Zoological Institute, Russian Academy of Science, Universitetskaya nab. 1, St.-Petersburg 199034, Russia

Abstract

Some ecologo-physiological and productivity characters of Lithoglyphus naticoides and Theodoxus astrachanicus - intermediate hosts of larvae of parasitic worms - were studied. Allometric equations connected the mass of molluscs with the length of shells were calculated on the base of linear-mass measurements. The rate of oxygen consumption, type of growth, daily specific rate of growth and average productivity were determined for populations of different biotopes. The comparison of metabolic rate of Th.astrachanicus and other molluscs that cover six-times ranges of size clearly shows the similarity in levels of energy metabolism. Power coefficient in the equation of oxygen consumption rate in dependence of mass for L.naticoides invased by trematods larvae is considerably lower then that of not invased Th.astrachanicus and other molluscs. The author suggests that invasion as one of reason can explain the regression of metabolism intensity in the process of growth. This peculiarity of energy metabolism can also be an adaptive feature and can be connected with adaptation to parasitic invasion. The equations described metabolism dependence of mass were applied for calculation of parameters of S-shape growth curve. Comparison of growth equations based on physiological and empirical data shows that theoretical S-shape curve satisfactory reflected the growth in nature and can be used for calculation of specific daily production.