Population dynamics of the Carpathian clausiliid Vestia gulo (E. A. Bielz 1859) (Pulmonata: Clausiliidae) under various climatic conditions

Population dynamics of the hygrophilous, egg-retaining clausiliid Vestia gulo was studied in the Carpathians (Poland) over three years at four sites that differ in their temperature regime. Juveniles (2.5 whorls) hatched in late June and/or in July. At the highest located site (1150 m a.s.l.) juveniles reached 3.5–4 whorls in the first growing season, 5.5–7 in the second, and probably attained maturity in the third or fourth season of their life (shells with 8.3–10.1 whorls). At the intermediate site (759 m a.s.l.), snails reached 4.0–6.0 whorls in the first growing season, 7.4–9.4 in the second and completed growth with 9.0–11.25 whorls at the third growing season. At two lowest sites (both at 425 m a.s.l.) populations of Vestia gulo differed in the growth rate, consequently snails reached ultimate size in two or three seasons. In the fastest growing population in the first season juveniles grew to 5.5–8.4 whorls, then during the second growing season they reached the ultimate size (9.25–12.25 whorls). Marked adults lived at least four years. Copulations were observed in autumn; in winter, there was hardly any growth.