Characterization of the Kootenai River aquatic macroinvertebrate community before and after experimental nutrient addition, 2003–2006

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The Kootenai River ecosystem has experienced numerous ecological changes since the early 1900s. Some of the largest impacts to habitat, biological communities, and ecological function resulted from levee construction along the 120 km of river upstream from Kootenay Lake, completed by the 1950s, and the construction and operation of Libby Dam, completed in 1972 on the river near Libby Montana. Levee construction isolated tens of thousands of hectares of historic functioning floodplain habitat from the river channel, eliminating nutrient production and habitat diversity crucial to the functioning of a large river-floodplain ecosystem. Libby Dam continues to create large changes in the timing, duration, and magnitude of river flows, and greatly reduces sediment and nutrient transport to downstream river reaches. These changes have contributed to the ecological collapse of the post-development Kootenai River ecosystem and its native biological communities. In response to this artificial loss of nutrients, experimental nutrient addition was initiated in the Kootenay Lake’s North Arm in 1992, the South Arm in 2004, and in the Kootenai River at the Idaho-Montana border during 2005. This report characterizes the macroinvertebrate community in the Kootenai River and its response to experimental nutrient addition during 2005 and 2006. This report also provides an initial evaluation of cascading trophic interactions in response to nutrient addition. Macroinvertebrates were sampled at 12 sites along a 325-km section of the Kootenai River, representing an upriver unimpounded reference reach, treatment and control canyon reach sites, and braided and meandering reach sites, all downstream from Libby Dam. Principle component analysis revealed that richness explained the greatest amount of variability in response to nutrient addition as did taxa from Acari, Coleoptera, Ephemeroptera, Plecoptera, and Trichoptera. Analysis of variance revealed that nutrient addition had a significant effect (p<0.0001) on invertebrate abundance, biomass, and richness at sites KR-9 and KR-9.1 combined (the zone of maximum biological response). Richness, a valuable ecological metric, increased more than abundance and biomass, which were subject to greater sampling bias. Cascading trophic interactions were observed as increased algal accrual, increased in-river invertebrate abundance, and increased invertebrate counts in mountain whitefish (Prosopium williamsonii) gut samples, but were not quantitatively tested. Sampling and analyses across trophic levels are currently ongoing and are expected to better characterize ecological responses to experimental nutrient addition in the Kootenai River.

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ELECTRONIC FILE - Zoology: Invertebrate

Prepared for: Kootenai Tribe of Idaho, Bonners Ferry, ID
Document no.: P110393 [I wasn't able to determine the full name of, or find, the document that this "chapter" was a part of, so might not have the name (or even type of document) correct and do not have the larger work's author/editor names.] A partial citation at Cramer Fish Science website (http://www.fishsciences.net/reports/index.php) (affiliation of at least one of the authors is this company) refers to "Kootenai River Macroinvertebrate Characterization (2009 KTOI report)" being a Series. The Cramer Fish Sciences website gives report citation info: http://www.fishsciences.net/reports/index.php. --pjp.]

SWAP (2/19/2016) citation:
Holderman C, Anders P, Shafii B, Lester G. 2009. Characterization of the Kootenai River aquatic macroinvertebrate community before and after experimental nutrient addition, 2003–2006. Chapter 3; 2009 KTOI Report. Report prepared for the Kootenai Tribe of Idaho. [publisher unknown]. 88 p. Published through the Information Bridge: DOE Scientific and Technical Information. [accessed 2015 Jun 1]. https://pisces.bpa.gov/release/documents/documentviewer.aspx?doc=P110393