ISSN:
1573-5117
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
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.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00035330
