bluuebunny/crossref_metadata_2025 huggingface dataset:
Intestinal helminths of lesser scaup ducks: patterns of association
Authors: Bush Albert O. , Holmes John C.
Published: August 2008

The helminth communities of the small intestines of 45 lesser scaup ducks sampled from 13 lakes in Alberta, Canada, were examined for patterns of association among species. A core of eight frequent, numerous, and positively associated species provided a basic similarity across all host individuals. Six of these core species are specialists in lesser scaup, and the other two are generalists in waterfowl. A group of eight moderately frequent and numerous species, which were positively associated with the core species but not with each other, also contributed to this similarity; these secondary species included two specialists in scaup and three generalists in waterfowl. The 36 remaining "satellite species" appeared to be distributed randomly among birds. Variations among communities in individual birds were due largely to (i) differences in the numbers of two suites of helminth species, one using Hyalella azteca and the other Gammarus lacustris as intermediate host; (ii) differences in the numbers of the Hyalella suite, and in the presence or absence of some secondary or satellite species, associated with the lake from which the duck was taken; and (iii) differences in the total numbers of helminths per duck, which may be associated with differential susceptibility of individual ducks.
Winter behavior of moose in central Sweden
Authors: Sweanor Patricia Y. , Sandegren Finn
Published: August 2008

We studied the social behavior of moose (Alces alces alces) in central Sweden during late winter in 1983 and 1984. We observed 119 groups during 797 pair-hours. Moose formed temporary groups [Formula: see text] where individual distances were 50 m or less. Most feeding and resting activities in multimembered groups were synchronized. Grouped moose interacted agonistically at a mean rate of 0.18 interactions per pair-hour. Group associations and interaction rates were dependent on the sex class of moose involved. A concentrated food site of naturally occurring browse did not increase interaction rates or group sizes. No one sex class won interactions at a higher rate than any other. Common threatening actions of moose were lowering the head, positioning the ears downward, and looking directly at and moving towards an opponent. Common losing responses were positioning the ears backward, lowering the head, looking away, and stepping away from an instigator.
Biochemical characterization of some raptor trypanosomes. I. In vitro cultivation and lectin-binding studies
Authors: Kirkpatrick Carl E. , Terway-Thompson Cynthia A.
Published: August 2008

Nine trypanosome strains from five species of raptors were cultivated in vitro in a monophasic medium. Two morphologically distinct trypanosomes were observed in culture: those from American kestrels (Falco sparverius) were smaller than the other strains. The two kestrel (KT) trypanosome strains showed in vitro growth kinetics that differed from the larger trypanosomes, and the KT strains, unlike the others, required hemin in the medium for growth. The effectiveness of eight plant lectins to induce the agglutination of cultured trypanosomes was studied as a means of differentiating the various strains. It was found that lectins from Lens culinaris and Ricinus communis (type I) were particularly effective in distinguishing the KT strains from the other raptor trypanosome strains. Based on the results of experiments in which lectin-mediated trypanosome agglutination was inhibited by the addition of various monosaccharides, it is concluded that all of the avian trypanosomes studied express surface methyl α-D-mannoside, D(+)-galactose, and (or) α-lactose. Only the relatively large raptor trypanosome isolates expressed N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and α-L(−)-fucose on their surfaces. The differences in lectin-binding characteristics between the two morphologic types of raptor trypanosome were as great as those among each of the avian trypanosomes and the mammalian trypanosomatids Leishmania chagasi and Trypanosoma rhodesiense.
Liver retinoid concentrations in natural populations of herring gulls (Larus argentatus) contaminated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and in ring doves (Streptopelia risoria) injected with a dioxin analogue
Authors: Spear Philip A. , Moon Thomas W. , Peakall David B.
Published: August 2008

Liver vitamin A was analysed by reverse phase high pressure liquid chromatography in a limited number of herring gull samples collected from New Brunswick coastal and Great Lakes colonies. Both retinol and retinyl palmitate concentrations were significantly different between the New Brunswick and Great Lakes colonies as well as among the Great Lakes colonies. The highest mean values were 864 and 1737 μg/g retinol and retinyl palmitate, respectively, occurring in the New Brunswick gulls. The lowest mean values were 131 and 231 μg/g retinol and retinyl palmitate, respectively, which were detected in Lake Ontario gulls. Retinoid levels were inversely related to the extent of dioxin contamination reported previously. Ring doves received single low-level doses of the dioxin analogue 3,4,3′,4′-tetrachlorobiphenyl and were sacrificed at various times postinjection. Liver retinol decreased significantly as aryl hydrocarbon hydroxylase activity increased. The decrease in retinol concentration was not related to UDP-glucuronyltransferase activity. Retinyl palmitate was unaffected by the analogue under the conditions of this study. These results support the hypothesis that, in wildlife species, hepatic retinoid metabolism is affected by chlorinated dibenzodioxins or other contaminants capable of inducing aryl hydrocarbon hydroxylase.
Vascular phase of Sarcocystis cruzi cultured in vitro
Authors: Speer C. A. , Dubey J. P.
Published: August 2008

