HR: 15:45h
AN: H44A-02    [Abstracts]
TI: Examining the Utility of Stable Hydrogen Isotopes in Aquatic Food-Web Ecology
AU: * Doucett, R R
EM: Richard.Doucett@nau.edu
AF: Northern Arizona University, Department of Biological Sciences, Building 21, South Beaver Street, Flagstaff, AZ 86011-5640 United States
AU: Blinn, D W
AF: Northern Arizona University, Department of Biological Sciences, Building 21, South Beaver Street, Flagstaff, AZ 86011-5640 United States
AU: Caron, M
AF: Northern Arizona University, Department of Biological Sciences, Building 21, South Beaver Street, Flagstaff, AZ 86011-5640 United States
AU: Ellis, B K
AF: Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT 59860-9659 United States
AU: Marks, J C
AF: Northern Arizona University, Department of Biological Sciences, Building 21, South Beaver Street, Flagstaff, AZ 86011-5640 United States
AU: Hungate, B A
AF: Northern Arizona University, Department of Biological Sciences, Building 21, South Beaver Street, Flagstaff, AZ 86011-5640 United States
AB: The utility of stable hydrogen isotopes (dD) in hydrology and terrestrial ecology is well understood, but it has not been sufficiently examined in the field of aquatic ecology. Here, we present initial results from: (1) the Colorado River (AZ), Fossil Creek (AZ) and Devil's Hole (NV), where we examined the usefulness of dD to distinguish between allochthonous and autochthonous inputs to aquatic food webs, and (2) from the Sopochnaya River, Russia, where we tested the ability of dD to discern between anadromous and freshwater steelhead trout. In general, aquatic inputs (-320 to -168 per mil) were much more depleted than terrestrial inputs (-166 to -105 per mil). Macroinvertebrates displayed dD values similar to presumed food sources (e.g., baetid mayflies ranged from -299 to -222 per mil). In some cases, mixing models suggested that dD was a better predictor of food-source origin than d13C. As expected, dD values for anadromous trout (-121 to -103 per mil) were more enriched than those of freshwater residents (-161 to -123 per mil), and strong correlations existed between dD, d34S, and d13C. Methodological considerations (e.g., exchangeable hydrogen) and certain assumptions (e.g., importance of food vs. water on tissue dD) will be discussed.
DE: 1030 Geochemical cycles (0330)
DE: 1040 Isotopic composition/chemistry
DE: 1845 Limnology
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2005 Joint Assembly