The aim of this study is to describe the main types of water bodies in the lower Hron River (Slovakia) using Mollusca as ���functional describers��� of the ecosystem dynamics. In European context, the Hron River belongs with its average discharge 53.7 m3.s���1 to small rivers; course length is 297 km. Major part of the alluvial plain exhibits strong human impact, though there are still relics of relatively well-preserved main successional stages of water bodies. The sampling (set-time period method) was stratified on the distribution of aquatic macrophytes (if presented). A total of 35 species was found alive (23 gastropods, 12 bivalves). The most constant species were Radix auricularia and Galba truncatula. In eupotamon, 13 species were found; characteristic species were Valvata piscinalis, Gyraulus albus, Unio pictorum, U. tumidus, Pisidium spp., Ancylus fluviatilis, and Radix peregra. In parapotamon, the bivalve Sphaerium corneum was a characteristic species, plesiopotamon had no characteristic species; for paleopotamon were characteristic Planorbis planorbis and Aplexa hypnorum, also a non-indigenous snail Physella acuta was constant. In anthropogenic water bodies no differentiative species were presented; the presence and dominance of Physella acuta is typical.