Sporozoites of Sarcocystis cruzi penetrated various established cell lines but developed to meronts in bovine monocytes (BM) and bovine pulmonary artery endothelial cells (CPA) only. At 31 to 50 days after sporozoite inoculation, approximately four times more merozoites were harvested from cultures of CPA (72.7 × 106 merozoites) than from BM (16.6 × 106 merozoites). The ability to grow merogonous stages in vitro can now be used to elucidate pathogenetic and immunologic mechanisms associated with infection by Sarcocystis spp.
Effect of Orthene® on an unconfined population of the meadow vole (Microtus pennsylvanicus)
Authors: Jett David A. , Nichols James D. , Hines James E.
Published: August 2008

The possible impact on Microtus pennsylvanicus of ground applications of Orthene® insecticide was investigated in old-field habitats in northern Maryland during 1982 and 1983. The treatment grids in 1982 and 1983 were sprayed at 0.62 and 0.82 kg active ingredient/ha, respectively. A capture–recapture design robust to unequal capture probabilities was utilized to estimate population size, survival, and recruitment. Data on reproductive activity and relative weight change were also collected to investigate the effect of the insecticide treatment. There were no significant differences in population size or recruitment between control and treatment grids which could be directly related to the treatment. Survival rate was significantly lower on the treatment grid than on the control grid after spraying in 1983; however, survival rate was higher on the treatment grid after spraying in 1982. Significantly fewer pregnant adults were found on the treatment grid after spraying in 1982, whereas the proportions of voles lactating or with perforate vaginas or open pubic symphyses were slightly higher or remained unchanged during this period. Relative weight change was not affected by the treatment. Results do not indicate any pattern of inhibitory effects from the insecticide treatment. Field application of Orthene® did not have an adverse effect on this Microtus population.
Successful release of rehabilitated Merlins (Falco columbarius)
Authors: Warkentin Ian G.
Published: August 2008

Survival rates of released rehabilitated birds are rarely known. This paper describes the winter release of two Merlins (Falco columbarius), treated for ulnar fractures, in Saskatoon, Sask. Telemetry was used to maintain contact with one of these birds during the postrelease period, while the progress of the second was monitored through yearly nest surveys. Successful release is defined for Merlins as survival for at least 4 weeks. The first bird survived for 51 days, while the second lived at least 2 years and produced 10 young.
Effects of trematode parasitism on reproductive output of the bivalve Transennella tantilla
Authors: Kabat Alan R.
Published: August 2008

Transennella tantilla, a small protandric brooding marine bivalve (Veneridae), from San Juan Island, Washington, U.S.A., was studied to determine the effects of parasitic castration on reproductive output. In the population studied, 31% of the brooding females were infected with larvae of the digenetic trematode Telolecithus pugetensis. Usually, such parasites cause host sterility, but here a significant number of parasitized adults continued to produce and brood embryos, although at a lower rate than did nonparasitized adults. Sequential brooding in T. tantilla may allow parasitized females to continue producing small numbers of embryos. Parasitism plays an important role in limiting the total reproductive output of this population of T. tantilla.
Metabolic rates of seals and whales
Authors: Lavigne D. M. , Innes S. , Worthy G. A. J. , Kovacs K. M. , Schmitz O. J. , Hickie J. P.
Published: August 2008

A critical review of metabolic rate determinations for pinnipeds (seals, sea lions, fur seals, and walrus) and cetaceans (whales, dolphins, and porpoises) does not support the widely accepted generalization that they have higher metabolic rates than terrestrial mammals of similar size. This finding necessitates a rethinking of the thermoregulatory adaptations of these marine mammals for an aquatic existence and has important implications in comparative studies of mammals, which frequently omit marine forms because they are perceived to be "different" from other mammals. It also suggests that numerous studies have overestimated food consumption by marine mammal populations.
Phenology of the mosquito Wyeomyia smithii (Coq.) in Manitoba and Ontario
Authors: Farkas Martha J. , Brust Reinhart A.
Published: August 2008

The phenology of Wyeomyia smithii (Coquillett) within the water-filled leaves of Sarracenia purpurea L. (the purple pitcher plant) was studied during 1983 in bogs near The Pas and Patricia Beach, Manitoba, and Kenora, Ontario. Larvae that overwintered developed into adults by early July, and females laid eggs in newly opened leaves, as well as in the previous year's leaves. The largest portion of the developing larvae (summer generation) entered a third-instar diapause by mid-August and remained in this instar until the following spring. A small percentage of the summer generation at each site continued their development to adults and may have given rise to another generation. The number of larvae per leaf was positively correlated with leaf size. Pupation rates as well as adult size and fecundity did not vary significantly amongst sites. Smaller and less fecund individuals emerged as the season progressed. Over-winter survival of larvae was low at Patricia Beach (9%) but relatively high at The Pas (68%) during the winter of 1983–1984; survival was moderate (32–50%) during 1984–1985 at both locations. Overwintering success is likely enhanced by an early winter snow cover which insulates the larvae from low ambient temperatures from October to December at these sites.
Effect of hormone treatments on alarm substance cell counts in the pearl dace, Semotilus margarita
Authors: Smith Jeaniene D. , Smith R. J. F.
Published: August 2008

The seasonal loss of alarm substance cells that normally occurs in breeding male and female pearl dace, Semotilus margarita, could not be induced by treatment with androgen, estrogen, salmon gonadotropin, or prolactin. Treatment with carp pituitary did lead to a significant reduction in alarm substance cell numbers. Androgen treatment induced changes in tuberculation and mucous cell counts. Salmon gonadotropin and carp pituitary increased breeding colouration. Prolactin treatment increased mucous cell counts. The lack of response of pearl dace alarm substance cells to androgen contrasts with the situation in fathead minnows, Pimephales promelas, where seasonal alarm substance cell loss is under androgen control. The difference may reflect differences in the annual cycle of secondary sexual characteristics.
Seasonal energy expenditures and thermoregulatory responses of moose
Authors: Renecker Lyle A. , Hudson Robert J.
Published: August 2008

Metabolic rates and thermoregulatory responses were studied in adult moose (Alces alces) exposed to various ambient temperatures during winter and summer. Resting energy expenditures followed a marked annual cycle with a maximum (940 kJ kg body weight−0.75 d−1) during spring – early summer and minimum (430 kJ kg body weight−0.75 d−1) during winter. The heat increment of feeding associated with a pelleted ration was 6–9 kJ kg body weight−0.75 h−1. The energy cost of standing was 4.2 kJ kg body weight−0.75 h−1, an increment of 25% over the lying posture. Although piloerection was observed between −25 and −30 °C, metabolic rates did not increase. In contrast to their cold tolerance, moose were easily heat stressed. During winter, moose increased respiration rates when ambient temperatures rose above −5 °C. Resistance to heat load was greater for standing moose during summer; respiration rate increased above 14 °C and open-mouthed panting began at 20 °C. Energy expenditure and heart rate followed a similar rise with increasing ambient temperature.
Developmental allometry in three species of darters (Percidae: Etheostoma)
Authors: Paine Michael D.
Published: August 2008

Ontogenetic changes in body form of three Etheostoma species were compared among species within life history periods and among periods within species. Slopes of allometric equations were similar across species, but differed among periods. The overall similarity of early ontogenetic changes, including shifts at period thresholds, suggested common, perhaps ancestral, developmental restrictions. Differences in elevations of allometric equations among species within periods may be more relevant ecologically. Interspecific differences among adults were not evident among juveniles; the three species were very similar as juveniles. Divergence of adult allometric coefficients, anisometry in adults, and the presence of sexual dimorphism all indicated that considerable differentiation may take place after fish reach 20 mm total length.
Two new species of eriophyid mites (Prostigmata: Eriophyidae) on wild geranium (Geranium carolinianum L.) in Mississippi
Authors: Chandrapatya A. , Baker G. T.
Published: August 2008

The adult and immature stages of two new species of mites, Coptophylla caroliniani and Aceria mississippiensis, found on Geranium carolinianum L. in Mississippi, are described. Both species are found on the upper and lower surfaces of leaves and cause deformations to the plant. Coptophylla caroliniani induces erinea and A. mississippiensis causes leaf and shoot deformation.
The life history, nymphal growth rates, and feeding habits of Siphlonisca aerodromia Needham (Ephemeroptera: Siphlonuridae) in Maine
Authors: Gibbs K. Elizabeth , Mingo Terry M.
Published: August 2008

Siphlonisca aerodromia Needham has a univoltine life history in Maine. Adults emerge in late May or early June. Each female contains about 394 large (0.46 mm long) eggs covered with coiled fibers that anchor the eggs to the substrate. Eggs are deposited in the main channel of the stream and small nymphs appear in January. Nymphal growth rate (GHW) was expressed as a percent per day increase in head width. Initially nymphs feed on detritus and grow slowly (GHW = 0.28–0.79) at water temperatures near 0 °C. Following snow melt, the nymphs move into the adjacent Carex floodplain. Here, water temperature increases, animal material, in the form of mayfly nymphs, becomes increasingly common in the diet, and growth rate increases (GHW = 2.13–2.89). The sex ratio of nymphs collected in May and June was 1:1.8 (male:female).
Gross anatomy and fine structure of the gut of the marine mysid shrimp Mysis stenolepis Smith
Authors: Friesen J. A. , Mann K. H. , Willison J. H. M.
Published: August 2008

The structure of the digestive tract of Mysis stenolepis was studied by light and electron microscopy. The cardiac portion of the stomach is armed with dorsal, lateral, and ventral chitinous ridges. The pyloric stomach is divided by ridges and stiff hairs into an upper chamber through which most of the food passes and a lower chamber containing only fluid and fine particles. The hepatopancreas consists of five paired lobes that open into the junction of the stomach and midgut in such a way that only the fluid and fine particles from the ventral chamber of the stomach enter its tubules. Other material passes from the dorsal chamber to the midgut and is eventually voided. The fine structure of the hepatopancreas and other parts of the gut are described.
Mysis digests cellulose in the absence of a gut microflora
Authors: Friesen J. A. , Mann K. H. , Novitsky J. A.
Published: August 2008

