A hybrid nature-based ecological restoration system stabilizes water quality and food-web recovery in a continuous nutrient-loaded pond.
Abstract
Small water bodies are important hotspots for nutrient transformation but are highly vulnerable to persistent anthropogenic loading. Ecological restoration is often evaluated by short-term pollutant removal, whereas the processes that sustain water quality and ecological function under continuing external inputs remain less understood. Here, we implemented a hybrid nature-based ecological restoration system integrating ecological floating beds, microbial electrochemical system-enhanced floating beds (ECOFB-MES), submerged macrophytes, and ecological revetments in a 2600-m2 shallow rural pond continuously receiving secondary treatment effluent and rainfall-driven runoff. Across pronounced seasonal variability (5-36 °C), the water quality consistently met the surface water Class III standard (GB 3838-2002) and effectively prevented eutrophication. Water-quality persistence was accompanied by aquatic-community recovery, characterized by declining phytoplankton abundance and increasing zooplankton and benthic macroinvertebrates. Increasing sediment ORP coincided with increased Fe(III) abundance and phosphorus fraction redistribution, indicating a shift toward stronger phosphorus retention and a lower potential for internal phosphorus release. Microbial-community restructuring, electrochemically mediated electron transfer, plant nutrient assimilation, and sediment stabilization provided complementary pathways for nutrient transformation and retention. Greenhouse-gas measurements further indicated potential carbon-related co-benefits. These results demonstrate that sustained improvement in nutrient-loaded small water bodies can emerge from coordinated regulation of the water column, sediment-water interface, and aquatic biological community. This study provides field-scale evidence for advancing small-water-body restoration toward integrated ecological stabilization under persistent anthropogenic pressure.
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