Wednesday, May 28, 2008 - 5:00 PM
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Aquatic invertebrate response to rotenone treatment of a high alpine lake, yellowstone national park

Jeffrey L. Arnold and Todd M. Koel. Yellowstone National Park, PO Box 168, Yellowstone Park, WY 82190

During August 2006, Yellowstone National Park treated a small lake with two applications of rotenone (CFT-Legumine) to remove non-native fish.  This was the first step towards native fish restoration in the Specimen Creek watershed in the northwest corner of the park.  CFT Legumine is a relative new formulation of rotenone in the United State that doesn’t contain petroleum hydrocarbon solvents that are used in conventional rotenone formulas.  As a result, CFT Legumine is less harmful to the environment but effects on non-target organisms, such as invertebrates, is poorly understood.  We conducted pre- and post- treatment studies on invertebrate communities within the inlet and outlet streams as well as benthic and littoral areas of the lake.  Both pre- and post- treatment studies indicate that midge larvae were the most common invertebrate group in the stream and lake benthos with increasing densities after rotenone treatment.  Results from the stream invertebrate samples indicate that mayfly, stonefly, and caddisfly larvae were most susceptible to rotenone with some taxa experiencing 100% mortality.  One year after treatment, however, most invertebrate taxa had recovered with densities exceeding pre-treatment conditions.  Higher invertebrate densities could be a result of the absence of fish predation the year following treatment.


Web Page: rotenone, yellowstone, invertebrates

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