The reproductive cycle of the intertidal gastropod Melarhaphe neritoides on the west and south coasts of Ireland

The reproductive cycle of Melarhaphe neritoides (L.) (Gastropoda, Littorinidae) was studied by histological analysis of the gonads of individuals collected at a range of shore heights at Portnakilly, Clare Island, Co. Mayo, Ireland. For comparative purposes, two additional sites were sampled, but on a less frequent basis: Lekkycranny, Clare Island, Co. Mayo, and Tralispeen, Co. Cork. Staging criteria for the gonads of male and female snails of M. neritoides are described. Oogenesis and spermatogenesis occurred throughout the year at all of the sites, but mature females were found only between September and May at Portnakilly. Shore height did not have an influence on the reproductive cycle. At the exposed site, Lekkycranny, a significantly lower number of mature males were found in the smaller size categories than in the larger categories. Females were more abundant than males on all shores studied, with a significant deviation in the sex ratio at the two Clare Island sites.