Effects of Selective Taxa Removal on Lotic Macroinvertebrate Colonization in a Wooded Piedmont USA Stream

Abstract

Abstract The assemblage composition, following selective taxa removal, was examined on already colonized rocks in a North Carolina, piedmont stream. The taxa removed were either the net-spinning caddisfly Cheu-matopsyche sp. or the case-building chironomid Rheotanytarsus sp.. Handled rocks with no removals were the controls. Since both taxa were numerically dominant at the start of this study but occuppied different amounts of rock space, we hypothesized that the colonization dynamics following the removals would be different between the two treatments. Over the 14 day study period, no differences in total number of individuals (N), or number of taxa (S) were detected among treatments. High within-treatment variablity in these factors contributed to this result. The only taxa which showed a treatment effect (apart from the removal itself) were the chironomids Corynoneura sp., and Paraphaenocladius sp.. Both taxa were more abundant on rocks with Rheotanytarsus removed than on controls, suggesting competiti...