The effects of forestry activities on macroinvertebrate community structure were examined in the
headwaters of Carey Brook in the south-west of Australia. The fauna at four sites on an upland
stream that ran through a logging coupe were compared, before and after clearfelling, with the
fauna at four nearby undisturbed sites. Mean species richness and mean total abundance declined
at the treatment sites relative to the control sites after the commencement of clearfelling activities.
The composition of the macroinvertebrate fauna in the disturbed stream changed in comparison
with that in the undisturbed sites after logging started but returned to the pre-logging composition
after winter and spring rains had stopped. The observed changes in the macroinvertebrate fauna
occurred during the periods of high loads of suspended inorganic solids at the treatment sites.
The possible reasons for the observed results are discussed.