SHORT-TERM RECOVERY OF BENTHOS FOLLOWING DISTURBANCE FROM STREAM HABITAT REHABILITATION

The recovery of benthic macroinvertebrates after disturbance from stre am rehabilitation was studied in the River Livojoki, northern Finland. The stream that had been channelized for log transport was rehabilita ted on 1 July 1992 by digging holes and inserting boulders. We measure d habitat characteristics and sampled benthic animals before and after rehabilitation, including an unrehabilitated control site. The immedi ate effect of rehabilitation was a slight decrease in the abundances o f benthic insects. Recolonization occurred rapidly, within 10 days. Di sturbance of the rehabilitation did not have a detectable effect on th e macroinvertebrate community. Most species-level changes and communit y patterns reflected seasonal life history events. Timing of such reha bilitation work can be critical for the recovery rate, which depends o n the colonization abilities of the species present after disturbance. We suggest that many disturbances (including minor floods and moderat e rehabilitation procedures) may have only small, short-term effects o n benthic communities. We emphasize the importance of considering seas onality in studies of disturbance in streams.