Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires-C1428EHA, Buenos Aires, Argentina.
Ecotoxicol Environ Saf. 2012 Jul;81:106-13. doi: 10.1016/j.ecoenv.2012.04.024. Epub 2012 May 16.
The use of glyphosate has increased dramatically during the past years around the world. Microbial communities are altered when glyphosate reaches water bodies. The freshwater golden mussel Limnoperna fortunei is an invasive species that has rapidly dispersed since it was introduced in Argentina two decades ago. Mussels alter aquatic conditions through their filtrating activity by increasing water clarity and nutrient recycling. We aim to evaluate the potential capacity of the golden mussel to reduce glyphosate concentration in water, in laboratory conditions. Firstly, the evasive response of mussels to glyphosate (10, 20, and 40 mg l⁻¹) was evaluated and a toxicity test was carried out for these concentrations. A three-week experiment was then performed to assess glyphosate variation under mussel presence for two mussel sizes. Finally, mussels' role on glyphosate concentration was evaluated considering different mussel parts (living organisms and empty shells) through another three-week experiment. Laboratory experiments were performed in triplicate using 2-l microcosms. An initial glyphosate concentration between 16 and 19 mg l⁻¹ was used, and when mussels or valvae were added, 20 organisms per aquaria were used. Samples were obtained at days 0, 1, 2, 4, 8, 14, and 21. Glyphosate decreased by 40% under large mussel presence in both experiments, and was reduced by 25% in empty shell treatments. We believe that part of the herbicide that disappears from the water column is adsorbed in valvae surface, while another proportion is being mineralized by microbial communities in shells' biofilm. The mechanisms by which living mussels increase glyphosate dissipation would be degradation, possibly mediated by bacteria associated to mussel's metabolism. Glyphosate half-life depended on mussel and valvae presence and varied with mussel size. L. fortunei presence (either alive or as empty valvae) alters glyphosate concentration in water. We provide preliminary observations from laboratory experiments, with strong potential ecological consequences, about two stressors that could be acting jointly on the environment.
在过去的几年中，草甘膦的使用在全球范围内急剧增加。当草甘膦到达水体时，微生物群落会发生变化。淡水贻贝 Limnoperna fortunei 是一种入侵物种，自从 20 年前在阿根廷引入以来，它已经迅速扩散。贻贝通过增加水的清澈度和养分循环来改变水生条件。我们旨在评估贻贝在实验室条件下降低水中草甘膦浓度的潜在能力。首先，评估了贻贝对草甘膦（10、20 和 40mg l⁻¹）的逃避反应，并对这些浓度进行了毒性测试。然后进行了为期三周的实验，以评估在两种贻贝大小存在下草甘膦的变化。最后，通过另一个为期三周的实验，考虑贻贝的不同部分（活体和空壳）来评估贻贝对草甘膦浓度的作用。实验室实验在 2L 的微宇宙中重复进行了三次。使用 16 到 19mg l⁻¹之间的初始草甘膦浓度，当添加贻贝或壳时，每个水族箱使用 20 个生物体。在第 0、1、2、4、8、14 和 21 天取样。在两个实验中，大贻贝的存在使草甘膦减少了 40%，而在空壳处理中减少了 25%。我们认为，从水柱中消失的部分除草剂被吸附在壳的表面，而另一部分则被壳的生物膜中的微生物群落矿化。活体贻贝增加草甘膦降解的机制可能是降解，可能是由与贻贝代谢相关的细菌介导的。草甘膦的半衰期取决于贻贝和壳的存在，并且随贻贝的大小而变化。L. fortunei 的存在（无论是活着还是作为空壳）都会改变水中草甘膦的浓度。我们提供了来自实验室实验的初步观察结果，这些结果具有强烈的潜在生态后果，涉及到两种可能对环境产生共同影响的压力源。
