NEEA/CRHEA/SHS and PPG-SEA, São Carlos Engineering School, University of São Paulo, Av Trabalhador São Carlense, 400, 13.560-970, São Carlos, Brazil.
NEEA/CRHEA/SHS and PPG-SEA, São Carlos Engineering School, University of São Paulo, Av Trabalhador São Carlense, 400, 13.560-970, São Carlos, Brazil.
Ecotoxicol Environ Saf. 2020 Dec 15;206:111180. doi: 10.1016/j.ecoenv.2020.111180. Epub 2020 Aug 27.
The occurrence of pesticides and their mixtures in the environment can alter the ecological relationships between aquatic food chains. Since fipronil and 2,4-dichlorophenoxyacetic acid (2,4-D) are commonly found together in Brazilian water bodies, the present study aimed to investigate through an integrative approach the toxicity mechanisms of environmentally relevant concentrations of pesticides Regent® 800 WG (active ingredient - a.i. fipronil), DMA® 806 BR (a.i. 2,4-D) isolated and in mixtures on the green alga Raphidocelis subcapitata using multiple parameters: physiological (growth rate and chlorophyll a fluorescence), morphological (cell complexity and size), biochemical (composition of lipid classes) and related to the photosynthetic activity (variable fluorescence, the maximum quantum yield of the photosystem II - PSII - and the efficiency of the oxygen evolving complex - OEC - of PSII). The results indicated that fipronil significantly inhibited algal population growth, increased the chlorophyll a content (observed by fluorescence), cell size and lipid class content of triacylglycerol (TAG), free fatty acid (FFA) and acetone mobile polar lipid (AMPL) and, on the other hand, decreased variable fluorescence of algae. The tested concentrations of 2,4-D increased the chlorophyll a fluorescence, the cell size and the lipid classes TAG and FFA. The pesticide mixtures have had more effects on algae than isolated compounds, causing alterations in all parameters analyzed, including photosynthetic activity (maximum quantum yield and efficiency of the oxygen evolving complex of the PSII), in which no alterations were observed for the toxicity of the single pesticides. The results suggest that these analyses are important to evaluate pesticide toxicity mechanisms in ecological risk assessments of tropical regions. Thus, here we demonstrate the importance of using multiple parameters in ecotoxicological studies to obtain a better understanding of the toxicity of these compounds for phytoplankton.
环境中农药及其混合物的存在会改变水生食物链的生态关系。由于氟虫腈和 2,4-二氯苯氧乙酸（2,4-D）在巴西水体中通常同时存在，本研究旨在通过综合方法研究环境相关浓度的农药 Regent® 800 WG（有效成分 - a.i. 氟虫腈）、DMA® 806 BR（有效成分 2,4-D）单独和混合物对绿藻莱茵衣藻的毒性机制，使用多个参数：生理（生长速率和叶绿素 a 荧光）、形态（细胞复杂性和大小）、生化（脂质类组成）和与光合作用活性相关的参数（可变荧光、光合作用系统 II 的最大量子产率 - PSII - 和 PSII 的氧气释放复合物的效率 - OEC）。结果表明，氟虫腈显著抑制藻类种群生长，增加叶绿素 a 含量（通过荧光观察）、细胞大小和三酰基甘油（TAG）、游离脂肪酸（FFA）和丙酮可移动极性脂质（AMPL）的脂质类含量，另一方面，降低了藻类的可变荧光。测试浓度的 2,4-D 增加了叶绿素 a 荧光、细胞大小和 TAG 和 FFA 脂质类。农药混合物对藻类的影响大于单独化合物，导致所有分析参数发生变化，包括光合作用活性（PSII 的最大量子产率和氧气释放复合物的效率），单一农药的毒性没有观察到变化。结果表明，这些分析对于评估热带地区生态风险评估中的农药毒性机制非常重要。因此，我们在这里证明了在生态毒理学研究中使用多个参数的重要性，以更好地了解这些化合物对浮游植物的毒性。
