Invertebrate recolonization patterns in the hyporheic zone of a gravel stream

Invertebrate recolonization at short-term exposures (2-192 h) in the hyporheic zone of a gravel stream revealed significant depth-specific differences. In the shallow hyporheic zone (0-20 cm), mean meiofaunal density increased asymptotically stabilizing within 66 h, a similar but nonsignificant pattern was found for macrofauna. Permanent meiofaunal members (e.g., rotifers, chironomids, cyclopoids) were the fastest colonizers of the traps. At the deeper hyporheos (20-50 cm) meiofauna and macrofauna entered the pipes rapidly (2 h) but neither a power curve nor an asymptotic curve described their colonization pattern. Nonlinear regression analysis indicated a significant relationship between amounts of interstitial sediment entering the pipes and abundances of macrofauna and meiofauna.