Metals may cause damage to the biota of contaminated environments. Moreover, using multiple endpoints in ecotoxicological studies is useful to better elucidate the mechanisms of toxicity of these compounds. Therefore, this study aimed to evaluate the effects of cadmium (Cd) and cobalt (Co) on growth, biochemical and photosynthetic parameters of the microalgae Raphidocelis subcapitata, through quantification of lipid classes composition, chlorophyll a (Chl a) content, maximum (Φ_M) and effective (Φ’_M) quantum yields and efficiency of the oxygen-evolving complex (OEC). Both metals affected the algal population growth, with an IC_50–96h of 0.67 and 1.53 μM of Cd and Co, respectively. Moreover, the metals led to an increase in the total lipid content and reduced efficiency of OEC and Φ_M. Cell density was the most sensitive endpoint to detect Cd toxicity after 96 h of treatment. Regarding Co, the photosynthetic parameters were the most affected and the total lipid content was the most sensitive endpoint as it was altered by the exposure to this metal in all concentrations. Cd led to increased contents of the lipid class wax esters (0.89 μM) and phospholipids (PL - at 0.89 and 1.11 μM) and decreased values of triglycerides (at 0.22 μM) and acetone-mobile polar lipids (AMPL - at 0.44 and 1.11 μM). The percentage of free fatty acids (FFA) and PL of microalgae exposed to Co increased, whereas AMPL decreased in all concentrations tested. We were able to detect differences between the toxicity mechanisms of each metal, especially how Co interferes in the microalgae at a biochemical level. Furthermore, to the best of our knowledge, this is the first study reporting Co effects in lipid classes of a freshwater Chlorophyceae. The damage caused by Cd and Co may reach higher trophic levels, causing potential damage to the aquatic communities as microalgae are primary producers and the base of the food chain.

金属可能会损坏受污染环境的生物。此外，在生态毒理学研究中使用多个终点有助于更好地阐明这些化合物的毒性机理。因此，本研究旨在通过定量脂质类成分，叶绿素a（Chl a）含量，最大（Φ）来评估镉（Cd）和钴（Co）对微藻Raphidocelis subcapitata生长，生化和光合参数的影响。_中号）和有效（Φ”_中号）量子产率和放氧复合物（OEC的效率）。两种金属都影响藻类种群的增长，IC _50-96hCd和Co分别为0.67和1.53μM。此外，这些金属导致的增加的总脂质含量和减少的OEC和Φ效率_中号。在治疗96小时后，细胞密度是检测Cd毒性的最敏感终点。关于Co，光合参数受到的影响最大，总脂质含量是最敏感的终点，因为在所有浓度下暴露于这种金属都会改变它。镉导致脂质类蜡酯（0.89μM）和磷脂（PL-在0.89和1.11μM）的含量增加，甘油三酸酯（0.22μM）和丙酮移动极性脂质（AMPL-在0.44和1.11μM的值）降低）。在所有测试浓度下，暴露于Co的微藻的游离脂肪酸（FFA）和PL的百分比均增加，而AMPL则降低。我们能够检测出每种金属的毒性机制之间的差异，尤其是在生化水平上Co如何干扰微藻。此外，据我们所知，这是第一项报道Co对淡水绿藻类脂质作用的研究。Cd和Co造成的破坏可能达到更高的营养水平，因为微藻是主要生产者和食物链的基础，因此可能对水生生物造成破坏。