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Low-dose stimulation of growth of the harmful alga, Prymnesium parvum, by glyphosate and glyphosate-based herbicides
Harmful Algae ( IF 6.6 ) Pub Date : 2018-11-17 , DOI: 10.1016/j.hal.2018.11.004
Brittanie L. Dabney , Reynaldo Patiño

Glyphosate-based herbicides (GBH) are widely used around the globe. While generally toxic to phototrophs, organic phosphorus in glyphosate can become available to glyphosate-resistant phytoplankton and contribute to algal bloom development. Few studies have examined the effects of GBH on growth of eukaryotic microalgae and information for the toxic bloom-forming haptophyte, Prymnesium parvum, is limited. Using a batch-culture system, this study examined the effects on P. parvum growth of a single application of Roundup Weed and Grass Killer Super Concentrate Plus® (Roundup SC), Roundup Weed and Grass Killer Ready-to-Use III® (Roundup RtU), and technical-grade glyphosate at low concentrations [0–1000 μg glyphosate acid equivalent (ae) l−1]. Roundup formulations differ in the percent of glyphosate as active ingredient (Roundup SC, ∼50%; Roundup RtU, 2%), allowing indirect evaluation of the influence of inactive ingredients. Roundup SC enhanced exponential growth rate at 10–1000 μg glyphosate ae l−1, and a positive monotonic association was noted between Roundup SC concentration and early (pre-exponential growth) but not maximum cell density. Glyphosate and both Roundup formulations enhanced growth rate at 100 μg glyphosate l−1, but only Roundup SC and glyphosate significantly stimulated early and maximum density. This observation suggests the higher concentration of inactive ingredients and other compounds in Roundup RtU partially counteracts glyphosate-dependent growth stimulation. When phosphate concentration was varied while maintaining other conditions constant, addition of Roundup SC and glyphosate at 100 μg l−1 influenced growth more strongly than equivalent changes in phosphate-associated phosphorus. It appears, therefore, that low doses of glyphosate stimulate growth by mechanisms unrelated to the associated small increases in total phosphorus. In conclusion, glyphosate and GBH stimulate P. parvum growth at low, environmentally relevant concentrations. This finding raises concerns about the potential contribution to P. parvum blooms by glyphosate-contaminated runoff or by direct application of GBH to aquatic environments.



中文翻译:

草甘膦和基于草甘膦的除草剂低剂量刺激有害藻类小球藻的生长

草甘膦基除草剂(GBH)在全球范围内被广泛使用。虽然通常对光养生物有毒,但草甘膦中的有机磷可用于抗草甘膦的浮游植物,并有助于藻华的形成。很少有研究检查过GBH对真核微藻生长的影响,而且关于形成有毒水华的八倍体植物小生小球藻的信息有限。使用分批培养系统,本研究检查了一次应用农达杂草和杀草剂超级浓缩液Plus®(Roundup SC),农达杂草和草杀手即用型III®(农化剂)对小白菜生长的影响 RtU)和低浓度的工业级草甘膦[0–1000μg草甘膦酸当量(ae)l -1]。综述配方中草甘膦作为有效成分的百分比有所不同(Roundup SC,约50%; Roundup RtU,2%),从而可以间接评估非活性成分的影响。Roundup SC在10–1000μg草甘膦ae l -1时提高了指数生长速率,并且在Roundup SC浓度和早期(指数前生长)之间发现了正单调关联,但没有达到最大细胞密度。草甘膦和两种农达制剂均提高了100μg草甘膦-1的生长速率,但只有Roundup SC和草甘膦能显着刺激早期和最大密度。该观察结果表明,Roundup RtU中较高浓度的非活性成分和其他化合物部分抵消了草甘膦依赖性生长刺激。当在保持其他条件不变的情况下改变磷酸盐浓度时,与磷酸盐相关的磷的当量变​​化相比,添加100μgl -1的Roundup SC和草甘膦对生长的影响更大。因此,看来低剂量的草甘膦是通过与总磷的少量增加无关的机制刺激生长的。总之,草甘膦和GBH刺激小菜蛾在与环境相关的低浓度下生长。这一发现引起了人们的潜在贡献的担忧P.孢子虫草甘膦污染径流或GBH到水生环境直接应用的花朵。

更新日期:2018-11-17
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