Short-Term Effects on Riverine Ephemeroptera, Plecoptera, and Trichoptera of Rotenone and Aluminum Sulfate Treatment to Eradicate Gyrodactylus salaris

ABSTRACT

In Norway, attempts have been made to eradicate the salmon parasite Gyrodactylus salaris from infested rivers using solutions containing either rotenone or aqueous aluminum and sulfuric acid (AlS). When Steinkjewassdraget, a river system in central Norway, was being treated in summer 2007 with AIS and the rotenone formulation CFT Legumine, we investigated the immediate drift of Ephemeroptera, Plecoptera and Trichoptera in the River Rølla. The rotenone treatment induced catastrophic drift and caused mortality to the ephemeropterans Baetis fuscatus/scambus, Baetis muticus, Baetis niger, Baetis rhodani, Heptagenia dalecarlica, Heptagenia sp., and Ecdyonurus joernensis; to the plecopterans Amphinemura borealis, Amphinemura sp., Capniidae indet., Leuctrafusca, Leuctra sp., Nemoura avicularis, Perlodidae indet., Protonemura meyeri, and Taeniopteryx nebulosa; and, to the tichopterans Hydropsyche sp., Polycentropodidae indet., Polycentropus flavomaculatus, and Rhyacophila nubila. The AlS treatment induced catastrophic drift and had negative effects on the trichopteran Rhyacophila nubila, and the ephemeropterans B. rhodani, B. niger, and possibly B. fuscatus/scambus, although its effects on these species were less pronounced than those from the rotenone treatment. No effects on drift densities or mortalities were recorded for any of the plecopterans during the AIS treatment.