Adult-larval interactions in the suspension-feeding bivalves Cerastoderma edule and Mya arenaria

The influence of adult density on settlement and recruitment in the suspension-feeding bivalves Cerastoderrna edule (L.) and Mya arenaria L. was investigated in a shallow soft-sediment area on the west coast of Sweden.Quantitative sampling for juvenile bivalves was performed in areas with varying densities of adult C. edule.Densities of adult C. edule and M. arenaria were also manipulated in experimental field plots.In the field study there was a negative relationshp between adult density and newly settled bivalve larvae.Four months after peak settlement the density of juvenile bivalves was still 4 times higher in the area with few adult C. edule.In the field experiment, adult C. edule and M. arenaria reduced the settlement of bivalve larvae by up to 40 and 20 % respectively.The significant effect of adult density was, however, leveled out shortly after settlement.We conclude that adult benthic suspension feeders significantly reduce settlement success of bivalve larvae, and hence may limit recruitment of new individuals.