageni and Enallagma aspersum were collected in North Carolina from August to March and subjected to 11- and 14-h photoperiods at 16 and 21 °C. Development was generally completed more rapidly under long-day conditions. Under all day-length and temperature regimes, developmental time from the middle instars to emergence decreased from a maximum for those nymphs collected in August to a minimum for those collected in March. The two species had similar developmental times under long photoperiods at 21 °C; short photoperiods, however, were more inhibitory to the growth of E. hageni than to E. aspersum. The photoperiodic responses of E. hageni were similar at both temperatures, the developmental times being only slightly slower at 16 °C. In contrast, nymphs of E. aspersum kept at 16 °C showed no photoperiodic response. In both species, diapause or prolonged development occurred primarily in the two instars before the final, but not in the final itself.Extra molts usually accompanied slow developmental times in both species, regardless of photoperiod. The incidence of extra molting was greatest under conditions combining high temperature and short daylength. Extra molts were apparently common in field populations of E. aspersum, but were rare in those of E. hageni.
Development of Camallanus adamsi Bashirullah, 1974 (Nematoda: Camallanidae) in cyclopoid copepods
Authors: Bashirullah A. K. M. , Ahmed Benazir
Published: August 2008

The larval development of Camallanus adamsi Bashirullah, 1974 was followed in intermediate hosts, Mesocyclops leuckarti (Claus) and Thermocyclops crassus (Fischer), which were kept at 24 °C and 27 °C (average). The nematode molted twice in the haemocoel of copepods. The first molt occurred 117 h after infection at 24 °C and the second molt after 249 h. At 27 °C, the first and the second molts occurred 72 and 168 h respectively after the infection. Three larval stages are described.
Porcellio spinicornis Say (Isopoda) demography. III. A comparison between field data and the results of a simulation model
Authors: McQueen Donald James
Published: August 2008

A simulation model for a Porcellio spinicornis Say population was constructed using laboratory data for rates of growth, reproduction, and survival and using winter survival rates observed in the field. The simulated output was compared with field data collected from 1971 to 1973. The expected and observed weight distributions and reproductive periodicities showed good agreement. The expected and observed patterns of numerical change also agreed for all life-history stages, except 18-month-old individuals, which disappeared from the field counts more quickly than expected. Sensitivity analysis showed that the time at which reproduction began each year was not as critical to population growth as were the effects of minor shifts in temperature on individual growth and survival rates. Furthermore, individual growth rate emerged as the factor having the greatest effect on patterns of population growth. Since the laboratory data on growth was reasonably accurate it is probable that the simulation model adequately describes the processes that determine the changes observed in the field population monitored during this study. All of the evidence indicated that during the period of study the population did not increase or decrease and that temperature conditions modifying demographic rates could have accounted for this observation.
Interpretation of Quaternary paleoecology from Cladocera and midges, and prognosis regarding usability of other organisms
Authors: Frey David G.
Published: August 2008

Sedimentary remains of chydorid Cladocera are abundant and can be identified precisely to species. Their percentage composition by species in sediments is integrated over habitats and seasons. Under stable conditions the relative frequency distribution of species corresponds to the MacArthur broken-stick model, so that marked departures from the predicted distributions indicate perturbations in the system. Lakes differ greatly in their capacity to buffer the effects of external changes. Cladocera can also indicate fluctuations in lake level, the changing effectiveness over time of size-selective predation, and broad patterns of climatic change through invasion and extinction of species. The remains of dipterous larvae (chiefly Chironomidae) are not only much less abundant than Cladocera but also have a much greater taxonomic uncertainty. Nevertheless, the profundal taxa provide clear insight into changing conditions in the hypolimnion over time and of the long-term readjustments and changes in the total fauna and their environmental correlates. Rhizopods, neorhabdocoeles, and rotifers, although barely studied to date, give promise in helping interpret past conditions.
Evidence of pregnancy failure in the wild meadow vole, Microtus pennsylvanicus
Authors: Mallory F. F. , Clulow F. V.
Published: August 2008

Normal and blocked pregnancy were studied in the meadow vole, Microtus pennsylvanicus (Ord), in the laboratory, on individuals bred from wild stock caught near Sudbury, Ontario. The results were then compared with those obtained from wild voles trapped from quadrats during the summers of 1969 and 1970.Criteria were found for distinguishing between individuals in which pregnancy had been blocked and those in which it had not, under laboratory conditions. Nursing females were not found to be susceptible to male-induced blockage and the second set of corpora lutea in the ovaries was not observed to increase the rate of involution of the first set. Females were found to be susceptible to blockage on the 2nd and 5th days after coitus.Some indication of pregnancy failure in the wild was found and the incidence of this phenomonon appears to increase in populations with a higher density. Thus it seems reasonable to hypothesize that pregnancy failure is one of the density-dependent factors that decreases reproduction and ultimately the recruitment of young animals to the population.
Age determination of harbour porpoise, Phocoena phocoena (L.), in the western North Atlantic
Authors: Gaskin D. E. , Blair B. A.
Published: August 2008

