ISSN:
1573-5117
Keywords:
Diaptomus gracilis
;
exponential heating by radiation
;
redox potential
;
stagnation
;
thermistor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Temperature, selected chemical constituents and plankton were analysed from three depths, fortnightly, by day and occasionally by night, in two flooded brickpits, between May 1930 and August 1931. Br was 3.3 m deep, with clear water and little weed; III was only 1.8 m deep, with thick submerged weed, more sheltered than Br and becoming eutrophic. Neither had direct inflow nor outlet. Both conformed to the second order for dimictic lakes, with summer and winter stratification, leading, for varying periods, to stagnation marked by pH between 6.6 and 7.2 and O2 much depleted or absent at the bottom. During stagnation, release of SiO2, soluble inorganic phosphate-P, ammonium ions and bases from the bottom was shown by sampling water close to the mud. This finding preceded the definition of ‘redox potential’ by others. Thermistor temperature measurements, used for the first time, showed comparable summer gradients in both ponds: on windy days these were usually sigmoid, with discontinuity at various depths, or else nearly isothermal; on calm days, they were exponential, when transmission of heat, from surface to bottom, was apparently due to radiation alone, without water circulation. Stability was then high. Diatoms were abundant in both ponds; but planktonic Rotifera and Crustacea differed in the two, apart fromDiaptomus gracilis, which was dominant in both.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00014958
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