Streams draining through agricultural catchments are subjected to multiple stressors including pollution with nutrients and pesticides. Pesticides, in interaction with other agricultural stressors, can impact microbial diversity and key ecosystem processes underlying the delivery of ecosystem services from streams. The understanding of how such stressors interact to alter ecosystem structure and function and how responses of biota reflect their longer-term disturbance history remains limited. Effects of the fungicide chlorothalonil on litter breakdown rates of riparian tree leaves of Ficus racemosa and sedge Panicum maximum were assessed in 40-day indoor microcosm systems. Litter breakdown rates were analysed in microcosms treated with chlorothalonil concentrations of 0.01, 0.025, 0.10, 0.25 and 1.0 mg/L and in control tanks without pesticides using the ANCOVA test. The results of the study indicated a significant reduction (P < 0.05) of litter breakdown rate in chlorothalonil-treated tanks compared to the control tanks in terms of reduction percentage of dry weight and organic matter, microbial community sporulation and nutrient content. These alterations were modulated by the litter quality and microbial colonisations on leaf materials. Findings of the study emphasise the importance of considering indirect effects of pesticides on ecological processes. Stressing the need for deeper insight into how multiple stressors can affect the functioning of aquatic ecosystems and associated services.

流经农业集水区的河流受到多种压力因素的影响，包括营养物质和杀虫剂的污染。农药与其他农业压力因素相互作用，可以影响微生物多样性和关键的生态系统过程，这些过程是从溪流中提供生态系统服务的基础。对这些压力源如何相互作用以改变生态系统结构和功能以及生物群的反应如何反映其长期干扰历史的理解仍然有限。杀菌剂百菌清对总状榕树和莎草Panicum河岸树叶凋落物分解率的影响在 40 天的室内微观系统中进行了评估。使用 ANCOVA 测试在用 0.01、0.025、0.10、0.25 和 1.0 毫克/升的百菌清处理的微观世界和没有杀虫剂的对照池中分析凋落物分解率。研究结果表明显着减少（P < 0.05) 百菌清处理池的凋落物分解率与对照池相比，在干重和有机物的减少百分比、微生物群落孢子形成和养分含量方面。这些变化是由凋落物质量和叶片材料上的微生物定植调节的。研究结果强调了考虑农药对生态过程的间接影响的重要性。强调需要更深入地了解多种压力因素如何影响水生生态系统和相关服务的功能。