Nanoparticles (NPs) have unique properties, leading to their widespread application in industry, consequently increasing their concentration in aquatic ecosystems. Although environmentally significant concentrations are still low, they tend to increase because of the intense use, posing into risk microalgae communities. Microalgae are primary producers that support food chains in aquatic ecosystems; thus factors that interfere with their physiology can be propagated throughout the food web. The present research investigated the effects of copper nanoparticles (Cu-NPs) in the physiology of a cosmopolitan green microalgae, Ankistrodesmus densus. Here, we focused on environmental NPs levels, so an ample Cu-NPs range was used, 0.3–635 μg L⁻¹. Considering that NPs dissolve into the medium releasing their constituent material, free Cu²⁺ ions were determined and considered as surrogate for NPs concentration, which varied from 2.1 × 10^-9 to 8.4 × 10^-9 mol L⁻¹. The experiment was based in 72 h Cu-NPs exposure, and to access the physiology of A. densus, we monitored population growth, photochemistry of photosynthesis and the content of cell biomolecules (total proteins, carbohydrates and lipids). The results showed that 2.1 × 10^-9 mol L⁻¹ free Cu²⁺ was enough to decrease growth rate, but 2.5x higher Cu was necessary to affect the photosynthetic parameters. Inorganic carbon fixation rate calculated by absolute electron transport rates was affected. Considering cell biomolecules, total proteins accumulated at 6.5 × 10^-9 and kept increasing up to 8.4 × 10^-9 mol L^-1 free Cu²⁺. Because this was not related to biomass formation, we suggest a possible association with cell detoxification mechanisms. The most clear finding that emerged from this study is that environmental Cu-NPs concentrations affect vital functions in the green microalgae A. densus. An implication of this is the possibility of facing problems related to a increase of NPs in aquatic ecosystems in the near future.

纳米粒子（NPs）具有独特的特性，导致其在工业中的广泛应用，因此增加了它们在水生生态系统中的浓度。尽管对环境无害的浓度仍然很低，但由于使用量过大，它们的浓度往往会增加，从而构成危险的微藻群落。微藻是支持水生生态系统食物链的主要生产者；因此，影响其生理的因素可以在整个食物网中传播。本研究调查了铜纳米颗粒（Cu-NPs）在大都会绿色微藻Ankistrodesmus densus的生理学中的作用。在这里，我们关注环境NPs的水平，因此使用了足够的Cu-NPs范围，即0.3–635μgL ^-1。考虑到NP溶解在释放其构成材料的介质中，因此确定了游离的Cu ²⁺离子并认为是NPs浓度的替代物，其浓度范围从2.1×10 ^-9到8.4×10 ^-9 mol L ^-1。该实验基于72 h Cu-NPs暴露，并为了了解A. densus的生理，我们监测了种群增长，光合作用的光化学和细胞生物分子（总蛋白质，碳水化合物和脂质）的含量。结果表明，2.1×10 ^-9 mol L ^-1的游离Cu ²⁺足以降低生长速率，但是需要高2.5倍的Cu才能影响光合参数。通过绝对电子传输率计算的无机碳固定率受到影响。考虑到细胞生物分子，总蛋白质累积为6.5×10 ^-9，并保持增加至8.4×10 ^-9 mol L ^-1游离Cu ²⁺。因为这与生物质的形成无关，所以我们建议可能与细胞排毒机制有关。这项研究得出的最明确的发现是，环境中的铜-NPs浓度会影响绿色微藻A. densus的重要功能。这暗示着在不久的将来可能会面临与水生生态系统中NP含量增加有关的问题。