Aquatic organisms are exposed to several compounds that occur in mixtures in the environment. Thus, it is important to investigate their impacts on organisms because these combined effects can be potentiated. Cobalt (Co) and nickel (Ni) are metals that occur in the environment and are used in human activities. To the best of our knowledge, there are no studies that investigated the combined effects of these metals on a freshwater Chlorophyceae. Therefore, this study analyzed the isolated and combined effects of Co and Ni in cell density, physiological and morphological parameters, reactive oxygen species (ROS), carbohydrates and photosynthetic parameters of the microalga Raphidocelis subcapitata. Data showed that Co affected the cell density from 0.25 mg Co L⁻¹; the fluorescence of chlorophyll a (Chl a) (0.10 mg Co L⁻¹); ROS production (0.50 mg Co L⁻¹), total carbohydrates and efficiency of the oxygen evolving complex (OEC) at all tested concentrations; and the maximum quantum yield (Φ_M) from 0.50 mg Co L⁻¹. Ni exposure decreased ROS and cell density (0.35 mg Ni L⁻¹); altered Chl a fluorescence and carbohydrates at all tested concentrations; and did not alter photosynthetic parameters. Regarding the Co-Ni mixtures, our data best fitted the concentration addition (CA) model and dose-ratio dependent (DR) deviation in which synergism was observed at low doses of Co and high doses of Ni and antagonism occurred at high doses of Co and low doses of Ni. The combined metals affected ROS production, carbohydrates, Φ_M, OEC and morphological and physiological parameters.

水生生物暴露于环境中以混合物形式存在的多种化合物。因此，研究它们对生物体的影响非常重要，因为这些综合效应可以被增强。钴 (Co) 和镍 (Ni) 是存在于环境中并用于人类活动的金属。据我们所知，还没有研究调查这些金属对淡水绿藻的综合影响。因此，本研究分析了Co和Ni对微藻Raphidocelis subcapitata细胞密度、生理和形态参数、活性氧（ROS）、碳水化合物和光合参数的单独和联合影响。^{数据显示，Co 从 0.25 mg Co L -1}开始影响细胞密度；叶绿素a (Chl a ) (0.10 mg Co L ^-1 )的荧光；所有测试浓度下的 ROS 产量 (0.50 mg Co L ^-1 )、总碳水化合物和析氧复合物 (OEC) 效率；以及0.50 mg Co L ^-1的最大量子产率 (Φ _M ) 。Ni暴露降低了ROS和细胞密度（0.35 mg Ni L ^-1）；在所有测试浓度下改变了叶绿素a荧光和碳水化合物；并且不改变光合参数。关于Co-Ni混合物，我们的数据最适合浓度加成（CA）模型和剂量比依赖性（DR）偏差，其中在低剂量Co和高剂量Ni下观察到协同作用，在高剂量Co下观察到拮抗作用和低剂量的镍。组合金属影响 ROS 产生、碳水化合物、Φ _M、OEC 以及形态和生理参数。