HR: 16:00h
AN: NB14A-03    [Abstracts]
TI: Effect of ¹⁵ N Labeled Riparian Fertilization And Salmon Carcass Analog Addition On Food Web Dynamics And Productivity In Four Idaho Streams
AU: * Rugenski, A T
EM: arugenski@yahoo.com
AF: Idaho State University, Department of Biological Sciences, Pocatello, ID 83209 United States
AU: Kohler, A
EM: akohler@shoshonebanncoktribes
AF: Shoshone-Bannock Tribes, Fisheries and Wildlife Department, Fort Hall, ID 83203 United States
AU: Minshall, G W
EM:
AF: Idaho State University, Department of Biological Sciences, Pocatello, ID 83209 United States
AU: Danehy, R J
EM:
AF: Weyherhaeuser Corporation, Fisheries and Wildlife Department, Eugene, OR United States
AU: Taki, D
EM:
AF: Shoshone-Bannock Tribes, Fisheries and Wildlife Department, Fort Hall, ID 83203 United States
AB: Nutrient budgets of stream/riparian ecosystems in the Intermountain West have been depleted through declining salmon populations and certain anthropogenic disturbances (e.g. forestry practices). We measured stream food web responses to a riparian fertilization and an in-stream carcass analog addition in 4 Idaho streams with a ¹⁵ N tracer. Aerial application of fertilizer pellets to light (224 kg/ha) and heavy (448 kg/ha) treatment sections of 2 streams and carcass analog additions to 2 others were completed in autumn. Periphyton response was measured through chlorophyll a, nutrient diffusing substrata, and stable isotope analyses. Macroinvertebrates were analyzed for abundance, biomass, community structure, and stable isotope composition. Also, willow (Salix) breakdown rates were determined. Pre-treatment chlorophyll a values showed no significant difference between treatment and reference reaches. Post-treatment results showed significantly higher chlorophyll a and δ ¹⁵ N values in treatment reaches compared to reference reaches. Macroinvertebrate abundance, richness, biomass, and δ ¹⁵ N values also increased in treated reaches. No significant differences were detected in leaf breakdown rates between reaches. Riparian fertilization effects were longer lasting than the in-stream treatment. These results suggest that nutrient addition to streams and riparian areas can be used as a management tool to increase stream productivity where nutrients are limiting.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly