The herbicide Fusilade Forte^® (FF) is widely applied in agricultural weed management and in the management of the invasive saltmarsh grass, Spartina anglica (ricegrass or cordgrass). FF (active ingredient fluazifop-P acid, FPA) is selective for poaceous grasses. Its primary mode of action is inhibition of the acetyl coenzyme-A carboxylase (ACCase) specific to this taxonomic group, and its secondary mode is by promotion of oxidative stress. FF is applied to S. anglica infestations in the intertidal zone, in proximity to seagrass meadows. Despite the potential for vital seagrass ecosystems to be exposed to FF, there is limited knowledge of any potential impacts. We investigated impacts of FPA on the endemic Australian seagrass, Zostera nigricaulis, measuring ACCase activity and parameters that reflect oxidative stress: photosynthetic performance, lipid peroxidation and photosynthetic pigment content. Seagrass was exposed to FF (0.01–10 mg L⁻¹ FPA and a control) for 7 d, followed by a 7-d recovery in uncontaminated seawater. An enzyme assay demonstrated that FPA ≤10 mg L⁻¹ did not inhibit the activity of ACCase isolated from Z. nigricaulis, demonstrating that this seagrass is resistant to FF's primary mode of action. However, physiological impacts occurred following 7 days exposure to ≥0.1 mg L⁻¹ FPA, including up to a 72% reduction in photosynthetic pigment concentration. After 7-d recovery, photosynthetic pigment content improved in treatment plants; however, treated plants exhibited higher levels of lipid peroxidation. This study demonstrates that while Z. nigricaulis is resistant to FF's primary mode of action, significant physiological impacts occur following 7 days exposure to ≥0.1 mg L⁻¹ FPA. This study provides valuable information on the effects of FF on a non-target species that can better inform approaches to Spartina management in coastal seagrass ecosystems.

除草剂Fusilade复^®（FF）被广泛地应用于农业杂草管理，并在侵入盐沼草，管理大米草（落芒草或大米草）。FF（有效成分fluazifop-P酸，FPA）对多孔草具有选择性。它的主要作用方式是抑制该分类基团特异的乙酰辅酶A羧化酶（ACCase），其次要作用方式是促进氧化应激。FF应用于潮间带邻近海草草甸的英国链球菌侵扰。尽管重要的海草生态系统有可能暴露于实蝇，但对任何潜在影响的了解仍然有限。我们调查了FPA对澳大利亚特有海草Zostera nigricaulis的影响，测量ACCase活性和反映氧化应激的参数：光合性能，脂质过氧化和光合色素含量。将海草暴露于FF（0.01-10 mg L ^-1 FPA和对照）中7 d，然后在未污染的海水中恢复7 d。酶分析表明，FPA≤10mg L ^-1不会抑制从黑线虫中分离到的ACCase的活性，表明该海草对FF的主要作用方式具有抗性。但是，暴露于≥0.1 mg L ^-1 7天后会产生生理影响FPA，包括光合色素浓度降低多达72％。恢复7天后，处理厂的光合作用色素含量提高了。然而，处理过的植物表现出较高水平的脂质过氧化作用。这项研究表明，尽管黑僵菌对FF的主要作用方式有抵抗力，但在暴露于≥0.1 mg L ^-1 FPA的7天后会发生显着的生理影响。这项研究提供了关于FF对非目标物种的影响的有价值的信息，这些信息可以更好地为沿海海草生态系统中的Spartina管理提供信息。