Age, based on analysis of dentinal growth layers, was determined in a sample of 121 harbour porpoises, Phocoena phocoena (L.), from western North Atlantic waters. One growth layer, consisting of a thick opaque zone and a relatively thin translucent zone, is deposited each year.Mean thicknesses of opaque and translucent zones in males and females were 347 μm, 114 μm, 432 μm, and 125 μm, respectively. Significant reduction in thicknesses of growth layers with age was found in both sexes, the major contribution in both cases being progressive reduction in thickness of the opaque zones. Translucent-zone thickness decreased with age in males, but significantly increased in thickness in females. Formation of the opaque zone occurs from June through February, and formation of the translucent zone from January to early September. This overlap is attributed to the protracted calving season of this population, and precludes any simple relationship between food supply and zonation, as proposed by others. Age–length relationships based on numbers of dentinal layers were calculated for males and females using regression analysis. Best fits of body length (b) against age (expressed by completed dentinal layers) (d) were obtained from the curvilinear equations: d = [b/(−1.30b + 209.35)] −1 for males, and d = [b/(−0.84b + 156.15)] −1 for females.
Diplostomum adamsi sp.n.: description, life cycle, and pathogenesis in the retina of Perca flavescens
Authors: Lester R. J. G. , Huizinga H. W.
Published: August 2008

Forty-two perch eyes (Perca flavescens) infected with metacercariae of Diplostomum adamsi were fed to a herring gull (Larus argentatus). Eighty adults were recovered from the intestine 10 days later. They were characterized by their small size (1.5 to 2.1 mm), asymmetrical anterior testis, and the absence of vitellaria in forebody anterior to the middle of the ventral sucker.Eggs of D. adamsi passed by the gull embryonated in 22 days at 22 °C and hatched when exposed to light. Miracidia penetrated snails of the species Lymnaea elodes and L. stagnalis. Forty days later straight-tailed cercariae with six pairs of caudal bodies were released from both lymnaeids. They penetrated and developed in P. flavescens but not in Salvelinus namaycush, Catostomus commersoni, Semotilus atromaculatus, or Carassius auratus. In P. flavescens, metacercariae were found in clusters in the peripheral retina, in a cavity between the photoreceptor cells and the pigment epithelium. The photoreceptor cells were disorganized but not destroyed, unlike those in the eyes of Gasterosteus aculeatus parasitized by D. scudderi.
The spring decline in deer mice: death or dispersal?
Authors: Fairbairn Daphne J.
Published: August 2008

Demographic processes associated with the onset of breeding in spring are examined in a population of deer mice, Peromyscus maniculatus. Many mice of both sexes disappear from the population at this time. The disappearance of males appears to result from the dispersal of light-weight, subordinate animals. The disappearance of females, however, appears to be due mainly to mortality of early-breeding females. The consequences of this difference between the sexes for limitation of breeding densities are discussed. Two hypotheses relating the population processes of males to those of females are presented, and a possible experimental test of these is described.
The effect of photoperiod on diapause induction, and temperature on diapause termination in embryos of Aedes campestris Dyar and Knab (Diptera: Culicidae)
Authors: Tauthong P. , Brust R. A.
Published: August 2008

Populations of Aedes campestris from Manitoba and Saskatchewan were found to be either multivoltine or univoltine depending upon the geographical region from which the adults were collected. Three southern populations (from 49–52° N) were found to be totally multivoltine, whereas a northern population (58° N) was found to be partially (36%) univoltine. The latter fraction was designated as univoltine because the eggs entered an obligatory diapause after oviposition. When univoltine eggs were placed at 30 °C for a period of 10 days, 59% of the eggs hatched when subjected to a hatching stimulus.Facultative dispause was induced in eggs of multivoltine populations of A. campestris, by subjecting fully embryonated eggs to photoperiods of less than 14 h per day. For example, after 30 days at 8 h light: 16 h dark 73% of the eggs entered diapause.
Pachyporospora retorta Ormières pacifica ssp.nov. (Eugregarina, Porosporidae), parasite de Cancer productus Randall (Brachyura, Cancridae) à Nanaimo, Colombie-Britannique. Remarques sur le cycle des Pachyporospora Théod., 1961
Authors: Théodoridès Jean
Published: August 2008

