Comparative analysis of the growth of Margaritifera margaritifera (Bivalvia) from different populations of Karelia and Kola Peninsula

Comparative analysis of individual linear growth of Margaritifera margaritifera populations from the Syuskyuyanioki, Nemina, Vuokinioki, Keret (Karelia), and Varzuga (Kola Peninsula) rivers has been performed. Data on the lengths of consecutive annual growth rings on the external shell surface have been obtained. The comparative analysis has been made of two coefficients of the united growth equation, one of which determines the initial growth rate; the other determines growth inhibition. Growth parameters are assumed to vary greatly within each population and differ significantly between different specimens. The values of the coefficients decrease with increasing geographical latitude of the habitat. It is shown that the population in the Syuskyuyanioki River is comparable with respect to the growth constant with the southernmost populations of rivers in Northern Spain.