HR: 16:30h
AN: NB44D-05    [Abstracts]
TI: Complex Interactions Among Detritivorous Insects Inhabiting Leaf Packs in a North Carolina Stream
AU: * Pflaum, J R
EM: jp51668@appstate.edu
AF: Appalachian State University, Dept. of Biology 572 Rivers Street, Boone, NC 28608 United States
AB: Large detritivorous insects may influence the distribution and abundance of other invertebrates that inhabit leaf packs. In a previous study we observed a complementary distribution between the caddisfly Pycnopsyche and ephemerellid and leptophlebiid mayflies in a headwater stream. Initially, we hypothesized that encounter competition between these organisms was the mechanism responsible for this distribution. When presented with a choice of leaf packs in an enclosure, one of which contained Pycnopsyche, neither ephemerellids nor leptophebiids exhibited significant avoidance of leaf packs inhabited by Pycnopsyche. However, a significant number of mayflies from both families were not recovered suggesting that intraguild predation was occurring. A preliminary stable isotope analysis does not support the intraguild predation hypothesis. In a field experiment we examined invertebrate colonization of leaf packs on which we placed 0, 3, and 6 Pycnopsyche. We hypothesized that leaf packs with no Pycnopsyche would have higher numbers of colonizing invertebrates (particularly mayflies) than leaf packs with Pycnopsyche. Results of this study showed that some taxa increased in the presence of Pycnopsyche while other taxa declined. Our results suggest that Pycnopsyche may influence the distribution and abundance of other invertebrate taxa through various mechanisms.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly