ASPECTS OF LIFE CYCLE, POPULATION DYNAMICS, GROWTH AND SECONDARY PRODUCTION OF THE PULMONATE SNAIL CEPAEA VINDOBONENSIS (FÉRUSSAC, 1821) IN NORTHERN GREECE

Abstract

The life cycle, population dynamics, growth and secondary production of the land snail C. vindobonensis were studied in northern Greece. Demographic analysis of the populations of C. vindobonensis revealed that a) three cohorts were present in the field throughout the year, b) the reproductive period started in late April-May and the newly hatched snails appeared in the beginning of June, and c) increased growth rates were observed during spring and early summer, but also during autumn for the newly hatched snails. According to von Bertalanffy's method C. vindobonensis needs 7 years to attain its maximum size measured in the field. Mortality rate is very high during the first year of life, while life expectancy is higher during the second year of life and decreases afterwards. Net reproductive rate (R,,) was equal to 3.1 and the finite capacity for increase (antilogy,.) was equal to 1. Estimated annual secondary production with Hynes' frequency method revealed a mean standing crop (B) of 0.99 g/m2/year and a production (P) of 1.3 ± 0.11 g/m2/year. Annual turnover ratio (P/B) was equal to 1.31.