Wednesday, June 6, 2007 - 4:00 PM
328

The Hyporheic Invertebrates of a Southern Arizona Stream

Christine L. Goforth, Department of Entomology, University of Arizona, 1140 E South Campus Drive, Tucson, AZ 85721 and David Walker, Environmental Research Laboratory, University of Arizona, 2601 E Airport Drive, Tucson, AZ 85706.

The hyporheic zone of streams often contributes valuable habitable space that may be utilized by aquatic invertebrates.  It provides a permanent home for some organisms and acts as a refugium during periods of stream drying for others.  Most studies of the hyporheos have been conducted in permanent streams of mesic regions, but the hyporheic communities of arid region streams are poorly studied.  To determine the invertebrate community of the hyporheic zone in an arid region ephemeral stream, we sampled the hyporheos of Rincon Creek in southern Arizona for two years.  We placed four colonization samplers in the streambed at each of three sites, then removed the contents of two samplers per site monthly and two quarterly.  The contents were preserved and all aquatic invertebrates were removed, counted, and identified to genus.  The hyporheic zone of Rincon Creek contained very few invertebrates, likely due to severe hypoxia and poor substrate, and was apparently of little value to the invertebrates of the stream.  It is possible that the hyporheic zones of arid region streams iares generally unproductive compared to mesic region streams.  Additional streams in arid regions should be studied to determine whether this is the case.