HR: 0800h
AN: PP31B-1534    [Abstracts]
TI: Factors Influencing the Stable Oxygen and Hydrogen Isotopic Composition (δ ¹⁸O and δ D) of a Subarctic Freshwater Lake Ecosystem
AU: * Wang, Y
EM: ftyw@uaf.edu
AF: Dept. of Geology and Geophyics, University of Alaska Fairbanks, University of Alaska Fairbanks Duckering 454, Fairbanks, AK 99775 United States
AU: * Wang, Y
EM: ftyw@uaf.edu
AF: Alaska Stable Isotope Facility, University of Alaska Fairbanks, University of Alaska Fairbanks Duckering 437, Fairbanks, AK 99775 United States
AU: Wooller, M J
EM: ffmjw@uaf.edu
AF: Dept. of Geology and Geophyics, University of Alaska Fairbanks, University of Alaska Fairbanks Duckering 454, Fairbanks, AK 99775 United States
AU: Wooller, M J
EM: ffmjw@uaf.edu
AF: Alaska Stable Isotope Facility, University of Alaska Fairbanks, University of Alaska Fairbanks Duckering 437, Fairbanks, AK 99775 United States
AU: Wooller, M J
EM: ffmjw@uaf.edu
AF: School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, School of fisheries and ocean sciences, Fairbanks, AK 99775 United States
AB: Previous studies have shown that the stable oxygen and hydrogen isotopic compositions (δ ¹⁸O and δD) in various animal tissues can be used to examine past climates and animal migration pattern. Little attention has been paid to the relative roles of diet and water influencing the overall δ ¹⁸O and δD of animal tissues in freshwater ecosystems. It is unclear whether different trophic levels in a freshwater lake ecosystem have an identical relationship to the water that surrounds them. The δ¹⁸O and δD values of animal tissues may be controlled by numerous different factors, including metabolic and biosynthetic isotopic fractionation and variations of δ ¹⁸O and δD in the food available. We began to examine these issues by analyzing the δ ¹⁸O and δD throughout a freshwater aquatic ecosystem at Smith Lake in Alaska. We collected samples representing primary producers and consumers (primary and secondary). Samples included green algae, various aquatic plants, such as Nuphar variegatum (water lily), Polygonum amphibium (water smartweed), Carex utriculata (sedge), Utricularia vulgaris (common bladderwort), Typha latifolia (common cattail), and a range of aquatic invertebrates, including Chironomus. sp (midge), Zygoptera (damselfly), Anisoptera (dragonfly), Dytiscidae (diving beetle) and Euhirudinea (leeches). The δ ¹⁸O and δD of Smith Lake water were ~-13.5e and -129.0e, respectively, and we present the δ ¹⁸O and δD of the rest of the ecosystem relative to these data. For instance, the δ ¹⁸O of chironomus sp. was ~12.1‰, which is greater than the of the lake water. Preliminary results suggest the extent of the fractionation between δ ¹⁸O of chironomids vs. lake water δ ¹⁸O is consistent with previous studies. Our data provide an insight into the range of variations that could be expected within a single freshwater ecosystem.
DE: 4942 Limnology (0458, 1845, 4239)
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005