A description of Pachyporospora retorta Ormières pacifica ssp.nov., an intestinal parasite of the crab Cancer productus Rand. from Nanaimo, British Columbia, is given, and the life cycle of the Gregarines belonging to the genus Pachyporospora Théodoridès is considered.
An estimate of the mortality in a population of Perca flavescens owing to the trematode Diplostomum adamsi
Authors: Lester R. J. G.
Published: August 2008

A truncated form of the negative binomial distribution was fitted to the frequency distribution of 5117 metacercariae of Diplostomum adamsi in 115 Perca flavescens taken from the Bay of Quinte, Lake Ontario. Comparison between the fitted curve and the actual distribution suggested that 78 heavily infected fish were missing from the sample. Field and laboratory data indicated that this was due to a higher mortality in the heavily infected fish, particularly during their first 2 years of life, rather than to inadequate sampling, host resistance, or parasite–parasite interaction.
The description of a gubernaculum in Ascarops strongylina (Rudolphi, 1819) (Spiruroidea) and a note on the recovery of this nematode from a bird
Authors: Webster W. A. , Speckmann G.
Published: August 2008

A gubernaculum is demonstrated in the male Ascarops strongylina (Rudolphi, 1819) by examination of serial sections of the caudal region. Mature specimens of A. strongylina were found in a bird, a greater sulphur-crested cockatoo, Cacatua galerita.
The dynamics of collembolan populations: a matrix model of single species population growth
Authors: Longstaff Barry C.
Published: August 2008

The construction of a matrix model for the growth of populations of soil Collembola is described. Data from four replicate cultures of each of two species kept under laboratory conditions were modelled in the form of difference equations, which took into account the size structure of the populations. These equations were set up so as to effect a Leslie-type matrix model. The effect of density upon population growth rate was incorporated into the model in the form of a density-related function for fecundity.The success of the modelling procedures was varied with some of the models accurately predicting both the pattern of population growth and the population sizes at successive time intervals, whilst others only showed the trends. The deterministic models of each of the replicates for each species were combined to produce a stochastic model for that species. These also met with mixed success. The equilibrium values for the deterministic models were calculated and their stability properties examined. The models for both species predict a stable equilibrium approached by a series of damped oscillations.
Fine-structural cytodifferentiation in thyroid glands, adrenal glands, and testes from an exceptionally old partially decapitated, hypophyseoprivic chicken embryo
Authors: Betz T. W. , Narbaitz R.
Published: August 2008

Fine structure of thyroid glands, adrenal glands, and testes from a rare, 25.5-day-old chicken embryo (with patent esophageal entrance), which was made hypophyseoprivic by partial decapitation, was studied to establish if these gland cells could differentiate in the prolonged absence of the hypophysis and other possible factors. Endocrine cells in these glands had all cytoplasmic characteristics usually seen in fully differentiated gland cells but only the thyroid and adrenal gland cells were less developed. These results show that without the hypophysis or other factors from the missing head parts of partial decapitates (such as the epiphysis and hypothalamus) cytodifferentiation can be completed. Also, differentiation was not prevented by theoretically reduced amounts of albumen ingested by the operated embryo.
Laboratory culture of the free-living stages of Neomesomermis flumenalis, a mermithid nematode parasite of Newfoundland blackflies (Diptera: Simuliidae)
Authors: Bailey C. H. , Gordon R. , Mills C.
Published: August 2008

Laboratory methods were developed for culturing the free-living stages of Neomesomermis flumenalis from field-collected blackfly larvae. The best results were obtained by placing 50 pairs of nematodes under xenic conditions in 500-ml containers containing about 450 ml of wet sand. With this method, 78.6% of the females introduced to culture reproduced. The influence of factors such as microorganisms, substrate, container volume, and sterility on culturing these mermithids is discussed. Differences were noted in the development of N. flumenalis from winter-breeding Prosimulium hosts and those from summer-breeding Simulium hosts. Parasites from Simulium developed nearly twice as fast as from Prosimulium hosts at 10 °C. Temperature studies showed that Simulium parasites were better adapted for higher temperature ranges (20 °C) but were more poorly adapted to lower temperatures (5 °C) than parasites from Prosimulium. The noted differences suggest two physiological strains of the same species, one developing in Simulium spp., the other in Prosimulium spp.
Demography of a subarctic population of Clethrionomys gapperi: size and growth
Authors: Fuller W. A.
Published: August 2008

