Tuesday, May 27, 2008
315

Invertebrate diversity is linked to detritus quantity in a southern Appalachian headwater stream

Sue L. Eggert, Northern Research Station and Dept. of Entomology, USDA Forest Service and University of Georgia, Grand Rapids, MN 55744, J. Bruce Wallace, Dept. of Entomology and Odum School of Ecology, University of Georgia, Athens, GA 30602, Judy L. Meyer, Odum School of Ecology, University of Georgia, Athens, GA 30602, and Jackson R. Webster, Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.

An experimental manipulation of organic matter (litter exclusion, wood removal, and leaf addition) in an Appalachian headwater stream resulted in significant declines and increases in productivity following litter exclusion and leaf litter addition.  We predicted that invertebrate diversity, as defined as the number of taxa reaching mature size classes, would also change with quantity and quality of detrital resources and would be related to productivity.  Analysis of size frequency distributions and maximum sizes of representative taxa over the 14-year period showed greater changes in maximum size for those taxa that were more dependent on CPOM resources (Pycnopsyche, Lepidostoma, Leuctra) than those that were not (Diplectrona).  Many taxa, including some predators (Beloneuria), did not survive to emergence when detrital resources were reduced or eliminated.  The addition of leaves of various qualities (fast, slow, and intermediate breakdown rates) to the treatment stream resulted in normal size distributions for most taxa.  Sufficient quantities of fast breakdown leaf species remained in the treatment stream long enough to allow survival until emergence and likely reproductive success.  Our results show that the reduction of detrital resources had a greater effect on invertebrate diversity and productivity than leaf quality.


Web Page: detritus, invertebrate, diversity

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