Wednesday, May 28, 2008 - 9:45 AM
381

Effects of channelization on macroinvertebrate communities in a semi-arid riverscape

Thomas L. Kennedy and Thomas F. Turner. Biology, University of New Mexico, MSC 03 2020, 1 University of New Mexico, Albuquerque, NM 87131

Large river ecosystems usually are flanked by lowland riparian areas that are purported to harbor much aquatic species diversity.  River regulation and channelization have, in many places, isolated previously connected rivers from surrounding riparian areas. We examined monthly aquatic and riparian survey data of macroinvertebrates from the Rio Grande, NM to determine the effects of channelization on the macroinvertebrate community. Macroinvertebrates were surveyed in 2006 and 2007 at four locations: two channelised reaches and two semi-natural, non-channelised reaches. Results from the survey data indicate no statistically significant differences in the taxonomic richness and Simpson’s Diversity Indices between channelised and non-channelised reaches. However, average densities and abundances of aquatic and riparian macroinvertebrates were lower in the channelised reaches. Taxonomic richness and Simpson’s Diversity of riparian macroinvertebrates were lower in channelised reaches with riparian predator richness and abundance showing the largest decline. These results indicate that channelization can reduce macroinvertebrate densities and negatively impact diversity at the landscape scale by severing the linkages between the aquatic and riparian communities.  These effects appear especially acute for macroinvertebrates in higher trophic levels, perhaps because preferred prey density is lowered.


Web Page: Channelization, diversity, macroinvertebrates

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