On the population dynamics, reproductive biology and growth of Succinea putris (Linnaeus, 1758) (Gastropoda: Pulmonata: Succineidae)

Abstract

Selected life-cycle and population parameters of acommonEuro-Siberian wetland snail – Succinea putris (L.) – were studied in the field and in the laboratory. In the field the snails reproduced at least from April till Sep- tember, with April–May and August–September peaks; only one such peak (April) was observed in the laboratory, though the snails reproduced throughout the year. The changes in population size structure in the field and the laboratory results (life span 210–420 days, mean 309) indicated semelparity. Growth in the laboratory included two phases: slow (November–March) and fast (June–October); which phase came first during the life cycle depended on the date of hatching. The growth rate in the field corresponded closely with the fast-phase growth in the labora- tory. The smallest reproducing individual was slightly over 2.8 whorls; snails of 3.0 whorls were regularly observed to produce eggs (maximum number of whorls in adults: 4.0). Sexual maturity was attained in ca. 160 days. The eggs (non-calcified, translucent, spherical, 1.7–2.0mmin diameter) were laid in batches, 5–64 per batch; the eggs within a batch were glued together. The batch dimensions were 3.5–25.7×2.2–24.7 mm. The time to lay a batch was 20–35 minutes. Forty-eight snails produced 74 batches within 12 months. The duration of the egg phase was 11–28 days, which might indicate egg retention of varied duration; hatching was asynchronous, spanning 1–12 days within a batch. The hatchlings had shells of 1.1–1.2 whorls; hatching success was 95%. Neither uniparental repro- duction, nor egg or juvenile cannibalism were observed. When compared to data in the literature, our results im- ply that Succinea putris displays substantial local variation in life-cycle traits.We also provide an overview table to dis- cuss similarities and adaptive radiation in the European succineid species. KEY