Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France; University of Bordeaux, EPOC, UMR 5805, F-33120 Arcachon, France.
Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France.
Sci Total Environ. 2014 Mar 1;473-474:496-506. doi: 10.1016/j.scitotenv.2013.12.060. Epub 2014 Jan 3.
This study deals with the use of Polar Organic Chemical Integrative Sampler (POCIS) extracts to assess the impact of low-dose pesticide mixtures on natural biofilm communities originating from either a chronically contaminated or a reference field site. To investigate how natural biofilm communities, pre-exposed to pesticides in situ or not might respond to environmentally realistic changes in pesticide pressure, they were exposed to either clean water or to POCIS extracts (PE) in order to represent toxic pressure with a realistic pesticide mixture directly isolated from the field. The impacts of PE were assessed on structure, physiology and growth of biofilms. Initial levels of tolerance of phototrophic communities to PE were also estimated at day 0. PE exposure led to negative effects on diatom growth kinetics independently of in-field biofilm exposure history. In contrast, the impacts observed on dry weight, ash-free dry mass and algal fluorescence-related parameters followed different trends depending on biofilm origin. Exposure to PE induced changes in diatom assemblages for the biofilm originating from the reference field site with higher relative abundance of Eolimna minima and Nitzschia palea with PE exposure. Initial tolerance of phototrophic communities to PE was 8-fold higher for the biofilm originating from the chronically contaminated site compared to the reference field site. The use of POCIS extracts allowed us to highlight both chronic impacts of low doses of a mixture of pesticides on natural communities with regard to biofilm exposure history as well as initial levels of tolerance of phototrophic communities.
本研究利用极性有机化学整合采样器（POCIS）提取物来评估低剂量农药混合物对源自慢性污染或参照现场的天然生物膜群落的影响。为了研究在原位预先暴露于农药的天然生物膜群落如何应对环境中农药压力的实际变化，将它们暴露于清洁水或 POCIS 提取物（PE）中，以便用直接从田间分离出的实际农药混合物来代表有毒压力。评估了 PE 对生物膜结构、生理和生长的影响。还在第 0 天估计了光养生物群落对 PE 的初始耐受水平。PE 暴露会对硅藻生长动力学产生负面影响，而与现场生物膜暴露史无关。相比之下，由于生物膜的起源不同，观察到的对干重、无灰干重和藻类荧光相关参数的影响呈现出不同的趋势。PE 暴露导致源自参照现场的生物膜中的硅藻组合发生变化，PE 暴露后 Eolimna minima 和 Nitzschia palea 的相对丰度更高。与源自参照现场的生物膜相比，源自慢性污染现场的生物膜对 PE 的初始耐受水平高出 8 倍。POCIS 提取物的使用使我们能够突出低剂量农药混合物对生物膜暴露史的慢性影响以及光养生物群落的初始耐受水平。
