Patterns of egg laying by the tidal salt marsh snail,Melampus bidentatus(Say), in relation to lunar phase

Abstract

Summary Tidal marsh snails, Melampus bidentatus, from the Barn Island marsh in Stonington, Connecticut, showed a lunar (4-week) periodicity to egg laying during the 1992 reproductive season but a semilunar (2-week) egg-laying rhythm in 1993. These different egg-laying patterns were observed under laboratory conditions that were identical during the 2 years, as well as in the field. This fact suggests that environmental conditions existing prior to the reproductive season may be important in regulating the egg-laying periodicity. During the 1993 season, snails from four other southern New England marshes also exhibited a semilunar egg-laying rhythm; however, variations on this pattern were observed. Data accumulated during this study are consistent with the hypothesis that fecundity of M. bidentatus is size specific.