Light and electron microscope investigations of the gut of the mysid shrimp Mysis stenolepis, previously shown to be capable of digesting cellulose, revealed no evidence of a gut microflora. The densities of bacteria in the guts of freshly collected mysids were of the same order of magnitude as on the eelgrass detritus on which they feed. Preliminary experiments with mysid gut extracts indicate a significant ability to convert cellulose to soluble sugars by means of endogenous cellulases.
Differential centrifugation, calcium precipitation, and ultrasonic disruption of midgut cells of Erinnyis ello caterpillars. Purification of cell microvilli and inferences concerning secretory mechanisms
Authors: Santos Custódio D. , Ribeiro Alberto F. , Terra Walter R.
Published: August 2008

Subcellular fractions of the cells from the first and last third of midguts from Erinnyis ello caterpillars were obtained by conventional homogenization, followed by differential centrifugation or differential calcium precipitation, as well as by partial ultrasonic disruption. Aminopeptidase was enriched in the subcellular fractions, which in the electron microscope display mainly microvilli from the columnar cells (obtained by differential centrifugation and ultrasonic disruption), and also in the microvilli fraction obtained by differential precipitation. To account for the enzyme activities that sedimented with vesicles displaying brush borders, major amounts of the soluble glycosidases (cellobiase, N-acetylglucosaminidase, maltase, and trehalase) are assumed to be loosely bound to the cell glycocalyx, from where they are set free by homogenization and (or) freezing–thawing. Intracellular glycosidases seem to be bounded by membranes, which sediment together with vesicles that resemble secretory vesicles. The soluble form of amylase occurred mainly associated with the microvilli of anterior midgut cells and is supposed to be contained inside small vesicles, which are seen budding along columnar cell microvilli and fusing one with the other and with the tips of the microvilli from the anterior midgut cells. Secretory mechanisms are discussed in the light of the evidence that the posterior midgut secretes whereas the anterior midgut absorbs water.
Helminths of pink salmon, Oncorhynchus gorbuscha, from five tributaries of Lake Superior and Lake Huron
Authors: Muzzall Patrick M. , Peebles C. Robert
Published: August 2008

Adult salmon (93 pink salmon, Oncorhynchus gorbuscha; 8 coho salmon, O. kisutch; and 5 chinook salmon, O. tshawytscha) were collected from four tributaries of Lake Superior and one of Lake Huron in September–October 1983 and 1984, and examined for helminths. Fourteen species (1 Digenea, 4 Cestoda, 6 Nematoda, 3 Acanthocephala) were found in the digestive tract and other viscera. Nine, 6, and 7 new host records are reported for pink, coho, and chinook salmon, respectively. Cystidicola farionis and Echinorhynchus salmonis were the most common and numerous helminths in each salmon species. Fifty pink salmon fry and 35 chinook salmon fry collected in May 1984 were negative for parasites.
Reduced alarm substance cell counts in male and androgen-treated zebra danios (Brachydanio rerio)
Authors: Smith R. J. F.
Published: August 2008

Ostariophysan fish possess large epidermal cells that contain the alarm substance or Schreckstoff characteristic of this group. In some species these alarm substance cells are retained throughout the reproductive cycle; in others they are completely absent from the epidermis during the breeding season in males only or in both sexes. Zebra danios represent a fourth category: males have fewer alarm-substance cells than do females and treatment with 17α-methyltestosterone leads to a further reduction, but not complete absence, of alarm substance cells. Treating females with 17α-methyltestosterone reduced the number of alarm substance cells in their epidermis.
Production energetics of a population of sockeye salmon, Oncorhynchus nerka
Authors: Brett J. R.
Published: August 2008

The life stages and population structure of sockeye salmon from Babine Lake, British Columbia, are outlined. The total biomass produced by an average cohort of smolts is determined by tracing the monthly growth and mortality rates for each of three age-classes during ocean life, based on models responsive to life history, temperature, and body weight. From an energy budget previously deduced for an average 4-year-old sockeye salmon, the growth efficiency of the cohort is derived (22.8%). Assumptions and possible sources of error are discussed, concluding with comments on the high energy conversion efficiency of an average sockeye salmon population during marine life.
Effect of conspecifics on winter movements and dispersion in an overwintering bank vole (Clethrionomys glareolus) population
Authors: Karlsson A. Fredric
Published: August 2008

Patterns of movements and dispersion were studied in a population of the bank vole, Clethrionomys glareolus, during two winters near Uppsala, Sweden. Forty-one percent of the individuals studied were involved in multiple captures. However, multiple captures accounted for only 2% of all captures. Males and females were most often caught together in multiple captures. An overlap in home range was more pronounced in females than in males during winter. The reverse was observed during the reproductive season. An increase in mean distance, calculated for neighbours within 40 m of the center of activity, was observed among persistent females from October to May. Statistically significant differences were obtained when mean distances were compared between females still present in the trapping area in May who then produced young and females trapped up to April but not thereafter. Thus, early access to optimally spaced, high quality home ranges may be important for reproductive success in spring. Extensive overlapping of female home ranges in winter at low population density may be a consequence of habitat conditions.
Proximate causes of losses in a snowshoe hare population
Authors: Boutin Stan , Krebs C. J. , Sinclair A. R. E. , Smith J. N. M.
Published: August 2008

