Tuesday, May 27, 2008
331

Length-mass relationships for freshwater macroinvertebrates of the middle rio grande, New Mexico

Monica K. Tellez, Ayesha S. Burdett, and Thomas F. Turner. Department of Biology and Museum of Southwestern Biology, University of New Mexico, MSC 03-2020, 1 University of New Mexico, Albuquerque, NM 87131

Biomass measurements are important for answering questions about trophic dynamics in aquatic systems. Measuring dry weight for biomass is a destructive process, but specimens may be needed for other processes (e.g. stable isotope analysis) or for long-term preservation. Length-mass regression is a non-destructive process that is widely used for calculation of biomass. However, length-mass regressions have not been calculated for some macroinvertebrates common to the Middle Rio Grande, NM.  Macroinvertebrates were collected from The Bosque Del Apache National Wildlife Refuge in summer 2007.  Abundant taxa were measured and sorted into classes by total body length and head width, then oven-dried and weighed. We performed regression analyses on Corisella (Corixidae) for both adults and nymphs.  Head width and body length both provide fairly strong estimates for biomass for both adults and nymphs (R2 = 0.75 - 0.90). Head width measurements may be useful for damaged individuals where the total body length cannot be measured. Other taxa to be included in regression analyses are mayflies (Callibaetis, Tricorythodes), snails (Physa) and beetle larvae (Dytiscidae, Staphylinidae). These regressions will be useful for estimating macroinvertebrate biomass and turnover in the Rio Grande system.


Web Page: Biomass, Rio Grande, Regression

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