The Natural History of an Ovoviviparous Snail, Viviparus georgianus (Lea), in a Soft-Water Eutrophic Lake

Abstract

A population of the freshwater viviparid prosobranch snail, Viviparus georgianus, was studied in an eutrophic lake in western Connecticut. Male and female life spans were two and three years, respectively. Females grew longer and relatively wider than males. Shell growth of width to height was allometric and similar in pattern to another viviparid, Cipangopaludina chinensis. Growth rates were rapid after the lake warmed in spring and were negligible during winter. Mortality was relatively low for younger snails, and the death of the eldest cohort was a highly synchronized event occurring in late spring. Reproduction was semelparous. Females brooded a single batch of eggs for nine months during their third year (27-36 months old), released the young in April, and died at 38 months of age. The population demonstrated a migratory pattern which resulted in deep water winter aggregations and shallow water summer aggregations. Older males and females migrated together but the youngest cohort tended to lag behind.