Effects of Three Consecutive Rotenone Treatments on the Benthic Macroinvertebrate Fauna of the River Ogna, Central Norway

Abstract

The effects of piscicides on aquatic invertebrates are often studied after one treatment, even though piscicides may be repeatedly applied within river management. Here we investigate the impacts of repeated piscidie treatment on riverine benthic invertebrates. The River Ogna, Norway, was treated with rotenone three times over a 16‐month period. The two first treatments caused temporary density reduction of a few rotenone sensitive benthic invertebrate taxa. Effects of the third treatment were variable with some taxa unaffected while all Plecoptera, were locally extinct. The toxic effect of rotenone increases with water temperature and high water temperature (20 °C) combined with high rotenone concentration was probably the main reason why the benthic community in the third treatment was more negatively affected than during the two previous treatments (4 and 8 °C). Eight months after the treatment benthic densities had not reached pre‐treatment levels, but most taxa had recolonized the treated area within a year. Our data suggest that the severe effects of the third treatment were not influenced by the two former ones. This implies that the timing of piscicide treatment has a greater impact on the benthic invertebrate community than the number of treatments. Copyright © 2015 John Wiley & Sons, Ltd.

Recovery of Freshwater Invertebrates in Alpine Lakes and Streams Following Eradication of Nonnative Trout with Rotenone

“…Patterns in freshwater benthic invertebrate recovery rates are likely attributable to taxonspecific differences in sensitives to rotenone (Kjaerstad et al 2016;Lam Pham et al 2018).…”

“…Rotenone is an effective tool to eliminating invasive fish populations and their associated negative impacts on indigenous fauna (Vinson et al 2010). To date, numerous studies have documented the rapid recovery of non-target aquatic invertebrates (e.g., Kjaerstad and Arnekleiv 2003;Hamilton et al 2009;Eilers et al 2011;Skorupski 2011). Though multiple studies in Utah have demonstrated much longer recovery times or extirpation of certain taxa (Binns 1967;Mangum and Madrigal 1999;Whelan 2002), these projects used multiple treatments and higher rotenone concentrations compared to our study.…”

Long-term responses of benthic invertebrates to rotenone treatment

“…Consequently, the treated river was exposed to rotenone from the lake for several months. Even though the toxic effect of rotenone decreases with decreasing water temperatures (Meadows, 1973, Kjaerstad et al 2015, the long exposure apparently had a pronounced negative effect. In June 2013, eight months after the lake treatment, we recorded the lowest abundance of benthic invertebrates in the treated river.…”

Restoration of Landscapes and Habitats Affected by Established Invasive Species

“…In fluvial aquatic ecosystems, passive restoration of native animal species following removal of non-native species typically relies on downstream drift of organisms originating from untreated, upstream reaches. This is a standard strategy for addressing aquatic insects in streams and is often used as a measure of ecosystem recovery (e.g., Kjaerstad et al 2015). Upstream migration by native taxa from areas downstream of treated reaches is rarely feasible; these locations are often the sources of the invading non-native taxa, and the installation of structures that prevent recolonization by invasive species similarly constrains native taxa (Fausch et al 2009).…”