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  • Articles  (7)
  • 1990-1994  (7)
  • Biology  (5)
  • Medicine  (2)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
  • Energy, Environment Protection, Nuclear Power Engineering
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  • Articles  (7)
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  • 1
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The factors influencing the seasonal and inter-annual variations in the numbers of Daphnia hyalina in Esthwaite Water between 1956 and 1972 are analysed. Esthwaite Water has always been eutrophic. but the phosphorus and nitrogen loadings to the lake increased significantly in the mid 1960s.2. Qualitatively, the phytoplankton and zooplankton populations in the lake changed relatively little during the period of study. Quantitatively, however, eutrophic species of algae became more abundant and the numbers of Eudiaptomus declined as the numbers of Daphnia increased.3. The seasonal dynamics of the Daphnia was governed partly by the seasonal temperature cycle, and partly by the periodicity of edible algae. The birth rate of the Daphnia was constrained by temperature from January to April and from October to December. At other times their rate of increase was governed by the relative abundance of edible and inedible algae.4. Edible and inedible species of algae tended 10 appear in a recurring annual sequence. Diatoms such as Asterionella were abundant in the spring, the early summer phytoplankton was dominated by edible flagellates, but inedible algae such as Aphanizomenon and Microcystis become dominant later in the year.5. Daphnia could only reproduce in late summer when there were periodic regrowths of edible algae. Such regrowths were most likely to occur when there had been some entrainment of deep nutrients by episodic wind mixing. Calm weather encouraged the growth of blue-green algae that effectively‘blocked’the development of the Daphnia for the remainder of the summer.6. The factors that controlled the seasonal dynamics of the Daphnia also influenced the average number recorded in a particular year. The average number of Daphnia increased in the early sixties when Cryptomonas was abundant and decreased in the late sixties when blooms of Aphanizomenon appeared in mid summer. Detailed analyses showed that a similar increase in the numbers of Aphanizometion had occurred in the late fifties. The critical factor throughout was the prolonged period of calm resulting in stable stratification.7. This ‘weather’ effect was highlighted by comparing de-trended timeseries of Daphnia and Aphanizometion numbers with a simple measure of thermocline stability. De-trending removed the superimposed effects of progressive enrichment and revealed a 10-year cycle of thermocline stability that matched the temperature cycle recently reported in Windermere, These cycles are related to the movement of weather systems in the Atlantic so could change if the pattern of atmospheric circulation is altered by global warming.8. The possible effects of climate change on Daphnia dynamics are discussed in relation to the findings in Esthwaite Water.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 37 (1990), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Variation in growth rate, age at maturity, reproductive life span and reproductive investment was investigated in females only in seven populations of roach, Rutilus rutilus, in Norway. The growth rates of mature female roach were low, varying for most populations between 10 and 14 mm year.1 At the most northern locality the growth rate was only 5.6 mm year1. Individual fecundity and gonadosomatic index (GSI) varied unsystematically between populations, but it was evident that the population with the lowest growth rate also had the lowest individual fecundity and GSI. Egg weight also varied between populations, the most northern population had a medium egg weight, thus, in harsh climatic conditions egg number is sacrificed for a relatively high egg weight. We found no further evidence for a trade-off between egg number and egg size. Fecundity increased with length in all populations, whereas the variation in egg size and GSI for most populations did not covary with length or age. This fact, together with the high age at maturity in all populations and the long reproductive life spans supports the bet-hedging theory of life-history evolution. This is further supported by the fact that we did not find any correlation between the growth rates and the different descriptors of fitness.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 37 (1990), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We studied reproductive traits in nine anadromous brown trout, Salmo trutta L., populations in seven Norwegian rivers. Within populations we found a positive significant correlation between fish length and fecundity in all populations, and between fish length and egg diameter in five populations. There were significant differences in these relationships between populations from different rivers, and between populations from different locations within rivers. When adjusted for variation in fish length, mean fecundity and mean egg diameter showed a negative significant correlation among populations. The ratio of gonadal weight to somatic weight (gonadosomatic index) varied significantly among populations but was not associated with variation in fish length. Comparatively few large eggs were found in brown trout populations co-existing with several other fish species.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 43 (1993), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Based on published data, we reviewed clinal variations in life-history characteristics of anadromous brown trout Salmo trutta from 102 European rivers at latitudes between 54 and 70° N. Growth rate in fresh water, mean smolt age, mean sea age at first sexual maturity, proportion of repeal spawners among adults, longevity, and length of adult life span exhibited latitudinal clines. Brown trout grew faster in fresh water, smolted and matured younger, lived fewer years but spawned more times in the south than in the north. The life-history traits studied were often correlated. Longevity, smolt age and sea age at maturity were negatively and smolt length and proportion of repeat spawners among adults were positively correlated with growth rate in fresh water. Longevity was positively correlated with smolt age and sea age at maturity. The latter also increased with increasing smolt age. None of these significant correlations among life history variables, except for those between smolt age and parr growth and proportion of repeat spawners and parr growth, are latitudinal effects. We do not know to what extent the latitudinal variation in life–history traits reflects phenotypic plasticity and to what extent it is caused by inherited differences among populations.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 41 (1992), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Size and frequency of occurrence of prey of brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.) were recorded in 13 Norwegian lakes during 1973–1990. Piscivores usually comprised less than 5% of the total population. Arctic charr were less piscivorous than brown trout. Trout and charr became piscivorous at 13 and 16 cm length, respectively. These size thresholds were similar to those of other facultative piscivorous freshwater fish species. When present, three-spined sticklebacks, Gasterosteus aculeatus (L.), were preferred by all length groups of piscivorous brown trout and Arctic charr. Length of prey increased with increasing predator length, and the mean body length of prey was about 33 and 25% of predator length for trout and charr, respectively. Yearlings of charr were not recorded as prey.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 41 (1991), S. 351-354 
    ISSN: 1432-1041
    Keywords: Paroxetine ; Cirrhosis ; pharmacokinetics ; multiple-dose study ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a 14-day multiple-dose study the pharmacokinetics of paroxetine was investigated in 12 patients with alcoholic cirrhosis and in 6 subjects without liver disease. The dose of 20–30 mg paroxetine daily was adjusted to the reduction in liver function, as assessed by the galactose elimination capacity. Accordingly, all but two of the cirrhotic patients received 20 mg, while all six control subjects received 30 mg. Dose-corrected, trough drug concentration at steady state (CSS min) and dose-corrected AUC24h were significantly higher in the patients with liver diseases than in the control subjects [3.4 vs 1.5 ng · ml−1 per mg paroxetine and 89 vs 43 h (ng) · ml−1 per mg paroxetine]. The elimination t1/2 was prolonged [83 vs 36 h], but the difference was not statistically significant, and the cirrhotic patients were still able to clear almost all the paroxetine by metabolism. All but two patients with cirrhosis experienced nausea during the first two or three days after the first dose, while none of the controls had this symptom. The study showed slower elimination of paroxetine and consequently higher plasma levels in patients with cirrhosis, suggesting that in the latter the dose of paroxetine should be in the lower end of the therapeutic range.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1991-10-01
    Print ISSN: 0031-6970
    Electronic ISSN: 1432-1041
    Topics: Chemistry and Pharmacology , Medicine
    Published by Springer
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