We used radiotelemetry to monitor proximate causes of mortality of snowshoe hares during a population increase, peak, and decline at Kluane Lake, Yukon. Predation and starvation rates increased 1.6- and 9-fold, respectively, in the winter of peak population density. Predation accounted for 58% of the losses during the winter of peak densities while losses were equally divided between predation and starvation in the winter following the peak. Starvation and predation rates were lower on a food-supplemented grid than on control grids in the peak winter. In the following spring and winter, starvation rates remained low on the food grid while predation rates increased to equal those on control areas. We conclude that both starvation and predation were the proximate causes of mortality during the hare decline at Kluane Lake.
The influence of insects on the distribution, microhabitat choice, and behaviour of the Burwash caribou herd
Authors: Downes C. M. , Theberge J. B. , Smith S. M.
Published: August 2008

This study examined the influence of insects (mosquitoes and oestrids) on the distribution, microhabitat choice, and behavior of a population of mountain caribou. The study was conducted in the Burwash area of southwestern Yukon Territory during the summers of 1982 and 1983. Mosquito density, the presence or absence of oestrids, and the distribution, microhabitat use, and insect-avoidance behavior of the caribou were observed. Seasonal activity budgets for caribou were calculated. Mosquitoes became active in mid-June. Activity decreased with altitude, and at the highest altitudes (2000 m) the number of mosquitoes was negligible. Snow patches and exposed windy ridges had fewer mosquitoes than did open tundra. The oestrid season began in late June and lasted until early August. Oestrids were widespread throughout the study area and were present in all microhabitats. Caribou reduced harassment by mosquitoes by their altitudinal movements and use of microhabitat. Oestrids influenced activity budgets of caribou, acting to decrease feeding and resting time and to increase the time spent standing and moving.
On Gyrodactylus katharineri Malmberg, 1964, G. lotae Gussev, 1953, and G. lucii Kulakovskaya, 1952 from host fishes in North America
Authors: Cone D. K. , Dechtiar A. O.
Published: August 2008

Gyrodactylus katharineri Malmberg, 1964, G. lotae Gussev, 1953, and G. lucii Kulakovskaya, 1952 are reported for the first time from North American host fishes (Cyprinus carpio, Lota lota, and Esox lucius, respectively). The new material is described. Gyrodactylus katharineri is an introduced species that apparently arrived along with host shipments brought to North America from Europe during the last century. Gyrodactylus mizellei Kritsky and Leiby, 1971 may be a synonym of G. katharineri. Gyrodactylus lotae and G. lucii are endemic species with natural ranges that extend throughout freshwaters of Eurasia and North America.
Life cycles, reproduction, and diets of Dina dubia and Erpobdella punctata (Hirudinea: Eropobdellidae) in Canagagigue Creek, Ontario
Authors: Barton David R. , Metcalfe Janice L.
Published: August 2008

The life cycles of Dina dubia and Erpobdella punctata were described from semimonthly (monthly in winter) collections made at two sites on Canagagigue Creek between May 1982 and July 1983. Observations on reproduction were made in the creek and in a flow-through stream tank. Most individuals of both species completed their life cycles in about 1 year, but some required 2 or more years to reach sexual maturity. The estimated average fecundity (138–173 young/adult), growth rate, and maximum size (1946 mg live weight) of E. punctata were all greater than for D. dubia (47–50 young/adult; maximum size, 725 mg), but D. dubia was much more abundant in Canagagigue Creek. Both species fed most frequently on Chironomidae and Oligochaeta, with the total variety of prey consumed reflecting the diversity of prey available at the site. The habitat preferences of the leeches were apparent from their diets: D. dubia ate relatively more animals associated with riffle habitats; E. punctata ate relatively more pool-dwelling organisms. The greater abundance of D. dubia at our study sites is attributed to this difference in habitat preference.
Prey selection by the predatory leech Nephelopsis obscura in relation to three alternative models of foraging
Authors: Anholt Bradley
Published: August 2008

Prey selection by a predatory leech, Nephelopsis obscura, was examined in a series of laboratory experiments. Two chironomids, Glyptotendipes paripes and Chironomus riparius, and the tubificid worm, Tubifex tubifex, were used as alternative prey. These three prey are all tube dwellers found in the same microhabit at the mud–water interface. The quality of each of the three prey types was estimated by their ability to promote the growth of the leeches. The two chironomids were much superior prey than Tubifex. Mixed diets did not improve growth. The selectivity of starved leeches offered equal densities of the two chironomids was not affected by the absolute abundance of prey. After 72 h the selectivity was biased toward Chironomous, the more mobile prey, and this bias increased with prey density. Varying the relative abundance of these two prey did not alter the selectivity of the leeches with a single exception. When Chironomus was the more abundant prey, selectivity was biased towards it, but this disappeared after 72 h. There were no significant effects of absolute abundance, relative abundance, or feeding history on the selectivity of leeches offered a choice between Glyptotendipes and Tubifex. Tubifex was rarely captured in any of the treatments tested. It was concluded that a description of prey choice by Nephelopsis does not require explanations based in optimal diet theory or frequency-dependent foraging. Differences in capture rates of different prey species may be related to their motility or vulnerability rather than any active choice on the part of Nephelopsis.
Effects of stream regulation on density, growth, and emergence of two mayflies (Ephemeroptera: Ephemerellidae) and a caddisfly (Trichoptera: Hydropsychidae) in two Rocky Mountain rivers (U.S.A.)
Authors: Perry Sue A. , Perry William B. , Stanford Jack A.
Published: August 2008

