HR: 14:30h
AN: NB23B-05    [Abstracts]
TI: Do Droughts Have Similar Consequences for Benthic Macroinvertebrate Communities in Similar Streams?
AU: * Brown, B L
EM: stonefly@mail.utexas.edu
AF: University of Texas at Austin, 1 University Station C0930 University of Texas at Austin, Austin, TX 78712 United States
AB: Hydrologic variability due to drying is common in streams, but does a single drought disturbance have similar effects across streams? In 2002, a severe drought occurred during an experiment designed to test the influence of habitat heterogeneity on macroinvertebrate community stability in two New Hampshire streams. I used this "demonic intrusion" to compare the effects of a single drought disturbance on benthic community composition in two similar streams. Prior to the drought, Alder and Loomis Valley Brooks, were very similar in size, discharge, cover, substratum, and community composition. However, following the drought, both univariate and multivariate measures of community composition demonstrated dramatic differences between the two streams with Loomis Valley shifted towards a community dominated by collector/gathering taxa, and Alder Brook dominated by predators, shredding detritivores, grazers, and filter feeders. In both streams, habitat heterogeneity played little or no role in mediating drought effects. Many of the post-drought differences between streams may have resulted from differential hydrologic impacts of the drought: Loomis Valley was without visible surface flow for several weeks, while Alder had reduced but visible surface flow. These results demonstrate that drought effects on benthic macroinvertebrate communities must be considered in a context which incorporates local hydrologic conditions.
DE: 1800 HYDROLOGY
DE: 1812 Drought
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly