Marelize Marsay, Paul J van den Brink, Collins Nimako, Yoshinori Ikenaka, Mayumi Ishizuka, Victor Wepener
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引用次数: 0
Abstract
Pesticides are widely used to meet the food demands of a growing population, with various types used to control pests depending on the crops grown. Rainfall, overspray, and runoff from agricultural fields can wash these insecticides into water bodies, posing documented environmental risks. Imidacloprid is commonly used in Afrotropical regions such as South Africa, yet limited information is available on its toxicity to aquatic ecosystems within this climate region. To address this, a 16-week outdoor microcosm study was conducted, exposing aquatic communities to 0.1, 10 and 250 µg/L imidacloprid under natural conditions. Physicochemical parameters, such as pH, dissolved oxygen, temperature, and various others, were monitored regularly. The microbial community, organic decomposition and zooplankton were largely unaffected by the exposure to imidacloprid. In contrast, 10 and 250 µg/L of imidacloprid led to long-term effects on the macroinvertebrate community, while short-term effects were found in the 0.1 µg/L treatment. Families such as Coenagrionidae were affected across all treatments, while Caenidae and Notonectidae were only affected in the highest treatment. Changes in the community structure resulted in reduced predator abundance (such as Coenagrionidae, Libellulidae and Notonectidae) and increased filter feeders (Culicidae). High temperatures likely increase the toxicity to arthropods when compared to similar studies with lower light intensities and temperatures. Recovery was limited during the post-exposure period, with some families (Baetidae) rebounding quickly, while others, Caenidae and Coenagrionidae, showed delayed recovery. Full recovery of the macroinvertebrate community systems did not occur during the 8-week recovery period, highlighting the importance of unexposed refuges for recolonization. This study provides important field-realistic evidence of the ecological risks associated with imidacloprid use in Southern African freshwater systems.
期刊介绍:
Integrated Environmental Assessment and Management (IEAM) publishes the science underpinning environmental decision making and problem solving. Papers submitted to IEAM must link science and technical innovations to vexing regional or global environmental issues in one or more of the following core areas:
Science-informed regulation, policy, and decision making
Health and ecological risk and impact assessment
Restoration and management of damaged ecosystems
Sustaining ecosystems
Managing large-scale environmental change
Papers published in these broad fields of study are connected by an array of interdisciplinary engineering, management, and scientific themes, which collectively reflect the interconnectedness of the scientific, social, and environmental challenges facing our modern global society:
Methods for environmental quality assessment; forecasting across a number of ecosystem uses and challenges (systems-based, cost-benefit, ecosystem services, etc.); measuring or predicting ecosystem change and adaptation
Approaches that connect policy and management tools; harmonize national and international environmental regulation; merge human well-being with ecological management; develop and sustain the function of ecosystems; conceptualize, model and apply concepts of spatial and regional sustainability
Assessment and management frameworks that incorporate conservation, life cycle, restoration, and sustainability; considerations for climate-induced adaptation, change and consequences, and vulnerability
Environmental management applications using risk-based approaches; considerations for protecting and fostering biodiversity, as well as enhancement or protection of ecosystem services and resiliency.