Neither mean weight nor mean length of samples of Clethrionomys gapperi trapped in May was correlated with population size, spring weather, or mean age of the animals. Winter-caught samples showed no growth in length between September and April, but rapid growth from April to May. The ratio of May length to length the previous fall, used as an index of growth, was strongly correlated with mean maximum temperature for the period 16 April to 15 May (r = 0.89 for males, 0.97 for females). Weight declined from September to April, then increased rapidly from April to May. The ratio of May weight to weight the previous fall was correlated with spring temperature in 4 years out of 5. The exception was the peak spring of 1974, when increase in weight was greater than expected in view of the low temperature. This suggests that the animals in the peak spring were qualitatively different from those in other years, but that the difference was expressed as rapid growth rather than as large size per se. It is suggested that spring growth may be a more useful indicator of changes in the quality of individuals in fluctuating microtine populations than absolute size in spring.
The fine structure of sporogony in Myxidium zealandicum (Protozoa: Myxosporidia)
Authors: Hulbert W. C. , Komourdjian M. P. , Moon T. W. , Fenwick J. C.
Published: August 2008

Studies of the ultrastructure of the trophozoite (plasmodium) and the process of sporogony and polar capsule development of Myxidium zealandicum from gill and kidney of the North American eel Anguilla rostrata are described. Although the basic steps and characteristics of sporogony are similar to those previously reported for other myxosporidians, we report three new and significant observations in this study: (1) the identification of a uninucleate germ cell for the binucleate sporocyst; (2) the asynchronous maturation of polar capsules within a single sporocyst; and (3) the existence of a mitochondrial layer at the periphery of the Plasmodium that may have a transport function. We also observed cylindrical and spherical structures, either of which might be the primordium of the polar capsule, but we were unable to resolve this problem. These observations are discussed with reference to previous descriptions of myxosporidians.
Pituitary control of pigmentation in xanthic, moor, and white Carassius auratus L
Authors: Leatherland J. F. , Bekolay R. , McLean R. S. , Brown D.
Published: August 2008

After hypophy sectomy some of the melanophores in moor fantail goldfish (Carassius auratus L.) underwent lysis and the remaining cells showed melanin aggregation. The orange colour in xanthic. moor, and white fantail varieties of goldfish 'pales' after hypophysectomy. Homogenates of whole pituitary, pars distalis, or neurointermediate lobe tissue given as intraperitoneal injections effected a marked increase in the melanophore index in hypophysectomized moor fantails and intensified the orange colour in hypophy sectomized moor and xanthic fantails.Ovine prolactin, ovine thyrotrophs (TSH), ovine somatotrophs (STH), and a combination of ovine luteinizing hormone (LH) and porcine follicle-stimulating hormone (FSH) were effective in increasing the melanophore index in hypophy sectomized moor fantails. Of these four preparations the LH–FSH combination was the most potent. Saline and thyroxine were without effect.Ovine prolactin, ovine STH. and a combination of ovine LH and porcine FSH restored the orange colour of hypophysectomized xanthic and moor fantails. Of these three preparations the LH–FSH was most potent. Saline, ovine TSH. and thyroxine were without effect.Differences were found in the apparent activity of prolactin, thyrotroph, gonadotroph, and putative melanocyte-stimulaling hormone (MSH) cells in the pituitaries of the three varieties of goldfish but these could not be directly correlated with pigmentation differences between the groups.
Fossil caddisflies (Insecta: Trichoptera) from the Don Formation, Toronto, Ontario, and their use in paleoecology
Authors: Williams Nancy E. , Morgan Alan V.
Published: August 2008

Chitinous parts of caddisfly larvae have been recovered from Sangamonian Interglacial silts and clays from the Don Valley brickyard Toronto, Ontario. These indicate that deposition took place at the mouth of a river. Various characteristics of this river, the large lake into which it flowed, and the watershed are deduced. It is suggested that the prognosis for paleoecological use of this insect group is good.
Aspects of the comparative behavior of red-eyed and Philadelphia vireos
Authors: Barlow Jon C. , Rice James C.
Published: August 2008

Specific postural and vocal displays in successive stages of the nesting cycle are compared between sympatric red-eyed and Philadelphia vireos based on 9 years of field studies in Ontario and elsewhere. Vireos reach northern Ontario between mid-May and early June. Territorial behavior, including crest-erect alert, head forward threat, tail-fanning, and gaping, are seen in both species but at different frequencies. Physical encounters include supplanting, circle chasing, pecking, and grappling. Epigamic behavior begins immediately in both with pair formation, which differs only in timing between the two species. Pairs are maintained by male and female wing-quiver, female squat, and male swaying displays. Swaying in red-eyed vireos involves feather erection, tail-fanning, and continuous asynchronous swaying of the body, head, and neck. Swaying is simpler in Philadelphia vireos. Intrapair aggression, displacement preening, and interruptions of courting birds by third adults are discussed. Special vocalizations: 'myaah' and warbling song (red-eyes) and 'ehhh,' 'bubble' song, and contact notes (Philadelphias) are discussed. Nest site selection and nest building are done only by females in both species. Philadelphia vireo males incubate; red-eyed vireo males do not. Males of both species feed nestlings and fledglings. Evolutionary implications of the display and behavioral patterns of the two species are discussed.