The influence of altered temperature and food regimes on the life histories of three univoltine species of aquatic insects were compared in two regulated river systems in northwestern Montana, U.S.A. Temperatures in both regulated rivers were more moderate than below many deep-release dams as a result of the operation of a selective withdrawal system on the dam on the Kootenai River and of major input of waters from unregulated forks in the Flathead River. Population densities of these species were generally highest in the regulated Kootenai River where the greatest biomass of periphyton and seston were measured. Differences in growth rates between regulated and reference stations were observed for Drunella flavilinea and Hydropsyche oslari but not for Serratella tibialis. Temperature had little effect upon total developmental time for H. oslari but altered growth rates and time spent in late instars. Peak emergence times were 2 to 4 weeks later in regulated areas where summer water temperatures were cooler, and the duration of emergence periods was extended in regulated areas.
The timing and direction of food flights from an inland great blue heronry
Authors: Forbes L. Scott
Published: August 2008

The temporal distributions of arrivals and departures of Great Blue Herons (Ardea herodias) at a colony in southeastern British Columbia differed significantly from a Poisson distribution (p < 0.001). The directions of herons arriving > 2 and ≤ 2 min apart were not significantly different (p > 0.20). However, herons departing ≤ 2 min apart flew in the same direction significantly more often (p < 0.005) than herons departing > 2 min apart. The two strongest hypotheses to account for this behaviour, flock recruitment and information centres, are the product of social interaction.
Nitrogen excretion by embryos of a gallinaceous bird and a reconsideration of the evolutionary origin of uricotely
Authors: Packard Gary C. , Packard Mary J.
Published: August 2008

Small amounts of ammonia and urea were present in freshly laid eggs of Japanese quail (Coturnix coturnix), but neither substance increased appreciably in quantity during the 17 days between oviposition and pipping. In contrast, urate was not detected in eggs before day 10 of incubation, but accumulated rapidly thereafter. Over 90% of the waste nitrogen accumulating in eggs between days 0 and 17 was in the form of urate, thereby demonstrating that embryos of this precocial bird are uricotelic. If ammonia released in the catabolism of amino acids had been converted to urea instead of to uric acid, the concentration of urea inside eggs presumably would have been sufficient by day 15 of incubation to inhibit metabolism of developing embryos. The evolutionary transition from ureotely to uricotely among ancestors of birds may, therefore, have been driven by selection for a mechanism to remove a potential source of inhibition to metabolism and growth of embryos.
Genetic changes in an irradiated population of wild meadow voles (Microtus pennsylvanicus)
Authors: Ross Howard A.
Published: August 2008

Changes observed in the genetic structure of a wild population of meadow voles (Microtus pennsylvanicus) exposed to chronic gamma radiation are compared with those observed in a nearby unirradiated population. An average exposure of 14.6 ± 0.8 mGy/d of gamma radiation was administered from a 137Cs field irradiator to an otherwise unmanipulated population over 47 weeks. The demographic and genetic characteristics of the populations were estimated by livetrapping and by electrophoresis of the polymorphic plasma proteins encoded by transferrin and leucine aminopeptidase, respectively. Both the irradiated and control populations showed highly synchronous demographic changes: an autumn decline, very low density throughout the winter, a late spring increase, and late summer peak. Allele frequencies and F-statistics fluctuated dramatically throughout the low-density phase. Coincident with the acceleration of population growth, the genetic variables began to converge in the two populations. At the termination of the experiment, when population growth was slowing, the irradiated and control populations were genetically very similar. Sexual activity, longevity, and recruitment were each homogeneous among genotypes in both populations. The radiation treatment had no apparent effect on the genetic structure of the vole population. Gene flow at the beginning of an increase phase is suggested as a possible cause for convergence of the genetic attributes of the irradiated and unirradiated populations.
Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated CO2 in a simulated winter microhabitat
Authors: MacArthur Robert A.
Published: August 2008

Metabolic and behavioral responses to inspired CO2 were investigated in muskrats housed in a microhabitat designed to simulate winter field conditions. Mean daily rate of oxygen consumption [Formula: see text] declined from 1.46 mL O2∙g∙h−1 in animals breathing room air to 1.11–1.25 mL O2∙g∙h−1 in animals inhaling 4–10% CO2 in the simulated lodge. Daily patterns of [Formula: see text], abdominal body temperature (Tb), and foraging activity were minimally affected by chronic CO2 exposure, though muskrats breathing 9–10% CO2 made shorter voluntary dives. The ability of muskrats to rewarm following foraging activity was slightly depressed by hypercapnia. Abrupt exposure of resting animals to ambient CO2 levels of 10–16% often elicited avoidance reactions in the absence of any apparent change in [Formula: see text] or Tb. This study provides the first demonstration of behavioral and metabolic responses by muskrats to CO2 levels encountered in the winter microhabitat of this species.
Ovarian cycle and plasma concentrations of estrogen and vitellogenin in brook trout (Salvelinus fontinalis, Mitchill)
Authors: Tam W. H. , Roy R. J. J. , Makaran R.
Published: August 2008

