Tuesday, June 5, 2007
473

Snag-Dwelling Invertebrates of the Rio Grande: Recovery After a Long-Term Desiccation Disturbance

Benjamin J. Weibell, Department of Biology, Anne Arundel Community College, 238 DRGN, 101 College Pkwy, Arnold, MD 21012 and Arthur C. Benke, Department of Biological Sciences, The University of Alabama, Box 870206, Tuscaloosa, AL 35487.

Wood is an important invertebrate habitat in river ecosystems, but most quantitative information about wood-dwelling invertebrates is from Coastal Plain rivers of the southeastern U.S.  Little work has been done in other types of rivers such as Basin and Range rivers of the southwestern USA.  We conducted a preliminary study of wood-dwelling invertebrates in the Rio Grande, NM, and followed recovery after human-induced desiccation.  Abundance ranged from 2,170 – 67,964 individuals/m2 of wood surface, while biomass was 199 – 9,823 mg/m2.  Diptera (12,524 individuals/m2), Ephemeroptera (5,792 individuals/m2), and Trichoptera (5,165 individuals/m2) dominated the community.  Abundance and biomass in the Rio Grande were not significantly different than values from a Coastal Plain river in Alabama.  Taxonomic composition was similar to invertebrates in Coastal Plain rivers, but wood-burrowing caddisflies were absent and only one elmid (Coleoptera) species was present.  Abundance in the desiccated reach recovered quickly (2 weeks), but taxonomic composition did not.  DCA indicated the invertebrate community in the recovery area was unique compared with reaches that remained inundated.  Despite low wood quantity in the Rio Grande, wood still attracted a high diversity and biomass of invertebrates suggesting it might be a critical habitat in this system.

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