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Effects of the herbicide imazapyr on juvenile Oregon spotted frogs

Environmental Toxicology and Chemistry

By:
, , ,
DOI: 10.1002/etc.2048

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Abstract

Conflict between native amphibians and aquatic weed management in the Pacific Northwest is rarely recognized because most native stillwater-breeding amphibian species move upland during summer, when herbicide application to control weeds in aquatic habitats typically occurs. However, aquatic weed management may pose a risk for aquatic species present in wetlands through the summer, such as the Oregon spotted frog (OSF, Rana pretiosa), a state endangered species in Washington. Acute toxicity of herbicides used to control aquatic weeds tends to be low, but the direct effects of herbicide tank mixes on OSFs have remained unexamined. We exposed juvenile OSFs to tank mixes of the herbicide imazapyr, a surfactant, and a marker dye in a 96-h static-renewal test. The tank mix was chosen because of its low toxicity to fish and its effectiveness in aquatic weed control. Concentrations were those associated with low-volume (3.5 L/ha) and high-volume (7.0 L/ha) applications of imazapyr and a clean-water control. Following exposure, frogs were reared for two months in clean water to identify potential latent effects on growth. Endpoints evaluated included feeding behavior, growth, and body and liver condition indices. We recorded no mortalities and found no significant differences for any end point between the herbicide-exposed and clean-water control frogs. The results suggest that imazapyr use in wetland restoration poses a low risk of direct toxic effects on juvenile OSFs.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Effects of the herbicide imazapyr on juvenile Oregon spotted frogs
Series title:
Environmental Toxicology and Chemistry
DOI:
10.1002/etc.2048
Volume
32
Issue:
1
Year Published:
2013
Language:
English
Publisher:
Wiley
Publisher location:
Hoboken, NJ
Contributing office(s):
Washington Cooperative Fish and Wildlife Research Unit
Description:
8 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
228
Last page:
235
Country:
United States
State:
Oregon