Oocyte development and plasma concentrations of estrogen and vitellogenin in brook trout have been investigated. Oocyte development and vitellogenesis resumed immediately after spawning in October, but, up until May, oocytes never developed beyond 1000 μm diameter and yolk deposition only resulted in the appearance of a relatively modest number of fine droplets and globules. A peak occurrence of atretic follicles of about 900μm diameter was observed in March. In May, many cortical alveoli stage oocytes were seen developing from perinucleolar oocytes. From June to October, oocyte growth and vitellogenesis occurred at a faster rate. By the time of ovulation, the oocytes were about 2500 μm in diameter and became filled with a homogeneous mass of yolk. Throughout winter and spring, plasma level of estrogen was 1–5 ng/mL and that of vitellogenin was mostly below 5 μg/mL of alkali-labile protein phosphorus. In October, the plasma concentrations of estrogen and vitellogenin increased to 40 ng/mL and 96 μg/mL, respectively.
Ultrastructural localization of IgA and IgG receptors on oocysts, sporocysts, sporozoites, and merozoites of Eimeria falciformis
Authors: Whitmire W. M. , Speer C. A.
Published: August 2008

The localization of parasite-specific IgA and IgG immunoglobulins on Eimeria falciformis oocysts, sporocysts, sporozoites, and merozoites was examined by immunoelectron microscopy. Parasites were fixed in glutaraldehyde, incubated with heat-inactivated sera or gut contents from normal or specifically immunized mice, reacted with ferritin-conjugated or colloidal gold-conjugated sheep or goat antimouse IgA or IgG antibody and prepared for transmission electron microscopy. Other purified samples of sporozoites or merozoites were exposed to sera or gut contents, fixed in 0.15% glutaraldehyde, and then incubated with ferritin-conjugated or colloidal gold-conjugated sheep or goat antimouse antibody. Parasite-specific IgA and IgG receptors were detected on the plasmalemma of sporozoites and merozoites. Specific IgG receptors were also present on the inner and outer layers of the oocyst wall, and on the inner surface of the sporocyst wall. Live sporozoites and merozoites shed immune complexes at their posterior ends. No internal alternations were detected ultrastructurally in sporozoites or merozoites treated with parasite-specific IgA or IgG antibodies.
Microtine population dynamics in a predictable environment
Authors: Negus Norman C. , Berger Patricia J. , Brown Bruce W.
Published: August 2008

A noncycling population of Microtus montanus was studied for 8 years in a marsh community in Utah. Seasonal climatic and vegetational regimes were very similar each year. The food resource for voles in this habitat was almost solely salt grass (Distichlis stricta). Each year, salt grass began sprouting in late February and, several weeks later, most of the females were pregnant with their first litters. By August of each year, the salt grass had flowered, fruited, and was senescing; likewise, breeding had ceased by the end of August. Each year, four cohorts of young were produced between April and late August. Analysis of cohort life histories revealed that cohorts I and II matured rapidly and reproduced later in the same season. Cohort III animals grew very slowly, overwintered as subadults, and formed the primary breeding stock the following spring. Overwintering survival of cohort III animals was much higher than that of cohorts I and II. By the end of the breeding season each year, densities ranged between 150 and 225 animals/acre (1 acre = 0.405 ha). Densities at the end of winter varied between 50 and 120 animals/acre. The rate of population increase from April to August each year was virtually identical. Thus, the August densities were very strongly correlated with each preceding April density. The predictable seasonal phenology and uniform timing of cohort production each year seems to explain the yearly attainment of high density. Comparison of these data with studies of fluctuating populations of M. montanus in montane environments leads to the conclusion that the unique life history of each microtine cohort coupled with unpredictable environmental regimes may generate large-scale density oscillations. If this concept is valid, then microtine population dynamics are not cyclic at all, but rather pseudoperiodic.
Comparison of the DNA of nuclei of rodlet cells and other cells in the chub Semotilus atromaculatus: hybridization in situ
Authors: Barber D. L. , Westermann J. E. Mills
Published: August 2008

With nick-translated genomic DNA of the northern creek chub, Semotilus atromaculatus, DNA–DNA hybridization of rodlet cells and cells known to belong to this species showed the same degree of labeling in the nuclei. The amount of hybridization for all cells was greater than that seen in chub cells treated with rainbow trout genomic DNA and than that found when other teleost, amphibian, human, or protozoan cells were treated with chub genomic DNA. Washing experiments at different temperatures also showed that the stability of the hybrids was comparable for both cell types. As a result, the nuclei of rodlet cells in this species are considered to contain qualitatively the same DNA as cells known to belong to the fish, and the rodlet cell itself, therefore, is of teleost origin.
Meteterakis vaucheri n. sp. (Nematoda; Heterakoidea) from Varanus grayi (Varanidae) in the Philippines
Authors: Adamson Martin L.
Published: August 2008

