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  • 1970-1974  (7)
  • 1
    Digitale Medien
    Digitale Medien
    Annual production of two Nova Scotian populations of Nucella lapillus (L.) (1972)
    Springer
    Oecologia 8 (1972), S. 356-370 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary One population of Nucella lapillus, under conditions of food shortage, decreased in biomass with an annual production of 5.5 kcal per m2. The second population, with plenty of food, gained biomass and the annual production was 16.7 kcal per m2. Individuals grew faster, while attaining sexual maturity and terminating growth at a larger size in the second population. In both populations, energy produced as gametes exceeded the energy produced due to growth. A 2.56 cm female was estimated to produce 46.6 egg capsules (about 1 kcal) a year but the output of males was unknown and assumed to be half that of females. The sex ratio was equal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00367538
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  • 2
    Digitale Medien
    Digitale Medien
    Chlordiazepoxide modified exploration in rats (1972)
    Springer
    Psychopharmacology 24 (1972), S. 462-469 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Chlordiazepoxide ; Exploration ; Locomotion ; Rearing ; Novelty
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Effects of 2.5, 3.75 and 5.0 mg/kg chlordiazepoxide on locomotion, rearing and preferences for novelty in rats were observed in an exploration box comprising a novel and a familiar half. Whereas an inverted U relationship between dose strength and locomotion was evident, rearing declined with increasing dosage. However, the two lower doses had little effect on preferences for novelty but 5.0 mg/kg produced a marked decrease to the point where the familiar half of the apparatus was preferred. It was concluded that estimates of drug effects on measures of locomotion or general activity are specific to those behaviours alone and do not necessarily relate to environmentally oriented exploration. Different views of the effects of drugs on exploratory behaviour might arise from the use of more valid indices, such as preferences for novelty.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00423436
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  • 3
    Digitale Medien
    Digitale Medien
    Classification and ordination of benthic samples from Bedeque Bay, an estuary in Prince Edward Island, Canada (1971)
    Springer
    Marine biology 10 (1971), S. 227-235 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An attempt was made to identify the causes of the distribution of benthos within Bedeque Bay using multivariate techniques programmed for the computer. Both classification by a hierarchical cluster analysis, and ordination by principal components analysis suggested that a large proportion of the variance in the data was directly or indirectly correlated with a salinity gradient. Classification divided the species into two main groups, a in the upper half of the estuary where lower salinities and larger salinity fluctuations occurred, and group b in the lower half of the estuary with a more stable salinity regime. The group b species were further subdivided into those preferring soft mud and those preferring sandier sediments. The group a species were divided into a well-developed oyster association and various sub-groups less strongly associated with oysters. Five principal components were required to account for 50% of the variance in the data. The first axis accounted for 20% of the variance and was shown by a non-parametric test to be correlated with the salinity gradient. Axes II to V could not be interpreted, but possibly represented complex species interactions. By providing hard substrates and altering the natura of the sediment, oysters and mussels produced conditions suitable for many other species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00352811
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  • 4
    Digitale Medien
    Digitale Medien
    Ecological energetics of Nerita (Archaeogastropoda, Neritacea) populations on Barbados, West Indies (1971)
    Springer
    Marine biology 11 (1971), S. 12-22 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Population energy budgets estimated on the assumption of steady state conditions for Nerita tessellata Gmelin, N. versicolor Gmelin, and N. peloronta L. on Barbados, W. Indies, are presented. Large differences in population structure, and hence energetics, occurred at different localities along the beach. Relatively high proportions (81 to 88%) of the assimilated energy were lost via metabolism. Assimilation efficiencies ranged from 39 to 43%, net growth efficiencies from 5 to 13%, and ecological efficiencies from 3 to 7%. For each species, production (P), energy flow (A) and total energy consumption (C) were expressed as functions of animal size, in order to facilitate gross estimations of the energy components for other populations for which data on size-frequency and density are available. Respiration studies of all three species in the laboratory failed to detect differences between respiration rates in air or under seawater.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00348016
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  • 5
    Digitale Medien
    Digitale Medien
    Notes on the Nerita (Archaeogastropoda) populations of Aldabra Atoll, Indian Ocean (1971)
    Springer
    Marine biology 9 (1971), S. 290-299 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nerita undata, N. plicata, N. polita, N. albicilla and N. textilis are common intertidal gastropods on Aldabra Atoll. Each species prefers a different level on the shore and/or different degrees of exposure to wave action. Patterns of zonation, population size-frequency structure and biomass are given. N. undata exhibits 2 distinct ecophenotypes. Normal types occur on expsed to moderately sheltered shores but are replaced by ‘type B’ in extremely sheltered conditions. Differences in shell morphology and population structure are also noted. Foraging by all species was confined to hours of darkness, generally at low tide. Activity of N. polita was induced slightly on overcast days. N. undata and N. textilis are cryptically coloured and often visible during the day. N. plicata is conspicuous, but is protected by a strong shell. N. polita and N. albicilla are often brightly and variably coloured, but both are concealed during daylight. No Nerita were found infected with trematodes, suggesting that the degree of infection was extremely low. Habitats of the Aldabran Nerita are compared with 3 species on Barbados, West Indies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00372823
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  • 6
    Digitale Medien
    Digitale Medien
    The effects of scopolamine on performance on a geometric progressive ratio schedule (1974)
    Springer
    Psychopharmacology 38 (1974), S. 55-66 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Scopolamine ; Anticholinergics ; Cholinergic Blockade ; Progressive Ratio ; Rats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rats were trained to respond on a geometric progressive ratio schedule until performance was stable. They were then injected with the anticholinergic drug scopolamine at doses of 0.05, 0.1, 0.25, 1.0 and 2.0 mg/kg. Control animals were administered atropine methyl nitrate (1–20 mg/kg). Increasing doses of scopolamine typically produced first an increase, then a decrease in behavior compared with baseline levels, measured by total number of responses, total number of reinforcements, and final completed ratio, per session. Atropine methyl nitrate had no effect on the behaviour of the control animals. This indicates that the effects of scopolamine are due to its central action. The inverted-U dose-response curve found for scopolamine resembles that found for chlordiazepoxide, phenobarbital, and d-amphetamine on progressive schedules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00421287
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  • 7
    Digitale Medien
    Digitale Medien
    The role of social isolation and sex in determining effects of chlordiazepoxide and methylphenidate on exploratory behaviour (1972)
    Springer
    Psychopharmacology 27 (1972), S. 359-366 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Isolation ; Sex Differences ; Chlordiazepoxide ; Methylphenidate ; Exploration ; Locomotion ; Rearing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Effects of two doses each of chlordiazepoxide and methylphenidate on exploration, locomotion and rearing were observed in isolated and grouped male and female rats. Sex of the animals determined the effects of both drugs on rearing, and of chlordiazepoxide on preferences for the novel half of an exploration box. Drug administration seemed to abolish initial sex differences on the former response. Locomotion of isolated and grouped animals was also differentially affected by chlordiazepoxide. These findings emphasised the need to take genetic and environmental factors into account when considering the effects of psychotropic drugs on exploratory behaviour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00429389
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