University of Washington, Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, Seattle, WA, USA.
Environ Toxicol Chem. 2013 Jan;32(1):228-35. doi: 10.1002/etc.2048. Epub 2012 Nov 23.
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.
在太平洋西北地区，原生两栖动物与水生杂草管理之间的冲突很少被认识到，因为大多数原生静水繁殖的两栖动物在夏季会迁移到高地，而此时通常会施用以控制水生栖息地杂草的除草剂。然而，水生杂草管理可能会对夏季存在于湿地中的水生物种构成风险，例如俄勒冈斑点蛙（OSF，Rana pretiosa），它是华盛顿州的濒危物种。用于控制水生杂草的除草剂的急性毒性往往较低，但除草剂混合罐对 OSF 的直接影响仍未得到检验。我们将幼年 OSF 暴露于除草剂咪唑并吡嗪、表面活性剂和标记染料的混合罐中，进行了 96 小时的静态更新测试。选择这种混合罐是因为它对鱼类的毒性低，并且在控制水生杂草方面有效。浓度与低容量（3.5 L/ha）和高容量（7.0 L/ha）应用的咪唑并吡嗪以及清洁水对照相关。暴露后，青蛙在清洁水中饲养两个月，以确定对生长的潜在潜在影响。评估的终点包括摄食行为、生长以及身体和肝脏状况指数。我们没有记录到死亡事件，并且在暴露于除草剂的青蛙和清洁水对照之间，任何终点都没有发现显著差异。结果表明，在湿地恢复中使用咪唑并吡嗪对幼年 OSF 直接产生毒性影响的风险较低。
