Eutrophication still is one of the greatest anthropogenic impacts affecting aquatic ecosystems. Food web manipulations to reverse eutrophic conditions have been applied, mainly by reducing fish stocks. However, the long-term results of biomanipulation are still ambiguous. The objective of this study was to evaluate biomanipulation effects on zooplankton functional diversity and production during 24 years of monitoring a shallow temperate lake. Temporal variation in crustacean biomass (CB), zooplankton resource use efficiency (RUE), limnological variables, functional diversity indices and functional traits were assessed using the Mann–Kendall test. The effects of the limnological and functional variables on zooplankton production (CB and RUE) were analyzed by generalized least squares models (GLSs). We found decreasing trends for almost all the limnological variables, indicating a reduction in lake eutrophic conditions. We also observed a decreasing trend in functional traits related to pelagic habitat, filter-feeding mode, herbivore feeding preference and body size. The GLS results showed that functional dispersion and chlorophyll a are important determinants of zooplankton production. The effects of fish biomanipulation produced no significant temporal trends in zooplankton biomass. In fact, the increase in submerged macrophytes promoted littoral food webs, which was likely the main determining factor of the changes in zooplankton functional traits and production.

中文翻译：

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鱼类生物操纵和大型植物管理对温带浅湖浮游动物功能多样性和生产的长期影响

富营养化仍然是影响水生生态系统的最大的人为影响之一。已经通过改变食物网来逆转富营养化条件，主要是通过减少鱼类种群。然而，生物操纵的长期结果仍然是模棱两可的。这项研究的目的是评估在监测浅温带湖泊的24年中生物操纵对浮游动物功能多样性和生产的影响。使用Mann-Kendall检验评估了甲壳类生物量（CB），浮游动物资源利用效率（RUE），语言学变量，功能多样性指数和功能性状的时间变化。通过广义最小二乘模型（GLSs）分析了语言和功能变量对浮游动物产量（CB和RUE）的影响。我们发现几乎所有湖泊学变量的趋势都在下降，这表明湖泊富营养化条件有所减少。我们还观察到与中上层生境，滤食模式，草食动物摄食偏好和体型有关的功能性状的下降趋势。GLS结果表明，功能性分散和叶绿素a是浮游动物生产的重要决定因素。鱼类生物操纵的影响在浮游动物生物量方面没有产生明显的时间趋势。实际上，淹没大型植物的增加促进了沿海食物网，这可能是浮游动物功能性状和产量变化的主要决定因素。食草动物的摄食偏好和体型。GLS结果表明，功能性分散和叶绿素a是浮游动物生产的重要决定因素。鱼类生物操纵的影响在浮游动物生物量方面没有产生明显的时间趋势。实际上，淹没植物的增加促进了沿海食物网，这可能是浮游动物功能性状和产量变化的主要决定因素。食草动物的摄食偏好和体型。GLS结果表明，功能性分散和叶绿素a是浮游动物生产的重要决定因素。鱼类生物操纵的影响在浮游动物生物量方面没有产生明显的时间趋势。实际上，淹没植物的增加促进了沿海食物网，这可能是浮游动物功能性状和产量变化的主要决定因素。