Life cycle of Valvata piscinalis (O. F. Müller, 1774) (Gastropoda: Heterobranchia) in the laboratory

Abstract

Laboratory and field observations in 1994-2004 made it possible to ascertain the following parameters of life cycle of Valvata piscinalis (O. F. Müller, 1774). In favourable food conditions (filamentous diatoms) female maturity was attained in 42-85 days from hatching (mean 59 days) at the body whorl diameter of 3.45-4.65 mm (mean 4.10 mm) and the number of whorls 3.25-3.75 (mean 3.53). In slightly less favourable food conditions (periphyton) the maturity was attained later at a somewhat lower mean shell size. The number of cocoons and eggs produced during lifetime by snails kept in pairs was 18-113 and 387-2,862, respectively; the number of eggs per cocoon ranged from 0 to 76. Among singly kept snails only half laid cocoons (maximum 7 cocoons/6 eggs during lifetime), and the eggs failed to develop. The mean life span of snails fed mainly with periphyton was ca. 1 year (maximum 641 days); it was distinctly shorter in snails fed with filamentous diatoms (usually 5-7 months, rarely more than 11 months). In very unfavourable food conditions (small quantities of periphyton) female maturity was attained only after 1-2 years and the life span was not much longer: maximum 830 days. In natural conditions (lake Sosnowe near S¹polno) reproduction started in the second half of April and lasted till half of July; the cocoons contained 10-37 eggs.

Elemental geochemistry of freshwater snail shells: palaeolimnology of a Holsteinian (MIS 11) deposit from eastern Poland

“…), whereas the latter is common in both recent and Pleistocene deposits. Both species secrete aragonitic shells between the late spring and early autumn and are typically buried in the mud during the winter period (Jakubik & Lewandowski ; Myzyk ). The shells of mature V. diluvianus are up to 36 mm tall and 25 mm wide.…”

“…The former is a biostratigraphical indicator and was widely distributed in Europe until the end of the Holsteinian interglacial (Gittenberger et al 2004), whereas the latter is common in both recent and Pleistocene deposits. Both species secrete aragonitic shells between the late spring and early autumn and are typically buried in the mud during the winter period (Jakubik & Lewandowski 2007;Myzyk 2007). The shells of mature V. diluvianus are up to 36 mm tall and 25 mm wide.…”

Across‐shore differences in lake benthic invertebrate communities within reed stands (Phragmites australis (Cav.) Trin. ex Steud.)

“…In accordance with another study, we also found that the outer margins of reed stands were often colonized by taxa preferring pelal substrates (Sychra et al, ), as emergent vegetation supressed water movements and consequently increased sedimentation and the accumulation of mud. Hence, Valvata piscinalis that exhibits an affinity to soft‐bottom sediments and occurs in a broad range of flow conditions, including environments with higher hydrodynamic turbulence (Dillon, ; Grigorovich, Mills, Richards, Breneman, & Ciborowski, ; Mouthon & Daufresne, ; Myzyk, , ), was determined as a species indicative of the outer margin zone in reed stands. In contrast to Sychra et al (), who indicated a high contribution of grazers within reed stands at shore sites, we recorded greater densities of some taxa feeding on algal biofilms at outer margin sites.…”

Life cycle of Anisus vorticulus (Troschel, 1834) (Gastropoda: Pulmonata: Planorbidae) in the laboratory

“…The mean life span for all the snails in the laboratory was 423 days (SD=137, n=39). A more intense feeding caused a slight decrease in the life span, as was the case of snails of the genus Valvata (MYZYK 2002(MYZYK , 2004(MYZYK , 2007. Most laboratory snails wintered once only, only three (hatched in July-August) wintered twice.…”

“…The copulation took place 75 days after hatching, and the first cocoons were deposited three weeks later. In the next year after hatching copulation probably took place only in early spring (end of March -beginning of May), since mating in a later period had no effect on the reproduction, like in Valvata (MYZYK 2002(MYZYK , 2004(MYZYK , 2007. Most of the snails kept in pairs, which reached large shell size before wintering (width more than 5 mm), in the spring deposited cocoons with eggs devoid of oocytes, like the snails kept singly (no copulation?…”