Monday, May 26, 2008 - 9:45 AM
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Kootenai River nutrient experiment (3rd Yr.): Using an ecosystem approach to rehabilitate fisheries in a 6TH order regulated river in northern Idaho, USA

Charles E. Holderman1, Gary T. Lester2, Genevieve Hoyle1, and Ryan Hardy3. (1) Fish and Wildlife, Kootenai Tribe of Idaho, POBox 1269, County Rd 38A, Mission Hill, Bonners Ferry, ID 83805, (2) CEO, President, EcoAnalysts, Inc., 1420 South Blaine Street, Suite 14, Moscow, ID 83843, (3) Fisheries, Idaho Department of Fish and Game, 2750 Kathleen Ave, Coeur d’ Alene, ID 83814

The Kootenai River aquatic ecosystem has been significantly degraded due to wetland loss and impoundment during the last century. Important fish stocks have accordingly declined, especially after the completion of Libby Dam, a major hydroelectric facility in 1974. Starting in 2002,  annual multi-trophic level and nutrient concentration monitoring was initiated to determine if bottom-up nutrient limitation is detrimentally affecting the ecosystem. Based on findings of low nutrient levels, chlorophyll a, macroinvertebrate biomass and fish condition factors, river managers initiated a large-scale nutrient addition experiment in the regulated reach of the Kootenai River. Since 2005, controlled amounts of phosphorus (10-34-0) have been added to the river during the summer growing season targeting a concentration of 1.5 µg l-1 in 2005 and 3.0 µg l-1 TDP in 2006 and 2007. Initial responses in chlorophyll a, macroinvertebrate abundance and biomass, and fish density have been positive and will be presented.


Web Page: Nutrients, Experiment, Fisheries