HR: 09:30h
AN: B51A-05    [Abstracts]
TI: The Influence of Flood Disturbances on Interspecific Competition Between Stream Invertebrates
AU: * Effenberger, M
EM: effenberger@zi.biologie.uni-muenchen.de
AF: Department Biology, Aquatic Ecology, University of Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
AU: Diehl, S
EM: diehl@zi.biologie.uni-muenchen.de
AF: Department Biology, Aquatic Ecology, University of Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany
AU: Matthaei, C D
EM: christoph.matthaei@stonebow.otago.ac.nz
AF: Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand
AB: We investigated the influence of repeated abiotic disturbances on interspecific competition between stream invertebrates. Artificial substrates (tiles) were exposed in 2 German streams with different flow regimes (floodprone versus stable). Half the tiles were disturbed (once every 2 weeks) by scrubbing to simulate a bed-moving flood, the other half remained undisturbed. We also manipulated densities of 2 of the most common invertebrate taxa in each stream (floodprone: Baetis and Heptageniidae; stable: Simulium and Brachycentrus montanus). Three invertebrate removal treatments (removal of taxon 1, removal of taxon 2, and unmanipulated controls) were applied, and invertebrates were removed every 3 days. After 2, 4 and 6 weeks each, we sampled 8 tiles from each treatment and determined invertebrate faunal composition, epilithic algal biomass (Chl a) and biofilm biomass (AFDM) for each sample. Both disturbance and invertebrate removal affected the stream biota. Disturbance reduced algal and biofilm biomasses in both streams, and invertebrate density in the floodprone stream. Brachycentrus removal resulted in higher flatworm density. Disturbance and invertebrate removal also interacted with each other. Density of the "non-target" mayfly Baetis in the stable stream was highest in Simulium removal treatments on disturbed tiles, but lowest in Simulium removal treatments on undisturbed tiles.
DE: 1815 Erosion and sedimentation
DE: 1821 Floods
SC: Biogeosciences [B]
MN: 2005 Joint Assembly