Stream restoration in the United States is a multi-billion dollar industry. Federal agencies spent $1.5 billion between 1997-2001 to recover steelhead and salmon in the Columbia River Basin.  More recently in 2010, $80 million was spent on Columbia basin watershed restoration to improve salmon and steelhead populations with $30 million allocated to Washington State alone.

Our study evaluated two popular restoration actions to better understand the ecological influence of a logjam installation and addition of salmon carcasses to increase the biomass of listed fish. Specifically, (1) we used a reach scale restoration of logjams as a field-manipulative experiment to quantify their effect on transient storage, hyporheic exchange, and nutrient uptake on the Tucannon River, WA; and, (2) we conducted a pilot study in the Methow River Basin, WA to understand how salmon carcass analogs influence invertebrate community production.

Our results indicate that logjam installation led to increased hyporheic exchange. Immediately after log jam installation, hyporheic exchange in the study site increased 56% compared to a 31% decrease in the reference site. The study site also changed from 100% upwelling to 63% upwelling and 37% downwelling immediately after restoration, demonstrating how logjams increase the heterogeneity of hyporheic exchange. Nutrient uptake was not significantly impacted by logjam installation, which could be due to a lag time either between installation and biotic response or methodological issues.

Previous studies on the effects of salmon carcasses and salmon carcass analogs have shown positive effects of salmon material on invertebrate communities, however, these measurements did not indicate the contribution of direct consumption to salmon carcass and salmon carcass analog effects on secondary production responses. By examining invertebrate gut contents, we provide an estimate of the contribution of direct consumption to salmon carcass effects on secondary production.

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