Acute Toxicity of Two Lampricides, 3-Trifluoromethyl-4-Nitrophenol (TFM) and a TFM:1% Niclosamide Mixture, to Sea Lamprey, Three Species of Unionids, Haliplid Water Beeltes, and American Eel

摘要

We conducted a series of toxicological treatments with 3- trifluoromethyl-4-nitrophenol (TFM) and a TFM:1% 2,5- dichloro-4-nitrosalicylanilide (niclosamide) mixture, two compounds used to control larval sea lamprey (Petromyzon marinus) in Great Lakes tributaries, to evaluate the acute toxicity of the lampricides to a number of nontarget species of concern. Treatments were conducted with yellow stage American eel (Anguilla rostrata), adult and larval haliplid water beetles (Haliplus spp.), a surrogate for the endangered Hungerford's crawling water beetle (Brychius hungerfordi), and adults of three unionid species--giant floater (Pyganadon grandis), fragile papershell (Leptodea fragilis), and pink heelsplitter (Potamilus alatus). Treatments were conducted using a serial dilution system consisting of nine test concentrations and an untreated control with 20% dilution between concentrations. Narcosis was evident among giant floaters exposed to the TFM and the TFM:1% niclosamide mixture and among pink heelsplitters exposed to the TFM:1% niclosamide mixture only but mostly at concentrations greater than 2-fold that required to kill 100% of larval sea lamprey (minimum lethal concentration (MLC)). Tests with the haliplid beetle suggest the risks to the Hungerford's crawling water beetle associated with TFM applications are minimal. Concentrations over 2-fold the sea lamprey MLC did not kill adult or larval water beetles.