AbstractThe harpacticoid copepodLimnocamptus echinatus(Mrazek) shows a very distinct large‐scale vertical distribution within the bed sediments of Oberer Seebach, a second‐order gravel stream. The population peak appears in a sediment layer between 15 and 35 cm over long periods on average. Abundances are significantly lower in the topmost sediments and sediment layers below 50 cm depth. The large‐scale vertical distribution is mainly influenced by the changes and pattern of temperature and discharge, which influences the current velocity of the surface and interstitial water. Effects appear quite different, when permanent flooded areas and areas that periodically fall dry on the surface are compared.Limnocamptus echinatusis forced deeper into the sediments of the gravel bar during low water temperatures and/or high discharge situations. On permanent flooded areas the vertical distribution is more stable over long periods, but higher fluctuations occur during short periods. TheLimnocamptus echinatuspopulation shows higher mobility in deeper sediment layers (40 to 60 cm sediment depth). Comparing longer periods, water flow and the transport of fine material differ in deeper sediment layers. The water current is much slower, producing a tendency for fine material sedimentation. This might be the main reason for the higher mobility in deeper sediment layers and the restriction of 90 per cent of theLimnocamptus echinatuspopulation to a sediment depth of 50 cm. High mobility in vertical and horizontal directions within the bed sediments is interpreted as normal reactions and adaptations to the dynamic behaviour of the system, mainly forced by physical parameters. Biological parameters appear as subdominant for large‐scale vertical distri