Effects of the herbicide triclopyr on metamorphic northern red-legged frogs

Aquatic herbicides are used to manage invasive emergent plants in and around wetlands. Metamorphic frogs that emerge during the aquatic weed management season may be at risk of herbicide exposure. Metamorphic northern red-legged frogs (Rana aurora) were exposed to a triclopyr tank mix labelled for control of broadleaf emergent aquatic weeds such as invasive purple loosestrife (Lythrum salicaria). The tank mix consisted of Renovate® 3 (triclopyr triethylamine salt [TEA] 44.4%), the modified vegetable oil surfactant Competitor®, and marker dye Hi-Light®. Metamorphs were exposed to the tank mix and a clean-water control for 96 h, then reared in clean water for 60 d. Exposure to the tank mix resulted in no treatment-related mortalities, no effects on behavior immediately post-exposure, and no effects on body or liver condition indices. Exposure to the tank mix resulted in lethargy during exposure and a 1-d delay in completion of metamorphosis. Deformities present in the rearing population confounded results for some endpoints. Observed effects were minimal, especially compared to the potential for ecological impacts from unmanaged invasive plants. This article is protected by copyright. All rights reserved