HR: 0800h
AN: B41D-0219    [Abstracts]
TI: Stable Isotope Investigation of Marine-Terrestrial Nitrogen Linkages in Salmon Stream Ecosystems
AU: * Sayer, A M
EM: asams58@uaa.alaska.edu
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AU: Welker, J M
EM: afjmw1@uaa.alaska.edu
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AU: Rogers, M
EM: mcrogers78@hotmail.com
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AU: Rinella, D J
EM: andjr@uaa.alaska.edu
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AU: Sveinbjornsson, B
EM: afbs@uaa.alaska.edu
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AU: Wipfli, M
EM: mark.wipfli@uaf.edu
AF: University of Alaska, 3211 Providence Drive, Anchorage, AK 99507 United States
AB: Our research is addressing marine-terrestrial nitrogen linkages using stable isotope techniques (δ15N). Throughout coastal Alaska, salmon migrate each year into riparian systems transporting marine-produced biomass (carbon, phosphorous and nitrogen) that is decomposed, recycled and used by juvenile fish, invertebrates, carnivores and in some cases aquatic and terrestrial vegetation. These inputs of N into the terrestrial landscape have a host of cascading implications including the maintenance of biodiversity, enhanced survivorship of juvenile salmon and support of a complex food web that includes primary and secondary consumers (bears and eagles) and herbivores such as moose. A central question regarding this marine-terrestrial linkage is whether vegetation (aquatic or terrestrial) uses marine-derived N in metabolism and whether this fertilization effect increases leaf N contents, leads to higher rates of plant growth, results in higher rates of leaf gas exchange, and increases forage quantity and quality. By analyzing the δ15N-values of plants we will be able to fingerprint marine N use by plants and the degree to which this N contributes to the nitrogen budget of riparian vegetation.We are quantifying marine N use by aquatic and terrestrial vegetation (trees, shrubs and grasses) within the Kenai River watershed using a comparative approach sampling streams with annual salmon runs and streams without runs (waterfall inhibiting salmon spawning). We will determine the relationship between local hydrology and marine nutrient access using a multi-isotope approach which examines the relationship between plant water sources and relations and marine N use. We will ascertain the ecological importance of this N source by comparing the growth and ecophysiology of riparian vegetation along salmon impacted and non impacted streams. Initial results indicate that riparian vegetation along streams with large salmon runs have higher leaf N contents and enriched δ15N values compared to low salmon run streams and that differences in plant growth is life form specific.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0476 Plant ecology (1851)
DE: 0483 Riparian systems (0744, 1856)
SC: Biogeosciences [B]
MN: Fall Meeting 2005