Aquatic Sciences Meeting, Albuquerque 2001

SS10 Human Activities and Their Effects on Aquatic Ecosystems (Environmental Connections; Science and Society Connections)

Date: Monday, February 12, 2001, Time: 3:00:00 PM

Location: La Cienega

Edwards, M, S, University of New Mexico, Albuquerque, USA, medwards@unm.edu

Turner, T, F, University of New Mexico, Albuquerque, USA, turnert@unm.edu

Sharp, Z, , University of New Mexico, Albuquerque, USA, zsharp@unm.edu

QUANTIFYING CHANGES IN FOOD WEBS OVER TIME USING STABLE ISOTOPE ANALYSES OF MUSEUM SPECIMENS

The Rio Grande has been severely altered by river regulation facilities that may have affected the river food web. Stable isotopes have been used as tracers for, and quantification of, changes in food webs; studies often compare a separate reference system, which is assumed to be the same as the pre-disturbance system, to the altered system. The assumption above may not always hold true. Additionally, in many circumstances an undisturbed reference system does not exist, as is the case in the Rio Grande. We are using museum-preserved specimens (pre-disturbance) to compare with recently collected specimens (post-disturbance), from the same system, for stable isotope analysis. Though formalin preservation is known to change the stable isotope content of preserved tissues, our studies demonstrate that the differences in the stable isotope content between fresh and preserved tissues for nitrogen, carbon, and sulfur are minimal and predictable. Several factors were investigated as potential causes for the shift in the delta values for preserved tissue (lipid extraction by formalin, differences in formalins, time in formalin, and others) in an effort to develop a correction factor.

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Aquatic Sciences Meeting, Albuquerque 2001

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