Comparative fecundity in three Danish Mudsnails (Hydrobiidae)

Abstract

Abstract The reproduction of three species of mud snails, Hydrobia neglecta, H. ulvae and H. ventrosa is studied under constant conditions of various temperature/salinity combinations and in seven field populations. Under otherwise constant conditions the egg production of H. neglecta increases with temperature (4-24°C), while it decreases in H. ulvae and H. ventrosa. All species show a general peak in reproductive activity around 20 ‰ salinity. In H. neglecta egg production is retarded at low salinity, which may explain the absence of the species in the inner Baltic Sea. All natural populations exhibit peak reproductive activity during May-June, and total numbers of eggs compare well with the values obtained under constant conditions.