Effects of flow regulation on disturbance frequencies and in-channel bryophytes and macroalgae in some upland streams

Abstract

River regulation can cause various downstream changes to the physical environment of stream channels. Here, we examined whether disturbance of the stream bed and/or degree of emergence of large substrata affect the diversity and abundances of bryophytes and macroalgae in three regulated and three unregulated upland streams. We marked and mapped randomly selected rocks in situ for each stream and measured the rates at which these substrata disappeared. We recorded percentage covers of bryophytes and macroalgae in each stream on rocks of differing sizes ('small' 20 cm maximum top dimension) and lying either loosely on top of the bed or packed into it; we also recorded when rocks were emergent...