Longitudinal variation in abundance of a freshwater pearl mussel Margaritifera margaritifera population in relation to riverine habitats

Abstract

A census of the population of freshwater pearl mussel Margaritifera margaritifera in a 1.6-kin stretch of lowland river in south-west Ireland was taken as part of an environmental impact study for a proposed flood relief scheme. Ninety-four cross-sections (2-3m wide) were taken and various habitat parameters were recorded. The total population was estimated to be 14,194 and four juveniles were recorded. High mussel densities were associated with shaded channels and low channel depths.