Observations on the Maturation and Development of a Roman Snail (Helix Pomatia, Linnaeus, 1758) Population of Farmed Origin in Natural Plots

Abstract

Abstract Observations were made concerning active species protection of the Roman snail. Samples were collected from three natural plots in which 3,000 marked hatchlings of farmed origin, aged 1+ (three individuals per m2), were placed in mid-May 2011. The hatchlings originated from breeding snails of the park, or ‘source’ plot. The other plots were a forest, or ‘inhabited’ plot, occupied by a foreign population and a cultivated ‘empty’ plot, which had been emptied of its natural population. By the end of June 2012, the introduced snails were aged 2+, when snails of this species reach maturity. During this period, as part of the analysis of collected samples, the snails in their final maturation period in this age group were divided into mature and immature groups. After thirteen months of observations, a greater density was observed for the farm-originated, naturalised population in the ‘empty’ plot than in the total populations for the other two plots. In the ‘empty’ plot the percentage of somatic and sexually mature farmed snails aged 2+ was significantly higher than in the same snail groups from the other two research plots. There were no statistically significant differences between the shell diameters of the mature farmed snails in all the research plots. The Roman snails of farmed origin considerably extended their territorial range, maintaining their high percentage share in the local natural populations.