The Distribution of Hydrobiids and the Effects of Sediment Characteristics on the Population Dynamics of Hydrobia ventrosa in a Coastal Region of the Southern Baltic

Abstract

AbstractThe composition of the hydrobiid fauna in a coastal water of the southern Baltic was studied in 1990/91 at three stations with different sediment characteristics (grain size, organic content). Four species were found (Hydrobia ventrosa, H. ulvae, H. neglecta and Potamopyrgus jenkinsi). H. ventrosa was dominant at all stations. The mean hydrobiid abundances were 4,000 (stn. C), 18,000 (stn. B) and 40,000 (stn. A) ind./m2 respectively. Abundance was found to correlate with the organic content of the sediment. The reproduction and growth of H. ventrosa was studied. Two reproduction phases were observed, one in summer and the other in late autumn. The autumn reproduction peaks were staggered owing to the different growth rates at the various stations. Possible correlations between the differences in shell size of H. ventrosa at the various stations and both sediment characteristics and abundance are discussed.