HR: 09:15h
AN: NB31E-04    [Abstracts]
TI: Effects of Variable Flows on Invertebrate Drift in Two Spring Runs in Comal Springs, Texas, USA
AU: * Arsuffi, T
EM: ta04@txstate.edu
AF: Texas Tech University, Field Research Station P.O. Box 186, Junction, TX 76849 United States
AU: Norris, C W
AF: Texas Parks and Wildlife Department, 4200 Smith School Road, Austin, TX 78744 United States
AB: Comal Springs, TX, the largest spring in the western U.S., experiences anthropogenic flow reductions. Drift sampling evaluated the effects of fluctuating flow on quantitative patterns and taxonomic composition of invertebrate drift. The composition, abundance, and seasonal patterns of drift varied between runs. Invertebrate drift was greater (2x) at night than by day and marked crepuscular peaks in drift activity, common in streams throughout the world, were observed in only one spring run. Multiple regression analysis of the total drift rate and drift density in each spring run was performed with water depth, current velocity, and Julian day as independent variables. Significant relationships were found in spring run 1, but not in spring run 3. Simple linear correlations between drift of individual taxa in each spring run and the three independent variables showed significant negative relationships to current velocity and water depth, while drift rate and density of several taxa in spring run 3 showed significant positive relationships to current velocity. This indicates differences in habitat and organism ecology between the spring runs may cause different responses to variable flows. Such insects may be used as indicators of hydrological change and used to predict critical flow levels and aquifer management targets.
DE: 1803 Anthropogenic effects
DE: 1812 Drought
DE: 1845 Limnology
DE: 1899 General or miscellaneous
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly