In freshwater environments, the relative contributions of top-down and bottom-up effects on invertebrate communities in relation to productivity are largely ecosystem dependent. Artificial wetlands are increasingly developed to compensate for the loss of natural wetlands; however, their trophic processes remain poorly studied. The present study aimed to evaluate the respective contributions of bottom-up and top-down processes in structuring benthic food webs of three artificial wetlands with varying levels of benthic primary productivity. We found that phototrophic-based food webs in our artificial wetlands were controlled from the bottom-up by primary productivity and algal biomass developing at the water–sediment interface. No significant top-down control of herbivore species by invertebrate predators was detected even in the wetland with the highest productivity. Increased richness of invertebrate grazers and scrapers with benthic primary productivity and algal biomass might have dampened the trophic cascade from predators to primary producers. In contrast with the phototrophic-based food web, analyses performed on the detritus-based food web showed that deposit-feeder invertebrate abundance was not correlated with the quantity of organic matter in sediments, suggesting no bottom-up effect of sedimentary organic matter content on deposit-feeders. More surprisingly, deposit-feeders, especially aquatic oligochaetes, seemed to influence the detritus-based food webs by stimulating organic matter processing and bacterial growth through bioturbation. The present study highlights the occurrence of contrasting trophic processes between phototrophic-based and detritus-based food webs which can have implications on ecosystem functions, such as nutrient cycling and energy fluxes.

中文翻译：

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自下而上的过程控制着无鱼人工湿地的底栖大型无脊椎动物群落和食物网结构

在淡水环境中，自上而下和自下而上对无脊椎动物群落的影响相对于生产力的贡献在很大程度上取决于生态系统。人工湿地日益发展，以补偿自然湿地的损失。然而，它们的营养过程仍然缺乏研究。本研究旨在评估自下而上和自上而下的过程在构造三个具有不同底栖初级生产力水平的人工湿地的底栖食物网中的各自贡献。我们发现，人工湿地中以营养养生为基础的食物网从下而上受到主要生产力和水-沉积物界面处藻类生物量的控制。即使在生产力最高的湿地中，也未检测到无脊椎动物捕食者对草食动物物种的自上而下的有效控制。具有底栖初级生产力和藻类生物量的无脊椎动物放牧者和刮板的丰富性增加可能会削弱从捕食者到初级生产者的营养级联。与基于光养性的食物网相反，在基于碎屑的食物网上进行的分析表明，沉积物进食者无脊椎动物的丰度与沉积物中有机物的数量无关，这表明沉积有机物含量对土壤无底向上影响。存款给料机。更令人惊讶的是，沉积物喂食器，尤其是水生寡头鱼类，似乎通过刺激生物扰动来刺激有机物质的加工和细菌的生长，从而影响碎屑食物网。