Meteterakis vaucheri n. sp. from the posterior intestine of Varanus grayi from Dipaculao, Province of Aurora in the Philippines, differs from all other species in the genus except M. louisi in having spicules over 1 mm long. It differs from this latter species by the form of the spicules and by the fact that the caudal alae of the male are supported by three, rather than four, pairs of pedunculate papillae. In addition, several characters observed in the new species have not been reported previously in the genus: (i) small oval cuticular plates (amphidial plates) immediately anterior to the amphids; (ii) subventral extensions to the caudal alae of the males and; (iii) a blind diverticulum near the midregion of the seminal vesicle. The diagnostic value of these characters is uncertain.
Studies on monogeneans and copepods parasitizing the gills of a sparid (Acanthopagrus australis (Günther)) in northern New South Wales
Authors: Roubal Frank R.
Published: August 2008

Degree of host tissue response to monogenean (Lamellodiscus acanthopagri, L. major, L. squamosus, Haliotrema spariensis, Polylabroides multispinosus) and copepod (Ergasilus sp., Lernanthropus atrox, Alella macrotrachelus) parasites on the gills of Acanthopagrus australis varied with developmental stage and among species. The histophagous ancyrocephalines L. acanthopagri and L. squamosus and the sanguinivorous polyopisthocotylean P. multispinosus elicited no host response. In contrast, phylogenetic relatives of the former two species, L. major and H. spariensis, were associated with extensive hyperplasia of the filament. Among the copepods, Ergasilus sp. elicited a minor response. However, larval, subadult, and adult A. macrotrachelus were associated with increasing extents of filament alteration. Similarly, adult L. atrox were associated with massive hyperplasia which often included adjacent filaments. The observed variability in tissue response is discussed in terms of parasite attachment, mobility, and feeding strategies.
Evidence for displacement of a North American spider, Steatoda borealis (Hentz), by the European species S. bipunctata (Linnaeus) (Araneae: Theridiidae)
Authors: Nyffeler Martin , Dondale C. D. , Redner J. H.
Published: August 2008

The European spider Steatoda bipunctata has apparently been introduced into North America through human transport. The earliest American collections were made in Nova Scotia in 1913. Until about 1933, specimens were known only on the coast of the Atlantic provinces, Maine, and along the St. Lawrence River and Lake Ontario, but they are now found widely in the Atlantic Provinces, northernmost New England, and southern Québec and Ontario. Habitats include buildings, bridges, piles of lumber and firewood, and crevices on tree trunks or among rocks. Evidence indicates that S. bipunctata, which closely resembles the native S. borealis in size, colour, microhabitat, diel activity, prey selection and utilization, life history, and sexual behaviour, can displace S. borealis. Displacement is, however, only partial, as S. borealis persists in forest habitats, where human influence is minimal. Laboratory tests on reproductive potential and interspecific aggression failed to demonstrate the method by which displacement takes place.
Geographic variation in wing melanism of the butterfly Parnassius phoebus F. (Lepidoptera: Papilionidae)
Authors: Guppy C. S.
Published: August 2008

Butterflies from higher elevations and latitudes are often darker than populations from low elevations and latitudes. This "alpine melanism" may be an adaptation to colder environments and may be correlated with smaller size. I quantified geographic patterns of variation in wing melanism and size for the butterfly Parnassius phoebus to determine if individuals from populations living at higher elevations and latitudes are smaller and more melanic. The ratio of black to white scales in the basal area of the hind wings is well correlated with the elevation, latitude, and mean air temperature of a population. This suggests that variation in that component of wing melanism is the result of adaptation to different thermal environments. The width of the predominantly black patch in the basal area of the hind wings of males is correlated with elevation, latitude, and air temperature, suggesting that variation in this character may also have a thermoregulatory significance. In the distal area of the front wings, wing transparency and the extent of black scaling are correlated with elevation on individual mountains, but are not correlated with elevation when populations from many mountains are considered together. Other environmental factors correlated with elevation, such as predation, may be more important than thermal effects in determining variation in melanism of the distal area of the wings of P. phoebus. The positive correlation between size and mean air temperature during the flight period is significantly weaker than the negative correlation between size and elevation, suggesting that thermoregulatory considerations can not account for variation in size between populations.
Fine structure of sensilla on the ovipositor of the tephritid fly Urophora affinis
Authors: Zacharuk R. Y. , Lee R. M. K. W. , Berube D. E.
Published: August 2008

There are four types of sensilla on the ovipositor blade of Urophora affinis Frauenfeld, one more than was observed on three other species of fruit flies studied by other authors. Three of the types, uniporous gustatory pegs, campaniform organs, and tactile short hairs are common to the four species and generally are in similar positions on the blade. The fourth, uniporous gustatory plates, were noted in U. affinis only. The chemosensilla are innervated by three chemosensory dendrites that terminate below the pore and a mechanosensory dendrite with a tubular body that is attached to a basal cuticular apodeme of the covering cuticle. The dendritic tubular bodies of the campaniform organs and tactile hairs terminate parallel to the surface in a right-angular bend, where they are attached to basal apodemes of the covering cuticle. The chemosensilla and tactile hairs have individual outer and inner sheath cells, but the campaniform organs have individual inner sheath cells only. The part of the ciliary dendritic segment that is encased by the dendritic sheath passes through an epidermal cell, often with several sensilla sharing the same epidermal cell in place of an outer sheath cell. The role of these sensilla during oviposition is discussed.