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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 8 (1978), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Oligochaete worms dominate the macroinvertebrate fauna of the River Irwell, in north west England. The river is polluted by domestic and industrial wastes. Tubificids constituted 86.8% of the worm fauna, with three dominant species; Tubifex tubifex (Müller), representing 43.1% of the total oligochaetes, Limnodrilus hoffmeisteri Claparède, representing 26.8% and Limnodrilus udekcmianus Claparède, representing 16.7%. The Naididae were the next most abundant worms, representing 6.1% of the oligochaete fauna, with Nais elinguis Müller comprising 5.0%. T. tubifex and L. hoffmeisteri were abundant along the length of the river, but reached their greatest numbers in the organically polluted lower reaches at Agecroft and Salford. The density of L. udekemianus was low in the Irwell above the entry point of the heavily polluted River Roch, but high below this point. N. elinguis was abundant above the Roch entry point and scarce below it.In the three dominant tubificids, the main population recruitment occurred during the summer months (April to September for T. tubifex, May to November for L. hoffmeisteri and June to October for L. udekemianus). In N. elinguis, there was massive recruitment in April.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 26 (1972), S. 30-41 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A brief summary of observations of inhomogeneities in the solar atmosphere and progress in the theoretical analysis of two-dimensional model atmospheres is given. In particular, it is asserted that reliable reference models of the mean temperature, pressure, etc. may be derived only by averaging over the horizontal coordinates of a two- or three-dimensional model. In discussion of a wide variety of cases including strong chromospheric lines, weak photospheric lines, and continuum radiation, it is shown that although the derivation of mean values by first averaging over the fluctuations in the data and then applying a one-dimension analysis is an obvious first approximation, it may lead to errors of a gross qualitative nature. Thus the recent deductions by several authors of very small temperature gradients in the upper regions of sunspots are shown to be subject to considerable doubt.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The intrinsic rate of natural increase, rm, of the planorbid snail Biomphalaria pfeifferi, was estimated in a series of culture media with differing concentrations of calcium bicarbonate. These gave a range from very soft to distinctly hard water. 2. rm values were obtained from cohorts of snails from two widely separated streams, in different catchments, and these were compared with results obtained by Williams (1970b) from a third stream. All three were near Salisbury, Rhodesia, but they had markedly different calcium bicarbonate concentrations. 3. Snails from all three demes gave a similar pattern of rm values and highest values were obtained from a culture water containing 12 mg/l of calcium as Ca++, and 35 mg/l bicarbonate as CaCO3, here classified as water of ‘medium’ hardness. This was in spite of the fact that two of the demes came from distinctly harder water. 4. Apart from this overall similarity the three demes showed differences in egg-laying and survivorship patterns. 5. The significance of these results is discussed.
    Type of Medium: Electronic Resource
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