Lake Baikal is the oldest and deepest (1700 m) freshwater lake on earth. The lake is characterised by a large number of species, most of them endemic. The main feature of baicalean gastropods is their thin shell (Kozhov, 1963). All phylogenetically related, palaearctic species have thicker shells. Kozhov (1963) concluded that calcium is the limiting factor because of very low calcium concentrations in the water of Lake Baikal (402 µmol/l, Falkner et al., 1991). This point of view is controversial, because other investigations show no correlation between external calcium concentration and shell thickness (Burky, 1983).
Our aim is therefore to eludicate the influence of water chemistry and temperature on calcium metabolism. In addition, we are planning to compare the findings with results from phylogenetically related species. The following parameters are under investigation:

• Calcium content of various tissues (Flame-Atomic-Absorption-Spectrometer: F-AAS)
• Amount of concretions (granulous storage sites for calcium; Brown, 1982) in various tissues (F-AAS)
• Metabolic rate at different temperatures (Kalorespirometry: Oxygen comsumption, heat production)
• Ionic composition of the hemolymph (Ion-Capillary-Electrophoresis)

Literatur
Brown BE, 1982: The form and function of metal-containing "granules" in invertebrate tissue. Biol. Rev. 57: 621-667.
Burky AJ, 1983: Physiological ecology of freshwater bivalves. In: Wilbur (ed.): The Mollusca, Vol. 6, 281-327.
Falkner KK, Measures CI, Herbelin SE, Edmond JM, Weiss RF, 1991: The major and minor element geochemistry of Lake Baikal. Limnol. Oceanogr. 36 (3): 413-423.
Kozhov M., 1963: Lake Baikal and ist life. Monographiae Biologicae. Dr. W. Junk Publishers, The Hauge.
 

LECTURE-ABSTRACT
(DZG-Kongress 1999, Innsbruck, Austria)