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

1985; Taylor & Francis; Volume: 3; Issue: 2 Linguagem: Inglês

10.1080/02705060.1985.9665109

2156-6941

Jerome M. Diamond, Seth R. Reice,

Aquatic Ecosystems and Phytoplankton Dynamics

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 competitive interaction among these chironomid taxa. No differences in assemblage composition were detected between the two removal treatments. On the contrary, all treatments underwent a similar change in assemblage composition over time. Neophylax (Trichoptera) and Psephenus herricki (Coleoptera) became more abundant and the mayflies Stenonema modestum and Baetis sp. less abundant, due either to differences in their seasonal life history patterns or interspecific competition. Colonization patterns appeared to be stochastic in this system, but the outcome of colonization was statistically predictable. Abiotic factors and seasonal processes appear to be more important than biotic interactions in explaining convergence in lotic assemblage composition over time in this system.